Unmined Sites Research Articles

Mycobiota of revegetated post‐mining and adjacent unmined sites 10 years after mining decommissioning

Although overlooked in post‐mining rehabilitation, soil mycobiota constitute an important fraction of biodiversity, playing pivotal functions in soil that contribute to the revegetation process and soil stability in post‐mining environments. Evaluating the rehabilitation progress requires comparing it, when possible, with a reference site, preferably identical or similar to pre‐mining characteristics. Here, we investigated the mycobiota from a reference site, comparable to pre‐mining characteristics, and a post‐mining revegetated site 10 years after decommissioning and revegetation, during rainy and dry seasons. We combined the metabarcoding approach with functional traits from fungal operational taxonomic units and complemented our results with traditional techniques for arbuscular mycorrhizal fungi (AMF) surveys using spore morphology and mycorrhizal colonization. Our findings demonstrated that the composition of the fungal community exhibited more differences between the two sites studied than the intra‐annual periods assessed, even though the sites were under the same climatic conditions, spatially nearby, and without barriers between them. The mycobiota composition displayed differences between sites from phylum to genus levels. However, the predictive trophic modes (pathotrophs, saprotrophs, and symbionts) were equivalent in the two sites. All roots of plants assessed had AMF colonization, and AMF spore densities were similar. While many fungal taxa were present at both sites, the spatial connectivity between both sites was insufficient for equivalence of fungal community structure and composition. Differences in chemical and physical soil characteristics may have shaped the fungal communities. This study highlights the need to comprehend the fungal community from mining environments, considering concepts of landscape connectivity.

Assembly of heterotrophic communities during spontaneous succession in quarries: invertebrates model groups and macromycetes

Quarrying has a crucial impact on the environment, but it could enhance species diversity. Mining sites represent important refuges for countless species disappearing from homogenous landscapes. Our study focused on assemblages of heterotrophic communities such as moths (Lepidoptera), carabid beetles (Coleoptera: Carabidae), spiders (Araneae), and macromycetes (fungi: Basidiomycota, Ascomycota) in an active part of kaolin quarries and their immediate surroundings in the Pilsen region, Czech Republic. We compared differences between mined and unmined sites, sites with spontaneous succession and sites with replanted pine trees. In total, we recorded 178 moth, 63 spider, 27 carabid beetle, and 81 macromycetes species, including 21 Red‐listed species. The moths, carabid beetles, and macromycetes tended to inhabit unmined sites; on the contrary, open habitat spiders preferred open sites with replanted pine trees. Based on the life history traits analyses, moth species feeding on forbs and grasses prevail at the active part of kaolin quarries, where higher plant diversity was detected. Large body carabid beetles such as Carabus spp. favored unmined sites, as well as macromycetes with long‐lived fruit bodies. Open habitat and xerophilous spiders inhabited the replanted sites by pine trees where the sparse vegetation was obvious. Our results indicated that groups with radically different life histories such as moths, carabids, and macromycetes may react to mining remarkably similarly, although spiders, despite sharing predatory habits with the majority of carabids, reacted differently.

Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America

In Suriname, mercury (Hg) use has recently increased because of gold mining, which has put fish-reliant communities (e.g., Indigenous and Tribal) at risk of enhanced Hg exposure through the riverine fish these communities consume. To quantify how the magnitude of these risks change according to location and time, we measured total mercury (HgT) in fish at sites downstream and upstream of an artisanal and small-scale gold mining (ASGM) operation in 2004–2005 and in 2017–2018. We tested whether fish HgT burdens over dynamic ranges were increased. Surprisingly, our findings did not support broadly increased fish Hg burden over time or that proximity to ASGM was diagnostic to fish HgT-burden. Subsequently, we elected to test the HgT stable isotope ratios on a set of freshly collected 2020 fish to determine whether differences in Hg source and delivery pathways might cofound results. We found that remote unmined sites were more susceptible to gaseous elemental Hg deposition pathways, leading to enhanced risk of contamination, whereas ASGM proximate sites were not. These results highlight that elemental mercury releases from ASGM practices may have significant impact on fish-reliant communities that are far removed from ASGM point source contamination.

