| Our country is one of the countries with the richest coal resources in the world.Long-term coal mining activities have led to changes in surface morphology,climate,biology and other ecological factors.Huainan is an important coal base in my country.Coal mining has led to the formation of a large area of underground mined-out areas.Because Huainan is located in an area with high phreatic levels,large areas of water have been generated in the area of surface subsidence,forming a coal mining subsidence area..The original terrestrial ecosystem was transformed into a wetland ecosystem after the formation of the stagnant area.Therefore,it is of practical significance to study the physical and chemical properties of soil,sediment and overlying water,and the time and space distribution characteristics of heavy metals in subsided wetlands,and to construct an ecosystem health evaluation system.This article takes the Digou National Wetland Park as the main body of the subsidence area as the research object,collects 23 soil samples,35 sediment samples and 35 overlying water samples,analyzes the physical and chemical properties,heavy metal content.The health status of the land and water ecosystems of the wetland park was evaluated,and the results showed that:(a)The overlying water quality of Digou Wetland Park is greatly affected by nitrogen and dissolved oxygen.Based on the results of the comprehensive pollution index,Nemeiro index and comprehensive nutritional status index method,the water quality of Digou Wetland Park shows severe pollution levels,with the worst water quality in winter and spring,followed by summer and autumn.(b)The soil texture of Digou Wetland Park is mainly heavy loam and light clay.The level of soil nutrients is the highest in total nitrogen,followed by total potassium,organic matter and total phosphorus.The spatial distribution characteristics are higher in the central and eastern regions than in the western regions.The spatial difference of soil enzyme activity is small,and the overall distribution is even.The comprehensive evaluation results of soil nutrients show that the soil fertility of the land area of Digou Wetland Park is above the medium level.The soil heavy metals in Digou Wetland Park are dominated by minor ecological risks.The pollution levels are Cd,As,Cu,Pb,Zn in order from high to low.Among them,As and Cd are the main pollutants.The overall spatial distribution is higher in the middle than in the east.Department area.(c)The sediment particle composition of Digou Wetland Park is mainly silt.The total phosphorus pollution is relatively serious,mainly imported from external sources.The total phosphorus of the sediment is mainly inorganic phosphorus,and the phosphorus form shows the characteristic that the content of acid-soluble phosphorus is lower than that of alkali-soluble phosphorus.The content of Cu,As,Cd,and Pb in the sediments of the wetland park is higher than the background value,showing that the central part is higher than the eastern part.The heavy metals in the sediments of Digou Wetland Park are at a slight ecological risk level.The pollution levels are Cd,As,Cu,Pb,Zn in descending order,and the main pollutants are Cd and As.(d)The comprehensive index of health of the terrestrial ecosystem of Digou Wetland Park is 0.311,which belongs to the poor(category IV)level.Among them,the sampling sites of disease,poor,and medium levels account for 4.4%,78.2%,and 17.4%,respectively.The spatial distribution shows the characteristics of uniform overall distribution.The water ecosystem health index is 0.62,which belongs to the sub-health(Class Ⅱ)level.Among them,there is one sampling point for the poor and disease levels.On the whole,the water ecosystem health status is inferior to the eastern and western regions.Among them,As Cd and Cd are two indicators that have a greater impact on the health of water ecosystems. |
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