华南铅锌尾矿生态恢复的理论与实践

介绍了近年来有关华南地区5个铅锌尾矿生态恢复研究领域的主要研究成果。内容包括：铅锌尾矿的理化性质和影响植物定居的限制因子;尾矿酸化的预测与控制;尾矿的基质改良;尾矿自然定居植物的生态对策;重金属耐性植物的筛选与耐性机理;豆科植物在废弃地植被恢复中的作用;尾矿湿地系统的重建及其废水处理效率;土壤种子库在尾矿生态恢复中的作用;尾矿植被恢复的野外中试研究等。同时,也讨论了尾矿废弃地生态恢复的未来研究方向。     

香根草在铅锌尾矿上生长及其对重金属的吸收

通过野外小区实验 ,研究了垃圾和 NPK肥对铅锌尾矿地中香根草 (Vetiveria zizanioides)生长及其对重金属吸收的影响。结果表明 ,添加垃圾后香根草生物量显著增加 ,而仅加入 NPK肥对其并无显著影响 ,同时添加垃圾和 NPK肥最有利于香根草在铅锌尾矿中生长。尾矿中重金属形态的变化受金属特性和尾矿理化性质的双重影响。对纯尾矿而言 ,种植香根草后尾矿中重金属总量有所减少。尾矿在施加垃圾和 NPK肥后 ,尾矿中 Pb和 Zn总量减少了 13.6 5 %和 32 .4 0 % ,Cu总量则增加了2 3.5 2 %。可交换态和总量 Cu、Pb、Zn变化趋势一致 ,特别是 Cu和 Pb更为显著。香根草积累的 Pb和 Zn显著高于 Cu,并且重金属主要积累在根部。添加垃圾和 NPK肥料对 Cu的积累无显著差异 ,而显著减少香根草茎和根中 Zn和 Pb的积累 ,但显著增加单位面积上茎中 Zn、Pb和 Cu的总积累量 (p<0 .0 5 )。研究表明垃圾和 NPK肥的综合使用是一个较为经济有效的尾矿改良措施 ,但对于尾矿 -植被系统中的重金属迁移问题应引起关注。综合生物量与重金属的吸收特征 ,香根草对于尾矿的植被重建有较高价值     

Phytoremediation potential of transplanted bare-root seedlings of trees for lead/zinc and copper mine tailings

Selecting plant species that can overcome unfavorable conditions and increase the recovery of degraded mined lands remains a challenge. A pot experiment was conducted to evaluate the feasibility of using transplanted tree seedlings for the phytoremediation of lead/zinc and copper mine tailings. One-year-old bare-root of woody species (Rhus chinensis Mill, Quercus acutissima Carruth, Liquidambar formosana Hance, Vitex trifolia Linn. var. simplicifolia Cham, Lespedeza cuneata and Amorpha fruticosa Linn) were transplanted into pots with mine tailings and tested as potential metal-tolerant plants. Seedling survival, plant growth, root trait, nutrient uptake, and metal accumulation and translocation were assessed. The six species grew in both tailings and showed different tolerance level. A. fruticosa was highly tolerant of Zn, Pb and Cu, and grew normally in both tailings. Metal concentrations were higher in the roots than in the shoots of the six species. All of the species had low bioconcentration and translocation factor values. However, R. chinensis and L. formosana had significantly higher translocation factor values for Pb (0.88) and Zn (1.78) than the other species. The nitrogen-fixing species, A. fruticosa, had the highest tolerance and biomass production, implying that it has great potential in the phytoremediation of tailing areas in southern China.     

