BIO-GEO-CLIM Laboratory, Tomsk State University, 36 av. Lenina, 634050 Tomsk, Russia.
BIO-GEO-CLIM Laboratory, Tomsk State University, 36 av. Lenina, 634050 Tomsk, Russia; Federal Center for Integrated Arctic Research, Institute of Ecological Problem of the North, 23 Nab. Severnoi Dviny, 163000 Arkhangelsk, Russia; GET UMR 5563 CNRS University of Toulouse, 14 av. Edouard Belin, 31400 Toulouse, France.
Sci Total Environ. 2021 Apr 1;763:144201. doi: 10.1016/j.scitotenv.2020.144201. Epub 2020 Dec 25.
The chemical composition of thermokarst lake ecosystem components is a crucial indicator of current climate change and permafrost thaw. Despite high importance of macrophytes in shallow permafrost thaw lakes for control of major and trace nutrients in lake water, the trace element (TE) partitioning between macrophytes and lake water and sediments in the permafrost regions remains virtually unknown. Here we sampled dominant macrophytes in thermokarst lakes of discontinuous and continuous permafrost zones in the Western Siberia Lowland (WSL) and measured major and trace elements in plant biomass, lake water, lake sediments and sediment porewater. All six plant species (Hippuris vulgaris L., Glyceria maxima (Hartm.) Holmb., Comarum palustre L., Ranunculus spitzbergensis Hadac, Carex aquatilis Wahlenb s. str., Menyanthes trifoliata L.) sizably accumulated macronutrients (Na, Mg, Ca), micronutrients (B, Mo, Nu, Cu, Zn, Co) and toxicants (As, Cd). Accumulation of other trace elements, including rare earth elements (REE), in macrophytes relative to pore waters and sediments was highly variable among species. Using miltiparametric statistics, we described the behavior of ТЕ across two permafrost zones and identified several group of elements depending on their sources in the lake ecosystems and their affinity to sediments and macrophytes. Under future climate warming and shifting the permafrost border to the north, we anticipate an increasing uptake of heavy metals and lithogenic low mobile elements such as Ti, Al, Cr, As, Cu, Fe, Ni, Ga, Zr, and REEs by macrophytes in the discontinuous permafrost zone and Ba, Zn, Pb and Cd in the continuous permafrost zone. This may eventually diminish transport of metal micronutrients and geochemical tracers from soils to lakes and rivers and further to the Arctic Ocean.
多年冻土区热喀斯特湖生态系统组分的化学成分是当前气候变化和多年冻土融化的关键指标。尽管大型植物在浅层多年冻土融化湖中对控制湖水中的主要和痕量养分具有重要作用，但多年冻土区大型植物与湖水和沉积物之间痕量元素（TE）的分配情况仍几乎未知。本研究在西西伯利亚低地（WSL）的不连续和连续多年冻土区的热喀斯特湖中采样了优势大型植物，并测量了植物生物量、湖水、湖底沉积物和底泥孔隙水中的主要和痕量元素。所有 6 种植物（黄花狸藻、宽叶泽苔草、毛茛、北极狐尾藻、漂筏薹草、三叶委陵菜）大量积累了大量营养元素（Na、Mg、Ca）、微量营养元素（B、Mo、Nu、Cu、Zn、Co）和有毒元素（As、Cd）。与孔隙水和沉积物相比，大型植物对其他痕量元素（包括稀土元素）的积累在物种间差异很大。利用多参数统计学，我们描述了 TE 在两个多年冻土区的行为，并根据其在湖泊生态系统中的来源以及与沉积物和大型植物的亲和力，确定了几组元素。在未来气候变暖以及多年冻土边界向北移动的情况下，我们预计不连续多年冻土区的大型植物对重金属和岩石成因低迁移元素（如 Ti、Al、Cr、As、Cu、Fe、Ni、Ga、Zr 和 REE）的吸收会增加，而连续多年冻土区的大型植物对 Ba、Zn、Pb 和 Cd 的吸收会增加。这可能最终会减少从土壤到湖泊和河流再到北冰洋的金属微量元素和地球化学示踪剂的输送。
