The Study On The Character Of Nutrient,Heavy Metal,As And Hg Content And Its Spatial Distribution In Daye Lake Sediment

Daye city,as a typical mining city,its ecological environment was damaged and the Daye Lake was polluted by mine development.In order to promote resource utilization of lake sediment for the vegetation restoration and accelerate the ecological remediation in mines and the lake management,the sediment in Daye Lake was sampled during the field work and tis nutrient,Cu,available Cu,Pb,Cd,As and Hg content was determined,and its spatial distribution was also analyzed in this study.The results showed as below.(1)The nutrient content and spatial distribution features in Daye Lake sediment1)The range of available content of N,P and K was 41～689、9～136 and 45～211 mg·kg-1,while the content of organic matter and total N.P,and K was 23.0～215.1、0.5～7.1、2.8～7.3、0.1～2.1g·kg-1,respectively.According to the classification criterion of soil nutrient used in 2nd national soil survey,the organic matter content in all samples was above the middle level and the abundant level was 96%,the available N and total N content was made up of 76%and 80%by above abundant level and the low level only counted up 8%and 16%,all available P content in samples was above middle level and the abundant level counted up 96%,while only 20%of the total P content was above abundant and 72%of which was low level,and 80%of available K was above middle level and only 36%of which was above abundant,but all total K content was at low level.This meant that sediment in Daye Lake was abundant of organic matter,N and P,but was lack of K,relatively.2)The variation trend of organic matter content decreased with the longitude and had no obvious rend with the variation of the latitude.The total P content fluctuated in a definite range with the variation of the longitude but it changed irregularly with the latitude.The trend of alkaline hydrolysis N,available P,available K,total N and total K content was not obvious with the change of latitude and longitude.(2)The content and spatial distribution characteristics of heavy metals in Daye Lake sediment1)The total copper,available copper,total lead and cadmium content in all samples in Daye Lake sediment range respectively was within the range of 500-3100,75-353,465～659.89 and 0～414 mg kg-1.According to the national soil environment quality standard(GB15618-1995),the total Cu and Cd content in all samples exceeded the grade Ⅲ,while only 16%of Pb content in samples exceeded.According to the effective copper content in soil classification and evaluation index,the available copper content was above very high level.This showed that the sediment in Daye Lake was seriously polluted by heavy metal,especially by Cu and Pb.So the removal and stabilization of Cd and Cu in sediment must be focused on in the process of sediment resource utilization in mine vegetation restoration.2)The total copper content increased with the longitude and decreased with the latitude.The available Cu content increased with latitude but had no obvious trend with the change of longitude.Total Pb content decreased with longitude,but had no obvious trend with the change of latitude.Total Cd content decreased sharply first and then went stably with longitude,and had no obvious trend with the change of latitude.(3)the daye lake sediment arsenic,mercury,and spatial distribution features:1)The total As and Hg content was within the range of 48～2812 and 0.1～6.7 mg·kg-1in all samples in Daye Lake sediment.All total As content and 44%of total Hg content in sediment exceeded the grade Ⅲ in national soil environment quality standard(GB15618-1995).This indicted that the sediment in Daye Lake was seriously polluted by As and it should be paid attention to in the resource use of sediment in mine vegetation restoration.2)The total As and Hg content decreased rapidly at beginning,and then went stably with the increase of longitude,but had no obvious regularity with the change latitude.(4)The relationship among the nutrient,heavy metals and As,Hg content:With the exceptions between the total K and organic matter,available N,total N,available P and total P,and between available K and organic matter,all nutrient index determined in this study had significant relationship between each other.There was a significant relationship between the total Cu and total K,between available Cu and available N,total N,available P,between total Pb and total N,K,P,and between total Cd and organic matter.The correlation of the total Hg content to organic matter,available N and P,the total N and P,the total As content to the total K,P,Pb and Cu,the total As and Hg to the total Cu,Pb and Cd was significant respectively.In summary,the sediment in Daye Lake can use as substrate in mine vegetation restoration in the light of nutrient content,but the K content should be increased.On the basis of pollutants content,the removal and stabilization of Cu,Cd and As must be emphasized.For the purpose of resource utilization of sediment in Daye Lake,vegetation restoration in mine and the management of Daye Lake,the consideration of the relationship between nutrients and pollutants and the integrated treatment of sediment was required urgently.