DEFROST (DEep Flow Regime Off SpiTsbergen)

PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER)

DEFROST (DEep Flow Regime Off SpiTsbergen) Cruise Report Authors: Manuel Bensi1 ([email protected]), Vedrana Kovacevic1, Leonardo Langone2, Cinzia De Vittor1, Federica Relitti1, M. Bazzaro1, D. Deponte1, R. Laterza1, Renata G. Lucchi1, Michele Rebesco1 (not on board), Laura Ursella1 (not on board), Stefano Aliani2 (not on board), Stefano Miserocchi2 (not on board), and with the collaboration of the EUROFLEETS-2 BURSTER Team 1. 1 2

OGS, Trieste, Italy. CNR-ISMAR, Bologna, Italy

Date: 17/02/2017 1

OGS Report n° 2017/10 Sez. OCE 5 EXO

Lucchi et al., 2016. (OGS BURSTER Cruise Report)

1

Bensi M. et al. (2017)

PS99.1 DEFROST cruise report, 2017/16 Sez. OCE 5 EXO

PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) 1

INTRODUCTION: PNRA-DEFROST ACTIVITIES DURING PS99.1 CRUISE (BREMERHAVEN-LONGYEARBYEN, 13-23 JUNE 2016)

The southwestern region off Svalbard (Fig. 1.1) is an area where water masses with different properties interact with each other: Atlantic waters (AWs), considerably warmer than the locally formed dense waters, flow northwards (West Spitsbergen Current, WSC) along the eastern side of the Fram Strait, keeping this region nearly ice-free even during winter season, while cold Arctic waters (East Greenland Current, EGC) flow southward in the western part of the strait contributing to the maintenance of the Greenland ice cap. Additionally, dense waters are formed during winter through freezing and brine release in the polynyas of the Barents Sea, particularly in the Storfjorden. These ocean processes have strong implications on the Atlantic Meridional Overturning Circulation (AMOC) and on the climate. Shelf dense water plumes are also responsible for the accumulation of contourites (sedimentary structures affected by along slope bottom currents), whose onset coincides with the Early Pleistocene glacial expansion. The study of these contourites can provide valuable information on the history of ocean circulation and past climate variability. In particular, two contourites were recently discovered in the area: the Isfjorden and Bellsund contourite drifts (Rebesco et al., 2013). The research project DEFROST (DEep Flow Regime Off SpiTsbergen), funded through the Italian Arctic and Antarctic National Program (Programma Nazionale di Ricerche in Antartide-PNRA) aims to investigate the temporal and spatial variability of the deep flow in the area of the above mentioned contourites, with emphasis on the near-bottom currents and their associated physical and biogeochemical properties. In-situ measurements are conducted mainly by means of deep moorings, deployed in the layer between 1000 and 1500 m water depth. They are equipped with current meters (ADCP, RCMs), temperature, salinity, dissolved oxygen sensors (SBE37, SBE16), and sediment traps (McLane). The choice of using moorings is motivated by the fact that the most energetic processes, which are able to reshape the seabed and form contourites, occur in late winter and early spring, when surveys done by means of research vessels are hardly feasible due to the harsh environmental conditions in the area. Moreover, winds and ocean cooling change according to mild or strong winters, and so affect the volume and density of the dense water plumes, and hence of the cascading flow. Therefore, long lasting measurements, extended to more than one year by means of the moored sensors are needed to assess the year-to year variability. A multidisciplinary team composed by oceanographers and geologists will study current characteristics, thermohaline properties, sedimentary processes, and seismic data in order to assess the link among the present seabed shape, deep-water flow and dense water plumes cascading. This scientific activity follows up previous international initiatives: the EUROFLEETS2-PREPARED (Present and PAst flow REgime on contourite Drifts west of Spitsbergen) cruise carried out in June 2014 (RV G.O. Sars), and two following cruises carried out in the same region in June and September 2015, respectively with the RV Helmer Hansen (HH cruise, Uni Tromsø, Norway) and RV OGS-Explora (EXPLORA cruise, OGS, Italy). This report describes the activities conducted during the oceanographic cruise PS99.1 (BremerhavenLongyearbyen) and referred to the DEFROST project activities. It includes photos taken on board during the daily activities. The cruise was carried out on board the RV POLARSTERN

2



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) (http://www.awi.de/en/infrastructure/ships/polarstern/), a 118m Ice Going Multipurpose Research Vessel (AWI - Alfred Wegener Institute for Polar and Marine Research). The teacher at sea, participating to the cruise through the GIFT – Geosciences Information For Teachers programme (C. Le Gall) was in charge to write, together with the AWI coordination staff, daily reports for the BURSTER-EuroFLEETS2 activities carried out during the same oceanographic cruise. Hence, more information about the cruise is available at the following links: 1. http://eurofleets2BURSTER.blogspot.it/ 2. https://www.facebook.com/eurofleets2BURSTER2016/ 3. https://www.awi.de/nc/en/expedition/ships/polarstern/weekly-reports/single-view/presse/dieexpedition-ps-99-bremerhaven-nach-tromsoe-uebersicht.html 4. https://www.awi.de/nc/en/expedition/ships/polarstern/weekly-reports/single-view/presse/esgeht-los-endlich.html

Fig. 1.1. Study area (dashed square in panel A). A) Bathymetry of the region with a schematic representation of the general ocean circulation. B) Location of the study area within the Arctic Ocean (adapted and modified from Jakobsson et al., 2012).

