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Land remediation and ecological restoration of mined land
... Soil pollution by heavy metals has caused significant menace to food safety and human health. In 1999, the area of agricultural land contaminated by Pb, Zn and Cd was near 20 million hectare, which accounted for approximately one fifth of total cultivated land in China (Wong and Luo, 2003). Statistics showed that by 2001, the destructed mine land area arrived at 2.88 million hectare in China, which increased by 46,700 hectare annually (Wong and Luo, 2003). ...
... In 1999, the area of agricultural land contaminated by Pb, Zn and Cd was near 20 million hectare, which accounted for approximately one fifth of total cultivated land in China (Wong and Luo, 2003). Statistics showed that by 2001, the destructed mine land area arrived at 2.88 million hectare in China, which increased by 46,700 hectare annually (Wong and Luo, 2003). More seriously, wherever in highly polluted mine waste sites, or less polluted agricultural soils, soil pollution often shows complex combined contamination by multiple heavy metals, thus rendering of great difficulties for the disposal and remediation of heavy metal contaminated soils . ...
A field investigation and a pot experiment were conducted to study the Zn and Cd accumulation in Picris divaricata Vant. Under natural conditions, the average Zn and Cd concentrations in shoot of P. divaricata were 5911 and 246 µg g−1 (DW), with the maxima of 18,339 and 585 µg g−1, respectively. Grown on a mixed soil for three months, P. divaricata accumulated up to 15,183 g g−1 Zn and 364 µg g−1 Cd in shoot with translocation factors of Zn and Cd all larger than one. Thus, P. divaricata could be identified as a new Zn and Cd hyperaccumulator found in China.
... In general, minesoil is characterized by the elevated heavy metal concentrations, defi ciency of major nutrients, poor physical structure, extreme acidity and/or salinity, drought, and other stressful factors (Li, 2006;Shu et al. 2005;Wong and Luo, 2003;Yang et al. 2003). Heavy metal pollution of minesoil is a widely documented problem Lei et al. 2005;Xie et al. 2005) but has been largely overlooked in China because they are usually remote to the densely populated urban areas. ...
... Thus simple reclamation for agriculture use is of high risk unless suffi cient treatments, e.g. separation layer, cover of guest soil over 50-cm deep (Wong and Luo, 2003), or substantial substrate amendments (Li, 2006), are in place before planting. ...
Heavy metal contamination of minesoils is a widespread problem in China. In Pingle manganese mineland in Guangxi (south China), heavy metal concentrations in soils and dominant plants were determined, and soil contamination was assessed with pollution index (Pi) and index of geoaccumulation (I-geo). Pi showed the minesoil was heavily polluted by Cd and slightly polluted by Cr. I-geo showed a severer pollution for all metals (except for Mn) than Pi because I-geo tended to overestimate the real pollution effect of minesoil. Fresh tailings dam had both the highest Pi and I-geo among the four sites indicating a high metal contamination. All the "bio-available" fractions of the studied metals were below 5% of the totals. Dominant plants tended to accumulate higher Cd and Cr, and showed higher Mn translocation to aboveground parts. Besides the agricultural reclamation, more diverse restoration goals with lower environmental risks should be considered for the Mn mine wastelands in South China.
... The pH value of soil in the study area is lower than that of natural grazing grassland, but the change difference is not significant, indicating that mining activities in the mining area will have a certain impact on the organic matter that improves the availability of soil nutrients, and the phosphate, nitrogen and potassium elements that are better absorbed and grown by plants. Huang et al. found that the soil nutrients around the mining area were only 30% of the soil covered by normal vegetation, and mining activities had seriously affected the normal growth of plants around the mining area [11]. Zhao et al. believed that slope, slope direction, elevation and topographic moisture index were the main topographic factors affecting soil nutrient pattern characteristics in Shengli Coalfield, and soil disturbance caused by mining activities was an important reason for the low nutrient content [12]. ...
To study the effects of the open-pit mining area and surrounding area on soil nutrients, we take the Inner Mongolia Typical open-pit metal mine in the desert steppe. Soil nutrient contents were analyzed by collecting soil samples at different distances from the mining area. The results showed that referring to the soil nutrient grading standards, total phosphorus, available potassium and available phosphorus content of soil were at a relatively low level in the study area. The contents of available phosphorus, available potassium, organic matter, and alkali-hydrolyzed nitrogen increased significantly with the increase of distance from the mining center. The results indicated that open-pit mining could obviously affect the accumulation of organic matter and available nutrients in the soil, but had no obvious effect on the pH value of the soil. The content of main nutrients in the soil 1 km-2 km inside and around the mining area was significantly lower than that of CK (natural grassland). When the soil nutrients in the area 5 km away from the mining center were basically similar to the control area, it indicated that the soil nutrients in the area 5 km away from the mining center were basically not affected by mining activities.
... Their success is due to the symbiosis that they establish with the root nodules bacteria, commonly called rhizobia, which makes legumes autotrophic to the nitrogen fixed from the atmosphere (Shamseldin et al., 2005). They improve soil fertility and are therefore widely used in areas in course of desertification, or affected by salinity, drought, and high temperatures (Surange et al., 1997;Wong & Luo, 2003). They are widely used for the rehabilitation of degraded soils and production of both fodder and woody biomass. ...
