Effects Of Red Mud Addition On Calcareous Soil Aggregate Enrichment Of Cu And Cd

Red mud is an inexpensive and effective material available for the in situ treatment of soil contaminated with heavy metals.In order to investigate the internal mechanism involved,a detailed analysis of the effects of red mud was carried out.The effect of red mud treatment on the soil physical chemistry property,distribution of soil aggregate,concentrations of Cu,Cd in size fraction and concentrations of Cu,Cd in corn was evaluated.Through compared the enrichment characteristics of heavy metals in size fractions under different proportion of red mud treatments,explore the effect of red mud on the migration regularity of heavy metals in size fractions.On this basis,analysis the remediation effect of red mud on contaminated soil,to provides the basis for the large-scale application on agricultural soil.The main results were as follows:1?The soil pH went up with the increase of red mud addition.When the addition of red mud was 5%,the soil pH was increased 0.84 compared with the blank control group.And red mud has a long-term affection of improving the soil pH.In addition,the red mud treatment also improved available kalium in soil.But,the red mud treatment had no obvious influence on available phosphorus and organic matter in soil,they were present certain regularity with the passage of maize growth period,which was related to soil environmental changed.2?Red mud addition and corn combined contributed to the aggregation of soil particles,accelerated the small size fractions became the larger size fractions,and the content of organic carbon in large size fraction is higher than small size fraction.The treatment of red mud could effectively reduce the concentration of available Cu in agricultural soil,especially reduce the concentration of available Cu in T2 size fraction(the fractions with size range of0.02 ~ 0.25 mm).Therefore,red mud treatment not only had obvious influence on the composition of size fraction and content of organic carbon,but also had influence on the concentration of available Cu in agricultural soil aggregate.3?The treatment of red mud could effectively reduce the concentration of available Cd in agricultural soil,when the addition of red mud was 5%,the concentration of available Cd decreased 51.48% compared with the blank control group.The concentration of available Cdin T3(the fractions with size range of 0.002~0.02 mm)and T4 size fraction(the fractions with size less than 0.002mm)were higher than other size fraction,the enrichment coefficient of available Cd in T3 and T4 size fraction were 1.24 and 1.03 respectively.Moreover,there were significant correlation between the concentration of available Cd and organic carbon in the same size fraction under red mud treatment.4?The concentration of Cu?Cd in each part of corn had significantly different,the Cu content in corn from high to low in the order:leaf > root > stem > fruit,and the Cd content in corn from high to low in the order: root > leaf > stem > fruit.The treatment of red mud could effectively reduce the concentration of available Cu?Cd in corn leaf,when the addition of red mud was 5%,the concentration of available Cu?Cd decreased 30.89% and 48.36% compared with the blank control group respectively.In addition,the content of Cd in corn root was higher than the available Cd in soil,it showed that corn root had rich collection about Cd.