Spatial distribution of agricultural non-point source pollution load in Ningbo and its impact on the water quality of the first-level tributaries of three rivers
With the in-depth advancement of pollution control from industrial and urban sources,the impact of agricultural non-point source pollution on water quality has become increasingly prominent.To assess the impact of agricultural non-point source pollution load in Ningbo City on the water quality of the first-tier tributaries of the Three Rivers(Yongjiang,Yaojiang,and Fenghuajiang),this study is based on agricultural production data and water quality monitoring data within the catchment areas of the first-tier tributaries of the Three Rivers in Ningbo City for the year 2023.The research investigated the spatiotemporal evolution characteristics of agricultural non-point source pollution load and the water quality of the first-tier tributaries of the Three Rivers,as well as the response relationship between the two.The results indicated that rural domestic sewage was the main source of chemical oxygen demand(COD)and ammonia nitrogen emissions from agricultural sources,contributing 57.3% and 61.0%,respectively,while the contribution rate of crop cultivation to total phosphorus pollution reached 76.7% .There was a significant spatial variation in the agricultural non-point source pollution load in Ningbo City,with Gaoqiao Town having the highest COD and ammonia nitrogen pollution load per unit area,reaching 4 163.1 kg·km-2 and 1 136.7 kg·km-2,respectively,and Jiangshan Town having a total phosphorus pollution load per unit area as high as 397.2 kg·km-2.The water quality of the first-tier tributaries of the Three Rivers showed a seasonal variation trend,and there was a corresponding relationship between the agricultural non-point source pollution load per unit area of some catchment units and water quality.However,at the overall township level,there was no significant correlation between pollution load and water quality.Further analysis revealed that in the 15 control units with higher intensity of agricultural production activities,the COD,ammonia nitrogen,and total phosphorus pollution load per unit area were significantly correlated with the concentration of water environmental pollutants,with determination coefficients of 0.27,0.30,and 0.35,respectively,indicating a high degree of response of water quality to pollution load.This study clarifies the applicability of predicting water environmental quality based on the agricultural non-point source pollution load per unit area,providing a theoretical basis for the supervision and management of agricultural non-point source pollution in the economically developed industrial areas of the middle and lower reaches of the Yangtze River.
万方数据
维普
