Assessment Of Ecological Geochemical Effect On Sewage Irrigation Region In Shijiazhuang City

Sewaged-irrigation is very popular in the north of our country.Because the system of sewaged-irrigation is not healthiness,heavy metals are accumulated in every circumstance medium.The harm cased of has been attached importance to.The study chooses the sewaged-irrigation area of Shijiazhuang which is irrigated by sewage for a long time,and appraises the soil,underground water and human health.Regarding of soil quality,underground water quality and human incidence of diseases,we an get the conclusion as follow:(1)Cd,Cr,Hg,Pb and Za in the surface of sewaged-irdgation area,especially between 0～20cm are higher than those in inner,and there is a downward current near by Dongmingqu. Because eluviation of somewhat acid wastewater is downward distinctly,the quality of As is low in the area of sowaged-irdgation.(2)Evaluating by the soil environmental quality standards(GB 15618-1995),green food production environmental quality standards(NY/T391-2000) and soil background value of Shijiazhuang,we can conclud that exclude one sample the others are suitable for cultivating pollution-free crops,but has not suitable for cultivating green crops.(3)Near surface of sewaged-irrigation area are contaminated differently.The content of COD,volatilized hydroxybenzene,Pb,Cd,NO^?-N and NO^?-N is higher than those in area which is irrigated by clean water.The contaminated of As,Pb and Cd has been accumulated.The content has not exceed the underground water standardⅢ,but has exceed standardⅡ.The content of lead has exceed underground water standardⅡ.(4) Used the comparison method in epidemiology,we take an investigation about incidence of diseases in areas which are irrigated by sewage and clean water in Luan Country.The conclusion is that it is dearly that there is a distinct effect to human who live in areas which are irrigated by sewage and clean water.Compared with area which is irrigated by clean water,Entire cause of death mortality rate,and the death rate cased by Heart cerebrovascular disease,malignant tumor are higher.Compared with data in 1984,the incidence of a disease of malignancy is rising.(5) Sewaged irrigation has increased instability As content,exchangeable Cd,organic substance-bound,Fe-Mn oxide-bound,humic acid Cr and Fe-Mn oxide-bound Pb.So in the Sewaged irrigation areas the bio-availability of As,Cd,Cr,Pb has been increased.In the same time the Sewaged irrigation has increased the contents of As,Cd,Pb in the ground water.But the Sewaged irrigation has increased the stable Hg.