Post-mining Landscapes Research Articles

Content of phenolic compounds in leaves of trees growing on devastated lands at iron waste rock dump

Knowledge about the content of phenolic compounds in tree leaves growing on devastated lands may be important for foresting of the post-mining landscapes and for improving environmental quality in industrial areas. The object of this study was on standpoint of an ecosystem approach to determine the phenolic compounds concentrations in the leaves of the trees that grow naturally on the devastated lands at iron waste rock dump. Petrovsky waste rock dump areas at Kryvyi Rih Iron Ore Mining & Metallurgical District (central part of Ukraine) were chosen for the present research. During 2017–2021, the 5 research plots in the dump’s area and 1 research plot in the background area (natural ecosystems of the Hurivskyi forest, Kirovohradska oblast) were established. The content of phenolic compounds was investigated in the leaves of three woody plants species: silver birch (Betula pendula Roth.), ashleaf maple (Acer negundo L.) and black locust (Robinia pseudoacacia L.). The extracts of leaves were prepared by extraction of 80% isopropanol. The phenols concentration was determined using Folin-Ciocalteu reagent. The absorbance was measured by spectrophotometer at wavelength of 725 nm. The calibration curve was constructed using standard solutions of gallic acid. The phenols concentration was expressed as gallic acid equivalents in milligrams per gram dry weight of plant material (mg GAE * g-1 dw). The results showed that in background area the values for phenolic compounds content vary within minimal limits: from 26,90 to 27,49 mg GAE * g-1 dw in leaves of silver birch, from 17,53 to 18,11 mg GAE * g-1 dw in leaves of ashleaf maple and from 10,98 to 11,65 mg GAE * g-1 dw in leaves of black locust. In all the samples, the concentrations of phenolic in the leaves of silver birch and black locust were generally within natural limits. The concentrations of phenolic in the leaves of ashleaf maple were below the natural levels. According to the leaves analyses, the phenolic compounds content in all woody plants species from all research plots on the devastated lands were statistical significant differences than the reference samples (P < 0,05). The levels of phenolic in samples of ashleaf maple and black locust were found to be greater (P < 0,05) than the background values about 15–65% and 115–165%, respectively. The concentration of phenolic in leaves of silver birch was lower (about 10–28%, P < 0,05) than those values recorded as control. The woody plants species according to resistance to the devastated lands of the Petrovsky waste rock dump were in the following decreasing order: silver birch (Betula pendula Roth.) > ashleaf maple (Acer negundo L.) > black locust (Robinia pseudoacacia L.).

Tree-ring records of surface displacements in a coal-mining subsided region and their links to hypsometric changes and extreme precipitation

Tree-ring records from sites affected by underground mining provide valuable data on the long-term development of subsidence troughs. However, due to complexity of local conditions, it is unclear whether the surface displacements are actually the result of mining operations or shallow landslides caused by extreme rainfall. This paper compares surface movements at two nearby sites in the Upper Silesian Coal Basin (Central Europe) that have been affected by underground coal mining. Dendrogeomorphic data on subsidence-related movements were obtained from 360 increment cores (90 trees) of European larch (Larix decidua Mill.). Subsidence between 1966 and 2013 was calculated from the corresponding digital elevation models and the actual morphometric parameters of the sites were related to tree-ring records. The effect of precipitation on surface displacements was evaluated using logistic regression models incorporating rainfall data from a nearby meteorological station and dendrogeomorphic event years. The subsidence at the edges of subsidence troughs (study sites) between 1966 and 2013 reached 4–9 m, which is relatively low compared to nearby (5 km radius) directly undermined sites with subsidence up to 22 m. Most events were dated to the 1930s, 1970s, 1990s, and late 2000s with a peak of activity in 1973 and other noteworthy events in 1986, 1995, and 2009. Event years at the site with a flatter topography, and more waterlogged and clay soils are well explained by higher triennial precipitation and higher Simple daily intensity index, suggesting a possible influence of near-surface displacements on the chronology of recorded events, whereas the elevated site with step-block topography showed no relationship between precipitation extremes and event years. We concluded that not only the time of mining operation, but also the site-specific conditions are crucial for characterization of surface displacements in the forested post-mining landscape.

