From ice to ocean: Understanding the impacts of melting glaciers on marine biogeochemical cycles

气候变化是我们这个时代的决定性挑战，它从根本上重组了地球的生态系统及其所支持的人类社会。这一点在加拿大的北极地区表现得最为明显，那里的冰川正在融化。虽然这些萎缩的冰块对海平面上升的贡献是无可争议的，但它们在更广泛的生物地球化学循环中的作用才刚刚开始被揭示出来。当冰川融化时，它们向海洋贡献了大量的水、冰、沉积物和溶解的化学物质。最近在格陵兰岛和南极洲周围开展的工作表明，与冰川有关的营养物质和碳有可能刺激海洋食物网底部的生产，并对食物链上游产生相关影响（例如，提高当地鱼类收成），并通过更活跃的海洋生物泵对更广泛的碳循环产生影响。然而，关于冰川系统输出了哪些生命必需元素，这些排放到海洋中会发生什么，以及对海洋微生物群落的影响，知识差距仍然存在。没有什么地方比加拿大北极群岛（CAA）更突出这些知识上的空白了——在这个地区，冰川融水在海洋生物地球化学循环中的作用在很大程度上没有被探索过——尽管事实上，CAA是冰川退缩和融水流入海洋的热点。在接下来的5年里，我和我的团队将努力量化冰川系统中营养物质和碳的当代输出，以及这种输出对海洋过程和生态系统的相关影响。具体来说，我们会问：1)离开冰系统的生物地球化学成分（营养物质、碳）的来源是什么？2)沿海海洋中冰川融水及其相关成分的命运如何？3)冰川融水如何影响海洋微生物群落的生产、结构和功能？为了回答这些问题，我们将进行新的冰到海洋的研究，将化学物种的实地测量与分子生物学分析和实验室实验相结合。这种方法将在更广泛的区域尺度上解决冰川末端附近融水相互作用的影响，并针对尚未解决的机制问题。我的计划将通过HQP使用跨学科技术，连接海洋学，地球化学和微生物生态学来实现。我们将一起在CAA的琼斯湾开展这项工作，这是一个被冰川包围的地区，也是因纽特人格里斯峡湾村庄的所在地。这里的潮汐冰川的末端是高产的水域，是小村庄的狩猎场。了解食物网底部海洋生产的驱动因素，以及这些驱动因素对气候变化的敏感性，对这个北部社区的长期健康和北冰洋沿海的功能都很重要。总的来说，这项研究是揭示过去、现在和未来冰川融化对海洋碳循环作用的关键一步。

Climate change is the defining challenge of our times, fundamentally reorganizing our planet's ecosystems and the human societies they support. Nowhere is this more evident than in Canada's Arctic, where melting glaciers define the landscape. While the contributions of these shrinking ice masses to sea level rise are undisputed, their role in broader biogeochemical cycling is just beginning to be revealed. When glaciers melt, they contribute large quantities of water, ice, sediments, and dissolved chemicals to the ocean. Recent work around Greenland and Antarctica shows that glacially-associated nutrients and carbon have the potential to stimulate production at the base of marine food webs with associated impacts up the food chain (e.g., enhanced local fish harvests) and on the broader carbon cycle via a more active marine biological pump. Yet, knowledge gaps remain about what life-essential elements are exported from glacial systems, what happens to this discharge in the ocean, and what the impacts are on marine microbial communities. Nowhere are these gaps in knowledge more prominent than in the Canadian Arctic Archipelago (CAA) - a region where the role of glacial meltwater in marine biogeochemical cycles is largely unexplored - despite the fact that the CAA is a hotspot for glacial retreat and meltwater runoff to the ocean. Over the next 5 years, my group and I will work to quantify contemporary export of nutrients and carbon from glacial systems, and the associated impact of this export on marine processes and ecosystems. Specifically we will ask: 1) What is the source of biogeochemical constituents (nutrients, carbon) leaving the ice system? 2)What is the fate of glacial meltwater and its associated constituents in the coastal ocean? and 3) How does glacial meltwater impact marine microbial community production, structure, and function? To answer these questions we will conduct novel ice-to-ocean studies, combining field measurements of chemical species with molecular biological assays and laboratory experiments. This approach will address the impact of meltwater interactions close to the glacier termini and at broader regional scales, and target unanswered mechanistic questions. My program will be achieved by HQP using interdisciplinary techniques, bridging oceanography, geochemistry and microbial ecology. Together we will do this work in Jones Sound in the CAA, a region surrounded by glaciers and home to Inuit hamlet of Grise Fiord. The termini of tidewater glaciers here are highly productive waters, serving as hunting grounds for the hamlet. Understanding the drivers of marine production at the base of the food web, and the susceptibility of these drivers to climate change, is important to the long-term health of this northern community, and to coastal Arctic ocean functioning. Collectively, this research is a critical step towards revealing the role of melting glaciers on the marine carbon cycle in the past, present, and future.