Chinese scientists have constructed a database of nutrient concentrations in Chinese lake sediments, which reveals their historical changes and can be used to predict water quality and environmental conditions in various lake areas.

Lakes provide important reserves of freshwater resources for human survival and development, and an increase or decrease in nitrogen and phosphorus concentrations can reflect the corresponding deterioration or improvement of water quality, said Chen Jianhui, leader of the researchers from the College of Earth and Environmental Sciences of Lanzhou University.

However, the relatively brief history of monitoring nutrient levels in Chinese lake waters limits the understanding of the causes of their eutrophication and constrains effective lake management. Fortunately, the nutrient concentrations in lake sediments can faithfully reflect the nutrient levels of lake waters and thus help reconstruct their historical evolution, according to Chen.

Using a compilation of published nutrient data from lake sediments and data from newly collected lake sediment cores, the research team, also composed of scientists from the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences (CAS) and Hainan University, obtained the historical records of changes in nitrogen and phosphorus concentrations of 69 lakes in six lake regions across China, and subsequently reconstructed trends in nutrient accumulation in Chinese lakes between 1850 and 2020.

The researchers also conducted a quantitative analysis of this database and existing datasets of climatic, economic, and environmental factors, and found that nitrogen concentrations in lakes generally show a decreasing trend from 2030 to 2100, while phosphorus concentrations will continue to increase in some lake districts.

These results provide a valuable reference for understanding changes in regional lake water quality and assessing the health of lake ecosystems. They also highlight the need for China to develop customized regional lake management strategies from zonal and elemental perspectives, according to the researchers.