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Total aluminium and lead content in eastern Mediterranean rainwaters
J Aerosol Sci. Vol. 31, Suppl. I, pp. $753-$754,2000
Pergamon www.elsevier.com/locate/jaerosci
Poster Session II. Atmospheric aerosols: elemental composition TOTAL ALUMINIUM AND LEAD CONTENT IN EASTERN MEDITERRANEAN RAINWATERS
U. EZAT Laboratoire des Sciences du Climat et de l'Environnement Unit6 Mixte de Recherche CEA-CNRS 1572 91190 Gif sur Yvette Cedex France.
Keywords: eastern mediterranean, rainwater, monthly flux, aluminium, lead. INTRODUCTION Occurrence of red rains and colored dust from Africa are well-known in France and Europe. They are important components of atmospheric inputs reaching the Mediterranean Sea. The aim of this work is to evaluate the wet deposition of aerosols of different origins to the eastern Mediterranean Sea. Here, we present results on mineral dust and lead content in rainwater samples collected in Greece. More than 200 rainwater samples were sampled and investigated for aluminium (AI) and lead (Pb) concentrations. Two sampling sites in Crete were selected for this study: one in Finokalia (25 ° 40'E35°20'N) located on the seashore in a rural site, the other one in Heraklion, the major city of Crete (25°60'E-35°24'N)(Greece). METHODS After measuring the pH of each sample, several drops of chloroform were added to avoid fungus and microbial development and kept cold until analyses. Aliquots of a few milliliters of rainwater were analyzed by electrothermal atomic absorption (Zeeman 3030, P-E Spectrometer) for the determination of total aluminium (AI) and lead (Pb) concentrations. The precision is better than 5% for both elements and detection limits are 0.5 ~tg/1 for AI and 0.05 ~tg/l for Pb (Ezat et al 1997). RESULTS AND DISCUSSION AI was used as a tracer of mineral aerosols generated from soil erosion by winds and Pb as a tracer of anthropogenic contaminations. AI concentrations vary by about three orders of magnitude. Over the sampling period, the mean concentration of AI at Heraklion station is 0.50 mg/l, covering a range of 0.02 - 19.07 mg/l. At Finokalia station mean AI concentration is comparable, 0.60 mg/l, spanning a range from 0.13 to 5.50 mg/l. Dust flux were calculated assuming that AI represents about 8% of alumino-silicates. The mean monthly flux of the wet deposition is 44.03 mg/m2/month at the Finokalia and 37.55 at Heraklion. The annual wet deposition flux is 2.7 g/m2/year at Finokalia, and 2.2 g/m/year at Heraklion. Total dust flux (wet + dry depositions) was estimated by Nihl6n et al. (1995) to be 21.3 g/m2/year. Pb concentrations vary by two orders of magnitude. Pb mean concentration was 0.01 mg/i over two years in Heraklion rainwaters and 0.01 mg/l over one year in Finokalia rainwaters. Pb flux was 4.40 mg/m2/year at Finokalia and 4.85 mg/m2/year at Heraklion. Figures 1 a and b display monthly AI and Pb fluxes at both sampling stations, in 1997.
m~/mZ/month
$753
$754
Abstracts of the 2000 EuropeazlAerosolConft.'rellcc
AI
Pb
800
3O00 []
Finokalia
•
Heraklion
2500
[]
Finokalia
•
HerakZion
1500 N
N lO~ 200.
o,
• 1
. 2
3
4
5
6
,-7
8
7
0 . 9
I0
Ii
12
.
.
1
2
.
. 3
Month number
. 4
r'n . 5
6
I-1. 7
8
. 9
10
11
12
Month number
Figures: 1 Mean monthly fluxes of (a) aluminium mg/m2/month and (b) lead in I.tg/mZ/month at Finokalia and Heraklion sampling stations Figure la show a strong seasonality of A1 and Pb fluxes over the year 1997. I can be seen from Figure la that AI dust transport is more important during winter and fall months while fluxes reach their lowest levels in summer, as previously reported by Ezat et al. (1997). The examination of meteorological data averaged over several years show that air masses originate quite frequently from Northern African. Therefore, air dust from the Sahara is likely responsible for the AI supply to our sampling sites. Analyses of other elements in our samples (ionic balance) are consistent with mineral dust originating mostly from North Africa, Mihalopoulos. N et al (1997). Pb monthly fluxes at both sampling stations (Figure lb) indicate similar seasonal flux pattern. However, in winter Pb fluxes are high at Heraklion than at Finokalia. This result likely reflects higher anthropogenic emissions in the urban site of Heraklion, while Fenokalia fluxes are consistent with lower contamination levels of rural sites. In contrast, November and December Pb fluxes are higher at Finokalia than Heraklion. A contribution from other sources, possibly from continental Greece, may be responsible for such levels, but air mass back trajectories would be necessary to confirm this interpretation. ACKNOWLEDGEMENTS This work was supported by CNRS-CEA and European Environment and Climate Program contract n-o ENV4-CT95-0036. The author is very grateful to M.A Sicre, M. H Z. Haider and H. Sarabi for their kind helps and their advices. REFERENCES Ezat, U et al (1997). Dust and lead in rainwaters of Crete, J Aerosol Sci. Suppi 1, PP: 579-580. Mihalopoulos. N et al (1997). Tropospheric ionic composition in the Eastern Mediterranean region. Tellus, vol 49B, pp: 314-326. Nihl6n. T et ai (1995). Monitoring of Saharan dust fallout on Crete and its contribution to soil formation. Tellus, 45B, pp: 365-374.