Assesment of heavy metals concentration in initial soils of post-mining landscapes in Kryvyi Rih District (Ukraine)

Abstract Assessment of heavy metals content in the initial soils of the post-mining landscapes plays an important role in pollution control, ecological protection, and safe-guarding human health. In this study, the site-specific pedogeochemical background contents of several metals in soils in Kryvyi Rih Iron Ore Mining & Metallurgical District (central part of Ukraine) were determined. The metal concentrations in the soils of Petrovsky waste rock dump were also quantified and were also assessed using indices of pollution. The field sampling was carried out at a depth of 0-10 cm in five plots in dump area and in one plot in control site. The 43 soil samples were collected. The results showed that local background concentrations of heavy metals in soils of studied area decreased in the following order (mg×kg−1): Fe (42 510) > Mn (761.7) > Cr (94.48) > Zn (90.51) > > As (31.85) > Cu (28.10) > Pb (18.73) > Co (16.21) > Sn (4.64) > Mo (0.28) > Cd (0.16). In the initial soils of devastated lands at Petrovsky waste rock dumps the predominance of increased Cd, Co, Fe, Mm, Mo and Sn content and the predominance of decreased As, Cr and Pb content were observed. Based on the mean values of the individual indices of pollution (Pollution index, Geoaccumulation index, Enrichment factor, Contamination factor) can be assumed that in these soils As, Cd, Fe, Mo, Pb and Sn are mostly coming from industrial activities. Co, Cr, Cu, Mn and Zn are mostly related to their natural occurrence in devastated lands. The values of integrated indices of pollution (Nemerow pollution index, Pollution load index, Degree of contaminated, Modified degree of contamination) indicated that the initial soils of post-mining landscapes can be evaluated as no polluted – and extremely heavy polluted.

Assessment of Heavy Metal Pollution Using Forest Species Plantations of Post-Mining Landscapes, Ptolemais, N. Greece

The main purpose of the study was the absorption of heavy metals in the leaves of forest tree species, which were planted in two different plots for forestry use and environmental restoration. Four species were studied Pinus brutia, Robinia pseudoacaccia, Quercus trojana and Fraxinus ornus. Forty-eight leaf samples were collected which consisted of six samples from each species at each plot. The heavy metal concentrations in the leaves were measured for the following nine heavy metals: iron (Fe), copper (Cu), chromium (Cr), nickel (Ni), cadmium (Cd), manganese (Mn), zinc (Zn), cobalt (Co) and lead (Pd). The determinative estimation of metal concentration was carried out in the clear filtrate, using ICP-OES. Statistically significant differences in the concentrations of the heave metals were found among the species, as well as between the two plots. It was only in Robinia peudoacacia’s leaves that the cadmium concentration showed a statistical difference among the other species. The same applied for manganese in Quercus trojana’s leaves and zinc for Pinus brutia. The careful selection and planting of the appropriate forest tree species provides for an overall improvement in the environment in heavy metal polluted sites, such as those resulting from thermal power plants.

Taxonomic and functional diversity of bird communities in mining areas undergoing passive and active restoration in eastern Amazon

The advance of land-use change processes in the Amazon rainforest has modified its natural landscape, resulting in losses of biodiversity and ecological functions. Under this scenario, some reforestation methods have been proposed and tested in degraded areas aiming to reverse environmental damage. We assess the efficiency of three reforestation methods by investigating the taxonomic and functional diversity of birds in a post-mining landscape located in the eastern Brazilian Amazon. We counted birds in 56 sites located in both forest and areas under the process of ecological restoration through natural regeneration, planting seedlings, and nucleation. Species composition and richness differed significantly between forests and areas under recovery. Nucleation showed distinct species composition from planting seedlings or natural regeneration areas, which can be explained by the difference in environmental structure in the areas recovering by this method. Although age did not influence species richness, we observed different species composition between old and young areas that received planting of seedlings. In general, we found no differences in functional diversity and functional richness between the methods of recovery. We conclude that the three recovery strategies evaluated herein showed a similar efficiency. However, it is necessary to consider that perhaps eight years is a short period to observe significant differences in the structure of the areas recovered by the different methods and, consequently, the structure of bird communities. Also, the diversity patterns of the current bird communities located in the post-mining areas were far from those found in forest areas, indicating the need for maintaining long-term recovery programs.

