Centre for Landscape and Climate Research, School of Geography, Geology and the Environment, University of Leicester, Leicester, UK.
Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan, USA.
Integr Environ Assess Manag. 2022 May;18(3):599-621. doi: 10.1002/ieam.4507. Epub 2021 Sep 16.
Multimedia fate and transport models (MFTMs) describe how chemicals behave in the environment based on their inherent properties and the characteristics of receiving systems. We critically review the use of MFTMs for understanding the behavior of volatile methylsiloxanes (VMS). MFTMs have been used to predict the fate of VMS in wastewater treatment, rivers, lakes, marine systems, and the atmosphere, and to assess bioaccumulation and trophic transfers. More widely, they have been used to assess the overall persistence, long-range transport potential (LRTP), and the propensity for atmosphere-surface exchange. The application of MFTMs for VMS requires particularly careful selection of model inputs because the properties of VMS differ from those of most organic compounds. For example, although n-octanol/water partition coefficient (K ) values are high, air:water partition coefficient (K ) values are also high and n-octanol/air partition coefficient (K ) values are relatively low. In addition, organic carbon/water partition coefficient (K ) values are substantially lower than expectations based on K . This means that most empirical relationships between K and K are not appropriate. Good agreement between modeled and measured concentrations in air, sediment, and biota indicates that our understanding of environmental fate is reasonable. VMS compounds are "fliers" that principally partition to the atmosphere, implying high LRTP, although they have low redeposition potential. They are degraded in air (half-lives 3-10 days) and, thus, have low overall persistence. In water, exposure can be limited by hydrolysis, volatilization, and partitioning to sediments (where degradation half-lives are likely to be high). In food webs, they are influenced by metabolism in biota, which tends to drive trophic dilution (i.e., trophic magnification factors are often but not always <1). Key remaining uncertainties include the following: (i) the strength and direction of the temperature dependence for K ; (ii) the fate of atmospheric reaction products; and (iii) the magnitude of emissions to wastewater. Integr Environ Assess Manag 2022;18:599-621. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
多媒体命运和传输模型 (MFTMs) 根据化学物质的固有特性和接收系统的特征来描述它们在环境中的行为。我们批判性地审查了 MFTMs 用于理解挥发性甲基硅氧烷 (VMS) 行为的用途。MFTMs 已被用于预测 VMS 在废水处理、河流、湖泊、海洋系统和大气中的命运，以及评估生物积累和营养转移。更广泛地说，它们还被用于评估整体持久性、长距离迁移潜力 (LRTP) 和大气-表面交换的倾向。MFTMs 在 VMS 中的应用需要特别小心地选择模型输入，因为 VMS 的性质与大多数有机化合物不同。例如，尽管正辛醇/水分配系数 (Kow) 值较高，但空气/水分配系数 (Kaw) 值也较高，正辛醇/空气分配系数 (Koa) 值相对较低。此外，有机碳/水分配系数 (Koc) 值远低于基于 Kow 的预期值。这意味着大多数 Kow 与 Kaw 之间的经验关系都不合适。空气、沉积物和生物群中模型预测浓度与实测浓度之间的良好一致性表明，我们对环境命运的理解是合理的。VMS 化合物是“飞人”，主要分配到大气中，这意味着它们具有很高的 LRTP，尽管它们的再沉积潜力较低。它们在空气中降解（半衰期 3-10 天），因此整体持久性较低。在水中，暴露可能受到水解、挥发和分配到沉积物（降解半衰期可能很高）的限制。在食物网中，它们受生物群代谢的影响，这往往会导致营养稀释（即营养放大因子通常但不总是<1）。关键的剩余不确定性包括以下几点：(i) Kow 的温度依赖性的强度和方向；(ii) 大气反应产物的命运；以及 (iii) 废水排放的程度。2022 年综合环境评估与管理 599-621。© 2021 作者。综合环境评估与管理由 Wiley Periodicals LLC 代表环境毒理与化学学会 (SETAC) 出版。