Changes of nutrients and microbial communities in recovery process of abandoned rare earth tailings

Rare earth element (REE) mining has wrought severe ecosystem destruction, particularly in the loss of carbon (C), nitrogen (N), and phosphorus (P). Furthermore, its effects on nutrient recovery characteristics and associated microbial abundance are still poorly understood. In this study, an investigation was conducted to determine C, N, and P recovery patterns and microbial communities in abandoned REE mining tailings with different abandoned durations of 1.5 (1.5-Y), 7 (7-Y), 10 (10-Y), and 14 (14-Y) years and at an unmined site (the control group) in Jiangxi Province, China. Longitudinal tailing delamination at each site was investigated in 0–15 (layer 1) and 15–30 (layer 2) cm tailing layers. During the abandoned duration of REE tailings, C and P in layer 1 continued to recover from 1.62 to 8.51 g kg-1 and from 0.71 to 1.94 g kg-1, respectively; N losses of 0.60 and 0.22 g kg-1 occurred at the 1.5-Y and 10-Y sites, while N in layer 1 slightly increased at the 14-Y site. Mesorhizobium, Methylosinus, Bradyrhizobium, Pseudomonas, and Azospirillum were dominant bacteria at the 14-Y site and in the control. The relative abundances of N-fixing bacteria Mesorhizobium (32.94%), Sinorhizobium (0.24%), Frankia (0.71%), and Burkholderia (2.38%) at the 14-Y site were 1.33–3.97 times those in the control (24.19%, 0.18%, 0.32% and 0.60%, respectively), which was helpful for tailing N recovery. At the 14-Y site, Tylospora (50.24%), Luellia (11.02%), Tomentella (6.94%), and Chaetomium (4.34%) were the dominant fungal genera, while Tylospora (56.93%), Suillus (11.45%), and Penicillium (6.78%) predominated in the control. The relative abundance of the P-dissolving fungus Aspergillus at the 14-Y site (0.42%) was 4.2 times that in the control (0.1%), which may lead to the improved tailing P solubility. At the 14-Y site, woody plants such as Pinus massoniana and native pioneering herbs and ferns such as Dicranopteris dichotoma and Nephrolepis auriculata probably invaded from adjacent areas. This study unraveled the natural restoration of plant and microbial communities along with soil nutrient changes in abandoned REE tailings, thus providing a novel insight into ecological recovery and restoration after mining.

Decoding Chambal River Shoreline Transformations: A Comprehensive Analysis Using Remote Sensing, GIS, and DSAS

Illegal sand mining has been identified as a significant cause of harm to riverbanks, as it leads to excessive removal of sand from rivers and negatively impacts river shorelines. This investigation aimed to identify instances of shoreline erosion and accretion at illegal sand mining sites along the Chambal River. These sites were selected based on a report submitted by the Director of the National Chambal Sanctuary (NCS) to the National Green Tribunal (NGT) of India. The digital shoreline analysis system (DSAS v5.1) was used during the elapsed period from 1990 to 2020. Three statistical parameters used in DSAS—the shoreline change envelope (SCE), endpoint rate (EPR), and net shoreline movement (NSM)—quantify the rates of shoreline changes in the form of erosion and accretion patterns. To carry out this study, Landsat imagery data (T.M., ETM+, and OLI) and Sentinel-2A/MSI from 1990 to 2020 were used to analyze river shoreline erosion and accretion. The normalized difference water index (NDWI) and modified normalized difference water index (MNDWI) were used to detect riverbanks in satellite images. The investigation results indicated that erosion was observed at all illegal mining sites, with the highest erosion rate of 1.26 m/year at the Sewarpali site. On the other hand, the highest accretion was identified at the Chandilpura site, with a rate of 0.63 m/year. We observed significant changes in river shorelines at illegal mining and unmined sites. Erosion and accretion at unmined sites are recorded at −0.18 m/year and 0.19 m/year, respectively, which are minor compared to mining sites. This study’s findings on the effects of illegal sand mining on river shorelines will be helpful in the sustainable management and conservation of river ecosystems. These results can also help to develop and implement river sand mining policies that protect river ecosystems from the long-term effects of illegal sand mining.