... For example, Wei et al. found that the soil water content in mining subsidence areas is generally smaller than that in nonsubsidence areas [5]. Huang and Luo found that the contents of organic matter, nitrogen, and phosphorus in the mining area soil were only 20%∼30%, compared with those in the vegetation-covered soil [6]. A good many research results show that the structure, fertility, pH value, and other aspects of the reconstructed soil in the mining area are greatly different from those in the ordinary farmland, and the soil productivity is difficult to reach the same level as the previous or cultivated soil [7][8][9]. ...
Aiming at the problem of soil improvement for mining wasteland reclamation, this article takes the coal mining subsidence reclamation area of a coal mine in the east of China as the research object. Compost improvement and green manure improvement experiments were carried out to study the impact of different biomass improvement methods on the quality of reclaimed soil. 10 soil physical and chemical indicators including water content, total nitrogen, ammonia nitrogen, nitrate nitrogen, available phosphorus, available potassium, total phosphorus, organic matter, pH, and conductivity were selected to evaluate the effect of soil improvement. After 5 months of soil improvement, the results showed that planting alfalfa and Mexican corn in the reclaimed area can increase soil available phosphorus, available potassium, total phosphorus, and organic matter content. Cattail, a common aquatic plant in the coal mining subsidence area in the east, is used to make organic compost. When the compost is applied to reclaimed soil, the content of available phosphorus, available potassium, and total phosphorus in the soil can be significantly increased. Using white vanilla clover as green manure for reclaiming soil can significantly increase the content of nitrate nitrogen, available phosphorus, available potassium, and total phosphorus in the soil. Biomass improvement technology can improve the fertility level of coal mine reclamation soil in a short time. It is conducive to promoting the restoration of soil fertility of mining wasteland and realizing the sustainable development and utilization of plant resources and land resources.
... The exploitation of mineral resources is necessary for economic development, but it has also caused severe environmental pollution in mining areas, resulting in reduced crop yields, concentrations of heavy metals in agricultural products exceeding food safety standards (MOH 2005) and threats to human health via the food chain (Dudka and Adriano 1997;Wong and Luo 2003). Safe crop production on the large areas of farmland polluted by mining activities or other anthropogenic activities has become a major societal concern. ...
... The exploitation of mineral resources is necessary for economic development, but it has also caused severe environmental pollution in mining areas, resulting in reduced crop yields, concentrations of heavy metals in agricultural products exceeding food safety standards (MOH 2005) and threats to human health via the food chain (Dudka and Adriano 1997;Wong and Luo 2003). Safe crop production on the large areas of farmland polluted by mining activities or other anthropogenic activities has become a major societal concern. ...
Economic and highly effective methods of in situ remediation of Cd and As polluted farmland in mining areas are urgently needed. Pot experiments with Brassica chinensis L. were carried out to determine the effects of three soil amendments [a novel iron-silicon material (ISM), a synthetic zeolite (SZ) and an alkaline clay (AC)] on vegetable uptake of As and Cd. SEM–EDS and XRD analyses were used to investigate the remediation mechanisms involved. Amendment with ISM significantly reduced the concentrations of As and Cd in edible parts of B. chinensis (by 84–94 % and 38–87 %, respectively), to levels that met food safety regulations and was much lower than those achieved by SZ and AC. ISM also significantly increased fresh biomass by 169–1412 % and 436–731 % in two consecutive growing seasons, while SZ and AC did not significantly affect vegetable growth. Correlation analysis suggested that it was the mitigating effects of ISM on soil acidity and on As and Cd toxicity, rather than nutrient amelioration, that contributed to the improvement in plant growth. SEM–EDS analysis showed that ISM contained far more Ca, Fe and Mn than did SZ or AC, and XRD analysis showed that in the ISM these elements were primarily in the form of silicates, oxides and phosphates that had high capacities for chemisorption of metal(loid)s. After incubation with solutions containing 800 mg L⁻¹ AsO4²⁻ or Cd²⁺, ISM bound distinctly higher levels of As (6.18 % in relative mass percent by EDS analysis) and Cd (7.21 % in relative mass percent by EDS analysis) compared to SZ and AC. XRD analysis also showed that ISM facilitated the precipitation of Cd²⁺ as silicates, phosphates and hydroxides, and that arsenate combined with Fe, Al, Ca and Mg to form insoluble arsenate compounds. These precipitation mechanisms were much more active in ISM than in SZ or AC. Due to the greater pH elevation caused by the abundant calcium silicate, chemisorption and precipitation mechanisms in ISM treatments could be further enhanced. That heavy metal(loid)s fixation mechanisms of ISM ensure the remediation more irreversible and more resilient to environmental changes. With appropriate application rate and proper nutrients supplement, the readily available and economic ISM is a very promising amendment for safe crop production on multi-metal(loids) polluted soils.
... In southern China paddy field soil has become an important and unique agro-ecosystem, because of its large area, acid soil properties and flooded cultivation (Li et al., 2005). However, these paddy soils have been suffering from trace metal pollution (Wong and Luo, 2003). Unfortunately, because of little information on risk assessments, less obvious inhibition for crop growth, and a shortage of arable soil resources, some of these soils have been continuously and intensively cultivated (Zheng et al., 2001). ...
