Potential Risk Assessment And Limit Value Study For Cadmium In The Soil-Rice System Of Wucheng In Jinhua City

Cadmium,as a strong physiological toxicity element,has been widespread concern because it can destroy the enzyme system of the liver and kidney organs and increase the risk of cancer.Soil is mainly source for cadmium in rice,thus the evaluation of soil quality is of great significance.The current soil environmental quality standards of China was promulgated in 1995,the official release of the standard have unified national soil environmental quality standards for soil pollution assessment of china and provided a scientific basis for land management and soil pollution remediation.However,with the deepening of soil environmental quality research,the standards have highlighted more and more problems,so that it can not meet the demand of current land manage.In this paper,the Wucheng District of Jinhua City was selected as the research object.Based on the study on the migration and transformation of cadmium in the soil-rice system and the prediction model,the effect of the actual field model and the combined model of actual field and pot experiment was compared.The limit value of cadmium in the study area was reconstructed and the pollution evaluation was carried out.The main conclusions of this paper are as follows:Using the secondary limit value of cadmium in the current soil quality standard as the reference value,the spatial risk assessment of cadmium single factor in the study area is different from that of rice cadmium health risk assessment,which indicates that the Soil environmental quality guidelines/standards?GB151618-1995?is not adapted for soil risk assessment the study area;The results showed that the enrichment coefficients of cadmium in different organs of rice were in the order of root>stem>leaf>seed;The correlation between soil and rice in pot experiment is stronger,though the correlation between the various fields of rice in actual field is more relevant;By comparing the two types of prediction models established in the study area,it is found that the combined model of actual field and pot experiment is better than the actual field model,and the computational limit value of Cd production in the study area is 0.257mg·kg^-1;The pollution evaluation of the basic farmland data shows that there is pollution in the study area Of the plaque area of the total area of 17.72%,of which Yangbu Town and Luobu town south,Tangxi town on the west and south side,Langya town exist many contaminated areas;Southwest Research area due to lower the pH,should be avoided planting rice,rice cultivation mainly be conventional.