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The properties and sources of soil heavy metals (Pb, Zn, Cu, Cd, As, Hg, Cr, and Ni) need to be comprehensively analyzed to take effective steps to control and reduce soil pollutants. In this research, 416 soil samples were collected on a large scale in China. Two receptor models (PCA/MLR and PMF) were utilized to identify pollutant sources and quantify the contributions. The means of soil heavy metals (Zn, Cu, As, Hg, Cr, and Ni) were lower than the corresponding screening values and intervention values. Cd was greater than the intervention value, while Pb was between the screening value and the intervention value. Source apportionments suggested that mine sources were the most polluted (64.28%), followed by traffic sources (38.98%), natural sources (11.41-39.58%), industrial sources (9.8-18.65%), and agricultural sources (2.79-14.51%). Compared to the PCA/MLR model, the PMF model had a better effect in evaluating soil heavy metal pollution. It gave corresponding weights according to the data concentration and its uncertainty, which made the result reasonable. The ecological risk assessment indicated that Cd posed a significant risk, while Hg caused a mild risk and the other six heavy metals posed a low risk. The spatial distribution of ecological risk suggested that severe risk points were mainly distributed in the central area, while high-risk points were distributed in the southern region. The SRI method was developed to link pollution sources and their potential ecological risks and indicated better applicability to the PMF model. The study findings could provide guidelines for monitoring the main sources and reducing the pollution of soil heavy metals.

Carbon neutrality lays out a grand blueprint for carbon emission reduction and climate governance in China. How to reduce energy consumption is the key to achieving this goal. The economic development and energy consumption show a very large gap at the provincial level, and this paper divides China into six regions (North, Northeast, East, Mid-South, Southwest, and Northwest) and analyzes the dynamic changes and reveals the driving factors that have affected CO2 emission changes from 1997 to 2017. Then, the driving forces including energy intensity, energy structure, energy efficiency, economic activity, and population scale were discussed employing the logarithmic mean Divisia index (LMDI) based on provincial panel data. The results show that CO2 emissions from energy consumption show an upward trend, from 4145 Mt in 1997 to 13,250 Mt in 2017, with an annual average growth rate of 1.06%; coal consumption is the main source of CO2 emission. The regions with the highest proportion of CO2 emissions are the East and North, which account for 50% of total emissions. China’s CO2 emissions from energy consumption, coal consumption, and output have shown significant spatial autocorrelation at the provincial scale. According to coal consumption, energy consumption CO2 emissions are divided into three stages: phase I (1997–2002), the increase in CO2 emissions in six regions was attributed to significant and positive impacts of energy intensity, economic activity, and population scale, the effects of which exceeded those of the energy structure and energy efficiency; phase II (2003–2012), the economic activity effect on CO2 emissions was highest in the East region, followed by the North and Mid-South regions; phase III (2013–2017), the East, Mid-South, and Southwest regions of China were dominated by the positive effects of energy intensity, economic activity, and population scale. The major driver of CO2 emissions is economic activity; the energy efficiency effect is an important inhibitory factor. Regional economic development and energy consumption in China are unbalanced; we conclude that differentiated emission reduction measures should be of particular concern for policymakers.

Carbon neutrality lays out a grand blueprint for carbon emission reduction and climate governance in China. How to reduce energy consumption is the key to achieving this goal. The economic development and energy consumption show a very large gap at the provincial level, and this paper divides China into six regions (North, Northeast, East, Mid-South, Southwest, and Northwest) and analyzes the dynamic changes and reveals the driving factors that have affected CO2 emission changes from 1997 to 2017. Then, the driving forces including energy intensity, energy structure, energy efficiency, economic activity, and population scale were discussed employing the logarithmic mean Divisia index (LMDI) based on provincial panel data. The results show that CO2 emissions from energy consumption show an upward trend, from 4145 Mt in 1997 to 13,250 Mt in 2017, with an annual average growth rate of 1.06%; coal consumption is the main source of CO2 emission. The regions with the highest proportion of CO2 emissions are the East and North, which account for 50% of total emissions. China’s CO2 emissions from energy consumption, coal consumption, and output have shown significant spatial autocorrelation at the provincial scale. According to coal consumption, energy consumption CO2 emissions are divided into three stages: phase I (1997–2002), the increase in CO2 emissions in six regions was attributed to significant and positive impacts of energy intensity, economic activity, and population scale, the effects of which exceeded those of the energy structure and energy efficiency; phase II (2003–2012), the economic activity effect on CO2 emissions was highest in the East region, followed by the North and Mid-South regions; phase III (2013–2017), the East, Mid-South, and Southwest regions of China were dominated by the positive effects of energy intensity, economic activity, and population scale. The major driver of CO2 emissions is economic activity; the energy efficiency effect is an important inhibitory factor. Regional economic development and energy consumption in China are unbalanced; we conclude that differentiated emission reduction measures should be of particular concern for policymakers.

