Haiyang Kaifa yu guanli (Jun 2023)
The Spatial Distribution Characteristics of Nutrients in the Coastal Waters of Laizhou Bay in Spring and Autumn 2020
Abstract
Based on the environmental monitoring data of Laizhou Bay in May (spring) and October (autumn), 2020, this paper had studied the spatial distribution characteristics of inorganic nitrogen (DIN) and reactive phosphate (DIP), the condition of seawater quality and eutrophication in Laizhou Bay, and completed the correlation analysis of nutrient and environmental factors. The results showed that in spring, the concentration of DIN ranged from 0.115 mg/L to 1.830 mg/L, which was higher near shore than far shore and higher in the west than in the east. In autumn, the concentration of DIN ranged from 0.009 mg/L to 2.070 mg/L, and the high value area was located near the estuary of the Yellow River. The DIP concentration in spring and autumn ranged from not detected to 0.009 mg/L and form 0.000 4 mg/L to 0.012 9 mg/L, respectively. Due to the influence of phosphorus load reduction policies such as "phosphorus control" and "phosphorus limit", the DIP concentration had always been at a low level. Affected by DIN concentration, 35.7% and 30.7% of the survey sites exceeded the second-class seawater quality standard in spring and autumn, respectively. In spring, 1.4% of the survey sites were slightly eutrophicated, located near the estuary of Xiaoqing River. In autumn, 1.6% of the survey sites were slightly eutrophic, located near the estuary of the Yellow River. And the other sites did not reach eutrophication level. The distribution characteristics of nutrients in Laizhou Bay were significantly correlated with various environmental factors, and the spatial distribution was affected by many factors.
