Although subglacial aquatic environments are widespread beneath the Antarctic ice sheet, subglacial biogeochemistry is not well understood, and the contribution of subglacial water to coastal ocean carbon and nutrient cycling remains poorly constrained. The Whillans Subglacial Lake (SLW) ecosystem is upstream from West Antarctica's Gould‐Siple Coast ~800 m beneath the surface of the Whillans Ice Stream. SLW hosts an active microbial ecosystem and is part of an active hydrological system that drains into the marine cavity beneath the adjacent Ross Ice Shelf. Here we examine sources and sinks for organic matter in the lake and estimate the freshwater carbon and nutrient delivery from discharges into the coastal embayment. Fluorescence‐based characterization of dissolved organic matter revealed microbially driven differences between sediment pore waters and lake water, with an increasing contribution from relict humic‐like dissolved organic matter with sediment depth. Mass balance calculations indicated that the pool of dissolved organic carbon in the SLW water column could be produced in 4.8 to 11.9 yr, which is a time frame similar to that of the lakes’ fill‐drain cycle. Based on these estimates, subglacial lake water discharged at the Siple Coast could supply an average of 5,400% more than the heterotrophic carbon demand within Siple Coast embayments (6.5% for the entire Ross Ice Shelf cavity). Our results suggest that subglacial discharge represents a heretofore unappreciated source of microbially processed dissolved organic carbon and other nutrients to the Southern Ocean.

中文翻译：

---

南极西部冰盖下方淡水生态系统与冰海海洋环境之间的生物地球化学连通性

尽管在南极冰盖下广泛存在冰下水生环境，但对冰下生物地球化学的认识还不充分，冰下水对沿海海洋碳和养分循环的贡献仍然受到限制。Whillans次冰川湖（SLW）生态系统位于西南极洲Gould-Siple海岸上游〜Whillans冰流表面以下约800 m。SLW拥有活跃的微生物生态系统，并且是活跃的水文系统的一部分，该系统排入相邻的罗斯冰架下方的海腔。在这里，我们检查了湖泊中有机物的来源和汇，并估计了从排放物到沿海隔离带的淡水碳和养分输送。基于溶解性有机物的荧光表征揭示了微生物驱动的沉积物孔隙水和湖水之间的差异，随着腐殖质类腐殖质的溶解性有机物随着沉积物深度的增加而增加。质量平衡计算表明，SLW水柱中的溶解有机碳库可能在4.8至11.9年内产生，这是一个与湖泊补给-排水周期相似的时间范围。根据这些估计，在Siple海岸排放的冰河湖底水比Siple海岸隔离带的异养碳需求（整个Ross冰架腔的6.5％）平均多提供5,400％。