Groundwater-level recovery following closure of open-pit mines

Open-pit mining has increased substantially over the past two decades. Many currently operating open-pit mines are facing the end of mine-life over the next few decades and, increasingly, focus is shifting towards mine-closure planning that provides evidence on available closure options under the given geological, hydro(geo)logical and climatic conditions. This study uses synthetic groundwater modelling to build basic process understanding of closure options and how these will determine the formation of pit lakes. This governs the long-term pit lake water quality and how postmining landscapes may be utilised. Simulations show that the recovery time of postmining groundwater levels increases with decreasing aquifer transmissivity. Final postmining water tables are predominantly controlled by the implemented mine closure options and climatic conditions. The most important decision is, thereby, whether to backfill the pit to above the water table or allow a pit lake to develop. Under moderately transmissive aquifer settings, backfilling of pits leads to rapidly rising groundwater levels within the first decade after mining, with water-table recoveries of above 70%. If mine voids remain unfilled, evaporation from the pit lake surface becomes a governing factor in determining whether the unfilled mine pit becomes a terminal sink for groundwater. Lake levels may remain subdued by several 10s of metres in arid to semiarid climates. If surplus surface water can be diverted into open pits, rapid filling can accelerate groundwater recovery of open pits in regions of low permeability. This is a less successful management option in transmissive aquifers.

Evaluation of heavy metal contamination in copper mine tailing soils of Kitwe and Mufulira, Zambia, for reclamation prospects

Understanding the level of heavy metal contamination coupled with the assessment of environmental and human risks associated with mine waste dumpsites is an important step to initiating efficient measures for mine wasteland restoration, stabilization, and bioremediation. In the present study, concentration of the heavy metals; Copper (Cu), Cobalt (Co), Iron (Fe), Lead (Pb), Manganese (Mn), and Zinc (Zn) in soil from mine waste dumpsites around Kitwe (Sites: BM and TD26) and Mufulira (Site: TD10), Zambia, was assessed to determine the level of contamination, ecological risks, and progress made in reclamation. The mine waste dumpsites in the two towns are located in the vicinity of residential areas. Therefore, there is need to provide information for optimization of protocols for post-mining landscape in Zambia and elsewhere to limit soil, river, and groundwater contamination and to accelerate the restoration process . Mean values for soil pH, electrical conductivity, and organic matter varied between 5.9–8.4, 2534.8–538.6 μS/cm, and 0.90–2.75%, respectively. The mean concentrations of heavy metals of BM, TD26, and TD10 decreased in order of Fe > Cu > Co > Mn > Pb > Zn across all sites. However, the order of overall degree of heavy metal contamination computed using control soil as a baseline in BM, TD26, and TD10 was Cu > Co > Fe > Pb > Mn > Zn. The pollution load index was 0.355 at BM, 0.329 at TD26, and 0.189 at TD10, indicating high soil pollution at BM and TD26. The Potential Ecological Risk Index for all heavy metals tested at BM, TD26, and TD10 showed low ecological risk in the vicinity of the studied dumpsites. Furthermore, the present study also showed that the polluted soils around smelter sites and mine waste dumpsites are susceptible to dispersion by wind and water. Additionally, results from TD10 revealed that the initiated remediation of the tailings dam was somewhat successful. Finally, this study provided an updated status regarding the accumulation of heavy metals in mine waste dumpsites of Kitwe and Mufulira, Zambia and baseline information necessary to enhance post-mining landscape reclamation.

