Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the h...Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the hypothesis of speedy revegetation. Root colonization and spore density of arbuscular mycorrhizae (AM) were lowest in plants seeded directly on slopes of the overburden (coal mine dump). At flat surfaces, the mycorrhizal colonization in plant species was higher than that observed at slopes. In other revegetation models, i.e., tree monoculture, tree monoculture + crop species (agroforestry), and two strata plantations (combination of different plant species), maximum AM colonization was recorded for tree species grown along with crop species. This was followed by two strata plantations and tree monoculture. In two strata plantations three categories of AM associations were recognized: 1) every plant in the combination, possessed high mycorrhizal association, 2) only one plant in the combination possessed high mycorrhizal association, and 3) none of the plants in the combination possessed high mycorrhizal association. Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae, and can be used as the effective tool in rehabilitation of the degraded ecosystems.展开更多
The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanx...The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.展开更多
Purpose–This study solves the key problem that the static level monitoring is susceptible to temperature interference and affects the accuracy in slope instability/deformation monitoring.The purpose is to develop a r...Purpose–This study solves the key problem that the static level monitoring is susceptible to temperature interference and affects the accuracy in slope instability/deformation monitoring.The purpose is to develop a reliable temperature compensation method for the system,improve the accuracy of slope stability monitoring and provide support for improving the safety and safety monitoring of engineering spoil slope and other projects.Design/methodology/approach–Combined with theoretical analysis and experimental verification,the temperature compensation method is explored.The working principle of the hydrostatic leveling monitoring system is analyzed and the data processing formula,the temperature error calculation formula and the calculation formula for eliminating the error settlement value are derived.The temperature compensation method is established and verified by the field test of the engineering spoil slope which is disturbed by a debris flow.Findings–The experimental results show that this method can reduce the error of the static level monitoring system by about 40%.The field test shows that the fluctuation of slope settlement monitoring value is reduced after temperature compensation and the monitoring value is consistent with the actual situation,which has certain practicability.Originality/value–The originality of this study is to derive a theoretical formula for quantifying/eliminating temperature errors in static leveling and to establish a practical temperature compensation method.The accuracy of the system is improved,which provides a reference for slope stability monitoring under complex environment(especially railway geotechnical engineering)and promotes the development of precision monitoring technology.展开更多
Sustainable urbanization is essential for developing cities.To ensure the success of planned construction projects,designers must prioritize sustainability by lowering emissions and reducing costs.Tunnel projects are ...Sustainable urbanization is essential for developing cities.To ensure the success of planned construction projects,designers must prioritize sustainability by lowering emissions and reducing costs.Tunnel projects are common worldwide,but disposing of the excavated material presents a significant challenge due to unsuitable geographic conditions.While coastal cities with mountainous terrains have historically used spoil for sea filling,this study offers alternative landside options to promote sustainability.By using a conventional analytical hierarchy process(AHP)method for multi-criteria decision-making(MCDM),the study evaluates land use,sustainability,slope,and drainage lines as constraints for the AHP method.The transportation-related greenhouse gas(GHG)emissions are also considered to reduce environmental damage.Particle swarm optimization is used to determine the minimum transportation distance from the excavation zone to the dumpsite.As a sub-criteria of land use,the seaside is also considered a dumpsite compared with other options on the land side.The spatial analysis results of the case study show that suitable landside sites are available for the Trabzon tunneling project.Although coastal areas in Trabzon have been used for spoil dumping for filling purposes in the past,landside deposition is a viable alternative.The suitability ranks of land and coastal filling options are relatively similar,and selecting the seaside as the dumpsite for the Trabzon tunneling project reduces CO_(2)emissions.By adopting sustainable practices,we can realize a better future for our cities and the environment.展开更多
During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas d...During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas due to the soil depletion.Aiming at recycling the solid waste,the sieved engineering waste slag with local red clay and corn straw biochar was supplied to solve the problem of insufficient nutrients in engineering waste slag and soil.In addition,planting experiments of alfalfa(Medicago sativa L.)and Amorpha fruticosa L.combined with physical and chemical experiments were carried out to prove the feasibility of the novel improved substrate for the reclamation of spoil areas.The results show that the substrate's improvement effect is mainly affected by the soil to slag ratio and the biochar content.The improvement effect of soil matrix in highway spoil area decreases with the increase of the waste slag content,especially when the soil-slag ratio is less than 3,and the promotion of plants is limited.On the contrary,the improvement effect is proportional to the biochar content(3%-8%).But it is noted that the Cu and Pb in the soil will exceed the clean limit corresponding to the Nemero soil pollution index level when the biochar content is 8%.Therefore,it is recommended that the soil-slag ratio should be≥3,and the biochar content should reach 3%-5%.This research provides experimental basis and technical support for utilizing solid waste resources in the reclamation of highway spoil areas.展开更多
