Steering restoration of coal mining degraded ecosystem to achieve sustainable development goal-13 (climate action): United Nations decade of ecosystem restoration (2021-2030)

A combined bibliometric and sustainable approach of phytostabilization towards eco-restoration of coal mine overburden dumps

Extraction of coal through opencast mining leads to the buildup of heaps of overburden (OB) material, which poses a significant risk to production safety and environmental stability. A systematic bibliometric analysis to identify research trends and gaps, and evaluate the impact of studies and authors in the field related to coal OB phytostabilization was conducted. Key issues associated with coal extraction include land degradation, surface and groundwater contamination, slope instability, erosion and biodiversity loss. Handling coal OB material intensifies such issues, initiating additional environmental and physical challenges. The conventional approach such as topsoiling for OB restoration fails to restore essential soil properties crucial for sustainable vegetation cover. Phytostabilization approach involves establishing a self-sustaining plant cover over OB dump surfaces emerges as a viable strategy for OB restoration. This method enhanced by the supplement of organic amendments boosts the restoration of OB dumps by improving rhizosphere properties conducive to plant growth and contaminant uptake. Criteria essential for plant selection in phytostabilization are critically evaluated. Native plant species adapted to local climatic and ecological conditions are identified as key agents in stabilizing contaminants, reducing soil erosion, and enhancing ecosystem functions. Applicable case studies of successful phytostabilization of coal mines using native plants, offering practical recommendations for species selection in coal mine reclamation projects are provided. This review contributes to sustainable approaches for mitigating the environmental consequences of coal mining and facilitates the ecological recovery of degraded landscapes.

The impact of climate change and production technology heterogeneity on China's agricultural total factor productivity and production efficiency

Sustainable agricultural production efficiency is important for global food security, environmental conservation, economic development, human Health, and social equity. However, Climate change has had a significant impact on global agricultural productivity. To this end, investigating climate change's effect on agricultural production efficiency is critical for the food security of any particular country or region, and China is not distinct. Further, the influencing factor of agricultural total factor productivity (technology or technical efficiency) and regional heterogeneity in agricultural production technologies of China are worth exploring for sustainable agricultural growth. To this end, this study employed the DEA-Malmquist Productivity Index to gauge the total factor productivity change (TFPC) in 31 provinces and administrative units of China from 2000 to 2021. Additional inputs of climate factors were added to the estimation process to explore the impact of climate change on TFPC for different periods and regions. The meta-frontier analysis estimates the agriculture production technology gap among nine regions of China. Results revealed that climate factors could overestimate China's average total factor agricultural productivity over the study period. Among 8 out of 9 regions in China witnessed the diverse effects of climate factors; however, it positively impacted agricultural TFPC in the Qinghai Tibet Plateau. Sichuan Basin and surrounding regions performed best, ranked top in China with an average growth rate of 22.3 % in TFPC. Decomposing the TFPC into efficiency and technological change, the study found that the influence of climate on technological change is greater than compared to efficiency change. Northeast China Plain and Sichuan Basin and surrounding regions have superior agriculture production technology with a TGR score 1. Mann-Whitney U and Kruskal-Wallis test proved the statistically significant difference among agricultural productivity scores estimated with and without climate factors and production technology gaps among nine regions of China.

Physiochemical analyses and molecular characterization of heavy metal-resistant bacteria from Ilesha gold mining sites in Nigeria

BACKGROUND

The contribution of the processes involved and waste generated during gold mining to the increment of heavy metals concentration in the environment has been well established. While certain heavy metals are required for the normal functioning of an organism, certain heavy metals have been identified for their deleterious effects on the ecosystem and non-physiological roles in organisms. Hence, efforts aimed at reducing their concentration level are crucial. To this end, soil and water samples were collected from Ilesha gold mining, Osun State, Nigeria, and they were subjected to various analyses aimed at evaluating their various physicochemical parameters, heavy metal concentration, heavy metal-resistant bacteria isolation, and other analyses which culminated in the molecular characterization of heavy metal-resistant bacteria.

RESULTS

Notably, the results obtained from this study revealed that the concentration of heavy metal in the water samples around the mining site was in the order Co > Zn > Cd > Pb > Hg while that of the soil samples was in the order Co > Cd > Pb > Hg > Zn. A minimum inhibitory concentration test performed on the bacteria isolates from the samples revealed some of the isolates could resist as high as 800 ppm of Co, Cd, and Zn, 400 ppm, and 100 ppm of Pb and Hg respectively. Molecular characterization of the isolates revealed them as Priestia aryabhattai and Enterobacter cloacae.

CONCLUSION

Further analysis revealed the presence of heavy metal-resistant genes (HMRGs) including merA, cnrA, and pocC in the isolated Enterobacter cloacae. Ultimately, the bacteria identified in this study are good candidates for bioremediation and merit further investigation in efforts to bioremediate heavy metals in gold mining sites.

Tree-level landscape transitions and changes in carbon storage throughout the mine life cycle

Opencast mining activities destroy native vegetation, directly impacting the carbon sequestration capacity of the regional ecosystem. Restoring tree species have significant impacts on carbon storage. However, changes in carbon storage across tree-level landscape and the impact of tree-level landscape transitions on carbon storage remain poorly described in the literature, and this information is urgently needed to support management decisions. In this study, we combined field data and remote sensing techniques to create field data-driven maps of the tree-level landscape. This enabled the assessment of carbon storage and quantification of the impact of tree-level landscape transitions on carbon storage. We founded that carbon storage rises in initial/stable stages, decreases in development stage during mining expansion and reclamation. The choice of restoration tree species significantly influenced carbon storage. Pinus tabuliformis-R. pseudoacacia accumulated more carbon storage, making it a more suitable model for ecological reclamation of Pingshuo opencast mine. Furthermore, changes in carbon storage are influenced by land-use policies. Land-use policies and reclamation efforts counterbalance carbon loss associated with construction. Various tree-level landscape transitions were examined, with Pinus tabuliformis transitions notably affecting carbon storage, offering insights for ecological reclamation planning. Our research provides a reference for carbon storage assessment in opencast mining areas, enhances understanding of carbon storage changes in mining areas, assists in formulating ecological reclamation plans, and contributes to the "dual‑carbon" goals and climate change mitigation.

Native Plant Species: a Tool for Restoration of Mined Lands

The COVID-19 epidemic, food and water insecurity, and the climate emergency have impacted the lives of billions of people worldwide. Ecosystems play a crucial role in tackling these problems. Hence, it is a prime necessity to keep the ecosystems safe and sustainably manage the resources. But this would not suffice for the protection and sustainable management of our surviving natural landscapes and oceans; we also need to restore the planet's devastated ecosystems and the enormous benefits they give. Mining exerts a lot of pressure on the land resources further depleting the fertility of the soil. The overburdened dumps are devoid of the nutrients which turns natural succession at a slow pace. The restoration of the degraded mined areas is essential to re-establish the ecological balance so that a self-sustaining ecosystem can be maintained. The plantation of selected species of plants could be a sustainable and organic tool for the restoration of the degraded mined land. In today's context, various ways regarding ecological restoration are suggested, but the native plant species plantation is the best tool for restoring the degraded land at a quicker pace. The present paper reviews the importance of the native plant species and their efficacy in restoring degraded mined land based on area and time of succession and climax.