模拟根系分泌物对土壤吸附菲的影响

Effect of artificial root exudates on the sorption of phenanthrene in soils

采用批量平衡试验方法,研究了模拟根系分泌物(ARE)对黄棕壤、棕红壤和红壤吸附菲的影响.结果表明,3种土壤对菲的等温吸附曲线均为线性,加入ARE后,土壤吸附菲的分配系数(Kd)和有机碳标化的分配系数(Koc)显著降低,且降低量随着ARE浓度的增加而增大,表明ARE抑制了土壤对菲的吸附.土壤有机质含量越低,ARE对土壤吸附菲的抑制作用越明显.分析土样吸附菲的平衡溶液中水溶性有机质(DOM)浓度,发现加入ARE后土壤有机质含量略有降低(<1.64%),而DOM浓度增大,DOM与菲的结合作用对土壤吸附菲的抑制作用增强,这可能是ARE抑制土壤吸附菲的主要原因.

The sorption of phenanthrene by three soils with addition of artificial root exudate（ARE） was investigated using a batch experimental method.Phenanthrene sorption isotherms by soils could be significantly described by a liner sorption model irrespective of the addition of ARE.The distribution coefficients（Kd） and the organic carbon-normalized distribution coefficients（Koc） for phenanthrene sorption were significantly lower when ARE present in soils,and Kd and Koc values tended to decrease with increasing the concentrations of ARE in soils.The concentrations of dissolved organic matter（DOM） in equilibrium solution for phenanthrene sorption were detected,and DOM concentrations were higher with the addition of ARE.While the soil organic carbon content was observed to be a little lower with the ARE addition.The combination of DOM and phenanthrene in solution was proposed to dominate the decrease of phenanthrene sorption in soils with the addition of ARE.Results of this work indicated that root exudate clearly inhibited the sorption of PAHs,and thus could enhance their availability in soil environment.