Isotopic constraints on the genesis of world-class REE ...

Goldschmidt Conference Abstracts 2009

Isotopic constraints on the genesis of world-class REE-P-U-Th mineralization, Nolans Bore, Central Australia R. MAAS1*, D. HUSTON2 AND K.HUSSEY3 1

School of Earth Sciences, Univ Melbourne, Australia (*correspondence: [email protected]) 2 Geoscience Australia, Canberra, Australia 3 Arafura Resources, Winellie, NT 0821, Australia The Nolans Bore deposit in central Australia is one of the world’s largest known REE resources (current estimates 30.3 Mt containing 850 kt REE-oxides, 3.9 Mt P2O5, 6100 kt U3O8). Hosted in 1.9-1.8 Ga metasedimentary and metaigneous rocks of the central Arunta region and postdating 1.60-1.57 Ga high-grade metamorphism, primary mineralization occurs in NE-trending swarms of F-apatite veins, associated with allanite, carbonate and calcsilicates. The bulk of the REE is hosted in cheralite, bastnaesite and other REE-rich mineral inclusions in apatite. Key geochemical features include remarkably uniform, strongly fractionated REE patterns (La/Lucn~281, Eu/Eu*0.89), elevated Ca, Sr, Th, U, Y, F, CO2, but low HFSE. The mineralization is of hightemperature hydrothermal origin and, although lacking features such as alkalic minerals or fenitization, may be a distal hydrothermal expression of concealed carbonatitic/alkaline magmatism. U-Pb dating of U-rich (260-700 ppm) F-apatite yields a well-defined upper intercept age of 1244±10 Ma. All other minerals analysed to date (allanite, pyroxene, epidote, garnet, calcite) contain variable amounts of unsupported radiogenic Pb (206Pb/204Pb 35-58), indicating loss of U-Th (or gain of Pb). Initial 87Sr/86Sr ratios vary from 0.7047 to 0.7079, while εNd1224 ranges from -12 to -4; there is no correlation between Sr and Nd isotope ratios. All samples show some inter-mineral Sr-Nd isotopic disequilibrium. The 1244±10 Ma apatite U-Pb age, the only currently available age constraint for mineralization, coincides with a global spike in kimberlite, lamproite and carbonatite emplacement (1300-1130 Ma), and several 1.3-0.7 Ga carbonatite, lamprophyre and alkalic intrusive complexes are known in Central Australia. Nolans Bore may be related to a currently unexposed intrusive of this type. The low 87Sr/86Sr of the ore fluid is consistent with such a source. Nd isotope data are less diagnostic as initial εNd near -10 are characteristic of the local Arunta Block crust at that time; however, low εNd values would be also be consistent with a source ultimately derived from lithospheric mantle.

A809

Enigmatic archaea from the anoxic terrestrial subsurface J.L. MACALADY1*, D.S. JONES1, R. MCCAULEY1, I. SCHAPERDOTH1, D. BLOOM1 AND S. MARIANI2 1

Pennsylvania State Univ. University Park, PA 16802, USA (*correspondence: [email protected]) 2 Gruppo Speleologico CAI, Via Alfieri 9, 60044 Fabriano, Italy Cave divers exploring a remote underwater passage in the sulfidic Frasassi cave system (Italy) discovered unusual, ropelike microbial biofilms in anoxic water. Geochemical data suggest that little redox energy is available for life, consistent with low signal from domain-specific FISH probes. The carbon isotope signatures of the biofilm (-33‰) and DIC (-9‰) indicate in situ production by lithoautotrophs using RuBisCO. 16S rDNA libraries constructed from the biofilm are dominated by archaea in the enigmatic Marine Benthic Group D (MBG-D/DHVE-1) along with diverse sulfate reducing bacteria. Most of the remaining clones affiliate with one of 11 major uncultivated or novel prokaryotic lineages. Diverse dsrAB gene sequences were retrieved from the biofilm, consistent with high sulfate concentrations and undetectable or extremely low oxygen, nitrate, and iron concentrations. Methane is detectable in the anoxic water although no 16S rDNA sequences associated with known methanogens or anaerobic methane oxidizers were retrieved. mcrA gene sequences retrieved from the biofilm are not related to cultivated methanogens or to known anaerobic methane oxidizers.

Figure 1: Summary of 16S rDNA libraries constructed using bacteriaspecific, archaea-specific and universal PCR primers. Our data suggest that novel archaea and bacteria, including MBG-D archaea, are important in the dark, energylimited cave biofilm. These microorganisms and their potentially novel metabolic strategies are relevant for understanding biogeochemistry and biosignatures of nonphotosynthetic, energy-limited environments on the modern and ancient Earth and elsewhere in the solar system.


A810

Are arctic ecosystems exceptionally vulnerable to global emissions of mercury?

The Brazeau Nisku Q-pool: From sour gas reservoir to acid gas storage

R. MACDONALD AND L. LOSETO

H.G. MACHEL

([email protected]) ([email protected])

EAS Department, University of Alberta, Edmonton, Alberta T6G 2E3, Canada ([email protected])

Almost one decade ago atmospheric mercury depletion events (AMDEs) were reported to occur in the High Arctic after polar sunrise (Schroeder et al., 1998), and these depletion events were shown to result in mercury deposition to the surface (Steffen et al., 2008). Although deposited mercury is bioavailable (Lindberg et al., 2002) it remains unclear how much – or even whether – the mercury actually enters foodwebs (Hammerschmidt and Fitzgerald, 2008). These findings raise the question of whether or not the Arctic is an enhanced sink for global mercury emissions, and whether the deposited mercury might explain high mercury concentrations observed in some high trophic level Arctic biota. A recently constructed mercury mass balance for the Arctic Ocean (Outridge et al., 2008) found that atmospheric deposition is important, accounting for perhaps half of the mercury inputs, but that there are also other important sources (ocean currents, rivers) and there is a large reservoir of mercury in the ocean that could be worked on by various biogeochemical processes (e.g., Poulain et al., 2007; Cossa et al., 2009). Perhaps more intriguing is the lack of any correspondence between trends for mercury in Arctic air (Steffen et al., 2008), and mercury trends observed in high-trophic level aquatic animals (Lockhart et al., 2005). This leaves open the questions of whether or not the Arctic is a special sink, what proportion of deposited mercury ends up in food webs (Loseto et al., 2008), what factors produce variability in mercury concentration in biota, and how might recent climate change, especially the melting of ice, alter the Arctic’s mercury cycle (e.g., Macdonald et al., 2005)? These questions need answers before we can properly assess the risks mercury presents to the ecosystem. In this presentation we focus particularly on the Arctic Ocean and approach these questions by first examining what is known about the quantities and pathways of mercury cycling into and out of the Arctic. We then examine abiotic and biotic processes that transform mercury to more toxic or bioavailable forms to be taken up in foodwebs, and present available trend data for mercury in different reservoirs. Finally, we propose how climate change in the cryosphere might alter mercury exposure by releasing archived mercury or transforming cycling mercury. Throughout the discussion we point out weaknesses in our understanding of the mercury cycle that presently limit the development of a realistic model for the mercury cycle in the Arctic.

The Brazeau Nisku Q-Pool in west-central Alberta, Canada, was discovered in the 1980s as a sour gas reservoir in the Upper Devonian Nisku Formation. The host rocks consist almost exclusively of dolomite, with minor amounts of anhydrite. The Brazeau Q-Pool is part of a reef trend that contains oil, sweet and sour gas condensate at depths ranging from about 2300 m in the northeast to more than 4200 m in the southwest, with a thickness of about 80 to 100 m. A unique feature of this play is that the hydrocarbons are contained in numerous closely spaced pools that have been essentially isolated hydrodynamically from one another since hydrocarbon migration and entrapment about 50 - 60 million years ago, as shown by initial reservoir pressures and gas compositions. The hydrodynamic isolation renders these pools suitable for acid gas (H2S + CO2) injection and/or carbon dioxide (CO2) sequestration. Today the Brazeau Nisku Q-Pool is one of more than forty acid gas injection operations currently active in western Canada. A thorough stratigraphic, diagenetic, mineralogical, and hydrogeological evaluation of the Nisku Formation suggests that the injected acid gas will remain in the structure that contains the Q-Pool on a geological time scale. In the unlikely case of migration out of the Q-Pool, the acid gas plume would disperse and dissolve in deep formation waters along the flow path. The only possibility for upward leakage of acid gas rapid enough to be of human concern is through wells that were improperly completed and/or are abandoned and are not monitored.


A811

A new analytical field method for the in situ determination of the oxygen dynamics in groundwater

Iron removal enhancement of a two step calcite passive treatment system at the Iberian Pyrite Belt

LARS MÄCHLER1,3*, MATTHIAS S. BRENNWALD1 1,2 AND ROLF KIPFER

FRANCISCO MACÍAS1*, MANUEL A. CARABALLO1, JOSÉ MIGUEL NIETO1, CARLOS AYORA2 3 AND TOBIAS S. RÖTTING

1

Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland (*correspondence:[email protected]) 2 Institute of Isotope Geochemistry and Mineral Resources, ETH Zurich, 8092 Zurich, Switzerland 3 Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Switzerland The knowledge of oxygen dynamics in groundwater is fundamental to understand biogeochemical processes. However oxygen dynamics can only be studied if the underlying physical gas exchange processes are understood in a mechanistic and quantitative way. In recent years gas exchange processes in porous media were thoroughly studied. The resulting conceptual and quantitative models describe gas/water partitioning in groundwater and yield mechanistic insight in the formation of excess air, a commonly observed super saturation of dissolved atmospheric gases (e.g. oxygen or noble gases) in ground waters. The initial oxygen concentrations typically exceed the atmospheric equilibrium concentration considerably (>20%). Quantification of excess air is therefore crucial to study the biogeochemical turnover of oxygen in natural groundwater. The solubility and diffusion coefficients of O2 in water are similar to those of Ar. However, the Ar concentration in the groundwater is unaffected by the geochemical processes of oxygen turnover. Hence, the concentration of dissolved Ar is a direct proxy that allows quantification of the initial oxygen concentration at recharge. The difference of the initial oxygen concentration with the concentration observed in a groundwater sample corresponds to the oxygen consumed since recharge of this water. We developed a massspectrometric system for in situ analysis of O2 and Ar concentrations in groundwater during field work. The gas probe consists of a membrane inlet that is submerged in the groundwater and separates the water from the gas phase to be analysed. The probe is connected to a quadrupole mass spectrometer (QMS200, SRS) via a tube of several meters length to allow in situ analyses in groundwater wells. A continuous vapor flow transports the gases to be analysed (Ar, O2, N2, and possibly also CH4 and CO2) from the probe to the mass spectrometer. The short response time of the system (seconds to minutes) allows continuous analysis of the dissolved gas concentrations in groundwaters. This enables us to study the O2 dynamics, e.g. during bank infiltration of groundwater in response to the hydraulic conditions of the infiltrating river.

1

Dpt. of Geology, Univ. of Huelva. Avda Fuerzas Armadas s/n 21071 Huelva, Spain (*[email protected]) 2 Institute of Environmental Assessment and Water Research, CSIC, Jordi Girona 18, E-08034 Barcelona, Spain 3 HERO Group, Sir Joseph Swan Institute, 3rd Floor Devonshire Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom The previous calcite passive treatment systems developed at Monte Romero (SW, Iberian Pyrite Belt) have shown a significant effectiveness in iron and aluminum removal from the highly polluted acid mine drainage (AMD) emerging from the mine shaft. However, in previous experiments using two reactive tanks in series filled with calcite Dispersed Alkaline Substrate (Calcite-DAS), Al and Fe were not completely removed. The system was modified to improve treatment efficiency. Anoxic acid discharge of Monte Romero mine flows across several iron terraces where the acidophilic microbes and atmospheric oxigen diffusion cause some iron oxidation and subsequent removal. To enhance this natural attenuation, a 100m3 dam was built after several meters of the iron terraces, and before the input of the passive treatment system (two 3m3 reactive tanks, Calcite-DAS, connected in series with two decantation ponds). AMD treated at Monte Romero has a pH of 3-3.5, a net acidity over 1800 mg/L as CaCO3 equivalents and contains 440 mg/L Zn, 330 mg/L Fe (98% Fe+2), 100 mg/L Al, 3750 mg/L SO4 and 0.1-3 mg/L Cu, As, Pb, Co, Ni and Cd. The natural attenuation (fomented by the dam) and the passive treatment system showed excellents results. In the dam almost 50% of ferrous iron were oxidized and 25% of ferric iron precipitated. As well, 75% of As and 7% of net acidity (140 mg/L as CaCO3) were removed from the emerging AMD. Without the presence of the dam the oxidation and removal of Fe in the iron terraces would be only 6% and 3% respectively. The passive treatment system (Calcite-DAS) eliminated a net acidity of more than 1300 mg/L as CaCO3 equivalents (72%) and removed 100% of Fe, Al, Cu, As, Cr and Pb from the AMD. This pretreatment by the dam requires only minimal maintenance and no additional input of alkaline reagents.

