Tracing sources and fate of zinc in a mining-impacted river catchment: insights from flow measurements, synoptic sampling, and zinc isotopes

This paper reports on the comprehensive monitoring of the Rookhope Burn catchment in the Weardale valley, northern Pennines (Uk), which has been subject to lead, zinc, and fluorspar mining for over two centuries. Zinc is the major contaminant in surface waters, exceeding the Environmental Quality standard value for salmonid fish. synoptic flow monitoring and water sampling have been carried out, including both inflow and instream sampling points along the Rookhope Burn, with the purpose of tracing both point and diffuse sources of Zn throughout the catchment. The Zn load profile suggests an important role for Zn-rich groundwater contributions to the stream bed and has also established the existence of Zn sinks. Evidence from hyporheic zone sampling suggests Zn reaction or surface complexation with Mn oxide surfaces forming on stream bed sediments as a potential mechanism responsible for the observed metal attenuation. Current work is focused on testing the potential of Zn isotopes to fingerprint sources and pathways of Zn in the aquatic system. Preliminary results show significant variation in the stream water Zn isotopic signature from the headwaters to the base of the catchment

The Hyporheic Zone

This chapter introduces the key concepts of the hyporheic zone. It considers the research context in terms of the Water Framework Directive and the breadth of literature associated with the hyporheic zone. The interplay between hydrological, chemical and biological processes is explained, and a range of different approaches to field sampling and monitoring are described. A framework for considering the factors contributing to the conceptualisation of the hyporheic zone is presented, with an emphasis on the importance of understanding streambed sediments and their architecture to assess hydraulic functioning and modelling of the hyporheic zone. The hyporheic zone in karst catchments is also given specific consideration. Returning to the theme of linked hydrological, biological and chemical processes, the results of two case studies demonstrate the value of integrating hydrological measurements with geochemistry in order to elucidate hyporheic zone functioning

Conceptual models of Witbank coalfield, South Africa : Earth observation for monitoring and observing environmental and societal impacts of mineral resources Exploration and Exploitation, CEC FP7 Project EO-MINERS, Deliverable D3.1-2

This report presents the work undertaken as part of the EO MINERS WP3 - project task 3.1. “Site Specific Available Data Collection” and develops a conceptual site model (CSM) for the Witbank coalfield, South Africa and for Bank Colliery, South Africa which has been selected to demonstrate the automated time-lapse electrical resistivity monitoring (ALERT) system of a leachate plume. The report presents the available information regarding known apparent environmental impacts. This information is derived from a literature review and from the findings of surveys conducted as part of work package WP1. Additionally the principal socio-economic impacts defined by WP1 have been presented. It goes on to consider the environmental factors that influence the transport of contaminants from the source to the exposed individuals or environmental receptors, through identified potential exposure pathways, describing the source- pathway-receptor interactions through two conceptual site models (CSMs), one for the Witbank Coal Mining region and the other for Bank Colliery. A CSM for the socio-economic impacts has also been attempted. Examining the CSM results in the identification of data gaps and information needed for a full environmental assessment of mining in Witbank and provides the rational for EO selection. Present and past coal mining in Witbank is associated with a number of environmental problems, including: acid mine drainage (AMD) derived from the oxidation of pyrite in the coal, specific contaminants including potentially harmful metals and arsenic (which occur in the mining environment and in dust associated with both the operation of the mines and the transport of the coal) and ground gases that are both naturally occurring and a consequence of self-combustion of the coal and waste dumps. A wide range of ecological and socio-economic impacts result from these impacts, including the impacts on land value and agriculture. Additional problems include ground subsidence due to pillar collapse, which has further consequences on the migration of AMD and self combustion. The CSMs have been used to identify the key direct or indirect indicators of mining impacts and an assessment of the potential to monitor these using Earth Observatory (EO) assessments has been made. The majority of the indicators lend themselves to EO assessment in one form or another (Table 7)

Catchment-scale assessments of the effects of abandoned metal mines on groundwater quality and stream ecology

This paper presents an overview of a British Geological Survey catchment-scale research project designed to quantify catchment-derived metal loading on surface water quality. This work is focused on the Rookhope Burn, a tributary of the River Wear in the North Pennines, UK. The river has been identified in the Water Framework Directive (WFD) River Basin Management report as being at risk of failing to achieve Good Status due to mines and minewater pressures. Although geologically relatively simple, the catchment is hydrogeologically complex in that it comprises an area of entrenched karst, characterised by Lower Carboniferous Limestone exposed in the base of valleys overlain by Namurian strata, comprising interbedded shales, sandstones and limestones, which are capped by drained blanket peat. Metal loadings in this catchment result from lead and zinc mineralization and its historic exploitation and processing, which have resulted in both point source and diffuse impacts within the catchment. There have been three main phases of research: (i) collection of hydrological and water chemistry data to enable loading and mass balance calculations to be undertaken; (ii) development of a conceptual understanding of the hydrology and hydrogeology of the catchment, and (iii) application of the hydrological understanding to more recent baseline monitoring of ecological impacts. This work has identified previously unreported mine and groundwater contributions to the catchment, which may have significant implications for the design of remedial measures in the catchment