Mines to forests? Analyzing long‐term recovery trends for surface coal mines in Central Appalachia

Mountaintop removal mining, and other surface mining operations have severe, large‐scale impacts on the communities and ecosystems of Appalachia. The impact of this disturbance surpasses that of other land clearing events, such as fire or timber harvesting; mines remove both established vegetation and soil, but also alter landscape topography. The Surface Mining Control and Reclamation Act legally mandates restoration of former mines after the end of mining activity, yet the long‐term outcomes of restoration efforts across Central Appalachia are unknown. We conducted the first regionwide analysis of the lands mined between 1985 and 2015 in Central Appalachia, and explore post‐mining ecological trajectories. Pairing mine‐footprint and remote sensing data, we characterize the vegetation trends and site health at 71,140 mine sites across Central Appalachia. We use first order autoregressive models to describe the rates of recovery, expected long‐term ecological state, and probability of recovery to reference state for former mines. We found that only 7.9% of sites recover to 95% of the forest reference condition in all remote sensing indices. Overall only 0.10% of sites have a 95% probability of reaching or exceeding reference forests in all remote sensing indices. While much of these mined lands are intentionally not being reforested, 19% of mines in Kentucky, 81% of mines in Virginia, and 46.5% of mines in West Virginia have declared forestry as the primary land use for post‐mining operations. Our results indicate that post‐mining forests are not recovering to a level that is consistent with average forest conditions in similar unmined sites.

Rehabilitating open-cut coal mine spoil for a pasture system in south east Queensland, Australia: Abiotic soil properties compared with unmined land through time

Rehabilitation of mined land intends to support food and biomass production, with open cut mines required to return the land to a safe, stable and productive state in Queensland, Australia. The aim of this investigation was to assess the potential for soil that was previously farmed, then mined and rehabilitated to support pasture for commercial cattle production. The study was focussed on abiotic properties of the rehabilitated soils, in comparison to properties of a range of unmined soil profiles supporting pastures within the immediate vicinity. Three hypotheses were tested: 1) the abiotic properties of rehabilitated soils would fall within the range of those from nearby unmined soils; 2) that rehabilitated soils would support viable pasture production; and 3) that the mine-spoil would restrict root function. The mine was situated near Acland, Queensland, with rehabilitated land sown to pasture 1, 3 and 6 years prior to the initiation of the study in 2013. The investigation followed these rehabilitated sites, in comparison to a Control site, and 18 proximal unmined sites, through a five year period. All sites were used to support cattle grazing, with soil nutrients, structural condition and pasture growth (8 sites) monitored. Evidence from pasture production and root exploration obtained through soil pit investigations demonstrated that the mine spoil was capable of supporting root growth beyond the replaced soil layer. There were few differences between the Control and rehabilitated sites with regard to benefits or constraints to pasture production, with exception that two rehabilitated sites had simillar or higher plant-available phosphorus and nitrogen. It was concluded that: 1) abiotic properties of rehabilitated soils fell within the range of unmined soils; 2) viable pasture production was achieved from the rehabilitated sites; and 3) both the replaced soil layer and the mine spoil supported root exploration and pasture production.

Sustainability of beef production from brigalow lands after cultivation and mining. 1. Sown pasture growth and carrying capacity