3




PEOPLE ON BOARD (SCIENTIFIC CREW)

No. NAME / FIRST NAME / INSTITUTE / PROFESSION [Alphabetic order] (this list also includes people from AWI which are not in the photos in Fig. 2.1)

1

Bauerfeind Eduard, AWI, Biologist

28

Musco Elena, OGS, Student apprentice

2

Bazzaro Matteo, OGS, Biochemist

29

NN DWD, Meteorologist

3

Bensi Manuel, OGS, Oceanographer (DEFROST Group Leader); email: [email protected] Biebow Nicole, AWI, Yeoman Carbonara Katia, Uni Parma, Student apprentice Caridi Francesca, Uni Marche, Biologist

30

30 NN DWD, Technician,Meteorology

31 32 33

Daniel Claudia, AWI, Technician, biology De Vittor Cinzia, OGS, Biochemist Deponte Davide, OGS, Eng. Technician, oceanography Dominiczak Aleksander, Uni Poznań, Student apprentice Gamboa Sojo Viviana María, Uni Pisa, Micropaleontologist Graziani Stefano, Uni Rome, Technician, oceanography Gutow Lars, AWI, Biologist Hellmann Sebastian, AWI, PhD student

34 35 36 37

Povea Patrizia, Uni Barcelona, Geochemist Relitti Federica, OGS, Biochemist Richter Klaus-Uwe, AWI, Engineer, biogeochemistry Rogge Andreas, AWI, PhD student Rokitta Sebastian, AWI, Biogeochemist Ruggero Livio Uni Rome, Technician, Oceanography Rui Leonardo OGS, Student apprentice

38

Sabbatini Anna, Uni Marche, Micropaleontologist

39

Sablotny Burkhard, AWI Engineer, biology

40 41

43 44 45 46 47 48 49 50 51

Salter Ian, AWI, Biologist Sánchez Guillamón Olga, IEO Malaga, Student apprentice Soltwedel Thomas, AWI, Biologist (PS99 Chief Scientist); email: [email protected] Stronzek David, AWI, PhD student Tagliaferro Massimo, HITACHI, Technician Tippenhauer Sandra, AWI, Oceanographer Topchiy Maria, Uni Oslo, Geochemist Wiberg Daniel, Uni Tromsø, Geophysician Wulff Thorben, AWI Engineer, biology Zoch Daniela, BGR, Geomicrobiologist PHINS SAT NN PHINS SAT

52 53

NN PHINS SAT NN PHINS SAT

4 5 6 7 8 9 10 11 12 13 14

15 Knüppel Nadine, AWI Technician, biology 16 17 18 19 20 21 22 23 24 25 26 27

42

Kondak Konstantin, DLR Engineer, robotics Kovacevic Vedrana, OGS Oceanographer Krauß Florian, AWI, Student apprentice Krüger Martin, BGR, Geomicrobiologist Langone Leonardo, ISMAR, Oceanographer Laterza Roberto, OGS, Technician Le Gall Christophe, GIFT, High school teacher Liu Yangyang, AWI, PhD student Lucchi Renata Giulia, OGS, Sedimentologist (BURSTER Group Leader); email: [email protected] Maier Moritz, DLR, Engineer, robotics Mazzini Adriano, Uni Oslo, Geochemist Morigi Caterina, Uni Pisa, Micropaleontologist

4




Fig. 2.1. Scientific members of the BURSTER and DEFROST teams.

5




RV POLARSTERN INFO

Port of registry Length Width Max. Draught Max. Displacement Empty weight Commissioning Engine Engine power Range Max. Speed Operation area Crew Shipyard Scientists

Bremerhaven 118 metres 25 metres 11.20 metres 17,277 tons 12,012 tons AWI 1982 4 x KHD RBV 8M540 19,198 PS (four engines) 19,000 nautical miles / 80 days 16 knots Everywhere including pack ice zone 44 Nobiskrug, Rendsburg and Howaldswerke - Deutsche Werft Kiel AG, Germany 53

Fig. 3.1. RV Polarstern in front of Longyearbyen (photo by M.Bensi).

6




SCIENTIFIC EQUIPMENT USED ONBOARD ● SeaBird 911plus CTD (Conductivity-Temperature-Depth) mounted on the SBE 32 Carousel Water Sampler equipped with 24 Niskin Bottles (12 l capacity): used to collect multiparametric (Temperature, Conductivity/salinity, Dissolved Oxygen, Fluorescence, Light Transmission) vertical profiles from the surface down to the bottom. Niskin bottles are used to collect water samples at desired depths. The CTD configuration and a water sampler are shown in Fig. 4.1:

Fig. 4.1. Sensor list (on the left hand side) of the SBE CTD+Rosette system (on the right hand side). ● RDI ADCP (Acoustic Doppler Current Profiler) Vessel mounted, 150 kHz: used to collect info about ocean currents (speed and direction) in the upper layer (20-300m below the surface). ● Shipboard Thermosalinograph: used to collect information about the sea surface, typically in flow-through systems operating continuously throughout a cruise. ● Oceanographic Mooring maintenance equipment. ● Water sample collection from Niskin bottles: used to perform chemical analyses in laboratory (partially on board and partially on land: Salinity, Dissolved Oxygen, Nutrient, Alkalinity, pH, Dissolved Inorganic Carbon)

7



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) All the oceanographic equipment and accessories were sent at the end of May 2016 from Trieste to Bremerhaven, to be embarked on the RV POLARSTERN before the beginning of the Arctic cruise.

Fig. 4.2. OGS container leaving OGS headquarter in May 2016 (photo by M.Bensi). 5

BRIDGE TIMETABLE OF EVENTS

Date time (UTC) June 12, 2016, Sunday

Activity Arrival of personnel at the Port of Bremerhaven, between 14:00 and 19:00

June 13, 2016, Monday

Boarding of the Scientific crew completed by 11:00. Safety meeting at 15:00 Departure from Bremerhaven at 17.00. Sailing towards Kveithola and Svalbard areas.