Exceptional Quantity of Water Habitats on Unreclaimed Spoil Banks

Surface mining is responsible for the large-scale destruction of affected landscapes. Simultaneously, the dumping of overburden soil on spoil banks during mining generates new landscapes, usually with heterogeneous topography. If spoil banks are not subsequently reclaimed technically (i.e., if the terrain is not leveled), considerable habitat diversity can thereby be established, consisting of numerous types of both terrestrial and water habitats. We compared the area and number of freshwater habitats between spoil banks (both technically unreclaimed and reclaimed) and the surrounding landscapes undisturbed by mining. The area of water habitats and especially their numbers per km2 were by far the greatest on unreclaimed spoil banks. Meanwhile, the quantity of water bodies on reclaimed spoil banks was about half that on non-mining landscapes. Great variety among the numerous water habitats, as indicated by their areas, depths, and proportions of aquatic vegetation on unreclaimed spoil banks, can contribute to regional landscape heterogeneity and water environment stability while providing conditions suitable for diverse taxa. The exceptional number of these water bodies can compensate for their loss in the surrounding landscape. We conclude that leaving some parts of spoil banks to spontaneous succession plays an irreplaceable role in the restoration of post-mining landscapes.

Applying Ecological Succession Theory to Birds in Solar Parks: An Approach to Address Protection and Planning

Renewable energy production will require large areas of land; production sites should be designed to include biodiversity conservation. Guidance for decision-makers on reasonable coexistence is needed. We use time-series data alongside a meta-study on birds in solar parks, utilizing succession theory to indicate which bird groups can thrive in solar parks. Using an evidence-based and interdisciplinary approach, we documented biodiversity and conditions at a 6 ha site in the newly created post-mining landscape of Lusatia, Germany, for 16 years, grouping avian species depending on the ecosystem state in which they were observed. In a key mid-period of early succession lasting eight years, the avifauna was characterized by successional groups 2, herbaceous plant-preferring, ground-breeding species; and 3, open shrub-preferring species. The preceding and following groups were: (1) pioneer bird species that prefer open ground; and (4), pre-forest species. Comparison of these data with available bird monitoring in solar parks showed that bird species of groups 2 and 3 can also successfully settle in open-space solar parks that have some natural habitat attributes, whereas this is hardly possible for the preceding and following groups. Using this information, opportunities for habitat improvement are facilitated, and potential conflicts can be addressed more purposefully.

Revegetation as a driver of chemical and physical soil property changes in a post-mining landscape of East Kalimantan: A chronosequence study

As a result of mixing soil materials from various natural soil horizons, mine soils generally have low organic C and total N content. In wet tropical climates where the vegetation is evergreen, we hypothesize that with the start of revegetation, the organic C and total N levels of the mine soils will recover rapidly and increase as the time since revegetation increases. The increase in organic C and total N content will have implications for changes in other soil chemical and physical properties. The development of mine soils in wet tropical climate conditions is so far rarely considered only. This study aims to determine changes in the physical and chemical properties of mine soils in the initial stages of formation triggered by the increasing time since revegetation. Soils from permanent observation plots in ex-coal mined sites divided by time since revegetation (0–12 years) were sampled together with an adjacent site with natural forest. Decisive soil physical and chemical properties were determined for the soils from 0 to 30 cm depth. With the increasing time since revegetation, there was a decrease in bulk density, and an increase in total soil porosity following a logarithmic equation. Linear changes with increasing time since revegetation were found for organic C, total N, and available P levels. The linear increase in organic C, total N, and available P levels, the logarithmic decrease in bulk density and the increase in total porosity with increasing time since revegetation suggest that these parameters are controlled by vegetation in the initial stages of mine soil development, while the polynomial changes in extractable P and K (25% HCl), CEC, exchangeable bases, base saturation percentage, and exchangeable Al over time suggest that these parameters can be assigned to processes independent of vegetation and are highly dependent on the composition of the original substrate.

