Seasonal and vertical distribution characteristics of nitrogen and phosphorus content in the sediment and overlying water of Caohai in Guizhou

To promote the sustainable development of plateau wetland of Caohai in Guizhou, to improve the environment of Caohai, to restore the function of wetland of reserve area in Caohai, studied the seasonal and vertical distribution characteristics of nitrogen and phosphorus in sediment and overlying water in the wet period and dry period, and evaluated the water quality in Caohai according to the standard of surface water environmental quality. The results showed that, the spatial variability of TN and TP in sediment of the two periods was moderate degree. The spatial characteristics of TN in sediment in abundant water period was S area>N area>E area, the content of alkali-hydrolyzed N of sediment in high and low water periods was S area >E area >N area; the distribution characteristics of available phosphorus in sediment in wet period was E area>S area>N area, the distribution characteristics of available phosphorus in sediment in dry period was E area>N area>S area. The content of TN and alkali-hydrolyzed nitrogen in sediment increased gradually from south to north when in wet and dry water periods, increased gradually form west to east. The value of numerical indicators of east water district in Caohai was high than those of the west water districting. The pollution source of sediment and overlying water was mainly the farmland fertilizer in Caohai surrounding, the generated wastes of breeding of livestock and poultry in surrounding villages and living sewage. Attention should be paid to limit the emissions of waste and wastewater in the agricultural production.