The Soil Cadmium Bioavailability And Ecological Risk Assessment In The Soil Of Hubei Province

Excessive amounts of heavy metals in the soil can cause harm to the environment and organisms.Previous studies on the Jianghan Plain showed that the content of heavy metal elements in the surface soil of the area was almost higher than the national background value,and the single-index pollution of As,Ni and Cd elements was mild and had potential ecological risks.In this paper,the regional soil survey and analysis work was carried out in the key areas of Xiantao,Hubei Province,and the soil element content,spatial distribution and pollution characteristics of the area were identified.The bioavailability analysis of soil Cd was carried out,and the cadmium of rice was established.The content prediction model was based on the multi-target survey area of Hubei Province,which carried out soil heavy metal risk assessment and land use zoning.The physicochemical properties of the surface soil in the study area were statistically analyzed and compared with the soil background values of the whole country and Hubei Province.It was found that the Cd in the soil heavy metals was particularly prominent,which was three times the national background value;the Cd pollution degree was evaluated,and 93.58%of the soil in study area was clean;factor analysis showed that the soil cadmium source may have soil parent material,biological and organic matter accumulation,human activity interference and salt mine distribution.According to the rice-root soil samples,the bioavailability of cadmium w as evaluated.The enrichment factor K?the Cd content of rice compared with t he Cd content of soil?indicates the bioavailability of cadmium.The main facto rs affecting K are soil pH.S,Mn,the correlation between them is negatively correlated.The predicted model for cadmium in rice is:Log(K_Cd)=4.555-0.269p H-0.837log?S?-0.521log?Mn?.Using the prediction model and the surface soil data of multi-target geochemical survey in Hubei Province to predict the content of cadmium in rice,the environmental risk assessment of soil heavy metal and rice cadmium content in the multi-target geochemical survey area of Hubei Province was carried out.The pollution of heavy metals in the soil is environmentally friendly.The clean area accounts for 90.74%.The excessive level of cadmium in rice is higher,and the proportion of samples below the national food safety standard?0.20?g/g?is 55.59%.The proportion above cadmium meter limit value?1.00?g/g?is 0.32%.Land use zoning was carried out on the study area using various schemes,and the results of different land use zoning were compared.It was found that based on the detailed plan for agricultural land pollution,67.64%of the agricultural land was given priority protection,and 0.02%of the land was strictly controlled.However,the priority protection of the land use zoning scheme based on soil and rice seed safety was 55.59%,7.62.The area of%is safely utilized.In contrast,the area of priority protection is reduced,and the area for safe utilization and structural adjustment needs to be increased.The structural adjustment area corresponds to the over-standard area of predicted content of cadmium in rice,which shows the need for crop safety in land use zoning as an important reference.