June 14, 2016, Tuesday

Opening of the container and setting up of the laboratories and some instruments

June 15, 2016, Wednesday

Activities plan definition, organization on board and data analyses of previous datasets. Presentation of BURSTER project.

June 16, 2016, Thursday

Seminar, presentation of DEFROST project. CTD team meeting in the mooring and of all the BURSTER groups’ activities in the afternoon

June 17, 2016, Friday

Seminar, Instruments settings, first CTD and carousel test in water down to 100m

June 18, 2016, Saturday

Seminar, Setting instruments, Seismic instruments testing, Transit on a volcano mud and sailing to Bear Island

June 19, 2016, Sunday

BURSTER; Kveithola area: CTD-water sampling, Multicorer (MUC), OFOS

June 20, 2016, Monday

BURSTER; Kveithola area: CTD-water sampling, OFOS

8




June 21, 2016, Tuesday

DEFROST; SW off shore Svalbard, S1 mooring recovery, CTD casts

June 22, 2016, Wednesday

DEFROST; S1 Mooring deployment, I2 mooring recovery, CTD casts. Data collection and storage. Packaging of the samples and instruments in the container. Finalization of the custom documents.

June 23, 2016, Thursday 09:00

Disembark of scientific crew at Longyearbyen

9



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) June 12, 2016, Sunday 16-18

Arrival of the OGS personnel at the Bremerhaven harbor; Boarding on the R/V POLARSTERN, accommodation in the cabin.

June 13, 2016, Monday By 11:00:

Arrival of all the crew and accommodation of all the scientific crew into the cabin.

15:00

Safety meeting with the 1st Officer

17:30

Leaving the port of Bremerhaven in direction of the Kveithola Trough

June 14, 2016, Tuesday 07:00

Meeting with the Captain, part of the Ship’s crew, and Chief Scientist in the lecture room. Presentation of the activities to be done during the PS99.1 cruise.

08:00

Opening of the container and setting up of laboratories and instruments.

June 15, 2016, Wednesday (rough sea, 3m wave, 35-40 knots wind, Fig. 5.1) 07:00

Daily seminars in the lecture room, presentation of the BURSTER activities and Meteorological situation. Preparation of the DEFROST presentation for the day after and review of the activity plan according to the ship-time available. Set up of the instruments

Fig. 5.1. During the navigation toward the study area (photo by M.Bensi).

10



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) June 16, 2016, Thursday 07:00

Daily seminars in the lecture room, presentation of the DEFROST activities, Meteorological situation, and Uni-Roma group’s activities.

08:15

Group photo on the Heli-deck.

08:30

CTD team meeting: OGS , ISMAR and AWI (Sandra Tippenhauer, AWI) to see how the CTD/Rosette system is operated.

12:00

Meeting with all BURSTER team for updated plans and for deciding how to proceed with multicores, box core, and OFOS activities.

Afternoon: Preparation of the freight lists and packing lists for shipping in LYB (2 Items), Tromsø (1 Item, SEM) and Bremerhaven (Refrigerates goods, Container). June 17, 2016, Friday 07:00

Daily seminars in the lecture room, Meteorological report (Fig. 5.2)

Fig. 5.2. Meteorological conditions regarding cloudiness during the navigation toward the study area. 08:30

CTD test in the water 120m depth, bottles closed, salinity sample collected, NMEA seems not connected to the PC system, Sandra Tippenhauer and Werner Dimmer (on-board technician from AWI) check it.

11:00

Meeting for mooring deployment on deck with the 1st Officer and mooring Team. The recovery on the side (starboard) of the ship envisaged. The crew also foresees the two possibilities for deployment: on the starboard of the ship or on stern the ship. The DEFROST team however raises some doubts related to the risks of a lateral deployment, due to the very high load that the mooring line can suffer. On the other side, the 1st Officer 11



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) says that they usually do in that way, especially for short moorings, and that in their opinion the load on the mooring line is lower during lateral deployment than during stern deployment. The final decision is up to the mooring Team. In dry laboratory: Set up RCM SEAGUARD (time GPS and configuration). Start recording today at 14:00, in order to check if it works properly. Battery 9.2 volt. Start recording 17-06-2016 at 14:00 UTC. Sampling time 60min. Test Deck unit releaser and IXSEA sn301: ok. June 18, 2016, Saturday 07:00

Daily seminars in the lecture room (METEO forecast, Seismic activities, AXED project)

11: 00

Mooring Team meeting. The RCM Seaguard is prepared and closed, ready for deployment. After discussion, we decide to try with a lateral deployment, as suggested by the crew.

12:00

CTD Team meeting with Sandra Tippenhauer to define some common procedures during CTD casts according with the German protocols on board (safety, sequence of operations, rules on board, etc…).

June 19, 2016, Sunday (0.5m wave, 6-10m/s wind, cloudy, light rain at the horizon) 05:00

Arrival of the ship in the BURSTER working area (Kveithola trough-mouth): CTD rosette at station C01, water sampling, 2 MUC (Multi corer) casts and OFOS (Ocean floor observation system) follow all day.

Fig. 5.3. Deployment of the CTD and Rosette (photo by C. Le Gall). 12



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) CTD and Rosette deployment (Fig. 5.3) is the first operation on the site. Data from the sensors seem quite noisy. Connectors cleaned. The comparison of the first dissolved oxygen profile from CTD upcast with Winkler data apparently seems acceptable (with expected offset), as shown in Fig. 5.4. 09:00

End station, proceeding to station 2 (C09).

09:00

Preparation for DEFROST activities (Fig. 5.5): Sediment trap and SBE37-ODO for mooring S1 switched on (StartLater command sent).

Fig. 5.4. Cloud chart (on the left hand side) used to monitoring the weather evolution and the comparison between dissolved oxygen data from CTD and Winkler analyses (on the right hand side).

