Depth profiles of pore water constituents from sediment cores collected on the Louisiana Shelf of the Northern Gulf of Mexico during 2020, 2021, and 2022 on R/V Savannah cruises SAV-20-07, SAV-21-25, SAV-21-24, SAV-22-06, and SAV-22-11

<p><strong>2020 data:</strong><br /> 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.</p> <p><strong>2021 and 2022 data:</strong><br /> In July 2021, the pore water data were obtained from sediment cores collected with a MC-800 multi-corer at ten different stations on the Louisiana Shelf and slope in the Northern Gulf of Mexico during July 16-26, 2021. These stations span two transects, one from the middle of the shelf offshore from Cocodrie, LA to the mouth of the Mississippi River's South West Pass, and another one from North West Pass of the Mississippi River mouth to the south, across the slope. A single station (St. 15) was also sampled on the eastern side of the second transect in the transition from the shelf break to the mid-slope.</p> <p>In October 2021, the pore water data were obtained from sediment cores collected with a MC-800 multi-corer at twelve different stations on the Louisiana Shelf and slope in the Northern Gulf of Mexico between October 25 and November 10, 2021. These stations extend from the middle of the shelf offshore from Cocodrie, LA to the mouth of the Mississippi River's South West Pass. Two stations (St. 15 and St. 12) were also sampled on a second transect from the shelf break to the slope southeast of the Bird's Foot.</p> <p>In spring 2022, the pore water data were obtained from sediment cores collected with a MC-800 multi-corer at ten different stations on the Louisiana Shelf and slope in the Northern Gulf of Mexico during April 9-20, 2021. These stations span two transects, one from the middle of the shelf offshore from Cocodrie, LA to the mouth of the Mississippi River's South West Pass, and another from South West Pass of the Mississippi River mouth to the south, across the slope. Two stations (St. 15 and St. 12) were also sampled on a second transect from the shelf break to the slope southeast of the Bird's Foot.</p> <p>In summer 2022, the pore water data were obtained from sediment cores collected with a MC-800 multi-corer at eleven different stations on the Louisiana Shelf and slope in the Northern Gulf of Mexico during July 9 -23, 2022. These stations span two transects, one from the middle of the shelf offshore from Cocodrie, LA to the mouth of the Mississippi River's South West Pass, and another from South West Pass of the Mississippi River mouth to the south, across the slope. Two stations (St. 15 and St. 12) were also sampled on a second transect from the shelf break to the slope southeast of the Bird's Foot.</p> <p><strong>All data:</strong><br /> The pore waters were first extracted by slicing sediment cores of &lt; 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., 2025 In preparation).</p>**2020年数据：** 本批孔隙水数据采自2020年11月3日至6日期间，使用MC-800型多管沉积物取样器（multi-corer）在墨西哥湾北部路易斯安那陆架的5个不同站位采集的沉积物岩心。这些站位覆盖从路易斯安那州科科德里近岸陆架中部至密西西比河西北航道河口的区域。所有岩心均在采集后数小时内完成前处理，野外采样工作由“萨凡纳号”研究船（R/V Savannah）航次SAV-20-07执行。 **2021年与2022年数据：** 2021年7月16日至26日，研究人员使用MC-800型多管沉积物取样器，在墨西哥湾北部路易斯安那陆架与陆坡的10个不同站位采集沉积物岩心，由此获得本批孔隙水数据。这些站位涵盖两条断面：一条从路易斯安那州科科德里近岸陆架中部延伸至密西西比河西南航道河口，另一条从密西西比河河口西北航道向南跨越陆坡。在第二条断面的东侧，即陆架坡折至中陆坡的过渡区域，还额外布设了1个站位（St.15）。 2021年10月25日至11月10日，研究人员使用MC-800型多管沉积物取样器，在墨西哥湾北部路易斯安那陆架与陆坡的12个不同站位采集沉积物岩心，由此获得本批孔隙水数据。这些站位覆盖从路易斯安那州科科德里近岸陆架中部至密西西比河西南航道河口的区域。在“鸟足状三角洲”（Bird's Foot）东南部，从陆架坡折至陆坡的第二条断面上，还额外采集了2个站位（St.15与St.12）的样品。 2022年春季，研究人员使用MC-800型多管沉积物取样器，在墨西哥湾北部路易斯安那陆架与陆坡的10个不同站位采集沉积物岩心，采样时间为2021年4月9日至20日。这些站位涵盖两条断面：一条从路易斯安那州科科德里近岸陆架中部延伸至密西西比河西南航道河口，另一条从密西西比河河口西南航道向南跨越陆坡。在“鸟足状三角洲”（Bird's Foot）东南部，从陆架坡折至陆坡的第二条断面上，还额外采集了2个站位（St.15与St.12）的样品。 2022年7月9日至23日，研究人员使用MC-800型多管沉积物取样器，在墨西哥湾北部路易斯安那陆架与陆坡的11个不同站位采集沉积物岩心，由此获得本批孔隙水数据。这些站位涵盖两条断面：一条从路易斯安那州科科德里近岸陆架中部延伸至密西西比河西南航道河口，另一条从密西西比河河口西南航道向南跨越陆坡。在“鸟足状三角洲”（Bird's Foot）东南部，从陆架坡折至陆坡的第二条断面上，还额外采集了2个站位（St.15与St.12）的样品。 **全部数据处理流程：** 孔隙水的提取流程如下：首先将长度小于25厘米（cm）的沉积物岩心进行切片，随后在氮气（N₂）氛围下对孔隙水进行离心处理，以避免空气污染。随后立即在氮气氛围下，使用0.22微米（um）PSE注射器式滤器对孔隙水进行过滤，并根据检测需求采取不同的保存方式：① 立即在船上进行分析（检测铁形态、正磷酸盐、溶解无机碳（Dissolved Inorganic Carbon，DIC））；② 加入盐酸酸化后，于4摄氏度（℃）下保存（检测镉（Cd）、锰（Mn））；③ 冷冻保存（检测铵态氮）；④ 加入氯化汞（HgCl₂）后于4摄氏度下保存（检测总碱度（Total Alkalinity，TA）），直至后续分析。此外，用于总碱度与碳同位素分析的样品需储存在玻璃瓶中，其余样品则储存在聚丙烯容器内。溶解无机碳采用流动注射分析法进行检测（Hall和Aller，1992）；正磷酸盐、铵态氮与铁形态采用分光光度法进行检测（Murphy与Riley，1962；Strickland与Parsons，1972；Stookey，1970）；总碱度采用Gran滴定法进行检测（Gran，1952）；碳同位素特征采用同位素比值质谱法进行检测（Wang等，2018）；锰（Mn）与镉（Cd）则采用电感耦合等离子体质谱法（Inductively Coupled Plasma Mass Spectrometry，ICP-MS）进行检测（Magette等，2025，待刊）。