An encounter with stone. Designing with the aesthetic force of post-mining landscapes.

Quarries are inherently complex situations that offer a unique and timely challenge to contemporary landscape architects. Their technical and operational nature tends to lead to an equally technical response by designers at the expense of engaging with the ethico-aesthetic potential of these confronting landscapes. Several designers and thinkers are responding to this problem through theorizing a revival of aesthetics that focuses on determining why certain landscape encounters occur, in order to use this as the basis from which to design. While attention has been given to theorizing the role of aesthetics in a contemporary design setting, less so has been directed to the practices and techniques suited to designing with these forces or doings. This paper uses the Horokiwi Quarry in New Zealand as an example to explore how the aesthetic forces can be understood as emerging from concrete spatiotemporal relations between the body and landscape. In doing so, it argues that greater attention needs to be paid to the specific, not generic, causes of aesthetic encounters so that stronger, more sustainable relations with nonhuman entities can be developed.

Lignite, Structural Change, Post-mining Landscapes - An Overview for Germany and Neighbours

Lignite, Structural Change, Post-mining Landscapes - An Overview for Germany and Neighbours

TRIM4Post-Mining: Transition Information Modelling for Attractive Post-Mining Landscapes—A Conceptual Framework

TRIM4Post-Mining is a H2020/RFCS-funded project that brings together a consortium of European experts from industry and academia to develop an integrated information modelling system. This is designed to support decision making and planning during the transition from coal exploitation to a revitalized post-mining landscape, enabling infrastructure development for agricultural and industrial utilization, and contributing to the recovery of energy and materials from coal mining dumps. The smart system will be founded upon a high-resolution spatiotemporal database, utilizing state-of-the-art multi-scale and multi-sensor monitoring technologies that characterize dynamic processes in coal waste dumps related to timely, dependent deformation and geochemical processes. It will integrate efficient methods for operational and post-mining monitoring, comprehensive spatiotemporal data analytics, feature extraction, and predictive modelling; this will allow for the identification of potential contamination areas and the forecasting of geotechnical risks and ground conditions. For the interactive exploration of alternative land-use planning scenarios—in terms of residual risks, technical feasibility, environmental and social impact, and affordability—up-to-date data and models will be embedded in an interactive planning system based on Virtual Reality and Augmented Reality technology, forming a TRIM—a Transition Information Modelling System. This contribution presents the conceptual approach and main constituents, and describes the state-of-the-art and detailed anticipated methodological approach for each of the constituents. This is supported by the presentation of the first results and a discussion of future work. An anticipated second contribution will focus on the main findings, technology readiness and a discussion of future work.

Creating an evidence base for managing structural change in the Rhineland Mining Area—evaluating open space applying a comprehensive set of indicators

Post-mining landscapes undergo thorough structural changes. Hereby, striking transitions take place concerning open spaces in particular. For the Rhineland Mining Area, the project DAZWISCHEN, with five thematic fields of action, in its first phase intends to capture the status quo of the region. Spatial talents and spatial barriers are identified as a result. Considering open space, we present a multi-method approach integrating basic land use data, ecosystem services, and combined indices. We disclose a bipartition of the region with two relatively homogenous areas regarding the assessment of the landscape or open spaces and their functionality. However, we also detect highly functional patches in ‘weaker’ surroundings, making their preservation and protection particularly important. Our results hail from a wide array of analyses using the available data as effectively as possible. Thus, we can provide information for politicians, practitioners, and scientists doing research in similar settings.

