溶解性有机质对菲在沉积物上吸附与解吸性能的影响

采集了北京通州凉水河(标记为L)以及广东东江流域(标记为D)的沉积物,并进行菲(Phe)的连续吸附-解吸实验,研究了不同含量及组成的溶解性有机质(DOMs)对其吸附与解吸性能的影响.结果表明,DOMs能明显抑制菲在沉积物上的吸附,在实验浓度范围内(0~110mg/L),菲在沉积物上的吸附量与DOC浓度呈显著的负线性相关,并且DOC浓度越高,对吸附作用的抑制越显著.在溶解性有机质存在条件下,菲在2种沉积物上的吸附均呈线性吸附特征,kd值随加入沉积物浸出液DOC浓度的减小呈增大的趋势.菲在2种沉积物上的解吸过程均呈现一定的迟滞性,其解吸迟滞性可用热力学指数TII来描述.随着菲初始浓度的增加,TII值先减小后增加,其变化可以用吸附在高低位点上的菲分子比例以及菲分子是否能够被禁锢在吸附剂微孔内部来加以解释;溶解性有机质的存在,能促进菲从沉积物上的解吸,从而使菲的解吸滞后性减弱, 增强其在水环境介质中的迁移与传输能力.

Effects of dissolved organic matters (DOMs) on the sorption and desorption behaviors of phenanthrene by sediments.

The sorption and desorption behaviors of phenanthrene were investigated on two representative sediments collected from Dongjiang(D) and Liangshuihe(L) rivers,respectively,using a batch method.The effects of dissolved organic matters(DOMs) in the sediment extracts on the sorption and desorption performance were studied.The inhibitory sorption of phenanthrene was significant when using DOMs as the aqueous medium of batch experiments,in which an inverse linearity between the adsorption capacity and DOMs content was evident in the DOC concentration range used(0~110mg/L).The higher the DOC concentration was used,the stronger the inhibitory sorption of phenanthrene was identified.With the DOMs added as the medium of batch experiments a linear sorption behavior of phenanthrene on the sediments was obvious,the Kd values of which increase as the DOC concentration was diminished,while desorption hysteresis of phenanthrene could be characterized by the hysteresis indices(TII).As the initial concentration of phenanthrene increases,the TII index decreased first and then went up,which could be explained with the makeup ratios of phenanthrene molecules on the high and low adsorption sites and the extent to which they were confined inside the micropores of adsorbent.The occurrence of DOMs in the adsorption system could facilitate desorption of phenanthrene from the sediments and thus attenuate their desorption hysteresis,promoting the transport and migration ability of contaminants in the aquatic environment medium.