Grider A, Saros J, Northington R, Yde JC. Glacially-fed lakes of West Greenland have elevated metal and nutrient concentrations and serve as regional repositories of these materials.
THE SCIENCE OF THE TOTAL ENVIRONMENT 2025;
967:178744. [PMID:
39946888 DOI:
10.1016/j.scitotenv.2025.178744]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2024] [Revised: 10/18/2024] [Accepted: 02/03/2025] [Indexed: 03/05/2025]
Abstract
The fate of heavy metals and nutrients melting out of the cryosphere into aquatic systems is not well understood. To address this, we measured heavy metals and nutrients in the water and sediment of four glacially-fed (GF) and four snow and groundwater-fed (SF) lakes near Kangerlussuaq, West Greenland during the summer of 2023. Average nutrient concentrations - total phosphorus (TP), NO3-, and NH4+ - in the water of GF lakes were 86 % higher and average total concentrations of some metals - Cd, Pb, Cr, Co, Ni, Al, Fe, Cu, Zn - were 137 % higher compared to nearby SF lakes. This pattern was also reflected in the sediment, where metal concentrations were generally higher in GF lakes compared to SF lakes. However, a few metals, including Hg, As, Cu, and Pb, were higher in SF compared to GF sediment. Our results suggest metals may be increasing over the past few years to decades in GF lakes, and certain metals have increased in SF lakes, notably Hg has substantially increased (298 %), as well as Pb (52.8 %), in SF lakes over the past century. The increase in Hg and Pb in SF, but not GF lakes, is likely due to the higher organic carbon and longer residence times of SF compared to GF lakes. In one GF lake, we quantified inputs and outputs of metals and nutrients, and we found that loads declined by an average of 71 % for metals and 68 % for nutrients from the lake inlet to outlet, suggesting the lake is a sink for these materials. SF lakes also appear to be reservoirs of some metals, specifically atmospherically deposited metals (Hg, Pb, As, and Cu). Our results highlight that GF lakes in West Greenland are elevated in nutrients and some metals compared to nearby SF lakes, indicating that the source of these materials is likely meltwater from the glacial system. We found that GF lakes can sequester a high percentage of the nutrients and metals flowing into them; however, as meltwater fluxes increase due to climate change, the ability of these lakes to remain sinks is an open question.
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