13



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) Fig. 5.5. Preparation of the sediment trap and SBE37-ODO for mooring S1 deployment (photo by M.Bensi).

June 20, 2016, Monday (0.5-1.0m wave, 6-10m/s wind, cloudy) 00:00 – 24:00 CTD at Kveithola Through continues, water sampling. 12:00

CTD winch is changed due to problems with the 1° sea cable winding.

13:00

One possible flare of gases appeared from the parasound echo sounder data. The BURSTERN Team decides to perform an OFOS survey in the area, CTD with water sampling, and a Multicorer cast.

June 21, 2016, Tuesday (0.5m wave, 6 m/s wind, cloudy, light rain)

Fig 5.6. Ship’s track up to 20 Jun 2016. 14:50

DEFROST; the ship arrives at S1 mooring site.

15:13

Interrogation of the releaser --- ok, answer received, distance from the releaser 1079m, depth echo sound ship 1064m.

15:17

Release command sent --- ok, released. The ship moves back from the point. 14



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) 15:26

The Mooring surfaces in front of the ship. The recovery starts approaching the buoy at the starboard side of the ship (Fig. 5.7).

Fig. 5.7. Operations during mooring recovery and data downloading (photo by C. Le Gall).

16:04

Entire mooring line on board. The operations were conducted perfectly.

17:50

Beacon transmitted after leaving it on the helideck. Hence, we decided to avoid the update of the Firmware. We replaced old batteries with new ones and we switched on the beacon again, leaving it outside on the helideck. After mooring recovery, CTD casts at S1 and in the nearby area were performed. Water sampling executed only at station S1. Mooring maintenance ended approximately at 21:30. ADCP data download planned for the day after, because its re-deployment was not foreseen.

00:45

End of CTD casts in the S1 region (stations S1, DEF6, DEF7, DEF8, DEF9, DEF9_1)

June 22, 2016, Wednesday (0.5m wave, 3-4 m/s wind, partly cloudy) S1 mooring deployment operations: 15




Crew and mooring team on deck. We decided to operate on the starboard side because the crew uses to do so for short moorings. The ship’s crew plans to put the mooring into water exactly on the point, and then to release the upper part of the mooring, from the ADCP flotation buoy, with a releaser, leaving gently the ballast on the sea bottom.

02:33

After the three Vitrovex buoys with OGS releaser mod. IXSEA and ballast are hooked and raised to be placed in the water, a piece of Kevlar rope (blue line) broke and the 750kg ballast falls down from 1 meter height on the deck, together with the releaser from more than 6m height. Fortunately, there are no any consequences of this accident (Fig. 5.8). However, after falling the releaser appears compromised: some tests of functioning confirm that it is not working properly. Deployment operations are interrupted.

Fig. 5.8. Mooring line before and after the rope breaking (photo by C. Le Gall).

Fig. 5.9. Maintenance of the EDGETECH releaser: battery check (photo by M. Bensi).

16



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) To replace the IXSEA releaser, we decide to perform a last minute maintenance to the EDGETECH releaser (Fig. 5.9) recovered from water. However, the new battery pack taken on board by CNR-ISMAR team is not compatible with this model. Hence, batteries inside the instrument are measured (3.6V each, 18 batteries) and they seem still ok. After the permission by Captain and Chief scientist, we proceed with the S1 mooring deployment. We replace two pieces of mooring lines with a new Kevlar rope (from OGS). This time, the deployment will be done from the stern of the ship, to avoid too much load on the rope lines (Fig. 5.10). 04:15

Deployment Operations start again. Ship started moving slowly from 1.5 nautical miles distance from S1 site towards the point.

Fig 5.10. Preparing the mooring line for deployment on the stern of the ship (photo by C. Le Gall). 04:29

Flotation buoy in the water followed by RCM Seaguard s/n 1242.

04:34

Five vitrovex buoys in the water.

04:56

Sediment trap in the water followed by RCM 8 sn11162.

05:12

Three vitrovex buoys in the water.

05:14

Ballast in the water with parachute.

06:15

End of operation. S1 mooring release position and depth: Latitude 76° 26, 265’N; Longitude 13° 56,636’ E; Depth 1043m.

17




Fig. 5.11. Sketch of the mooring line deployed at S1.

18



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) I2 Mooring recovery operations: 13:45

The ship arrives at the I2 site. Several tentative of interrogation of the releaser fails (no answer from the releaser) even by using two deck units and two different cables.

14:09

We decide to send the release command to see if the releaser works even without answering. It works, and after interrogation, the depth is 865m. Then, the ship starts moving quickly far from the point.

14:16

I2 mooring surfaced in front of the ship.

14:50

I2 mooring line completely on board without any problem. The operations of cleaning and packaging of the instruments and ropes start. Due to the lack of time, we cannot do a tentative of mechanical recovery of mooring ID1 (‘lost’ after HH cruise in 2015 due to a releaser malfunction).

Fig. 5.12. Downloading of the data from recovered RCMs at I2 (left), and from ADCP at S1 (right), (photo by M. Bensi).

17:00

Data from I2 mooring downloaded: RCM instruments and thermistors. (Fig. 5.12)

15:15

CTD at site I2. Another two CTDs follow (stations DEF12 and DEF13). Water sampling only at I2 site, but without Winkler analysis because of the lack of time.

20:00

Sailing to Longyearbyen. 19




End of the packaging of all the scientific equipment and accessories into the container (BURSTER and DEFROST Teams).

Fig. 5.13. Sketch of the mooring line recovered at I2.

20




Fig. 5.14. The OGS container stored and closed on board on day 22 June 2016, few hours before the end of the cruise (photo by M. Bensi).