Physicochemical properties, total and DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Zn, Pb and Cd contents, microbial biomass carbon (C) content and the organic C mineralization rate of the soils in a long-term trace metal-contaminated paddy region of Guangdong, China were determined to assess the sensitivity of microbial indices to moderately metal-contaminated paddy soils. The mean contents of total Cu, Zn, Pb and Cd were 251, 250, 171, and 2.4 mg kg -1 respectively. DTPA-extractable metals were correlated positively and significantly with total metals, CEC, and organic C (except for DTPA-extractable Cd), while they were negatively and highly significantly correlated with pH, total Fe and Mn. Metal stress resulted in relatively low ratios of microbial biomass C to organic C and in remarkable inhibition of the microbial metabolic quotient and C mineralization rate, which eventually led to increases in soil organic C and C/N. Moreover, microbial respiratory activity showed a stronger correlation to DTPA-extractable metals than to total metal content. Likewise, in the acid paddy soils some "linked" microbial activity indices, such as metabolic quotient and ratios of basal respiration to organic C, especially during initial incubation, were found to be more sensitive indicators of soil trace metal contamination than microbial biomass C or basal respiration alone.
... With the development of lead-zinc mineral resources, heavy metals were released and transferred into the ecological environment [1], which caused serious environmental problems. The contents of organic matter, nitrogen and phosphorus in the soil around the mine tailing area were reduced to levels that were 20% -30% of those found in normal conditions [2,3]. As a result, it was urgent to apply ecological remediation methods in the lead-zinc mining area. ...
The tailing ponds of lead-zinc mines are artificial environment pollution sources, and also important dangerous sources of heavy metal contamination in lead-zinc mining areas. To study the effects of Ethylene Diamine Tetracetic Acid (EDTA) and Diethylene Triamine Penlaacetic Acid (DTPA) on phytoremediation of lead-zinc mining area soil, two chelators (EDTA and DTPA) were used in enrichment plant ryegrass to improve the uptake of Pb and Zn from soil. The results showed that when the doses of 0, 0.5, 1 and 2 mmol/kg EDTA and DTPA were used, the biomass of ryegrass (Lolium multiflorum Lam.) and its nutrient (N, P, K, Ca and Mg) content increased, whereas EDTA and DTPA with a dose of 4 mmol/kg decreased the biomass of ryegrass and its nutrient (N, P, K, Ca and Mg) content. EDTA and DTPA significantly enhanced the contents of Zn and Pb in ryegrass as compared with the control. As for Pb, the content of Pb in root and shoot reached a maximum of 2730.54 and 2484.42 mg/kg respectively when the dose of EDTA and DTPA was 2 mmol/kg. In the case of Zn, the content of Zn in root and shoot reached a maximum of 2428.37 and 2010.43 mg/kg respectively. The total Pb and Zn accumulations and translocation ratio in ryegrass had also been enhanced. The results indicated that EDTA and DTPA had great potential to be used for ryegrass to remedy Pb and Zn contamination soil of lead-zinc mining area, but should be used cautiously because of their environmental risks.
... Shu et al. (2000) noted that there are over 8,000 national and 230,000 private mining companies in China that have created over 2 Mha of derelict land over the past 50 years; Guo et al. (1989) determined that the current rate of derelict land formation from mining in China was 20,000 ha/year; and projected that dereliction had increased to 33,000 ha/year by the end of the past century. Li (2006) Wong and Luo, 2003); and that amount was increasing by ∼47,000 ha/year ( Bai et al., 1999). ...
Lead contamination in China has been extensively documented by scientists in China and elsewhere over the past two decades, as summarized in this review of articles published in peer-reviewed scientific journals. Sources of that contamination include (a) deposits from previous emissions of leaded gasoline, which was finally eliminated in the past decade; (b) previous and continuing emissions from fossil fuel combustion, which are increasing markedly with the rapid industrialization of China; (c) previous and continuing emissions from other industrial activities, including mining, smelting and municipal waste incineration; and (d) previous and continuing additions of contaminated fertilizers, sewage, and untreated wastewater to agricultural fields. Lead concentrations of some Chinese agricultural produce are also elevated by acid rain and acidic fertilizers, which increase the solubility and bioavailability of both natural and contaminant lead in soil. In addition, some Chinese products are contaminated with lead during their production, processing, packaging, and transport. As a consequence of the long-range transport of industrial lead emissions from China and the global market for its products, the problem of lead pollution in China is a global problem.
... Unless sufficient treatments, e.g. separation layer, cover of guest soil over 50 cm deep (Wong and Luo, 2003), and/or substantial substrate amendments (Li, 2006), are exercised, growing agronomic plants may be of high risk. This utilitarianism-oriented rehabilitation of metal-mined wasteland needs to be carefully reconsidered in China because it is not only costly, but also not good for restoration of premining biodiversity. ...
Heavy metal contamination of metal-mined soils is a widespread problem in China. In the restored (over 20 years) Lipu manganese mineland, 36 plant species from 22 families were found colonizing, some of which were planted agronomic ones. Heavy metal concentrations in tailings were very high. Minesoils were basically unpolluted, but soils in the remaining mining area and in the vicinity of tailings dumps were polluted by Cd and Mn. Measurements of metal contents in dominant plants showed they were close to those of other mineland plants. Plants tended to have a higher Cd accumulation (as reflected by Biological Accumulation Coefficient) from soil, but have a higher Mn translocation (as indicated by Biological Transfer Coefficient) to aboveground parts. The Chinese chestnut and sugarcane cultivated on the reclaimed mineland were not safe for human consumption, and this agricultural restoration pattern should be carefully reconsidered.