A812


Skarn mineralization and related hydrothermal alterations in Aliabad Cu-porphyry deposit (Taft-Yazd)

Subduction zone magmatism without a slab-derived flux: High-Nb basalts from Sabah (Borneo)

M.A. MACKIZADEH1*, F. DALIRAN2 3 AND B. TAGHIPOUR

COLIN G. MACPHERSON1, KAI KIM CHIANG2, ROBERT HALL2, GEOFF M. NOWELL1, PATERNO R. CASTILLO3 4 AND MATTHEW F. THIRLWALL

1

Department of Geology, Esfahan University, Esfahan, Iran (*[email protected]) 2 Geological Institute, University of Karlsruhe, Karlsruhe, Germany ([email protected]) 3 Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz, Iran ([email protected]) The area is a part of Cenozoic magmatic belt of Central Iran which is contact in West of Yazd province & North-West margin of Shirkuk batolite granite. Nayband terigenous formation is the oldest rock unit as bed rock and has undergone weak contact metamorphism by Shirkuh granite in middle Jurasic. The young intrusive bodies which are mainly leucocrate are granite to granodiorite with Cu-porphyry mineralizations. They have widespread fractures & alterations. Those intrusives have intruded Shirkuh granite, arcosic sandstones & conglomerates of Sangestan formation (lower Cretaceous). Skarns are formed in expense of carbonate huge pebbles of Sangestan conglomerates. The following mineral assemblage has been determined: garnet + epidote + quartz + calcite + pyrite and turquoise. Turquoise (Cu Al6 (PO4)4 (OH) 8 5H2O) is a phosphate mineral with secondary origin that occurs veinlet shape in volcanic rocks. This mineral is accompanied with other mineral such as: alunite, jarosite, iron oxides and (Cu, OH) carbonates in oxidation zone that formed in a late stage after scarnization. Grassular formed in the kaoline, SiO2, CaO and CaCl2 mixture in the 900°C and 2000 atmosphere pressure (Dear et al, 1991). But volastonite and grassular formed in 500°C temperature in the mixture of silica, calcite and aluminum oxide with ratio: 3 SiO2: Al2O3: 3 CaCO3 This reaction supposed for formation of andradite (Dear et al., 1991): 3CaCO3 + Fe2O3 + 3SiO2 = Ca3Fe2Si3O12 + 3CO2 Stable formation condition of andradite is in the high fO2 and temperature> 390°C. 1 and 2 area (Fig. ) that indicate stable condition of garnet-pyrite and quartz. Hydrothrmal alteration took place after contact metamorphism (skarn formation) in intrusive bodies, skarns, conglomerates & specially arcosic sandstones quartz-sericite-pyrite (or phyllic) type alteration is characteristic in those rocks.

1

Department of Earth Sciences, Durham University, UK ([email protected]) 2 Southeast Asia Research Group, Department of Earth Sciences, Royal Holloway University of London, UK 3 Geosciences Research Division, Scripps Institution of Oceanography, USA 4 Department of Earth Sciences, Royal Holloway University of London, UK Low concentrations of High Field Strength Elements (HFSE) and their depletion relative to Large Ion Lithophile Elements (LILE) and Rare Earth Elements (REE) are characteristic of many subduction zone magmas. Some subduction zones, however, have generated basaltic rocks in which HFSE are abundant and only mildly depleted, or even enriched, relative to the LILE. These “high-Nb basalt” have been attributed either to (i) low degree melts derived from beneath the slab, (ii) mantle wedge metasomatised by partial melts of subducted basaltic crust, or (iii) melting of enriched mantle without a significant slab input. Neither of the first two models is consistent with compositions and spatial distributions of Plio-Pleistocene high-Nb basalts from Sabah, NE Borneo. First, the most primitive Sabah basalts are isotopically similar to high-Nb basalts from SW Philippines and several sites in the South China Sea, requiring similar sources throughout SE Asia. This is highly unlikely to result from mantle metasomatism by slab melts. Second, the Sabah rocks are part of a Late-Miocene to Pleistocene low-volume magmatic province extending SW into Borneo and NE into the Philippines. Basement fabrics display similar orientations suggesting that the lithosphere plays a key role in determining the locus of magmatism. Either the sources of high-Nb basalts reside in the lithospheric mantle, or they represent a regional component of the convecting mantle from which melt is transported along lithospheric structures. In either case, the creation of the high-Nb basalt source is independent of recent/active subduction. Sources of high-Nb basalt may melt when subduction induces stress in arc lithosphere and/or upwelling of sub-lithospheric mantle. The presence of highNb basalt in several active arcs suggests that these sources can escape modification by material derived from the slab through the lifetime of a subduction zone.


Reactive transport modelling of a long-term core infiltration experiment with claystone 1

1,2

U. MÄDER * AND TH. GIMMI 1

Institut für Geologie, University of Bern, Blatzerstrasse 3, CH-3012 Bern, Switzerland (*correspondence: [email protected]) 2 Laboratory for Waste Management, Paul Scherrer Insitut, CH-5232 Villigen Switzerland ([email protected]) Argillacious rocks have low hydraulic conductivities (10-10-13 m/s), large sorption and ion exchange capacities, are homogeneous, and are thus consdiered as host rocks for deep storage of radioactive waste in several countries. Constraining multicomponent transport parameters for dissolved species are of importance in this context. A three-year advective-diffusive experiment under a hydrostatic confining pressure with a preserved drill core from Opalinus Clay (mid Jurassic, Switzerland) was used to (1) displace the in situ pore water with an artificail pore water [1], and (2) to monitor the breakthrough of tracres (2H, 18O, 36Cl, Br) and major chemical components (this study). A multicomponent reactive transport model (PHREEQC) was used considering explecitly free porewater and pore water affected by clay-bound diffuse double layers [2], species-specific diffusion coefficients, ion-exchange, and slected carbonate / silicate equilibria. A much faster break-through is observed for Br- (an Cl-) compared to 2H due to anion-exclusion effects and the advective flow regime. While the break-through of individual tracres can be modelled with a classical 1D advection/diffusion approach constraining accessible porosities and effective diffusion coefficients, an adequate multi-component reactive transport model does require the consideration of different types of accessible porosities, e.g. including a diffuse-double layer model [2]. The elution behaviour of cations is constrained by multi-component ion exchange and ionic-strength effects that can drive some of the eluted cation concentrations distinctly above those of the infiltrating solution. 14

[1] Mäder et al. (2004) Proceedings of the 11th International Symposium on Water-Rock Interaction, 445-449, Balkema. [2] Appelo and Wersin (2007). [2] Appelo and Wersin (2007) Env. Sci. Tech., 41, 5002-5007.

A813

Adsorption of transgenic Cry1Ab protein to the silica-water interface MICHAEL MADLIGER, RENÉ P. SCHWARZENBACH AND MICHAEL SANDER* Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Switzerland (*correspondence: [email protected]) Bt crops are genetically modified to produce insecticidal Cry proteins against pests. Bt crops release Cry to soils. Little is known about adsorption of Cry to soil particles, albeit this process governs Cry fate and bioactivity in soils. The aim of this work was to systematically investigate and model the adsorption of model protein Cry1Ab to silica (SiO2) as a function of solution chemistry. To this end, we combined solution-depletion experiments coupled to immunological protein detection with in situ real time adsorption measurements using quartz crystal microbalance (QCM-D). Electrostatics governed the adsorption of Cry1Ab (isoelectric point (IEP) = 6.4) to SiO2 (point of zero charge = 2-3) at I = 50 mM (NaCl). Favorable electrostatics at pH 5 and 6 resulted in fast and pronounced adsorption. At pH 5 and c(Cry1Ab) = 10 µg mL-1, a protein monolayer formed on the SiO2 surface. Conversely, at pH 7 and 8, no adsorption was detected, due to electrostatic repulsion. At I = 10 mM, electrostatics still governed Cry1Ab adsorption. Yet, proteinprotein interactions and/or entropic effects facilitated adsorption resulting in a protein bi-layer and a monolayer on SiO2 at pH 6 and 7, respectively. Also, at pH 8, detectable amounts of Cry adsorbed despite unfavorable electrostatics. Adsorption at both I= 10 mM and 50 mM was highly concentration dependent and reversible. Desorption rates increased with increasing pH of the rinsing buffer. Control experiments involving two additional proteins (bovine serum albumin (IEP 4.6) and hen egg white lysozyme IEP = 10.5)) and positively and negatively charged polymers as adsorbents confirmed the dominant role of electrostatics in Cry1Ab-SiO2 interactions. Irreversible sorption of BSA to SiO2 pointed to structural unfolding of BSA on the surface, resulting in a larger contact area and hence an increase in the activation energy of desorption. Conversely, reversible sorption of Cry1Ab suggested that this protein remained in near native conformation and that an adsorption-desorption cycle of did not result in irreversible structural changes in Cry1Ab and hence loss of its bioactivity. This was confirmed in diet incorporation bioassays using the susceptible pest organism Ostrinia nubilalis, where effect concentrations for 50% growth inhibition of the test organisms were only slightly higher for SiO2-adsorbed than freely dissolved Cry1Ab.

A814


Episodes of gas hydrate dissociation and enhanced methane flux recorded by methane-derived authigenic carbonates in the Gulf of Cadiz V.H. MAGALHAES* AND L.M. PINHEIRO Centre for Environmental and Marine Studies (CESAM) and Geosciences Department, Univ. Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal (*correspondence: [email protected]) Extensive occurrences of mud volcanoes, diapiric ridges, pockmarks and methane seepages in the Gulf of Cadiz, often fault controlled, are characterized by high methane contents in the shallow sediments and by the presence of gas hydrates on the most active structures, indicating that these are preferential pathways for the escape of hydrocarbon-rich deep fluids (mainly methane). Methane-derived authigenic carbonates (MDAC) are found associated with mud volcanoes, diapiric ridges or along faults, mainly along the upper and midcontinental slope, where the Mediterranean Outflow (MO) water is in direct contact with the seafloor. Two distinct groups of MDAC are found in the Gulf of Cadiz: one consisting of dolomite crusts, nodules and chimneys, and the other of aragonite pavements, slabs, crusts and buildups. The widespread abundance of MDAC is interpreted as evidence of several episodes of extensive methane seepage. Considering the minimum and maximum temperature limits admitted to have occurred in the Gulf of Cadiz, some MDAC samples indicate a formation from 18Oenriched pore fluids that could have resulted from a contribution of dissociated gas hydrates to the pore waters from which the authigenic carbonates were formed. The estimated U/Th ages of selected dolomite chimneys indicate episodes of intense precipitation of the authigenic carbonates, that correlate with periods of rapid paleoceanographic changes, such as the onsets of glacial/interglacial terminations. Calculations for the depth of the gas hydrate stability zone for different paleoceanographic scenarios indicate that increases in the seafloor temperature associated with glacial to interglacial transitions and changes of the position of the MO as a bottom current, could efficiently trigger episodes of gas hydrates dissociation that would result in intense flux of methane rich fluids to shallow sediments or even into the seabottom.