Underground coal mining leads to serious surface deformation, which negatively affects the physical properties of soils Soil particle size distribution (PSD) is one of the most basic soil physical characteristic that influences other important properties such as soil hydraulics and thermodynamics. Understanding the spatial variability of the soil PSD in subsided land can provide targeted guidance for land reclamation. In this study, we conducted a quantitative study on the spatial variability of the soil PSD in the Pingshuo mining area on the Loess plateau, Shanxi Province in China, and explored the effects of subsidence and reclamation on the soil PSD. A plot experiment, including one unmined plot (UMP), one subsided plot (SUP), and one reclaimed plot (RCP), was performed in Anjialing No.3 underground coal mine in the, Pingshuo mining area. Four multi-fractal parameters of the soil PSD—D(0), D(1), Δα(q), and Δf(α)—were analyzed at the three sample sites. The joint multi-fractal method was carried out to analyze the spatial correlation of the soil PSD to further reveal the impacts of coal mining subsidence and land reclamation on the soil PSD. The multi-fractal method can reflect the local non-uniformity and heterogeneity of the soil PSD, while the joint multi-fractal approach can illustrate the correlation of the soil PSD between different soil depths. The range and spatial variability of the soil PSD increased due to coal mining subsidence and the impact of subsidence on the spatial disturbance of the surface soil PSD was greater than that of the deeper layers. The spatial correlation of clay in subsided land was larger than those of unmined land and reclaimed land, whereas, for silt and sand, the correlation was smaller. Land reclamation decreased the spatial variability of the soil PSD, which was near that of the unmined land after reclamation.

The surface soil and vegetation had been destroyed by opencast mining, leading the decrease of the vegetation fractional coverage, which caused a severe damage to the mining area and ecosystems. However, land reclamation in mining area minimized the damage to the environment and was an important part of mine production and construction to improve the vegetation fractional coverage and restore the local ecological balance. To analyze the effects of anthropogenic activities on vegetation, the vegetation fractional coverage (VFC) and vegetation index (VI) of the whole Pingshuo opencast coal mine area from Shanxi province of China and four individual reclaimed dumps in this coal mine area were calculated respectively based on remote sensing images. The spatial distribution of vegetation fractional coverage was analyzed using Moran's Index. From 1992 to 2015, the vegetation fractional coverage of the whole coal mine area increased from 0.31 to 0.53, showing a benign development trend with significant change from 2000 to 2015, and it was the lowest in 2009. Moreover, The vegetation fractional coverage transformed from extremely low coverage, low coverage, to middle coverage, middle high coverage, and high coverage during 23 years, which was improved clearly. The long reclamation period is conducive to vegetation restoration, and the reclamation project has a direct effect and significance for the restoration of the ecological environment of the mining area. The vegetation fractional coverage of four dumps in the study area were the lowest at the initial reclamation time, and increased with increasing reclamation time. The vegetation coverage of the Southern dump, Western A dump, Inner dump and Western B dump increased from 0.29 to 0.68, 0.34 to 0.59, 0.5 to 0.76, and 0.46 to 0.54, respectively. The increase of the global Moran's Index from 0.80 to 0.91 indicated that the spatial agglomeration was greatly influenced by anthropogenic activities from 1992 to 2015. The local Moran's Index showed that the vegetation fractional coverage of the whole stage was mainly high-high clustering and low-low clustering in 2015, and the vegetation fractional coverage of the dumping sites changed from the original low-low clustering to high-high clustering from 1992 to 2015. The area was heavily affected by both mining and reclamation, the vegetation fractional coverage of the dump site was significantly improved after reclamation.

Soil properties in reclaimed land altered inevitably due to human activities. To realize sustainable land use and management in mining area, the long-term dynamic monitoring of reclaimed soil properties is required. Traditional dense sampling network is time consuming and expensive. Therefore, it is necessary to devise a scientific sampling design that maximizing the accuracy of results while minimizing the costs. In this study, we developed an improved simulated annealing method considering the spatial correlation to optimize the sampling design for soil properties, to enhance the efficiency of sampling plans for the prediction of space variables. A separate optimization for each soil property and a sampling optimization integrating various soil properties were conducted by combining simulated annealing and artificial neural networks. The number of sampling points from present improved simulated annealing method was markedly reduced, the spatial correlation was increased and the sampling points obtained showed more accurate predictions for soil properties. The sampling points for each soil property were mostly distributed in the marginal areas and appropriately added in the middle of the dumps. There were more sampling points distribution in these areas with large changes in topography for each soil property after improved simulated annealing optimization and more sampling points were needed to reflect soil information in southern dump in Antaibao opencast coal mine. When operating optimization integrating all the properties, some sampling points of various properties were added to the sampling pattern, showing a uniform distribution of sampling points. This study provides a theoretical basis for optimal design for soil property monitoring and sustainable land management.