A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their in...A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their influence on total nutrient concentrations of coal mine spoil during early phase of plantation establishment. Soil samples were analyzed for total organic carbon （SOC）, Kjeldahl nitrogen （TKN） and phosphorus （TP） at spoil depths of 0-10 and 10-20 cm under 4- and 5-year-old plantations of all species. A significant effect on concentrations of total SOC, TKN and TP were observed due to plantation age, species and soil depth. However, corresponding con- centrations （SOC, TKN and TP） were substantially lower at spoil profile of 10-20 cm. In comparison, plantation ofA. lebbeck showed greater SOC and nutrient concentrations followed by D. strictus, A. procera and T. grandis, respectively. Therefore, present study clearly indicates attributing qualities of plantation towards improving redeveloping soil of mine spoil varied with species.展开更多
Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Te...Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Tectona grandis and Dendrocalamus strictus. The data recorded in the present study were compared with other unplanted coal mine spoil colliery, which was around to the study site and adjoining area of dry tropical forest. Among all the heavy metals, the maximum concentration was found for Fe and minimum for Cd. However, among all four species, total concentrations of these heavy metals were recorded maximally in the plantation plots of T. grandis except for Fe, while minimally in A. lebbeck except for Zn, whereas, the maximum concentration of Fe and Zn was in the plantation plots of D. strictus and A. procera. Statistical analysis revealed significant differences due to species for all the heavy metals except Cu. Among four species, A. lebbeck, A. procera and D. strictus showed more efficient for reducing heavy metal concentrations whereas T. grandis was not more effective to reduce heavy metal concentrations in redeveloping soil of mine spoil.展开更多
With the rapid development of urbanization, a large amount of construction spoil was stockpiled around cities and formed extensive dumps. Construction spoil is one of the main construction and demolition(C&D) wast...With the rapid development of urbanization, a large amount of construction spoil was stockpiled around cities and formed extensive dumps. Construction spoil is one of the main construction and demolition(C&D) waste and municipal solid waste(MSW). Once the construction spoil dump becomes unstable, it will bring great risks to the surrounding residents. A catastrophic dump failure occurred on 20 December 2015 in Guangming New Strict, Shenzhen, China. Approximately 2.51×10^(6) m^(3) of construction waste slid out from the dumpsite, destroying 33 houses and causing total 77 casualties. This paper attempts to analyze the failure probability of the construction spoil dump using Monte Carlo simulation considering the spatial variability of soil properties, and to quantify the dynamic human risk considering the increasing urbanization. Influence of urbanization on the human element at risk is analyzed by referring to multi-temporal remote sensing images. A quantitative human risk assessment model is employed to determine the landslide human risk referring an assessment criteria curve between frequency of number fatalities and number of fatalities(F-N curve). It is found that the societal risk at daytime was 0.078, 0.088, and 1.432 in 2002, 2014, and 2015, respectively. Meanwhile, the societal risk at night was 0.034, 0.037, and 0.611 in 2002, 2014, and 2015, respectively. The quantitative method was benchmarked by the other landfill failure. It implies that the human risk increased with the development of urbanization and its value at daytime was approximately twice as much as at night. The new approach for the human risk assessment provides guidance for modern MSW landfills and highlights the obvious influence of urbanization on the human risk in other areas.展开更多
Long-term studies are essential to learn earthworm community development and soil formation post reclamation.Investigations were undertaken at a former steelworks site at Hallside,near Glasgow,UK,reclaimed in the 1990...Long-term studies are essential to learn earthworm community development and soil formation post reclamation.Investigations were undertaken at a former steelworks site at Hallside,near Glasgow,UK,reclaimed in the 1990s using a mixture of colliery spoil and sewage sludge.The site was largely planted for production of short rotation coppice willow(Salix spp.).Earthworm inoculation formed a part of the restoration process.Minimal monitoring occurred in the interim,but some records of earthworm sampling existed in 2000 and 2005.This study focused on monitoring earthworms and soil properties across the site,drawing comparisons with adjacent unspoiled soil.Results showed that after 22 years,a species-rich community of earthworms(n=16)colonized the site,with endogeic Aporrectodea caliginosa being dominant by number and anecic A.longa by mass.Across the site,earthworm community density and biomass were 208 individuals m^(-2) and 71 g m^(-2),respectively.The Shannon diversity index for earthworms was 1.89,with an evenness of 0.68.The sewage sludge increased the soil organic matter,but the stone content of the colliery spoil prevented digging in some locations.Soil chemistry had no negative effect on earthworms,but the compacted substrate did hinder water infiltration.Earthworms colonized the reclaimed site from adjacent areas,and community structure and density below well-drained,scrub-free willow,birch,and grassland were not significantly different(P>0.05)from those of the adjacent unspoiled areas.The results show that the historical earthworm inoculation was unnecessary and badly timed.Future reclamations of similar sites can learn from this investigation.展开更多