Man-land relationship research, as the core of geographical research, runs through each development stage of Geography. Based on extensive literature review, this paper systematically generalizes the connotations, research development and contents of man-land relationship in China. (1) It explores the connotations and evolvement rules of man-land relationship in different social development stages in China, and finds that the core role of man-land relationship in geographical research has been strengthened continuously. Changing with times, its connotations have been considerably enriched by sustainable development and other notions, and so does its theoretical system. (2) It applies the bibliometric method to sketch out the basic research status of man-land relationship in China. Specifically, it quantitatively identifies the funding sources, major research teams and journals for publication. It finds that the funding sources show a diversification trend with national funding being the primary source of research grants. The most competitive research teams are mainly concentrated in the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS) and normal universities. Journals sponsored by The Geographical Society of China are most influential in publishing man-land relationship research. (3) As resources and environment are the fundamental carriers of man-land relationship, this study focuses further on the research on resource-environmental base of man-land relationship, and finds that the resource-environmental base research in China has gone through an evolution process from single factor perspective research to comprehensive multiple perspective research gradually. Research themes have also experienced similar changes from land, water, energy minerals or other single factor research to comprehensive factor research of resources and environment. Empirical study on national and regional development strategies is the feature of man-land relationship in China. More emphasis should be put on considering and following the changes in features of “man” and “land” and research on the impacts of new factors on man-land relationship in a developing and dynamic manner in the future. Particularly, we should pay more attention to research on the impacts of spatio- temporal changes in resource-environment absolute location on modes of man-land interaction, and to strengthening interdisciplinary research and systematic research on comprehensive techniques so as to advance the development of application of man-land relationship theories and practices.
Panxie mining area with high groundwater level is a coal seam group mining area. With the large amount exploitation of coal underground, the land subsidence causes the variation of ecological environment. This study is based on investigations and combined with the production planning of the mining area, adopted mining subsidence area forecast technology, Geospatial Information Systems and Remote Sensing technology. The evolvement trend of land and water systems in Huainan mining area was analyzed and the countermeasures was proposed. Results show the area ratio of subsidence zone decreases rapidly while the area ratio of water body increases rapidly. Water area of Panxie mining area (not included building land for protecting coal pillar) is equal to 100 West Lakes in China, up to 597.6 km2; and the water storage capacity is equal to 3 Tai Lakes in China after mining processes, up to 143.6 billion cubic meters. The ecosystem structure was changed from terrestrial ecosystem to water and land compound ecosystem. In view of this, a reclamation and ecological rehabilitation system was proposed, which combines the reconstruction of wetland ecosystem, the construction of ecological agriculture and other governance model, the full use of the subsidence area and the improvement of the ecological environment. The subsidence area is developed into a water storage project combined with the conditions of subsidence water area, natural lake and water system, to improve the situation of regional water resource shortage.
In a greenhouse pot experiment, the dose-response effects of limestone addition (mass fractions 0, 0.1%, 0.25%, 0.5% and 1.0%) on the growth performance and metal uptake characteristics of Jatropha curcas L. grown on different multi-metal contaminated, strongly acid soils from Dabao Mountain mine were studied. Factors suppressing plant growth as well as the feasible dosage of limestone are also discussed. In the soils with lower levels of pollution, high bio-availabilities of Cu and Pb appeared to be the primary factors inhibiting the growth of Jatropha curcas L., while in highly polluted soils, the growth inhibition of Jatropha curcas L. mainly resulted from the high bio-availability of Cd, Cu and Zn, as well as Al toxicity caused by the strong acidity. The growth performance of Jatropha curcas L. was improved both in the lower and highly polluted soils by the increase of soil pH and decrease of bio-available metal contents (Cd, Cu, Pb, Zn and Al) achieved by the addition of limestone. The optimum dosage of limestone was 0.25% for soils with lower pollution levels and 0.5% for soils with higher pollution levels. The concentrations of Cd, Cu, Pb, Zn and Al in the shoots and roots of Jatropha curcas L. were reduced to different extents by the limestone and basically decreased with the increasing amount of limestone. The metal concentrations in roots were higher than in shoots, and the drop in metal concentrations (except Cd) caused by the limestone was higher in roots than in shoots. Therefore, the combination of planting Jatropha curcas L. and limestone amendment is one of the most effective ways to remediate acid soils from Dabao Mountain which are polluted with multiple heavy metals.
On the basis of field visits of the ecological reclamation projects in the United States abandoned coal mine, along with the relevant literature, we reviewed the current practices in the United States on their management, funding usage, and the technical route of the ecological reclamation and restoration of mine waste. Engineering measures of ecological restoration for abandoned coal mine were described with several examples. A new idea named "Geomorphic Reclamation" was introduced as a fundamental shift in the current theory and practice of ecological restoration of mining sites, which is an integrated approach, learning from Nature, along with the combination of geomorphic, topological, soil, ecological, hydrologic and climate/weather conditions, for the planning, design and implication of ecological reclamation and restoration. We address the potential of Geomorphic Reclamation in China and outline how such positive and potentially far-reaching impact approach can be used in Chinese mining restoration and management.
