府河下游典型村庄汛期面源污染过程与输出特征OACHSSCD

Village surface runoff is one of the important sources of pollution in the surrounding rivers of the village.In order to understand the pollution characteristics of rainfall runoff in ＂ open-type＂ villages without centralized drainage outlet,a high-frequency monitoring of rainfall events was conducted in Baizhuang Village,Anxin County,downstream of the Fuhe watershed.The dynamic emission patterns of nitrogen and phosphorus pollutants from the courtyards and the west outflow of the village under different rainfall conditions,as well as the initial flushing effect,and their relationship with rainfall characteristics were analyzed.The results showed that under different rainfall conditions,the concentrations of pollutants in the runoff from the courtyards and the west of the village outlet reached their maximum values at the beginning of the rainfall and then gradually decreased with the duration of the rainfall.The average concentration of total nitrogen at the outlet of the west of the village decreased gradually with the increase in rainfall intensity,it was 13.18 mg/L under light rain conditions,mainly due to the dilution effect of rainfall.The total nitrogen concentration at the outflow of the courtyard reached the highest level of 9.87 mg/L under heavy rain conditions.The average total phosphorus concentration at the outflow of the village west and the courtyard reached the highest level under moderate rain conditions.The pollution load is mainly influenced by rainfall and pollutant concentration.The total phosphorus load at the village west outlet and the courtyard outlet was the highest during moderate rainfall events.The village west outlet and the courtyard outlet respectively washed away an average of 36.92 kg and 0.26 kg of total phosphorus.Under the four rainfall conditions of light rain,moderate rain,heavy rain and torrential rain,the initial erosion effect of the outlet in the west of the village was greater than that of the courtyard.Especially under the conditions of light and moderate rain,the degree of pollutant erosion at the outlets in the west of the village and the courtyard was in the following order:total suspended solids＞total phosphorus＞total nitrogen.Under different rainfall conditions,the village surface runoff was mainly composed of nitrogen and phosphorus pollutants,and was mainly affected by rainfall volume during the flood season.Therefore,effective interception of the initial village surface runoff can be carried out under different rainfall conditions to reduce the input of nitrogen and phosphorus into surface water.