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Modeling chemical accumulation in sediment of small waterbodies accounting for sediment transport and water-sediment exchange processes over long periods

机译：对小水体沉积物中的化学积累进行建模，考虑到长期的沉积物迁移和水沙交换过程

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In a recent scientific opinion of the European Food Safety Authority it is argued that the accumulation of plant protection products in sediments over long time periods may be an environmentally significant process. Therefore, the European Food Safety Authority proposed a calculation to account for plant protection product accumulation. This calculation, however, considers plant protection product degradation within sediment as the only dissipation route, and does not account for sediment dynamics or back-diffusion into the water column. The hydraulic model Hydrologic Engineering Center-River Analysis System (HEC-RAS; US Army Corps of Engineers) was parameterized to assess sediment transport and deposition dynamics within the FOrum for Co-ordination of pesticide fate models and their USe (FOCUS) scenarios in simulations spanning 20 yr. The results show that only 10 to 50% of incoming sediment would be deposited. The remaining portion of sediment particles is transported across the downstream boundary. For a generic plant protection product substance this resulted in deposition of only 20 to 50% of incoming plant protection product substance. In a separate analysis, the FOCUS TOXSWA model was utilized to examine the relative importance of degradation versus back-diffusion as loss processes from the sediment compartment for a diverse range of generic plant protection products. In simulations spanning 20 yr, it was shown that back-diffusion was generally the dominant dissipation process. The results of the present study show that sediment dynamics and back-diffusion should be considered when calculating long-term plant protection product accumulation in sediment. Neglecting these may lead to a systematic overestimation of accumulation. Environ Toxicol Chem 2017;36:3223-3231. (c) 2017 SETAC
机译：欧洲食品安全局的最新科学观点认为，植物保护产品长时间沉积在沉积物中可能对环境具有重大影响。因此，欧洲食品安全局提出了一种计算方法，以考虑植物保护产品的积累。但是，该计算将沉积物中的植物保护产品降解视为唯一的消散途径，并未考虑沉积物动力学或向水柱的反向扩散。对水力模型水文工程中心-河流分析系统（HEC-RAS；美国陆军工程兵）进行了参数设置，以评估FOrum中的泥沙运移和沉积动力学，以协调农药归类模型及其模拟中的USe（FOCUS）方案。跨越20年。结果表明，只有10％到50％的进入沉积物会被沉积。沉积物颗粒的其余部分跨下游边界传输。对于一般的植物保护产品物质，这只会沉积进入植物保护产品物质的20％到50％。在单独的分析中，FOCUS TOXSWA模型用于检验降解和反向扩散（相对于背向扩散）相对重要性的相对重要性，因为对于各种通用的植物保护产品来说，沉积物从沉淀室流失的过程。在20年的模拟中，研究表明，反向扩散通常是主要的耗散过程。本研究结果表明，在计算沉积物中长期植保产品积累时应考虑沉积物动力学和反向扩散。忽略这些可能导致系统地高估积累。 Environ Toxicol Chem 2017; 36：3223-3231。 （c）2017年SETAC

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