Appalachian USA coal mines have been implicated as major stressors to aquatic life in headwater streams via discharge of total dissolved solids(TDS).This paper summarizes column leaching studies of spoils(n>50)and ...Appalachian USA coal mines have been implicated as major stressors to aquatic life in headwater streams via discharge of total dissolved solids(TDS).This paper summarizes column leaching studies of spoils(n>50)and refuse and TDS effects on local water quality and biotic response.The initial pH of most materials is near-neutral.Initial specific conductance(SC)values range from 500-1,000 to >3,000 μs/cm,but 2/3 of materials drop below 500 ls/cm after several pore volumes of leaching.Studies of mining-influenced streams have found altered aquatic life,relative to natural conditions with no mining influence,at SC ranging from-200 to-700 ls/cm with depressed aquatic life consistently associated with elevated TDS;mechanisms causing such effects are under investigation.We suggest that active mine operations should be modified to place high TDS producing materials in ways that reduce contact with percolating drainage waters.展开更多
An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer bi...An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.展开更多
Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiati...Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiation in different spoil materials.This paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan area.Research shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface layer.Those factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris flows.In contrast,the sandstone spoil is less problematic and causes no major debris flow threats.Based on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.展开更多
An experimental investigation was conducted to identify the characteristics of crack growth in high performance concrete (HPC) subjected to fire, including two parts of work, i.e. crack growth resistance determination...An experimental investigation was conducted to identify the characteristics of crack growth in high performance concrete (HPC) subjected to fire, including two parts of work, i.e. crack growth resistance determinations and cracking observations, using concrete of three strength grades 40 MPa, 70 MPa, and 110 MPa. The crack growth resistance curves (R-curves ) of HPC subjected to high temperatures were determined using notched three-point bend beam specimens of 100 mm×100 mm×300mm. The R-curve (crack growth resistance curve) flattening shows that the crack growth resistance has been significantly reduced by elevated temperature. Concrete with a higher strength grade has a steeper R-curve, with a higher fracture toughness but a shorter critical crack growth. The shorter critical crack growth means that concrete of a higher strength grade has a more brittle behavior. The concrete cracking observations reveal that the consequences of rapid heating are quite different from those of slow heating. For slow heating at a rate of 0.5℃/min, HPC suffered no obvious cracking below 600℃ even if it had a high moisture content. Explosive spalling is an extreme case of the internal cracking driven mainly by vapor pressure. All these results confirmed the vapor pressure mechanism for spading behavior which should be more significant for denser concrete. The crack growth ranges obtained from the R-curve determination results are in good agreement with those measured in the concrete cracking observations.展开更多
The utility of three-dimensional spoiled gradient recalled acquisition in steady state (3D-SPGR) imaging in the cerebral diseases was evaluated and 3D-SPGR after enhancement in depicting contrast enhancement of all le...The utility of three-dimensional spoiled gradient recalled acquisition in steady state (3D-SPGR) imaging in the cerebral diseases was evaluated and 3D-SPGR after enhancement in depicting contrast enhancement of all lesions and 2D-SE T1WI comparatively analyzed. 117 patients were subjected to MRI by a GE 1. 5T MR system. After performance of axial T1WI and T2WI in all patients, MR A (3D-MOTSA) images were acquired in 6 cases (8 lesions) of aneurysms. After enhancement , 3D-SPGR images were obtained in all the remaining patients. Quality parameters (SNR, C and CNR) were calculated on enhanced 2D-SE T1WI and 3D-SPGR images. And a four-point scale was used to measure the signal intensity of the main lesions on both sequences, then statistical analysis of the average score was performed with 't' test. Except for aneurysms, 2D-SE T1WI detected 134 lesions and 3D-SPGR disclosed 147 lesions. It was found that there was no statistically significant difference between the two average scores as determined by the 't' test (t=l. 894, P>0. 05). The enhancement degree of the main lesion was equivalent on 3D-SPGR and 2D-SE T1WI. Quality parameters (SNR, C and CNR) on 2D-SE T1WI were much larger than that of 3D-SPGR, increasing by an average of 57 %, 20 % and 97 % respectively. 3D-SPGR imaging with MPR could clearly depict vascularity related to neoplasms in 20 cases and demonstrate shifted, deformed and blocked vessels involved by tumors. Six cases of large aneurysms (8 lesions) were visualized more clearly on 3D-SPGR than MRA (3D-MOTSA): 3D-SPGR could display aneurysm necks and differentiate thrombosed portion from the patent lumen, and disclose relationship of aneurysm to surrounding structures. It was concluded that enhanced 3D-SPGR played an important role in the depiction of the cerebral lesions and was superior to 2D-SE T1WI in many aspects.展开更多
The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to ab...The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to abbreviate ten physical and mechanical parametersto three dimensionless groups, and then the similarity criterion and coefficient ofthe experiment were determined and calculated based on particle size distribution curve.The similarity model was designed and constructed to represent the process of the minespoil pile.The profile of the final model shows that the small sized particles mainly composethe upper zone of the mine spoil pile, while the bottom of the pile is dominated bybigger sized particles, and the intermediate section presents a zigzag stripe cross-beddingstructure which is composed by small-medium scale particles and medium-large scaleparticles.Each stripe has two critical angles: one is the angle in which gangue particlescan maintain their stability condition, with approximate range from 24° to 26°; and theother is the angle in which particles can stop gliding downwards, approximately varyingfrom 34° to 36°.展开更多
