Biogeochemical and ecological consequences of the freeze-melt cycle of freshwater ice

世界上有一半的湖泊会定期结冰，但结冰的时间每年都在缩短。这种模式将在地方和全球层面产生巨大影响。虽然冰的存在，在其持续时间的变化，并改变其融化的时间是众所周知的影响许多重要的生物活动在极地海洋生态系统，有很少的信息，湖冰如何影响地球化学和生态的北方淡水。大多数北方湖泊都很浅，大部分水量在冬季冻结，同时捕获化合物，气体和生物体，并提供维持生物生产的冰水界面。该项目将解决新出现的迫切需要，了解与加拿大北极湖冰有关的碳、营养物质和浮游生物食物网。该研究计划已计划作为两个博士和两个硕士学生，谁将在水产科学广泛的技能毕业的培训项目。研究将在努纳武特的剑桥湾周围进行，在那里，在20公里半径范围内发现了100多个大小和深度不同的湖泊。该项目将解决首要问题：北方淡水生态系统如何应对冰的冻结、存在和融化。冬季冰盖将两个开放水域季节联系起来，因此出现了另一个关键问题：冬季期间冰中的物质和气体是否不断积累和产生，或者是否会发生突然变化，例如极地冬季之后太阳辐射增加？鉴于这些沃茨位于含有永久冻土的集水区，人们对以下问题特别感兴趣：湖冰将如何与融化的永久冻土释放出的越来越多的有机和无机颗粒反应？因此，该项目将解决这样一个问题：这些颗粒的内容是被捕获并转移到冰中并用于生物生产，还是转化为温室气体？通过表征有机和无机碳和营养状况，以及藻类和它们在每个湖泊的冰和水之间的分配，以及它们被南极消费者的消费，这项研究将产生北极淡水生态系统的新视野，这是第一次考虑冬季冰盖对北极湖泊功能的影响。它将与整个北极圈进行的多项永久冻土和湖泊研究联系起来，并产生将影响政策和科学的信息。

Half of the world's lakes freeze periodically, but the duration of freezing shortens each year. This pattern will have vast consequences at a local and global level. While the presence of ice, changes in its duration, and altered timing of its melt are known to affect many important biological activities in polar marine ecosystems, there is very little information regarding how lake ice influences the biogeochemistry and ecology of northern freshwaters. Most northern lakes are shallow with much of their water volume freezing in winter, concurrently trapping compounds, gases and organisms and providing an ice-water interface that sustains biological production. This project will address the emerging and pressing need for an understanding of carbon, nutrients and plankton food webs associated with lake ice in Arctic Canada. The research program has been planned as projects for the training of two PhD and two MSc students, who will graduate with broad skills in the aquatic sciences. Research will be carried out around Cambridge Bay, Nunavut, where >100 lakes of different size and depth are found within a 20-km radius. The project will address the overarching question: how do northern freshwater ecosystems respond to the freezing, presence, and melting of ice. Winter ice cover links two open water seasons, and thus another key question arises: is there a constant accumulation and production of material and gases in the ice during winter, or are there abrupt changes, for example when solar radiation increases after the polar winter? Given that these waters lie in catchments containing permafrost, there is a particular interest in the question: how will lake ice react with the increasing amount of organic and inorganic particles released from thawing permafrost? The project will therefore address the question: is the content of these particles trapped and transferred in the ice and made available to biological production, or is it transformed into greenhouse gases? By characterizing the organic and inorganic carbon and nutrient regimes, as well as algae and their partitioning between ice and water at each lake, and their consumption by planktonic consumers, this research will generate a new vision of Arctic freshwater ecosystems, which for the first times accounts for the effect of winter ice cover for the functioning of Arctic lakes. It will link with the multiple permafrost and lake studies taking place throughout the circumpolar North and produce information that will affect both policy and science.