生物质炭及老化过程对土壤吸附吡虫啉的影响

Effect of biochars and aging process on soil adsorption of imidacloprid

通过批处理恒温振荡法,系统考察了土壤类型(熟化红壤、新垦红壤)、生物质炭种类(竹炭、稻草炭)、生物质炭用量(0、0.1%和0.5%,质量分数)及老化过程(恒湿30 d)对土壤吸附吡虫啉的影响.Freundlich曲线描述的研究结果表明,有机质含量高的熟化红壤对吡虫啉的吸附能力强于有机质含量低的新垦红壤.生物质炭的添加能增强土壤对吡虫啉的吸附能力,且吸附能力随生物质炭施用量的增加而显著提高.添加等量生物质炭,新垦红壤吸附吡虫啉能力的增强效果强于熟化红壤;在同种土壤中添加不同种类的等量生物质炭,新垦红壤添加稻草炭后吸附能力更强,熟化红壤添加竹炭后吸附能力更强.恒湿老化后的处理对吡虫啉的吸附能力与新鲜处理相比明显降低,且添加竹炭的处理比稻草炭处理受老化过程影响更大.

A laboratory study was conducted to evaluate the effects of bamboo-derived biochar( BC),rice straw-derived biochars( SC) and aging process on adsorption of imidacloprid in two types of soils with contrasting properties. Biochars were mixed with the high organic carbon content soil( HS) and low organic carbon content soil( LS) at rates of 0.1% and 0.5%( w / w). A 30-day incubation with 0.5% biochar treatments was also conducted to evaluate the effect of aging of biochars on adsorption of imidacloprid. A batch equilibration method was used to determine the adsorption of imidacloprid to soils. The Freundlich isotherms were used to describe the results of adsorption processes. It was found that imidacloprid adsorption to the HS was higher than that to the LS. Biochar addition enhanced the adsorption of imidacloprid to the soils. Higher loading rates of biochar resulted in higher values of Kf,indicating stronger imidacloprid adsorption capacity of the soil. The effect of biochar on the enhancement of imidacloprid adsorption was influenced by soil organic carbon content. The effect of biochar on adsorption capacity in the LS was greater than that in the HS. In the LS,the effect of SC on imidacloprid adsorption was greater than that of BC,while in the HS,the effect of BC was greater than of SC. The Kfvalues of aged biochar treatments were significantly lower than those of the biochar treatments without aging. The reduction of adsorption capacity in the aged BC treatment was greater than that in the SC treatment.