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首页> 外文学位 >Application of particle size fractionation methods to the study of trace metal speciation in urban runoff: Implications for total maximum daily load analyses.
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Application of particle size fractionation methods to the study of trace metal speciation in urban runoff: Implications for total maximum daily load analyses.

机译：粒度分级法在城市径流中痕量金属形态研究中的应用：对总最大日负荷分析的启示。

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Trace and heavy metals are among the most ubiquitous pollutants in surface waters and sediments. Nonpoint source runoff is recognized as a leading source of impairment to aquatic life support and other beneficial uses. Runoff transports a complex mixture of pollutants and suspended particles into surface waters, where the fate depends significantly on physical speciation. The goal of this dissertation was to provide a framework for characterizing the physical and chemical speciation of trace metals in urban runoff.; This goal was accomplished first by studying the particle size separation characteristics of 0.45 mum membrane filters and tangential flow filtration systems (0.1 mum and 3000 MW cutoffs) used to separate colloidal particles from dissolved constituents. This research shows that 0.45 mum membrane filtration has distinct limitations in size fractionation studies, and that a significant amount of colloidal metals are present in the 0.1 to 1.0 mum size range in freshwaters.; Suspended sediments were fractionated at 80 mum and 20 mum by membrane filtration. Application of size fractionation techniques to urban stormwater shows that metals in urban runoff (for a winter storm on the Naugatuck River below Torrington, CT and for a fall storm on Steele Brook, Watertown, CT) were present mainly in the 20 to 80 mum size range. During storm events, colloidal organic carbon and associated metal concentrations responded differently depending on the source of organic carbon. Cu speciation, measured at an urban and upstream site in Steele Brook by electrochemical methods, showed that concentrations of free copper were typically 10 times higher at the urban location.; Assessment of the state of Connecticut's total maximum daily load (TMDL) program showed that urban runoff and other nonpoint sources are the greatest source of impairment to surface waters in the state. Connecticut's TMDL program does not adequately prioritize nonpoint source control, and most TMDL actions involve localized, single source impairments. A case study of the Steele Brook TMDL analysis shows that impairment exists even after the removal of point source inputs, and that urban runoff to Steele Brook may provide the remaining source of impairment.
机译：痕量和重金属是地表水和沉积物中最普遍存在的污染物之一。非点源径流被认为是对水生生物维持和其他有益用途造成损害的主要来源。径流将污染物和悬浮颗粒的复杂混合物输送到地表水中，在那里的命运很大程度上取决于物理形态。本文的目的是为表征城市径流中痕量金属的物理形态和化学形态提供一个框架。通过研究用于分离胶体颗粒和溶解成分的0.45微米膜滤器和切向流过滤系统（0.1微米和3000兆瓦截止值）的粒径分离特性，可以首先实现该目标。这项研究表明，0.45微米的膜过滤在尺寸分级研究中有明显的局限性，并且在淡水中0.1到1.0微米尺寸范围内存在大量的胶态金属。通过膜过滤将悬浮的沉淀物在80μm和20μm下分级。粒度分级技术在城市雨水中的应用表明，城市径流中的金属主要存在于20至80毫米的范围内（对于康涅狄格州托灵顿以下的Naugatuck河上的冬季暴风雨和康涅狄格州沃特敦的斯蒂尔布鲁克的秋季暴雨）范围。在暴风雨期间，胶体有机碳和相关金属浓度的响应取决于有机碳的来源而有所不同。用电化学方法在斯蒂尔布鲁克市区和上游站点测量的铜形态表明，市区的游离铜浓度通常高10倍。对康涅狄格州总最大日负荷（TMDL）计划的评估表明，城市径流和其他非点源是该州地表水损害的最大来源。康涅狄格州的TMDL计划没有充分优先考虑非点源控制，大多数TMDL行动都涉及局部的单源损害。斯蒂尔·布鲁克TMDL分析的一个案例研究表明，即使在删除点源输入后也存在损害，并且斯蒂尔·布鲁克的城市径流可能提供了剩余的损害源。

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