Mining Subsidence Land Research Articles

Habitats generated by the restoration of coal mining subsidence land differentially alter the content and composition of soil organic carbon.

The content and composition of soil organic carbon (SOC) can characterize soil carbon storage capacity, which varies significantly between habitats. Ecological restoration in coal mining subsidence land forms a variety of habitats, which are ideal to study the effects of habitats on SOC storage capacity. Based on the analysis of the content and composition of SOC in three habitats (farmland, wetland and lakeside grassland) generated by different restoration time of the farmland which was destroyed by coal mining subsidence, we found that farmland had the highest SOC storage capacity among the three habitats. Both dissolved organic carbon (DOC) and heavy fraction organic carbon (HFOC) exhibited higher concentrations in the farmland (20.29 mg/kg, 6.96 mg/g) than in the wetland (19.62 mg/kg, 2.47 mg/g) or lakeside grassland (5.68 mg/kg, 2.31 mg/g), and the concentrations increased significantly over time, owing to the higher content of nitrogen in the farmland. The wetland and lakeside grassland needed more time than the farmland to recover the SOC storage capacity. The findings illustrate that the SOC storage capacity of farmland destroyed by coal mining subsidence could be restored through ecological restoration and indicate that the recovery rate depends on the reconstructed habitat types, among which farmland shows great advantages mainly due to the nitrogen addition.

Wetland Functional Area Division Method: A Correlation Analysis of Water Quality and Landscape Structure

The purpose of this study is to provide a clearer idea for the optimization of wetland functional areas and a new method for the identification and analysis of wetland functional areas under the background of the latest Wetland Protection Law in China. This study selected Pan’an Lake Wetland, the first national wetland park built in coal mining subsidence land in China, as the research object. By constructing a “Water-water-landscape-function” (WLF) model, combined with landscape pattern index and Nemerov pollution index method (NPI), the differences in water quality and landscape structure of different functional areas were analyzed. Then, Pearson’s Correlation Analysis and Redundancy Analysis are combined to quantitatively analyze the correlation between water quality environment and landscape structure. Finally, Inverse Distance Weighting (IDW) was introduced to help study the spatial difference in water quality in different functional areas. This study lasted for one year. Twelve water quality sampling points were set up, and 216 effective samples were collected monthly for one year. The results showed that: (1) the ratio of built-up land and cultivated land area had a high impact on water quality indicators in each water period, especially the increase in cultivated land patch density would increase the risk of TN and TP losing to surrounding water bodies; (2) the lakes and rivers in the wetland park have good ecological effects and should be widely used in various functional areas; (3) the degree of landscape fragmentation was negatively correlated with the overall water quality, while the degree of landscape agglomeration and landscape diversity were positively correlated with the overall water quality; (4) ecological corridors should be established between WCA and WRA, artificial corridors should be established between MEA and LEA, and ecological interception should be set between MEA and WRA; and (5) the “Water-quality-landscape-function” (WLF) model is an effective tool for the analysis and optimization of wetland functional areas, which provides a reference for the new round of wetland planning in China.

Sediment settlement rate and consolidation time of filling reclamation in coal mining subsidence land

With the continuous growth of the population and the continuous reduction of cultivated land, China’s food security is greatly threatened. In addition, China’s coal mining has been mainly underground mining, causing land subsidence and damaging existing cultivated land. This effect intensifies the contradiction between the growth of the risk population and the reduction of cultivated land. The reclamation of mining subsidence land with Yellow River sediment is often used as an effective way to improve the recovery rate of cultivated land. Shortening the reclamation time and realizing continuous filling are significant issues. The work presented in this paper studied the sediment settlement rate and consolidation time by combining theory, field filling and reclamation tests and numerical simulations. A field filling test study was carried out in the lowlands of Jibeiwang Village, Qihe County, Shandong Province, China. By calculating the drainage consolidation time, the consolidation factor of 0.015656 m2/d, and the time factor for sediment consolidation of 0.575 were determined. The sediment consolidation time for this test was 9.18 days. The calculation of sediment deposition rate and consolidation time is of great practical significance to guide the Yellow River sediment filling, realize continuous filling, and save reclamation time and cost.

Shifts in Vegetation-Associated Microbial Community in the Reclamation of Coal Mining Subsidence Land

The recovery of soil microbial community is important for reclamation success in coal mining subsidence land. This study aims to investigate the relationship between soil microbes and vegetation sp...

