Potential influence of rapid climate change on elemental geochemistry distributions in lacustrine sediments-A case study at a high Arctic site in Ny-Ålesund, Svalbard.

Metal contamination has become an increasingly severe environmental issue due to intense anthropogenic activities in recent decades. Many studies have reported a rapidly increasing trend of heavy metal contents in sedimentary records. In this study, two lacustrine sediment cores (LDL and YL) far away from scientific research stations were collected in Ny-Ålesund and analyzed for the vertical distributions of 17 elemental concentrations (Cu, Zn, Pb, Co, Ni, Cr, Sr, Ba, Mn, P, Ti, K2O, Na2O, CaO, MgO, Fe2O3, Al2O3), CIA and TOC contents. The results indicated that only the proxies Pb, P, CaO, TOC, and CIA showed an increasing trend in the upper 7 cm section of the sediment cores, while most of the elements' concentrations decreased towards the surface. The rapid increase of TOC contents is likely related to the climate warming over the past 200 years, which promotes the prosperity of vegetation and thus leads to more input of organic matter into the lakes. Moreover, a large number of seabirds live around the sampling position and the seabird guano contains high concentrations of P, which could be regarded as an important nutrient source for vegetation. Additionally, the rapid climate warming could accelerate the chemical weathering rates, and thus lead to increased CaO contents in the sediment profiles according to its geological background. Therefore, the concentrations of other elements are very likely diluted by the high contents of organic matter and CaO in the upper part of the sediment cores. It is noteworthy that the rapidly increasing trend of Pb contents are related to the gas-oil powered generators in Ny-Ålesund and long-range atmospheric transport from Europe. This study highlighted the nonnegligible influence of climate warming on the inorganic elemental geochemistry distributions in remote lakes.