Plant-Soil Feedbacks for the Restoration of Degraded Mine Lands: A Review

Much effort has been made to remediate the degraded mine lands that bring severe impacts to the natural environments. However, it remains unclear what drives the recovery of biodiversity and ecosystem functions, making the restoration of these fragile ecosystems a big challenge. The interactions among plant species, soil communities, and abiotic conditions, i.e., plant-soil feedbacks (PSFs), significantly influence vegetation development, plant community structure, and ultimately regulate the recovery of ecosystem multi-functionality. Here, we present a conceptual framework concerning PSFs patterns and potential mechanisms in degraded mine lands. Different from healthy ecosystems, mine lands are generally featured with harsh physical and chemical properties, which may have different PSFs and should be considered during the restoration. Usually, pioneer plants colonized in the mine lands can adapt to the stressful environment by forming tolerant functional traits and gathering specific soil microbial communities. Understanding the mechanisms of PSFs would enhance our ability to predict and alter both the composition of above- and below-ground communities, and improve the recovery of ecosystem functions in degraded mine lands. Finally, we put forward some challenges of the current PSFs study and discuss avenues for further research in the ecological restoration of degraded mine lands.

Proposals for an environmental and social just transition for the post-lignite era in Western Macedonia, Greece

This text formulates a set of coherent and realistic proposals for the after delignification period in Western Macedonia. The aim of these proposals is to avoid the economic decline and poverty of the Region. The first part, based on the literature and the best available practices, the proposals for the necessary environmental restoration of mine lands. Concerning the economic rehabilitation of the Region, a mix of actions referring to the whole production chain: from the primary to the tertiary sector of the economy, is proposed. The action that is expected to enhance the production potential of this region is the creation of branded products, under a single brand name, which will voluntarily bring together, in the context of synergies, the agri-food and manufacturing activities. Overall, it is estimated that the deadline set for de-lignification in 2023, is too early to start all those activities that will allow the economic transition of the Region, and to exclude the possibility of a massive wave of migration. For this reason, the extension of de-lignification, for a period of time within the European objectives to achieve the target of climate neutrality in 2050, are proposed.

Reclamation of Abandoned Mine Soil: A Review on Properties and Remediation Techniques

The environment which is a part of ecosystem is being polluted due to urbanization, rapid industrialization increased demands for resources in our day to day lives have left no resources untouched. Various anthropogenic activities such as mining and milling operations, which include grinding, screening, concentrating ores and removal of tailings, disposal of mine and mill waste water release toxic metals into the natural environment affecting the lithosphere. Reclamation is the process of restoring the environmental soundness of these distressed mine lands. It consists of governing all kinds of physical, chemical and biological inconvenience of land area or soil such as fertility, pH, microbial activities and different soil nutrient cycles that make the destructed land soil fertile. The main aim of the reclamation is to bring back the fertility of soil by increasing its N, P, K values and Carbon contents. There are various remediation technologies available for removal of heavy metal from contaminated mine soil, in this paper we have discussed in-situ remediation, physical remediation, chemical remediation and biological remediation technologies which are implemented across the globe.

Abandoned Mine Lands Reclamation by Plant Remediation Technologies

Abandoned mine lands (AMLs), which are considered some of the most dangerous anthropogenic activities in the world, are a source of hazards relating to potentially toxic elements (PTEs). Traditional reclamation techniques, which are expensive, time-consuming and not well accepted by the general public, cannot be used on a large scale. However, plant-based techniques have gained acceptance as an environmentally friendly alternative over the last 20 years. Plants can be used in AMLs for PTE phytoextraction, phytostabilization, and phytovolatilization. We reviewed these phytoremediation techniques, paying particular attention to the selection of appropriate plants in each case. In order to assess the suitability of plants for phytoremediation purposes, the accumulation capacity and tolerance mechanisms of PTEs was described. We also compiled a collection of interesting actual examples of AML phytoremediation. On-site studies have shown positive results in terms of soil quality improvement, reduced PTE bioavailability, and increased biodiversity. However, phytoremediation strategies need to better characterize potential plant candidates in order to improve PTE extraction and to reduce the negative impact on AMLs.

Soil Water Movement of Mining Waste Rock and the Effect on Plant Growth in Arid, Cold Regions of Xinjiang, China

Understanding the water movement in reconstructed soil and its efficacy on local vegetation is critical for the ecological reclamation of mine lands. This study employed field experiments and a numerical model to investigate the water movement in reconstructed soil and evaluate the effects of mining waste rock on plant growth in an arid and cold region of Xinjiang. Water contents and matrix potentials were monitored over 1-year period. A numerical model was established based on the observed data to calculate soil water balance and irrigation demand. The results show that the soil water content at a shallow depth could be more vulnerable to the climate variability in uncompacted and compacted soil. The water content at the depth of 50 cm with 30 cm-thick covering soil was the lowest; meanwhile, the barrels with 50 cm- and 70 cm-thick covering soil without compaction had the highest water content. Moreover, the water content of the uncompacted soil could be lower than that of the counterpart attributed to the variation in soil porosity. To maintain the water content as an optimized value to grow a certain plant species in the long run, irrigation could be implemented according to the water balance over time in mine lands.

