Collaborative research: Sinking rates and nutritional quality of organic mater exported from sea ice; the importance of exopolymeric substances

合作研究：海冰输出有机物的沉降率和营养品质；

• 批准号: 1023140
• 负责人: Susanne Neuer
• 金额: $ 30.81万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1023140&HistoricalAwards=false
• 关键词: Collaborative; research; Sinking; rates; nutritional

Available data concerning the sinking rates of ice algae are highly divergent, while the characteristics of particles formed from other large organic pools in sea ice have received little study. As an initial step to remedy this situation, funds are provided to study the role of exopolymeric substances (EPS), produced by ice algae, in particle formation. The importance of EPS to particle coagulation and sinking rate is well established for temperate water columns. In sea ice, EPS comprise 20-70% of total particulate organic carbon, but their role in the sinking rate and composition of particles exported from sea ice is poorly understood. Based on previous studies, the PIs predict both positive and negative effects of EPS on particle sinking rate depending on EPS quantity. EPS also is predicted to increase the ratio of carbon to nitrogen (C:N) in the organic matter, which serves as a nutritional indicator. Based on documented trends in the EPS content of first-year Arctic sea ice, the PIs specifically predict slower sinking rates and higher C:N in particles produced after the export of ice algae, and from the upper levels of the ice column. They also predict slower sinking rates and higher C:N where snow cover is thicker. They will measure the sinking rates of particles released from melted sea-ice cores and test their hypotheses by relating the observed sinking rates to variables such as EPS concentration in the ice. Changes in the contribution of the sea-ice community to different flux periods will be investigated using microscopy and DNA-based molecular techniques. Finally, to help explain the spatial variability in the EPS content of sea ice, they will quantify EPS production rates of cultured ice algae as a function of light level. This work is designed to provide a conceptual framework for understanding and predicting spatial and temporal variability in the sinking rates and nutritional quality of particles released from Arctic sea ice in relation to variables measured in the ice such as: snow depth, chlorophyll, particulate organic carbon, and EPS. The knowledge resulting from this study will contribute to our understanding of the Arctic Ocean carbon cycle and how it may be modified in response to climate variability.

关于冰藻下沉速率的现有数据差异很大，而海冰中其他大型有机池形成的颗粒的特征却很少受到研究。作为解决这一问题的第一步，我们提供资金来研究冰藻产生的胞外聚合物（EPS）在颗粒形成中的作用。对于温带水柱，EPS 对颗粒凝结和下沉速率的重要性已得到充分证实。在海冰中，EPS 占总颗粒有机碳的 20-70%，但它们在海冰排出颗粒的下沉速率和成分中的作用却知之甚少。根据之前的研究，PI 预测了 EPS 对颗粒下沉率的正面和负面影响，具体取决于 EPS 数量。 EPS 还预计会增加有机物中的碳氮比 (C:N)，这是一项营养指标。根据第一年北极海冰 EPS 含量记录的趋势，PI 特别预测了冰藻出口后以及冰柱上层产生的颗粒中下沉速度较慢和 C:N 较高。他们还预测，在积雪较厚的地方，下沉速度较慢，C:N 较高。他们将测量融化的海冰芯释放的颗粒的下沉速率，并通过将观察到的下沉速率与冰中 EPS 浓度等变量相关联来检验他们的假设。将使用显微镜和基于 DNA 的分子技术研究海冰群落对不同通量周期的贡献变化。最后，为了帮助解释海冰 EPS 含量的空间变异性，他们将量化养殖冰藻的 EPS 生产率作为光照水平的函数。这项工作旨在提供一个概念框架，用于理解和预测北极海冰释放颗粒的下沉速率和营养质量的时空变化，与冰中测量的变量相关，例如：雪深、叶绿素、颗粒有机碳和 EPS。这项研究获得的知识将有助于我们了解北冰洋碳循环以及如何改变它以应对气候变化。