Lipovtsy coal field mine №4 processed north-western reserves of Lipovtsy field in Primorski Krai (Russia). In 1997, the mine was declared unprofitable and was abandoned by natural flooding with no arrangement of mine...Lipovtsy coal field mine №4 processed north-western reserves of Lipovtsy field in Primorski Krai (Russia). In 1997, the mine was declared unprofitable and was abandoned by natural flooding with no arrangement of mine water discharge and in 2005 it was fully flooded. The main sources of pollution in the studied area are spoil heaps (mine wastes), underspoil filtering waters and mine waters which are being discharged on the surface after finishing of “hydraulic funnel” artificial support. The study of technogenic landscape of abandoned mine industrial area showed that its morphologic form is dominated by spoil heaps. Soils located near mine waste body differ from benchmark soils by chemical properties and size distribution. The influence of active hydrochemical mine and drainage water flows is the reason of the above-mentioned variation in soil properties. Results showed that, there exist a high correlation ratios between chemical composition of mine waters and water extracts from soil: Between the alkalinity of mine waters and electrical conductivity of soil water extracts (r = 0.73), between mine water iron content and pH of soil water extract (r = −0.56), between the solid residue of mine waters and electrical conductivity of soil water extracts (r = 0.72), between the mine waters calcium content and electrical conductivity of soil water extracts (r = −0.75), between the alkalinity of mine waters and silicon dioxide content of soil water extracts (r = 0.61), between the mineralization of mine waters and chrome content of soil water extracts (r = 0.73).展开更多
Open-cast lignite mining operations result in a loss of soil quality. Soils associated with coal mining are usually characterised by poor physical and chemical parameters. Low pH and heavy metal toxicity are of the ma...Open-cast lignite mining operations result in a loss of soil quality. Soils associated with coal mining are usually characterised by poor physical and chemical parameters. Low pH and heavy metal toxicity are of the main concerns. The lignite and pyrite content of the dump materials of the Lusatian open-cast mining district in Eastern Germany resulted in high acidification potential and low organic matter content of soils. These extreme conditions require considerable amounts of alkaline materials like compost to enable revegetation. This study was carried out to evaluate the effect of different application rates of wood compost on soil physico-chemical properties in two representative soil substrates (tertiary and quaternary) and on some plant growth parameters. Soil in each site was mixed with wood compost and sown with a grass mixture. The data of both studied soils showed an improvement in physical properties such as water holding capacity and bulk density in soil ameliorated with compost. Most soil chemical properties were increased significantly with the increase of compost application rates, particularly organic matter content, total nitrogen and cation exchange capacity. Compared to the control treatment in each site, the treated soil with compost showed a significant increase in grass biomass (fresh and dry matter yield). The results of these experiments revealed that addition of wood compost had significant positive effects on the soil physical and chemical properties, which affected the response of plant growth and can facilitate the revegetation of substrates contaminated with coal spoil.展开更多
Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called ...Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called coal spoil. Coal spoil can impose environmental threat if not treated carefully. In contrast, it can also be converted to value added product. In the present work, coal spoils collected from Barapukuria coal mine drainage water were investigated to determine the quality of the samples by physico-chemical analysis (proximate and ultimate analysis) as well as by heating value determination. 50% of carbon was detected in the samples after elemental analysis, with sulfur content less than 0.4%. Calorific value around 9300 btu/lb was obtained for the coal spoil. Moreover, moisture content, ash, volatile matter content and fixed carbon also provided fruitful information regarding the quality and economic prospect of the samples in comparison to the quality of Barapukuria coal.展开更多
In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Ho...In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Hong Kong businessman, explains his parenting approach in his book That＇s Why They Go to Peking University, which has stirred controversy over his parenting methods since its publication release in June.展开更多
文摘Reclamation and revegetation of a coal mine spoils with various revegetation models utilizing the mycorrhizal technology were studied. The models with different combination of plant species were designed to test the hypothesis of speedy revegetation. Root colonization and spore density of arbuscular mycorrhizae (AM) were lowest in plants seeded directly on slopes of the overburden (coal mine dump). At flat surfaces, the mycorrhizal colonization in plant species was higher than that observed at slopes. In other revegetation models, i.e., tree monoculture, tree monoculture + crop species (agroforestry), and two strata plantations (combination of different plant species), maximum AM colonization was recorded for tree species grown along with crop species. This was followed by two strata plantations and tree monoculture. In two strata plantations three categories of AM associations were recognized: 1) every plant in the combination, possessed high mycorrhizal association, 2) only one plant in the combination possessed high mycorrhizal association, and 3) none of the plants in the combination possessed high mycorrhizal association. Azadirachta indica, Pongamia pinnata, Leucaena leucocephala and Acacia catechu were most effective in catching mycorrhizae, and can be used as the effective tool in rehabilitation of the degraded ecosystems.
基金financially supported by the National Natural Science Foundation of China(Nos.41120124003 and 41372251)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130145120014)+1 种基金the Natural Science Foundation of Hubei Province,China(No.2013CFB41)the Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(No.SKLGP2012K022)
文摘The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.
