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Recognizing the loss of soil phosphorus characteristics of a region is to do the work of an important part of phosphorus control, prevention and treatment of non-point source pollution is also an important part. The construction of the Three Gorges Dam, the reservoir facing more and more serious environmental problems. Soil Erosion Research Three Gorges Reservoir and non-point source pollutants phosphorus loss characteristics of the reservoir area of ??agricultural production and environmental protection to provide a theoretical basis, but also for the establishment of a regional non-point source pollution in estimating model parameters to provide a reference. In this study, a small watershed in the Three Gorges Reservoir Area based sampling grid method through every 100m, collected a total of 118 soil samples 0-20cm 20-40cm and 15 cross-sectional sample. Analysis of its physical and chemical properties, soil characteristics for understanding the Fuling District, to provide a reference; and using the interpolation method to analyze the spatial distribution of watershed phosphorus, phosphorus loss identified high-risk areas; Based on Jane Creek by Fuling District Town Wangjiagou select countertops slope of 4 °, 9 ° and 17 ° layout experimental plot of land as the research object, its in April 2009 to November 2009 time rainfall and runoff observations for statistical analyzes three different slopes experimental plots at different rainfall conditions, soil sediment erosion, runoff water and phosphorus loss difference, explore the characteristics of soil phosphorus loss. The main conclusions are as follows: 1. Soil nutrient content and correlation with phosphorus Wangjiagou small watershed soil is neutral to slightly acidic majority. High organic matter content, are generally higher than 10gKg-1, and demonstrated as soil depth increases. Soil nitrogen content is higher, TN average 1.20gKg-1, the overwhelming majority of nitrogen is greater than 100 mgKg-1, both the performance with increasing soil depth decreases; soil total potassium content In between 6.8 ~ 22.7gkg-1 and K content ranged from 9.69 mgkg-1 ~ 173mgkg-1 between; total phosphorus content is relatively abundant, averaging 0.658 gkg-1, available phosphorus content in soil is greater than the cross-sectional surface soil kind, and both are large differences between each, topsoil phosphorus in 1.61mgkg-1 ~ 145mgkg-1, section like in 1.44mgkg-1 ~ 54.0mgkg-1, both coefficients of variation were 99.67% and 110.53%. And then the physicochemical properties of the correlation analysis, pH, total potassium and phosphorus showed a significant positive correlation; total nitrogen, available nitrogen, total phosphorus for phosphorus showed a significant positive correlation, pH, and available P was significantly negative correlation, potassium and phosphorus was a significant positive correlation. PH value reflects the popular phosphorus, total potassium,; nitrogen, nitrogen effects potassium and phosphorus also have some relevance. (2) the spatial variability of soil phosphorus content analysis from the relevant distance (variable range) look, soil total phosphorus and available phosphorus and related distances of 1550m 102m, soil sampling spacing greater than 100 m, showed that reflect their soil sample spacing Characteristics of spatial correlation, and can also determine the maximum sample spacing of 102m; view from the coefficient of determination, soil total phosphorus and available phosphorus determination coefficients were 0.941 and 0.257, the coefficient of determination of soil total phosphorus than soil available phosphorus, indicating that half variance model fitting degree of soil total phosphorus on soil phosphorus than fitting degree; soil total phosphorus and available phosphorus were semi-variance model spherical model and Gaussian model, the base variance 0.041 and 129, respectively, are positive , indicating the existence of the sampling error, a short distance variation, random and inherent variability caused by various positive base effect. Soil total phosphorus and available phosphorus nugget coefficients were 50.6% and 72.4%, between 25% -75%, indicating a moderate spatial correlation, which is composed of structural and stochastic factors together result. By kriging results, the spatial distribution of soil total phosphorus general trend: high levels of northwest and northeast, eastern and southern parts of the medium, the middle part is relatively low. Can be divided into three levels: soil total phosphorus content in the 0 ~ 0.58gkg-1; 0.58 ~ 0.84gkg-1; 0.84 ~ 1.73 gkg-1. Soil phosphorus distribution is higher northwest and east, middle and south are relatively low. Distribution can be divided into three levels: soil phosphorus content in 0 ~ 14.1mgkg-1; 14.1 ~ 32.7mgkg-1; 32.7 ~ 145 mgkg-1. Phosphorus maximum occurs in the northwest and east of the area, the minimum scattered in small watershed area middle and southwest, which may total phosphorus content and soil structure characteristics relevant, but also by soil parent material and soil type effects. This you can see, the central and southern watershed phosphorus loss are high-risk areas, the need for strict control, planting vegetation zones and the construction of a number of drainage ditches and reservoirs and other facilities. 