Aerosol transformation and scavenging in stratocumulus clouds LEEHI MAGARTTZ, ALEXANDER KHAIN AND MARK PINSKY Department of the atmospheric Sciences, The Hebrew University of Jerusalem, Israel ([email protected]) A novel Lagrangian model of straocumulus cloud is used for investigation of transformation of aerosol size distribution and aerosol removal from the boundary layer covered by a startocumulus clouds. The moldel consists of about 1500 lagrangian parcels that move within a turbulent –like flow which statistical parameters are taken from observations. The model takes into account processes of diffusion growth, collisions, droplet scavenging and mixing between parcels. The stratocumulus clouds observed during research flights RF01 and Rf07 of the field experiment DYCOMS-II are simulated. The model described diffusion growth of wet aerosols to drops and back to wet aerosols during droplet evaporation. The amount of aereosols in each bin of aerosl/drop size distribution is calculated at each time step. It is shown that aerosols within drops grow by collisions, so that drizzle contains largest aerosols. The rate of aerosol scavenging by drizzle is evaluated. The salinity of drops of different size is calculated. The evaluated rate of aereosol scavenging can be used for estimation of necessry rate of aerosol production in the atmosphere (assuming the balance of the aerosol mass in the atmosphere).


Geochemical zonation in Mirkoh alimirza area, Arasbaran zone, NW Iran A. MAGHSOUDI1, M. YAZDI2, M. MEHRPARTO3 4 AND M. VOSOGHI ABIDENI 1

Faculty of Earth Science, Shahid Behshti University, Tehran, Iran ([email protected]) 2 Faculty of Earth Science, Shahid Behshti University, Iran 3 Geological Survey of Iran (GSI), Tehran, Iran 4 Faculty of Earth Science, Shahid Behshti University, Iran The Mirkoh Ali Mirza area is located in the Arasbaran zone. Arasbaran Zone in NW of iran is a metallogenic province of Cenozoic age. Mineralization in this zone is associated mainly plutonic-volcanic-related porphyry copper, skarn copper-gold and epithermal gold deposits. The major exposed rocks in the area are related to Neogene volcanic and subvolcanic rocks. The local mineralization is structurally controlled, and are localized preferentially in faults and fault intersections. The alteration is dominated by quartz, propylitic, argillic, sericite. Recent geochemical studies within the north of Mirkoh Ali Mirza area shows a distinct lateral metal zonation of gold and base metals which can be used as a guide to exploration of copper porphyry at depth in the adjacent magmatic systems. Chemical variation include Cu as disseminated sulphides and stockwork systems in the center of suvolcanic-volcanic dom. The Au-Ag mineralization shows lateral zonation to outside of the Cu mineralization. The outside chemical zonation continues to Sb, Pb, Zn, Ba and Mn. Data processing of geochemical data shows low but anomalous values for Mo, W, Be and Bi which are associated with the Cu-Au-Ag-Sb mineralization. These elements are sensitive indicators of physicochemical conditions during the ore deposition and therefore can be used as a tool for outlining the center of hydrothermal activity in the sub volcanic body and hydrothermal fluid evolution respect to time and space.

A815

Evaluation study of CCS for the mitigation measure of atmospheric CO2 and ocean acidification by the global carbon cycle model MICHIMASA MAGI Research Institute of Innovative Technology for the Earth, Kizugawadai 9-2, Kizugawa, Kyoto, Japan ([email protected])

Background IPCC AR4 reported that the emission of the anthropogenic Carbon Dioxide (CO2) increase the CO2 concentration in atmosphere after the Industrial Revolution, and increasing of CO2 concentration caused the global warming. Moreover, it is shown that CO2 dissolution into the ocean causes the acidification in the surface layer. The buffering effect of the ocean can suppress the change of the CO2 concentration in the atmosphere. However, the rise of the CO2 concentration in the ocean surface means the pH of seawater decreases. This phenomenon continues until the difference of CO2 partial pressure between the atmosphere and the ocean disappears if the emission of CO2 is stopped. But, the acidification of the ocean progresses as long as it keeps CO2 emission. It is feared that the ocean acidification has crises influence on various organisms and entire ocean ecosystem.

Methods and Results Carbon Capture and Storage (CCS) is one of the mitigation measure technologies of CO2 emission. Famous carbon storage technology of the CCS using ocean region is sub-seabed geological storage (SGS) and dilution type ocean sequestration (DOS). The evaluation and comparison study for atmospheric CO2 decreasing measure and ocean acidification mitigation measure was carried out using 3-dimensional numerical model with ocean circulation model and a global carbon cycle model based on a lower trophic ecosystem model. The results of the simulation study under the several scenarios showed “SGS without leakage is the best as the effect of measures”. And it is suggested that “There is a possibility of suppressing the ocean surface acidification to more effective by combining DOS with SGS”. This study is supported by the CCS project of RITE under the fund from METI.

A816


On lithium isotope systematics and abundances in lunar mare basalts

Why weathering rates differ between the laboratory and the field

T. MAGNA1*, C.R. NEAL2, P.B. TOMASCAK3, B. BOURDON4, F. OBERLI4 AND J.M.D. DAY5

KATE MAHER1, CARL I. STEEFEL2 3 AND ART F. WHITE

Univ. Münster, Germany (*correspondence, [email protected]) 2 Univ. Notre Dame, USA ([email protected]) 3 SUNY Oswego, USA ([email protected]) 4 ETH Zürich, Switzerland ([email protected], [email protected]) 5 Univ. Maryland, USA ([email protected]) Recent studies of lunar mare basalts and volcanic glasses [1,2] have revealed resolvable δ7Li differences between the melt products of low-Ti olivine-orthopyroxene-rich cumulates and high-Ti clinopyroxene-dominated lithologies formed after extensive crystallization of the lunar magma ocean (LMO), where the high-Ti basalts carry a higher δ7Li signature. To more rigorously assess δ7Li variations in the Moon, we have analyzed a variety of lunar low- and high-Ti mare basalts from the Apollo 11, 12, 14, 15 and 17 sites for their Li abundances and isotope compositions. The new data indicate broad δ7Li homogeneity for the suite as a whole, with a few subtypes clearly deviating from the main field, and only subtle differences between low- and high-Ti basalts. High-K A-type basalts from the A11 site show a significant imprint of Li-rich material, likely consistent with addition of a KREEP component [3]. This is further corroborated by our new estimate of KREEP δ7Li and Li abundances derived from KREEP basalt 15386 and impact melt 14310. C-type basalts from the A17 site have consistently higher δ7Li than all other mare basalts, which may relate to metasomatic overprint by alkali-rich fluids [4], rather than the effect of clinopyroxene accumulation [1]. The δ7Li variability of A17 high-Ti mare basalts provides further evidence for their origin from heterogeneous mantle sources [5]. Subtle δ7Li fluctuations within individual A12 flows (olivine, pigeonite and ilmenite basalts) can be explained by fractional crystallization of olivine (± pigeonite). Our new results for olivine-normative A15 basalts (ONBs) further underscore their differences with A15 quartznormative basalts (QNBs) [1], possibly indicating gradual evolution of their common source via accumulation of olivine in ONBs and plagioclase accumulation in QNBs [6]. [1] Magna et al. (2006) Earth Planet. Sci. Lett. 243, 336; [2] Day et al. (2008) Lunar Planet. Sci. Conf. XXXIX, #1072; [3] Jerde et al. (1994) Geochim. Cosmochim. Acta 58, 515; [4] Neal et al. (1990) Lunar Planet. Sci. Conf. XXI, 855; [5] Rhodes et al. (1976) Lunar Planet. Sci. Conf. 7th; 1467; [6] Schnare et al. (2008) Geochim. Cosmochim. Acta 72, 2556.

1

School of Earth Sciences, Stanford University (*correspondence: [email protected]) 2 Earth Sciences Division, Berkeley National Laboratory ([email protected]) 3 U.S. Geological Survey, Menlo Park, CA ([email protected]) In order to understand how experimentally-determined rate constants and kinetic rate laws can be extrapolated to capture the overall rates and chemical evolution of natural systems, a reactive transport model was used to fit the aqueous chemistry, mineral saturation state and solid elemental and mineral abundances 1.4 Petroleum Type Organofacies from a well-studied PNA High Wax PNA Low Wax chronosequence at Paraffinic Gas + Condensate Santa Cruz, CA. 1.2 Rate constants were initially calculated 1 for the primary dissolving minerals (albite and K- 0.8 feldspar) and the intermediate low late gas potential dominant late gas potential late gas ratio (1) (LGR1) precipitating 0.6 mineral (kaolinite) 0.45 0.5 0.55 using a simple linear TST approach. The intrinsic rate constant for the linear TST model was found to be 2 orders of magnitude smaller than the experimentally determined laboratory rate constant, even though the effect of kaolinite precipitation on the fluid saturation state was accounted for. The ability of the linear reference model to match the available data was compared to simulations that used experimentally-derived rate constants and rate laws with a non-linear dependence on the approach to equilibrium. When a non-linear dependence on the approach to equilibrium was considered using alternative rate law formulations, we found that the calculated rate constants were within error of experimental rate constants for the same fit to the data. These results suggest that the discrepancy between experimentally and field-calculated rates is not purely a result of close-to-equilibrium dissolution in natural systems, but depends on the particular form of the rate law as reaction rates approach equilibrium and on the identity and solubility of precipitating minerals. late gas ratio (2) (LGR2)

1

high late gas potential

0.6


High temperature methane as an unconventional gas source

Climate impacts on annual-average airborne particle source contributions in California

N. MAHLSTEDT* AND B. HORSFIELD

ABDULLAH MAHMUD1, ZHAN ZHAO2, MARK HIXSON1, JIANLIN HU2, SHU-HUA CHEN2 1 AND MICHAEL J. KLEEMAN *

GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany (*correspondence:[email protected])

Late gas potential evaluation In this study we consider in detail which source rocks possess a late gas potential in general. Late dry gas generation can be expected for organic matter with R0 > 2.0% and for geologic temperatures in excess of 200°C [1, 2]. This may, in addition to the cracking of unexpelled oil, contribute significantly to the accumulation of thermogenic gas in gas shales and coal seams.

Figure 1: Late gas potentials of analysed source rocks, based upon C1-5 and C6+ MSSV-pyrolysis yields at 560°C and 700°C (see equation 1 and 2 for the late gas ratios definition). Equations: Late gas ratios (MSSV-pyrolysis)

(1)

(2)

Discussion of Results High late gas potentials (LGR1 > 0.55) are mainly seen for terrestrial influenced type III to type II/III shales and coals. The late gas yield cannot be attributed to secondary cracking of C6+ compounds alone (LGR2 > 1) but is related to the decomposition of a C 700°C neoformed LGR1 = 560°C 1−5 700°C C1−5 + C1−5 recombination residue generated at lower

LGR2 =

°C C1700 −5 °C °C °C C1560 + (C 6560 − C 6700 ) × 0.7 −5 + +

maturation levels [1, 2]. [1] Erdmann & Horsfield (2006), Geochim. Cosmochim. Acta 70, 3943-3956. [2] Dieckmann et al. (2006), Mar. Pet. Geol. 23, 183-199.

A817

1

Department of Civil and Environmental Engineering, University of California at Davis, One Shields Avenue, Davis, CA 95616. (*correspondence: [email protected]) 2 Department of Land, Air, and Water Resources, University of California at Davis, One Shields Avenue, Davis, CA 95616 California has one of the worst particulate air pollution problems in the United States with some estimates predicting more than 5000 premature deaths each year attributed to air pollution. Climate change will modify weather patterns in California with unknown consequences for airborne particulate matter (PM). Previous down-scaling exercises carried out for the entire United States have typically not resolved the details associated with California’s mountainvalley topography and mixture of urban-rural emissions characteristics. Those detailed studies specifically carried out for California have identified strong effects on PM acting in opposite directions making the net prediction for climate effects on PM somewhat uncertain. More research is needed to reduce this uncertainty so that we can truly understand climate impacts on PM and public health. The objective of this research is to predict climate change effects on annual average concentrations of particulate matter (PM) in California with sufficient resolution to capture the details of California’s air basins. Particular emphasis will be placed on trends in source contributions to PM in the presence of climate change. Business-as-usual scenarios generated by the Parallel Climate Model (PCM) will be downscaled to 4km meteorology using the Weather Research Forecast (WRF) model. The CIT/UCD source-oriented photochemical air quality model will be employed to predict PM source contributions throughout the entire state of California. The modeled annual average total and speciated PM concentrations for the future (2047-2049) and the present-day (2004-2006) periods will be compared to determine climate change effects. The results from this study will improve our understanding of global climate change effects on PM source contributions in California.