China's Loess Plateau region has a weak ecological environment, and the government has invested a considerable amount of money to repair the ecological environment. Vegetation plays an important role in the ecological environment. The Sen slope analysis and the Mann-Kendall trend test were used to analyze the trend and significance of vegetation coverage from 2000 to 2015. The vegetation coverage was analyzed to investigate the influence of land use types and conversion. The Pearson Correlation Test and qualitative analysis were utilized at the pixel and regional scales to investigate the influence of meteorological factors and topographical factors. The fluctuation of vegetation in Shaanxi was analyzed from 2000 to 2015. The impact of anthropogenic activities was investigated using residual trend analysis. Hurst exponent and H/S analysis were applied to investigate the potential future vegetation coverage trend. The vegetation coverage in Shaanxi Province improved from 2000 to 2015. In unchanged land use types, all types showed significant improvements expect for other construction land. In changed land use types, most of the land use types converted into urban land showed degradation. All the land use types converted into dry land, forest, and unused land showed improvements. Ecological protection has achieved great results. Precipitation and temperature partly affect vegetation coverage in Shaanxi. Gradients and elevation affected the distribution of vegetation coverage and human activities influenced land use type and the ecological environment. In the future, potential degradation risks still exist in the parts of Shaanxi Province.

Large-scale opencast coal mining results in the severe destruction of original ecosystems, as well as changes in land use. The complex network approach can be helpful for understanding the complex land use process. In this study, the complex network approach was used to analyze the land use change in the Pingshuo opencast coal mine area in the Shanxi province of China. Using six periods of land use data from 1986 to 2015, a complex network of land use change of five stages was constructed. The values of node degree, betweenness, and average shortest path in the network were calculated to identify the key land use type, the transformation process of different land use types and to discuss the stability of land use systems. Moreover, the main parts of complex networks were selected to evaluate the temporal and spatial changes of land use processes. From 1986 to 2015, with the dual influence of coal mining and high-speed urbanization, the amount of agricultural land decreased; in contrast, the amount of construction land, industrial and mining area land generally increased. Agricultural land was the main output land type, and construction land and industrial and mining area land were the main input land types. Cultivated land, forest land, and grassland were the key land use types during land processes from 1986 to 2009. Cultivated land, forest land, stripping areas and dumping areas became the key land types from 2009 to 2013, and from 2013 to 2015, cultivated land, forest land, and transportation land became the key land types. Large-scale opencast mining activities severely affect land use change. The overall stability of the land-use system was poor, and the system had the worst stability because of the intensification of mining activities from 2009 to 2013. Local government and coal enterprise should carry out some measures to improve the land use in large-scale opencast coal mine areas, including laying emphasis on land-saving use during mining processes, protecting agricultural land, controlling construction land, strengthening land reclamation, optimizing the use of reclamation land, and using “lease instead of expropriation” to carry out the reform of mined land.

As two main factors, soil and vegetation play key roles in land rehabilitation and ecological remediation of mining areas. There is a complex interaction between soil and vegetation, and understanding the mechanisms of interaction between soil and vegetation is of great significance for land rehabilitation and ecological remediation in mining areas. This study introduced complex network method to analyze the complex interaction systematically. A survey of vegetation and soil properties in 70 reclaimed plots was carried out in the Anjialing and Antaibao opencast coal-mines in Shanxi, China. The indices of soil and vegetation acted as nodes, and the interaction between these indices as sides to establish a soil-vegetation network. Calculating the network indices to analyze the structure of a complex network and explore the mechanism of interaction between soil and vegetation. SOM (soil organic matter) was at the core of the soil-vegetation interaction network. The average path length of the soil-vegetation network was 1.8, with a faster rate of information transfer. The soil-vegetation network consisted of three clusters (soil physical property cluster, soil chemical property cluster, and vegetation cluster), in which the soil chemical property cluster owned the highest clustering coefficient and the largest number of triangles, and it was most stable and the interaction within the cluster was strongest. The soil-vegetation network was stable and the connectivity of the network had robustness to node failures. The scale of the network became larger and the network became tighter and more stable with the increase of reclamation time. Some measures should be conducted to promote vegetation restoration by improving important soil nodes, e.g., surface soil covering, applying organic fertilizer, and planting nitrogen-fixing plants.

Long-term underground coal mining activities results in severe surface deformation and land subsidence, altering soil physical properties significantly. Soil particle size distribution (PSD) is a fundamental physical attribute affecting many other soil properties. Therefore, understanding the variability of PSD is crucial to conduct targeted land rehabilitation. In present study, a novel method combining multi-fractal theory and geostatistics was advanced to characterize the spatial variability of soil PSD in a coal-mined subsidence area. Three independent field plots, i.e., one unmined plot (UMP), one subsided plots (SUP), and one reclaimed plot (RCP), in NO.3 Pingshuo Anjialing underground coal-mine in Shanxi province of China, were selected to perform this study. Four multi-fractal attributes of PSD of individual soil samples, i.e., D(0), D(1), Δα(q) and Δf(α), in three plots were calculated, and geo-statistics was employed to quantify the spatial variability of multi-fractal attributes of PSD. This combining method showed some advantages in characterizing the variability of soil PSD compared to single multi-fractal, single geo-statistics or traditional statistics, and it can characterize the spatial variability of overall PSD characteristics in detail, quantifying the spatial variability of soil PSD range, PSD concentration degree, PSD non-uniformity, and PSD non-symmetry. The soil PSD range, PSD concentration degree, PSD non-uniformity and PSD non-symmetry in this underground coal mining area didn't present a high spatial variability. Combining multi-fractal theory and geostatistics is an effective method to characterize the spatial variability of soil PSD in underground coal-mine area, and this method is universal and can be popularized and applied in other unmined areas.