基金funded by the Scientific Research Project of China Academy of Railway Sciences Group Co.,Ltd(No.2024YJ332 and No.2024QT005)Scientific Research Special Project of China State Railway Group Co.,Ltd(No.TICSTR-2024-Ⅳ-007).
文摘Purpose–This study solves the key problem that the static level monitoring is susceptible to temperature interference and affects the accuracy in slope instability/deformation monitoring.The purpose is to develop a reliable temperature compensation method for the system,improve the accuracy of slope stability monitoring and provide support for improving the safety and safety monitoring of engineering spoil slope and other projects.Design/methodology/approach–Combined with theoretical analysis and experimental verification,the temperature compensation method is explored.The working principle of the hydrostatic leveling monitoring system is analyzed and the data processing formula,the temperature error calculation formula and the calculation formula for eliminating the error settlement value are derived.The temperature compensation method is established and verified by the field test of the engineering spoil slope which is disturbed by a debris flow.Findings–The experimental results show that this method can reduce the error of the static level monitoring system by about 40%.The field test shows that the fluctuation of slope settlement monitoring value is reduced after temperature compensation and the monitoring value is consistent with the actual situation,which has certain practicability.Originality/value–The originality of this study is to derive a theoretical formula for quantifying/eliminating temperature errors in static leveling and to establish a practical temperature compensation method.The accuracy of the system is improved,which provides a reference for slope stability monitoring under complex environment(especially railway geotechnical engineering)and promotes the development of precision monitoring technology.
文摘Sustainable urbanization is essential for developing cities.To ensure the success of planned construction projects,designers must prioritize sustainability by lowering emissions and reducing costs.Tunnel projects are common worldwide,but disposing of the excavated material presents a significant challenge due to unsuitable geographic conditions.While coastal cities with mountainous terrains have historically used spoil for sea filling,this study offers alternative landside options to promote sustainability.By using a conventional analytical hierarchy process(AHP)method for multi-criteria decision-making(MCDM),the study evaluates land use,sustainability,slope,and drainage lines as constraints for the AHP method.The transportation-related greenhouse gas(GHG)emissions are also considered to reduce environmental damage.Particle swarm optimization is used to determine the minimum transportation distance from the excavation zone to the dumpsite.As a sub-criteria of land use,the seaside is also considered a dumpsite compared with other options on the land side.The spatial analysis results of the case study show that suitable landside sites are available for the Trabzon tunneling project.Although coastal areas in Trabzon have been used for spoil dumping for filling purposes in the past,landside deposition is a viable alternative.The suitability ranks of land and coastal filling options are relatively similar,and selecting the seaside as the dumpsite for the Trabzon tunneling project reduces CO_(2)emissions.By adopting sustainable practices,we can realize a better future for our cities and the environment.
基金supported by the National Natural Science Foundation of China(Grant No.52078034).
文摘During the highway construction,a large number of spoil areas will be generated while a large amount of waste slag and soil could not be rationally utilized.Besides,the vegetation recovery is slow in the spoil areas due to the soil depletion.Aiming at recycling the solid waste,the sieved engineering waste slag with local red clay and corn straw biochar was supplied to solve the problem of insufficient nutrients in engineering waste slag and soil.In addition,planting experiments of alfalfa(Medicago sativa L.)and Amorpha fruticosa L.combined with physical and chemical experiments were carried out to prove the feasibility of the novel improved substrate for the reclamation of spoil areas.The results show that the substrate's improvement effect is mainly affected by the soil to slag ratio and the biochar content.The improvement effect of soil matrix in highway spoil area decreases with the increase of the waste slag content,especially when the soil-slag ratio is less than 3,and the promotion of plants is limited.On the contrary,the improvement effect is proportional to the biochar content(3%-8%).But it is noted that the Cu and Pb in the soil will exceed the clean limit corresponding to the Nemero soil pollution index level when the biochar content is 8%.Therefore,it is recommended that the soil-slag ratio should be≥3,and the biochar content should reach 3%-5%.This research provides experimental basis and technical support for utilizing solid waste resources in the reclamation of highway spoil areas.
文摘A study was conducted on high-density young plantations of three native trees （Albizia lebbeck, Albizia. procera and Tectona grandis） and one native woody grass species （Dendrocalamus strictus） to examine their influence on total nutrient concentrations of coal mine spoil during early phase of plantation establishment. Soil samples were analyzed for total organic carbon （SOC）, Kjeldahl nitrogen （TKN） and phosphorus （TP） at spoil depths of 0-10 and 10-20 cm under 4- and 5-year-old plantations of all species. A significant effect on concentrations of total SOC, TKN and TP were observed due to plantation age, species and soil depth. However, corresponding con- centrations （SOC, TKN and TP） were substantially lower at spoil profile of 10-20 cm. In comparison, plantation ofA. lebbeck showed greater SOC and nutrient concentrations followed by D. strictus, A. procera and T. grandis, respectively. Therefore, present study clearly indicates attributing qualities of plantation towards improving redeveloping soil of mine spoil varied with species.
