Human activities altered water N:P ratios in the populated regions of China

Being able to quantify nutrient stoichiometry in the waterbodies is especially important given its strong effects on a variety of ecological processes. China has made huge progress in the improvement of surface water quality, but the accompanying changes to water nutrient stoichiometry and implications are not well understood yet. Our results have shown that the water nutrient cycles have been decoupled in China's populated regions, and population density and GDP values in the same catchment are useful in explaining the variances of lake N:P stoichiometry in East China Lake Region. In other regions, water N and P tend to respond to the selected parameters in a similar way, leading to the poor prediction of N:P stoichiometry. With the progress of water management in China, a similar change of water nutrients and their stoichiometry as the developed countries is occurring, i.e., faster decrease of TP concentrations than TN, and continuing increase of N:P ratios. It is necessary for the managers to be aware of the quick and large-scale changes of nutrient stoichiometry in the water, since the ecological risk caused by the changes to the aquatic systems is still not well known.