Opencast coal mining has a series of consequences on land resources and places enormous pressure on the ecological environment. Stripping, excavation, transportation and dumping have different effects on soil physical, chemical and biological properties. Moreover, the reconstructed landscape produces increased small-scale spatial heterogeneity of mined soils. Currently, growing concerns for the negative consequences of mining have highlighted the importance of reclamation in minesoil studies. This review has examined the mechanisms of coal mining and reclamation that affect soil properties (physical, chemical, biological) and described soil development in reclamation, with an emphasis on the reclaimed minesoil (RMS) properties of reclamation sites. The major conclusions of this review were: (i) The randomness of soil dumping increased the heterogeneity of minesoil properties, which in turn increased the complexity of reclamation practice. (ii) The negative or positive consequences of mining and reclamation processes on RMS need to be recognized by scientific observations such as soil property multi-index analysis and soil chronosequences, on which the minesoil reconstruction practice are based. (iii) Five phases of reclamation (i.e., geomorphic reshaping, soil reconstruction, hydrological stability, vegetation restoration, and landscape rebuilding) should be considered as a comprehensive system for the reconstruction of minesoils. (iv) The application of new technologies (e.g., micro-terrain reshaping and soil non-destructive detection) and new studies (e.g., systematic study, rebuilding animal habitat, and biodiversity research) to minesoil recovery practice would enhance the new concepts of land reclamation and ecological restoration in mining areas.

The environmental performance was assessed for a wardrobe made from hybrid modified ammonium lignosulfonate/wood fiber composites (HWC). The HWC wardrobe system involved four subsystems, namely the raw materials supply, energy consumption, wardrobe manufacturing, and transportation. A comparative life cycle assessment of a wardrobe built from conventional medium-density fiberboard with three primary damage categories was also performed. The results suggested that the HWC composites were a more sustainable material compared with conventional boards. The raw materials supply and energy consumption influenced the three primary damage categories. Climate change on human health, particulate matter formation, fossil depletion, and human toxicity had a dominant contribution to the overall environmental impact. Also, a sensitivity analysis was performed with a focus on using wood waste as a raw material and on the different conditions for the modification of lignosulfonate for manufacturing HWC. The results indicated that the use of wood waste and an appropriate amount of unmodified lignosulfonate as a binder aids in efficient HWC production for wardrobes. These results can help to improve HWC wardrobe technology and in choosing the appropriate wardrobe system.

The soil organic carbon (SOC) stock is severely affected by the exploitation of opencast coal mines, and the relationships of factors influencing SOC stock are complex. The influence factors of SOC stock in reclaimed lands in opencast coal mines are unclear, and the existing models can not characterize the complex relationship of SOC stock sufficiently. This paper analyzed the influence factors of SOC stock using complex network theory in the Antaibao opencast coal-mine in Shanxi province of China. An investigation of the soil, topography and vegetation in 50 reclaimed plots was performed. Soil factors, i.e., rock content (RC), total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil bulk density (BD), soil water content (SWC), SOC stock, electrical conductivity (EC), clay content, silt content, sand content and pH, vegetation factors, i.e., above-ground biomass (AGB), tree volume (TV), herb coverage (HC), canopy density (CD), and topography factors, i.e., slope, slope aspect (SA) and slope position (SP), were selected as the nodes, and the relationship among the various factors were considered as the edges to construct a complex network using Gephi. The network characteristics, including degree, betweenness and average shortest path so on, were calculated. SOC stock, SWC and BD played an important role in the complex network of SOC stock. The SOC stock was affected by three clusters: soil texture cluster, soil physicochemical property cluster, and vegetation-topography cluster. SOC stock network was not stable and was sensitive when some important nodes were disturbed. The complex network theory could be used to analyze the influence factors of SOC stock. This study provided a reference for selecting rational land reclamation measures to increase soil carbon stock.

