Datasets from Groundwater-Quality Data from the National Water-Quality Assessment Project, January through December 2014 and Select Quality-Control Data from May 2012 through December 2014

Groundwater-quality data were collected from 559 wells as part of the National Water-Quality Assessment Project of the U.S. Geological Survey National Water-Quality Program from January through December 2014. The data were collected from four types of well networks: principal aquifer study networks, which assess the quality of groundwater used for public water supply; land-use study networks, which assess land-use effects on shallow groundwater quality; major aquifer study networks, which assess the quality of groundwater used for domestic supply; and enhanced trends networks, which evaluate the time scales during which groundwater quality changes. Groundwater samples were analyzed for a large number of water-quality indicators and constituents, including major ions, nutrients, trace elements, volatile organic compounds, pesticides, radionuclides, and some special interest constituents (arsenic speciation, chromium (VI) and perchlorate). These groundwater quality data are tabulated in a U.S. Geological Survey Data Series Report DS-1063 which is available at https://dx.doi.org/10.3133/ds1063 and in this data release. Quality-control samples also were collected and select data from 2012-2014 are included in the report DS1063 and this data release. Data from the environmental and QC blank and replicate samples from the 2012-2013 sampling period were presented in Arnold and others (2016). Data from spike QC samples have not previously been published Data from VOC spike QC data from May 2012-December 2014 are published in this report (see larger work citation) and data release along with an analysis of QC data where detections in field blank samples, variability in replicate samples, and recoveries in VOC spike samples are described for the entire sampling period through the date covered in this report (May 2012-December 2014). Pesticide spike samples and analysis of recoveries will be presented in a later report. There are 42 tables that are part of the larger work citation. There are 9 tables in the text of the larger work citation and 33 external tables included in this data release. The 9 tables not included in the data release are summary tables derived from some of the other 33 tables. Tables in the text include table 1, Appendix 1 tables 1-1 and 1-2; Appendix 2 table 2-1, and Appendix 4 tables 4-1 through 4-6. Tables that are external files are tables 1 through 12; Appendix 4 tables 4-7 through 4-27. This compressed file contains 33 files of groundwater-quality data in ASCII text tab-delimited format and 33 corresponding metadata in xml format for wells sampled for the U.S. Geological Survey National Water-Quality Assessment Project.

本数据集为美国地质调查局（U.S. Geological Survey）国家水质计划下属的全国水质评估项目的组成部分，于2014年1月至12月期间从559口水井中采集地下水水质数据。本次数据覆盖四类井网：主要含水层研究井网，用于评估公共供水所用地下水的水质；土地利用研究井网，用于评估土地利用对浅层地下水水质的影响；大型含水层研究井网，用于评估生活供水所用地下水的水质；强化趋势监测井网，用于评估地下水水质变化的时间尺度。本次采集的地下水样品针对多项水质指标与组分开展实验室分析，涵盖常量离子、营养盐、痕量元素、挥发性有机化合物、农药、放射性核素，以及部分特殊关注组分（砷形态、六价铬与高氯酸盐）。上述地下水水质数据已整理收录于美国地质调查局数据系列报告DS-1063，可通过https://dx.doi.org/10.3133/ds1063获取，同时亦包含于本次数据发布包中。

本次研究同步采集了质控（Quality Control, QC）样品，报告DS1063与本次数据发布包中亦纳入2012年至2014年的部分筛选后数据。2012年至2013年采样周期的环境样品、质控空白样品与平行样数据已由Arnold等人（2016）公开发表。加标质控样品数据此前尚未正式发布，但本次报告与数据发布包中公开了2012年5月至2014年12月的挥发性有机化合物加标质控数据，并同步开展质控数据分析：内容覆盖整个采样周期（至本报告覆盖的2012年5月至2014年12月）内的野外空白样品检出情况、平行样变异程度与挥发性有机化合物加标样品的回收率表现。农药加标样品及其回收率分析将在后续研究报告中发布。

本关联研究成果共计包含42张表格：其中9张收录于关联研究正文，其余33张外部表格则包含于本次数据发布包中。未纳入本次数据发布包的9张表格为基于其余33张表格衍生的汇总统计表格。正文中的表格包括表1、附录1的表1-1与表1-2、附录2的表2-1，以及附录4的表4-1至表4-6。作为外部独立文件的表格包括表1至表12，以及附录4的表4-7至表4-27。

本次发布的压缩文件包含33个以ASCII文本制表符分隔格式存储的地下水水质数据文件，以及对应33份XML格式的元数据文件，相关数据为美国地质调查局全国水质评估项目所采样的水井相关信息。