Context New Acland coal mine in south-eastern Queensland is seeking to rehabilitate mined land to pastures that are safe, stable and sustainable for beef production. Little is known of the productivity and sustainability of grazing previously mined land in the Darling Downs study region. Additionally, information is required to specify management guidelines for sustainable grazing of regional land types retired from cultivation. Aims Identify pasture growth characteristics, rainfall use efficiencies and long-term carrying capacities of subtropical sown pastures established on lands rehabilitated after open-cut coal mining in comparison to sown pastures established on un-mined but previously cultivated lands. Methods Pasture growth and quality (% nitrogen) were observed using the Swiftsynd methodology in ungrazed exclosures with three sites on rehabilitated lands of the Acland Grazing Trial over a 5-year period (2014–2018), and 13 sites on unmined lands over periods of 2–5 years providing data for modelling pasture growth. Key results Peak pasture yield (TSDM for autumn harvests) averaged for 2017 and 2018 was greater (P < 0.1) on rehabilitated sites than unmined Poplar Box land type sites (5957 and 2233 kg/ha respectively) but similar to Brigalow Uplands and Mountain Coolibah land type sites (3946 and 3413 kg/ha respectively). Pasture rundown was evident, with pasture N uptake decreasing over 5 years at some sites. Soil mineral N supply (potentially mineralisable N and mineral N) in spring was a useful indicator of N uptake over the following growing season. Simulations using the GRASP pasture growth model for the grazing trial period predicted rainfall use efficiencies of 12.0, 7.0, 9.1 and 4.8 kg/ha.mm rainfall for rehabilitated sites and unmined sites on Brigalow Uplands, Mountain Coolibah and Poplar Box land types respectively. Long-term carrying capacities based on estimates of long-term median pasture growth and 30% utilisation were 4.39, 3.58 and 5.92 ha/adult equivalent respectively for the unmined land types, and 2.45 ha/adult equivalent for the rehabilitated lands. Conclusions Rehabilitated land can be as productive as unmined but previously cultivated land. Implications Grazing management plans for sustainable management of mined and unmined lands can be developed using data from the present study. The plans will assist with the transition of rehabilitated lands to commercial agriculture.

Sustainability of beef production from brigalow lands after cultivation and mining. 3. Pasture rundown, climate and grazing pressure effects

Context The Acland Land System overlying the Walloon sandstone coal deposits in southern Queensland is generally marginal for cropping but well suited to grazing, and thus cultivated land is commonly returned to pasture. Rehabilitation of these lands after open-cut coal mining seeks to be safe, stable and self-sustaining to satisfy requirements for ecologically sustainable development. Aims The present paper evaluates the sustainability and economic viability of beef production on (a) lands retired from cultivation and then rehabilitated with sown pastures after open-cut coal mining at the New Acland mine site, and (b) similar nearby pasture lands that were not mined but were also retired from cultivation. Methods The GRASP grazing systems model was modified and calibrated with short-term (5-year) grazing trial data (soil, pasture and cattle observations), and then used with long-term (60-year) weather data to estimate effects of land type, pasture rundown, climate and grazing pressure on productivity and economic returns. The productivity of three rehabilitated sites and 15 unmined sites were evaluated, including pastures on six commercial properties. Key results Estimates of long-term mean annual growth of pastures on unmined lands retired from cultivation on three land types (Mountain Coolibah, Brigalow Uplands and Poplar Box) were 3398, 2817 and 2325 kg/ha respectively. Pasture growth was greater on rehabilitated lands; 3736 kg/ha on the site most typical of rehabilitated lands and a mean of 4959 kg/ha across three sites. Seasonal conditions had large effects on cattle liveweight gain (133–213 kg/head per year during the trial); however, pasture growth was the main driver of beef production and economic returns per hectare. In GRASP, potential nitrogen uptake was used to influence key pasture growth processes and accounted for 64% of variation in observed annual growth. The short-term lift and subsequent rundown in productivity typically associated with sown pastures was estimated to have increased mean annual pasture and cattle productivity during the 2014–2018 trial period by up to 17% and 25% respectively. Estimates of long-term mean annual beef production and economic returns for the unmined lands were less than estimated for rehabilitated lands and were 139 kg/head.year (45 kg/ha.year) and AU$154/adult equivalent. Conclusions Rehabilitated lands were found to be sustainable for beef production at grazing pressures up to 30% utilisation of annual pasture growth, and comparable with grazing systems on native and sown pastures in good condition. Pastures on unmined lands retired from cultivation had reduced productivity. Implications Overgrazing is a significant and on-going residual risk to sustainable production. Grazing regimes need to continually adjust for changes in novel landscapes, pasture condition and climate. The methods used in the present study could be applied more generally.

