Georeferenced Lake Nutrient Chemistry (GLNC) Database (updated March 2019)

This fileset includes files associated with the Georeferenced Lake Nutrient Chemistry (GLNC) Database, which is described in an open access publication in Scientific Data: Williams, J.J., Labou, S.G. 2017. A database of georeferenced nutrient chemistry data for mountain lakes of the Western United States. Scientific Data. 4: 170069. http://dx.doi.org/10.1038/sdata.2017.69 The Georeferenced Lake Nutrient Chemistry (GLNC) Database was constructed to create a spatially-extensive lake chemistry database needed to assess atmospheric nutrient deposition effects on Western U.S. mountain lakes. The database includes nitrogen and phosphorus water chemistry data spanning 1964-2015, with 148,336 chemistry results from 51,048 samples collected across 3,602 lakes in the Western U.S. Data were obtained from public databases, government agencies, scientific literature, and researchers, and were formatted into a consistent table structure. All data are georeferenced to a modified version of the National Hydrography Dataset Plus version 2. The database is transparent and reproducible; R code and input files used to format data are provided in an appendix. The database will likely be useful to those assessing spatial patterns of lake nutrient chemistry associated with atmospheric deposition or other environmental stressors. The most recent version of the database was uploaded March 23, 2019. Updates Log: Updated March 2019 (GLNC_March_2019.zip) to correct total phosphorus (TP) units in s18 (western lake survey). In March 2017 version, orig_units were incorrect (should have been ug/L). Values in 'value' field should be have been divided by 1000 to get units of mg P/L consistent with parameter "TP_mg/L" and units "mg P/L". This has now been corrected.

本文件集包含与地理参考湖泊营养盐化学（Georeferenced Lake Nutrient Chemistry, GLNC）数据库相关的全部文件。该数据库的相关信息已发表于《科学数据》（Scientific Data）的开放获取论文：Williams, J.J.、Labou, S.G. 于2017年发表的《美国西部山地湖泊地理参考营养盐化学数据库》，刊载于《科学数据》第4卷，文章编号为170069，DOI链接为http://dx.doi.org/10.1038/sdata.2017.69。

地理参考湖泊营养盐化学数据库旨在构建一套空间覆盖范围广泛的湖泊化学数据集，以用于评估大气营养盐沉降对美国西部山地湖泊的影响。该数据库涵盖1964年至2015年间的氮、磷水质化学数据，包含从美国西部3602个湖泊采集的51048份样本所对应的148336项化学检测结果。本数据集的数据来源包括公共数据库、政府机构、学术文献及科研人员，并已统一整理为标准表格结构。所有数据均已匹配至经过修订的国家水文增强数据集第二版（National Hydrography Dataset Plus Version 2）的地理坐标体系。

该数据库具备透明性与可复现性，数据整理所用的R代码及输入文件已以附录形式提供。本数据库可用于评估与大气沉降或其他环境胁迫因子相关的湖泊营养盐化学空间分布模式，具有较高的科研与应用价值。该数据库的最新版本于2019年3月23日上传发布。

更新日志：2019年3月发布的更新版本（压缩包名称为GLNC_March_2019.zip）修正了s18（西部湖泊调查）中总磷（Total Phosphorus, TP）的单位错误。在2017年3月版本中，orig_units字段标注的单位存在错误，正确单位应为微克每升（μg/L）。原'value'字段的数值需除以1000，才能与参数"TP_mg/L"及单位"mg P/L"保持一致，该问题现已完成修正。