A818


Combined FISH, µ-XRF and SEM analysis to examine microbe-metal interactions on root surfaces R.M. MAIER*, J. CHOROVER, S.L. IVERSON AND S.M. HAYES Department of Soil, Water and Environmental Science, University of Arizona, Tucsion, AZ 85721, USA (*correspondence: [email protected]) Metalliferous mine tailings in arid regions pose a significant health risk to proximal populations because they are prone to wind-borne dispersion and water erosion. The problems are extensive and persistent as impacted sites lack normal soil stabilization processes. Phytostabilization is the revegetation of mine tailings to ameliorate these issues with the goal of root zone metal accumulation to avoid metals from entering the food chain through above-ground biomass. The role of plant roots and microbes in promoting mineral dissolution-precipitation reactions and associated metal sequestration is an active area of research, but little is known about reaction trajectories and changes in particle-scale metal speciation of plant-tailings systems, owing largely to their geochemical heterogeneity and microbial complexity. Since the form or speciation of a metal controls its bioavailability and toxicity, research that probes coupling between metal speciation and microbial dynamics in response to phytostabilization is needed. The goal of this research is to develop methodology to combine the use of fluorescent in situ hybridization (FISH), microfocused-x-ray fluorescence (uXRF), and scanning electron microscopy (SEM) to assess the spatial heterogeneity and relationship between bacterial colonization (FISH) and metal distribution (u-XRF) on root surfaces of plants grown in metalliferous tailings. Initial data will be presented that show FISH, u-XRF, and SEM can be technically combined to examine the same root sample. These initial results visually co-localize bacteria with metal precipitates on root surfaces.

The Bluebush Zinc Prospect, NW Queensland: Multiple base metal mineralising events and a record of fluctuating redox conditions in late Palaeoproterozoic seas RODNEY C. MAIER AND PETER J. MCGOLDRICK* Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Tas 7001, Australia (*correspondence: [email protected]) The Bluebush Zinc Prospect is a huge accumulation of weakly Zn mineralized bedded pyrite in sedimentary rocks of late Palaeproterozoic age. It is obscured by Mesozoic sedimentary cover some 55 – 350 m thick, but geophysical surveys indicate that pyrite-rich stratigraphy occupies an area at least 25 x 10 km. Anomalous Zn grades (0.5 – 1wt%) are present over intervals up to a few tens of metre thick in both reduced and oxidised rocks. The sequence is conformable, laterally continuous, and composed of organic-rich silt, shale, and chemical sediments, significantly modified by diagenetic and hydrothermal alteration. Zinc mineralization occurs over 600 m of stratigraphy comprising a lower (reduced) facies that is highly pyritic and and contains distinctive ‘fluidal’ pyrite and carbonate textures. This unit is overlain by thick-bedded (barren) mass flow deposits, which are in turn overlain by a distinctive green-pink laminated and nodular (oxidised) facies containing magnetite (minor hematite) and chlorite. The oxidised facies is Zn mineralized and passes gradationally upwards into barren siltstones and pyritic, carbonaceous shales. Sulfide textures and pyrite trace element chemistry support a multi-stage (diagenetic) origin for the Zn mineralisation [1]. The redox changes manifested in the sedimentary facies variations can be accounted for in terms of relative sea level changes over time [2]. However, we will present new S isotope data from pyrite that suggest high productivity (perhaps associated with a brine pool) had role in producing the lower pyritc facies, whereas, the upper pyritic unit formed in a more ‘normal’ Proterozoic deep marine setting. [1] Maier, R.C.(2006) CODES Ores in Sediments Symposium Unpublished Extended Abstracts. [2] Maier, R.C. (2009) PhD University of Tasmania In prep.


Environmental constrains on microbial methane oxidation activity and community structure in Gulf of Cadiz mud volcanoes L. MAIGNIEN, N. BOON AND THE RV JAMES COOK JC10 SHIPBOARD SCIENTIFIC PARTY LabMET, Ghent University, Belgium (*correspondence: [email protected]) In the Gulf of Cadiz, mud volcanism is supporting the development of cold seep ecosystems based on the Anoxic Oxidation of Methane (AOM). Due to the variety of eruptive processes and geochemical settings, these mud volcanoes (mv’s) constitute an ideal natural laboratory to study the AOM microbial community ecology. During the RV James Cook JC10 cruise, we targeted three mv’s, with the aim to measure methane turnover, its potential controls and associated microbial diversity. Sulphate reduction and methane oxidation activities were measured using radio-labelled substrates immediately upon sediment recovery, whereas diversity survey was carried by mean 16s rDNA libraries. Typical Methane and sulphate gradients associated with AOM were present in the sediment except at MERCATOR mv where dissolution of gypsum (CaSO4) maintained high sulphate concentration along the entire core. The lowest activities were measured at MERCATOR mv, where salt concentration up to 10 times sweater concentration may inhibit the AOM reaction. At DARWIN mv, discrete AOM near-surface hot-spots sampled with the Remote Operated Vehicle ISIS resulted in highest activities and revealed the heterogeneous nature of this mv. Archaeal and bacterial 16S rRNA gene clone libraries showed that AOM communities differed considerably between these three mv' s. At DARWIN and CARLOS RIBEIRO mv’s, AOM communities were relatively diverse and dominated by ANME-2, ANME-3 and associated sulfate-reducing bacterial phylotypes, whereas AOM diversity at MERCATOR was much lower and dominated by the ANME-1b phylotype. Overall, these results demonstrate the influence of several environmental parameters such as sediment geochemistry, seep relocalization following carbonate crust development and methane flux on the microbial activity and community structure at these cold seep sites.

A819

Study of petrology and magmatic evolutions in west part of Shir Kuh batholite SH. MAKVANDI1, N. RASHID NEJAD2 3 AND F. MASOUDI 1

Tarbiat Modares University, National geosciences database of Iran 2 Tarbiat Modares University 3 Tarbiat Moalem University Western part of Shirkuh Granitoid Batholite is a peraluminous multiphase plutonic complex based on geochemistry and petrography studies. In this complex considered as S-type granites due to the presence of mica and garnet, silica range (65-75%), high A/CNK ratio, calc-alkaline characters and syncollisional volcanic arc setting. At the same time, younger phases are belived as I-type bodies because of their petrography, major elements, oxide trends and spiky spider diagrams. Pertite texture is resulted in high-K replacement processes. This texture is the most common texture in Shirkuh Complex which is along to graphic overgrowth textures indicates that this complex is a subsolvus granite, crystallized in the high vapor pressure conditions. Furthermore, geochemistry analysis and petrography represent Hydrothermal Fluids invasion and metasomatic origin at least in some parts of this Batholite.


A820

Geochemical dissection of a kimberlite: What makes up a whole rock analysis? 1

1

1

J. MALARKEY *, D.G. PEARSON , J.P. DAVIDSON , G.M. NOWELL1, B. KJARSGAARD2 AND C.J. OTTLEY1

Unravelling redox processes in mantle wedge peridotites N. MALASPINA*, S. POLI AND P. FUMAGALLI Dipartimento di Scienze della Terra, University of Milano, Italy (*correspondence: [email protected])

1

NCIET, Durham University, Durham DH1 3LE, UK (*correspondence: [email protected]) 2 Geological Survey of Canada, Ottawa, Canada, K1A OE8 The elemental and isotopic composition of ‘primary’ kimberlite magma has been the subject of considerable debate for decades. The frequent occurrence of variably sized crustal fragments within hypabyssal and volcaniclastic kimberlite is a clear indication of the potential importance of crustal contamination in modifying the composition of the kimberlite magma. We present a trace element and isotopic study of multiple mineral phases from a kimberlite. Our objective is to see if different phases record different stages of crustal contamination in the evolving kimberlite and to assess which phases are most likely to give the best information on potential source regions. We have analysed phlogopite, perovskite, olivine and calcite from a Group I kimberlite from Jos, Somerset Island, Nunavut. These results are compared with olivine, phlogopite, perovskite and apatite picked from a parallel study of an olivine melilitite from Saltpetre Kop (SPK), S. Africa. Melilitites are less obviously affected by crustal contamination and are generally less altered by low-T processes but contain a similar suite of minerals to kimberlite and therefore provide a simple analogue. The minerals were leached and then processed for Sr and Nd isotopes and trace elements. Leachates were also collected. Preliminary Sr isotope data from the melilitite confirm that olivine and perovskite have similar 87Sr/86Sri ratios to the whole rock; while the later crytsallising phases, apatite and phlogopite, show increasingly more radiogenic values. Together they define a reasonable Rb-Sr isochron age of ~77±3.4Ma close to the published emplacement age (72.576.8Ma, [1]), which effectively rules out any significant progressive crustal assimilation. Preliminary results from the Jos kimberlite are more complex and not consistent with closed system behaviour as with SPK. Variations in initial 87Sr/86Sr both within and between the different mineral phases so far analysed can be explained by a combination of factors that include progressive crustal contamination and source heterogeneity. [1] Duncan et al (1978), Geological Magazine, 115, 317-396

Oxygen fugacity (fO2) is an important parameter in determining the relative stabilities of phase assemblages. Despite a number of studies have been devoted to determine the redox state of low pressure assemblages in the mantle system, the fO2 of supra-subduction mantle wedge is still poorly investigated. An essential input for fO2 estimates is represented by the determination of Fe2+-Fe3+ content of key mantle minerals such as garnet, which can be measured by the "flank method" technique with electron microprobe. As case studies, we selected samples of orogenic peridotites from the ultrahigh pressure Sulu belt (Eastern China) and from the Ulten Zone (Italian Alps) corresponding to slices of metasomatised mantle wedge sampled at different depths. They show phlogopite + magnesite and amphibole in equilibrium with olivine, orthopyroxene and Fe3+-bearing garnet. The “flank method” measurements indicate that these pyrope-rich garnets contain Fe3+/ΣFe up to 0.12–0.14. For peridotite mineral assemblages fO2 can be evaluated from equilibria involving Fe3+-garnet component Fe2+3Fe3+2Si3O12 on the basis of Fe3+–Al substitution on the octahedral site, which is sensitive to the garnet oxidation state. We modelled a non-ideal mixing of Al and Fe3+ on the octahedral site, and a non-ideal mixing on the dodecahedral site, with a symmetric regular solution model for reciprocal solid solutions of Ca– Fe2+–Mg–Al–Fe3+-garnet. This enabled us to calculate fO2 of garnet, given the presence of Fe3+. Our results indicate that the Sulu and Ulten peridotites record high oxygen fugacities (FMQ÷FMQ+2) compared with peridotite xenoliths from subcratonic mantle equilibrated at similar pressure conditions. The determination of fO2 of these C–H-bearing garnet peridotites enabled us to estimate the speciation of C–O–H metasomatic fluids derived from the subducting slab, which result enriched in CO2. These data might suggest that the relatively high fO2 of these mantle wedge peridotites corresponds to a bulk oxidation due to the influx of slab-derived metasomatic fluids. However, we demonstrated that the variation of fO2 in multicomponent systems is not a simple increasing monotonic function of the oxygen content in the compositional space. The evaluation of fO2 of metasomatised mantle wedge peridotites, representing the oxygen chemical potential µO2, therefore provides the first step to unravel the relationships between µO2 and the metasomatic phase assemblages in multicomponent mantle systems.


