Results of Porewater Oxidation Trials to Determine Dissolved Total Hg at Younger Lagoon Reserve, Santa Cruz California, USA (2019-2023)

This “Porewater-Oxidation” dataset was prepared to accompany the publication "Improved Total Mercury Analysis in High C and S Estuarine Porewaters using Longer Oxidation Times", Calvin et al., in prep. The overlying water and porewater analyzed to produce the data provided here was collected at the University of California Natural Reserve System’s Younger Lagoon Reserve, doi: (10.21973/N3894D). Sampling sites included Beach Zone (BZ; 36.949380 N, -122.067624 W), at the southern edge of the lagoon, characterized by sandy sediment and a close connection to the ocean and East Fork (EF; 36.951483 N, -122.066275 W), at the northern boundary of the lagoon, characterized by organic-rich, clay sediment and spatial proximity to agricultural sites. Sampling events took place in December 2019, April 2020, October 2020, and September 2023. This dataset contains porewater dissolved total mercury (HgT) concentrations accompanied by porewater acid volatile sulfide (AVS) concentrations. Other characteristics of overlying and porewater from the same sampling dates also include: pH, oxygen saturation, temperature, and salinity. The dataset provided here reports the HgT concentrations that resulted from oxidative digestion trials comparing EPA Method 1631e to a heated water bath and extended oxidation time (14-day and 21-24-day) room temperature digestions. The investigation was designed to reveal conditions that would best oxidize ligands while minimizing the reagent blank and was conducted with a range (0.25-5% v/v) of bromine monochloride (BrCl) concentrations. A 24-day digestion allowed more HgT to be detected compared to a 14-day digestion or a heated water bath.

本“孔隙水氧化（Porewater-Oxidation）”数据集为配合论文《采用更长氧化时长优化高碳硫河口孔隙水总汞分析方法》（Calvin等，待发表）而构建，论文英文原标题为"Improved Total Mercury Analysis in High C and S Estuarine Porewaters using Longer Oxidation Times"。本数据集所用的上覆水与孔隙水样品采集自加州大学自然保护区系统（University of California Natural Reserve System）扬潟湖保护区（Younger Lagoon Reserve），样品DOI编号为10.21973/N3894D。采样点位包括两处：其一为滩涂带（Beach Zone, 缩写BZ），位于潟湖南端，坐标为36.949380°N，122.067624°W，沉积物以砂质为主，与海洋连通性极佳；其二为东叉（East Fork, 缩写EF），位于潟湖北界，坐标为36.951483°N，122.066275°W，沉积物为富含有机质的黏土，毗邻农业区域。采样工作分别于2019年12月、2020年4月、2020年10月及2023年9月开展。本数据集包含孔隙水溶解态总汞（dissolved total mercury, HgT）浓度数据，同步配套孔隙水酸挥发性硫化物（acid volatile sulfide, AVS）浓度数据。同期采集的上覆水与孔隙水的其他特征参数还包括：pH值、氧饱和度、温度及盐度。本数据集所收录的HgT浓度来自氧化消解对比实验，对比方案包括EPA 1631e方法、恒温水浴消解，以及延长氧化时长的室温消解（14天与21~24天消解）。本研究旨在筛选出既能充分氧化配体、又能最大限度降低试剂空白的最优消解条件，实验采用了0.25%~5%体积分数的一氯化溴（bromine monochloride, BrCl）作为氧化剂。相较14天消解与恒温水浴消解方案，24天消解可检出更多的总汞。