Effects of stone mining on woody plant species diversity and selected soil properties in northern Ethiopia

BackgroundStone mining is one of the main livelihood activities in areas close to major cities in Ethiopia. Mining tends to make a notable impact on woody plant species and soil properties. Information regarding the effect of stone mining on woody plant species diversity and soil properties is limited in Ethiopia. It is also less known how people perceive the impact of stone mining on existing natural resource in the watershed after mining. Therefore, this paper analyzed the effect of stone mining on woody plant species diversity, selected soil properties and perception of nearby community on mining in northern Ethiopia.MethodsVegetation and soil sampling were conducted using 6.32 ha sample plots. Samples were randomly selected from mining and adjacent unmined areas. Species abundance, density, basal area, selected soil physical and chemical properties were analyzed. The differences in species diversity and soil physical and chemical properties between the mined and unmined areas were analyzed using independent t test. Household survey was also conducted to assess the view of the local people regarding the effect of mining on ecology.ResultsA total of 35 species representing 19 families in the mining site were recorded while 43 species representing 27 families were recorded in the unmined site. Abundance and density of species were higher in unmined than in mining areas. The most abundant species in the mining and unmined sites were Euclea racemosa subsp. schimperi, Senna singueana, Maytenus arbutifolia, Calpurnia aurea and Buddleja polystachya. Woody species diversity at mining (1.97) was significantly different from that unmined (2.49) site (p = 0.0005). Bulk density significantly varied between the mined (1.9 g cm−3) and unmined (1.38 g cm−3) sites (p < 0.0005). Furthermore, significantly higher TN and AvP was recorded at unmined areas as compared to the mining areas (p < 0.05). Discussion with communities is mandatory before deciding a site for mining. Respondents argued that mining negatively affects the vegetation and other resources that brought devastating effect on the downstream farms. The communities’ were recommended for immediate rehabilitation of abandoned lands to restore it and reduce the negative impact of mining.ConclusionsStone mining causes an adverse impact on plant species and soil physico-chemical properties. Discussion with communities at the planning stage, immediate restoration activities and monitoring are crucial to reduce the negative impacts of stone mining for further sustainable natural resources development and management.

Comparison of Flora of Small-Scale Mined and Unmined-Sites in Dunkwa-East Municipality, Ghana

The impacts of small-scale mining on the vegetal cover as well the livelihoods of communities in mined areas in developing countries such as Ghana are far-reaching. This study assessed the impacts of small-scale mining on flora of conservation and economic significance through quantification of species richness, and species diversity. Mined and unmined sites were chosen in the Dunkwa East Municipality of Ghana. Five belt transects each (200m &amp;times; 200m) were constructed in both sites. Each belt transect was divided into 100 quadrats (20m &amp;times; 20m) and plant species in each of the quadrat were identified in the field and or the herbarium of the School of Biological Sciences, University of Cape Coast. One hundred and fifty seven species distributed in 140 genera and 54 families were identified in the mined area whilst the 209 species identified in the unmined area were in 185 genera and 73 families. Plant families Euphorbiaceae, Rubiaceae and Asteraceae were more diverse whilst Asteraceae, Poaceae and Euphorbiaceae were dominant in the unmined area. In the mined area, however, Poaceae, Euphorbiaceae and Asteraceae were more diverse. Pteridium aquilinum, Tridax procumbens and Waltheria indica in the unmined area and Chromolaena odorata, Sporobolus pyramidalis and Euphorbia hirta in the mined area were the dominant species. Small-scale miming activities have caused reduction in species diversity, richness and economic and commercial values in the area. Higher disturbance of the flora has resulted in more secondary species in the mined area. Restoration is required in the study area.

Microbial community structure and relationship with physicochemical properties of soil stockpiles in selected South African opencast coal mines

