CASE REPORT | doi:10.20944/preprints201806.0117.v1
Subject: Earth Sciences, Environmental Sciences Keywords: sulfur; reclamation; acid mine drainage; salinity; soil contamination
Online: 7 June 2018 (11:21:57 CEST)
Sulfur contamination of topsoil, spatial distribution of contamination and surface water chemistry were investigated on an area of over 200 ha of a new forest ecosystem. Common birch and Scots pine growth reaction, vitality and nutrients supply, as well as wood small-reed (Calamagrostis epigejos (L.) Roth) chemical composition were assayed. The chemistry dynamics of soil leaching and the sulfur load leached from the sulfur contaminated soil-substrates were analyzed. The remediation effect of the birch and pine litter was assayed in an experiment under controlled conditions. It was found that reclamation was effective in a majority of the post-mining site, however hot-spots with sulfur contamination reaching even 45,000 mg kg-1, pH <2.0, and EC 6,500 µS cm-1 were reported. Surface waters typically displayed elevated concentrations of sulfate ions (average 935.13 mg L-1), calcium ions (up to 434 mg L-1) and high EC (average 1.795 µS cm-1), which was connected both with sulfur contamination and sludge lime used in neutralization. Wood small-reed was found to be species adapting well to the conditions of elevated soil salinity and sulfur concentration. We noted that an addition of organic matter had a significant impact on the chemistry of soil solutions but did not indicate in short term experiment a remediation effect by increased sulfur leaching.
ARTICLE | doi:10.20944/preprints202001.0377.v1
Subject: Earth Sciences, Geophysics Keywords: ERT method; regression model; tailings pond; heavy metal; reclamation
Online: 31 January 2020 (05:04:37 CET)
Legacy mining industry has left a large number of tailings ponds exposed to water and wind erosion that causes serious environmental and health problems. Prior to rehabilitation actions a deep sampling of the materials infilling the pond used to be necessary. Thus, the primary objective of this study is to demonstrate the usefulness of the Electrical Resistivity Tomography (ERT) method as a non-invasive tool to determine the physicochemical composition of mine tailings ponds, enabling more efficient and low-cost surveys. To achieve this objective, three ERT profiles and three boreholes in each profile were carried out, from each borehole three waste samples from differents depths were collected and a geochemical characterization of the samples was carried. In order to estimate the composition of the infilling wastes in tailing ponds from electrical resistivity measures, several regression models were calculated for different physicochemical properties and metal concentrations. As a result, a high resistivity area was depicted in profiles G2 and G3 while a non-resistive area (profile G1) was also found. Relationships among low resistivity values and high salinity, clay content and high metal concentrations and mobility were established. Specifically, calibrated models were obtained for electrical conductivity, particles sizes of 0.02-50 µm and 50-2000 µm, total Zn and Cd concentration, and bioavailable Ni, Cd and Fe. Therefore, the ERT technique could be considered as a useful tool for mine tailings ponds characterization, and it can be used to estmate some physicochemical properties and metal concentrations of this mine waste.
ARTICLE | doi:10.20944/preprints202107.0027.v1
Subject: Arts & Humanities, Anthropology & Ethnography Keywords: Beaufort West; drought; Gamka Dam; boreholes; water load-shedding; reclamation plant; municipality; bottled water
Online: 1 July 2021 (13:17:32 CEST)
Increasing and prolonged droughts have become a feature of the South African environmental landscape. This article investigates the sustainability of water procurement to the rural town of Beaufort West and the reasons for the town’s water provision crises during the droughts of 2009-2011 and 2017-2019. Innovative solutions were reached to alleviate the serious water-shortages during these droughts. Data to illustrate population increases and precipitation decreases, which impacted on the town’s water resources, was collected from census records of Statistics South Africa and from the Department of Water and Sanitation, respectively. A number of risk factors contributed to the town’s water crises, e.g. unsustainable water extraction at times of serious droughts, poor water monitoring, metering and attention to leakages, an expansion of informal settlements within the municipal boundaries of Beaufort West, as well as annual rainfall patterns that became increasingly unpredictable. The article concludes that water resource development had not kept pace with demand, therefore water infrastructure should be built with enough capacity to cope with regular dry periods. Equilibrium should be reached between the water expectations of the community and water availability to avoid future social instability in water-stressed towns such as Beaufort West.
ARTICLE | doi:10.20944/preprints201711.0019.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Mining; Mine reclamation; Land cover change; Vegetation health; NDVI Post-mining; SMA; Random forest classification; Remote Sensing
Online: 2 November 2017 (15:01:03 CET)
Mining for resources extraction may lead to several geological and associated environmental changes due to ground movements, collision with mining cavities and deformation of aquifers. Geological changes may continue in a reclaimed mine area, and the deformed aquifers may entail a breakdown of substrates and an increase in ground water tables, which may cause surface area inundation. Consequently, a reclaimed mine area may experience surface area collapse, i.e. subsidence, and degradation of vegetation health. Thus, monitoring short-term landscape dynamics in a reclaimed mine area may provide important information on the long-term geological and environmental impacts of mining activities. We studied landscape dynamics in Kirchheller Heide, Germany, which experienced extensive soil movement due to longwall mining without stowing, using Landsat imageries between 2013 and 2016. A Random Forest image classification technique was applied to analyse land-use and land-cover dynamics and the growth of wetland areas was assessed using a Spectral Mixture Analysis (SMA). We also analyzed the changes in vegetation health using a Normalized Difference Vegetation Index (NDVI). We observed a 19.9% growth of wetland area within the four years with 87.2% of growth in the coverage of two major waterbodies in the reclaimed mine area. NDVI values indicate that 66.5% of the vegetation of the study area was degraded due to changes in ground water tables and surface flooding. Our results inform environmental management and mining reclamation authorities about the subsidence spots and priority mitigation areas from land surface and vegetation degradation in Kirchheller Heide.