Limitations on the role of the hyporheic zone in chromium natural attenuation in a contaminated urban stream

The urban hyporheic zone may offer natural attenuation potential for contaminants. This potential is contaminant-specific and may be spatially and temporally variable. The aim of this study was the assessment of the natural attenuation potential of the hyporheic zone of an urban stream receiving hexavalent chromium (Cr)-rich effluents from the historical land disposal of chromite ore processing residue (COPR) in Glasgow, Scotland. The evidence based approach involved the use of a network of multilevel piezometers for best capturing potential anoxic field conditions and fine-scale spatial gradients in solute concentrations of surface water and porewater. In-situ porewater sampling was integrated with sediment sampling and reach-scale monitoring of stream water quality. The results show a sharp decrease of total dissolved (filtered <0.45 μm) Cr concentrations at the surface water – sediment boundary in all profiles, from Cr mean values of 1100 μg l−1 in surface water to 5 μg l−1 in porewater. Chromium speciation analysis indicates that no Cr(VI) was detectable in the neutral pH, moderately reducing porewater, while it was the dominant species in surface water. Evidence of historical COPR detrital grains contributed to the total Cr concentrations (size fraction <150 μm) up to 8800 mg kg−1 in the streambed sediment. The abundance in the porewater of Fe (mean value = 1700 μg l−1), mainly as Fe(II), a natural electron donor for Cr(VI) reduction to Cr(III), indicates a high natural attenuation potential of the hyporheic zone for downwelling dissolved Cr, through Cr(VI) reduction to Cr(III) and the formation of Cr(III) solids of low solubility. Authigenic Cr-rich rims on particles also documented active Cr precipitation from solution in the fine sediments. Large short-term changes of stream stage and stream water composition were not reflected in the hyporheic conservative (chloride) and reactive solute composition. This result indicates only limited surface water infiltration and suggests that small advective exchange might limit the effectiveness of the hyporheic zone for enhancing Cr surface water quality at the reach-scale. This is supported by further evidence from preliminary surface water quality synoptic sampling which shows only moderate to low downstream decrease in surface water Cr concentrations. The surface water investigation needs to be supported by combined water quality-flow monitoring and to be extended to a wider range of temporal and spatial scales to corroborate the reach-scale findings

Leukoaraiosis, intracerebral hemorrhage, and functional outcome after acute stroke thrombolysis

OBJECTIVE: To perform a systematic review and pooled meta-analysis of published studies to assess whether the presence of leukoaraiosis on neuroimaging before treatment with thrombolysis (IV or intra-arterial) is associated with an increased risk of symptomatic intracerebral hemorrhage (sICH) or poor functional outcome. METHODS: We included studies of patients with acute ischemic stroke, treated with IV or intra-arterial thrombolysis, which assessed functional outcome (3-month modified Rankin Scale [mRS]) or sICH in relation to leukoaraiosis on pretreatment neuroimaging (CT or MRI). We used random-effects models to calculate pooled relative risks (RR) of sICH and poor functional outcome (mRS \u3e /= 2) for any vs no leukoaraiosis (using any rating scale) and for no to mild vs moderate to severe leukoaraiosis (using the Van Swieten or Fazekas Schmidt scale). RESULTS: We identified 15 studies (total n = 6,967). For sICH outcome, the RR was 1.65 (n = 5,551; 95% confidence interval [CI] 1.26-2.16, p = 0.001) with an absolute risk (AR) increase of 2.5% for any leukoaraiosis vs none. The RR was 2.4 (n = 4,192; 95% CI 1.83-3.14, p = 0.001) with an AR increase of 6.2% for moderate to severe vs no to mild leukoaraiosis. For poor functional outcome; the RR was 1.30 (n = 3,401; 95% CI 1.19-1.42, p = 0.001) with an AR increase of 15.4% for any leukoaraiosis vs none. The RR was 1.31 (n = 3,659; 95% CI 1.22-1.42, p = 0.001) with an AR increase of 17.5% for moderate to severe vs no to mild leukoaraiosis. No statistical heterogeneity was noted for any of the analyses. CONCLUSIONS: Leukoaraiosis presence and severity are consistently associated with an increased risk of sICH and poor functional outcome after IV or intra-arterial thrombolysis for acute ischemic stroke

Small vessel disease and biomarkers of endothelial dysfunction after ischaemic stroke