文摘Total concentration of heavy metals(Cd, Cr, Cu, Fe, Pb, Ni, Mn and Zn) was estimated in the redeveloping soil of mine spoil under 5 yr old plantations of four woody species namely: Albizia lebbeck, Albizia procera, Tectona grandis and Dendrocalamus strictus. The data recorded in the present study were compared with other unplanted coal mine spoil colliery, which was around to the study site and adjoining area of dry tropical forest. Among all the heavy metals, the maximum concentration was found for Fe and minimum for Cd. However, among all four species, total concentrations of these heavy metals were recorded maximally in the plantation plots of T. grandis except for Fe, while minimally in A. lebbeck except for Zn, whereas, the maximum concentration of Fe and Zn was in the plantation plots of D. strictus and A. procera. Statistical analysis revealed significant differences due to species for all the heavy metals except Cu. Among four species, A. lebbeck, A. procera and D. strictus showed more efficient for reducing heavy metal concentrations whereas T. grandis was not more effective to reduce heavy metal concentrations in redeveloping soil of mine spoil.
基金This study was funded by the National Key R&D Program of China(Grant Nos.2019YFC1806001,2018YFC1802301)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.41907243)the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.UGC/FDS25/E11/17)。
文摘With the rapid development of urbanization, a large amount of construction spoil was stockpiled around cities and formed extensive dumps. Construction spoil is one of the main construction and demolition(C&D) waste and municipal solid waste(MSW). Once the construction spoil dump becomes unstable, it will bring great risks to the surrounding residents. A catastrophic dump failure occurred on 20 December 2015 in Guangming New Strict, Shenzhen, China. Approximately 2.51×10^(6) m^(3) of construction waste slid out from the dumpsite, destroying 33 houses and causing total 77 casualties. This paper attempts to analyze the failure probability of the construction spoil dump using Monte Carlo simulation considering the spatial variability of soil properties, and to quantify the dynamic human risk considering the increasing urbanization. Influence of urbanization on the human element at risk is analyzed by referring to multi-temporal remote sensing images. A quantitative human risk assessment model is employed to determine the landslide human risk referring an assessment criteria curve between frequency of number fatalities and number of fatalities(F-N curve). It is found that the societal risk at daytime was 0.078, 0.088, and 1.432 in 2002, 2014, and 2015, respectively. Meanwhile, the societal risk at night was 0.034, 0.037, and 0.611 in 2002, 2014, and 2015, respectively. The quantitative method was benchmarked by the other landfill failure. It implies that the human risk increased with the development of urbanization and its value at daytime was approximately twice as much as at night. The new approach for the human risk assessment provides guidance for modern MSW landfills and highlights the obvious influence of urbanization on the human risk in other areas.
基金This work was financially supported by the Legacy Initiative of the British Land Reclamation Society(No.3290).
文摘Long-term studies are essential to learn earthworm community development and soil formation post reclamation.Investigations were undertaken at a former steelworks site at Hallside,near Glasgow,UK,reclaimed in the 1990s using a mixture of colliery spoil and sewage sludge.The site was largely planted for production of short rotation coppice willow(Salix spp.).Earthworm inoculation formed a part of the restoration process.Minimal monitoring occurred in the interim,but some records of earthworm sampling existed in 2000 and 2005.This study focused on monitoring earthworms and soil properties across the site,drawing comparisons with adjacent unspoiled soil.Results showed that after 22 years,a species-rich community of earthworms(n=16)colonized the site,with endogeic Aporrectodea caliginosa being dominant by number and anecic A.longa by mass.Across the site,earthworm community density and biomass were 208 individuals m^(-2) and 71 g m^(-2),respectively.The Shannon diversity index for earthworms was 1.89,with an evenness of 0.68.The sewage sludge increased the soil organic matter,but the stone content of the colliery spoil prevented digging in some locations.Soil chemistry had no negative effect on earthworms,but the compacted substrate did hinder water infiltration.Earthworms colonized the reclaimed site from adjacent areas,and community structure and density below well-drained,scrub-free willow,birch,and grassland were not significantly different(P>0.05)from those of the adjacent unspoiled areas.The results show that the historical earthworm inoculation was unnecessary and badly timed.Future reclamations of similar sites can learn from this investigation.
基金supported by a wide array of sponsors including the Powell River Project and the USDI Office of Surface Mining Applied Science ProgramAportion of the work reported was also sponsored by the Appalachian Research Initiative for Environmental Science(ARIES).ARIES is an industrial affiliates program at Virginia Tech,supported by members that include companies in the energy sector.
文摘Appalachian USA coal mines have been implicated as major stressors to aquatic life in headwater streams via discharge of total dissolved solids(TDS).This paper summarizes column leaching studies of spoils(n>50)and refuse and TDS effects on local water quality and biotic response.The initial pH of most materials is near-neutral.Initial specific conductance(SC)values range from 500-1,000 to >3,000 μs/cm,but 2/3 of materials drop below 500 ls/cm after several pore volumes of leaching.Studies of mining-influenced streams have found altered aquatic life,relative to natural conditions with no mining influence,at SC ranging from-200 to-700 ls/cm with depressed aquatic life consistently associated with elevated TDS;mechanisms causing such effects are under investigation.We suggest that active mine operations should be modified to place high TDS producing materials in ways that reduce contact with percolating drainage waters.
