Evaluation Of Soil Nutrient And Heavy Metal Pollution In The Middle And Upper Reaches Of Chishui River

In recent years,the ecosystem service function of Chishui River Basin has a trend of decline.It is critical that soil nutrient loss leads to water eutrophication and the heavy metal pollution problem is also serious,which heavily threatens the health of ecosystem service function of Chishui River Basin,but also affects the environment of the place of production of famous liquor.In this paper,the natural slope of the San Yuan Village in the Wuma Town,Renhuai City,in the upper reaches of the Chishui River,was used to analyze the state of soil nutrient loss and heavy metal pollution of the soil by sampling,determinating and analyzing the surface soil of different slope and the following main conclusions:1.The content of total nitrogen,total phosphorus and organic matter in the soil of the village of Wuma town,Sanyuan Village is relatively abundant,and the difference of land use is not significant.The total nitrogen and organic matter are influenced by human activities.The soil erosion is slight,and less soil organic matter loss and total phosphorus loss is conductive soil organic matter,total nitrogen and total phosphorus accumulation and maintenance.However,the total potassium content is really low.2.The results of Fuzzy comprehensive evaluation of soil nutrient showed that the soil nutrient grade of Sanyuan Village in the Wuma Town could be classified as three levels,and the soil nutrient was at a high level.However,the above analysis is based on data of the soil particle,of which diameter is below 2mm.A large number of gravel in the soil measurements showed that the average gravel content was 43% by weight,which seriously affected the ability of soil tillage and also the ability of water retention and fertilizer capacity of the soil.3.The contents of Hg,Cu,Zn,Ni and Cd in the soil of Wuma Town,Sanyuan Village were high.Cu and Cd contents were affected by human activities more seriously,while other heavy metal elements' effects were less compared with Cu and Cd.The degree of Cu and Hg enrichment is high,while the variation range of other heavy metal elements regional context is small.Part of the sample has shown the characteristics which is caused by varying degrees of heavy metal pollution.It will pose a threat to soil environmental quality and quality of agricultural products in the region.4.The evaluating results of comprehensive potential ecological risk index show that the comprehensive ecological risk of the heavy metals in the village of Sanyuan Village is slight and it is relatively safe.The result of the improved fuzzy comprehensive evaluation model shows that the four sampling points are slightly polluted(grade ?),20 sampling points are really good(grade ?),and there is no moderately polluted point.The evaluating results of heavy metals soil pollution in Wuma Town,Sanyuan village using the improved fuzzy comprehensive evaluation model are consistent with the results of the assessment of the potential ecological risk index.The soil of the Sanyuan Village is in a safe state overall.5.In general,the soil erosion of Sanyuan Village is mild,and the rocky desertification is light,and also the soil and water conservation is good.Besides,the nutrient content of the soil is at a high level,but the gravel ratio is too high to lead to poor soil quality,heavy metal is slightly polluted and the soil is in a safe state.However,there was still a significant gap compared with the soil quality of cultivated land and woodland in the East and South of our country.For example,the phosphorus content was seriously low,and the pollution of Cu,Hg,Ni and Cd was relatively serious,which requires more for soil and water conservation and pollution Prevention in this region hereafter.