Study On The Forms Of Heavy Metals Cu/Cd Under Different Soil Conditions

The accuracy of Tessier method and BCR method for the determination of heavy metals in soils was evaluated by the amount of heavy metal Cu / Cd absorbed by hyperaccumulators.The results showed that the error between the effective content measured by BCR and the actual absorption of plants was between 18.3% ~ 54.7% with an average of 31.9%.The error between the effective content measured by Tessier method and the actual absorption of plants was 3.1% ~ 10.4%,with an average of 6.9%.Therefore,the Tessier method is a more accurate method for the determination of the effective content of heavy metals in soil.Under different soil pH,soil organic matter content and soil texture,the effective content of Cu and Cd with time were studied.According to the assessment results,the effective content was measured by Tessier method and it is also called the exchangeable content.The results showed that after the Cu and Cd were added into the soil,it took a long time for them to be adsorbed and fixed by the soil and entered into a stable state.The time required for the stabilization ranged from 32 to 56 days and the average stable time was about 45 days.pH has a significant effect on the exchangeable content.In general,the alkaline environment could significantly inhibit the bioavailability of Cu / Cd and the acidic environment would enhance the bioavailability of Cu/Cd.The content of different organic matter had a significant effect on the exchangeable content,with the increase of soil organic matter content,the content of Cu / Cd exchangeable soil was significantly reduced,so adding organic fertilizer to soil could effectively treat Cu / Cd contaminated soil;Different soil texture has a significant effect on the exchangeable content.The stronger the soil viscosity,the lower the Cu / Cd exchangeable content in the soil.Therefore,the proportion of clay in the soil can be increased by agronomic measures to improve the Cu/ Cd Pollution Status of Polluted Soil.