Impact of changes in sea ice extent on primary productivity in the Southern Ocean: links between the iron and carbon cycles in fast ice and the marginal ice zone

A times series of data was collected from coastal (land-fast) sea ice at Davis Station, Eastern Antarctica (68 degrees 34' 36" S, 77 degrees 58' 03" E; Figure 1) from November 16 to December 2, 2015. Sea ice temperature and salinity, as well as macro-nutrients (nitrate NO3-, nitrite NO2-, ammonium NH4+, phosphate PO43- and DSi), particulate organic carbon (POC) and chlorophyll a (Chla) in the sea ice were measured six times in 16 days of austral spring and early summer (Nov. 16, Nov. 20, Nov. 23, Nov. 26, Nov. 29, and Dec. 2; in days of the year, 320, 325, 327, 330, 333, and 336). Depths were measured from the top of the ice cores. Seawater below the ice was also sampled for comparison.Samples of snow, sea ice, brine and under-ice seawater were collected under trace metal clean conditions near Davis station during the transition of sea ice from winter to spring conditions (October 2015), on a regular basis (every 4 days) for 3 weeks. 6 sampling events were successfully achieved. The list of parameters collected during the fast ice study include in situ temperature, ice texture, pH, oxygen, iron and Chla, Br/I, carbonate, nutrients and POC, incubations with stable N and C isotopes. Samples are currently returning on V3 and will be analysed in the US, Belgium and Australia in the coming months. The biogeochemical observations will allow us to determine the roles of light versus iron in the initiation of the spring bloom in this region, and the role of the melting fast ice in fertilising the spring time primary production.

本数据集采集自南极东部戴维斯站（Davis Station，68°34′36″S，77°58′03″E；图1）沿岸固着海冰（land-fast sea ice）的时间序列数据，采集时段为2015年11月16日至12月2日。在南极春季初夏的16天内共计开展6次采样（对应日期分别为11月16日、11月20日、11月23日、11月26日、11月29日及12月2日，即年积日320、325、327、330、333及336），测定了海冰温度与盐度，同时涵盖宏营养盐（硝酸盐NO₃⁻、亚硝酸盐NO₂⁻、铵盐NH₄⁺、磷酸盐PO₄³⁻与溶解态硅酸盐DSi）、颗粒有机碳（POC）及海冰内叶绿素a（Chla）的检测。冰芯深度以冰体顶部为基准起算。此外同步采集冰下海水样品以作为对照。2015年10月，在海冰由冬季状态向春季状态过渡期间，研究团队于戴维斯站附近采用痕量金属洁净采样条件，每隔4天开展定期采样，持续三周并成功完成6次采样，获取了雪、海冰、卤水及冰下海水样品。本次固着海冰研究的测定参数包括原位温度、冰体结构、pH值、溶解氧、铁元素与叶绿素a、溴碘比值、碳酸盐体系、营养盐及颗粒有机碳，同时进行了稳定性氮与碳同位素标记培养实验。当前样品正通过V3航次运回，未来数月内将分别在美国、比利时与澳大利亚开展分析工作。本次生物地球化学观测结果将用于明确光照与铁在该区域春季水华启动过程中的相对作用，以及融化的固着海冰在春季初级生产的营养补给效应中所承担的功能。