Calculation of Residual Surface Subsidence Above Abandoned Longwall Coal Mining

Exhausted or abandoned underground longwall mining may lead to long-term residual subsidence on surface land, which can cause some problems when the mined-out land is used for construction, land reclamation and ecological reconstruction. Thus, it is important to assess the stability and suitability of the land with a consideration of residual surface subsidence. Assuming a linear monotonic decrease in the annual residual surface subsidence, the limit of the sum of the annual residual subsidence factor, and continuity between surface subsidence in the last year of the weakening period and the residual surface subsidence in the first year, we establish a model to calculate the duration of residual subsidence and the annual residual surface subsidence factor caused by abandoned longwall coal mining. The duration of residual surface subsidence increases with the increase in mining thickness as well as the factor of extreme residual subsidence. The proposed method can quantitatively calculate the annual residual subsidence, the accumulative residual subsidence, and the potential future accumulative residual subsidence. This approach can be used to reasonably evaluate the stability and suitability of old mining subsidence areas and will be beneficial for the design of mining subsidence land reclamation and ecological reconstruction.

Land Subsidence in a Coal Mining Area Reduced Soil Fertility and Led to Soil Degradation in Arid and Semi-Arid Regions.

Underground coal mining in western China causes heavy land subsidence and alters the soil ecology. However, the effects of land subsidence on soil fertility are not currently known, and the key factors governing its impact remain unclear in sandy land. We investigated the effects of land subsidence induced by underground mining on the soil quality in western China. Soil samples were collected at 0–15 cm and 15–30 cm from control and subsidence areas in three coal mines. The results showed that the soil water content (SWC), clay and silt percentage, total nitrogen (TN), dissolved organic carbon (DOC), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), available phosphorus (AP), and available potassium (AK) of the subsidence areas were significantly lower than those of the control areas. The saccharase, urease, and alkaline phosphatase activities in the subsidence areas decreased compared to those in the control areas, while the sand percentage of soil tended to increase. Soil nutrient contents, bacterial quantities, and activities of soil enzymes were positively correlated with SWC. Redundancy analysis (RDA) showed that the soil particle size distribution, SWC, and electrical conductivity (EC) were the major environmental factors driving changes in soil properties. These results indicated that land subsidence induced by coal mining caused losses in surface soil water and nutrients, and ultimately led to soil quality degradation. Therefore, the reclamation of mining subsidence land might be necessary, especially in arid and semi-arid areas.

Assessment of several typical physical properties of reclaimed farmland filled with Yellow River sediment in Jining, China

Land subsidence caused by underground coal mining is one of the most prominent environment problems in China. The reclamation of mining subsidence land with Yellow River sediment was considered to be feasible, but its effectiveness needs to be verified. An integrated reclamation technology with Yellow River sediment was evaluated using a comparison of actual crop production soil profile analysis in Jining City, China. The results indicated that reconstructed soil profile of the reclaimed farmland was less effective in retaining water and in supporting plant growth than that of the unaltered farmland. Some measures are proposed, such as reducing the drainage velocity to allow sedimentation and retention of the clay and silt, changing the techniques of filling the Yellow River sediment and increasing the organic matter content in the soil layers to improve the capacity to retain water in the reclaimed farmland.

Assessment of chemical properties of reclaimed subsidence land by the integrated technology using Yellow River sediment in Jining, China

Land subsidence is one of the most prominent environmental problems in China. Chemical properties of reclaimed subsidence land by the integrated reclamation technology using Yellow River sediment were assessed. Reclamation engineering of mining subsidence land was conducted, and representative soil samples of the reclaimed farmland (SR) and nearby unaltered farmland (CK) were collected from Jining City, Shandong Province. Soil chemical properties, including pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), extractable phosphorus (EP) and potassium (EK), and eight heavy metals were measured. The results indicate that more than 95 % of mining subsidence lands can be restored to farmland, which indicates the integrated reclamation technology with Yellow River sediment was feasible. The soils of SR and CK were alkaline but non-saline. The contents of TN, EP, EK and OC of SR were less than those of CK. Cd and Hg were not detected in any soil, and the contents of Pb, Zn, Cu, Cr, Ni and As of all soil layers of SR and CK were less than the maximum contaminant values of the second level to maintain human health and third level to protect plant normal growth as suggested in the standard for soils of China. Some improved methods of the integrated reclamation technology are suggested, such as draining water after settling of the water–sediment mixture in the reclamation strip for several days (>48 h) to increase deposition of more clay and silt in SR. The return of wheat or maize residue is recommended to improve both the fertility and plant-available water capacity of SR. Conventional tillage of the reclaimed land will likely improve productivity as the sand, silt and clay particles become an integral, living, soil body.

