Depth profiles of pore water constituents from sediment cores collected on the Louisiana Shelf of the Northern Gulf of Mexico during November 2020 on R/V Savannah cruise SAV-20-07

This data set reports depth profiles of pore water concentrations of dissolved inorganic carbon (DIC), orthophosphate (PO43-), ammonium (NH4+), total alkalinity (TA), carbon isotopic fractionation of DIC (13C-DIC), dissolved manganese (Mnd), dissolved calcium (Cad), reduced iron (Fe(II)), total dissolved Fe (Fed), and dissolved Fe(III) (Fe(III)d) by the difference of total dissolved Fe and Fe(II). These pore water data were obtained from sediment cores collected at five different stations on the Louisiana Shelf on the Northern Gulf of Mexico during the week of November 3-6, 2020 using an MC-800 multi-corer. These stations extend from the middle of the shelf offshore from Cocodrie, LA to the mouth of the Mississippi River North West Pass. All cores were processed within a few hours after collection. The field sampling was conducted during R/V Savannah cruise SAV-20-07. The pore waters were first extracted by slicing sediment cores of < 25 centimeters (cm) long and centrifugation of the pore waters under N2 atmosphere to avoid air contamination. Pore waters were then immediately filtered through 0.22-micrometer (um) PSE syringe filters under N2 atmosphere and either analyzed immediately onboard (Fe speciation, orthophosphate, DIC), preserved acidified with hydrochloric acid at 4 degrees Celsius (Cad, Mnd), frozen (ammonium), or preserved at 4 degrees Celsius after addition of HgCl2 (TA) until analysis. In addition, samples for TA and carbon isotopic analyses were preserved in glass bottles, whereas other samples were preserved in polypropylene containers. DIC was analyzed by flow injection analysis (Hall and Aller, 1992), orthophosphate, ammonium, and Fe speciation by spectrophotometry (Murphy and Riley, 1962; Strickland and Parsons, 1972; Stookey, 1970), TA by Gran titration (Gran, 1952), the carbon isotopic signature by isotope ratio mass spectrometry (Wang et al, 2018), and Mnd and Cad by ICP-MS (Magette et al., 2023 In preparation). \"nd\" in the spreadsheet is provided when samples were not analyzed for these species (\"nd\" = not determined).本数据集报告了溶解无机碳（dissolved inorganic carbon, DIC）、正磷酸盐（PO₄³⁻）、铵离子（NH₄⁺）、总碱度（total alkalinity, TA）、溶解无机碳的碳同位素分馏（¹³C-DIC）、溶解态锰（Mnd）、溶解态钙（Cad）、还原态铁（Fe(II)）、总溶解态铁（Fed）以及通过总溶解态铁与Fe(II)差值计算得到的溶解态三价铁（Fe(III)d）的孔隙水浓度深度剖面。 上述孔隙水数据采自2020年11月3日至6日期间，在墨西哥湾北部路易斯安那陆架5个不同站位使用MC-800型多管采泥器采集的沉积物岩芯。这些站位覆盖范围从路易斯安那州科科德里附近陆架中部延伸至密西西比河北水道河口。所有岩芯均在采集后数小时内完成前处理。本次野外采样由“萨凡纳号”科考船（R/V Savannah）航次SAV-20-07执行。 孔隙水的提取首先通过将沉积物岩芯切割为长度小于25厘米（cm）的段，随后在氮气气氛下离心分离孔隙水以避免空气污染。分离后的孔隙水立即在氮气气氛下通过0.22微米（μm）PSE针式过滤器过滤，随后根据检测指标分别进行保存与前处理：铁形态、正磷酸盐、DIC样品立即在船上现场分析；溶解态钙（Cad）、溶解态锰（Mnd）样品经盐酸酸化后于4摄氏度下保存；铵离子样品直接冷冻保存；总碱度（TA）样品加入氯化汞后于4摄氏度下保存，直至开展分析。此外，总碱度与碳同位素分析样品储于玻璃瓶中，其余样品均储于聚丙烯容器内。 DIC采用流动注射分析法测定（Hall与Aller, 1992）；正磷酸盐、铵离子及铁形态采用分光光度法测定（Murphy与Riley, 1962；Strickland与Parsons, 1972；Stookey, 1970）；总碱度采用Gran滴定法测定（Gran, 1952）；碳同位素特征采用同位素比值质谱法测定（Wang等, 2018）；溶解态锰（Mnd）与溶解态钙（Cad）采用电感耦合等离子体质谱法（ICP-MS）测定（Magette等, 2023, 待刊）。表格中“nd”表示对应指标未完成分析（“nd”即not determined，未测定）。