Treating acid mine drainage with decomposed organic soil: Implications for peatland rewetting

Acidification and salinisation of groundwater and surface water bodies are worldwide problems in post-mining landscapes due to acid mine drainage (AMD). In this study, we hypothesised that highly decomposed peat offers a suitable substrate for mitigating AMD pollution of water bodies and that hydraulic load affects the removal efficiency of iron and sulphate. A lysimeter experiment was conducted mimicking peatland rewetting to quantify iron and sulphate removal and pH changes at different loading rates. The low initial pH of 4 rose to 6 and electrical conductivity declined by up to 47%. The initially high concentrations of iron (>250 mg/L) and sulphate (>770 mg/L) declined by, on average, 87 and 78%, respectively. The removal efficiency of sulphate was negatively correlated with either the hydraulic or the sulphate load, respectively, i. e. the lower the hydraulic load, the higher the removal efficiency of sulphate. However, the removal of iron was not explained by the load. The results imply that desulphurication and thus subsequent precipitation of iron sulphides was the main removal process and that peatland rewetting is an effective measure to mitigate AMD pollution of freshwater systems. For the heavily AMD-polluted studied section of the River Spree, we estimated by combining experimental with field data that a sulphate load reduction of the river by about 20% (36,827 tons/yr) will occur if all peatlands in the sub-catchment (6067 ha; 6.7% of the total area) are rewetted. Future investigations must show if the pollutant removal is declining over time in decomposed peat layers due to acidification and/or lack of bioavailable carbon and how the rewetting of peatland with AMD will affect the restoration of their ecosystem functioning in the long term.

Multi-Criteria Decision Analysis for Evaluating Transitional and Post-Mining Options—An Innovative Perspective from the EIT ReviRIS Project

In mine design and planning, identifying appropriate Post-Mining Land Use (PMLU) is necessary and crucial to achieving environmental quality and socioeconomic renewal. In this context, Multi-Criteria Decision Making (MCDM) methods are used to support decision-maker and stakeholder decisions. However, most studies regarding the application of MCDM methods to PMLU decisions do not favor their widespread use because they start from an already structured decisional problem. The structure they present may not apply to another PMLU decision. Therefore, the primary goal of this study is to present an innovative methodology and its corresponding framework to help decision-makers and stakeholders structure their PMLU decisions. This innovative methodology can be used from an early stage, with a low level of detail, until a later stage, with a high level of detail, and is composed of three main stages. The first stage is selecting the Transitional Post-Mining Landscape Profile, which guides the user to different Multi-Criteria Decision Analysis (MCDA) goals. The second stage is developing criteria and alternatives according to the MCDA goal, using topics representing essential dimensions that cannot be disregarded, and testing the MCDM methods. Finally, the third stage is the participatory process and final application of MCDM methods.

Mobilising subterranean geopolitics: The spectre of spontaneous combustion and post mining imaginaries

In the context of a groundswell of interest in developing innovative post-mining landscapes, this paper explores post-mining imaginaries through the example of a recently closed coal mine, Leigh Creek in South Australia. We explore how these imaginaries are put forward by the mine’s local communities, multiple levels of government and the mining company itself. In this case, as occurs more broadly in coal mining, these imaginaries are co-constructed by the ever-present risk of underground spontaneous combustion—spon-com—as a result of mining practices. This article addresses the role of spon-com as not only a physical phenomenon of the underground, but as a socio-environmental mechanism wielding considerable political power in relation to post-mining possibilities. We contribute to the geopolitical discourse on the ‘subterranean turn’ by drawing on concepts of haunting-as-circumstance to explore the political agency of the underground to reach above and manipulate surface politics. We thereby complicate Maria de Lourdes Melo Zurita’s identification of a pre-existing sub terra nullius that positions the subsurface as political nothingness awaiting human intervention. This is a crucial step forward in thinking through concepts informing understandings of surface–subsurface relations, including the introduction of spectral thinking within subterranean geopolitics. We thus advance scholarship on subterranean geographies by progressing concepts of inhuman agency grounded in a situated example of this agency in practice.

