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

淡水冰冻融循环的生物地球化学和生态后果

• 批准号: RGPIN-2019-05279
• 负责人: Rautio, Milla
• 金额: $ 4.01万
• 依托单位: Université du Québec à Chicoutimi
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765443
• 关键词: Biogeochemical; ecological; consequences; freeze; melt

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.

世界上一半的湖泊会定期结冰，但结冰时间逐年缩短。这种模式将在地方和全球层面产生巨大影响。虽然已知冰的存在、其持续时间的变化以及其融化时间的改变会影响极地海洋生态系统中的许多重要生物活动，但关于湖冰如何影响北部淡水的生物地球化学和生态的信息却很少。大多数北方湖泊都很浅，大部分水量在冬季结冰，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。该项目将解决对了解与加拿大北极地区湖冰相关的碳、营养物和浮游生物食物网的新兴和迫切需求。该研究计划计划作为培训两名博士生和两名硕士生的项目，他们毕业时将具备水生科学方面的广泛技能。研究将在努纳武特地区的剑桥湾周围进行，那里20公里半径内发现了超过100个不同大小和深度的湖泊。该项目将解决一个首要问题：北部淡水生态系统如何应对冰的冻结、存在和融化。冬季冰盖连接着两个开放水域季节，因此出现了另一个关键问题：冬季冰中物质和气体是否持续积累和产生，或者是否发生突然变化，例如极地冬季后太阳辐射增加？鉴于这些水域位于含有永久冻土的集水区，人们对以下问题特别感兴趣：湖冰将如何与永久冻土融化释放的不断增加的有机和无机颗粒发生反应？因此，该项目将解决这样一个问题：这些颗粒的含量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，以及藻类及其在每个湖泊的冰和水之间的分配，以及浮游消费者对它们的消耗，这项研究将产生北极淡水生态系统的新愿景，这将首次解释冬季冰盖对北极湖泊功能的影响。它将与在整个北极地区进行的多项永久冻土和湖泊研究联系起来，并产生影响政策和科学的信息。