| Based on the survey data of four voyages in March, May, August and November 2021, this paper analyzed and summarized the nutrient content, distribution, structural change characteristics and key influencing factors in the sea area on the west side of Caofeidian, analyzed the correlation between its change characteristics and water quality parameters using multiple linear regression, and discussed the nutrient distribution characteristics using Redfield ratio. The results showed that the active silicate, TP and TN levels in the 2021 were higher in August than those in other periods, and the variation range between stations was larger. The average value of active silicate was 0.018 mg/L in March, in May, August and November, the average values of active silicate, TN and TP were 0.278 mg/l, 0.930 mg/l, 0.042 mg/l, 0.737 mg/l, 0.958 mg/l, 0.059 mg/l, 0.410 mg/l, 1.725 mg/l, 0.041 mg/L, respectively. In May and August, affected by the land−source substances carried by the land runoff, the distribution of nutrient salts decreased from the top side of the northwest bay to the southeast. The active silicate showed a significant negative correlation with salinity. TN and TP only showed a significant negative correlation with salinity in August. The main factors affecting the change of nutrient content were the land−source substances carried by the freshwater input of the land−source runoff of Jianhe and Shahe and the water exchange capacity, The second is the hydrological dynamic change caused by topographic factors. At the same time, the N/P content in the sea area is higher than that in the normal sea area due to the impact of human activities and runoff input, which is mainly related to the large amount of aquaculture wastewater nearby. |
