Impacts of metal mining on river systems: a global assessment.

An estimated 23 million people live on floodplains affected by potentially dangerous concentrations of toxic waste derived from past and present metal mining activity. We analyzed the global dimensions of this hazard, particularly in regard to lead, zinc, copper, and arsenic, using a georeferenced global database detailing all known metal mining sites and intact and failed tailings storage facilities. We then used process-based and empirically tested modeling to produce a global assessment of metal mining contamination in river systems and the numbers of human populations and livestock exposed. Worldwide, metal mines affect 479,200 kilometers of river channels and 164,000 square kilometers of floodplains. The number of people exposed to contamination sourced from long-term discharge of mining waste into rivers is almost 50 times greater than the number directly affected by tailings dam failures.

Flood-related contamination in catchments affected by historical metal mining: an unexpected and emerging hazard of climate change.

Floods in catchments affected by historical metal mining result in the remobilisation of large quantities of contaminated sediment from floodplain soils and old mine workings. This poses a significant threat to agricultural production and is preventing many European river catchments achieving a 'good chemical and ecological status', as demanded by the Water Framework Directive. Analysis of overbank sediment following widespread flooding in west Wales in June 2012 showed that flood sediments were contaminated above guideline pollution thresholds, in some samples by a factor of 82. Most significantly, silage produced from flood affected fields was found to contain up to 1900 mg kg(-1) of sediment associated Pb, which caused cattle poisoning and mortality. As a consequence of climate related increases in flooding this problem is likely to continue and intensify. Management of contaminated catchments requires a geomorphological approach to understand the spatial and temporal cycling of metals through the fluvial system.

Potentially harmful elements (PHEs) in scalp hair, soil and metallurgical wastes in Mitrovica, Kosovo: the role of oral bioaccessibility and mineralogy in human PHE exposure.

Internationally publicized impacts upon human health associated with potentially harmful element (PHE) exposure have been reported amongst internally displaced populations (IDPs) in Mitrovica, Kosovo, following the Kosovan War. Particular concern has surrounded the exposure to Pb indicated by the presence of highly elevated concentrations of Pb in blood and hair samples. This study utilizes a physiologically-based in-vitro extraction method to assess the bioaccessibility of PHEs in surface soils and metallurgical waste in Mitrovica and assesses the potential daily intake of soil-bound PHEs. Maximum As (210mgkg(-1)), Cd (38mgkg(-1)), Cu (410mgkg(-1)), Pb (18790mgkg(-1)) and Zn (8500mgkg(-1)) concentrations in surface soils (0-10cm) are elevated above guideline values. Samples with high PHE concentrations (e.g. As >1000mgkg(-1); Pb >1500mgkg(-1)) exhibit a wide range of bioaccessibilities (5.40 - 92.20% in the gastric (G) phase and 10.00 - 55.80% in the gastric-intestinal (G-I) phase). Samples associated with lower bioaccessibilities typically contain a number of XRD-identifiable primary and secondary mineral phases, particularly As- and Pb-bearing arsenian pyrite, beudantite, galena and cerrusite. Quantification of the potential human exposure risk associated with the ingestion of soil-associated PHEs indicates that on average, 0.01µg Cd kg(-1) BW d(-1), 0.16µg Cu kg(-1) BW d(--1), 0.12µg As kg(-1) BW d(-1), 7.81µg Pb kg(-1) BW d(-1), and 2.68µg Zn kg(-1) BW d(-1) could be bioaccessible following ingestion of PHE-rich soils in the Mitrovica region, with Pb, and to a lesser extent As, indicating the likely possibility of local populations exceeding the recommended tolerable daily intake. Lead present within surface soils of the area could indeed have contributed to the human Pb burden due to the high bioaccessibility of Pb present within these soils (13.40 - 92.20% in the gastric phase). Data for Pb levels in scalp hair (≤120µgg(-1)) and blood (≥650µgdL(-1); WHO, 2004) for children that have lived within IDP camps in Mitrovica indicate significant Pb uptake has indeed taken place. The highly bioaccessible nature of soil-associated PHEs in this study highlights the need for appropriate environmental management approaches that limit the exposure of local populations to these contaminated soils.

Fluvial-controlled metal and As mobilisation, dispersal and storage in the Río Guadiamar, SW Spain and its implications for long-term contaminant fluxes to the Doñana wetlands.

