Water chemistry data from 19644 seasonally ice-covered lakes

This dataset contains water chemistry monitoring data and lake morphometry data from 19644 lakes collected between 1960 and 2022 in Finland, Sweden, Norway, Canada and the United States, as well as ice phenology observations from 1107 lakes in the same regions. Data was sourced from governmental databases and non-profit organizations via data portals and data requests (see Metadata). The dataset contains over 5.3 million standardized and quality-controlled observations of dissolved oxygen, water temperature, total phosphorus, chlorophyll-a, water colour as well as sampling location, sampling date, sampling depth and key lake properties including lake altitude, surface area, mean depth and maximum depth. Ice phenology observations include ice freeze-up and breakup dates. We excluded lakes undergoing physical or chemical treatments against hypoxia, lakes in which experiments have been conducted (e.g. nutrient addition). and reservoirs.

The consumer of these data ("Data User" herein) should realize that misinterpretation of data may occur if used out of context of the original study. While substantial efforts are made to ensure the accuracy of data and associated documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is". The Data User should be aware, however, that data are updated periodically and it is the responsibility of the Data User to check for new versions of the data. The data authors, original data providers and the repository where these data were obtained shall not be liable for damages resulting from any use or misinterpretation of the data. The data user may not create derivatives of this dataset or re-distribute these data to a third party.

Note: if you would like to use this data in your own study, you must contact the author (joachim.jansen@helsinki.fi) to ensure compliance with requirements of the contributors to this synthesis dataset,