June 23, 2016, Thursday (Svalbard fjord, calm sea, moderate wind, cloudy, light spotty rain) 5:30

Arrival at the Longyearbyen Bay.

8:30

Disembark of part of the PS99.1 scientific/technical group and of all BURSTER and DEFROST Teams. Transfer to Hotels/Airport/etc. by local transport organized by the Agency in the harbor. Shipment of some equipment directly to Italy via carrier.

21



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) Group photo on Heli-deck during transfer (BURSTER and DEFROST TEAMS)

Fig. 5.15. Group photo on Heli-deck during transfer (BURSTER and DEFROST TEAMS)

22




WATER SAMPLING (ROSETTE)

CTD profiles during the downcast data were used to decide the depth of discrete sea water sampling for chemical and biological analyses, including salinity (by Autosal salinometer Guideline 8400b), pH (by pHmeter and spectrophotometer), total alkalinity (AT), dissolved oxygen (DO), dissolved inorganic carbon (DIC), hydrogen sulphide (H2S), carbon dioxide (CO2), methane (CH4), dissolved inorganic nutrients and abundance and diversity. Samples related to the DEFROST project were collected in proximity of S1 and I2 moorings. Samples for pH and total alkalinity were collected in 250 mL glass borosilicate bottles, immediately treated with 100 μL of saturated HgCl2 solution and stored at 4°C. Analyses of pH will be performed spectrophotometrically at the OGS laboratories by the SOP6b ver. 3.01 method (Dickson et al., 2007). The standard operative procedure for total alkalinity in seawater using open cell titration (Dickson et al., 2007) will be done. On board, pH analyses were performed by a potentiometric method (Grasshoff et al., 1983), using a WTW Inolab pH level 2 pHmeter. Samples used for dissolved oxygen analyses were collected in acid-cleaned and distilled-water rinsed 60 mL BOD bottles. Dissolved oxygen concentration was measured on board with a Mettler Toledo DL21 titrator for automated Winkler titration based on potentiometric end point detection, as detailed by Zoppini et al. (2010). Samples for DIC analyses were collected by overflow in 40 mL glass vials minimizing gas exchange with atmosphere, and immediately treated with 50 μL of 50% diluted HgCl2 solution in order to prevent biological activity and stored refrigerated until analyses. DIC will be determined using the Shimadzu TOC-V CSH Analyser injecting the sample into the instrument port and directly acidifying it with phosphoric acid (25%). Phosphoric acidification generates CO2 that is carried to a non-dispersive infrared detector (NDIR) (De Vittor et al. 2015; Kralj et al. 2015). Samples for dissolved inorganic nutrient analyses (NH4+, NO2-, NO3-, PO43– and Si(OH)4-) were pre-filtered on pre-combusted Whatman GF/F filters (0.7 μm, nominal porosity) and kept frozen (−20 °C) until laboratory analysis. Analyses will be carried out by means of a segmented flow Bran + Luebbe AutoAnalyzer 3 following standard colorimetric methods (Hansen and Koroleff, 1999). Samples for hydrogen sulphide determination were collected by overflow in 40 mL glass vials and preserved by adding 100 μL of zinc acetate solution. The samples will be measured spectrophotometrically using a VARIAN CARY 100 Scan spectrophotometer at 670 nm according to Fonselius (1983). Samples for dissolved gas analyses were collected by overflow in 40 mL amber glass vials minimizing gas exchange with atmosphere, and immediately treated with 50 μL of 50% diluted HgCl2 solution in order to prevent biological activity and stored refrigerated until analyses. The headspace technique will be used for the quantification of the partial pressure (pCO2, pCH4) of dissolved gases in water column samples (Capasso and Inguaggiato, 1998). 23




Tables 6. 1. Report the collected samples’ list collected during the PS99.1 cruise. Note that in this lists “GAS” refer to CO2 and CH4, whereas “B” and “S” in the column “Depth (m)” are respectively abbreviations for “Bottom water” and “Surface water”. PROJECT STATION Lat. N

Long. E

DEPTH (m) O2

pH/AT

pH on NUT board

NUT DIC vial

GAS

H2S

DEFROST

S1

76°26,159' 13°56,517' B=1032

X

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 1019

X

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 1013,8

X

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 900

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 801

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 650

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 400

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 250

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 125

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 49

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' 21

X

X

X

X

X

X

DEFROST

S1

76°26,159' 13°56,517' S

X

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' B=1017

X

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 1008

X

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 908

X

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 850

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 750

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 550

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 450

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 350

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 200

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 69

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' 15,6

X

X

X

X

X

DEFROST

I2

77°38,840' 10°16,850' S

X

X

X

X

X

MZP

24




Fig. 6.1. Chemical laboratory and instruments on board.

25



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) Salinity Analysis This page contains the results of the analyses performed at OGS-CTO laboratory (OGS calibration center) on the water samples collected on board to check salinity for quality control purposes. Water samples were collected in flint glass bottles with screw caps equipped with poly-seal cones to prevent leakages and evaporation. Samples procedures followed the international standard. Date: 09-10/11/2016 Ambient conditions:

Temperature: 21º C ± 1º C

Relative Humidity: 45% ± 10%

Test Equipment Instrument

Model

Autosal Salinometer

Guildline 8400B

S/N 65744

Notes: Laboratory Salinometer standardised using IAPSO Standard Sea Water (Batch n. P158) on 09/11/2016; Autosal Zero: 0.00001; Stand by: 21+6344/3; Sample ID Polar Stern 99.1_13-23 Jun 2016

“” “” “” “” “” “” “” “” “” “” “” “” “” “” “” “” “”

“” “” “” “” “” “” “” “” “” “” “” “” “” “” “” “” “”

