Changes of eutrophication degree in Dongshan Bay in China affected by the COVID-19 outbreak

Abstract

At the background of the outbreak of COVID-19 pandemic, water samples were collected in Dongshan Bay from 2019 to 2020, to study spatial and temporal changes of nutrients concentration and eutrophication degree with a new assessment model–PE3. Results showed that the spatial distribution of dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silica (DSi) generally decreased from Zhangjiang River estuary to the mouth of the bay and from west to east both in spring and summer. This pandemic seems to have little influence on the spatial distribution of DIP and DSi. However, DIN concentration decreased much greatly from 2019 to 2020, meanwhile N replaced P to be the potentially limited nutrient factor for the growth of phytoplankton. And average eutrophication degree of the bay assessed by PE3 increased from 1 in 1988 to 5 in 2008 and 6 in 2019 respectively, and decreased to 4 in 2020. It was suggested that after this pandemic, DIN concentration and eutrophication degree may decrease a lot in Chinese coastal waters.