The Effects Of Biochar On Environmental Behavior And Bioavailability Of Acetochlor In Soil

Acetochlor is one of the most widely used herbicides in China.As an endocrine disruptor and a potential carcinogen,acetochlor has great environmental risks and it may pose potential threats to environmental organisms and crops.Therefore,it is very important to acknowledge the environmental behavior and bioavailability of acetochlor and find the appropriate method to control environmental pollution of the herbicide.By applying biochar into the soil,this study explored the influences ofbiochar on environmental behaviors and bioavailability to maize.Here are the main research results:1.The sorption capacity of three different kinds of biochars on acetochlor were investigated.It showed that biochars have strong adsorption capacity to acetochlor.The biochar made from rice husk?BCR?has the strongest sorption capacity among the three biochars.And the K_f value of BCR was309.96 L/kg.It showed that the specific surface area of biochar is the main factor affecting the adsorption capacity of acetochlor.2.Effects of different kinds and quantities of biochar on the degradation of acetochlor in soil were studied.It was found that the degradation rate of the herbicide was delayed by biochars.The half-lives of acetochlor in soil without biochar was 11.95 d,however,the half-lives of acetochlor in soils amended with biochars?BCH,BCW,BCR?were 24.7,19.8,99.0 d,respectively.We found that with the enhancement of biochar adsorption capacity to acetochlor,the ability to inhibit the degradation of acetochlor become stronger.As the quantities of biochar?BCH?in soils increased,the half-lives of acetochlor in soils increased.The half-lives of the soils containing BCH were 16.11 d?0%BCH?,18.73d?0.1%BCH?,21.66 d?0.5%BCH?,24.76 d?1%BCH?,28.88 d?1.5%BCH?respectively.3.By applying biochar to the soil,it showed that biochar has significant influence on the bioavailability of acetochlor to maize seedling.In the shorter aging time of the soil amended with BCH,BCH could increase the biomass of maize seedlings,and it could also decrease the bioconcentration factor?BCF?and the root concentration factor?RCF?.However,as the aging time increased,the concentrations of acetochlor increased and the biomass of acetochlor decreased.As a result,the BCFs and RCFs were increased by aged BCH.4.Four chemical methods were compared to evaluate the bioavailability of acetochlor in soil.It showed that the correlation between concentrations extracted by Tenax(C_tenax)and the concentrations in the maize seedlings(C_maize)is significantly?R²=0.8449,P<0.01?.And Tenax method is not affected by the influences of biochar and the aging time.The results showed that Tenax method could be used in evaluating the bioavailability of acetochlor in soil.