Abstract Introduction: Although pathogenesis of small vessel disease is poorly understood, increasing evidence suggests that endothelial dysfunction may have a relevant role in development and progression of small vessel disease. In this crosssectional study, we investigated the associations between imaging signs of small vessel disease and blood biomarkers of endothelial dysfunction at two different time points in a population of ischaemic stroke patients. Patients and methods: In stroke patients treated with intravenous thrombolysis, we analysed blood levels of von Willebrand factor, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and vascular endothelial growth factor. Three reviewers independently assessed small vessel disease features using computed tomography. At baseline and 90 days after the index stroke, we tested the associations between single and combined small vessel disease features and levels of blood biomarkers using linear regression analysis adjusting for age, sex, hypertension, diabetes, smoke. Results: A total of 263 patients were available for the analysis. Mean age (SD) was 69 (13) years, 154 (59%) patients were male.We did not find any relation between small vessel disease and endothelial dysfunction at baseline. At 90 days, leukoaraiosis was independently associated with intercellular adhesionmolecule-1 (b¼0.21; p¼0.016) and vascular cell adhesionmolecule- 1 (b¼0.22; p¼0.009), and lacunes were associated with vascular endothelial growth factor levels (b¼0.21; p¼0.009) whereas global small vessel disease burden was associated with vascular endothelial growth factor (b¼0.26; p¼0.006). Discussion: Leukoaraiosis and lacunes were associated with endothelial dysfunction, which could play a key role in pathogenesis of small vessel disease

Unbalanced metalloproteinase-9 and tissue inhibitors of metalloproteinases ratios predict hemorrhagic transformation of lesion in ischemic stroke patients treated with thrombolysis: Results from the MAGIC study

Background Experimentally, metalloproteinases (MMPs) play a detrimental role related to severity of ischemic brain lesions. Both MMPs activity and function in tissues reflect the balance between MMPs and tissue inhibitors of metalloproteinases (TIMPs). We aimed to evaluate the role of MMPs/TIMPs balance in the setting of rtPA treated stroke patients Methods Blood was taken before and 24-hours after rtPA from 327 patients (mean age 68 years, median NIHSS 11) with acute ischemic stroke. Delta median values of each MMP/TIMP ratio [(post rtPA MMP/TIMP-baseline MMP/TIMP)/(baseline MMP/TIMP)] were analyzed related to symptomatic intracranial hemorrhage (sICH) according to NINDS criteria, relevant hemorrhagic transformation (HT) defined as hemorrhagic infarction type 2 or any parenchimal hemorrhage, stroke subtypes (according to Oxfordshire Community Stroke Project) and 3-month death. The net effect of each MMP/TIMP ratio was estimated by a logistic regression model including major clinical determinants of outcomes Results Adjusting for major clinical determinants, only increase in MMP9/TIMP1 and MMP9/TIMP2 ratios remained significantly associated with sICH (odds ratio [95% confidence interval], 1.67 [1.17 – 2.38], p = 0.005; 1.74 [1.21 – 2.49], p=0.003 respectively). Only relative increase in MMP9/TIMP1 ratio proved significantly associated with relevant HT (odds ratio [95% confidence interval], 1.74 [1.17 – 2.57], p=0.006) with a trend towards significance for MMP9/TIMP2 ratio (p=0.007).Discussion Our data add substantial clinical evidence about the role of MMPs/TIMPs balance in rtPA treated stroke patients. These results may serve to generate hypotheses on MMPs inhibitors to be administered together with rtPA in order to counteract its deleterious effect

Somatic mutations of thymic epithelial tumors with myasthenia gravis

BackgroundThymic epithelial tumors are rare malignant neoplasms that are frequently associated with paraneoplastic syndromes, especially myasthenia gravis. GTF2I is an oncogene mutated in a subgroup of thymomas that is reputed to drive their growth. However, for GTF2I wild-type tumors, the relevant mutations remain to be identified.MethodsWe performed a meta-analysis and identified 4,208 mutations in 339 patients. We defined a panel of 63 genes frequently mutated in thymic epithelial tumors, which we used to design a custom assay for next-generation sequencing. We sequenced tumor DNA from 67 thymomas of patients with myasthenia gravis who underwent resection in our institution.ResultsAmong the 67 thymomas, there were 238 mutations, 83 of which were in coding sequences. There were 14 GTF2I mutations in 6 A, 5 AB, 2 B2 thymomas, and one in a thymoma with unspecified histology. No other oncogenes showed recurrent mutations, while sixteen tumor suppressor genes were predicted to be inactivated. Even with a dedicated assay for the identification of specific somatic mutations in thymic epithelial tumors, only GTF2I mutations were found to be significantly recurrent.ConclusionOur evaluation provides insights into the mutational landscape of thymic epithelial tumors, identifies recurrent mutations in different histotypes, and describes the design and implementation of a custom panel for targeted resequencing. These findings contribute to a better understanding of the genetic basis of thymic epithelial tumors and may have implications for future research and treatment strategies