Study On The Aging Process And Ecological Threshold Of Antimony In Soil

In this study,the typical farmland soil of 21 species in China were chosen to explore the effect the long-term aging process on the exogenous antimony（Sb）bioavailability.The equilibrium concentration（Qe）and the aging equilibrium time were tested out.Meanwhile,the toxicity of Sb to wheat in different soil was explored;in this part,the accumulation of Sb in the grain was regarded as the evaluation criterion to the Sb toxicity.The species sensitivity distribution（SSD）was used to forecast the safety threshold of Sb in soil.Furthermore,twenty-three kinds of vegetables were selected to conduct the inhibition of root growth experiment in Shandong moisture soil and Jiangxi red loam to explore the safety threshold of vegetables.The aging process significantly reduces the bioavailability of Sb.The Qe and time of different kinds of soils were not equal;at 200 mg/kg Sb contaminated soil,the Qe of Sb was about 3.78-13.32 mg/kg in mud,the compelling state ratio of Sb in equilibrium was about 1.89-6.66%,the equilibrium time was about 8-215 days;while the Sb concentration was at 1600 mg/kg,the Qe of Sb was approximately 22.34-82.59 mg/kg in soil,the compelling state ratio of Sb in equilibrium was about 1.39-5.16%,the equilibrium time was about 12-78 days.The correlation analysis between soil available state content and soil properties shows that there is little correlation between soil available state content and soil physical and chemical properties.Sb accumulation in wheat grains was significantly different among different soils.A pot experiment was conducted to study the expansion of Sb in wheat grains in foreign Sb contaminated soil.The results showed that the sensitivity of wheat to Sb contamination was different in different soils.Taking 0.246 mg/kg as the limit value of antimony in vegetables,the safety threshold for grain based on the total Sb in soil was 142.20mg/kg.Through the correlation analysis of soil available Sb content and soil properties,it is found that there is a significant correlation between soil available state content and soil organic matter content.The inhibition of root elongation by Sb addition varied between two different soils for all vegetables.The range of EC₁₀ and EC₂₀ in Shandong alluvial soil were ranged from 1.38-3754.34 mg/kg and 1.96-7651.24mg/kg,respectively.However,the range of EC₁₀ and EC₂₀ in Jiangxi red loam soil were ranged from1.38³754.34 mg/kg and 1.13³758.48 mg/kg.The EC₁₀ and EC₂₀ on the inhibition of different vegetables root elongation were 11.86 mg/kg and 21.87 mg/kg,respectively,in Shandong alluvial soil.And the EC₁₀ and EC₂₀ on the inhibition of different vegetable root elongation were 1.36 mg/kg and 3.11 mg/kg,respectively,in Jiangxi red loam.The stepwise regression indicated soil CEC was an essential factor affecting the EC₁₀ of Shandong soil.The results of this paper are expected to provide a basis for the establishment of soil Sb standard and enrich the toxicology database.