The reasonable strategies of payment for ecosystem services (PES) play a key role in solving the contradiction between ecological protection and economic development in coastal cities. However, at present, the payment efficiency is relatively low and the determination method of PES is lack. Therefore, in this study, the Jimo district of Qingdao city in China, a typical coastal city, was selected as study area, and the equivalent factor method and marine ecological capital assessment method were used to obtain terrestrial and marine ecosystem services value (ESV) and its tempo-spatial variations from 2010 to 2018. Moreover, the payment efficiency of the sea area and 15 towns over 8 years was measured using the Super-efficient SBM-DEA model based on undesired output. ESV presented a clear reduction over 8 years. The marine ecosystem provided the main service value, and waste treatment, water regulation, and soil formation were the top 3 main functions in the land ecosystem. Regulating services provided the highest component among all functions. The high-value areas were mainly distributed in the northeast and northwest regions and the low-value areas were in the south-central regions. The average payment efficiency of the sea area and 15 towns over 8 years shown a stable trend at a low level. On the basis of the evaluation of ESV and efficiency, a new possible payment scheme including payment order and quota was proposed. The total quota of marine ecosystem was 5.226 billion RMB (88% of the total) and of terrestrial ecosystem was 0.713 billion RMB. Tian Heng, Jin Kou, Yi Fengdian, and Ling Shan are the first 4 priority towns, with compensation amounts of 0.205, 0.083, and 0.063 billion RMB respectively, while the last 3 towns are Tong Ji, Huan Xiu, and Chao Hai accounting for 6.02% of the total. The theoretical payment total quota was 5.939 billion RMB, and which accounted for a low proportion of local GDP. The study can provide some recommendations for making the reasonable and feasible payment schemes for ecosystem services in coastal city, and it is feasible in the practice of ecological environment protection and sustainable development.

Soil and vegetation, as the basic structural unit of artificial ecosystems, play an important role in ecological restoration in opencast coal mining areas, and both exhibit a complex interaction. However, the traditional method cannot well characterize the inter action between the soil and vegetation. In order to reveal the interaction between soil and vegetation in the reclaimed area of opencast coalmine, and explore the interaction mechanism between soil and vegetation, the soil and vegetation data from 70 reclaimed points in Antaibao and Anjialing opencast coal mines in Shanxi province of China were selected to conduct an investigation study. Ten soil and three vegetation indicators were determined, and the joint multifractal method was innovatively introduced to characterize the relationships of soil and vegetation on multiple scales using joint multifractal spectra and grayscale images. The interaction between soil and vegetation can be clearly obtained using the joint multifractal method. The canopy density was negatively correlated with soil bulk density, silt content, and pH; whereas, it was positively correlated with rock content, sand content, total nitrogen, soil organic matter, available phosphorus, and available potassium content. The average diameter at breast height was negatively correlated with soil bulk density, clay content, and pH; however, it was positively correlated with silt content, sand content, total nitrogen, soil organic matter, available phosphorus, and available potassium content. The herb coverage was negatively correlated with rock content, silt content, clay content, pH, soil organic matter, available phosphorus and available potassium content. Soil bulk density and clay content showed negative correlation with herb coverage. Compared to the traditional method, the novel joint multifractal method can more accurately charecterize the correlations from multiple scales. This novel method can be used to study the interaction between soil and vegetation.

Soil compaction resulted from heavy machineries in opencast coal mine areas alters soil macropore characteristics then affects soil hydraulic properties. Additional information related to hydraulic characteristics is needed to assess the effects of soil reconstruction to improve the soil quality. The aim of this study was to determine the hydraulic properties and macropore characteristics of compacted soil by simulation tests and CT scanning in laboratory and to explore the response of soil hydraulic properties to soil macropore characteristics. In this study, the disturbed soil samples from the dumping area of Pingshuo opencast coal mine of China were collected. The soil samples were processed in designed bulk density (BD) from 1.30 g·cm-3 to 1.70 g·cm-3, and the soil hydraulic properties, including soil-water characteristic curve (SWCC), saturated hydraulic conductivity ( Ks), soil moisture diffusivity (D(θ) ), field capacity (FC), wilting coefficient (WC) were measured and the soil macropore characteristics were obtained using CT scanning in laboratory. The path analysis method was applied to analyze the effect of macropore characteristics on soil hydraulic properties. Soil compaction resulted in severe effects on soil hydraulic characteristics and macropore properties. Under same soil suction, the water contents remained in soil decreased with increasing compaction. Soil-water holding capacity, soil saturated hydraulic conductivity, and soil water diffusivity decreased with increasing BD. The explanatory variables (average euler number (AEN), macropore throat number (PTN), and macropore fractal dimension (PFD)) were main determinants of soil-water holding capacity, and the indirect path coefficient of macroporosity. The effects of average euler number (AEN) and macropore fractal dimension (PFD) on soil infiltration properties were relatively high. The BD of 1.4 g·cm-3 was a critical point of affecting macropore properties then affecting soil hydraulic properties, and some soil reclamation measures should be conducted to make BD

Effects of nanoplastics at low level on the marine primary producer are largely unclear. To assess the potential risk of nanoplastic pollution, this study exposed marine green microalgae Platymonas helgolandica to 20, 200, and 2000 μg/L 70-nm polystyrene nanoplastics for 6 days. Nanoplastics significantly inhibited the growth of P. helgolandica during the first 4 days of exposure, and elevated heterocyst frequency was observed in 200 and 2000 μg/L exposure groups in the early exposure stage. Exposure to 200 and 2000 μg/L nanoplastics for 4 days increased the membrane permeability and mitochondrial membrane potential, and decreased light energy used in photochemical processes of microalgae. Moreover, clear morphological changes, including surface folds, fragmentation, aggregation cluster, and rupture, in the microalgae exposed to nanoplastics were observed under scanning electron microscope and transmission electron microscope. These results demonstrate that nanoplastics could reduce the microalgal vitality by the damage on cell morphology and organelle function.

