Environ Monit Assess (2008) 136:209–218 DOI 10.1007/s10661-007-9676-4
Atmospheric deposition of major and trace elements in Amman, Jordan Idrees F. Al-Momani & Kamal A. Momani & Qasem M. Jaradat & Adnan M. Massadeh & Yaser A. Yousef & Ahmed A. Alomary
Received: 11 October 2006 / Accepted: 23 February 2007 / Published online: 17 March 2007 # Springer Science + Business Media B.V. 2007
Abstract Wet and dry deposition samples were collected in the capital of Jordan, Amman. Concentrations of Al, Ba, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, Zn, Fe, Sr, Mg2+, Ca2+, Na+, K+, Cl−, NO3− and SO42−, along with pH were determined in collected samples. Mean trace metal concentrations were similar or less than those reported for other urban regions worldwide, while concentrations of Ca2+ and SO42− were among the highest. High Ca2+ concentrations were attributed to the calcareous nature of the local soil and to the influence of the Saharan dust. However, high SO42− concentrations were attributed to the influence of both anthropogenic and natural sources. Except for Cl−, NO3−, SO42− and Cu, monthly dry deposition fluxes of all measured species were higher than wet deposition fluxes. The annual wet
I. F. Al-Momani (*) : Y. A. Yousef : A. A. Alomary Chemistry Department, Yarmouk University, Yarmouk Street, Irbid 00461, Jordan e-mail:
[email protected] A. M. Massadeh Department of Medicinal Chemistry and Pharmacognosy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan K. A. Momani : Q. M. Jaradat Chemistry Department, Mutah University, Al-Karak, Jordan
deposition fluxes of trace metals were much lower than those reported for other urban areas worldwide. Keywords Wet deposition . Dry deposition . Major ions . Metals . Fluxes . ICP-MS
Introduction Atmospheric concentrations of many trace elements have been significantly affected by man's activities. Due to their diverse effects, the importance of quantification of trace elements in wet and dry atmospheric depositions has been shown by several authors (Heaton et al. 1990; Kaya and Tuncel 1997; Al-Momani et al. 2002). In addition, the analysis of trace species in different environmental samples is of particular important because certain species are emitted from particular source types and they can be used as tracers for these sources (Heaton et al. 1990; Dasch and Wolff 1989; Dutkiewicz et al. 1987). The use of ICP-MS technique has shown powerful possibilities to measure a wide range of trace elements at very low concentrations. A number of data obtained by ICP-MS were recently published in rain by Berg et al. (1994) in Norway, Atteia (1994) in Switzerland, Al-Momani (2003) in Jordan. Amman is the capital of Jordan (population > one million) and has considerable light industries. More than 150,000 motor vehicles circulate in Amman each
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working day. During the winter months, kerosene is mainly used for domestic heating. The city is located on the Northern part of Jordan and is subjected to the eastern Mediterranean weather regime. The primary objectives of our study were to estimate the deposition of selected pollutants from the air directly to the surface and to the terrestrial ecosystem in Amman and to compare wet and dry deposition fluxes for selected species.
Methods and materials Sampling Wet and dry deposition samples were collected from November 1999 to March 2000. The sampling station was located in the capital of Jordan, Amman. Amman is the largest city in Jordan and surrounded by some light industries. The station was about 150 m from the highway connecting the largest two cities in Jordan, Amman and Zarqa. Samplers were installed on the roof of one of the buildings at a height of about 12 m above the ground. Wet deposition samples were collected using a 22 cm diameter of high-density Polyethylene funnel connected to a neck-screwed receiving bottle. All rainwater samples were collected in daily base. The sampling device was washed twice daily to avoid dry deposition. After collection, the bottles were reweighed to obtain a measure of precipitation volume and the pH was measured. Samples with less than 1-mm of rain were discarded and not analyzed chemically. A fraction of each sample (10 ml) was taken and filtered through 0.45 μm and used for the determination of major anions by ion chromatography. The remaining fraction was acidified by superpure nitric acid (0.5 ml/100 ml sample) and used for cations analysis (Al, Ba, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, Zn, Fe, Sr, Mg, Ca, Na and K) by ICP-AES and ICP-MS. Eighteen daily rainwater samples, corresponding to about 70% of the total annual rainfall amount were collected during the study period. Such sampling procedures allowed the dissolution of the acid-soluble fraction of particles which mainly comes from anthropogenic activities (Colin et al. 1990; Desboeufs et al. 2001; Sandroni and Migon 2002). The crustal elements contained in the insoluble fraction have not been considered in this paper.
Environ Monit Assess (2008) 136:209–218
Dry deposition samples were collected every 15 days using high-density Polyethylene containers (30 cm diameter). Various kinds of apparatuses, such as plates and buckets have been used to measure atmospheric deposition of chemicals, including nutrients and toxic substances. However, due to the complexity of the environment, none appears to accurately simulate real atmospheric deposition. The bucket method was selected in this study because it has been used in many studies, such as the National Atmospheric Deposition Program (NADP), at more than 200 sites in the US (Zheng et al. 2005). After each sampling period, the container was washed by a total of 100 ml deionized water then the washing was transferred into a dry and clean Polyethylene bottle and the pH was measured. A fraction of each sample (10 ml) was taken and filtered through 0.45 μm and used for the determination of major anions by ion chromatography. The remaining fraction was acidified by adding 1 ml of redistilled nitric acid and used for cations analysis.
