Mercury Imports and Exports of Four Tidal Wetlands in the Sacramento Valley, California

The California Department of Water Resources (DWR) measured import and export loads of methylmercury (MeHg) and total mercury (THg) at four tidal wetlands in the Sacramento Valley of California to comply with the Central Valley Regional Water Quality Control Board’s Delta Methylmercury Total Maximum Daily Load (TMDL). In addition to mercury, DWR collected organic carbon, total suspended sediment, chlorophyll-a, temperature, dissolved oxygen, specific conductance, turbidity, total chlorophyll, velocity, level, and flow data. To do this, three sets of data were collected: 1) velocity, level, and flow data were collected continuously using an Acoustic Doppler Current Profiler, 2) continuous temperature, specific conductance, salinity, dissolved oxygen, turbidity, and total chlorophyll were collected using a water quality sonde, and 3) THg, MeHg, organic carbon, total suspended sediment, and chlorophyll-a were collected via grab samples either by sampling pole or flow-weighted composites with an autosampler.

加州水资源部（California Department of Water Resources, DWR）为满足中央谷区域水质控制委员会（Central Valley Regional Water Quality Control Board）发布的《三角洲甲基汞总最大日负荷（Delta Methylmercury Total Maximum Daily Load, TMDL）》合规要求，在加利福尼亚州萨克拉门托谷的4处潮汐湿地开展了甲基汞（methylmercury, MeHg）与总汞（total mercury, THg）的进出口负荷测算工作。除汞类监测指标外，该部门还采集了有机碳、总悬浮沉积物、叶绿素a、水温、溶解氧、比电导率、浊度、总叶绿素、流速、水位及流量数据。本次数据采集共分为三组：1. 采用声学多普勒流速剖面仪（Acoustic Doppler Current Profiler）持续采集流速、水位与流量数据；2. 借助水质多参数探头（water quality sonde）持续采集水温、比电导率、盐度、溶解氧、浊度及总叶绿素数据；3. 通过采样杆采集瞬时水样，或利用自动采样器采集流量加权混合水样，获取总汞、甲基汞、有机碳、总悬浮沉积物及叶绿素a样本。