Abstract:
The spatialtemporal distribution characteristics, influencing factors and nutrient limitation in Xiamen coastal waters were analyzed, and the eutrophication conditions were evaluated, based on fifteen cruises in 2016-2020. The results showed that the nutrient concentrations were higher in the coastal waters, and decreased gradually offshore. Specifically, the concentrations of dissolved inorganic nitrogen (DIN) distributed in order of Jiulong River Estuary > West Sea > Tongan Bay > the south sea of Xiamen > the east sea of Xiame >Dadeng seawater, but the concentration of dissolved inorganic phosphorus (DIP) followed the order of Tongan Bay > the west sea of Xiamen > Jiulong River Estuary > the east sea of Xiamen > the south sea of Xiamen > Dadeng seaarea. The results also showed that the average concentrations of nutrients decreased annually and they reached the highest in dry season and the lowest in the wet season. The averaged N∶P molar ratio was 40 in Xiamen coastal area, indicating the potential P-limitation. The levels of eutrophication were decreased yearly from 2016 to 2020. The areas of high eutrophication index
E) were mainly located in the sea area near Jiulong River Estuary and the west sea of Xiamen. The eutrophication index that negatively correlated with salinity indicates the eutrophication impacts of terrestrial nutrients to the study area.