Study On The Remediation Technology Of Contaminated Farmland Soil By Cd In Mining Area Of Tongguan In Shaanxi Province

With the rapid development of industrial and agricultural economy and ever-increasing consumption of mineral resources, mining leads to a growing problem of soils contaminated by heavy metal, which attracts more and more extensive attention. Taking farmland contaminated by Cd nearby goldfield of Tongguan in Shaanxi province as research project and wheat as indicator, this paper conducts engineering remediational technology outdoor and potting indoor, and then assess the efficiency of both remediational technology through analyzing Cd content in different organs of wheat and its variation, and Cd content in soil before and after different remediational measure, in order to provide scientific evidence and conference for remediation of regional farmland contaminated by Cd, which is based on the summary of soil contaminated by heavy metal and remediational technology at home and abroad. Besides, propose a plan about experiment on combined remediational technology of contaminated farmland by Cd which is based on the research of this paper. The specific results are as follows:1. The treatment of different depth of soil-turned significantly increase the output and quality of wheat among engineering measure outdoor. The treatment of 80cm-turned soil has the best effect than the others and its output per mu of wheat reaches 518.4kg, which has a growth of 84.2% compared with the control, meanwhile, under the treatment of 80cm-turned soil and 40cm-turned soil, both of Cd content in grain reach the clean level.2. The treatment of different depth of soil-turned significantly reduce Cd content both in different organs of wheat and soil compared with the control. Cd content in ground part of wheat reduces by 48.84% in the treatment of 80cm-turned soil compared with the control and Cd content in root reduced by 61.24%, while Cd content in ground part of wheat reduces by 31.78% in the treatment of 40cm-turned soil compared with the control and Cd content in root reduced by 51.94%. The order of efficiency of different depth of soil-turned treatment on reducing Cd content in soil is 80cm-turned soil>40cm-turned soil>control.3.Applying different dose of amendments(K2HPO4, chicken manure and Na2S) promote the growth of wheat, increase the output of wheat, and reduce Cd content in different organs(ground part, underground part) of wheat. Under the treatment of high-dose chicken manure, increasing amplitude of grain weight reaches the highest. While under the treatment of chicken manure and Na2 S, Cd content in both grain of wheat reaches the National Food Hygiene Standards(GB2715-2005, Cd≤0.1mg/kg), and Cd content in grain has the biggest drop by 73% under the treatment of high-dose Na2 S. Under the treatment of 24g/kg chicken manure, transfer coefficient is the minimum.4. Available Cd content in soil in different treatment presents the decreasing trend with the increasing dose of amendments. Under the treatment of high-dose chicken manure, decreasing amplitude is the biggest and reaches the minimal 0.44 mg/kg. While under the treatment of 4g/kg K2HPO4, increasing amplitude of soil p H is the biggest and reaches 8.38. The order of efficiency of amendments on remediation is Na2S﹥chicken manure﹥K2HPO4.5. This paper propose a scheme of combined remediation technology for local farmland contaminated by heavy metal. Considering different irrigational conditions and different crops(grain, leaf vegetable), the scheme combines engineering and chemical remediational technology and the specific experiment and research will start in next phase of work.