A large quantity of flue gas desulfurization gypsum (FGDG), a by-product of removing sulfur from combustion gases in coal-fired power generation plants, was produced in the world. Improving saline-sodic soils with FGDG is one of the effective ways to utilize FGDG. However, the use of FGDG has severe impacts on the environment. With growing application of FGDG for improving soils, there is an increasing necessity to analyze the environmental impact on the entire agricultural application process. Life cycle assessment (LCA) is useful for comparing the potential risks of different environmental impact categories and stages. Traditional LCA methods have some limits in comparing various schemes, while the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) has its unique advantages in multi-objective decision-making. Therefore, this study identified and compared the environmental impacts of four alternative schemes in three stages using LCA combined with TOPSIS. In this study, the environmental impact of improving 1 ha saline-sodic soil was assessed, and a sensitivity analysis was conducted to analyze the effects of the changes in heavy metals in FGDG and in irrigation. The highest impact category was water consumption, with a weighted environmental impact value of 2.20 × 10−1 and a contribution rate of 42.216%. The second-highest environmental impact category was soil toxicity, with a weighted environmental impact potential value of 8.04 × 10−2 and a contribution rate of 15.429%. The soil toxicity was mostly from the application stage, while the water and energy consumption were mainly from the irrigation of planting stage. Acidification and eutrophication were mainly from fertilizer applications. Effective measures, including scientific use of fertilizers and pesticide, reasonable irrigation and strict control of heavy metals in FGDG should be employed to mitigate environmental risks during the agricultural application of FGDG. This study constructed a framework for the environmental impacts of improving saline-sodic soils with FGDG integrated with TOPSIS, and can be considered as an effort to advance the application of LCA.

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 ( D 1 ), difference between capacity dimension minus entropy dimension ( D 0 -D 1 ), variation degree of generalized dimension spectra (Δ D ), width of singularity spectra (Δ α ) and symmetry of singularity spectra (Δ f ) can reflect different aspects of the soil pore distribution characteristics. Compared to unmined soils, the multi-fractal parameters of soil pore distribution ( D 1 , D 0 -D 1 , Δ D , Δ α and Δ f ) significantly decreased after mining and dumping, and soil micropores dominated with uniformity. However, D 1 , D 0 -D 1 , Δ D , Δ α and Δ f 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.

Purpose: The use of heavy machinery in mining areas increases during mining and dumping of waste soils, causing severe soil compaction and potentially affecting soil recovery. This study aimed to capture the features of complex compacted soil pore structure using computed tomography (CT) and to quantify soil pore distribution properties based on Minkowski theory. Materials and methods: A total of 45 cylindrical soil columns were extracted from different soil layer at 5 sampling sites that differed in compaction level in Pingshuo opencast coal mine in Shanxi Province of China. The penetration resistance at these sites ranged from 27.3 to 1023.1 kPa. Three-dimensional reconstruction software VGStudio was used to obtain the morphological characteristics (pore volume density, VD; surface density, SD; mean curvature density, MCD; and Euler number, EN) of soil pores after processing the X-ray scanned image. Results and discussion: Compaction generally reduced VD, SD, and MCD, which ranged from 0.10 to 0.20, 2.23 to 2.80 mm 2 mm −3 , and 10.75 to 15.64 mm mm −3 respectively in undisturbed site P0, whereas, they ranged from 0.02 to 0.07, 0.13 to 0.60 mm 2 mm −3 , and 1.61 to 4.27 mm mm −3 respectively in highly compacted site P4. The three index exhibited the similar trend, and decreased with the increase of compaction level. Soil compaction had positive effects on EN, which was low at the depth of 20- to 40-cm layers but showed an increasing trend with increasing soil compaction level. The value of EN varied from 28,878 to 129,861 in P0, whereas it varied from 1,169,967 to 2,281,998 in P4. Conclusions: All of macroporosity, mesoporosity, and microporosity were significantly affected by heavy machinery compaction, among which macroporosity exhibited the maximum decrease in P4 compared to that in P0 (P0 ranged from 14.2 to 26.4% and P4 ranged from 0.2 to 1.4%). The soil compaction in mining area significantly affected soil properties, thus artificial methods such as fertilizer application and deep tillage were needed.