This study focused on the technical measures of revegetation on ferrum tailings bank in Huludao, China. Adopting field test method, a revegetation trial was conducted on the Yangjiazhangzi waste ferrum tailings bank. By composting the urban sludge + river mud + straw inside planting pit to ameliorate tailings matrix, planting perennial herb to establish closed type sand barrier to shelter bush-herbage growth, transplanting nutrition cup bush seedlings and sowing herbage seed on the composting pit to establish bush-herbage clump, these technical measures can solve the major constraints to plant growth and establish survival bush-herbage vegetation at lowcost. The results show that Pit layered composting is the cost-effective measure to improve ferrum tailings planting matrix; Planting perennial herb sand barrier t is a good measure to improve microhabitat; Planting bush-herbage clump is a good pattern to resist the extreme ferrum tailing environment; Hippophae rhamnoides Linn., Caragana Korshinskii Kom., Medicago sativa Linn.and Astragalus adsurgens Pall are good pioneer species for revegetation on the ferrum tailings bank. Experiment proved that the combination of these technical measures can reconstruct vegetation, this revegetation pattern is worthy of reference for similar mine ecological restoration.
Agronomic crops grown on the reclaimed metal-mined wastelands are a pathway for toxic pollutants entering the human food chain. Agricultural rehabilitation of mine spoils in China is pretty common and its effect has been largely overlooked. Extensive sampling of the edible crops and associated soils have been conducted for the three typical manganese mine wastelands (Bayi, Lipu and Pingle) in Guangxi, south China and heavy metal contamination of crops was assessed against China Food Safety Standards. Simple pollution index (Pi) assessment indicated no Zn (except tea) and Cu pollution among these crops, but heavy pollution of Pb, Cd and Cr was found. Composite pollution index (Nemerow index, PN) showed 36 crops from 41 were heavily polluted with heavy metals. Peanut, soybean, Chinese chestnut, persimmon, cassava, mandarin and sugarcane were the most severely contaminated crops. Consumption of these crops may pose a health risk for humans. Crops tended to have a higher Cd accumulation (as indicated by Biological Accumulation Factor) in edible parts, thus Cd is the most important food safety threat. In terms of China Soil Quality Standard (class II), the minesoils contained much higher Cd and Cr levels, not suitable for agricultural plantation. Simple reclamation for crop plantation on minesoils is legally untenable and must be strictly controlled by the local governments. In addition, more diverse restoration goals with lower environmental risk should be encouraged for the mine wastelands in South China.
The changes of nitrogen components in wastelands of copper mine tailings were investigated with the samples collected from the copper mine tailings under different plant communities after natural drying, grinding and sieving in indoor. The inorganic nitrogen content of these samples was determined after extraction using 2mol/L KC1, whereas organic nitrogen content was measured by Bremner approach. The results showed that the total nitrogen (TN) content was 40.9 - 1366. lmg/kg in which total inorganic nitrogen content was 1.7 -8. 8mg/kg, accounting for TN of 0. 5% - 4. 3%; acidic hydrolysable nitrogen content was 20. 8 - 361. 4mg/kg, accounting for TN of 20. 3% - 51. 9%; acidic unhydrolysable nitrogen content was 20. 1 - 1004. 7mg/kg, accounting for TN of 48. 1% - 79. 7%. A remarkable difference was observed in the inorganic and organic nitrogen contents among the samples. In the inorganic nitrogen components, the content ranges were 1.7 -3. Omg/kg for ammonium nitrogen, undetectable -5. 8mg/kg for nitrate nitrogen and 0. 019 -0. 038mg/kg for nitrite nitrogen, which respectively occupied 0.2% -4. 2%,0 - 1. 8% and 0. 003% -0. 057% of TN. The contents of inorganic nitrogen components in the upper layer of copper mine tailings gradually increased as the eco-system development from bare lands -<cryptogamic crusts-<vascular plant communities, and followed the order of bare lands < cryptogamic crusts < vascular plant communities. But in terms of vascular plant communities, the percentage of total inorganic nitrogen in TN in the upper layer of copper mine tailings decreased with the increase of plant community development time. Data analysis showed that in the early successional bare lands and cryptogamic crusts, ammonium nitrogen mainly exists as a main form of available nitrogen, whereas the nitrate nitrogen is the main form of available nitrogen in the tailings under vascular plant communities, occupying above 60. 0% for total inorganic nitrogen. The acidic hydrolysable nitrogen and acidic unhydrolysable nitrogen accumulated gradually with the succession of plant communities and the increase of vascular plant community development time. In the acidic hydrolysable organic nitrogen components, the content ranges were 4.7 - 95.7 mg/kg for amino acid nitrogen, 5. 8 - 37. 3mg/kg for ammoniacal nitrogen, 8. 2 - 38. 8mg/kg for aminosugar nitrogen and 2. 1 - 194. 6mg/kg for unknown nitrogen, which respectively occupied 7. 2% - 11. 9%, 2. 8% - 14. 1%, 2. 5% -20. 1% and 3.4% -19. 7% of TN. The percentage of acidic unhydrolysable nitrogen, as the main parts of organic nitrogen in addition to the samples from Yangshanchong bare land, in TN increased simultaneously with the succession of plant communities and the extension of the disposed time of copper mine tailing, but an contrary trend was displayed in the percentage of acidic hydrolysable nitrogen in TN. At present, organic matter and TN content in the wastelands of copper mine tailings are still at a low level and the formation and accumulation of nutrients in the wastelands of copper mine tailings are still in its early stages. The accumulation process of organic nitrogen (in particular, acidic unhydrolysable nitrogen) is the main accumulations of nitrogen in copper mine tailings.