Polar Stern 99.1_13-23 Jun 2016

Bottle Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Temp. (°C) 21 “” “” “” “” “” “” “” “” “” “” “” “” --“” “” “” “” “” “” “” “” “” “” “” “” “” “”

--“” “” “” “” 21

Salinity

Remarks

35.2640 35.0909 35.0386 35.0805 35.1249 34.9685 35.1151 --35.1027 34.9189 34.9375 34.9517 34.9565 34.9349 34.9132 --34.9114 34.9163 34.9174

Perdita per errata/scarsa chiusura del tappo Perdita per errata/scarsa chiusura del tappo Perdita per errata/scarsa chiusura del tappo Perdita per errata/scarsa chiusura del tappo

Perdita per errata/scarsa chiusura del tappo

Measurements performed by: NM - CC Approved by: N. Medeot, CTMO Unit

26




PRELIMINARY RESULTS

The preliminary results of the PS99.1 cruise include CTD casts (vertical and horizontal distribution of hydrological properties), time-series from moorings S1 and I2, and chemical analyses taken on board (Dissolved Oxygen). Results refer to the DEFROST activities. 7.1 CTD casts A total number of nine (9) CTD casts were performed along two cross-section (Fig. 7.1.1). A comparison between the two TC sensors (Fig. 7.1.2) shows why at least for the preliminary results our choice is the secondary pair of sensors: their performance seems to be more stable and less noisy. As far as the SBE 43 oxygen sensor is concerned, its performance was often as shown in Fig. 7.1.2, with a sudden offset at a certain depth during downcast (in this case at 700m depth). This offset remains during downcast. Therefore, by means of a Winkler derived dissolved oxygen data we will try to establish the most possible correct behavior of this sensor. Preliminary results are shown in figures 7.1.3, 7.1.4, and 7.1.5.

Fig. 7.1.1. DEFROST study area (on the left): Red dots and black diamonds indicate CTD casts and moorings (S1 and I2) positions, respectively. Dashed lines indicate the main current patterns in the area. In the right panel, more details of the CTD stations distribution in the working area. The color scales on the right of both panels refer to the bathymetry.

27




Fig. 7.1.2. An example of the downcast (dark colors) and upcast (pale colors) obtained by the two couple of TC sensors, and by a SBE 43 dissolved oxygen sensor.

Fig. 7.1.3. θ-S diagram of the CTD profiles carried out during DEFROST activities (a). Bottom distribution of S (b) and DO (c) in the moorings areas.

28




Fig. 7.1.4. Vertical section in the southern DEFROST area.

Fig. 7.2.5. Vertical section in the northern DEFROST area. 29



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) 7.2

Biochemical samples taken on board

Preliminary results of the water sample analyses are shown in Table 7.2.1 and Fig. 7.2.1. Some analyses on samples that were stored on board at 4° and -20°C are still in progress and cannot be included in this cruise report.

Table 7.2.1. Results of analysis of dissolved oxygen performed during PS99.1 cruise (DEFROST project). “B” and “S” in the column called “Depth” are respectively abbreviations for “Bottom water” and “Surface water”. Date

Project

Station

Depth (m)

DO (mmol/L)

DO (mL/L)

21/06/2016

DEFROST

S1 MOORING

B=1032

260,94

5,849

21/06/2016

DEFROST

S1 MOORING

1019

299,44

6,712

S1 MOORING

1013,8

300,21

6,729

21/06/2016

DEFROST

21/06/2016

DEFROST

S1 MOORING

900

301,52

6,758

21/06/2016

DEFROST

S1 MOORING

801

305,44

6,846

21/06/2016

DEFROST

S1 MOORING

650

291,72

6,539

S1 MOORING

400

309,68

6,941

21/06/2016

DEFROST

21/06/2016

DEFROST

S1 MOORING

250

312,03

6,994

21/06/2016

DEFROST

S1 MOORING

125

307,96

6,903

21/06/2016

DEFROST

S1 MOORING

49

315,22

7,065

S1 MOORING

21

338,54

7,588

S1 MOORING

S

339,10

7,601

21/06/2016 21/06/2016

DEFROST DEFROST

30



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) DEFROST Station S1 Dissolved Oxygen 0

4.0

5.0

6.0

Conc. (mL L-1) 7.0

8.0

80 160 240 320

Depth (m)

400 480 560 640 720 800 880 960 1040

Fig. 7.2.1. Dissolved oxygen profile from discrete samples collected at S1 site and analysed with Winkler method. 7.3 Mooring data (time-series) Preliminary data gathered from moorings S1 and I2 are presented here. They refer to the deployment 2014-2015 and to the deployment 2015-2016. Time series started in June 2014 after the EUROFLEET2 - PREPARED cruise. 7.3.1

Thermohaline and sediment traps data

Thermohaline variability at mooring S1 referred to the period 2014-2016 is shown in figure 7.3.1. We note an enhanced variability in θ and S between October and May in both years, more evident during winter 2015 than during winter 2016. After a preliminary analysis, it seems associated to cascading events. However, it is interesting to note that these pulsations are less dense (warmer and saltier) than the ambient water. Turbidity increases at the end of the winter phase, but its peaks do not seem always associated with θ and S ones. Some questions arise from these preliminary data: NSDW (Norwegian Sea Deep Water) appears to be the stable signal (-0.9 °C; 34.91; 28.7 kg/m3), while it is not very clear what the frequent intrusions of less dense waters are referred to. Again, we are wondering how is it possible that less dense water (even of Arctic shelf origin) could penetrate towards the abyss. Is it because it is embedded in sediment fluxes? Further analyses on the scientific results, which will be presented in a journal article, will clarify this aspect.

