Anthropogenic lead pervasive in Canadian Arctic seawater

Abstract

Anthropogenic Pb is widespread in the environment including remote places. However, its presence in Canadian Arctic seawater is thought to be negligible based on low dissolved Pb (dPb) concentrations and proxy data. Here, we measured dPb isotopes in Arctic seawater with very low dPb concentrations (average ∼5 pmol ⋅ kg−1) and show that anthropogenic Pb is pervasive and often dominant in the western Arctic Ocean. Pb isotopes further reveal that historic aerosol Pb from Europe and Russia (Eurasia) deposited to the Arctic during the 20th century, and subsequently remobilized, is a significant source of dPb, particularly in water layers with relatively higher dPb concentrations (up to 16 pmol ⋅ kg−1). The 20th century Eurasian Pb is present predominantly in the upper 1,000 m near the shelf but is also detected in older deep water (2,000 to 2,500 m). These findings highlight the importance of the remobilization of anthropogenic Pb associated with previously deposited aerosols, especially those that were emitted during the peak of Pb emissions in the 20th century. This remobilization might be further enhanced because of accelerated melting of permafrost and ice along with increased coastal erosion in the Arctic. Additionally, the detection of 20th century Eurasian Pb in deep water helps constrain ventilation ages. Overall, this study shows that Pb isotopes in Arctic seawater are useful as a gauge of changing particulate and contaminant sources, such as those resulting from increased remobilization (e.g., coastal erosion) and potentially also those associated with increased human activities (e.g., mining and shipping).

Amount, Sources, and Dissolution of Aerosol Trace Elements in the Canadian Arctic

“…Hence, it is possible that some previously deposited aerosols from these high 20th century emission sources were remobilized as dust in the summer. This would be consistent with the recent Arctic study 85 that observed remobilization of European and Russian Pb with low 206 Pb/ 207 Pb (<1.15), which was deposited to the Arctic region during the peak of Pb emissions in the 20th century, into Arctic seawater near shelves. This source may continue to be an important source of remobilized Pb to the region from melting permafrost 86 and ice sheets 87 and increases in coastal erosion.…”

Quantifying Ice‐Sheet Derived Lead (Pb) Fluxes to the Ocean; A Case Study at Nioghalvfjerdsbræ

“…Whilst Pb distributions across the North Atlantic (Bacon et al., 1988; Rusiecka et al., 2018) and North Pacific (Chien et al., 2017; Sañudo‐Wilhelmy & Flegal, 1994) are now well described, comparatively little is known about the biogeochemical cycling of Pb in the Arctic (Colombo, Rogalla, et al., 2019; de Vera et al., 2021) and high latitude (>65°N) North Atlantic shelf seas (Schlosser & Garbe‐Schönberg, 2019). Rivers draining into the Arctic Ocean deliver large quantities of mostly natural Pb to shelf regions (Colombo, Brown, et al., 2019; Guay et al., 2010; Guieu et al., 1996).…”

Snow contamination by heavy metals and metalloids in a polar town (a case study of Nadym, Russia)

“…Pb deposited in the Arctic originated from coal, gasoline, and wood combustion, smelter operations, and other industrial processes (McConnell et al 2002;Colombo et al 2019;De Vera et al 2021). Non-ferrous metallurgy enterprises located in southern Siberia and northern Kazakhstan are another large source of Pb deposited in Western Siberia (Talovskaya 2022).…”