Structure and dynamics of water surface in the helium and argon atmosphere: Computer simulation G.G. MALENKOV Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Moscow, Russia ([email protected]) Molecular dynamics computer simulation of water films about 40 Å thick was performed. Virtual temperature was about 300 K. Simulated systems contained several thousands of water molecules and up to two hundreds of helium or argon atoms. Both surfaces of the film are very rough. Diffusion coefficient of the surface molecules is noticeably greater than those of the molecules in central region of the film. Diffusion coefficients in the films under the pressure of noble gases are somewhat lower than in the films which are in the equilibrium with water vapour in the absence of any other component. Diffusion of the surface molecules is almost isotropic. Surface molecules form fewer hydrogen bonds than molecules in the bulk water and in centre of the film. Distribution coefficients of the gas atoms between the two phases are in qualitative agreement with experimental data on the solubility of these gases at corresponding temperature and pressure. Surrounding of argon atoms by water molecules does not resemble structure of the clathrate hydrates.

A821

Isotopic markers in wines from Douro region, Portugal V. MALHEIRO1, P. FAVAS1, M. GOMES1 2 AND S. RIBEIRO 1

Dep. of Geology, UTAD, Ap.1013, 5000-801 Vila Real, Portugal ([email protected], [email protected], [email protected]) 2 Dep. of Geosciences, University of Aveiro, 3810-193, Aveiro, Portugal ([email protected]) Food safety is one of Europe’s priorities and is becoming a Worldwide demand, due to the mobility of people and provisions. Food supplies traceability must be insured from farmers to consumers. Discrimination of wines from particular regions through trace elements is based on a presumption that its content results essentially from rock to soil and from this to grape. Several works have been developed on isotopic markers as tools towards the geographical authenticity of wines. In order to better understand chemical elements translocation along rock-soil-vine-wine system Sr and 87Sr/86Sr ratio behaviours were studied in vine. Their use as a possible fingerprint of the Douro Controlled Origin of Denomination was evaluated. The study was based on the characterization of two distinct geological regions, Carrazeda de Ansiães (granite) and Alijó/Sabrosa (schist), situated in the Douro Region. All rock, soil, vine organs and red wines were collected in these zones.

Figure 1: Average Sr content and standard derivation by sample. 87

Sr/86Sr Granite Schist

Rock 0.770011 0.739819

Soil 0.779225 0.740815

Grape (must) 0.71799 0.716083

Wine 0.719199 0.718108

Table 1: Rocks, soils, musts and wines 87Sr/86Sr ratio. The values obtained in this study and in others, including multielement analysis could be useful in wine discrimination according to their geographical provenience and to detect/prevent frauds. The Sr value could be used as fingerprints in the origins of wines, but the wine isotopic ratio is probably controlled by other factors, such as rain water, which need to be studied.

A822


Distinct PGM assemblages in a mantle tectonite at Unst: Evidence for robustness of Os-isotope system

Isotopic fractionation of Sn due to methylation and demethylation reactions in aqueous solution

K.N. MALITCH1*, R.A. LORD2, T.C. MEISEL3, H.M. PRICHARD4 AND I.N. KAPITONOV1

D. MALINOVSKIY*, F. VANHAECKE AND L. MOENS

1

Russian Geological Research Inst., 199106, St.Petersburg, Russia (*correspondence: [email protected]) 2 Univ. of Teesside, Middlesbrough, UK ([email protected]) 3 Univ. of Leoben, Leoben 8700, Austria ([email protected]) 4 Univ. of Cardiff, Cardiff CF10 3YE, Wales, UK ([email protected]) This study presents the first extensive data set of Os isotopic compositions of ‘primary’ and ‘secondary’ platinumgroup mineral (PGM) assemblages derived from ophiolitetype ultramafic complex at Unst (Shetland Islands, UK), considered to form at ~473 Ma. The study employed a multitechnique approach and utilized a number of analytical techniques, including electron microprobe analysis, ID ICPMS after high pressure acid digestion and LA MC-ICP-MS. Two distinct PGM assemblages characterize an isolated chromitite pod in dunite at Harold’s Grave, about 0.5 km below the transition zone harzburgite and petrological Moho. A ‘primary’ magmatic euhedrally shaped (up to 55 µm in size) PGM assemblage mainly composed of laurite and osmian iridium occur as composite inclusions in chromite. A ‘secondary’ subeuhedral to anhedral PGM assemblage (up to 300 µm), dominated by laurite, Os-rich laurite, irarsite, osmium and Ru-penlandite, has been documented in cracks filled by chlorite or serpentine, interstitially to chromite grains. This alteration assemblage is likely to reflect processes such as in situ serpentinisation, alteration during emplacement or regional greenschist metamorphism. Whole-rock PGE concentrations give negatively sloped chondrite-normalized PGE patterns, typical of podiform chromitite, where IPGE prevail over PPGE. The osmium isotope results identify similar ‘unradiogenic’ 187Os/188Os values for ‘primary’ and ‘secondary’ PGM assemblages (e.g., 0.12043-12558 with median of 0.12441, n=33 and 0.123450.12763, median=0.12448 and n=59, respectively), being within uncertainty of the chromitite composition (0.1240±0.0006). This implies that the whole-rock Os isotope budget is largely controlled by laurite-dominant assemblages, supporting the conclusion that the ‘secondary’ PGM assemblage inherited the subchondritic osmium isotope signature of the ‘primary’ PGM. No evidence for other source contributions (e.g., suprachondritic) during later thermal events, as frequently invoked, has been observed.

Department of Analytical Chemistry, University of Gent, Gent 9000, Belgium (*correspondence: [email protected]) Laboratory experiments, modeling the methylation of inorganic Sn(II) by methylcobalamin and the decomposition of methyltin under irradiation with UV light in aqueous solution, have been performed. Methyltin has been separated from inorganic Sn using ion-exchange chromatography and subjected to Sn isotope ratio measurements by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The methylation of Sn(II) in the dark was accompanied by mass-dependent Sn isotopic fractionation, which resulted in preferential partitioning of the lighter Sn isotopes into the organic phase, with a shift of ∼0.6±0.1‰ in terms of δ124Sn/116Sn between methylated and inorganic Sn. The methylation of Sn(II) by methylcobalamin under UV irradiation resulted in the accelerated formation of methyltin in the beginning of the process, but was followed by the photolytic degradation of methyltin until its complete mineralization. The photolytic degradation of methyltin in the presence of methylcobalamin and inorganic Sn(II) was slower than that of pure solutions of commercially obtained monomethyltin. This is attributed to the methylating action of methyl radicals produced from photolytically decomposing methylcobalamin. Both synthesis and decomposition of methyltin under UV irradiation were accompanied by both mass-dependent and mass-independent Sn isotopic fractionation, with the latter due to the magnetic isotope effect. As a result of this, the lighter Sn isotopes preferentially partition into reaction products, while the odd isotopes, 117Sn and 119Sn, are selectively enriched relative to the other isotopes in the starting molecules. The extent of the observed variations in the isotopic composition of Sn is larger than that documented previously for geological and archeological samples. These results indicate that Sn isotopic fractionation between various chemical forms of Sn in the natural aquatic systems may be significant and can provide new insights into the biogeochemical cycling of the element.


A823

Urban socio-economic factors affect the isotopic composition of fish muscle

U/Pb dating of zircons from the lower crustal xenoliths from Siberian kimberlites

E.M. MALKIN, E.B. PEEBLES AND D.J. HOLLANDER*

V.G. MALKOVETS1*, E.A. BELOUSOVA2, W.L. GRIFFIN2, L.V. BUZLUKOVA1, V.S. SHATSKY1, S.Y. O’REILLY2 AND N.P. POKHILENKO1

University of South Florida, College of Marine Science, St. Petersburg, FL 33701 (*correspondence: [email protected]) The global phenomenon of burgeoning coastal population growth and urbanization has led to coastal ecosystem deterioration, prompting policy-makers to set limits on freshwater withdrawals and labile nutrient loads. Contrasting land use and nutrient sources in Florida watersheds provide many opportunities to isotopically trace the effects of urbanization and local hydrology on biogeochemical nitrogen pathways. Using data collected during rainy Florida summers, mechanistic and empirical linear regression models can accurately predict the stable nitrogen isotopic composition (δ15N) of estuarine fish muscle based on the amount of agricultural and natural land cover in the estuarine watershed. In contrast, similar efforts during the spring dry season were initially unsuccessful. During rainy summers, when hydrologic land-water connectivity is enhanced by daily afternoon thundershowers and a high water table, nutrients in the watershed become closely linked to estuarine food webs, causing fish isotopes to become highly predictable—except in heavily urbanized areas. Upon closer examination, socioeconomic factors within these urbanized areas were found to have strong predictive power during both rainy and dry seasons. A separate empirical model for urban areas was successful in predicting fish δ15N based on a combination of septic tank density, human population density, and percent of population below poverty level. The isotopic influences of septic tank and population density are well understood, whereas the relationship with poverty is less obvious. We suggest poverty correlates with leaky plumbing and a reduced tendency to use fertilizer on lawns and ornamental plants. In general, we have found that our models fail in highly disturbed ecosystems and suspect that model deviation could be a measure of ecosystem deterioration in future studies.

1

Institute of Geology and Mineralogy SB RAS, Novosibirsk, 630090, Russia (*correspondence: [email protected]) 2 GEMOC National Key Centre, Macquarie University, Sydney, 2109, Australia Zircons from seven lower crustal xenoliths from Siberian kinberlites have been dated in situ by U/Pb LAM-ICP-MS at the GEMOC National Key Centre, Macquarie University, Australia. The suite of studied samples comprises two granulites from the Udachnaya pipe and one granulite from the Leningradskaya pipe, (Daldyn kimberlite field), one granulite from the Yubileinaya pipe and three shists from the Komsomol’skaya pipe, (Alakit field). Thirty eight zircon grains were extracted and analyzed from the granulite xenolith Ud-01-44 (Udachnaya). Most of the zircons give 207Pb/206Pb ages of 1.89 Ga and two grains give 2.5 Ga. Only four zircons have been found in the granulite xenolith Ud-01-66 (Udachnaya). They give a 207 Pb/206Pb age of 1.79 Ga. Twenty zircon grains from granulite xenolith L-02-9 from the Leningradskaya pipe give a 207 Pb/206Pb age of 1.9 Ga. Six zircon grains from the granulite xenolith Yb-02-27 (Yubileinaya pipe) give a 207Pb/206Pb age of 1.86 Ga. Twelve zircon grains from the shist xenolith K-3-02 (Komsomol’skaya) give a 207Pb/206Pb age of 1.89 Ga. Seventeen zircon grains from the shist xenolith K-69-02 (Komsomol’skaya) give a 207Pb/206Pb age of 1.9 Ga. Three other grains give 2.9, 2.4, and 2.3 Ga. Nineteen zircon grains from the shist xenolith K-45-02 from the Komsomol’skaya pipe give a 207Pb/206Pb age of 1.84 Ga. Two grains give 2.3 Ga and one grain give 2.46 Ga. Xenoliths of granulites and shists from the Paleozoic kimberlites provide the timing of major periods of lower crust formation in the Siberian craton in Archean and Proterozoic time. The Paleoproterozoic ages around 1.8-1.9 Ga correspond to a period of crustal reworking, and the collision between separate blocks of the craton, during the final assembly of the Siberian craton [1,2]. [1] Rosen et al. (1994) In: Condie, K.C. (ed.), Archean Crustal Evolution, 411-459. [2] Smelov and Timofeev (2007) Gond. Research 12, 279-288.


