Forensic Assessment of Metal Contaminated Rivers in the 21st Century Using Geochemical and Isotopic Tracers

Abstract

Documentation of contaminant source and dispersal pathways in riverine environments is essential to mitigate the potentially harmful effects of contaminants on human and ecosystem health, and is required from a legal perspective (particularly where the polluter pays principle is in effect) in assessing site liability. Where multiple natural and/or anthropogenic sources exist, identification of contaminant provenance has proven problematic, and estimated contributions from a specific source are often the subject of judicial debate. The past, current, and future use of geochemical and isotopic tracers in environmental forensic investigations of contaminant provenance, transport, and fate are analyzed herein for sediment-associated trace metals in riverine environments, particularly trace metals derived from mining and refining operations. The utilized methods have evolved significantly over the past four decades. Of primary significance has been the growing integration of geomorphic and stratigraphic techniques with the use of an increasing number of geochemical tracers including stable isotopes. The isotopes of Pb have been particularly well studied, and have been applied to a wide range of environmental media. Advances in analytical chemistry since the early 1990s have allowed for the precise characterization of other non-traditional stable isotopic systems within geological materials. The potential for using these non-traditional isotopes as tracers in river systems has yet to be adequately explored, but a number of these isotopes (e.g., Cd, Cu, Cr, Hg, Sb, and Zn) show considerable promise. Moreover, some of these isotopes (e.g., those of Cu, Cr, and Hg) may provide important insights into biogeochemical cycling processes within aquatic environments. This review suggests that future environmental forensic investigations will be characterized by an interdisciplinary approach that combines the use of multiple geochemical tracers with detailed stratigraphic, geomorphic, and hydrologic data, thereby yielding results that are likely to withstand the scrutiny of judicial review.

Application of lead isotopic methods to the study of the anthropogenic lead provenance in Spanish overbank floodplain deposits

“…Afterwards, they were disaggregated and sieved to \63 lm grain size. Anthropogenic Pb may preferentially associate with the chemically active silts and clays (Bird 2011), while larger floods appear to deposit relatively coarse-grained sediment on the floodplain characterized by lower trace metal concentrations (Miller 2013). To compensate for the grain size differences, it was decided to carry out the study with this fraction (\63 lm).…”

“…A single profile can form a historical record of the chemical and mineralogical conditions, during the successive floods that have built it (Ottesen et al 1989). However, hydraulic sorting processes (particle size or density) often result in a spatially nonuniform distribution of contaminants across the floodplain (Macklin 1996;Miller 2013).…”

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“…Os trabalhos de Bataille e colaboradores buscam, portanto, mapear as variações isotópicas de Sr no território, possibilitando, assim, relacionar a composição isotópica desse elemento com a origem geográfica de um dado material. A partir dessa estratégia, pode-se inferir o local de origem de minerais, fauna e flora em um determinado território, à semelhança dos estudos que abordam a variação isotópica de fauna silvestre em rios da Amazônia (Weiss, Rehkämper et al 2008, Miller 2013, Dauphas, John et al 2017, Kendall, Dahl et al 2017, Teng, Dauphas et al 2017.…”

“…De certa forma, a determinação das razões isotópicas desses elementos foi uma verdadeira revolução no entendimento dos processos naturais, pois se assumia que seus isótopos não eram afetados por processos de fracionamento, à semelhança do que ocorre com os elementos leves. A possibilidade de se determinar essas variações isotópicas abriu novas perspectivas para o desenvolvimento de traçadores isotópicos em uma vasta gama de materiais (Weiss, Rehkämper et al 2008, Miller 2013, Dauphas, John et al 2017, Kendall, Dahl et al 2017, Teng, Dauphas et al 2017.…”

Structure and magnetic properties of melt-spun Mn-Ga-Cu-Al ribbons

“…With good magnetic properties, rare earth magnets (Nd-Fe-B and Sm-Co) are widely used in practice [1][2][3]. However, the issue of the exploitation and utilization of rare earth elements is a global concern because of the scarcity, the monopoly of the nations, the environmental pollution... [4][5][6]. Therefore, the technological research to avoid using rare earth in the hard magnetic materials is essential.…”