不同来源生物炭对砷在土壤中吸附与解吸的影响

采用OECD Guideline 106批平衡方法研究了由凋落松针、玉米秸秆、牛粪制备的3种生物炭对As(Ⅴ)在棕壤中的吸附和解吸特性的影响.结果表明：3种生物炭的添加量为0.5%时，对As(Ⅴ)在土壤中的吸附量大小顺序为牛粪炭处理＞松针炭处理＞玉米秸秆炭处理，这与生物炭的基本性质密切相关；等温吸附曲线能用Langmuir方程进行很好的拟合(R² =0.997)；与对照相比，生物炭处理对砷的吸附容量(lgK_f 为1.99～2.10)和吸附强度(1/N 为0413～0.449)降低，生物炭对As(Ⅴ)的主要吸附机制为物理吸附；生物炭处理对As(Ⅴ)解吸率大小顺序为：玉米秸秆炭处理＞松针炭处理＞牛粪炭处理，解吸率在14.5%～18.7%.添加3种来源生物炭降低了棕壤对As(Ⅴ)的吸附，这可能会导致砷的有效性增强，更易被生物吸收，进而增强土壤中砷的毒性.

Effects of biochars produced from different sources on arsenic adsorption and desorption in soil.

By using OECD Guideline 106 batch equilibrium method, this paper studied the characteristics of As (Ⅴ) adsorption and desorption in brown soil as affected by the biochars produced from dairy manure, pine needle, and corn straw. When the addition amount of the biochars was 0.5%, the maximum adsorption amount of As (Ⅴ) was decreased in the order of dairy manure biochar > pine needle biochar > corn straw biochar, which was related to the basic characteristics of the biochars. The adsorption isotherm of As (Ⅴ) could be well fitted by Langmuir model (R2= 0.997). In comparing with CK, both the adsorption capacity (lgKf=1.99-2.10) and the adsorption intensity (1/N=0.413-0.449) of As (Ⅴ) were low, and the main adsorption mechanism was physical adsorption. The desorption rate of As (Ⅴ) (14.5%-18.7%) was decreased in the order of dairy manure biochar > pine needle biochar > corn straw biochar. The addition of the biochars decreased the adsorption of As (Ⅴ) by brown soil, which could induce the increase of the bioavailability of As, and strengthen the toxicity of As in soil.