31




Fig. 7.3.1. θ, S, turbidity collected at S1 mooring between 2014 and 2016. Grey lines indicated the time when maintenance cruises have been carried out (from Bensi et al., 2016). Thermohaline variability at mooring I2 is shown in figure 7.3.2. A qualitative comparison with data collected at S1 reveals that some episodes are coincident; further analyses, such as cross-correlation will possibly highlight time lags between common events at the two moorings. Time series from both moorings have been compared with data extracted from CTD casts in the proximity of the fixed sites, and the preliminary results revealed that the collected data are qualitatively good (see fig. 7.3.2 as example, referred to mooring I2).

32




Fig. 7.3.2. θ, S collected at I2 mooring between 2014 and 2015. Blue asterisks indicate data extracted from CTD casts in proximity of the mooring. From June 2015 until June 2016, CT sensors were substituted with simple thermistors, hence only in-situ temperature is available (not shown here).

As far as the sediment trap at S1 is concerned, only partial data are available up to now, because some analyses are still in progress. However, it must be said that the sediment trap rotation failed after the fifth sample after June 2014. Thus, from mid-August 2014 until June 2015, we have only an integrated sample. Nevertheless, some considerations can be done: Total Mass Fluxes (TMF) vary between 88 and 326 mg m-2 d-1. They are lower in summer (Fig. 7.3.3), while in winter, they increase during the episodes of current strengthening, confirming the contribution of bottom currents in transferring particles from the shelf toward the deep basin. The winter sample is characterized by low contents of OC (Organic Carbon) and total nitrogen, and more negative δ13C values (higher terrestrial OC fraction). The high contents of CaCO3 (17-27%), also in winter, suggest an important contribution of detrital carbonates. In summer, fresh organic matter (OC > 4%) composed by phytoplanktonic detritus is characterized by less negative δ13C values (higher marine OC fraction) and lower values of δ15N due to the influence of relatively nutrient-enriched surface waters (Langone et al., 2016).

33




Fig. 7.3.3. Time series of total mass fluxes plotted against biogenic components and stable isotopes of organic matter from June 2014 to June 2015 (Langone et al., 2016). Samples collected in June 2016 (PS99 cruise) referred to the period June 2015- June 2016 are still to be analysed. 7.3.2

Current data

Current data have been first cleaned for outliers and spikes and then filtered out with a 33h filter that removes tides and inertial signal (period about 12.3 h). In the analysis, each cell of the ADCP has been treated as an independent single-point current-meter. S1 mooring ADCP (Acoustic Doppler Current Profiler), downward-looking, was set to measure 32 cells of 5 m, i.e. 160m length. The last 6 cells are beyond the water column range and therefore have been discarded. Sampling time was set to half an hour (30 minutes).

34




Fig. 7.3.4. ADCP lowpass currents for the upper 16 cells (deployment 2014-2015) and 18 cells (deployment 2015-2016).

Aanderaa current meter RCM8 was positioned below the sediment trap about 20m above the seafloor. The data have been collected with a sampling rate of 1 hour.

Fig 7.3.5. Lowpass currents for Aanderaa current-meter at S1, positioned below the sediment trap and 20m above the seafloor.

35



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) Table 7.3.1. Lowpass current statistic values (in cm/s).

20142015 20152016

S1

U mean

V mean

minU/maxU

minV/maxV Mean speed

speed min/max

ADCP 908m

-0.89+/-9.16

2.47+/-10.19

-40.5 / 38.1

-44.0 / 40.9

11.26+/-8.24

0 / 55.1

Current-meter

0.53+/-10.38

3.80+/-8.25

-29.1 / 58.1

-27.2 / 35.9

10.63+/-8.81

0.1 / 63.0

ADCP 908m

-0.82+/-7.91

2.33+/-8.53

-33.9 / 39

-22.9 / 38.5

10.14+/-6.23

0.1 / 50.5

Current-meter

-0.21+/-7.95

3.49+/-7.27

-31.3 / 33.8

-14.8 / 29.9

9.45+/-6.24

0.1 / 42.6

I2 mooring Aanderaa current-meters RCM4 (s/n 1654) and RCM9 (s/n 183) collected data with sampling rate of 1 hour and 2 hours respectively. RCM4 was positioned about 15 m above the seafloor (echo depth: 1063m), while RCM9 was positioned 105m above the RCM4.

Fig. 7.3.6. Lowpass currents for upper current-meter (RCM9 s/n. 183) at I2.

Fig. 7.3.7. Lowpass currents for lower current-meter (RCM4 s/n. 1654) at I2.

36




Table 7.3.2. Lowpass current statistic values (in cm/s).

20142015

20152016

I2

U mean

V mean

minU/maxU

minV/maxV Mean speed

speed min/max

Upper currentmeter-RCM9

-6.27+/-7.72

7.60+/-9.03

-34.3 / 29.5

-30.8 / 35.6

12.67+/-8.82

0.1 / 49.3

Lower currentmeter-RCM4

-9.28+/-9.40

6.74+/-7.90

-34.2 / 31.2

-20.6 / 36.6

14.06+/-9.21

0.1 / 50.0

Upper current- -5.47+/-6.77 meter-RCM9

6.19+/-7.82

-35.5 / 16.5

-20.3 / 43

10.63+/-7.90

0.1 / 55.8

Lower currentmeter-RCM4

4.68+/-5.58

-41.3 / 28.4

-13.7 / 27.6

11.96+/-8.20

0.1 / 46.97

-6.53+/-10.7

ADCP-VM (Vessel mounted) data Polarstern ship was equipped with an OS 150 kHz ADCP-VM (Acoustic Doppler Current Profiler Vessel Mounted, Teledyne RDI manufacturer) operating in narrow band mode and which measured horizontal currents along the water column below the ship hull. Currents were measured along the shiptrack in the uppermost part of the water column. The ADCP is a medium water system whose maximum depth was about 335 m; it was set to measure currents within 80 cells of 4 m each, starting from 19 m depth. The GPS positioning data, Heading, Pitch and Roll data was available on a serial port and were used to re-project currents (along-track and across-track components) into the north and east directions. Time averages over 20 minutes (LTA) were used for the processing. The complete data set was then processed

with

the

CODAS3

software

(University

of

the

Hawaii;

http://currents.soest.hawaii.edu/docs/doc/codas_doc/index.html ) in order to edit, geo-reference, and interpolate it over a regular spatial grid. Mean speeds, calculated for each level, are always higher than 15 cm/s in the upper 300 m depth.