The centenary jubilee of the discovery of prehistoric striped flint mines in Krzemionki

Undoubtedly, the exploitation field in Krzemionki, situated within the properties of the present villages of Sudół, Stoki Stare and Ruda Kościelna, constitutes a unique relic – the monument of prehistory whose preservation in as good state as possible accompanied with skilful facilitating it to the public is going to be the subject of our concern throughout the upcoming century. From one hand, one could be surprised that the monument did not become a symbol equally recognizable to the Biskupin fortified town. On the other, it should be admitted with delight that the whole range of activities completed regarding the monument have not caused any significant alterations to the object as specified. They might possibly occur along with vaster popularization and commercialization of Krzemionki mines. Of course, some interference took place here indeed. However, luckily their scale have not caused loss which we could reckon as considerable, taking into account the number of intact mining shafts or post-mining landscape, visible until today at substantial stretch of the field. It seems that in the case of this archaeological monument a successful compromise was obtained. It merges a strive for retaining as little changed state as possible, getting knowledge in the course of research and finally the need for the knowledge and the object as it is to be presented. If we manage to keep the situation like that it will be possible to claim that intergenerational actions of various environments in the service of Krzemionki monument led to proper effects.

Effects of less impermeable sealings for mine piles

Saline contaminants from potash mining endanger aquatic ecosystems. Uncovered piles of potash tailings release high amounts of chloride and sodium. Conventional coverage systems with a transpiration-intensive vegetation on a soil layer reduce percolation water only to some extent and do not protect the surrounding environment sufficiently. Powerful sealings are used to cover other mining deposits but are still uncommon for potash tailings piles. Because clay for constructing a sealing is limited, an alternative coverage system is required. The aim of this study is to identify a coverage system that conserves resources but also effectively minimises the release of contaminants. Water balance components (evapotranspiration, runoff, storage) of 44 different coverage systems were modelled with BOWAHALD. 4 model settings describe common conventional coverage and 40 settings include an additional sealing. The chosen coverage systems differ in soil layer thickness (1.5 to 3 m), vegetation productivity as well as in the thickness (10 and 50 cm) and impermeability of the sealing (kf values range between 8 × 10−08 and 5 × 10−09 m/s). The most impermeable sealing is also common whereas the less impermeable sealings are new designed. The results show that an additional sealing always outperforms (max. 26% percolation rate) conventional coverage without an additional sealing (28.7% percolation rate). Furthermore, a coverage system with less impermeable sealing and lush vegetation can substitute a coverage system with a more impermeable sealing and sparse vegetation without changing the percolation rate. Site-specific examinations, considering geographical orientation and inclination, show that a more impermeable sealing works best on north-facing slopes, whereas lush vegetation performs better on south-facing slopes. A mixed coverage according to site-specific performance reduces the percolation rate more than uniform coverage and requires less sealing material. I conclude that a mixed and site-specific coverage system is the most effective one to improve water quality in post-mining landscapes.

The hydrochemical evolution of a constructed peatland in a post-mining landscape six years after construction

Study RegionReclamation of wetlands, including peatlands, is legally required in the Athabasca oil sands region following bitumen extraction via surface mining which leaves large open pits that are backfilled with saline tailings waste. Study FocusSix years of hydrochemical data (2013 – 2018) from the Sandhill Fen Watershed (SFW), a 52-ha upland-peatland catchment that was built upon highly saline soft tailings, were used to evaluate salinity and ion patterns and provide insight on its trajectory. In general, electrical conductivity (EC) increased throughout SFW from 1) reduced inflow and outflow, 2) changes in water table positions and 3) increased mixing of site-wide waters. New Hydrological Insights for the RegionSalinity has increased site-wide over time as EC increased by an average of 1585 and 2313 µS/cm in the wetland and margins, respectively from 2013 to 2018. The uplands were the only region where EC declined by 1747 µS/cm over the six years. There is also evidence of mixing with underlying tailings waste (Na-Cl dominant) as the chemical composition of SFW waters shifted from largely Ca-dominant in 2013 (> 90%) to Na-dominant by 2018 (> 70%). Based on its current conditions, SFW cannot support freshwater peat-forming bryophytes and is most chemically similar to naturally occurring saline fens. A shift in design strategies is recommended (replicating saline instead of freshwater peatlands) to increase the success of these systems.