Antimony derived from brake linings in roadside soils, road run-off, and affected streams

锑(Sb)及其化合物被国家和国际环境当局(如世界卫生组织、美国环保局、欧洲共同体理事会)视为高度优先关注的污染物，因为它们具有致癌潜力。然而，这种半金属材料被添加到刹车衬片的摩擦材料中，并由于制动过程中的磨损而释放到环境中。这项建议的目的是(I)提供关于路旁土壤中总Sb的空间分布模式的详细信息，以及(Ii)更好地了解Sb的迁移性和形态(三价Sb与五价Sb)及其在这些土壤中的空间分布模式。除了用强无机酸微波消解测定总Sb外，还将采用顺序提取程序来评估Sb的流动性和生物利用度。该程序包括测定弱酸溶、可还原、可氧化和残留组分。为了测定Sb(III)和Sb(V)，必须从样品基质中可靠地定量提取Sb，而不对其物种进行任何降解或转化，但仍具有代表性的提取效率。我们将应用和调整已经测试的提取方法，以适应更广泛的土壤样本和变化，以开发一种对基质依赖较少的程序。此外，还将研究(Iii)道路径流中Sb的形态和粒度分级，以及(Iv)排放道路径流对排水溪流中Sb的形态和粒度分级的影响。水质参数的变化，如pH、离子强度、氧化还原电位、温度和溶解氧，都会影响水生系统中的金属形态。我们将通过在降雨期间对道路径流进行形态和粒度分级，以及在道路径流出口下游的排水系统进行长期变化来研究这些影响。粒度分级将提供更多关于水生系统中Sb结合形式的信息。已知Sb主要残留在低分子质量(LMM)组分中。这是非常令人担忧的，因为LMM物种被认为比与颗粒相关的物种更容易获得生物利用。然而，这两种分析方法从未在路边径流及其影响的排水系统中进行过。所有这些目标都有一个共同的目的：更好地了解制动衬里衍生的Sb如何存在于路边土壤和相关的排水系统中。环境样品中Sb物种的分布对毒性效应的评价至关重要，因为Sb的毒性取决于其氧化状态。

Antimony (Sb) and its compounds are considered as a pollutant of high priority interest by national and international environmental authorities (e.g., WHO, US E.P.A., Council of the European Communities) as they have carcinogenic potential. Nevertheless, this semimetal is added to friction material in brake linings and released into the environment due to abrasion during the braking process. The objectives of this proposal are (i) to yield detailed information about the spatial distribution patterns of total Sb in thoroughly characterized roadside soils, and (ii) to provide an improved understanding of Sb's mobility and speciation (tri- versus pentavalent Sb) and its spatial distribution patterns in those. Besides the determination of total Sb by microwave digestion using strong mineral acids, a sequential extraction procedure will be applied to assess the mobility and bioavailability of Sb. The procedure includes the determination of the weak acid-soluble, reducible, oxidizable, and residual fractions. To determine Sb(III) and Sb(V), a reliable quantitative extraction of Sb from the sample matrix must be applied without any degradation or transformation of its species, but still with representative extraction efficiency. We will apply and adjust already tested extraction methods to a wider range and variation of soil samples in order to develop a less matrix-dependent procedure. Moreover, the (iii) speciation and size fractionation of Sb in road run-off, and (iv) the effects of discharged road run-off on the speciation and size fractionation of Sb in a drainage stream will be investigated. Variations in water quality parameter such as pH, ionic strength, redox potential, temperature, and dissolved oxygen have an influence on metal speciation in aquatic systems. We will study these effects by conducting speciation and size fractionation in both road run-offs during rain events, and long-term variations in a drainage system downstream of an outlet of road run-off. Size fractionation will provide more information about binding forms of Sb in aquatic systems. It is known that Sb mainly remains in the low molecular mass (LMM) fraction. This is of great concern, as LMM species are believed to be more bioavailable than particle-associated species. Nevertheless, both analytical approaches have never been conducted in roadside run-off and its affected drainage system. All these objectives share a common purpose: to provide a better understanding of how brake-lining-derived Sb is present in roadside soils and related drainage systems. Distribution of Sb species in environmental samples is crucial for the evaluation of toxic effects, since Sb toxicity depends on its oxidation state.