Two Elsholtzia haichowensis populations, one from a copper mine (CS) and the other from an uncontaminated site (UCS), were studied in hydroponic experiments for the plant growth, copper accumulation and mineral nutrients content under excess copper, nutrient deficiency and their interaction. The growth of UCS population was significantly inhibited by excessive Cu, nutrient deficiency and their interaction. But the growth of CS population was less affected by these factors, and 25μmol/L Cu stimulated significantly the growth of CS population. The tolerance indices of root length to Cu and biomass to mineral nutrient deficiency in the CS population were significantly higher than that in the UCS population. The results indicated that the CS population had evolved not only Cu tolerance but also tolerance to low nutrient supply. Nutrient deficiency increased significantly Cu uptake and transport in two populations. For example, at 25μmol/L Cu mixed with nutrient deficiency, root-Cu content of CS population was about 25 times that of CS population at 25μmol/L Cu treatment; root-Cu content of UCS population at interaction of 25μmol/L Cu and nutrient deficiency was more than 5 times that of CS population at 25μmol/ L Cu treatment. Shoot-Cu contents in two populations also increased, but that in UCS population increased much more than in CS population. Excessive Cu reduced significantly uptake and transport of mineral nutrient including P, Mg, K and Mn. But contents of these mineral elements in CS population was less affected by excessive Cu. At interaction of nutrient deficiency and Cu (25μmol/L), mineral element contents except Ca and some Fe decreased significantly. But the reduction in CS population is less than that in UCS population. The results indicated that the mineral composition homeostasis under the stresses was important in metal tolerance and colonizing normally in the Cu-enriched soils for the Cu-tolerant population.
Both coal mine and land are important natural resources that human depend on for existence and development. Coal mining has contributed greatly to the development of economy and society in China. Meanwhile, subsidence induced by coal mining has seriously affected human life, ecological environment and development of regional economy in mining area. Thus, aiming at coal mining subsidence area, this paper puts forward two kinds of land reclamation techniques containing engineering reclamation technology and biological reclamation technology, which can scientifically guide land reclamation practice, coordinate relationship between human and land and relax ecological crisis.
To understand the effects of afforestation on physical properties of iron tailings, this study analyzed the difference in physical properties (including moisture content, bulk density, property and the texture) among iron tailings under different plantations, farmland soil and natural soil under shrub. The results show that the moisture content and the field moisture content of iron tailings were significantly lower than that of farmland soil, but the moisture content and field capacity of iron tailings under Hippophae rhamnoides plantation and Amorpha fruticosa plantation were higher than that of new tailings. The bulk density of all iron tailings were significantly higher than that of nature soil in shrub, and the former were 1.31-1.53 times the latter. The total porosity of iron tailings were significantly lower than that of natural soil, and the latter was approximately 1.12-1.20 times the former, but for non-capillary porosity, the former was 3.13-3.94 times the latter. Moreover, the percentage of fine mineral particles of iron tailings surface under plantations was higher than that of new tailings obviously, and for the percentage of coarse mineral particles, the former was lower than the latter. These results suggest that the texture of iron tailings become finer after afforestation, but this change happens only in surface tailings, rather than deep tailings. It is concluded that iron tailings contain more coarse mineral particles and have more coarse texture and higher non-capillary porosity, which causing lower abilities of water and fertility retention than nature soil, such as in shrub, but afforestation can improve these physical properties obviously.
Zn accumulation and subcellular distribution in leaves of the hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of Sedum alfredii Hance were studied using radiotracer and gradient centrifugation techniques. Leaf Zn accumulation in the HE of S. alfredii was 18.5-26.7 times greater than that in the NHE when the plants were grown at 1-500 μmol Zn L−1. Leaf section uptake of 65Zn was highly dependent on external Zn levels. Greater 65Zn uptake in HE was noted only at external Zn levels ≥100 μmol L−1. Zinc subcellular distribution in the leaves of the two ecotypes of S. alfredii was: cell wall > soluble fraction > cell organelle. However, more Zn was distributed to the leaf cell wall and soluble fractions for HE than for NHE. In the leaf of HE, 91%–94% of the Zn was found in the cell walls and the soluble fraction and only 6%–9% Zn was distributed in the cell organelle fraction. For NHE, about 20%–26% Zn was recovered in the cell organelle fraction. In stems, Zn distribution to the cell wall fraction was approximately two fold greater in the HE than that in the NHE. For the hyperaccumulating ecotype of S. alfredii, the cell wall and the vacuole played a very important role in Zn tolerance and hyperaccumulation.
Umweltverschmutzung, Urbanisierung sowie die Versorgung der noch immer wachsenden Bevölkerung sind große Herausforderungen für Chinas Nahrungsmittelpolitik im 21. Jahrhundert. Diese Publikation zeichnet verschiedene Aspekte im Zusammenhang mit Nahrungsmitteln in China nach - von der Produktion über den Konsum bis hin zur Entsorgung. Dabei stehen vor allem Food safety und Food security im Mittelpunkt, aber auch Chinas Rolle auf den weltweiten Nahrungsmittelmärkten. Die Aktivitäten nichtstaatlicher Akteure rund um Nahrungsmittel- und Versorgungssicherheit in China bilden einen weiteren Schwerpunkt der vorliegenden Publikation. -- Pollution, urbanization as well as the continuous growth of the population challenge China's food policy of the 21st century. This publication takes a closer look at different aspects of Food in China - from production to consumption to waste management. The focus lies in particular on food safety and food security but also on China's role in global food markets. Moreover, this publication highlights the activities of non-state actors in the realm of food safety and food security in China.
