Study on the impact factors of nitrogen flux into the ocean in critical source areas-The case of Xiaoqing River Basin

This study takes the Xiaoqing River Basin as the research object, and uses the XGBoost model and SHAP algorithm to quantify the contribution of 10 factors such as meteorology, hydrology and nitrogen emission intensity to the total nitrogen flux into the sea in key source areas. The results show that rainfall is the dominant factor driving the flux of total nitrogen into the sea in the key source area, and its high eigenvalue is positively driving the flux. The contribution of livestock and poultry manure and rural domestic sewage in the sub-basins dominated by non-point sources is obvious ; the contribution of point source emission is prominent in the sub-watershed dominated by point source.