Tracing anthropogenic aerosol trace metal sources in the North Atlantic Ocean using Pb, Zn and Ni isotopes - Université de Bretagne Occidentale Access content directly
Journal Articles Marine Chemistry Year : 2024

Tracing anthropogenic aerosol trace metal sources in the North Atlantic Ocean using Pb, Zn and Ni isotopes


Atmospheric deposition of trace metals of natural or anthropogenic origin is an important input of micronutrients to the surface ocean. However, understanding its direct impact on oceanic element cycles is challenging due to scarce data, coupled to diverse aerosol sources and variable solubilities. Here, we present a dataset that combines Ni, Zn and Pb isotopes for samples from the Moroccan and Senegalese coasts and in the high latitude North Atlantic Ocean. We combine the new with published data for other circum-North Atlantic sources to assess the processes that determine the isotope signatures in different types of aerosols. We then use open marine aerosol data to investigate the impact of these signatures in the open ocean. Isotope analyses were conducted on bulk aerosols (TSP), on their ultra-high-purity water leachates, and on rainwaters. Aerosols characterized by crustal elemental abundances have isotope compositions similar to Saharan mineral dust. Mixing with anthropogenic aerosols from Europe/North Africa results in lower Pb-206/Pb-207 and Pb-208/Pb-207 values for the Eastern North Atlantic region. Higher Pb-206/Pb-207 at a given Pb-208/Pb-207, observed near the Canadian margin and occasionally at the Senegalese coast, points to anthropogenic inputs from North America. Based on trends in the aerosol data (e.g., delta Zn-66(JMC-Lyon) versus Pb-206/Pb-207, delta Ni-60(SRM986) versus Ni/V), we identify several anthropogenic sources of Zn and Ni. The delta Zn-66(JMC-Lyon) of low-temperature pollution (e.g., non-exhaust traffic emission) appears to be around -0.1 parts per thousand to 0.2 parts per thousand, while leachate delta Zn-66(JMC-Lyon) as low as -0.21 parts per thousand indicates contributions from high-temperature combustion or smelting processes. Among aerosols with good correlations between Ni and V, delta Ni-60(SRM986) > 0.40 parts per thousand traces Ni contributions from oil combustion. Other Ni-enriched sources, possibly originating from laterite or sulfide, show relatively low delta Ni-60(SRM986) (as low as -0.85 parts per thousand) and low V/Ni. Generally, aerosol sources for Zn are consistent throughout the North Atlantic, while Ni can be highly heterogenous. Combining the new data with literature elemental data, ratios of soluble Zn/Pb in anthropogenic aerosols are 1-100 times surface ocean ratios, suggesting that the low delta Zn-66(JMC-Lyon) observed in anthropogenic aerosol can be key in controlling the upper ocean Zn isotope composition. These aerosols have, however, much less significance for surface ocean Ni
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Dates and versions

hal-04417031 , version 1 (25-01-2024)



Xingchao Zhang, Nolwenn Lemaitre, Jörg Dominik Rickli, Tim Jesper Suhrhoff, Rachel Shelley, et al.. Tracing anthropogenic aerosol trace metal sources in the North Atlantic Ocean using Pb, Zn and Ni isotopes. Marine Chemistry, 2024, 258, pp.104347. ⟨10.1016/j.marchem.2023.104347⟩. ⟨hal-04417031⟩
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