A824

Lateritic sheet air

X-ray views of the defect structure and chemistry of environmental nanoparticles

V.I. MAMEDOV AND S.A. VOROBJOV Geoprospects Ltd ( [email protected]) Lateritic sheet air has been first tested for O2, CO2, CO, and CH4 concentrations. The tests were performed at a bauxite deposit situated in northwest Guinea. The deposit area includes step-like hills (mesas) and their gentle slopes with altitudes 260 to 180 m. The gas concentrations were measured in 35 auger holes intersecting the local ground water table (depths 10 to 15 m) and belonging to exploration profiles crossing several relief and geological zones. The dynamics of gas exchange between laterites and atmosphere was monitored in a number of profiles with twohour periodicity. Gas concentrations were measured by a gas analyzer OLDHAM COM2100 with sensors for CO2 (sensitivity 0.1 vol. %), O2 (sensitivity 0.1 vol. %), CO (sensitivity 1 ppm), and CH4 (sensitivity 10 ppm). The air monitoring was made for the whole length of each borehole. It is found that O2 concentration decreases with depth from 20.8% at borehole collar to 5% at the ground water table, with CO2 concentration increasing simultaneously from 0.1 to 10%. The uppermost 3- to 4-m interval represents the zone of intense gas exchange between the laterites and the Earth’s atmosphere, with a gentle change gradient of the gas concentrations. On the contrary, the underlying 2- to 3-m interval shows a jumping change gradient of the gas concentrations. Deeper, down to the ground water table, the gas concentrations remain almost constant. Thickness of the zone of intense gas exchange is decreasing in daytime and increasing at night. Rains cause its abrupt increase. However, these fluctuations are not accompanied by any considerable changes in O2 and CO2 concentrations at the ground water table. High CO (20-300 ppm) is most typical of boreholes drilled on slopes. Its concentration is gradually increasing to maximum value at the middle of vertical profile and then is decreasing with depth to the half-peak. CH4 peaks (10-20 ppm) coincide with CO peaks. The gas distribution data of boreholes allow the conclusion that the vaporization scale in lateritic sheets is considerable. The gaseous dynamics of boreholes allows the assumption that CO2 and CO are produced by the reaction between the organic compounds present in lateritic sheets and the free oxygen transported from the Earth’s atmosphere into the lateritic sheets with rainwater

A. MANCEAU1, B. LANSON1, M.A. MARCUS2, S. SKANTHAKUMAR3 AND L. SODERHOLM3 1

LGCA, Univ. J. Fourier and CNRS, Grenoble, France ALS, LBNL, Berkeley, CA 94720, USA 3 CSE, ANL, Argonne, IL 60439, USA 2

Major goals of environmental science are to control mobility of toxic elements and to remediate contaminated soils, sediments, and subsurface waters. These goals cannot be met without first having in hand a fundamental understanding of the elemental composition, defect structure, and surface properties of environmental nanoparticles. Key problems are their low dimensionality, short-range order and high density of defects, the multiplicity of reactive surface sites and bonding mechanisms of impurities, and the partitioning of elements into coexisting organic and inorganic phases. In most cases, the information sought can be obtained by application of synergistic synchrotron-based X-ray techniques, including microfluorescence (micro-SRXF), microdiffraction (microXRD), high-energy scattering (HEXS), and microspectroscopy (micro-EXAFS), as well as data modelling with meaningful structure models. In this approach, micro-SRXF is used to map trace contaminants among coexisting constituents in a natural matrix, thus determining their distribution and relative abundance with unrivalled sensitivity. Then, micro-XRD, complemented by powder XRD and HEXS, is employed to identify nanocrystalline minerals and, more importantly, to determine the nature of structural and chemical defects (stacking faults, cationic and anionic vacancies and occupancies, site occupation of impurities, stoichiometry) through modelling of their scattering properties. Finally, micro-EXAFS gives the uptake and complexation mechanism of trace contaminants by individual constituents. Since the distribution of trace elements is heterogeneous on nanometer to micrometer length scales and nanoparticles are generally aggregated in environmental systems, the combination of these three microscopic techniques provides just the tools needed to scrutinize the nature and fundamental properties of environmental matter. This new kind of hybridization of experimental and modelling approaches to the characterization of natural nanoparticles will be illustrated with examples that show its potential for expanding our knowledge in environmental science.


Proton binding constants for natural organic matter

Study on district level emission of carbonaceous aerosol from biofuels used in rural sector as energy over Indo Gangetic plain

A. MANCEAU1, A. MATYNIA1, T. LENOIR1, B. CAUSSE2,3 2 AND L. SPADINI 1

LGCA, Univ. J. Fourier and CNRS, Grenoble, France LGIT, Univ. J. Fourier and CNRS, Grenoble, France 3 LSE-ENTPE, Univ. Lyon, Vaulx en Velin, France 2

Humic (HA) and fulvic (FA) acids are complex and heterogeneous assemblages of dominantly carboxyl (COOH) and phenol (ph-OH) polyelectrolyte groups issued from the breakdown of bacterial, algal, and/or higher plant organic material. The acid-base equilibria of these groups, which control their ion binding properties, is measured usually by potentiometric titration and expressed numerically by the two proton binding constants log KH,COOH and log KH,ph-OH, and the two associated site densities QH,COOH and QH,ph-OH. The mean intrinsic proton binding constants derived from titration curve fitting with the NICA-Donnan model are log KH,COOH = 3.09 ± 0.51 for HA and 2.65 ± 0.43 for FA, and log KH,ph-OH = 7.98 ± 0.96 for HA and 8.60 ± 0.83 for FA [1]. The high acidity of carboxyl groups and the differences between HA and FA either are real or within the uncertainty and accuracy of titration modeling. To address this question, average log KHi values were calculated semi-empirically from structure models of FA and HA, and then used to simulate titration data from Sphagnum sp. and Carex sp. peats. Predicted constants are log KH,COOH = 3.73 ± 0.13 for HA and 3.80 ± 0.20 for FA, and log KH,ph-OH = 9.83 ± 0.23 for HA and 9.87 ± 0.31 for FA, and reproduce data as well as the generic NICA-Donnan constants. Principal component analysis of 47 published proton titration curves shows that the dataset contains six independent parameters, while eight are optimized in the NICA-Donnan model. Results also show that the dataset can be fit using variable combinations of {log KH,i, QH,i} numerical values. Therefore, differences in proton binding constants and site densities reported in the literature result partly from the use of loosely constrained data fits. An analytical procedure is proposed to increase the robustness of acid-base parameters derived from titration measurements for organic matter. [1] Milne C. J., Kinniburgh D. G. and Tipping E. (2001) Environ. Sci. Technol. 35, 2049-2059.

A825

T.K. MANDAL1*, TRAILOKYA SAUD1, MOHIT SAXENA1, R.P. BHATNAGAR1, DHARAM PAL2, RANU GADI2, RISHU GAUTAM1, SUDHIR SHARMA1, ALOK MUKHERJEE1 AND A. DATTA 1

Radio and Atmospheric Sciences Division, National Physical Laboratory, New Delhi, India ([email protected]) 2 Guru Govid Indra Prastha University, Kashmiree Gate, New Delhi, India ([email protected], [email protected]) Indo Gangetic plain is major emitter of pollutants in India. To our best knowledge, for the first time, emission factor of carbonaceous aerosol from biofuels used by rural sector for energy, are presented at district level in all states (Punjab, Haryana, Uttar Pradesh, Bihar, Jharkhand, Utttarakhand, Himachal Pradesh, West Bengal, Delhi, Rajasthan) of Indo Gangetic Plain. Distribution of biofuels uses by rural sector as energy show that cow dung is mostly used as energy among other biofuels (fuel wood, crop residue). Emission factor are determined by total burning (pyrolysis, flaming and smoldering) of those biofuel samples in the laboratory. Cow dung represents major emitter of organic carbon in this region. Samples were collected at district level from different rural areas of all states of IG plain to get the real picture of the biomass used in these areas by interrogating with local people. Demographic data were also collected to estimate the budget. Burning of those samples is being carried out in the laboratory and emission factor of carbonaceous aerosol are determined. The study revealed that in the rural sector of north India cow-dung cake is the major biomass used as the fuel for cooking purpose. Uttar Pradesh has the largest variability among the biomass use. Further, in situ study of the biomass materials collected from the sampling locations will help to develop the mitigation strategy to reduce the atmospheric pollution. Contribution of dung cake in organic carbon is effectively more due to high emission factor (Table-1) Fuel EC (g/kg) OC (g/kg) Fuel wood Morus sp (Shahtoot) Acacia sp (Keekar) Brassica sp (Sarso) Zizyphus sp (Ber)

~0.05 ~0.07 ~0.1 ~0.06

~0.51 ~1.07 ~4.48 ~0.95

Dung Cake

~0.07

~0.51

Table 1: Emission factor for OC and EC.

A826


Sea salt concentrations over Europe: Measurements and modelling A.M.M. MANDERS*, M. JOZWICKA AND M. SCHAAP TNO, Unit Environment, Health and Safety, PO Box 80015, 3508 TA Utrecht, The Netherlands (*correspondence: [email protected]) Sea salt aerosol can reach high concentrations over the ocean. There, it has a significant effect on climate and weather due to its impact on the radiation budget and cloud formation. Over land, the concentrations rapidly decrease with increasing distance to the coast. Still, sea salt can make up a significant part of observed Particulate Matter (PM10) concentrations there. Due to adverse health effects of PM10, legislation has been imposed and recently the composition of aerosol has gained attention. As a consequence, sea salt measurements have become available. We will present the first compilation of measurements of sea salt concentrations over Europe. Measurements originate from several countries and campaigns. Both annual mean concentrations and time variability were investigated. We also present modelled sea salt concentrations (LOTOS-EUROS model) to complete the picture. They were compared with observations, revealing a good time correlation but an overestimation for the higher concentrations. It is well known that the sea salt source functions and deposition parameterizations are quite uncertain. Some sensitivity experiments were done to illustrate the consequences of these uncertainties. The observations can be used to constrain them.

Figure 1 Modelled annual mean sea salt concentrations in µg/m3, scaled with observations.

Formation and transformations of pyromorphite nanocrystals in the environment: Review M. MANECKI*, J. FLIS AND T. BAJDA AGH University of Science and Technology, Department of Mineralogy, Petrography and Geochemistry, Kraków, Poland (* [email protected]) Pyromorphite Pb5(PO4)3Cl is a stable, insoluble, crystalline phase which precipitates very easily when Pb2+, PO43-, and Cl- ions meet in the solutions within contaminated soils and wastes. It’s formation is the basis of in situ immobilization of Pb – a modern metod of reclamation. The nanocrystals with well ordered apatite structure are very hard to find and identify in the field samples. Most of our knowledge comes from laboratory experiments. Pyromorphite (PY) forms through homogeneous or heterogeneous precipitation from aqueous solutions. Heterogeneous nucleation is observed when a source of Pb2+ or PO43- ions (dissolving mineral containing Pb or P as well as desorbing surface of a mineral or bacteria in suspension) releases ions to the solution slower than the kinetics of precipitation. Various cationic substitutions for Pb are possible. Recently, anionic substitutions for PO4 were studied extensively which are especially critical for understanding of AsO4 mobilization. Similarly to precipitation, the kinetics of PY dissolution is very fast. Solubility of PY strongly depends on pH being lowest between 7 and 9. The results of most recent experiments indicate that the solubility constant of nanocrystals is higher than reported in the literature and equals to logKsp = -79.6. In contrast to some previous reports, dissolution is exothermic and the solubility increases with temperature. Equilibrium dissolution experiments at various temperatures allowed for more precise determination of thermodynamic constants: ∆H°f = -4108 ±60 kJ mol-1, ∆G°f = -3764 ±60 kJ mol-1, ∆S° = 622 ±542 J mol-1 K-1. Fluid cell AFM studies of surface features resulting from dissolution indicate surface controlled mechanism of dissolution with strong anisotropy with respect to crystallographic orientation. Solubility of PY increases significantly in the presence of complexing agents (e.g. EDTA, lactic acid, acetic acid) and products of bacterial metabolism (e.g. siderophores). This suggests the possibility of long term Pb-remobilization by PY dissolution induced by the activity of living organisms in the soil. Experiments with bacteria mediated dissolution of PY nanocrystals are in progress. This work was supported by research project N N307 101535.