It is necessary to analyze the environmental impact of the entire process of coal-fired power generation to take effective measures for controlling energy consumption and reducing pollutant emission. However, very few studies have examined the coal mining, washing and transportation stages in the life cycle of coal-fired power generation and it's environmental cost. In this study, the life cycle assessment (LCA) method was adopted to analyze the environmental impact of coal-fired power generation in China. Further, the relevant cost theory was used to calculate the resource consumption cost and external environmental cost of coal-fired power generation. The key environmental impact category was smoke and dust, and the main emissions were CO2, CO, SO2, TSP, COD, and boiler ash. The emissions with high environmental cost were coal, SO2, COD, and boiler ash. The environmental cost at the power generation stage was the highest, with a value of $50.24. The resource consumption cost and external environmental cost per unit of MWh power in the life cycle was $46.01 and $22.90, respectively. Upgrading the facilities for emission reduction, improving emission standards of pollutants, and strengthening process management of coal-fired power generation are effective ways to reduce the burden on the environment.

Underground coal-mining results in severe land subsidence then changes soil nutrient distributions. Soil organic matter (SOM) and total nitrogen (TN) are critical indicators of soil quality and play a key role for plant growth. However, fewer scholars pay attention to the soil nutrient distributions in mining subsidence areas. In this study, a total of 64 soil sampling points, taken from 4 different plots (one unmined plot, two subsided plots and one reclaimed plot), were collected from No.3 Anjialing underground coal mine in the loess area of China. SOM and TN at the depths of 0–20, 20–40, 40–60 and 60–80 cm in these sampling plots were measured. The classical statistics and geo-statistics were used to analyze the vertical and horizontal spatial variability of SOM and TN. The mechanisms of the effects of coal mining subsidence on soil nutrient distribution were revealed based on the distribution of the surface cracks of subsided plots. All of SOM and TN at the depth of 0–20 cm in subsided plots were less than those in unmined plot. Below the depth of 20 cm, TN in subsided plots were higher than those in unmined plot and SOM were less than those in unmined plot. SOM in reclaimed plot were higher than those in subsided plots; however, TN did not exhibit a clear regularity. Land subsidence increased horizontal spatial heterogeneity of SOM and TN distributions. The crack width, crack depth and the distance between sampling point and edge of crack were the main influence factors resulting in horizontal spatial heterogeneity of SOM and TN. This study can provide a theoretical and technical reference for land rehabilitation in subsided lands in loess area.

Over the past few decades, there has been wide interest in developing strategies for the utilization of flue gas desulfurization gypsum (FGDG), a by-product of scrubbing sulfur from combustion gases in coal-fired power generation plants. FGDG has applications in agriculture due to its function in the remediation of soil quality and crop growth. It is often economical to use FGDG as a soil amendment; however, compared to other industries, the utilization of FGDG in agriculture is very limited. A comprehensive review of numerous studies in the last few decades was conducted in this paper, which systematically covered the importance, scope, function, effect and risk regarding the utilization of FGDG in agriculture. As a remediation material, FGDG has many benefits in agriculture applications, such as improving soil physicochemical properties, controlling soil and nutrient loss, supplementing trace elements for soil and increasing crop yield. However, FGDG also contains a number of toxic trace elements. Therefore, proper attention should be paid to some important areas related to FGDG utilization, such as long-term studies of the impact of FGDG on soil health, heavy metal uptake, crop growth and quality, and continuous monitoring of the health of soil and water. The problems of salt accumulation and heavy metal toxicity due to excess application should also be addressed when FGDG is used in agriculture. Moreover, some measures and standards for the practical application of FGDG need to be proposed to promote the utilization of FGD gypsum in agriculture.

Coal mining activities can lead to large-scale and high-intensity ecological disturbances, which not only destroy a large amount of land resources, but also cause ecological disturbances and environmental pollution problems, such as regional surface erosion and vegetation destruction. As one of the fourteen large coal bases in China, the North Shanxi coal base is in the ecologically fragile Loess Plateau. Under the influence of coal mining and urbanization, the ecosystem has been seriously affected. Vegetation is a direct or indirect driver of ecosystem change. In this study, Sen's slope analysis and Mann-Kendall trend test were carried out to characterize the trend and significance of vegetation coverage change from 1987 to 2020 based on remote sensing images, and the future tendency was predicted using the Hurst index method. Moreover, the effects of natural and human factors on vegetation coverage were explored. From 1987 to 2001, the vegetation coverage showed a downward trend, and it continued to rise from 2001 to 2020. The overall vegetation coverage showed an upward trend from 1987 to 2020, and the improvement areas are mainly concentrated in the southwest and southeast mountains. Future vegetation coverage in the North Shanxi coal base showed strong randomness. Regional vegetation coverage changes were closely related to climate factors, and the policy of “grain for green” have also played an important role, while coal mining didn't present great impact on vegetation coverage changes. Therefore, relevant land use policy recommendations are put forward.