Soil enzyme is involved in nutrient cycling and availability to plants and can be used as an index of soil function. Underground coal mining results in large-scope land subsidence, farmland damage and soil fertility decline. In this paper, Hanwang coal mining subsided area in Jiaozuo city, Henan province, China, was taken as an example to study on the soil enzyme activities in different sites and layers. The results show that: firstly, the activities of the hydrogen peroxidase, sucrase and dehydrogenase of the reference points exceed that of the points in the settlement zone. Similarly, the urease activity of the reference points except from the range within 0 to 5 cm is higher than that of the points in the settlement zone; By contrast, the difference of phosphatase activity between the reference points and the points in the settlement zone is not significant. Secondly, the variation of polyphenol oxidase, hydrogen peroxidase, dehydrogenase and urease from the points in the settlement zone is unconspicuous; there is some diversity of phosphatase activity between the points in the settlement zone, the significance of difference of invertase activity of the sampling points between No. 4 within the range of 5 to 15 cm and other sampling points in the settlement zone is great. Thirdly, there is no significant difference between the reference points with the hydrogen peroxidase and divertase activity in the stratum; by contraries, the differences in some stratum of the settlement zone was significant. There is some difference of between the hydrogen peroxidase and invertase activity of the reference points; by contrast, the diversity of the phosphatase and urease activity in the stratum in the settlement zone is increasing. The distribution of the dehydrogenase activity between the reference points and the points in the settlement zone is opposite to each other; the activity difference of the reference points within the range of 20 to 40 cm is the maximum, the differenc- e is the maximum within the range of 0 to 5 cm in the ground surface. Fourthly, the ground surface subsidence is caused by the coal mining that the soil is contaminated by heavy metals and polycyclic aromatic hydrocarbons; consequently, the enzyme activity is depressed and the soil quality is degenerated, so that the soil output is reduced.
A five-year field trial was conducted at the surrounding area of Dabao Mountain Mine to explore the feasibility and availability of using kenaf (Hibiscus cannabinus) , a fiber crop with strong heavy metals tolerance and potential economic value, to reclaim the multi-metal contaminated acidic farmland soil. Different amendments were applied prior to the kenaf planting to evaluate their effects on the soil properties and kenaf growth. After the amendments application, the kenaf could grow well on the heavy metals contaminated soil with the Pb, Zn, Cu, Cd, and As concentrations being 1600, 440, 640, 7. 6, and 850 mg . kg-1, respectively. Among the amendments, dolomite and fly ash had better effects than limestone and organic fertilizer. With the application of dolomite and fly ash, the aboveground dry mass production of kenaf reached 14-15 t . hm-2, which was similar to that on normal soils, and the heavy metal concentrations in the bast fiber and stem of kenaf decreased significantly, as compared with the control. The mass of the bast fiber accounted for 32% -38% of the shoot production, and the extractable heavy metal concentrations in the bast fiber could meet the standard of 'technical specifications of ecological textiles' in China, suggesting that the bast fiber had potential economic value. It was suggested that planting kenaf combining with dolomite/fly ash application could be an effective measure to reclaim the multi-metal contaminated acidic farmland soil.
Food security is essential for the economic, political and social development of a country. This paper
analyzes the current Food security situation in China and addresses the following three issues: The cur-
rent situation with regard to food supply, the factors which limit food security, and finally who is affected
by food insecurity. In our discussion, we point out the reaction of the Chinese government to threats for
food security and highlight the significance of the 120 million hectare threshold of agricultural land.
We conclude with the analysis of the interrelationship between poverty, infrastructure and food security.
Based on investigation of the characteristics of solid waste of two different mines, the Fenghuangshan copper mine and the Xinqiao pyrite mine in Tongling, Anhui province in central-east China, the possibility and the differences of acid mine drainage (AMD) of the tailings and the waste rocks are discussed, and the modes of occurrence of heavy metal elements in the mine solid waste are also studied. The Fenghuangshan copper mine hardly produces AMD, whereas the Xinqiao pyrite mine does and there are also differences in the modes of occurrence of heavy metal elements in the tailings. For the former, toxic heavy metals such as Cu, Pb, Zn, Cd, As and Hg exist mostly in the slag mode, as compared to the latter, where the deoxidization mode has a much higher content, indicating that large amounts minerals in the waste rocks have begun to oxidize at the earth surface. AMD is proved to promote the migration and spread of the heavy metals in mining waste rocks and lead to environmental pollution of the surroundings of the mine area.
Thirty-nine rhizobial isolates were isolated from the root nodules of Glycyrrhiza uralensis and Glycyrrhiza glabra, growing in the arid and semiarid regions of northwestern China, to test their taxonomic position and stress tolerance and to select one promising putative inoculant strain for further studies. On the basis of 113 physiological and biochemical characteristics, the isolates were clustered into three groups. One isolate CCNWGX035 was found to have high tolerance to NaCl, pH, and temperature. By sequencing the 16S rDNA, isolate CCNWGX035 was placed in genus Mesorhizobium. Nodulation tests demonstrated that the isolate not only formed nitrogen-fixing nodules on its original host plant Glycyrrhiza glabra, but also on Sophora viciifolia, Lotus corniculatus, Trifolium repens, Melilotus suaveolens, and Sophora alopecuroides. On the basis of sequence analysis of the nodA gene, isolate CCNWGX035 was closely related to strains of the genus Mesorhizobium, exhibiting some novel characteristics of root nodule bacteria.
