Identifying the carbon that matters: chemical controls on organic matter aggregation (COMA)

威德尔海和邻近的南极南部绕极洋流是全球初级生产和碳收支的重要贡献者。生物泵及其从光层到海底的颗粒有机物(POM)的运输，以及南大洋CO2和顽固性溶解有机物(DOM)的形成和向下转移是大气CO2向长期储存碳转移的关键调节因素。DOM经历聚集并与颗粒(如细胞、粪便颗粒和碎屑)结合，这有助于碳的沉积和固定，并在全球碳循环中创造一个主要的汇。尽管聚集具有重要的作用，但人们对低分子有机物和胶体物质的积累速率和结合知之甚少。为了研究溶解有机物质、胶体有机物质和颗粒有机物质之间的转化，SPP1158建议“确定重要的碳：有机物聚集的化学控制(COMA)”集中于表层海水中的有机物质。样本将在2022年南极夏秋期间和2022年春季期间在极地探险队HAFOS(混合南极浮标和海洋观测站)上采集。将对样品进行化学表征，并测试其聚集行为和速率。然后，这些分析数据可以与环境数据和探险队测量的出口通量相结合，以得出关于极地碳循环的结论。COMA项目涉及SPP1158方案的中心主题，即更好地了解南大洋的生物碳泵和评估有助于大气二氧化碳长期储存的过程。

The Weddell Sea and the adjacent southern Antarctic Circumpolar Current are important contributors to the global primary production and carbon budget. The biological pump and its transport of particulate organic matter (POM) from the photic zone to the ocean floor and the formation and downward transfer of CO2 and recalcitrant dissolved organic matter (DOM) in the Southern Ocean are key regulators of the transfer of atmospheric CO2 to long-term storage of carbon. DOM undergoes aggregation and binds to particles (e.g., cells, faecal pellets and detritus), which contributes to deposition and sequestration of carbon and creates a major sink in the global carbon cycle. Despite of this significant role of aggregation, very little is known about the accumulation rates and binding of low molecular organic matter and colloidal matter. To study the transition between dissolved, colloidal and particulate organic matter, this SPP1158 proposal “Identifying the carbon that matters: chemical controls on organic matter aggregation (COMA)” focusses on organic matter from surface seawater. Samples will be taken on the Polarstern expeditions HAFOS (Hybrid Antarctic Float and Ocean Observatory) during the Austral summer / autumn of 2022 and "IslandImpact" during the Austral spring of 2022. Samples will be chemically characterized and tested for their aggregation behaviour and rates. These analytical data can then be integrated with environmental data and measured export fluxes from the expeditions in order to draw conclusions about the polar carbon cycle. The COMA project addresses central themes of the SPP1158 programme, namely to achieve a better understanding of biological carbon pump of the Southern Ocean and assessment of processes that contribute to the long term storage of atmospheric CO2.