With the rapid development changes and the special land-use patterns, coal-based cities (CBCs) have faced many critical sustainability issues such as the effective use of land resources, the mitigation of land supply-demand contradictions. How does the development of CBCs in China affected local land-use changes and what status does each land type occupy? The relevant mechanisms are not clear. Shuozhou City, a typical growth CBC in China, was therefore selected as the research area to investigate the land use evolution by introducing the theory of land use ecological niche (LUEN). The dynamic changes of land use from 1990 to 2018 were analyzed, and cultivated land played a significant role in the process of land transformation with the highest utilization degree, followed by grassland and construction land. The cultivated land and mining land occupied the economic niche, construction land occupied the social niche, and forest land, grassland, and water area occupied the natural niche. From 2010 to 2015, construction land and mining land occupied the prevailing position of the land-use system. The substantial expansion and compression of the land use ecological niche in Shuozhou City were in the early stage of city development, and there was not a major change in the later stage. In general, the spatial distribution of land use ecological niche was in the east-west direction. Therefore, the production function zone, living function zone, and ecological function zone were delineated. The status, role, and function of land use type should be prioritized when developing land-use planning, considering the mechanisms of land-use change. Governments should actively break through the restrictions of coal resources mining on land use change while giving full play to the role of land resource assets in promoting sustainable development.

Land subsidence caused by underground coalmining gives rise to severe surface deformation and results in a number of soil cracks, which markedly affect soil hydraulic properties; moreover, land rehabilitation is an effective measure to restore the ecological function of impacted lands. To analyze the effects of land subsidence and rehabilitation on soil hydraulic properties, an underground coalmine in the Loess Plateau of China was selected to conduct a field plot experiment. Four plots were designed, including one unmined plot (UMP), two subsided plots (SPI and SPII) and one rehabilitated plot (RHP), and 16 sampling points were located in each plot. The bulk density (BD), soil moisture retention curve (SMRC), field capacity (FC), saturated hydraulic conductivity (Ks) and soil disintegration rate (SDR) at the depths of 0–20 cm, 20–40 cm, 40–60 cm and 60–80 cm at each sampling point were measured, and soil pore size distribution (PSD) based on SMRC was analyzed. The correlation analysis among soil hydraulic properties and the path analysis of effects of subsided cracks on the hydraulic properties were carried out in this study. Land subsidence increased the variability of soil hydraulic properties; whereas, they became relatively uniform after land rehabilitation. Land subsidence significantly altered soil hydraulic properties, increasing BD, Ks, SDR and soil micropores and decreasing FC; however, land rehabilitation can improve soil hydraulic properties and increase the use efficiency of soil water, decreasing BD, Ks, SDR and increasing FC and soil macropores. The cracks related to subsidence and vegetation had significant effects on soil hydraulic properties, especially BD; the crack width and vegetation coverage had a marked effect on BD.

Post-mining dumps are typical artificial landforms, with original natural features of soil, topography and vegetation radically altered, and soil and water conservation capacity declined accordingly. In this study, the geomorphic characteristics and soil erosion of reconstructed landforms and their relationships in opencast coal mines are studied. The elevation relief features were described using multi-fractal methods, soil erosion rates were evaluated utilizing the revised universal soil loss equation (RUSLE), and the correlations between geomorphic multi-fractal parameters and soil erosion rate were analyzed within a study area of three soil dumps in the Shanxi Pingshuo Antaibao opencast coal-mine of China. The results show that reconstructed landform in opencast coal mines have multi-fractal characteristics. Generalized dimensions (D0, D1, ΔD and D1/D0) and singularity spectra (α0, Δα and Δf) quantify reconstructed geomorphic features. Soil erosion in the sub-areas is slight, indicating that reclamation measures have alleviated soil erosion exacerbated by mining. Geomorphic multi-fractal parameters reflect the differences of soil erosion rate, the increasing trend of D0, D1 and α0 are consistent with that of average annual soil loss rate. It is feasible to apply these parameters to reflect soil erosion of reconstructed landforms. This study provides a new perspective for portraying the reconstructed geomorphic features and soil erosion on opencast coal-mine dumps.

Excessive land use has a series consequences on the degradation of land function and exerts tremendous pressure on the ecological environment. Farming, mining, and heavy metal pollution have resulted in many negative effects on soils. Biochar has become a hot research topic in the fields of agriculture, environment, and energy as an environmentally friendly soil improver in recent years. The application of biochar for both agricultural and environmental benefits has been studied and reviewed extensively. However, there are limited reviews on the structures of biochar and other biochar applications. This paper provides an overview of recent advances in the effects of the various physicochemical properties of biochar and biochar utilizations including its use as catalyst, soil amendment, water retention, contaminant adsorbent, gas storage, ion exchange, and soil microbial activity. Discussions on biochar on the physical, chemical, biological properties after amendment to the soil and preparation condition. However, the negative effects of biochar in preparations and applications need to be recognized through scientific observation and research. It is anticipated that further research on biochar amendment will increase the understanding on the interactions of biochar with soils, review the negative effects of biochar and it should be alleviated as much as possible.