Estimated nutrient and sediment concentrations from major rivers in Illinois based on continuous monitoring from October 1, 2015, through September 30, 2021

During water years 2016-2021 (a water year begins on October 1 and ends on September 30 and is designated by the year in which it ends), the U.S. Geological Survey (USGS), in cooperation with the Illinois Environmental Protection Agency (Illinois EPA), operated continuous monitoring stations on eight of the major rivers in Illinois to better quantify nutrient and sediment loadings from the State of Illinois to the Mississippi River. These eight rivers are the Illinois River, Rock River, Little Wabash River, Kaskaskia River, Vermilion River, Embarras River, Big Muddy River, and Green River. This data release presents estimates of daily nitrate, phosphorus, and suspended sediment concentrations and uncertainty over that period. The concentration estimates are based on a combination of discrete sampling and surrogate regression (imputation); see Hodson and others (2021a) for details on the imputation model. The data release comprises a single comma-separated values (csv) file containing daily timeseries of concentration and uncertainty for each monitoring station. These data supersede Hodson and others (2021b), which was based on data through water year 2020. Reference cited: Hodson, T.O., Terrio, P.J., Peake, C.S., and Fazio, D.J., 2021a, Continuous Monitoring and Bayesian Estimation of Nutrient and Sediment Loads from Illinois Watersheds, for water years 2016-2020: U.S. Geological Survey Scientific Investigations Report 2021-5092, https://doi.org/10.3133/sir20215092. Hodson, T.O., Terrio, P.J., Peake, C.S., and Fazio, D.J., 2021b, Modeled nutrient and sediment concentrations from major rivers in Illinois based on continuous monitoring from October 1, 2015, through September 30, 2020: U.S. Geological Survey data release, https://doi.org/10.5066/P9MS8OIH.

2016-2021水文年（water year，指始于每年10月1日、止于次年9月30日，并以结束年份作为标识的时段）期间，美国地质调查局（U.S. Geological Survey, USGS）联合伊利诺伊州环境保护局（Illinois Environmental Protection Agency, Illinois EPA），在伊利诺伊州境内8条主要河流布设连续监测站，以更精准地量化该州向密西西比河输入的营养盐与沉积物负荷。
本次监测覆盖的8条河流分别为伊利诺伊河、罗克河、小瓦巴什河、卡斯卡斯基亚河、弗米利恩河、安布拉萨斯河、大穆迪河与格林河。
本次发布的数据集包含该时段内每日硝酸盐、磷及悬浮沉积物浓度的估算值及其不确定性。浓度估算值基于离散采样与替代变量回归（插补）相结合的方法；插补模型的详细信息可参见Hodson等人（2021a）的研究成果。
本数据集仅包含单个逗号分隔值（comma-separated values, CSV）文件，存储了各监测站的浓度与不确定性的逐日时间序列数据。本次数据集替代了Hodson等人（2021b）的前期成果，后者仅基于截至2020水文年的监测数据。
引用文献如下：
1. Hodson, T.O., Terrio, P.J., Peake, C.S. 及 Fazio, D.J., 2021a，《2016-2020水文年伊利诺伊流域营养盐与沉积物负荷连续监测及贝叶斯估算》：美国地质调查局科学调查报告2021-5092，https://doi.org/10.3133/sir20215092。
2. Hodson, T.O., Terrio, P.J., Peake, C.S. 及 Fazio, D.J., 2021b，《基于2015年10月1日至2020年9月30日连续监测数据的伊利诺伊州主要河流模拟营养盐与沉积物浓度》：美国地质调查局数据发布成果，https://doi.org/10.5066/P9MS8OIH。