基金NSFC (National natural science foundation of China) for funding(Grant No. 30870467) this paper
文摘An experiment was performed to study the influence of polymer binders on the physical properties,and stability against a simulated rainfall,of a slope consisting of engineering spoil.Results showed that low polymer binder concentrations(≤500g/m3) could enhance the air permeability and moisture-retaining capacity of the engineering spoil;however,adding more polymer binder made the hardness of the engineering spoil increase and then decline.With the increase of polymer binder concentrations,the surface(0-5cm) permeability of the engineering spoil decreased but the permeability of the lower layers(5-10cm) increased.Polymer binders might reduce runoff and sediment,but the effect becomes weaker with the increase of rainfall.The results of this study have significance for engineering practices.Further experiments are needed to study the effects of binders under other conditions,such as natural rainfall,different slopes,different rock types,different degrees and spoil weathering and different added material,and the chemical interaction between soil and polymer binders.
基金funded by the Ministry of Science and Technology of the People’s Republic of China (Grant No.2011BAK12B02)the Science and Technology Department of Sichuan Province(Grant No.2011SZ0190)
文摘Large spoil tips from reconstruction works as a result of the Wenchuan Earthquake in China are new debris flow hazards to the human society.However,there is a lack of detailed comparative study on debris flow initiation in different spoil materials.This paper describes a series of tests and analyses on debris flow characteristics(initiation,scale and mechanism) at six sites with limestone and sandstone materials near the Dujiangyan area.Research shows the limestone spoil contains debris flow prone clay content with high concentration of montmorillonite(highly expandable).In addition,limestone spoil is of such a low permeability that water mainly concentrates in the upper surface layer.Those factors make it easy for the increase of pore water pressure,decline of internal friction and conhesion force,leading to the occurence of large debris flows.In contrast,the sandstone spoil is less problematic and causes no major debris flow threats.Based on our research on the mechanism,the"stereometric drainage"method is sucessfully applied to control limestone spoil debris flows.
基金The authors gratefully acknowledge the financial support of both the National Natural Science Foundation of China(project No.50108001)the Pandeng Foundation Project of Beijing Jiao Tong University.
文摘An experimental investigation was conducted to identify the characteristics of crack growth in high performance concrete (HPC) subjected to fire, including two parts of work, i.e. crack growth resistance determinations and cracking observations, using concrete of three strength grades 40 MPa, 70 MPa, and 110 MPa. The crack growth resistance curves (R-curves ) of HPC subjected to high temperatures were determined using notched three-point bend beam specimens of 100 mm×100 mm×300mm. The R-curve (crack growth resistance curve) flattening shows that the crack growth resistance has been significantly reduced by elevated temperature. Concrete with a higher strength grade has a steeper R-curve, with a higher fracture toughness but a shorter critical crack growth. The shorter critical crack growth means that concrete of a higher strength grade has a more brittle behavior. The concrete cracking observations reveal that the consequences of rapid heating are quite different from those of slow heating. For slow heating at a rate of 0.5℃/min, HPC suffered no obvious cracking below 600℃ even if it had a high moisture content. Explosive spalling is an extreme case of the internal cracking driven mainly by vapor pressure. All these results confirmed the vapor pressure mechanism for spading behavior which should be more significant for denser concrete. The crack growth ranges obtained from the R-curve determination results are in good agreement with those measured in the concrete cracking observations.
文摘The utility of three-dimensional spoiled gradient recalled acquisition in steady state (3D-SPGR) imaging in the cerebral diseases was evaluated and 3D-SPGR after enhancement in depicting contrast enhancement of all lesions and 2D-SE T1WI comparatively analyzed. 117 patients were subjected to MRI by a GE 1. 5T MR system. After performance of axial T1WI and T2WI in all patients, MR A (3D-MOTSA) images were acquired in 6 cases (8 lesions) of aneurysms. After enhancement , 3D-SPGR images were obtained in all the remaining patients. Quality parameters (SNR, C and CNR) were calculated on enhanced 2D-SE T1WI and 3D-SPGR images. And a four-point scale was used to measure the signal intensity of the main lesions on both sequences, then statistical analysis of the average score was performed with 't' test. Except for aneurysms, 2D-SE T1WI detected 134 lesions and 3D-SPGR disclosed 147 lesions. It was found that there was no statistically significant difference between the two average scores as determined by the 't' test (t=l. 894, P>0. 05). The enhancement degree of the main lesion was equivalent on 3D-SPGR and 2D-SE T1WI. Quality parameters (SNR, C and CNR) on 2D-SE T1WI were much larger than that of 3D-SPGR, increasing by an average of 57 %, 20 % and 97 % respectively. 3D-SPGR imaging with MPR could clearly depict vascularity related to neoplasms in 20 cases and demonstrate shifted, deformed and blocked vessels involved by tumors. Six cases of large aneurysms (8 lesions) were visualized more clearly on 3D-SPGR than MRA (3D-MOTSA): 3D-SPGR could display aneurysm necks and differentiate thrombosed portion from the patent lumen, and disclose relationship of aneurysm to surrounding structures. It was concluded that enhanced 3D-SPGR played an important role in the depiction of the cerebral lesions and was superior to 2D-SE T1WI in many aspects.
