铜、铬、铅和砷对自然水体生物膜吸附五氯酚的影响

为了解重金属和有机氯杀虫剂两类持久性有毒物质在自然水体生物膜上共吸附过程中的交互作用,对比研究了Cu、Pb、Cr和As四种重金属在浓度和环境p H变化条件下对生物膜吸附五氯酚(PCP)的影响。结果表明,四种重金属均对生物膜吸附PCP产生了抑制作用,且抑制作用随重金属浓度与PCP浓度比值的增加而增强。其中,Cu对生物膜吸附PCP的抑制作用最为显著。在共存Cu与PCP浓度比值为4.0时,最多可使PCP吸附量减少达53.5%。结合Boehm滴定结果,可认为重金属对PCP吸附的抑制作用主要是因为重金属与PCP在生物膜上发生了竞争吸附。与中性条件相比,酸性条件下吸附体系中的重金属与生物膜的结合能力提高,其对生物膜吸附PCP的抑制作用增强,而碱性条件下的抑制作用则有所减弱。

Effects of Cu, Cr, Pb and As on Sorption of PCP on Biofilms in Natural Waters

In order to understand the interaction between heavy metals and organochlorine pesticides, which are persistent toxic substances, in the process of their co-sorption on natural biofilms, effects of Cu, Cr, Pb and As in different concentrations and pH values on the sorption of pentachlorophenol (PCP) onto biofilms were investigated. Results indicated that all the four heavy metals decreased the sorption of PCP on biofilms and the degree of decrease was enhanced with the increasing concentration ratio of heavy metals to PCP. Cu was the most significant to decrease the sorption among these metals, which reduced the PCP sorption amount by 53.5% when the concentration ratio of Cu to PCP was 4.0. Results of Boehm titration inferred that the sorption inhibition could be caused by the competition of heavy metals with PCP on the sorption sites in biofilms. The sorption inhibition was enhanced in acid conditions, whereas it was weakened in base conditions. This is because combining abilities of heavy metals with biofilms are different under the conditions of different pH values.