title: Mechanisms and factors affecting sorption of microcystins onto natural sediments.
abstract: The sorption of microcystins (MCs) to fifteen lake sediments and four clay minerals was studied as a function of sediment/clay properties, temperature, and pH through well-controlled batch sorption experiments. All sorption data for both sediments and clays are well described by a nonlinear Freundlich model (n(f) varies between 0.49 and 1.03). The sorption process for MCs exhibited different adsorptive mechanisms in different lake sediments mainly dependent on the sediment organic matter (OM). For sediments with lower OM (i.e., less than 8%), the sorption of MCs decreases with increasing OM and is dominated by the competition for adsorption sites between MCs and OM. In contrast, MC sorption to organic-rich (i.e., more than 8%) sediments increases with increasing OM and is dominated by the interaction between MCs and adsorbed OM. The sorption thermodynamics of MCs onto sediments showed that MC sorption is a spontaneous physisorption process with two different mechanisms. One mechanism is an exothermic process for sediment with lower OM, and the other is an endothermic process for sediment with higher OM. Furthermore, the sorption of MCs onto sediments is pH dependent (sorption decreased with increasing pH). These results provide valuable informations for a better understanding of the natural abiotic attenuation mechanisms for MCs in aquatic ecosystems.
authors: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors: Xingqiang
authors: X
authors: Wu
authors: Bangding
authors: B
authors: Xiao
authors: Renhui
authors: R
authors: Li
authors: Chunbo
authors: C
authors: Wang
authors: Jiantuan
authors: J
authors: Huang
authors: Zhi
authors: Z
authors: Wang
mesh_terms: D000327:Adsorption; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D052998:Microcystins / Q000737:chemistry*; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D052998:Microcystins; D014874:Water Pollutants, Chemical