Spatiotemporal variation and driving factors of eutrophication in Xincun Lagoon, Hainan, China

Environmental issues in Xincun Lagoon, Hainan, China, have increased in severity. Therefore, we conducted a four-season environmental survey of Xincun Lagoon from 2016 to 2017, selected 10 eutrophication-related parameters, and determined the eutrophication status of the lagoon using eutrophication index assessment. Principal component analysis identified salinity, temperature, nutrient salts (active phosphate and inorganic nitrogen), and chlorophyll a as the main factors controlling the eutrophication characteristics of Xincun Lagoon. Further analysis revealed that the degree of eutrophication outside Xincun Lagoon was lower than that within the lagoon and the degree of eutrophication along the south coast was lower than that along the north coast. Eutrophication was the highest in fall, followed by winter, spring, and summer. Nutrient inputs and other contaminants from terrestrial and marine culture represent the main causes of lagoon eutrophication. •Ten parameters were selected to evaluate the eutrophication status of Xincun Lagoon.•Salinity, temperature, nutrient salts, and chla primarily control eutrophication.•The degree of eutrophication outside Xincun Lagoon is lower than inside.•Eutrophication is the highest in autumn, followed by winter, spring, and summer.•These results provide a reference for the environmental management of the lagoon.