3 different slopes sloping land on phosphorus loss in impact studies found that as the slope increases, the amount of runoff and sediment are increases, ie, 17 ° gt; 9 ° gt; 4 °. Total phosphorus runoff, water soluble phosphorus and particulate phosphorus concentration and flow volume change is also presented her husband with the increase of the slope of the trend, namely 17 ° gt; 9 ° gt; 4 °. Phosphorus Loss from morphological point of view, particulate phosphorus loss greater than the amount of water soluble phosphorus loss, indicating that particulate phosphorus is easier than the loss of water soluble phosphorus. In the same time period, the concentration of phosphorus runoff sediment, total phosphorus and available phosphorus changes are increasing as the slope showing a decreasing trend, ie 4 ° gt; 9 ° gt; 17 °, in which all Changes effective than phosphorus phosphorus obvious. The amount of sediment phosphorus loss of two showed 17 ° gt; 9 ° gt; 4 ° trend, showing the greater slope, the greater the amount of phosphorus loss. In the same rainfall and cell surface coverage, the loss of phosphorus and phosphorus volume trends similar to the first increase and then decrease, and finally stabilized. 4 different slopes sloping upland watershed level phosphorus loss estimates by April 17 to October 9 this time on the test cell phosphorus loss statistics, combined with the various watershed slope grade dry slope area, introduction of surface slope can be calculated area is 17 ° to the maximum amount of phosphorus loss, 103.83kg; mesa region 9 ° slope phosphorus loss amount 66.45kg; mesa area slope of 4 ° phosphorus loss amount 10.89kg. And this time, including May 13 to July 2 this time as phosphorus loss peak, slope greater than 15 ° of phosphorus loss risk areas, need special control; while 6 ° ~ 15 ° of phosphorus the loss of prime crisis area, but also requires special processing, to control phosphorus emissions. The gradient of 0 ° ~ 6 ° can simply improve farming methods and appropriate land under heavier hedgerow, you can control phosphorus losses. 5 Different rainfall impact study on phosphorus loss with different rainfall runoff and sediment, and phosphorus runoff and sediment in relation to derive the impact of rainfall on phosphorus loss characteristics. The results found that different experimental plot rainfall runoff and sediment volume effects are as slope increases, ie 17 ° gt; 9 ° gt; 4 °. Rainfall and runoff correlation coefficient greater the greater the slope, ie 17 ° gt; 9 ° gt; 4 °; while rainfall and sediment loss relationship is the opposite, the smaller the slope, the stronger the correlation . For total phosphorus in runoff water and water soluble phosphorus concentration and rainfall relationship is concerned, only the slope of 4 ° of the cell there is a significant correlation between the two phosphorus concentration values ??single correlation coefficient was R2 = 0.2659,0.2789, and 9 ° and 17 ° of the district have not reached correlation; pair of particulate phosphorus, the slope of 4 ° and 9 ° of the cell concentrations in runoff water and rainfall relationships are reached a significant, correlation coefficients were R2 = 0.2986,0.2674. The three kinds of phosphorus concentrations in runoff water is manifested as first decreases, then increases again is stabilized. Slope of 4 °, 9 ° and 17 ° of the experimental plot runoff water total phosphorus, soluble and particulate phosphorus losses between the amount of rainfall are highly significant correlation. The slope of 9 °, the rainfall and total phosphorus, soluble phosphorus and particulate phosphorus minimum correlation coefficients were R2 = 0.6465,0.636 and 0.6429. Rainfall during this time is the first increases and then decreases, then increases slightly, but did not reach the high point of the original. The three kinds of phosphorus in runoff water is expressed as the total loss of the first decreases and then increases again is stabilized phosphorus runoff sediment concentration, total phosphorus losses from changes in rainfall are as increase while showing an increasing trend, and finally stabilized, and then finally with the rainfall increases with increasing concentration values ??are not. Slope of 4 °, 9 ° and 17 ° of the experimental plot of total phosphorus in sediment and phosphorus loss on total rainfall have reached a very significant correlation, indicating rainfall for total phosphorus and total phosphorus loss volume relationship very close, we can say the loss of rainfall determines the amount of phosphorus. Slope was 4 °, 9 ° and 17 ° of the experimental plot of total phosphorus loss for all rainfall correlation coefficient was R2 = 0.7591,0.6918 and 0.6981, reached a very significant correlation. Description rainfall total loss of the whole amount of phosphorus a very close relationship, we can say the loss of rainfall determines the amount of phosphorus. 6 engineering measures for phosphorus retention effect through September 20, 2008 to November 19, 2009 in the Three Gorges Reservoir Area of ??Fuling Wangjiagou important watershed drains and terraced areas were the focus of reservoirs, etc. track and monitor the entire projected area of ??engineering measures of terracing phosphorus retention capacity of 1.34kg/hm2. Can be drawn through engineering measures can be effectively controlled watershed phosphorus loss.
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