Pergamon www.elsevier.com/locate/jaerosci
Poster Session II. Atmospheric aerosols: elemental composition TOTAL ALUMINIUM AND LEAD CONTENT IN EASTERN MEDITERRANEAN RAINWATERS
U. EZAT Laboratoire des Sciences du Climat et de l'Environnement Unit6 Mixte de Recherche CEA-CNRS 1572 91190 Gif sur Yvette Cedex France.
Keywords: eastern mediterranean, rainwater, monthly flux, aluminium, lead. INTRODUCTION Occurrence of red rains and colored dust from Africa are well-known in France and Europe. They are important components of atmospheric inputs reaching the Mediterranean Sea. The aim of this work is to evaluate the wet deposition of aerosols of different origins to the eastern Mediterranean Sea. Here, we present results on mineral dust and lead content in rainwater samples collected in Greece. More than 200 rainwater samples were sampled and investigated for aluminium (AI) and lead (Pb) concentrations. Two sampling sites in Crete were selected for this study: one in Finokalia (25 ° 40'E35°20'N) located on the seashore in a rural site, the other one in Heraklion, the major city of Crete (25°60'E-35°24'N)(Greece). METHODS After measuring the pH of each sample, several drops of chloroform were added to avoid fungus and microbial development and kept cold until analyses. Aliquots of a few milliliters of rainwater were analyzed by electrothermal atomic absorption (Zeeman 3030, P-E Spectrometer) for the determination of total aluminium (AI) and lead (Pb) concentrations. The precision is better than 5% for both elements and detection limits are 0.5 ~tg/1 for AI and 0.05 ~tg/l for Pb (Ezat et al 1997). RESULTS AND DISCUSSION AI was used as a tracer of mineral aerosols generated from soil erosion by winds and Pb as a tracer of anthropogenic contaminations. AI concentrations vary by about three orders of magnitude. Over the sampling period, the mean concentration of AI at Heraklion station is 0.50 mg/l, covering a range of 0.02 - 19.07 mg/l. At Finokalia station mean AI concentration is comparable, 0.60 mg/l, spanning a range from 0.13 to 5.50 mg/l. Dust flux were calculated assuming that AI represents about 8% of alumino-silicates. The mean monthly flux of the wet deposition is 44.03 mg/m2/month at the Finokalia and 37.55 at Heraklion. The annual wet deposition flux is 2.7 g/m2/year at Finokalia, and 2.2 g/m/year at Heraklion. Total dust flux (wet + dry depositions) was estimated by Nihl6n et al. (1995) to be 21.3 g/m2/year. Pb concentrations vary by two orders of magnitude. Pb mean concentration was 0.01 mg/i over two years in Heraklion rainwaters and 0.01 mg/l over one year in Finokalia rainwaters. Pb flux was 4.40 mg/m2/year at Finokalia and 4.85 mg/m2/year at Heraklion. Figures 1 a and b display monthly AI and Pb fluxes at both sampling stations, in 1997.
m~/mZ/month
$753
$754
Abstracts of the 2000 EuropeazlAerosolConft.'rellcc
AI
Pb
800
3O00 []
Finokalia
•
Heraklion
2500
[]
Finokalia
•
HerakZion
1500 N
N lO~ 200.
o,
• 1
. 2
3
4
5
6
,-7
8
7
0 . 9
I0
Ii
12
.
.
1
2
.
. 3
Month number
. 4
r'n . 5
6
I-1. 7
8
. 9
10
11
12
Month number
Figures: 1 Mean monthly fluxes of (a) aluminium mg/m2/month and (b) lead in I.tg/mZ/month at Finokalia and Heraklion sampling stations Figure la show a strong seasonality of A1 and Pb fluxes over the year 1997. I can be seen from Figure la that AI dust transport is more important during winter and fall months while fluxes reach their lowest levels in summer, as previously reported by Ezat et al. (1997). The examination of meteorological data averaged over several years show that air masses originate quite frequently from Northern African. Therefore, air dust from the Sahara is likely responsible for the AI supply to our sampling sites. Analyses of other elements in our samples (ionic balance) are consistent with mineral dust originating mostly from North Africa, Mihalopoulos. N et al (1997). Pb monthly fluxes at both sampling stations (Figure lb) indicate similar seasonal flux pattern. However, in winter Pb fluxes are high at Heraklion than at Finokalia. This result likely reflects higher anthropogenic emissions in the urban site of Heraklion, while Fenokalia fluxes are consistent with lower contamination levels of rural sites. In contrast, November and December Pb fluxes are higher at Finokalia than Heraklion. A contribution from other sources, possibly from continental Greece, may be responsible for such levels, but air mass back trajectories would be necessary to confirm this interpretation. ACKNOWLEDGEMENTS This work was supported by CNRS-CEA and European Environment and Climate Program contract n-o ENV4-CT95-0036. The author is very grateful to M.A Sicre, M. H Z. Haider and H. Sarabi for their kind helps and their advices. REFERENCES Ezat, U et al (1997). Dust and lead in rainwaters of Crete, J Aerosol Sci. Suppi 1, PP: 579-580. Mihalopoulos. N et al (1997). Tropospheric ionic composition in the Eastern Mediterranean region. Tellus, vol 49B, pp: 314-326. Nihl6n. T et ai (1995). Monitoring of Saharan dust fallout on Crete and its contribution to soil formation. Tellus, 45B, pp: 365-374.