Ligand effects on the oxidative stability of CdSe nanoparticles

Deep sea corals off Brazil verify a reduction of NADW formation during H2, H1 and the YD

A.N. MANGHAM1*, K.M. LOUIS, A.M. BRAMSON, K.M. METZ2, J.A. PEDERSEN1 AND R.J. HAMERS1

A. MANGINI1, J.M. GODOY2, M.L. GODOY2, R. KOWSMANN3, G.M. SANTOS4, M. RUCKELSHAUSEN1, A. SCHROEDER-RITZRAU1 5 AND L. WACKER

1

University of Wisconsin-Madison, Madsion, WI 53706, USA (*correspondence:[email protected]) ([email protected]) 2 Albion College, Albion, MI 59224, USA

Headgroup dependent stability of CdSe nanoparticles under evironmentally relevant oxidative conditions Alkyl-functionalized CdSe nanoparticles can be rendered stable in aqueous solutions by wrapping with amphiphilic copolymers[1,2]. However, the stability of the ensemble also depends on the choice of headgroup that binds to the nanoparticle. Here, we use an in vitro biomimetic assay to characterize how the choice of ligand headgroup impacts stability under controlled oxidizing conditions[3], using carboxylic acid, phosphonic acid, and thiol headgroups. Our results indicate significant differences in stability according to headgroup, as shown in the figure below. Figure 1: Headgroup dependent particle degradation.

Discussion of Results In agreement with prior studies, we find that wrapping nanoparticles with an amphiphilic polymer can enhance particle stability under oxidizing conditions. [2] However, the choice of headgroup on the initial alkyl ligands still has important consequences due to differences in packing density and thermodynamic stability of the surface bonds. Using infrared and x-ray spectroscopies, combined with thermogravimetric analysis allows us to relate differences in stability of polymer-wrapped nanoparticles to the chemical and physical structure of the ligands. [1] Colvin et al (2007) J. Am. Chem. Soc.129,2871-2879. [2] Smith et al (2006), PCCP 8, 3895-3903. [3] Metz et al. (2009) Env.Sci & Tech. ASAP

A827

1

Heidelberg Academy of Sciences, Heidelberg, Germany ([email protected]) 2 IRD, Rio de Janeiro, Brazil 3 Petrobras-CENPES, Rio de Janeiro, Brazil 4 Keck-CCAMS Facility, Irvine, USA 5 Laboratory of Ion Beam Physics, ETH Zurich, Switzerland Th/U ages of deep sea corals genus (Lophelia and Solenosmilia) sampled in sediment cores from two nearby locations off the coast of Brazil at water depths between 600 and 800 m group close to Henrich events H2, H1 and the Younger Dryas, suggesting that these periods were more favourable for coral growth than conditions during most of the Holocene and Late Glacial. The enhanced productivity of corals may be ascribed to higher amounts of nutrients in surface water transported by a more efficient upwelling of the nutrient richer deep water. The ∆14C of the Southern Source Water (SSW) bathing the corals in H2, H1 and the Younger Dryas is up to 400‰ lower than the corresponding atmospheric values. Ventilation ages, partly exceeding 4,000 years together with the higher Cd/Ca ratios are a strong indication for a larger admixture of the SSW due to the reduction of North Atlantic deep water formation during these periods, as earlier deduced from the ratio of 231Pa/230Th in deep sea sediments.

A828


Biochar application in Tamil Nadu and the global food crisis

Fluid-absent melting of pelites at subarc depths

UTRA MANKASINGH1, POON-CHUNG CHOI1 2 AND VALA RAGNARSDOTTIR

U. MANN AND M.W. SCHMIDT

1

Dept. of Earth Sciences, Univ. of Bristol, Bristol, BS8 1RJ, UK (*correspondence: [email protected]) 2 School of Engineering and Natural Sciences, Univ. of Iceland, Reykjavik, Iceland ([email protected]) The global food crisis is affecting Tamil Nadu, Southern India because of soil degradation and increased prices of fertilisers and pesticides. The plot-scale evaluation of biochar application to the agricultural soils is presented here to investigate its potential in improving soil fertility and crop yield. Biochar is an excellent soil amendment for sequestering carbon, for increasing organic carbon and water retention as well as providing habitat for microbes. Biochar also adds some macro- (P, K, N, Ca, Mg) and micronutrients (Cu, Zn, Fe, Mn) which are needed for sustainable agriculture. Twelve soil plots, 2 m x 1 m, each with different soil amendment, were prepared in July 2009. Combinations of biochar (from rice husks and Cassia sp. stems) and/or compost were applied and incorporated into the soil. Okra and cluster beans crops were rotated on selected plots between July 2008 and January 2009. Soil and plants from each plot were sampled during each harvest. Preliminary results indicate that the soils are porous with low moisture content (10 wt% via increase in polymerization as melting is approached from low T. Ca-bearing systems display similar effects [8]. Thus, polymeric aluminosilicates form a structural “backbone” of subduction-zone fluids, promoting critical mixing of H2O and melt, enhancing solubility of trace elements [9], and influencing mass transfer. [1] Newton & Manning (2008) Earth Planet. Sci. Lett. 274 241-249; [2] Newton & Manning (2002) Geochim. Cosmochim. Acta 66 4165-4176; [3] Newton & Manning (2003) Contrib. Mineral. Petrol. 146 135-143; [4] Newton & Manning (2000) Geochim. Cosmochim. Acta 64 2993-3005; [5] Manning (2007) Geofluids 7 258-269; [6] Tropper & Manning (2007) Chem. Geol. 240 54-60; [7] Newton & Manning (2008) Chem. Geol. 249 250-261; [8] Newton & Manning (2007) Geochim. Cosmochim. Acta 71 5191-5202; [9] Manning et al. (2008) Earth Planet. Sci. Lett. 272 730-737.

PVTx properties of chloride-rich aqueous fluids at high P-T conditions DAVIDE MANTEGAZZI1*, CARMEN SANCHEZ-VALLE1 2 AND THOMAS DRIESNER 1

Inst. for Mineralogy and Petrology, ETH Zurich, CH-8092 Zurich (*correspondence: [email protected], [email protected]) 2 Inst. of Isotope Geochemistry and Mineral Resources, ETH Zurich, CH-8092 Zurich ([email protected]) Binary mixtures H2O-NaCl are considered as good approximations of natural geological fluid in a wide range of processes in the Earth’s crust and mantle. Typical examples of such geological events are: metamorphic reactions, hydrothermal alteration of the seafloor, formation of ore deposits and magma production. Despite the key role of these fluids only few experimental data on the themodynamical properties of fluids other than pure H2O [1-3] are available at high pressure and temperature conditions. For instance, the equations of state (EoS) for H2O-NaCl mixtures are restricted to 0.5 GPa [4]. The knowledge of the thermodynamic properties of these fluids at geologically relevant P and T conditions is essential for the understanding and the quantitative modelling of fluid-mediated geological processes. Therefore more experimental data at high P-T conditions are needed. In this contribution, we present PVTx properties of chlorinated aqueous fluids (namely H2O-NaCl mixtures) with variable salinities determined from acoustic velocity measurements at high P-T conditions. Measurements were performed using Brillouin scattering spectroscopy in combination with externally heated diamond anvil cells (DAC). The EoS obtained from this work are further used to evaluate the P-T dependence of thermodynamic properties of chlorinated binary fluids, including thermal expansion coefficients, isothermal and adiabatic compressibilities and heat capacities. The results are combined with previous experimental and theoretical EoS of H2O-NaCl mixtures [4] to provide an internally consistent dataset for the thermodynamical properties of the most relevant aqueous systems involved in fluid-mediated processes in the Earth’s crust and mantle. [1] Wagner and Pruss (2002) J. Phys. Chem. Ref. Data, 31, 387–535. [2] Abramson and Brown (2004) GCA, 68, 18271835. [3] Sanchez-Valle and Bass (2007) GCA, 71, A873A873. [4] Driesner (2007) GCA, 71, 4902-4919.


Anomalous Na contents in EET90299 chondrules mesostasis

Characterization of competitive binding of Eu(III)/Cu(II) and Eu(III)/Ca(II) to Gorleben humic acid

P. MANZARI AND N. MELONE* Dipartimento Geomineralogico, Università di Bari, Italy (*correspondence: [email protected]) Genetic relationship among E-chondrites are still poorly understood. So, firstly, we began to investigate the geochemical relationship between mesostasis and crystalline phases in chondrules of different E-chondrite types. EET90299 is an unequilibrated enstatite chondrite (EL3) [1]. A thin section of EET90299 showed the occurrence of several chondrules in a range of 400 to 2000 µm in size. Five chondrules were selected from this section, on the base of microstructural features [2]. As it can be seen in fig.1, EET90299 chondrules showed a strong albitic-normative mesostasis. Those results were plotted with other analyses on chondrule mesostasis that occurred in EL3 chondrites, (ALH85119, PCA91020, MAC88180) Schneider et al (2002) [3]. 10

ETC1 ETC2 ETC3

8

ETC6

wt%Na 2O

ETC5 ALH chd 37 MAC chd 3, 12 PCA chd 4,19,23,41,42,U1

6

4

2

0 0

2

4 wt%CaO 6

8

10

12

Figure 1. Na2O vs. CaO in EL3 chondrule mesostasis: this work (open symbol) and Schneider et al., 2002 (closed symbol). We find Na-plagioclase composition for all the chondrule mesostasis except for one that shows a more anorthitic composition. These features stand between EH3 and EL3 type chondrule mesostasis, following Schneider et alii scenario. It could means that the difference in chemical compositions could reflect local variations in the nebular environment, or that EET90299 underwent a more rapid cooling. However, other investigations are in progress on other chondrules from this thin section to compare them with EH3 chondrules. [1] Grossman J.N.(1994), Meteoritics, 29, 1, 100-143; [2] Manzari et al. (2008), 33rd Geological Congress,Oslo; [3] Schneider et al. (2002), M&PS, 37, 1401-1416.

A831

LAURA MARANG1,2, SASCHA EIDNER3, MICHAEL KUMKE3, MARC F. BENEDETTI2 1 AND PASCAL E. REILLER 1

CEA, CE Saclay, DEN/DANS/DPC/SECR/Laboratoire de Speciation des Radionuclédies et des Molécules, Bat. 391 PC 33, F-91191 Gif-sur-Yvette CEDEX, France 2 Laboratoire de Géochimie des Eaux, Université Paris Diderot, IPGP and UMR CNRS 71574, Case Postale 7052, F-75251 Paris Cedex 05, France 3 Institute of Chemistry, University of Potsdam, KarlLiebknecht-Straße 24-25, D-14476 Potsdam-Golm, Germany In an area that contains high concentrations of natural organic matter, it is expected to play an important role on the speciation of trivalent radionuclides. Competitive interactions with H+ and major cations, e.g. Ca2+ or Mg2+, could influence these metals transport and bioavailability. Competitive experiments between Eu3+ and cations which can bind differently to humic substances, would bring an improved understanding of the competitive mechanisms. The aim of this study is to acquire data for Eu(III)/Cu(II) and Eu(III)/Ca(II) competitive binding to a sedimentary-originated humic acid (Gorleben, Germany). The NICA-Donnan parameters [1] for Ca(II), Cu(II), and Eu(III) obtained from competitive binding experiments using Ca2+ or Cu2+ ion selective electrodes (ISE), were used to model time-resolved luminescence spectroscopy (TRLS) measurements. Then the TRL spectra and decay times were interpreted to check the consistency of the modelling. From ISE data, Eu(III) and Cu(II) are in direct competition for the same type of sites, whereas Ca(II) has an indirect influence through electrostatic binding. The spectroscopic interpretation of the competition experiments showed two strikingly different environments for the Eu(III)/Cu(II) and Eu(III)/Ca(II) systems. Cu(II) seems to expel more effectively Eu(III) into an aquous like environment within the humic acid structure, i.e., the Donnan phase, and to the aqueous phase as free Eu3+. This is evidenced both from the spectra as well as from the decrease in the luminescence decay times. Moreover, Ca(II) causes a slighter modification of the chemical environment of the humic-complexed Eu(III). [1] Kinniburgh et al. (1999) Colloids Surf. A 151, 147-166.