基金Supported by the National Natural Science Foundation of China(50874102,50974070)
文摘The aim of the experiment is to analyze and view the distribution of gangue withdifferent particle sizes in mine spoil pile cross section.According to the Dimensionalmethod,'Pi'theorem was employed first to abbreviate ten physical and mechanical parametersto three dimensionless groups, and then the similarity criterion and coefficient ofthe experiment were determined and calculated based on particle size distribution curve.The similarity model was designed and constructed to represent the process of the minespoil pile.The profile of the final model shows that the small sized particles mainly composethe upper zone of the mine spoil pile, while the bottom of the pile is dominated bybigger sized particles, and the intermediate section presents a zigzag stripe cross-beddingstructure which is composed by small-medium scale particles and medium-large scaleparticles.Each stripe has two critical angles: one is the angle in which gangue particlescan maintain their stability condition, with approximate range from 24° to 26°; and theother is the angle in which particles can stop gliding downwards, approximately varyingfrom 34° to 36°.
文摘Lipovtsy coal field mine №4 processed north-western reserves of Lipovtsy field in Primorski Krai (Russia). In 1997, the mine was declared unprofitable and was abandoned by natural flooding with no arrangement of mine water discharge and in 2005 it was fully flooded. The main sources of pollution in the studied area are spoil heaps (mine wastes), underspoil filtering waters and mine waters which are being discharged on the surface after finishing of “hydraulic funnel” artificial support. The study of technogenic landscape of abandoned mine industrial area showed that its morphologic form is dominated by spoil heaps. Soils located near mine waste body differ from benchmark soils by chemical properties and size distribution. The influence of active hydrochemical mine and drainage water flows is the reason of the above-mentioned variation in soil properties. Results showed that, there exist a high correlation ratios between chemical composition of mine waters and water extracts from soil: Between the alkalinity of mine waters and electrical conductivity of soil water extracts (r = 0.73), between mine water iron content and pH of soil water extract (r = −0.56), between the solid residue of mine waters and electrical conductivity of soil water extracts (r = 0.72), between the mine waters calcium content and electrical conductivity of soil water extracts (r = −0.75), between the alkalinity of mine waters and silicon dioxide content of soil water extracts (r = 0.61), between the mineralization of mine waters and chrome content of soil water extracts (r = 0.73).
文摘Open-cast lignite mining operations result in a loss of soil quality. Soils associated with coal mining are usually characterised by poor physical and chemical parameters. Low pH and heavy metal toxicity are of the main concerns. The lignite and pyrite content of the dump materials of the Lusatian open-cast mining district in Eastern Germany resulted in high acidification potential and low organic matter content of soils. These extreme conditions require considerable amounts of alkaline materials like compost to enable revegetation. This study was carried out to evaluate the effect of different application rates of wood compost on soil physico-chemical properties in two representative soil substrates (tertiary and quaternary) and on some plant growth parameters. Soil in each site was mixed with wood compost and sown with a grass mixture. The data of both studied soils showed an improvement in physical properties such as water holding capacity and bulk density in soil ameliorated with compost. Most soil chemical properties were increased significantly with the increase of compost application rates, particularly organic matter content, total nitrogen and cation exchange capacity. Compared to the control treatment in each site, the treated soil with compost showed a significant increase in grass biomass (fresh and dry matter yield). The results of these experiments revealed that addition of wood compost had significant positive effects on the soil physical and chemical properties, which affected the response of plant growth and can facilitate the revegetation of substrates contaminated with coal spoil.
文摘Barapukuria Coal Mine situated in the district Dinajpur. Bangladesh is playing an important role in the economy of this country by the mining of top quality coal. With coal mining, mine waste is also generated called coal spoil. Coal spoil can impose environmental threat if not treated carefully. In contrast, it can also be converted to value added product. In the present work, coal spoils collected from Barapukuria coal mine drainage water were investigated to determine the quality of the samples by physico-chemical analysis (proximate and ultimate analysis) as well as by heating value determination. 50% of carbon was detected in the samples after elemental analysis, with sulfur content less than 0.4%. Calorific value around 9300 btu/lb was obtained for the coal spoil. Moreover, moisture content, ash, volatile matter content and fixed carbon also provided fruitful information regarding the quality and economic prospect of the samples in comparison to the quality of Barapukuria coal.
文摘In current society where most parents praise children, a father who claims that frequent criticisms and beatings help make his children suc- cessful, has captured the public＇s attention. Xiao Baiyou, a 47-year-old Hong Kong businessman, explains his parenting approach in his book That＇s Why They Go to Peking University, which has stirred controversy over his parenting methods since its publication release in June.
