Study On The Nitrogen Of Non-point Source Pollution Of Shanzi Reservior In Fuzhou

Fuzhou Shanzi reservoir is the second water resource in Fuzhou. The reservoir directly impact on the water quality of public drinking water safety in Fuzhou. The detective results of these recent years showed: the eutrophication of Shanzi reservoir become serious day by day. The investigation date shows: the agricultural non-point pollution has been one of the main pollution to Fuzhou Shanzi reservoir.In order to study the characteristics on nitrogen losses in small watershed area in Shanzi reservoir, we monitored four rainfall runoff and the pollutant concentration from August 2007 to September 2007. On the basis of sampling monitoring in the field, we used the SWAT model to estimate the nitrogen load about Shanzi reservoir. At last, we got the conclusion as follows:1. The nitrogen concentrations in earlier rainfall were higher than those in the later rainfall. The changes of selected typical small watershed from maximum to minimum is pine bamboo,paddy fields,sweet potatoes.2. The land use pattern has significant impact on nitrogen loss, the sequence of pollutant concentration from maximum to minimum is paddy fields,sweet potatoes,pine bamboo. The major part of losses is in the form of NO₃^-N. The regression analysis results showed that polynomial relation existed between runoff and nitrogen loads, and the R² values of pine bamboo,paddy fields and sweet potatoes were 0.9607,0.9755 and 0.9834.3. Between three types of land used, the highest nitrogen content is from 5 cm to 10cm. There is a large amount of change before rain and after rain. The soil NO₃^-N accumulate in 5 cm to 10cm. The NH₄⁺-N absorption capacity of the typical land-use types in Shanzi reservoir from maximum to minimum is pine bamboo (2500 mg/kg), sweet potatoes (1250 mg/kg), paddy field (833 mg/kg); And the NO₃^- -N absorption capacity from maximum to minimum is pine bamboo (1476 mg/kg), sweet potatoes (1078 mg/kg), paddy field (973 mg/kg)4. The lecture also use the SWAT model to simulate the nitrogen output load from May 2007 to October 2007 in Shanzi reservoir. During this period the loss of nitrogen to 110.2t; August and September respectively output of the simulation period nitrogen load of 23.5% and 25.14%. The result shows that this period is the main events of the non-point source.