Continental origin and industrial sources of trace metals in the Northwest Atlantic troposphere

Trace metals (Mn, Fe, Ni, Cu, Zn, Cd, Pb and stable lead isotopes) have been analyzed in precipitation and total aerosols collected in the northwest Atlantic troposphere in April and November 1989. According to stable lead isotope signatures we encountered two main air mass sources, Mediterranean easterlies (206Pb/207Pb=1.131) and US westerlies (206Pb/207Pb=1.195–1.205). The phasing out of leaded gasoline has been invoked to explain the decrease of the 206Pb/207Pb ratios from 1.22 to 1.20 for the past 10 years in North America. Based on trajectory analyses, intermediate 206Pb/207Pb ratios are explained by a mixing of pure US westerlies with Canadian air masses (206Pb/207Pb=1.190–1.195) or Mediterranean air masses (206Pb/207Pb=1.18–1.19). Isentropic trajectories are very useful in explaining the variability of trace metal concentrations, a result of the fluctuating transport range of anthropogenic aerosols to remote marine areas of the North Atlantic. Lead concentrations appear to be closely correlated to the air mass transport patterns as defined from the meteorological analyses. For instance oceanic air masses transported over remote marine areas for more than three days were characterized by lead concentrations 2 to 10 times lower (Pb=0.5 to 2 ng/scm) than coastal air masses (Pb=3 to 10 ng/scm).Anthropogenic trace metal concentrations are generally in good agreement with the air mass signatures which display Pb and Cu, Ni, Zn concentrations higher than 2 and 10 ng/scm respectively in aerosol samples for the US source. Trace metal elemental ratios and soil enrichment factors were used to define industrial sources. Aerosol originating from the US exhibits the distinct industrial signature of Cu/Ni production and coal-oil combustion, while steel metallurgy could account for more than 50% of the overall Mn input into the Northwest Atlantic ocean.

[1]  W. Sturges,et al.  Stable lead isotope ratios in arctic aerosols: evidence for the origin of arctic air pollution , 1989 .

[2]  R. Artz,et al.  Summary of meteorological conditions over the North Atlantic Ocean during GCE/CASE/WATOX , 1990 .

[3]  W. Sturges,et al.  The use of stable lead 206/207 isotope ratios and elemental composition to discriminate the origins of lead in aerosols at a rural site in eastern Canada , 1989 .

[4]  F. Dulac,et al.  Stable lead isotope tracers of air mass trajectories in the Mediterranean region , 1987, Nature.

[5]  R. Duce,et al.  Atmospheric trace elements at Enewetak Atoll: 2. Transport to the ocean by wet and dry deposition , 1985 .

[6]  R. Duce,et al.  Dry deposition models and the air/sea exchange of trace elements , 1986 .

[7]  T. Church,et al.  A method for the collection, handling, and analysis of trace metals in precipitation. , 1987, Environmental science & technology.

[8]  E. Boyle,et al.  LEAD IN CORALS: RECONSTRUCTION OF HISTORICAL INDUSTRIAL FLUXES TO THE SURFACE OCEAN , 1987 .

[9]  C. Patterson,et al.  Magnitudes and sources of precipitation and dry deposition fluxes of indestrial and natural leads to the North Pacific at Enewetak , 1982 .

[10]  Francis E. Grousset,et al.  Neodymium isotopes as tracers in marine sediments and aerosols: North Atlantic , 1988 .

[11]  E. Goldberg.  Rock volatility and aerosol composition , 1976, Nature.

[12]  B. Hamelin,et al.  Pb isotopes in surficial pelagic sediments from the North Atlantic , 1990 .

[13]  C. Lambert,et al.  Evidence of recent lead pollution in deep north-east Atlantic sediments , 1987, Nature.

[14]  T. J. Chow,et al.  Isotope ratios of lead as pollutant source indicators , 1975 .

[15]  W. Slinn.  Air-to-Sea Transfer of Particles , 1983 .