ABSTRACT At present, there is no comprehensive soil quality assessment practice for soil stockpiles in the South African coal mining industry. Soil microorganisms and enzymes are suitable indicators for soil quality monitoring. Therefore, this study investigated the microbial community and enzyme (beta-glucosidase and urease) activities in soil stockpiles of opencast coal mines in the coal-rich region of South Africa. Soil stockpiles of three opencast coal mines were sampled at depths of 0–20 cm (‘topsoil’) and >20 cm (‘subsoil’) across three seasons. Beta-glucosidase and urease activities were mostly higher in soil stockpiles than in unmined soils and were significantly influenced (P < 0.05) by the interaction of site and seasonal factors. However, analyses of PCR-denaturing gradient gel electrophoresis (PCR-DGGE) profiles of partial 16S rRNA gene and internally transcribed spacer 2 (ITS2) sequences revealed higher microbial diversity in unmined (reference) soils compared to soil stockpiles across all seasons. Redundancy analysis further revealed that microbial communities of topsoil were not significantly (P > 0.05) influenced by soil properties, whereas microbial communities of subsoils were significantly (P < 0.05) influenced by pH, organic carbon, total nitrogen and phosphorus contents. Furthermore, operational taxonomic units (OTUs) belonging to genera of known phytobeneficial species such as Azomonas, Aureobasidium, Phialocephala, Phoma and Sordariomycetes were detected in these soils. Overall, results suggest that the microbial community structure and diversity observed in stockpiles is impaired (compared to the unmined site), although variations in the microbial community structure of soil stockpiles across seasons are site-specific. The impaired microbial community of stockpiles may have negative implications on soil biological processes driven by microbes; especially those that are critical for nutrient cycling and ecosystem sustainability. More importantly, such alteration in soil biodiversity may impair post-mining land use capability of stockpile soils.

The effects of phytoremediation on soil bacterial communities in an abandoned mine site of rare earth elements

Overexploitation of rare earth elements (REEs) has caused serious desertification and environmental pollution. The ecological restoration of mining areas has attracted increasing attention in China. Soil microbiota is important for successful ecological remediation of abandoned mine land. In this study, soil samples were collected from a restored REE mine site, and the bacterial community composition and diversity were assessed by Illumina high-throughput sequencing targeting the V3-V4 region of the 16S rRNA gene. Microbiota significantly developed in the remediated land. A total of 663,781 effective 16S rRNA gene sequences were obtained, which were classified into 28 bacterial phyla and 3 archaeal phyla. The dominant phyla across all samples (>5% of total effective sequences) were Proteobacteria, Acidobacteria and Firmicutes. Bacterial diversity indices (OTU number, Shannon index and Chao1 index) of the restored soils were higher than those of the tailings and even surpassed those in the unmined site. Redundancy analysis indicated that soil nutrients (soil organic carbon, available phosphorus and total nitrogen) were the dominant factors, followed by soil pH, affecting bacterial community structure. In general, these results suggested that soil amendment and phytoremediation effectively improved the soil environment of the abandoned mine site, which also increased our understanding of the correlation between microbial variation and soil properties in restored REE mine soils.

Assessment of arbuscular mycorrhizal fungal spore density and viability in soil stockpiles of South African opencast coal mines

The symbioses between arbuscular mycorrhizal (AM) fungi and plant roots is essential for nutrient uptake and growth of most vascular plants. Soil condition and management influence the density and viability of arbuscular mycorrhizal fungal (AMF) spores. In this study, AMF spore density and viability in soil stockpiles obtained from three opencast coal mines were assessed. Soil samples were randomly collected from stockpiles and an unmined site at depths of ≤20 cm (topsoil) and >20 cm (subsoil) for enumeration of AMF spores and a mycorrhizal trap culture experiment using maize (Zea mays). Roots of trap-plants were assessed for mycorrhization by classical staining as well as detection of nuclear rRNA gene of the Glomeromycota phylum. Number of AMF spores was highest in topsoil from the unmined site and was significantly (p < 0.05) influenced by site × sampling depth interaction. DNA-based detection revealed that AMF colonisation was mostly associated with topsoil than with subsoil. Five operational taxonomic units (OTUs)/ species related to Paraglomus were identified; however, some of the OTUs were phylogenetically distant from defined Paraglomus species on the basis of sequences in the GenBank database. Overall, results suggest that AMF spore density in stockpiles do not differ from an unmined site, but viability may be influenced by soil depth.