Application of remote sensing technology to microbial reclamation

Microbial reclamation is an effective means for ecological restoration in coal mining. Remote sensing,especially hyperspectral remote sensing,can rapidly and precisely determine the growth status of plants in the field and the improvement of soil properties,thus providing important technical support for implementation of microbial technology to land restoration and ecological environment rehabilitation in coal mining. This paper summarized in detail the application of remote sensing to monitoring the plants recovery,reclamation of waste dump of tail slag and subsidence and pollution of heavy metals in reclaimed areas,and the application of microbial technology to improving the environment of coal wastes,managing mining subsidence land and restoring land polluted by heavy metals. Some ideas of remote sensing technology applied in microbial reclamation for future research were discussed in this paper,which could provide an important reference and guideline for quick,accurate and undamaged monitoring of growth of plants reclaimed with microorganism and estimation of microbial technology implemented in ecological restoration in coal mining in the future.

Role of the different planting age of seabuckthorn forests to soil amelioration in coal mining subsidence land

To investigate the effects of seabuckthorn (Hippophae rhamnoides) on soil amelioration, using the space replacement method, soil physical and chemical indexes as well as the microorganism quantity and soil enzyme activities were analyzed. The results showed that: the soil bulk density of surface soil decreased and soil porosity and field capacity increased after afforestation with seabuckthorn. The plant was found to effectively reduce the soil pH, increase the soil conductivity, soil organic matters and available nutrients. Soil microorganism quantity, soil enzyme activities were both higher in 0–20 cm layer than in 20–40 cm layer. With the increase years of remediation with seabuckthorn, the quantity of soil microorganism and enzyme activities were increasing to a higher level 5 to 8 years later. Our study indicates that seabuckthorn can effectively improve soil physical and chemical properties, increase the quantity of soil microorganisms and enzyme activities, which is of great significance for the ecosystem restoration in mining areas.

Introduction of a New Reclamation Technology in Mining Subsidence Area by Yellow River Sediment

The research introduces a kind of new technology of utilizing sediment from the Yellow River for filling and reclamation of coal mining subsidence area. Through analyzing the water and sediment conditions in downstream of the Yellow River for filling subsidence, detail design on sediment fetching position, scale, method, equipment, pipe and pump station, technical costs assessment and economic benefits analysis are conducted to find a new less cost and big benefit way to comprehensively solve the problems of sediment in the Yellow River and coal mining subsidence land.

Ecological Restoration of Abandoned Mine Land in China

Abstract: Mining activities produced a lot of abandoned mine land. This paper introduced the theoretical and technical progress of ecological restoration of surface coal mines, mining subsidence land and coal waste piles in China and discussed some key problems for research in the future. Ecological restoration of abandoned mine land was related to many disciplines, and multi—disciplinary theories might make great contributes to it. Some practical techniques of ecological restoration of abandoned mine land and their demonstration bases in China were introduced. Ecosystem succession process and mechanism, structure optimization of land use and new technologies of ecological restoration of abandoned mine land should be focused on in research activities.

Evaluation to Damage Situation of Coal Mining Subsidence Land in Mountainous Area Based on MSPS and GIS

Take Songzao mining area in Chongqing for example, the damage situation of coal mining subsidence land in mountainous area was studied, optimum evaluation indexes for damage situation of land was selected by discussing existing evaluation indexes, and the contestant standard formed by using Delphi method, and grade of damage situation of coal mining subsidence land was confirmed by overlying analytical method of GIS raster data. The results showed that the degree of land destruction most belong to slight and middle damage, the relatively serious damage forms were collapse pit and collapse crack, and the degree of land destruction tends to weaken gradually from mining center to edge. There was a positive correlation between the degree of land destruction and mining degree.

THE ENVIRONMENT AND THE UTILIZATION THE STATUSOF THE SUBSIDENCE AREA THE IN XU ZHOU, YAN ZHOU AND HUAINAN AND HUAIBEI REGION OF CHINA

The coal mining subsidence land in East China was mainly distributed in Huanghuaihai Plain such as Kailuan, Huainan, Huaibei, Xuzhou, Pingdingshan, Yanzhou and other coal mining area. At present, the surface subsidence caused by underground mining area could reach 13000 km2, and over half of which was concentrated in the plains, especially Xu Yan, Huainan and Huaibei region. Surface collapse of coal field is one kind of geological disaster with great hazard, which may result from distortion and breakout of overlying strata that lose their support after underground coal beds are excavated in a large area. Due to the little dip angle coal seam, thick sediment loose layer, high phreatic water level on the flat XUYAN, Huainan and Huaibei Plain, and the the collapse land was lower than surface, the different depth and different size of subsidence water ponds were formed. On the influence of precipitation and surface water, XUYAN, Huainan and Huaibei coal mine subsidence showed with the appearance of water-logged area or marshland. With the change of precipitation, topography and geological condition of coal seam, the depth and dimension of the subsidence water area increased gradually, and the arid and seasonal water-logged area were decreasing gradually, and on the contrary, the subsidence flat marshland and the perennial shallow and deep waterlogged area was increasing gradually.