The Arctic Ocean is a net sink for anthropogenic lead deposited into the Atlantic Ocean

Article https://doi.org/10.1038/s41467-025-67620-9 The Arctic Ocean is a net sink for anthropogenic lead deposited into the Atlantic Ocean Received: 22 May 2025 Check for updates 1234567890():,; 1234567890():,; Accepted: 3 December 2025 Stephan Krisch Birgit Rogalla 1,2 7,8 , Arianna Olivelli3,4,9, Loes J. A. Gerringa5, Rob Middag & Eric P. Achterberg 2 5,6 , Humans emitted millions of tons of the toxic element lead (Pb) into the atmosphere. The North Atlantic Ocean has been strongly affected by atmospheric Pb deposition, however the role of ocean currents in dispersing the Atlantic dissolved Pb (dPb) burden remains unclear. Here, we show that the Arctic Ocean received a dPb flux of 611 ± 74 Mg·a-1 from the North Atlantic Ocean in 2015/2016, making the Arctic Ocean a previously unrecognized net sink of Atlantic dPb (378 ± 85 Mg·a-1). This input is comparable to Arctic riverine dPb discharge (344 ± 222 Mg·a-1). Lead isotope measurements trace the origin of dPb in the Arctic Ocean back to anthropogenic emissions from North America and Eurasia. Elevated dPb concentrations in the North Atlantic Ocean prior to the global-phase out of leaded gasoline (1986-2021) suggests ~5-fold higher fluxes from the North Atlantic in the late 1980s relative to 2015/2016, explaining the widespread contamination of Arctic abyssal sediments with Pb. Lead (Pb) is a toxic element, and uptake by marine biota and incorporation into the food chain1,2 form a pathway of exposure to humans3,4. The natural geochemical cycles of Pb in the ocean have been markedly perturbed by anthropogenic emissions5,6. Hundredthousands of tons of Pb have been emitted into the atmosphere since the Phoenician and Roman times, particularly as a result of industrialisation, by melting of ores, combustion of coal, and the use of leaded gasoline7,8, and resulted in large-scale deposition of Pb into the surface ocean6. The North Atlantic is among the regions most affected by atmospheric Pb deposition due to extensive use of Pb in North America and Europe6,9. With the emerging awareness of adverse health effects associated with exposure to Pb10,11, the global phase-out of leaded gasoline between 1986 and 2021, and reductions in industrial emissions of Pb12,13 resulted in a decrease in dissolved Pb (dPb) concentrations in surface waters of the North Atlantic Ocean9,14. However, current surface dPb concentrations in the Atlantic Ocean of ~20–40 pmol L−1 (pM)15,16 remain above pre-industrial levels ( ~ 15 pM for surface waters in the North Atlantic Ocean before the 1850s as per ref. 14), indicating that the Pb emissions are yet to return to preindustrial levels. The marine biogeochemical cycle of Pb in the Arctic and Atlantic Oceans is governed by its high particle reactivity16,17. The tendency for Pb to absorb onto particle surfaces18,19, particularly organic debris20,21, results in short residence times of <1 year in particle-rich surface waters22,23 and swift export to depth17,24. Residence times of dPb in intermediate and deep Atlantic waters are considerably longer ( ~ 20 years in the Eastern Arctic Ocean25), suggesting the possibility for longrange transport of North Atlantic Pb to the adjacent Arctic Ocean as part of the thermohaline circulation. Abyssal sediments in the Central Arctic show contamination with concentrations exceeding 30 mg kg−1 as a result of atmospheric deposition and advection of Atlantic Water through the Fram Strait and across the Barents Sea26,27. This represents a ~3-fold enrichment compared to Pb concentrations of more pristine sediments, for example, near Novaya Zemlya ( ~ 10 mg kg−127). More 1 Technical University of Braunschweig, Braunschweig, Germany. 2GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. 3Department of Earth Science & Engineering, Imperial College London, London, UK. 4Grantham Institute for Climate Change and the Environment, Imperial College London, London, UK. 5NIOZ Royal Netherlands Institute for Sea Research, Den Burg, The Netherlands. 6Centre for Isotope Research, University of Groningen, Groningen, The Netherlands. 7Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada. 8British e-mail: Antarctic Survey, Cambridge, UK. 9Present address: Flanders Marine Institute (VLIZ), Ostend, Belgium. Nature Communications | (2025)16:11238 1 Article https://doi.org/10.1038/s41467-025-67620-9 explicitly, surface sediments underlying Atlantic Water in the Eastern and Central Arctic Ocean are ~2–3-fold enriched above pre-industrial levels28. This indicates that atmospheric Pb deposition into the North Atlantic Ocean and subsequent advection of Atlantic Water across the Arctic-Atlantic gateways have been a prominent supply of dPb to the Arctic Ocean in the past. The first observations of dPb in surface (<15 m) waters of the Fram Strait and the Barents Sea Opening in 2012 indicated ongoing Pb transport from anthropogenic sources with Atlantic Water into the Arctic Ocean29. The lack of sub-surface data has so far precluded the assessment of subsurface contributions to ArcticAtlantic dPb exchange and how water mass transport influences dPb concentrations in the Central Arctic Ocean. In this study, we investigate the processes controlling the dPb distribution in the Arctic-Atlantic gateways based on full water column surveys in the Fram Strait (GN05, 21 July–1 September 2016), Barents Sea Opening (GN04, 6–9 October 2015) and Canadian Arctic Archipelago (GN02/GN03, 10 August–24 September 2015). We present flux calculations concerning the import and export of dPb at the ArcticAtlantic gateways. Combined, our results show that the Arctic Ocean is a net sink for anthropogenic Pb derived from the Atlantic. Our research establishes a baseline for future investigations concerning changes in Arctic-Atlantic dPb fluxes. Results and discussion Dissolved Pb distributions The study region was sampled over the full water column for dPb at 44 stations (Fig. 1), targeting Arctic-Atlantic exchange of water masses: 27 stations across the Fram Strait (Supplementary Fig. 1), 7 stations across the Barents Sea Opening (Supplementary Fig. 1), and 10 stations along the Parry Channel in the Canadian Arctic Archipelago (Supplementary Fig. 2). Sampling and analyses for dPb were conducted using trace element clean methods and followed GEOTRACES protocols30 (see “Method” section for details on sampling and analyses). Water mass definitions follow Rudels et al.31. Dissolved Pb concentrations in surface water of the Fram Strait showed an west-to-east gradient with increasing concentrations from the Greenlandic coast (4.5 ± 2.0 pM for <50 m depth at stations 20–23, n = 31) towards Svalbard (17.9 ± 2.1 pM for <50 m depth at stations 1–2, n = 6) (Fig. 2 and Supplementary Fig. 3) indicating increasing anthropogenic impacts towards the eastern Fram Strait, in agreement with observations in 201229. A subsurface maximum in the Atlantic Water of the (...truncated)