Assessment and abatement of the eco-risk caused by mine spoils in the dry subtropical climate

The highly rugged mountainous land topography of the Novorossiysk industrial agglomeration (NW Caucasus, Krasnodar Krai, Russia) and arid climate limit the restoration abilities of disturbed mine lands. Abandoned waste-rock dumps of a marl quarry occupy an area of ca. 150,000 m2 next to the cement plant, residential districts, and a commercial seaport. To assess the eco-risk, topsoil horizons of urban and mine-site Technosols and background Rendzinas were sampled and analyzed; measurements of particulate matter fractions PM1, PM2.5, PM4, and PM10 were conducted throughout the agglomeration. Fugitive dust emission from the unreclaimed marl dumps raises the PM2.5 content in the air by a factor of 2.68 on average. The high sorption capacity of the fine eluvium results in the accumulation of urban emissions by the dust and contributes to the subsequent soil pollution; the Cumulative Pollution Index of pedochemical anomalies reaches the high-risk level over the areas of up to 5 km2. Environmental threats caused by the mine dumps can be assessed more reliably by means of land zoning based on accumulated environmental damage indicators and the debris flow and waterspout risk calculation. To abate the technogenic impact caused by the mine spoils, reclamation actions must be taken including soil stabilization on sensitive sites by application of geosynthetic cover, hydroseeding of the mixture of soil improvers and seeds of herbaceous plants on the slopes, and anti-erosion plantation of cades (Juniperus oxycedrus L.) and smoke trees (Cotinus coggygria Scop.) at subhorizontal surfaces.

Mapping Potentially Acid Generating Material on Abandoned Mine Lands Using Remotely Piloted Aerial Systems

Weathering and transport of potentially acid generating material (PAGM) at abandoned mines can degrade downstream environments and contaminate water resources. Monitoring the thousands of abandoned mine lands (AMLs) for exposed PAGM using field surveys is time intensive. Here, we explore the use of Remotely Piloted Aerial Systems (RPASs) as a complementary remote sensing platform to map the spatial and temporal changes of PAGM across a mine waste rock pile on an AML. We focus on testing the ability of established supervised and unsupervised classification algorithms to map PAGM on imagery with very high spatial resolution, but low spectral sampling. At the Perry Canyon, NV, USA AML, we carried out six flights over a 29-month period, using a RPAS equipped with a 5-band multispectral sensor measuring in the visible to near infrared (400–1000 nm). We built six different 3 cm resolution orthorectified reflectance maps, and our tests using supervised and unsupervised classifications revealed benefits to each approach. Supervised classification schemes allowed accurate mapping of classes that lacked published spectral libraries, such as acid mine drainage (AMD) and efflorescent mineral salts (EMS). The unsupervised method produced similar maps of PAGM, as compared to supervised schemes, but with little user input. Our classified multi-temporal maps, validated with multiple field and lab-based methods, revealed persistent and slowly growing ‘hotspots’ of jarosite on the mine waste rock pile, whereas EMS exhibit more rapid fluctuations in extent. The mapping methods we detail for a RPAS carrying a broadband multispectral sensor can be applied extensively to AMLs. Our methods show promise to increase the spatial and temporal coverage of accurate maps critical for environmental monitoring and reclamation efforts over AMLs.

Optimizing the micropropagation protocol for Rosa canina L. elite genotype propagation in the Belgrade area

Rosa canina L. (dog rose) is an important ornamental, edible and medicinal plant. It has been used as a rootstock for ornamental roses, grown in plantations for fruit harvesting and it is suitable for revegetation of abandoned mine lands. The propagation of native genotypes that are well adapted to local conditions can provide planting material for both revegetation and plantation purpose. Micropropagation is the most suitable method for a rapid vegatative propagation of selected wild genotypes, but an increased presence of pathogens as well as higher contamination rate during culture establishment were expected. An occurrence of a specific Fe-chlorosis during in vitro propagation of roses is also possible. Therefore, the optimal period and disinfection protocol for establishing sterile in vitro culture of selected genotypes of dog rose was investigated, as well as an effect of increasing the FeEDTA concentration in the MS medium during multiplication phase. The obtained results showed that the optimal time for taking initial explants corresponds to optimal time for taking green cuttings in traditional vegetative propagation by softwood cuttings, and the best results were achieved using shoots collected in the first week of May, when the flowers were open. The iron chelate concentration in the medium affected the mean number of shoots, and doubling of its concentration resulted in a considerably higher number of shoots per explant.

From the Ground Up: Prairies on Reclaimed Mine Land—Impacts on Soil and Vegetation

After strip mining, soils typically suffer from compaction, low nutrient availability, loss of soil organic carbon, and a compromised soil microbial community. Prairie restorations can improve ecosystem services on former agricultural lands, but prairie restorations on mine lands are relatively under-studied. This study investigated the impact of prairie restoration on mine lands, focusing on the plant community and soil properties. In southeast Ohio, 305 ha within a ~2000 ha area of former mine land was converted to native prairie through herbicide and planting between 1999–2016. Soil and vegetation sampling occurred from 2016–2018. Plant community composition shifted with prairie age, with highest native cover in the oldest prairie areas. Prairie plants were more abundant in older prairies. The oldest prairies had significantly more soil fungal biomass and higher soil microbial biomass. However, many soil properties (e.g., soil nutrients, β-glucosoidase activity, and soil organic carbon), as well as plant species diversity and richness trended higher in prairies, but were not significantly different from baseline cool-season grasslands. Overall, restoration with prairie plant communities slowly shifted soil properties, but mining disturbance was still the most significant driver in controlling soil properties. Prairie restoration on reclaimed mine land was effective in establishing a native plant community, with the associated ecosystem benefits.