Flood-related contaminant (As, Cd, Cu, Pb, Zn) remobilisation, dispersal and storage in the Río Guadiamar was investigated following the 1998 Aznalcóllar tailings dam failure, along with records of floodplain contaminant loading in the decades preceding the tailings release. A series of post-spill floods resulted in the transfer of vast quantities of sediment-borne heavy metals and As towards the lower reaches of the Guadiamar and the borders of the Doñana National Park, but over-bank flood deposits collected between May 1999 and March 2002 show a systematic fall in contaminant concentrations following successive flood events. Geochemical improvements can largely be attributed to sediment mixing of contaminated and 'clean' material derived from calcareous catchment soils. Longer-term contaminant patterns in floodplain sediment cores show higher heavy metal and As loading rates operating before the opening of the Aznalcóllar pit in 1979 and in some instances pre-dating 1954. The remobilization and dispersal of historically contaminated alluvium in the upper Guadiamar means that the post-clean-up contaminant signature in flood-transported sediments largely reflects chronic, long-term metal mining in the Guadiamar catchment, rather than the acute effects of the Aznalcóllar spill. Generally results present a cautiously optimistic prognosis for the sensitive wetlands of Doñana, but high dissolved (aqueous) heavy metal (especially Cu and Zn) concentrations in the upper Guadiamar emphasise the need for addressing contaminant 'hotspots' in the region and for maintaining flow requirements for aquatic ecosystems. This study illustrates the importance of establishing antecedent geomorphological-geochemical conditions in a spill-impacted river system, both for assessing the impacts of a single catastrophic pollution event and for developing appropriate strategies for remediation.

Patients with alcohol problems in the emergency department, part 2: intervention and referral. SAEM Substance Abuse Task Force. Society for Academic Emergency Medicine.

Early intervention and appropriate referral of patients with alcohol problems have the potential to reduce alcohol-related morbidity and mortality. Part 1 of this series introduced screening tools that can be applied in the ED to allow early detection of at-risk drinkers. This article was developed by members of the SAEM Substance Abuse Task Force and describes assessment and intervention techniques once the at-risk or dependent drinkers has been identified. Appropriate aftercare and referral of patients found to have alcohol problems are also discussed.

Patients with alcohol problems in the emergency department, part 1: improving detection. SAEM Substance Abuse Task Force. Society for Academic Emergency Medicine.

Medical and social problems related to alcohol use are frequently seen in the ED. Often, the tempo of emergency medicine practice seems to preclude assessment beyond that required by the acute complaint. However, detection of ED patients with alcohol problems can occur using brief screening tools. This article was developed by members of the SAEM Substance Abuse Task Force, and describes screening tools that have been used successfully to identify at-risk and dependent drinkers. Their brevity, reproducibility, and accuracy vary somewhat, but screening can be realistically performed in the busy ED setting. The early detection of patients with alcohol problems would provide the opportunity for early intervention, and may reduce subsequent morbidity and mortality in this patient population.

Stimulation-associated changes in frog neuromuscular junctions. A quantitative ultrastructural comparison of rapid-frozen and chemically fixed nerve terminals.

The ultrastructural effects of stimulation and subsequent rest were measured in frog neuromuscular junctions preserved by rapid-freezing and freeze-substitution, a method that minimizes fixation-associated membrane rearrangements. The effects were compared to those measured in junctions preserved by aldehyde fixation in order to identify artifacts attributable to the method of preservation. Effects of stimulation previously observed in tissue preserved by aldehyde fixation were evident in both the rapid-frozen and aldehyde-fixed neuromuscular junctions in the present study. Synaptic vesicles were reduced in number and cisternal profiles were increased. However, the sizes and shapes of the cisternae differed with the method of preservation. In addition, it was found that mitochondria underwent a change in shape with stimulation. This was accompanied by swelling in the fixed preparations, but not in the rapid-frozen ones. Fixation after stimulation also produced swelling of the nerve terminals, a stimulation-associated change not evident in preparations that were preserved by rapid-freezing. After stimulation and 60 min of rest, nerve terminals showed recovery towards control morphology, evidence that the effects of the stimulation parameters used in the study were reversible. This study, utilizing rapid-frozen material, confirms previous reports based on chemically fixed tissue that stimulation reduces the number of synaptic vesicles and increases the number of cisternae. The findings are in accord with the hypotheses of exocytotic neurotransmitter release and local recycling of synaptic membrane. In addition, the study emphasizes that accurate quantitative assessments of membrane redistribution in active secretory systems cannot depend on chemically fixed tissues. It also shows that mitochondria are susceptible to radical distortion by aldehyde fixatives, and that the degree of susceptibility differs with the physiological state of the tissue.