37




Fig. 7.3.8. Data processed from ADCP-VM along the ship’s track and referred to 23m depth.

8

ACKNOWLEDGMENTS

Thanks are due to the Captain of the I/B Polastern Thomas Wunderlich, to the Polarstern Officers and the Crew for their professionalism and kindness during our stay on board. Special thanks goes to the Chief scientist Thomas Soltwedel for his punctuality during the cruise preparation and his professionalism during the Polarstern expedition, other than for his kindness. The DEFROST project is funded within the Italian PNRA (Programma Nazionale di Ricerca in Antartide): the project was approved in November 2015, and the activities are planned in the biennium 2016-2017. The collaboration with the EUROFLEETS-2 Cruise BURSTER (see Lucchi et al., 2016, OGS Report 2016/85 Sez. GEO 11 GEOS, Bottom Currents in a Stagnant Environment – BURSTER, available at http://www2.ogs.trieste.it:8585/biblioteca/index.php?option=com_relazioni&Itemid=110)

was

essential for the feasibility of the DEFROST activities.

38




REFERENCES

Bensi M., V. Kovacevic, M. Rebesco, L. Ursella, D. Deponte, L. Langone, S. Aliani, S. Miserocchi, A. Wåhlin, T. Soltwedel, I. Goszczko, R. Skogseth (2016). Preliminary results of the oceanographic features of the bottom density-driven currents on the Storfjorden continental slope (Svalbard), ARCA final conference, Rome (Italy), 11 Oct. 2016. Capasso G., Inguaggiato S. (1998), A simple method for the determination of dissolved gases in natural waters. An application to thermal waters from Vulcano Island. Applied Geohemistry, 13(5): 631-642. De Vittor C., Relitti F., Kralj M., Covelli S, Emili A. (2015), Oxygen, carbon, and nutrient exchanges at the sediment–water interface in the Mar Piccolo of Taranto (Ionian Sea, southern Italy). Environmental Science and Pollution Research, 23 12566–12581. Dickson A.G., Sabine C.L., Christian J.R. (2007), SOP 3b Determination of total alkalinity in seawater using an open-cell titration, ver. 3.01. In: Dickson AG, Sabine CL, Christian JR (eds) Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 p. Fonselius S. (1983), Determination of hydrogen sulphide. Methods of Seawater Analysis (GrasshoffK, EhrhardtM & KremlingK, eds), pp. 73–80. Verlag Chemie, Weinheim, Germany. Grasshoff K., Ehrhardt M., Kremling K. (1983,) Methods of seawater analysis, 2nd edn. Wienheim, Verlag Chemie. Hansen H.P., Koroleff F. (1999), Determination of nutrients, in: Grasshof K, Erhardt M, Kremling K (eds), Methods of seawater analysis, 3rd edn. Wiley-VCH, Weinheim pp. 159-228. Jakobsson, M., et al. (2012). The International Bathymetric Chart of the Arctic Ocean (IBCAO) Version 3.0. Geophysical Research Letters 39, L12609, doi: 10.1029/2012GL052219. Kralj M., De Vittor C., Comici C., Relitti F., Auriemma R., Alabiso G., Del Negro P. (2015), Recent evolution of the physical–chemical characteristics of a Site of National Interest—the Mar Piccolo of Taranto (Ionian Sea)—and changes over the last 20 years. Environmental Science and Pollution Research, 23 12675–12690. Langone L., S. Aliani, A. D'Angelo, F. Giglio, S. Miserocchi, M. Bensi, V. Kovacevic, M. Rebesco, L. Ursella, D. Deponte, A. Wåhlin.Temporal variability of particle fluxes and bottom density-driven currents on the Storfjorden continental slope (Svalbard), ARCA final conference, Rome (Italy), 11 Oct. 2016. Lucchi R. G., Bazzaro M., Biebow N., Carbonara K., Caridi F., Deponte D., De Vittor C., Dominiczak A., Gamboa Sojo V.M., Graziani S., Kovacevic V., Krueger M., Le Gall C., Mazzini A,. Morigi C., Musco M. E., Povea P., Relitti F., Ruggiero L., Rui L., Sabbatini A., Sànchez Guillamòn O., 39



PS99.1 CRUISE: 13-23 June 2016 (PNRA-DEFROST/Eurofleets2-BURSTER) Tagliaferro M., Topchiy M., Wiberg D., Zoch D., Bensi M., Langone L., Laterza R. (2016). Bottom Currents in a Stagnant Environment (BUSTER), 2016/85 Sez. GEO 11 GEOS. Rebesco, M., et al. (2013). Quaternary contourite drifts of the Western Spitsbergen margin. Deep-Sea Research I, 79, 156-168, doi:10.1016/j.dsr.2013.05.013. Zoppini A., Azzaro M., Del Negro P., La Ferla R., Pugnetti A. (2010) Respirazione planctonica, in: Socal G, Buttino I, Cabrini M, Mangoni O, Penna A, Totti C (Eds), Metodologie di studio del plancton marino. ISPRA, settore editoria, pp. 185-19.

40

