Isotopic provenancing of Pb in Mitrovica, northern Kosovo: source identification of chronic Pb enrichment in soils, house dust and scalp hair

Mitrovica, northern Kosovo, is the site of some of the highest Pb concentrations reported in human populations; exemplified by Pb concentrations in scalp hair of up to 130 μg g-1 and widely-publicized of Pb-related ill-health and mortality amongst internally displaced populations. High human Pb burdens are accompanied by elevated concentrations of potentially harmful elements (PHEs) in soils and house dust within the city, which has a long history of mining and metallurgy. In this study enrichment-levels for PHEs in soils are quantified and compared to environmental quality guidelines and a statistically-derived estimation of background concentration. In addition, Pb isotopes (207Pb/206Pb, 208Pb/206Pb) are used to characterise the isotopic signatures of potential point sources of Pb and a mixing model employed to quantify the contribution of sources to Pb present in soils, house dust, and the scalp hair of children and young people. Pb isotopic evidence suggests that Pb in surface soils and house-dust is predominantly sourced from historical deposition of Pb-containing aerosols from metal smelting, with lower contributions from wind-blown dispersal of metalliferous waste. Pb present in scalp hair is interpreted as the result of non-occupational exposure and the ingestion and/or inhalation of Pb-enriched surface soil and house dust. This study represents one of the very few instances where this type of geochemical tracing technique has been successfully applied to definitively identify the source of Pb present within biological samples. The results of this study are of particular relevance to environmental management and highlight the human health risk posed by the legacy of now inactive mining and metallurgy in addition to the challenge posed in mitigating the risk posed by diffuse soil pollution. © 2015 Elsevier Ltd

River sediment geochemistry and provenance following the Mount Polley mine tailings spill, Canada:The role of hydraulic sorting and sediment dilution processes in contaminant dispersal and remediation

The failure of the Mount Polley tailings storage facility (TSF) in August 2014 was one of the largest magnitude failures on record, and released approximately 25 Mm3 of material, including c. 7.3 Mm3 of tailings into Hazeltine Creek, part of the Quesnel River watershed. This study evaluates the impact of the spill on the geochemistry of river channel and floodplain sediments and utilizes Pb isotope ratios and a multi-variate mixing model to establish sediment provenance. In comparison to sediment quality guidelines and background concentrations, Cu and V were found to be most elevated. Copper in river channel sediments ranged from 88-800 mg kg-1, with concentrations in sand-rich and clay/silt-rich sediments being statistically significantly different. Concentrations in river channel were believed to be influenced by hydraulic sorting during the rising and falling limbs of the flood wave caused by the tailings spill. Results highlight the importance of erosive processes, instigated by the failure, in incorporating soils and sediments into the sediment load transported and deposited within Hazeltine Creek. In this instance, these processes diluted tailings with relatively clean material that reduced metal concentrations away from the TSF failure. This does however, highlight environmental risks in similar catchments downstream of TSFs that contain metal-rich sediment within river channels and floodplain that have been contaminated by historical mining

Mapping hotspots of malaria transmission from pre-existing hydrology, geology and geomorphology data in the pre-elimination context of Zanzibar, United Republic of Tanzania

Background: Larval source management strategies can play an important role in malaria elimination programmes, especially for tackling outdoor biting species and for eliminating parasite and vector populations when they are most vulnerable during the dry season. Effective larval source management requires tools for identifying geographic foci of vector proliferation and malaria transmission where these efforts may be concentrated. Previous studies have relied on surface topographic wetness to indicate hydrological potential for vector breeding sites, but this is unsuitable for karst (limestone) landscapes such as Zanzibar where water flow, especially in the dry season, is subterranean and not controlled by surface topography. Methods: We examine the relationship between dry and wet season spatial patterns of diagnostic positivity rates of malaria infection amongst patients reporting to health facilities on Unguja, Zanzibar, with the physical geography of the island, including land cover, elevation, slope angle, hydrology, geology and geomorphology in order to identify transmission hot spots using Boosted Regression Trees (BRT) analysis. Results: The distribution of both wet and dry season malaria infection rates can be predicted using freely available static data, such as elevation and geology. Specifically, high infection rates in the central and southeast regions of the island coincide with outcrops of hard dense limestone which cause locally elevated water tables and the location of dolines (shallow depressions plugged with fine-grained material promoting the persistence of shallow water bodies). Conclusions: This analysis provides a tractable tool for the identification of malaria hotspots which incorporates subterranean hydrology, which can be used to target larval source management strategies