Post-reclamation Age Effects on Soil Physical Properties and Microbial Activity Under Forest and Pasture Ecosystems

ABSTRACTDuring surface mining and subsequent reclamation efforts, physical, chemical, and biological properties of soils are disturbed. A study was conducted to evaluate the effects of age chronosequence on soil physical property and microbial activity in chronosequence reclaimed sites covering successional ages in the ranges 1, 4, 8, 11, and 13 years under forest and pasture ecosystems. The adjacent normal and unmined pasture and forest were used as a control for comparison purposes. The study site was located at the Red Hill Mine in east central Mississippi (approximately 33.3 N latitude and 89 W longitude), which is used by the North America Mining Company, LLC. Soil samples were collected from the reclaimed and unmined sites at 0–15- and 15–30-cm depth and analyzed for selected soil quality indicators. Results indicated that water stable aggregate and infiltration were increased, but soil bulk density and compaction decreased with increasing reclamation age. Soil penetration resistance was greater in the pasture than forest ecosystem. All reclaimed soils had less microbial enzyme activity than an unmined forest ecosystem; however, bacteria population level after 11 years since reclamation was similar to that of unmined forest soils. Soil organic carbon increased with increasing reclamation age strongly correlated with soil physical indicators and appears to be the main driving force during the development of soil physical and biological properties in the humid southeast.

Multi-fractal characteristics of three-dimensional distribution of reconstructed soil pores at opencast coal-mine dump based on high-precision CT scanning

The pore conditions of reconstructed soils can reflect the quality of rehabilitated soils. In this paper, high-resolution and non-destructive computed tomography (CT) images were used to conduct three-dimensional reconstruction of soil pore distribution by scanning soils from the Antaibao Opencast Coal-mine in the Pingshuo mining area, and multi-fractal theory was used to analyze the distribution characteristics of soil pores. The soils were taken from one unmined site, one unrehabilitated site and two rehabilitated sites. All of the unrehabilitated and rehabilitated sites were on the dump platforms using a loess parent material covering, and two rehabilitated sites had the rehabilitation time of 20 a and 23 a, respectively. The three-dimensional distribution of the reconstructed soil pores followed the multi-fractal theory, and the entropy dimension (D1), difference between capacity dimension minus entropy dimension (D0-D1), variation degree of generalized dimension spectra (ΔD), width of singularity spectra (Δα) and symmetry of singularity spectra (Δf) can reflect different aspects of the soil pore distribution characteristics. Compared to unmined soils, the multi-fractal parameters of soil pore distribution (D1, D0-D1, ΔD, Δα and Δf) significantly decreased after mining and dumping, and soil micropores dominated with uniformity. However, D1, D0-D1, ΔD, Δα and Δf had significant increase during rehabilitation, and the pore conditions of rehabilitated soils were improved significantly with increasing rehabilitation time, increasing macropore ratio and becoming heterogeneous.

Geoarchaeological and 3D visualisation approaches for contextualising in-situ fossil bearing palaeokarst in South Africa: A case study from the ∼2.61 Ma Drimolen Makondo

South Africa contains a wealth of palaeokarst deposits that have yielded hominin fossils and Early Stone Age archaeology. Despite the complex nature of deposition within many of these caves there has been a dearth of detailed geoarchaeological studies undertaken on these sites. Many sites in South Africa have been interpreted using an overly simplistic Member System based on simplified sedimentological attributes, rather than chronostratigrahic units. Many of the defined Members thus identify different, but contemporary geological processes occurring in the caves. This has caused serious confusion in reconstructing the life histories of palaeocaves and the ages of the fossil remains interned within them. It is critical to uncover new sites that have not been extensively altered by decades of data collection and destructive mining techniques employed early in their discovery. Although unmined sites present their own problems with regards to extensive colluvium cover and access to fossil-bearing units, analysing strata that is found in-situ enhances overall confidence of interpretations drawn. A wealth of geoarchaeological and 3D visualisation techniques can now be employed to aid in the understanding of cave life histories, as well as their excavation. In this paper we present the first attempt to integrate and publish data from a range of such methods on South African fossil bearing palaeokarst using the newly discovered Drimolen Makondo deposit as a case study. This includes the use of ground penetrating radar, 3D visualisation through photogrammetry and multi-scale 3D scanning, micromophology and petrography, palaeomagnetism, mineral magnetism, synchrotron radiation, electron spin resonance, uranium-lead dating and biochronology. Our analysis has allowed us to successfully uncover the full extent of this new ∼2.61 Ma fossil bearing palaeokarst deposit and to visualise and interpret its chronostratigraphy.