Chemical analysis The pH values of the collected samples were measured for un-acidified fractions using JENWAY pH-Meter 3320 equipped with a combination glasselectrode. Concentration of NH4+ was determined spectrophotometrically using Nessler method. Unacidified fractions of wet and dry deposition samples were analyzed for Cl−, NO3− and SO42− by ion chromatography using a Dionex-100, equipped with AG4A-SC guard column, AS4ASC separating column, SSR1 anion self regenerating suppressor and conductivity detector. Samples were injected through 25-μl sample loop and eluted at 2.0 ml/min using Na2CO3/ NaHCO3 in milli-Q water. A 4400 integrator collected data from Dionex. The corresponding peak areas of ions were then used to calculate concentrations. Detection limits of the anions, concentrations corresponding to three times the standard deviation of ten replicate blank level measurements, were 0.07 μg ml−1 for Cl−, 0.20 μg ml−1 for NO3−, and 0.60 μg ml−1 for SO42−. Both Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) were used to analyze acidified samples for major cations and trace metals. Samples were firstly analyzed by ICP-OES
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(Perken Elmer, Model Optima-2000) at Carleton University (Ottawa, CANADA). Since concentrations of some trace metals in rainwater samples were not detected by ICP-OES, samples were analyzed by ICPMS (Perken Elmer, Model Elan-6000) at the laboratories of the Geological Survey of CANADA, Ottawa. Detection limits corresponding to three times the standard deviation of ten replicate blank level measurements, were 0.09 μg ml−1 for Na+, 0.02 μg ml−1 for K+, and 0.06 μg ml−1 for Mg2+, 0.11 μg ml−1 for Ca2+, 0.04 μg ml−1 for Cd, and below 0.2 μg ml−1 for the rest of the remaining trace metals.
generate comparable data. Analytical precision of species measurements was determined by replicate measurements on separate aliquots of a representative number of samples. The relative standard deviations were calculated to determine the precision of the analysis. The overall precision was ±10% for Zn, Ni and Cr and ±5% for all rest of the measured species.
Quality control and assurance
A statistical summary for the measured chemical species (Mg2+, Ca2+, Na+, K+, Cl−, NO3−, SO42−, Al, Ba, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, V, Zn, Fe, and Sr) is presented in Table 1. Average, standard deviation, maximum and minimum concentrations were all presented in the table. The last four columns containing literature data for comparison of the concentrations of measured species with those found worldwide from comparable sites. The data in the table reveals that concentrations of major ions (Mg2+, Ca2+, Na+, K+, Cl−, NO3−, SO42−) in this study are much higher than those reported for Western Massachusetts and Ankara and close to those reported for the Eastern Mediterranean coast. These high concentrations for crustal elements are partially attributed to the increased human activities, especially construction activities. In addition, the dissolution of Saharan dust particles, which is rich by calcite, dolomite, gypsum, etc., may also contribute to the observed high concentrations of Ca2+, Mg2+, K+ and SO42−. Therefore, high SO42− concentrations in our samples can be attributed to the influence of both anthropogenic emissions and the dissolution of Saharan dust particles. This phenomenon has been usually reported in the region by several authors (Herut et al. 2000; LoyePilot and Morelli 1988). Loye-Pilot et al. (1986), who analyzed wet fall in conjunction with dust storms on the island of Corsica, reported that Saharan dust associated with “red rain” have high pH values and high concentrations of Ca2+ and SO42−. Based on back-Trajectory calculations, Glavas and Moschonas (2002) have found that samples collected from the North Africa sector had high concentrations of SO42−. Similar results have also been reported in Spain by Avila and Alarcon (1999), and nearby in Israel
Precautions were taken to avoid contamination of samples in both field and laboratory, and to ensure the reliability of our determinations. Prior to installation, the funnel and collection bottles were carefully cleaned and dried in a clean laboratory. After each precipitation event, the collection bottles were removed and replaced with others that had undergone the washing procedure. Similarly, field blanks for dry deposition samples were taken by washing the clean Polyethylene containers by deionized water. Except for Zn, V, Bi and Cr, the sample-to-blank ratios (field blank) for measured elements were larger than 3, indicating that blank subtraction does not have a significant contribution on the observed concentrations. The sample-to-blank ratios for Zn, V, Bi and Cr were 2.3, 2.6, 2.1 and 2.8, respectively. The accuracy of the methods was evaluated by periodic analysis of Standard Reference Materials (SRMs) obtained from the National Institute of Standards and Technology (NIST). SRM 2704 and SRM 1646 were analyzed along with samples. Observed concentrations were within 3% of certified values in analyzed SRMs for Zn, V, Ni, Sb and Fe, within 6% for Ti, As, Pb, Mg, K and Cu, and within 10% for the remaining elements. Elements with percentage errors of >11% and sample-to-blank ratio