[16]  Robert A. Duce,et al.  Marine pollutant transfer , 1976 .

[17]  W. Sturges,et al.  Regional source discrimination of atmospheric aerosols in Europe using the isotopic composition of lead , 1991 .

[18]  J. Prospero,et al.  Lead isotopes in trade wind aerosols at Barbados: the influence of European emissions over the North Atlantic , 1989 .

[19]  P. Buat-Ménard,et al.  Variable influence of the atmospheric flux on the trace metal chemistry of oceanic suspended matter , 1979 .

[20]  J. Nriagu,et al.  Quantitative assessment of worldwide contamination of air, water and soils by trace metals , 1988, Nature.

[21]  P. Liss,et al.  Air-Sea Exchange of Gases and Particles , 1983 .

[22]  J. Nriagu,et al.  Isotopic tracers of lead contamination in the Great Lakes , 1989, Nature.

[23]  E. Boyle,et al.  Thermocline ventilation of anthropogenic lead in the western North Atlantic , 1988 .

[24]  J. Barber,et al.  Release of Particles Containing Metals from Vegetation into the Atmosphere , 1977, Science.

[25]  L. Lamberts,et al.  Stable lead isotopes in pond sediments as tracer of past and present atmospheric lead pollution in Belgium , 1984 .

[26]  J. L. Fasching,et al.  Estimates of the transport of trace metals from the ocean to the atmosphere , 1984 .

[27]  F. Mackenzie,et al.  Atmospheric trace metals: global cycles and assessment of man's impact , 1979 .

[28]  A. Vinogradov.  The geochemistry of rare and dispersed chemical elements in soils , 1959 .

[29]  J. Prospero,et al.  Dust Concentration in the Atmosphere of the Equatorial North Atlantic: Possible Relationship to the Sahelian Drought , 1977, Science.

[30]  F. Elbaz-Poulichet,et al.  Stable lead isotopes ratios in major french rivers and estuaries , 1986 .

[31]  C. Patterson,et al.  Review of data on eolian fluxes of industrial and natural lead to the lands and seas in remote regions on a global scale , 1987 .

[32]  T. Jickells,et al.  A comparison of atmospheric inputs and deep-ocean particle fluxes for the Sargasso Sea , 1987 .

[33]  C. Patterson,et al.  Lead concentrations in the northeast Pacific: evidence for global anthropogenic perturbations , 1981 .

[34]  W. Sturges,et al.  Lead 206/207 isotope ratios in the atmosphere of North America as tracers of US and Canadian emissions , 1987, Nature.

[35]  Y. Erel,et al.  Trace elements in the North Atlantic troposphere: Shipboard results of precipitation and aerosols , 1990 .

[36]  J. Galloway,et al.  Watox-86 overview and western North Atlantic Ocean S and N atmospheric budgets , 1987 .

[37]  A. Knap,et al.  Atmospheric and precipitation chemistry over the North Atlantic Ocean: Shipboard results, April–May 1984 , 1991 .

[38]  A. Knap,et al.  THE WET DEPOSITION OF TRACE METALS TO THE WESTERN ATLANTIC OCEAN AT THE MID-ATLANTIC COAST AND ON BERMUDA , 1984 .

[39]  D. Blanchard,et al.  The Production, Distribution, and Bacterial Enrichment of the Sea-Salt Aerosol , 1983 .

[40]  C. Patterson,et al.  Magnitude of lead flux to the atmosphere from volcanoes , 1987 .

[41]  R. Duce,et al.  Atmospheric Trace Metals at Remote Northern and Southern Hemisphere Sites: Pollution or Natural? , 1975, Science.

[42]  Rainer Bleck,et al.  Meteorological analysis of long range transport of mineral aerosols over the North Pacific , 1989 .

[43]  J. Galloway,et al.  The transatlantic transport of sulfur , 1988 .

[44]  A. Knap,et al.  Trace metals in Bermuda rainwater , 1984 .

[45]  M. Joseph.  Eolian transport to the world ocean , 1981 .