Estimating the non-point source pollution load flux of the bay

Abstract

Based on the increase in the pollution of the bay environment and the environmental protection concepts of "coordinated watershed-estuary-bay management" and "working on the land to protect the sea considering both seas and rivers", a nonpoint source pollution load model was constructed by determining the intensities of nonpoint pollution sources and systematically analyzing their characteristics. After introducing rainfall and slope factors as the constraining conditions, the pollution export and flux coefficients were used to estimate the total pollution load. The results showed that the annual nonpoint source pollution loads of the total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) fluxes into the sea in the Jiaozhou Bay watershed were 1850 tons, 431 tons and 6632 tons, respectively. For TN, TP and COD, the contribution to the pollution source intensity ranked as follows: rural residents > livestock and poultry breeding > mariculture > land use > atmospheric deposition. Notably, rural residents and livestock and poultry breeding were the most important pollution sources. Based on this result, the emission characteristics of nonpoint pollution in bay areas and the associated effects on the condition of the aquatic environment were investigated to identify the critical sources of nonpoint pollution and propose measures for pollution control and optimization. This study provides a reference method for controlling the total amount of nonpoint source pollution and promoting the healthy development of the marine environment in bay areas.