Impacts of artisanal gold mining systems on soil and woody vegetation in the semi‐arid environment of northern Ethiopia

Gold mining is a tremendously important economic activity in rural districts of Ethiopia. We assessed the impacts of artisanal gold mining on soil and woody vegetation in northern Ethiopia. Estimation of soil loss, plant inventory, group discussions and transect studies were used to address the research questions. We employed t‐test to compare woody species and soil loss between mined and unmined sites. Moreover, we ran one‐way ANOVA to compare the average volume of soil loss among the mining sites. The study shows that gold mining removed colossal volumes of soil from the mining landscape with a significant difference among gold mining sites (P ≤ 0.05). Soil loss between the mined and unmined sites was also significant (P ≤ 0.05). Moreover, gold mining destroyed massive tracts of vegetation. Woody species encountered at plot level decreased from artisanal gold mined to unmined sites (P ≤ 0.05). Moreover, dead trees and exposed tree roots were higher in mined than the unmined areas (P ≤ 0.05). This discouraged regeneration and recruitment of woody vegetation. To conclude, gold mining system converted vegetated sites and farmlands into dysfunctional landscape. Therefore, we suggest that combined rehabilitation efforts are required to overcome the challenges of artisanal gold mining on sustainable land management in northern Ethiopia.

Effects of mountaintop removal coal mining on the diversity and secondary productivity of Appalachian rivers

AbstractLand cover change often alters the chemical regime and reduces the diversity of sensitive taxa in downstream aquatic ecosystems. The consistently elevated ionic strength associated with surface coal mines has been implicated in extirpating sensitive taxa throughout many Appalachian streams. We quantified secondary production at three sites spanning a gradient of mining impacts in the Mud River (West Virginia, U.S.A.) by sampling macroinvertebrates monthly from 2012 to 2013. Not only do we observe significant changes in aquatic insect community structure driven by the loss of sensitive taxa in mined watersheds, but we show that these losses translate directly to depressed biomass throughout the year becoming most apparent when pollutant concentrations rise during summer baseflow. These distinct seasonal patterns result in threefold decreases in total insect production and EPT production ∼1‐km downstream of an unmined reach. Farther downstream, where pollutant concentrations are much higher, total annual productivity is similar to the unmined reach, but suffers from a 31% loss of taxa comprising production and altered timing of that production. Mayflies were the insects most notably affected by the chemical alteration. Whereas mayflies accounted for ∼14% of total production in our upstream, unmined site, they only accounted for 0.2% of production at the most impacted site. We conclude that elevated ionic strength depresses insect production by preventing sensitive taxa from completing their life cycles in mining‐impacted streams. Because surface coal mining dominates the Central Appalachian landscape, such altered production patterns are likely a common landscape feature impacting regional food webs.

Variations in pore distribution of reconstructed soils induced by opencast mining and land rehabilitation based on computed tomography images

ABSTRACTOpencast coal mining is an anthropogenic activity that changes the antecedent soil profile, and it was important to understand the distribution characteristics of soil pore and then select suitable land rehabilitation measures. To better quantify the pore distribution characterization of reconstructed soils in opencast coalmine dumps, high-resolution and non-destructive computed tomography (CT) method was used to study the effect of opencast coal-mining and land rehabilitation on the soil pore distribution by scanning soils from the Antaibao Opencast Coal-mine in China. The soils were taken from the dump platforms with different rehabilitation time and an unmined site. ImangeJ 2 was used to process the scanned images and the soil pore densities and porosities of different pore sizes were used to analyze the distribution characteristics of soil pore. Opencast mining activities decreased soil pore density and soil porosity, especially in macropores. Compared to unmined soils, the total porosity of the non-rehabilitated soils reduced by 25.0%, 20.5%, 17.7% at the depths of 0–25, 25–50, 50–75 cm, respectively. Vegetation rehabilitation should be used to develop soil pore structure and improve the proportion of different pore sizes.