Shapefile of processed results from surface carbon and nitrogen analysis of sediment grab samples, Long Island Sound mapping project Phase II

Sediment grab samples were taken in summer of 2017 and 2018 using a modified van Veen grab sampler. A sub-sample of the top two centimeters was stored in a jar. Dried and homogenized splits of the samples were sent to the Cornell Isotope Laboratory (COIL) to be analyzed for carbon and nitrogen concentrations as well as stable isotopic compositions. Total carbon (TC), total nitrogen (TN), and δ15N were determined on an aliquot of untreated, dried homogenized sediments. In order to accurately determine total organic carbon (TOC) and δ13C, removal of carbonate is necessary. This was achieved through sequential treatments of the sediments with dilute hydrochloric acid until no bubbling was observed. The acidified sediments were then rinsed in deionized water and re-dried. In the Cornell Lab the samples were analyzed using a NC2500 elemental analyzer interfaced with a Thermo Delta V isotope ratio mass spectrometer (IRMS). The data is presented here as an ESRI shapefile. There is an accompanying Excel spreadsheet. Funding was provided by the Long Island Sound Mapping Fund administered cooperatively by the EPA Long Island Sound Study and the Connecticut Department of Energy and Environmental Protection (DEEP).

2017年与2018年夏季，研究人员采用改良型范维恩采泥器（modified van Veen grab sampler）采集沉积物抓样。采集所得的沉积物表层2厘米亚样本被密封保存于广口瓶中。经干燥均质化处理后的沉积物分样被送至康奈尔同位素实验室（Cornell Isotope Laboratory, COIL），开展碳、氮浓度及稳定同位素组成的分析测试。对未经过处理的干燥均质沉积物分装样本，测定了总碳（Total Carbon, TC）、总氮（Total Nitrogen, TN）以及δ¹⁵N值。为精准测定总有机碳（Total Organic Carbon, TOC）与δ¹³C值，需先去除沉积物中的碳酸盐成分：具体操作是将沉积物用稀盐酸依次处理，直至无气泡产生。经酸化处理后的沉积物随后用去离子水冲洗，并再次进行干燥。在康奈尔实验室中，研究人员采用NC2500元素分析仪与Thermo Delta V同位素比值质谱仪（Isotope Ratio Mass Spectrometer, IRMS）联机的测试系统对样本完成分析。本数据集以ESRI形状文件（ESRI shapefile）格式提供，同时附带一份Excel电子表格。本研究的资助资金由长岛海湾绘图基金提供，该基金由美国环境保护署（EPA）长岛海湾研究项目与康涅狄格州能源与环境保护部（Connecticut Department of Energy and Environmental Protection, DEEP）联合管理。