Application Research On Cadmium Contaminated Rice Farmland For Stabilization And Remediation

Soil and rice contaminated with Cadmium were studied in this paper.In order to reduce the content of Cd in rice,the technical route of applying soil conditioner was chosen through plot test and expanded test.Six kinds of soil conditioners(F1 Bentonite Iron + Biochar,F2 Sepiolite + Lime + biochar,F3 Humic acid potassium + Bentonite + lime,F4 Maifan stone + Iron + Biochar,F5 Humic acid potassium + biochar + Lime F6 Sepiolite + Humic acid potassium + Lime)were selected in the research.The best performing product was selected and applied to an expanded test.The cost analysis and on-site management experience for large-scale third party governance were provided from the test.Plot experiment showed that soil pH,organic matter and cation exchange capacity were negatively correlated with Cd in rice.Effective Cd in soil was positively correlated with total Cd in rice.It is feasible to use soil conditioner to reduce Cd in rice.Comparative experiments of 6 kinds of soil conditioners showed that the F4 showed better from reduction rate of Cd,soil pH change,output of rice.The suitable dosage is 150kg/Mu,the largest decline was 33.96%,rice Cd reduction was 49.85%.The content of Cd in rice is 0.168mg/kg and less than the "National Food Safety Standards of Contaminants in Food"(GB2762-2017)of Cd 0.2mg/kg?The field test based on plot test shows that:The physicochemical properties and the effects of Cd in rice were basically coincident between plot test and expanded test.F4 was greatly impact on strong acidic soil pH by 0.71.The available Cd in weak acidic soil was decline obviously and reached 29.09%.The reducing from high to low are: weak acidic soil(76.63%)> strong acidic soil(42.45%)> alkaline soil(35.33%).Application of data showed that the foundation of soil conditioner F4 of rice Cd decreased significantly.The average rice Cd decreasing rate was consistent with the plot test and expanded test.It was 52.85% and the overall compliance rate was 73.33%.From the soil pH and effective Cd,it was better the application of soil conditioner in tillering stage than that base fertilize.The application of soil conditioner before soil tillage could reduce the content of Cd in rice.By popularizing and applying,The mechanical spreader soil conditioner mixed with the soil was well-distributed than artificial and the cost is lower.Training,publicity,supervision,management and the sample backup should be fully arranged in large-scale application management.