Openly accessible global-scale surface water chemistry datasets are urgently needed to detect widespread trends and problems, to help identify their possible solutions, and to determine critical spatial data gaps where more monitoring is required. Existing datasets are limited with respect to availability, sample size and/or sampling frequency, and geographic scope. These limitations inhibit researchers from tackling emerging transboundary water chemistry issues – for example, the detection and understanding of delayed recovery from freshwater acidification. Here, we begin to address these limitations by compiling the global Surface Water Chemistry (SWatCh) database, available on Zenodo (https://doi.org/10.5281/zenodo.6484939; Rotteveel and Heubach, 2021). We collect, clean, standardize, and aggregate open-access data provided by six national and international programs and research groups (United Nations Environment Programme; Hartmann et al., 2019; Environment and Climate Change Canada; the United States of America National Water Quality Monitoring Council; the European Environment Agency; and the United States National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Network) in order to compile a database containing information on sites, methods, and samples, and a geospatial information system (GIS) shapefile of site locations. We remove poor-quality data (e.g., values flagged as “suspect” or “rejected”), standardize variable naming conventions and units, and perform other data cleaning steps required for statistical analysis. The database contains water chemistry data for streams, rivers, canals, ponds, lakes, and reservoirs across seven continents, 24 variables, 33 722 sites, and over 5 million samples collected between 1960 and 2022. Similar to prior research, we identify critical spatial data gaps on the African and Asian continents, highlighting the need for more data collection and sharing initiatives in these areas, especially considering that freshwater ecosystems in these environs are predicted to be among the most heavily impacted by climate change. We identify the main challenges associated with compiling global databases – limited data availability, dissimilar sample collection and analysis methodology, and reporting ambiguity – and provide recommended solutions. By addressing these challenges and consolidating data from various sources into one standardized, openly available, high-quality, and transboundary database, SWatCh allows users to conduct powerful and robust statistical analyses of global surface water chemistry.

中文翻译：

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地表水化学 (SWatCh) 数据库：一个标准化的全球水化学数据库，以促进大样本水文研究

迫切需要可公开访问的全球尺度地表水化学数据集，以检测普遍的趋势和问题，帮助确定可能的解决方案，并确定需要更多监测的关键空间数据差距。现有数据集在可用性、样本大小和/或采样频率以及地理范围方面受到限制。这些限制阻碍了研究人员解决新出现的跨界水化学问题——例如，检测和理解从淡水酸化中延迟恢复的问题。在这里，我们开始通过编译 Zenodo 上提供的全球地表水化学 (SWatCh) 数据库来解决这些限制（https://doi.org/10.5281/zenodo.6484939；Rotteveel 和 Heubach，2021 年）。我们收集、清洁、标准化、并汇总六个国家和国际计划和研究小组（联合国环境规划署；Hartmann 等人，2019 年；加拿大环境与气候变化；美国国家水质监测委员会；欧洲环境署）提供的开放获取数据; 和美国国家科学基金会 McMurdo Dry Valleys 长期生态研究网络），以便编译一个数据库，其中包含有关站点、方法和样本的信息，以及站点位置的地理空间信息系统 (GIS) shapefile。我们删除质量较差的数据（例如，标记为“可疑”或“拒绝”的值），标准化变量命名约定和单位，并执行统计分析所需的其他数据清理步骤。该数据库包含溪流、河流、运河、池塘的水化学数据，1960 年至 2022 年间，跨越七大洲的湖泊和水库、24 个变量、33722 个地点和超过 500 万个样本收集。与先前的研究类似，我们确定了非洲和亚洲大陆的关键空间数据差距，强调需要更多数据这些地区的收集和共享举措，特别是考虑到这些环境中的淡水生态系统预计将成为受气候变化影响最严重的地区之一。我们确定了与编译全球数据库相关的主要挑战——有限的数据可用性、不同的样本收集和分析方法以及报告的模糊性——并提供推荐的解决方案。通过应对这些挑战并将来自不同来源的数据整合到一个标准化、公开可用、高质量和跨界的数据库中，