Research On Adsorption-desorption Characteristic And Loss Of Soil Phosphorus Under Different Land-use Pattern In The Typical Areas In Dianchi Basin

Dianchi has become one of the most serious eutrophicated lakes. In recent years, local and state government have invested a lot to control pollution of Dianchi. With the implementation of quick and mature technology of point source pollution control projects, the trend of deterioration of Dianchi water quality has been controlled. However, the characterization of Dianchi eutrophication has not been improved significantly. One of the main reasons for water entrophication is phosphorus pollution, and non-point source and fertilization are closely related, but little research has been done on the adsorption and desorption of soil phosphorus. comes from non-point source is an important source of TP into the lake.Based on the Dianchi lake data and the field survey,130sample points were selected in Dianchi basin area for understanding basin-wide phosphorus distribution pattern and the characteristics of the soil phosphors desorption and adsorption.17of130samples point were selected to detect available phosphorus, dissolved phosphorus, phosphorus analytic experiment. Meanwhile, dynamic modeling experiments were performed for soil selected from different planting-life greenhouse. The results showed that:(1) The total phosphorus (TP) contents of the samples varied from0.137～8.434g/kg, the average was1.330g/kg. The TP content relatively high in Dianchi lake basin, the order of TP was phosphate rock zone> removal zone in lakeside> dam ground> greenhouse> slope>woodland.(2)The adsorption isothermal of soil phosphorus showed that:The model can achieve the better fitting effect The Langumuir equation can achieve the better fitting for phosphorus adsorption characteristics of in Dianchi lake basin. The amount of easily desorption phosphorus:phosphate rock zone> removal zone in lakeside> greenhouse> slope> dam ground> woodland. The maximum phosphorus adsorption capacity:phosphate rock zone> remove zone in lakeside、slope> greenhouse> dam ground> woodland. K:Woodland> dam ground> greenhouse> slope> removal zone in lakeside> phosphate rock zone. Maximum buffer capacity:dam ground> woodland> greenhouse> slope> phosphate rock> removal zone in lakeside (3) Phosphorus desorption experiment showed that:the dissolution of soil phosphate brought into equilibrium in60minutes. In the early30minutes, the dissolution rate was faster, and then the curve slowed down.6types of soil dissolved total phosphorus in equilibrium concentration swere in the range of0.06560-9.5225mg/kg, the average was4.000mg/kg.(4) Phosphorus desorption-adsorption equilibrium point experiment showed that the mass concentration of desorption-adsorption equilibrium in different land-use were significant similar. All the soil phosphorus adsorption desorption equilibrium points were0.0008-0.0479mg/L.(5) The dynamic modeling experiment showed that no significant relationship was found between the phosphorus content and soil depth for3types of different planting-life,. The first dissolution phosphorus was significantly greater than second dissolved phosphorus.Based on above results, we can conclude that soil TP content were generally higher in Dianchi basin. Phosphate rock zone and removal zone in lakeside have the highest TP content, maximum phosphorus adsorption capacity, and easily desorption phosphorus content. Woodland has the lowest TP content, maximum phosphorus adsorption capacity, and easily desorption phosphorus content. Dam ground, greenhouse, slope ranged between the two cases. The higher soil TP, the higher available phosphorus and easily desorption of phosphorus are, the smaller the maximum buffering capacity is. Therefore, controlling the amount of fertilization is one of the most critical measurements in the transporting control of phosphorus in non-point source pollution.