Two Rumex japonicus populations, one from a copper mine and the other from an uncontaminated site, were studied in hydroponic experiments for the plant growth, copper accumulation and mineral nutrient content under excess copper and nutrient deficiency conditions. The tolerance indices of the contaminated population were significantly higher than that of the uncontaminated population, indicating the evolution of Cu resistance in the former. At control and low Cu treatment, there was no difference in Cu accumulation in roots between the two populations. At high Cu (100 μM) treatment, however, the contaminated population accumulated less Cu in roots than the uncontaminated one, suggesting the root exclusion mechanism existing in the former. The contaminated population was also more tolerant to general nutrient deficiency than the uncontaminated one. The results indicated that the contaminated population had evolved not only Cu-tolerance but also tolerance to low nutrient supply. Under Cu stress, the contaminated population had less change in nutrient composition than the uncontaminated one. The similar result was observed in general nutrient deficiency experiment. The results indicated that the mineral composition homeostasis under the stresses was important in metal tolerance and colonizing the Cu-enriched soils for the Cu-tolerant population. At high Cu (100 μM) treatment and general nutrient deficiency treatment, the contaminated population accumulated significantly lower copper and higher phosphorus in both roots and shoots than the uncontaminated one. This was not the case for other mineral nutrients Ca, Mg and Fe except for root Mg and root Fe at Cu treatment. The result suggested that the high Ca-metabolism in R. japonicus was uncorrelated with high Cu-tolerance and that P might play an important role in governing Cu bioaccumulation.
Bio-crust is the initial stage of natural primary succession in copper mine tailings. With the Yangshanchong and Tongguanshan copper mine tailings in Tongling City of Anhui Province as test objects, this paper studied the soil microbial biomass C and N and the activities of dehydrogenase, catalase, alkaline phosphatase, and urease under different types of bio-crust. The bio-crusts improved the soil microbial biomass and enzyme activities in the upper layer of the tailings markedly. Algal crust had the best effect in improving soil microbial biomass C and N, followed by moss-algal crust, and moss crust. Soil microflora also varied with the type of bio-crust. No'significant difference was observed in the soil enzyme activities under the three types of bio-crust. Soil alkaline phosphatase activity was significantly positively correlated with soil microbial biomass and dehydrogenase and urease activities, but negatively correlated with soil pH. In addition, moss rhizoid could markedly enhance the soil microbial biomass and enzyme activities in moss crust rhizoid.
Despite a principal contributor to the rapid economic growth, the mining industry in China produced a large amount of wasteland and caused water pollution and soil erosion as well as other environmental damages. In 2002, this industry generated 265.4 Mt tailings, 130.4 Mt gangue and 107.8 Mt smelting slags. The degraded land associated with mining is estimated to be 3.2 Mha by the end of 2004, deteriorating the land shortage of China. Restoration of mine wasteland began in late 1970s but the restoration process was sluggish. The overall restoration rate (the ratio of reclaimed land area to the total degraded land area) of mine wasteland was some 10-12% with a higher rate for coal mine spoils but a lower rate for metal-mined derelict land. From 1994 to 2004, 149 research papers were published about the restoration of China's mining wasteland, of which 70 were on metal-mined land and 61 on the non-metal-mined land. Although 37 institutions in China were involved in the restoration research, only a few remained active and productive. Metal-mined derelict land is often more metal toxic and deficient of macronutrients and is tougher for revegetation. Many substrate amelioration techniques were proposed and tolerant plant species were tested for use of reclamation of the metal-mined tailings. Five hyperaccumulator species have been reported in China for the potential use in phytoremediation. However, these accomplishments were all at laboratory or small-scale field demonstration stage and still far from the practical use in reality. To accelerate the restoration and utilization of mine wasteland, several recommendations are put forward in this review. Above these suggestions, the commitment and efficiency of the government at all levels are vital.
A survey on the crops grown on the restored manganese mine lands in Pingle and Lipu of Guangxi was conducted, and the heavy metal concentrations in the edible parts of the crops were analyzed. The results showed that the heavy metal concentrations in the crops were 1.18-20.46 mg x kg(-1) for Zn, 0.52-16.16 mg x kg(-1) for Pb, 0.33-6.62 mg x kg(-1) for Cr, 0.01-6.24 mg x kg(-1) for Cu, and 0.01-2.76 mg x kg(-1) for Cd. Among the crops, beans had the highest concentrations of almost all test metals, followed by potatoes. The assessment of single factor pollution indices indicated that in the main, the crops were not polluted by Zn and Cu, but heavily polluted by Pb, Cr and Cd, with the pollution rate being 100%, 96.9% and 75.0%, respectively. Comprehensive pollution index indicated that all the crops were polluted by heavy metals, with the heavy, medium and light pollution grade being 87.5%, 9.4% and 3.1%, respectively. Planting edible crops directly on manganese mine wastelands might have great risk for human health, and the existing restoration patterns should be reconsidered.
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