Characteristics Of Soil Environmental System And Ecological Risk Assessment Of Heavy Metal Pollution In The Downstream Of Biliu River

There is a close relationship between soil environmental quality along the river and plant growth and development and human health,and it is of great significance for detecting river water quality and assessing the stability of the ecological environment along the river.In recent years,along with the rapid economic development in coastal areas and the increasing intensity of coastal wetlands,the pressure on environmental pollution is also increasing in the downstream of Biliu River.Based on this,the paper uses field tests and sampling,indoor X-ray fluorescence spectrometry data analysis,Pearson correlation analysis,and soil heavy metal pollution assessment methods to systematically study the environmental characteristics of soil and ecological risks of the heavy metal pollution soil in the downstream of the Biliu River.The main conclusions are:(1)According to the physical characteristics of the 0~20cm layer soil in the downstream of Biliu River,the average soil temperature is 23.75°C during September and October,which varied between 14.82~31.50°C;the clay particle accounted for 61.97% of the grain size,silt and sand at 18.03% and 20.00% respectively,the overall soil texture is clay.According to the chemical characteristics,the average soil pH is 7.13,which varied between5.42~8.06,and the soil pH is generally neutral;The salinization characteristics of the soil are significant.The average organic matter content is 1.73%,which varied between 0.4%~3.4%;the average conductivity is 2.83ms/cm,which varied between 0.05~9.79ms/cm;salt content the average value is 1.53 g/L,which varied between 0.02~5.40 g/L.(2)According to the contents of nutrient element of the 0-20 cm layer soil in the downstream of Biliu River,the K,Ca,Mg,Fe,Na,and Mn elements are all lower than the soil background values of Liaoning's and Chinese soil background values,and the Mg element is significantly lower.According to the content of soil heavy metals,the Zn,Cu,As,Cr,Pb,and Cd are all lower than Liaoning's and Chinese soil background values,and Ni is slightly higher than Liaoning's and Chinese soil background values.Therefore,the heavy metal content of Ni is excessive of the soil in the downstream of Biliu River.(3)Correlation analysis show that the content of nutrient elements P,Na,Mn,and Al are positively correlated with organic matter content(R=0.455~0.749,P<0.05,n=24)of soil in the downstream of Biliu River.The content of Na,Mg,Fe and Al are positive correlated with the electrical conductivity(R=0.523~0.883,P<0.01,n=24).The content of Cu ispositively correlated with salinity,electrical conductivity and organic matter(R=0.427~0.498,P<0.05,n=24).The contents of Zn is positive correlated with electrical conductivity and organic matter(R=0.638~0.836,P<0.01,n=24).It shows that part of the soil characteristics are important factors affecting the content of soil nutrient elements and the accumulation of heavy metal elements.(4)Based on the results of ecological risk assessment of Single pollution index,Geological accumulation index,and Nemero pollution index,the heavy metal Ni is slightly polluted of the surface soil in the downstream of Biliu River.The ecological risk assessment results based on Hakason ecological risk index showed that the potential ecological risk indexes of heavy metal As,Cd,Cr,Ni,Pb,Cu and Zn are 4.12,3.74,3.02,5.18,0.98,3.56 and 2.35,respectively indicate that the Ni element has potential ecological risk of pollution of the soil in the downstream of Biliu River;the comprehensive potential ecological risk index of the 7 heavy metal elements is 18.2,indicating that is slightly polluted of the soil in the downstream of Biliu River.