Trace elements in the North Atlantic troposphere: Shipboard results of precipitation and aerosols

Global Biogeochemical Cycles - Tập 4 Số 4 - Trang 431-443 - 1990
Thomas M. Church, Alain Véron, Clair C. Patterson, Dorothy M. Settle, Yigal Erel, H. R. Maring, A. Russell Flegal

Tóm tắt

Samples for trace metals in precipitation (rain, snow, and fog) and total aerosols were collected at sea as part of the GCE/CASE/WATOX expedition during August and September 1988 in the greater North Atlantic between Bermuda, Iceland, the Azores, and Barbados. The samples were collected using ultra‐clean equipment and methods for the analysis of the trace elements Al, Fe, Mn, Zn, Cu, Ni, Cd, and Pb (including stable isotopes). The samples were analyzed by graphite furnace atomic absorption spectrometry and thermal ionization mass spectrometry. Based on stable lead isotopes and retrospective isentropic air mass analyses, four air mass sources were evidenced including (1) temperate U.S. and (2) boreal Canadian westerlies, and (3) boreal and northern Europe easterlies associated with (4) Mediterranean and Saharan easterlies. Lead isotopic signatures clearly distinguished emission source regions over the North Atlantic with 206Pb/207Pb ratios of 1.19–1.22 for North American westerlies, 1.10–1.12 for European boreal easterlies, and 1.15–1.16 for Saharan trade easterlies. Also, the contrasting ratios between precipitation and aerosol demonstrate a vertical mixing of chemical sources in precipitation from contrasting air masses of different origin. The air mass trajectories were independently calculated and are in general agreement with the lead isotopic tracers. The isotopic tracers allowed more confident conclusions on air mass sources, particularly after a few days of oceanic transport. Also, the trajectories appeared to be very useful in explaining the strong variability of the trace metal concentrations during restricted periods of sampling time aboard a moving ship. To a lesser extent, the atmospheric emission sources were characterized by trace element concentrations. The occurrence of large dust loadings in the Saharan trade easterlies contributed abundant crustal elements and were also associated with enriched anthropogenic elements from southern Europe. Scavenging ratios were calculated for lead and cadmium during select periods when aerosol and precipitation were collected under the same meteorological regimes. The cadmium ratio is much greater than that of lead, indicating that cadmium and lead are each transported or scavenged on distinct populations of aerosols. For lead, the ratio is less in the North Atlantic than in the Pacific, suggesting an aerosol concentration dependence. Like the Pacific, the ratios increase for the lead, dust, and sea salt. One may thus conclude that marine scavenging ratios cannot yet be used effectively until factors such as concentration dependency and local conditions of tropospheric processing are better defined.

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Tài liệu tham khảo

10.1029/JD090iD01p02391

10.1029/JD093iD04p03773

Biscaye P. E., 1974, Rb/Sr, Sr‐87/Sr‐86 isotope system as an index of the provenance of continental dust in the open Atlantic Ocean, J. Atmos. Res., 8, 819

10.1007/978-94-009-7169-1_7

10.1016/0012-821X(79)90049-9

Buat‐Ménard P., 1987, Lead, Mercury, Cadmium and Arsenic in the Environment, 147

Chow T. J. C. B.Snyder J. L.Earl Isotope ratios of lead as pollutant source indicators Proceedings IAEA‐SM‐191/4 95–108Int. Atom. Energy Comm. Vienna Austria 1975.

10.1016/0004-6981(84)90330-5

10.1029/89JD01595

Duce R. A., 1976, Marine Pollutant Transfer, 77

10.1029/JD092iD07p08437

10.1038/308409a0

Englemann R. J., 1970, Precipitation Scavenging, 475

Facchetti S. F.Geiss P.Gaglione A.Colombo G.Garibaldi G.Spallanzani G.Gili Isotopic lead experiment status report Comm. Eur. Communities Rep.JRC EUR 3852 EN 112 1982.

Flament P. Les métaux traces associés aux aérosols atmosphériques: Apports au milieu marin du littoral Nord‐Pas de Calais Ph.D. thesis p.175 Univ. des Sci. et Tech. de Lille France 1985.

10.1038/339455a0

10.1029/GB001i004p00261

Galloway J. N., 1986, Chemistry of Acid Rain, 39

Griffin J. J., 1963, The Sea, 728

10.1029/JC094iC11p16243

Hopper J. F., 1990, Regional source discrimination of atmospheric aerosols in Europe using the isotopic composition of lead, Tellus

10.1029/GB001i002p00117

Junge C. E., 1977, Adv. in Environ. Sci. and Technol., 7

10.1126/science.231.4742.1131

10.1016/0016-7037(88)90054-3

10.1016/0016-7037(79)90162-5

Maring H., 1989, Chemical Oceanography, 83

10.1038/330154a0

10.1029/JD094iD06p08584

10.1029/JC079i033p05019

10.1029/JD092iD11p13289

10.1038/333134a0

Pacyna J. M. Trace element emission from anthropogenic sources in Europe Tech. Rep. NILU 10/82ref. 24781 107Norw. Inst. for Air Res. Lillestrom 1983.

Patterson C. C., 1976, Accuracy in Trace Analysis: Sampling, Sample Handling, Analysis, Spec. Publ., 321

10.1016/0016-7037(87)90078-0

10.1016/0304-4203(87)90005-3

10.1016/0004-6981(84)90150-1

10.1029/JD095iD04p03687

Scott B. C., 1981, Atmospheric Pollutants in Natural Waters, 3

10.1016/0004-6981(88)90042-X

10.1029/JC087iC11p08857

10.1016/0012-821X(87)90203-2

10.1029/JC093iC12p15715

10.1016/0016-7037(80)90127-1

10.1007/978-94-009-7169-1_6

10.1126/science.211.4489.1424

10.1029/GB004i002p00133

10.1038/329144a0

10.1016/0004-6981(89)90049-8

10.1016/0004-6981(89)90263-1

Tatsumoto M., 1963, Earth Science and Meteoritics, 74

10.1021/es00162a003

10.1016/0004-6981(87)90193-4

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Global Biogeochemical Cycles

Tập 4 Số 4

431-443

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