Occurrence Modes And Transportation Characteristics Of Non-point Source Pollutants In Muyang Watershed, Yunnan

Non-point source pollution had become one of the biggest problems of water pollution in the worldwide. Non-point source pollutants come from the agricultural chemicals in pedosphere, so its formation, transport process was essentially pollutants in rainfall or under the condition of drainage from the pedosphere to the other circles, especially to the hydrosphere. The transport of pollutants in soil was mainly generated from surface runoff. This paper studied the Muyang watershed which is mainly based on traditional agricultural in DianChi watershed. This study focus on the mode of occurrence and transport rules of pollutants; the relations between the surface source pollutant components and contaminant particles size; the determination of the non-point source pollution load based on the pollutants input-output system. The main conclusions are as follows:(1) Muyang watershed was a typical agricultural area which has great potential of non-point source pollution component output. The watershed had high soil nutrient content. There was a minor difference of soil nutrient content among up, middle and down reaches of Muyang watershed. Because of agricultural planting, the soil nutrient content tended to be stable.(2) The transport process of pollutants soil indicates that the pollutants content can be significantly reduced in30minutes then gradually slow down and finally established the equilibrium8hours later.50%of the particulate pollutants in river sediment after8hours, the remaining particulate pollutants continue to follow the migration of river. After8hours settlement, the<0.002mm particulate pollutants continued transport in the river.<0.002mm particle size was the main pollutant migration in the range of particulate pollutants. No matter in the soil solution or in the river runoff, the transport law wsa the same.So silt arrester, settlement and Filtering method can be applied in water pollution treatment in Muyang watershed.(3) The water of Muyang watershed was typical headwater area water quality. Non-point source pollution had decisive effect in concentration of pollutants and transport quantity in the watershed. The each months of pollutant and rate of flow variation was the same. The flow and concentration of pollutant had positively related. With the reduction of rainfall in2011, river flow was increasing; content of pollutants compared to the same period was lower in2010. The result showed that the rain washed had influence in water. The river water was Ⅱ class water quality.(4) Heavy rain with the same time and different section water quality monitoring results showed that, the pollutant content was gradually increased, pollutants gradually accumulated along the way; the different section water quality monitoring results showed that, There existed obvious different sections of the pollutant concentration by field with heavy rains streak characteristics of decay, the first heavy rain on river pollution around the scour than other rainstorm.(5) First rainstorm runoff pollutant concentration and greater correlation, as rainfall increased, the remaining rainstorm runoff pollutant concentration and of little relevance. A rainstorm during the pollutant concentrations in the three sections of the changes and correlation degree of fluctuation water, mild, and river catchment area size.Output of pollutants runoff volume and with good correlation, indicating whether or not the size scale, non-point source pollution is mainly a runoff scouring surface forming process of pollution.