The Nutrient Status And Evaluations Of Eastern Dongting Lake Wetland Soil

Eastern Dongting Lake Wetland is the natural protective barrier of Eastern Dongting Lake. The natural environment of Eastern Dongting Lake Wetland is superior, it’s not only a national wetland reserve but also an important agricultural region. With the rapid development of urbanization and frequent industrial and agricultural activities in the lake district, the impact of human activities increases significantly which leads to the degradation of wetland ecosystem. In this paper, the spatial distribution of 7 nutrient elements including organic matter(SOM), total nitrogen(TSN), total phosphorus(TSP), total potassium(TSK), available nitrogen(A-N), Olsen phosphorus(Olsen-P), available potassium(A-K)is analyzed as well as the eco-metering feature of carbon(TOC), nitrogen(TSN) and phosphorus(TSP). Evaluations are made on the soil nutrient levels and the pollution levels of carbon, nitrogen and phosphorus, which provides scientific management and ecological restoration reference for the Eastern Dongting Lake wetland soil. The main conclusions are as follows:(1) In addition to TSK, the average nutrient content of wetland surface soil is higher than that in deep soil. The linear correlation coefficients between A-N and TSN, Olsen-P and TSP are higher which indicates that the supply level of Olsen-P and A-N was greatlyinfluenced by the content of TSN and TSP in soil. While the linear correlation coefficient among A-K and TSK, SOM is lower, indicating that A-K was less affected by TSK and SOM.(2) The C: N, C: P and N: P of the wetland soil showed a decrease with the increase of soil depth, but the difference was not significant.With the soil depth increasing, the variation coefficient of C:N, C: P and N: P increases. The horizontal distribution trend of C: P, N: P in two soil layers is similar, while C:N is on the contrary. The C: N of wetland soil is similar to the average level of China soil, while C: P, N: P is overall far lower than the average level of China soil.(3) According to the soil nutrient grading, a evaluation of surface soil nutrient was made, it showed that SOM, TSN, A-N, A-K were the limiting factors of soil nutrient. TSP, Olsen-P levels were higher and TSK is rich in content. Principal component analysis showed that: The soil nutrient status of Luhu Reed area and Yueyang area are best, while Chenglingji Port is the worst. Fuzzy evaluation results showed that the soil nutrients status of Yueyang area is best, while Tuanzhou Farm and Chenglingji Port are at a low level.(4) Single factor evaluation including TOC, TSN, TSP showed that:TOC low-level pollution index is less than 1, while TSN, TSP low-level pollution index are 1.47 and 1.08. Evaluation results of organic nitrogen,organic index assessment and integrated pollution index are consistent, 3kinds of evaluation all show that he contamination levels of TOC, TSN,TSP were atⅡgrade level, which indicates that Eastern Dongting Lake Wetland soil is at a relatively clean state.