The biogeochemistry of ocean-ice interaction around Greenland

在本项目中，我们将格陵兰岛海岸作为一个理想的研究对象，研究水文循环的变化如何影响海洋的地球化学和生产力。随着格陵兰冰盖（GrIS）的年排放量不断增加，一个关键问题是这种淡水外流如何影响格陵兰岛周围陆架海的生产力。GrIS是地球上第二大冰湖。当淡水从GrIS进入海洋时，它在岛屿周围的沿海沃茨中产生了强烈的物理和地球化学梯度。这些梯度在格陵兰的峡湾最为明显，按表面积计算，峡湾是最大的海洋碳汇之一。格陵兰的峡湾和陆架海也是国家重要渔业的所在地，其未来对格陵兰的经济至关重要。虽然人们普遍认为，冰川淡水输入影响区域海洋环流，但我们对融水释放的物理学和海洋生物地球化学长期变化之间的联系的理解仍处于起步阶段。政府间气候变化专门委员会（IPCC）目前感兴趣的一个主题是，在气候变暖的情况下，冰冻圈和海洋将如何在地球化学上相互作用。这里的主要目标将是确定格陵兰周围海洋淡水输入量增加所引起的物理和化学变化如何影响浮游植物的养分（大量营养素和微量营养素）供应，从而影响初级生产，通过将实地工作与理想化模型相结合，将确定三种主要不同淡水来源（地表径流、地下排放和冰山融化）的影响。河口混合过程的化学-这往往会导致快速变化的化学形式，从而营养物质的生物利用度-作为淡水与盐水混合将进行调查。将确定格陵兰周围受淡水影响区域的浮游植物群落的营养限制状况，从而评估水柱物理和化学组成同时发生变化的净影响，从而有可能从海洋环境初级生产变化的角度了解进入极地海洋的淡水增加的影响。

In this project we will use Greenland’s coast as an ideal target for a process study to investigate how changes to the hydrological cycle affect the biogeochemistry and productivity of the ocean.With increasing annual discharge from the Greenland Ice Sheet (GrIS), a critical question is how this outflow of freshwater affects the productivity of shelf seas around Greenland. The GrIS is the second largest Icesheet on Earth. As freshwater enters the ocean from the GrIS it creates strong physical and biogeochemical gradients in coastal waters around the island. These gradients are most pronounced in Greenland’s fjords which, by surface area, are among the largest of marine carbon sinks. Greenland’s fjords and shelf seas are also home to nationally important fisheries, the future of which is of pivotal importance for Greenland’s economy.Whilst it is widely recognized that freshwater inputs from glaciers affect regional ocean circulation, our understanding of links between the physics of meltwater release and long-term changes to marine biogeochemistry is in its infancy. A topic of present interest to the Intergovernmental Panel on Climate Change (IPCC) is how the cryosphere and ocean will interact biogeochemically in a warming climate. The main objective here will be to determine how the physical and chemical changes induced by increased freshwater inputs to the ocean around Greenland affect nutrient (macronutrient and micronutrient) availability to phytoplankton and thus primary production.By combining fieldwork with idealized models, the effects of the three main different freshwater sources (surface runoff, subsurface discharge and iceberg melt) will be determined. The chemistry of the estuarine mixing process- which often induces rapid shifts in the chemical form and thus bioavailability of nutrients- as freshwater mixes with saline water will be investigated. The nutrient-limitation status of phytoplankton communities in freshwater affected regions around Greenland will be determined, and the net effect of concurrent changes to the physical and chemical composition of the water column will thus be assessed.It will therefore be possible to understand the effects of increasing freshwater into the polar ocean in terms of changes to the primary production in the marine environment.