Porewater nutrients of the Northeast Greenland (NEG) shelf sediments from POLARSTERN cruise PS109@en

Sediment porewater chemistry (nutrient, DIC, sulfide and sulfate) on the Northeast Greenland shelf were assessed with R/V Polarstern during PS109 between September and October 2017 using two cores with pre-drilled holes mounted on a multiple corer (MUC) a camera-equipped multiple corer (TV-MUC; core area 0.007 m²). Upon arrival on deck, Rhizon samplers were inserted carefully into the holes with intervals of 1 cm until 10 cm sediment depth, and 2 cm intervals until 20 cm sediment depth to extract the sediment porewater. To get a total of 9 ml/l porewater for each depth interval, the porewater from both cores was pooled for each depth. For the analysis of DIC, 2 ml/l porewater from each depth was transferred to a glass vial which had been pre-treated with HgCl₂ and stored at 4°C. DIC concentrations were measured using a flow injection system equipped with the Spark Optimas auto-sampler (model 820, Ambacht, Netherlands). For the determination of porewater nutrients, 4 ml/l of porewater was sampled with acid-washed Sarstedt Vials and stored at -20°C. In the laboratory, 4 ml/l was subsampled for phosphate, silicate and ammonium, while 1 ml/l was subsampled for nitrate and nitrite, and subsequently analyzed with a Continuous Segmented Flow Analyser (QuAAtro39, SEAL Analytical, Norderstedt, Germany).2017年9月至10月期间，科考船“极星号（R/V Polarstern）”在格陵兰东北陆架开展航次PS109，对该区域沉积物孔隙水化学特征（涵盖营养盐、溶解无机碳（Dissolved Inorganic Carbon, DIC）、硫化物与硫酸盐）进行探测。本次采样采用搭载预钻孔的多管取样器（Multiple Corer, MUC）及带摄像系统的多管取样器（TV-MUC，取样面积0.007 m²），共获取2根沉积物岩心。岩心被送至甲板后，使用Rhizon采样器小心插入预钻孔中：沉积物深度0~10 cm区间内采样间隔为1 cm，10~20 cm区间内采样间隔为2 cm，以此提取沉积物孔隙水。为获取每个深度层共计9 mL的孔隙水样品，将两根岩心对应深度的孔隙水混合富集。针对溶解无机碳（DIC）分析，取每个深度层的2 mL孔隙水转移至经氯化汞（HgCl₂）预处理过的玻璃样品瓶中，并于4℃条件下冷藏保存；DIC浓度采用搭载Spark Optimas自动进样器（型号820，荷兰阿姆赫特）的流动注射分析系统进行测定。对于孔隙水营养盐的测定，取4 mL孔隙水装入经酸洗的Sarstedt样品瓶中，于-20℃条件下冷冻保存。在实验室阶段，分取4 mL样品用于磷酸盐、硅酸盐与铵态氮的分析，另分取1 mL样品用于硝态氮与亚硝态氮的分析，后续采用连续流动分析仪（QuAAtro39，德国诺德施泰特SEAL Analytical公司）完成全部检测。