土壤-水体系中固/液比对溶解性石油烃吸附的影响

Effects of Solid-to-Solution Ratio on Sorption of Dissolved Petroleum Hydrocarbons to Soils

采用批实验的方法,研究了2种土壤在不同的固/液比(solid-to-solution ratio,SSR)条件下对溶解性石油烃(DPH)的吸附-解吸特性.结果表明,DPH在土壤中的吸附-解吸等温线符合线性方程;解吸表现出明显的滞后现象,滞后因子随SSR的升高而增加,随土壤有机碳含量(OC)的升高而减小,对于OC=1.54%的稻田土,当SSR从10.00 g.L-1变化至75.00 g.L-1,DPH的解吸滞后因子从1.43升高到2.21;对于OC=15.91%的黑土,当SSR从2.50 g.L-1变化至5.00 g.L-1,DPH的解吸滞后因子从1.18升高到1.37.说明吸附的不可逆性随SSR的升高而增强,随土壤有机碳含量的升高而减弱.另外,研究发现由吸附等温线计算得到的KOC随SSR的升高(不可逆性的增强)而减小,在此基础上建立了固定体系中KOC与SSR的关系模型,用于预测实际环境中DPH在土-水界面的迁移.

The influence of solid-to-solution ratio （SSR） on the sorption and desorption of dissolved petroleum hydrocarbons （DPH） to two surface soils （agricultural and black） was evaluated by batch reactor experiments. Previous characterization suggested that the organic carbon content （OC） of black soil was higher. The sorption and desorption isotherms at different SSRs fit well to a linear equation. Desorption hysteresis due to sorption irreversibility was observed and hysteresis index （HI） used to quantify the desorption hysteresis increased from 1.43 to 2.21 with increasing SSR from 10.00 g·L^-1 to 75.00 g·L^-1 for agricultural soil （OC = 1.54% ） and increased from 1.18 to 1.37 with increasing SSR from 2.50 g·L^-1 to 5.00 g·L^-1 for black soil （ OC = 15.91% ）, indicating that an increase of SSR and decrease of OC of soils caused a simultaneous increase in sorption irreversibility of DPH. The organic-carbon-normalized sorption coefficients （Koc） derived from sorption isotherms, were dependent on SSR. A SSR-effect isotherm equation for a given system, which could be applied in the extrapolation of batch-measured sorption parameters to field conditions, was established.