Characteristics And Risk Assessment Of Water Pollutant Of Nitrogen And Phosphorus In The Slope Chinese Herbal Medicine Planting Area

Danjiangkou reservoir is the water source of south-to-north water transfer project in China and the national water Ⅰ level reserves. The requirement of south-to-north water transfer project in Danjiangkou reservoir water quality is the national Class Ⅰ water quality of surface water. TP content of reservoir water quality must not exceed 0.02 mg·L-1, and TN content must not exceed 0.04 mg·L-1. But through the detection of Danjiangkou reservoir water quality, it was found that the water quality TN content is 1.46～1.60mg·L-1, which is 35 times standard of TN content beyond control. TP content is 0.02～0.05 mg·L-1. Through analysis of standard of composition, it was found that the main pollution source is the reservoir surrounding agricultural non-point source pollution, around 100, ten thousand mu of Chinese herbal medicine planting is the important source of nitrogen and phosphorus pollution. In this article, through more long time of field sampling analysis it is concluded that Chinese herbal medicine planting demonstration area spatial and temporal distribution of nitrogen and phosphorus; Using laboratory artificial simulation of rainfall device to analyze different rainfall intensity and fertilizer rate of two kinds of slope soil loss of nitrogen and phosphorus, organic matter, pH, etc; According to the simulated rainfall experiment data to construct two kinds of slope soil nitrogen and phosphorus loss model, using the validated area collect data on site, and to identify the area by using the index of nitrogen and phosphorus loss of nitrogen and phosphorus high risk areas, and compared two kinds of Chinese medicinal materials with the largest planting turmeric and the characteristics of nitrogen and phosphorus loss risk with a slope.Through the regular field sampling analysis of Chinese herbal medicine planting demonstration area of spatial and temporal distribution of nitrogen and phosphorus found that:(1) The Chinese herbal medicine planting demonstration zone soil TN, TP and general farmland soil organic matter were lower than average huazhong area 200.00 mg·kg-1,200.00 mg·kg-1 and 3.00%, soil fertility is low as a whole;(2) The spatial distribution of planting demonstration area of the regional soil TP and organic matter is relatively uniform, altitude, the contents of regional soil TN lower than area;(3) The rain flushing action of the soil TN migrated from high elevation to low elevation;(4) TN, TP in soil can’t directly determine organic matter content of soil.Through the simulated rainfall experiment study found:(1) Under the same fertilizer rate, with the increase of rainfall intensity, soil TN content decreased, soil slope runoff TN concentration decreased, slope surface runoff of TN loss increase, reduce leachate TN concentration, leachate of TN loss increased significantly;Soil TP is from the soil to the soil depth migration trend is more obvious, elevated soil slope runoff TP concentration, increase of slope runoff TP loss, reduce leachate TP concentration, leachate of TP loss increases significantly.(2) The loss of soil TN, TP and leakage than slope runoff erosion.(3) Under the same rainfall intensity, the increase of fertilizer rate twice, TN content in the soil, water quality TN concentrations increased 8 times;The TP content of surface soil in a substantial increase, water quality concentration of TP increased five times.(4) Fertilizer rate than the effect of rainfall intensity on soil nitrogen and phosphorus loss is bigger;Under the same fertilizer rate, should be a small amount of fertilizer for many times.(5) Other similar natural conditions, under the same rainfall intensity and fertilizer rate, the characteristics of slope of TN and TP loss than turmeric slope, considering the environmental pollution risk, we give preference to Chinese traditional medicine platycodon grandiflorum.According to the nitrogen and phosphorus loss model and risk assessment for the area found that:(1) The construction of nitrogen and phosphorus loss model through the actual test in the range of allowable error, the model can be used in Chinese herbal medicine planting of nitrogen and phosphorus loss estimation with a slope catchment areas.(2) Through the model that fertilizer rate and TN, TP, serious, and strong correlation between the fertilization rates by a great impact on the loss of nitrogen and phosphorus nutrients, rainfall intensity and TN, TP loss of relevance is poorer, less influence with the similar simulation experiment conclusion.(3) From the point of the whole area, the area the entire risk of nitrogen loss in low risk, low risk of nitrogen loss.P loss risk is given priority to with moderate risk, risk of phosphorus loss is higher.The whole area of phosphorus loss risk of nitrogen loss risk is much higher.Corn belt nitrogen and phosphorus loss at highest risk.To carry out the main forest slope the nitrogen and phosphorus pollution characteristics and risk assessment research, for Chinese herbal medicine planting on sloping lands surrounding the Danjiangkou reservoir are nitrogen and phosphorus pollution control and the south-to-north water transfer project, some reliable data reference of water quality safety and to ensure the security of water quality of main forest is of great significance.