A832


Persistence of mantle lithospheric Re-Os signature during lithosphere-asthenosphere interaction: Insights from in situ isotopic analysis of sulfides from the Ronda peridotite (S. Spain) CLAUDIO MARCHESI1*, WILLIAM L. GRIFFIN2, CARLOS J. GARRIDO3, JEAN-LOUIS BODINIER1, SUZANNE Y. O’REILLY2 AND NORMAN J. PEARSON2 1

Géosciences Montpellier, Montpellier, France (*correspondence: [email protected]) ([email protected]) 2 GEMOC ARC National Key Centre, Sydney, Australia ([email protected], [email protected], [email protected]) 3 Instituto Andaluz de Ciencias de la Tierra, Granada, Spain ([email protected]) The Ronda peridotite massif (S. Spain) mainly consists of highly foliated spinel-peridotite tectonites and undeformed granular peridotites that are separated by a recrystallization front. The spinel tectonites are interpreted as vestiges of ancient subcontinental lithospheric mantle and the granular peridotites as a portion of lithospheric mantle that underwent partial melting and pervasive percolation of basaltic melts induced by Cenozoic asthenospheric upwelling. The Re-Os isotopic signature of sulfides from the granular domain and the recrystallization front mostly coincides with that of grains in the spinel tectonites. This indicates that the Re-Os radiometric system was highly resistant to partial melting and melt percolation induced by Cenozoic lithospheric thermal erosion. The Re-Os isotopic systematics of sulfides in the Ronda peridotites thus mostly conserves the memory of ancient magmatic events in the lithospheric mantle. Os model ages record two melting episodes at ~ 1.6-1.8 Ga and 1.2-1.4 Ga, respectively. A new generation of sulfides precipitated in peridotites at ~ 0.7-0.9 Ga. These different Proterozoic Os model ages are consistent with similar results obtained for several mantle suites in central/western Europe and northern Africa as well as with Nd model ages inferred for the continental crust of these regions. This suggests that the events recorded in mantle sulfides of the Ronda peridotites reflect different stages of generation of the continental crust in the ancient Gondwana supercontinent.

Organic aerosols: Liquids or glasses? C. MARCOLLI1*, B. ZOBRIST1,2, U.K. KRIEGER1, B.P. LUO1, V. SOONSIN1, T. PETER1, D.A. PEDERNERA2 AND T. KOOP2 1

ETH Zurich, Institute for Atmospheric and Climate Science, Zurich, Switzerland (*correspondence: claudia.marcolli @env.ethz.ch) 2 Department of Chemistry, Bielefeld University, Germany Depending on their concentration and composition, aerosols affect various atmospheric properties and processes, such as atmospheric chemistry and Earth’s radiative budget. There are several factors which determine the physical state of an aerosol: chemical composition and mixing state of its constituents, temperature and ambient relative humidity (RH). The atmospheric aerosol itself is a complex mixture of various inorganic and organic components, whereas the organic fraction can represent more than 50% of the total aerosol mass. The organic aerosol fraction is expected to be present in a liquid or glassy state even at low relative humidity (RH), because the very large number of organic compounds depresses the temperature at which crystalline solids form [1, 2]. Whether aerosol particles are present as liquids or as glasses may influence their properties, e.g. water uptake, aerosol chemistry, as well as ice nucleation and ice crystal growth. We investigated the glass transition temperatures (Tg) of a series of aqueous organic solutions such as polyols, sugars and dicarboxylic acids as a function of the solute concentration using a differential scanning calorimeter (DSC) [2]. These measurements show that the higher the molar mass of the organic solutes, the higher Tg of their respective solutions at a given water activity. Aerosol particles containing larger (≥150 g mol−1) organic molecules are therefore likely to form glasses in the upper troposphere. Moreover, we performed hygroscopicity cycles of single levitated sucrose particles at different temperatures using an electrodynamic balance (EDB). The hygroscopicity cycles performed at 291 K for example showed for crystalline sucrose water uptake at roughly 85% RH due to deliquescence whereas glassy particles started to take up water already at ~40-45% RH and turned fully liquid above 55%. The corresponding Tg inferred from DSC experiments is expected at 30% RH. This shows that a glass-to-liquid transition occurs by increasing RH, but that water uptake is delayed above the Tg obtained in DSC experiments. We therefore conclude that water uptake by organic aerosol particles at temperatures important for cirrus clouds formation is significantly impeded. [1] Marcolli et al. (2004) J. Phys. Chem. 108, 2216-2224. [2] Zobrist et al. (2008) Atmos. Chem. Phys. 8, 5221-5244.


A833

Trace element partitioning and redox states in a ferromanganese nodule from the SW Pacific

Micro-scale study of δ18O and δ30Si in Precambrian cherts: Implications for oceanic temperatures reconstructions

M.A. MARCUS1*, S.C. FAKRA1, B.M. TONER2, G. HORN3 AND K.J. EDWARDS3

J. MARIN1*, M. CHAUSSIDON1 AND F. ROBERT2

1

Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley CA USA 94720 (*correspondence: [email protected]) 2 Department of Soil, Water, and Climate, University of Minnesota – Twin Cities, St. Paul, MN USA 55108 ([email protected]) 3 Department of Biological Sciences University of Southern California, Los Angeles, CA, USA ([email protected], [email protected]) Marine ferromanganese nodules have attracted much interest for economic reasons due to their Ni and Co content. Nodules are composed of chemically-active materials (nanostructured oxides) which effectively sorb trace metals delivered to the seafloor by sorption onto biogenic particles which then settle to the bottom and undergo reactions which grow the nodules. This process results in growth rates measured in mm/Mya, making nodules some of the slowestgrowing materials known. Yet, they are made of nanophase material which has resisted coarsening for tens of Mya. We present µ-XRF, µ-XRD, and µ-XAS measurements for a nodule from a deep ocean site underlying biologically unproductive waters. The Fe oxides in this nodule mostly consist of goethite and ferrihydrite in an Fe-rich matrix plus disordered phases in Mn-rich regions. These disordered phases display long Fe-Fe distances indicative of possible phosphate incorporation in the oxides. The near-surface ("Outer") and interior ("Inner") exhibit differing; the Inner region is richer in Mn, Co and oxidized forms of Co, Ti and V than the Outer. In the Outer region, Co, Ce, and V are reduced to their lowvalent forms, while in the Inner, these elements are partially oxidized. Correlations of µ−XANES spectra and XRF maps suggest that Ce and V are sorbed to Fe oxides as Ce(III) and V(IV), and Mn oxides, as Ce(IV) and V(V). Principal component analysis of the µ−XRF map suggests that in each region there are three patterns of distribution such that the distribution of each element may be represented as a linear combination of these basis images. These results suggest that common processes control the deposition of major and trace elements.

1

CRPG-CNRS, Nancy Université, 15 rue Notre Dame des Pauvres 54501 Vandoeuvre-lès-Nancy, France (*correspondence : [email protected], [email protected]) 2 Laboratoire de Minéralogie et Cosmochimie du Muséum UMR-CNRS 7202 Case 52 - 57 Rue Cuvier 75231 Paris Cedex 05([email protected]) Variations of the oxygen and silicon isotopic compositions of archean cherts can be used to reconstruct oceanic paleotemperatures (Knauth and Lowe, 1978 [1], Robert and Chaussidon, 2006 [2]). For O however it is assumed that seawater δ18O remained constant around 0‰ (Holmden ann Muelhenbachs, 1993 [3]). However, these isotopic records can be reset during burial diagenesis or through isotopic exchange with hydrothermal fluids. At a given age, cherts show a range of isotopic compositions, which makes paleo-temperatures reconstructions more difficult. In order to better understand these variations, we performed a microscale study of δ18O and δ30Si in five precambrian cherts of the Gunflint Iron formation (1.9 Ga, Canada) by ion microprobe (Cameca 1270, CRPGCNRS, Nancy). Around 100 analytical spots were made in each sample to detail the variation of isotopic composition in the different forms of silica (microquartz, megaquartz, fibrous quartz, detrital quartz and quartz vein). The Gunflint cherts show a typical 4.5 - 6.6 ‰ range for δ18O in microquartz and different δ18O values for the different forms of silica. Microquartz has preserved at a µm-scale a strong heterogeneity inherited from its diagenetic history. Theses cherts show δ30Si between -2.07‰ to +3.06‰, a larger range than found previously (Robert and Chaussidon, 2006). The δ30Si variations, contrary to δ18O, cannot be explained by a model based on dissolution-precipitation of an opal precursor. The formation of Gunflint cherts must involve fluids with different δ30Si, i.e. different sources of silicon (seawater, hydrothermal, ...). This approach may bring new evidences on the origin of the Gunflint cherts and may permit to better constrain oceanic paleo-temperatures. [1] Knauth L.P., Lowe R.D., (1978). Earth and Planetary Science Letters 41, 209-222.[2] Robert F., Chaussidon M., (2006). Nature 443 969-971. [3] Holmden C. Muehlenbachs K., (1993) Science 259, 1733-1736


A834

Usage of tritium, δD, δ18O and chemical data in the hydrogeological investigations of the karstic area – Lička Jasenica

Development of a transmitted-light dual-window UHV laser cell for in situ 40Ar-39Ar geochronology DARREN FRANCIS MARK NERC Argon Isotope Facility, Scottish Universities Environmental Research Centre, Rankine Avenue, Eask Kilbride, G75-0QF, Scotland, UK ([email protected]) In situ high spatial resolution ultraviolet (UV) laserprobe ablation permits Ar extraction from specific target areas identified within discrete mineral phases and 40Ar-39Ar dating of intracrystal zonation and phase trnasitions (e.g. Mark et al., 2005). A laser spot resolution of 8 µm can now be achieved by the latests UV laserprobes but the optic systems for normal UHV laser cells rely on reflected light technology. Reflected light produces low-resoltuion images with respect to discrimination of mineral phases, grain boundaries and zonation etc. Because of the poor optics, poorly-polished thick slices of rocks and minerals are the normal samples used for in situ 40Ar-39Ar geochronology. This contribution describes the development and application of a transmitted-light dual-window UHV laser cell for in situ 40Ar-39Ar geochronology. The cell has been designed and constructed in house at the NERC Argon Isotope Facility, SUERC and offers the users the ability to view samples in transmitted plane-polarised light (Fig. 1), transmitted cross-polarised light and reflected light (ring and coaxial sources). Doubly-polished thin wafers (~80 µm) of rock and minerals are utilised as are individual crystals and grains (e.g. K-feldspar and muscovite).

T. MARKOVIĆ1*, J. TERZIĆ2 AND I. KRAJCAR-BRONIĆ3 1

Croatian Geological Survey, Sachsova 2, Zagreb, Croatia (*correspondence: [email protected]) 2 Croatian Geological Survey, Sachsova 2, Zagreb, Croatia 3 Rudjer Boskovic Institute, P.O. BOX 180, Zagreb, Croatia Traditional investigations of groundwater resources in karstic areas usually utilize geological, hydrogeological and water quality data in order to establish a conceptual model for the investigated aquifer. Sometimes, such data are not always fully available. In order to overcome these obstacles the combined hydrogeological and geochemical approach was used for a conceptual model of the investigated karstic aquifer. In August and November 2007 and April 2008, water samples were collected from two springs: Veliko vrelo and Malo vrelo. Prior to taking groundwater samples, EC, TDS, T and pH were measured. Water samples were analyzed by LabAlliance ion chromatographer (concentrations of major anions) and Perkin Elmer AAS (concentrations of major cations) at the Croatian Geological Survey. The δ18O and δD were analyzed by using the CO2 equilibration [1] and the zinc reduction method [2] at the Joanneum Institute, Graz. Tritium activity in water samples was measured at the Ruđer Bošković Institute by a gas proportional counting (GPC) technique. From water sample (50 ml), CH4 is obtained by reaction of water with aluminium carbide at 150°C [3]. Purified CH4 is then used as a counting gas in a multi-wire GPC [4]. The lowest tritium activity that can be distinguished from the background, i.e., the limit of detection is 1.9 TU. According to the chemical composition the spring waters belong to the Ca-HCO3 hydrochemical type. Total dissolved solids, EC, T and δ18O and δD show that on both springs have the same catchments area. The lowest value of 3H was measured on Veliko vrelo in 08-2007 (200) generally indicative of slab derived melts can be produced by 40g/t Au) vein within the bonanza zone and low-grade (