Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Environ Sci Technol. 2011 Apr 1;45(7):2641-7. doi: 10.1021/es103729m. Epub 2011 Feb 25.
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.
研究了微囊藻毒素（MCs）在 15 种湖泊沉积物和 4 种粘土矿物上的吸附行为，作为沉积物/粘土特性、温度和 pH 的函数，通过严格控制的批量吸附实验进行。所有沉积物和粘土的吸附数据均很好地用非线性 Freundlich 模型描述（n(f) 在 0.49 到 1.03 之间变化）。MCs 的吸附过程在不同的湖泊沉积物中表现出不同的吸附机制，主要取决于沉积物中的有机物（OM）。对于 OM 较低（即低于 8%）的沉积物，MCs 的吸附随着 OM 的增加而减少，主要是由于 MCs 和 OM 之间的吸附位点竞争。相比之下，富含 OM（即超过 8%）的沉积物中 MCs 的吸附随着 OM 的增加而增加，主要是由于 MCs 和吸附的 OM 之间的相互作用。MCs 对沉积物的吸附热力学表明，MCs 的吸附是一种自发的物理吸附过程，存在两种不同的机制。一种机制是 OM 较低的沉积物的放热过程，另一种机制是 OM 较高的沉积物的吸热过程。此外，MCs 对沉积物的吸附受 pH 值的影响（吸附随 pH 值的增加而降低）。这些结果为更好地理解水生生态系统中 MCs 的自然非生物衰减机制提供了有价值的信息。