香根草和百喜草对铅锌尾矿重金属的抗性与吸收差异研究

铅锌尾矿是一类重金属含量极高,对植物生长产生毒害的生境.盆栽实验的结果显示,香根草和百喜草在纯尾矿或由尾矿和垃圾组成的混合基质上都能生长,但植物的长势随基质中重金属含量的增加而减弱,其中香根草的生物量所受的影响比百喜草的更大,即百喜草有比香根草更强的重金属抗性.2种植物体内的重金属含量高低均为Zn＞Pb＞Cu,但二者对它们的富集能力大小分别是,香根草为Zn＞Cu＞Pb,百喜草则为Cu＞Zn＞Pb.香根草和百喜草的根系对3种重金属都有较强的滞留效应,滞留率均在50%以上;其中香根草对重金属的滞留率又明显高于百喜草;而且,同一植物对不同的重金属的滞留率也明显不同,香根草对Pb的滞留率最高,而百喜草对Cu的滞留率显著高过对Zn和Pb.由于香根草的生物量明显大于百喜草,结果香根草对Pb、Zn的吸收量比百喜草高.当用25%的垃圾改良金属尾矿时,百喜草对重金属的吸收量即达最大;而香根草则在尾矿和垃圾各占50%的基质中吸收最多的重金属;因此,添加一定量的垃圾(25%～50%左右)用于尾矿改良时,不仅能使尾矿得到更快的植被恢复与更高的植物修复效果,而且能使垃圾资源得到充分合理的利用.总之,当开展对金属尾矿的植被恢复时,可选择种植抗性强、覆盖快的百喜草,但如果要对尾矿中的重金属进行生物净化,则应选择种植生物量大的香根草,种植香根草还可较好地防止重金属的二次污染或生物富集.     

Effects of earthworm (Pheretima sp.) on three sequential ryegrass harvests for remediating lead/zinc mine tailings

Farm soil and artificial soil were mixed separately with Pb/Zn mine tailings and placed in the ratios (w/w) of 0, 12.5, 25, and 50% in pots, together with 0.33 g KH2PO4 and 0.35 g urea/pot. Each pot contained 15 ryegrass seedlings (Lolium multiflorum) and 7 earthworms (Pheretima sp.). At the end of the experiment (after the third harvests of ryegrass), the earthworms were all found to be alive and burrowed completely at the bottom of the pots in all treatments. Earthworm activity increased plant biomass significantly in artificial soil/tailings mixtures in the second and third harvests as compared with the control (without addition of earthworms), but not in the farm soil/tailings mixture. The biomass of ryegrass in both soil/tailings mixtures decreased with increase of tailings, especially those containing 50% tailings. In general, the plant biomass obtained from farm soil/tailings mixtures was lower than that from artificial soil/tailings mixtures. Earthworm activity did not significantly increase DTPA-extracted Zn or Pb, in both soil/tailings mixtures. However, the concentrations in farm soil/tailings mixtures were lower in the second and third harvests, compared with the first harvest. The Zn and Pb uptake by ryegrass shoots in the two soils/tailings mixtures did not increase significantly (compared with the control) in the first and second harvests. However, in the third harvest, Zn and Pb uptake increased significantly in farm soil/tailings mixtures, but decreased significantly in artificial soil/tailings mixtures (compared with the control). The results indicated that the presence of earthworms and sequential plant harvesting could be a viable strategy for the remediation of Pb/Zn tailings.     

The influences of arbuscular mycorrhizal fungus on phytostabilization of lead/zinc tailings using four plant species

A greenhouse experiment was conducted to investigate the effects of the arbuscular mycorrhizal fungus Funneliformis mosseae on three parameters: Pb, Zn, Cu and Cd accumulation, translocation and plant growth in perennial ryegrass (Lolium perenne), tall fescue (Festuca arundinacea), showy stonecrop (Hylotelephium spectabile) and Purple Heart (Tradescantia pallida). The purpose of this work is to enhance site-specific phytostabilization of lead/zinc mine tailings using native plant species. The results showed that mycorrhizal fungi inoculation significantly increased plant biomass of F. arundinacea, H. spectabile and T. pallida. The Pb, Zn, Cu and Cd concentrations in roots were higher than those in shoots both with and without mycorrhizae, with the exception of the Zn concentration in H. spectabile. Mycorrhizae generally increased metal concentrations in roots and decreased metal concentrations in shoots of L. perenne and F. arundinacea. In addition, it was found that the majority of the bioconcentration and translocation factors were lower than 1 and mycorrhizal fungi inoculation further reduced these values. These results suggest that appropriate plant species inoculated with mycorrhiza might be a potential approach to revegetating mine tailing sites and that H. spectabile is an appropriate plant for phytostabilization of Pb/Zn tailings in northern China due to its higher biomass production and lower metal accumulation in shoots.     

Differential responses of a mine tailings Pseudomonas isolate to cadmium and lead exposures

We examined cadmium and lead resistance in Pseudomonas sp. S8A, an isolate obtained from mine tailings-contaminated soil. Resistant to soluble metal concentrations up to 200 mg l⁻¹ cadmium and 300 mg l⁻¹ lead, S8A produced both exopolymer and biosurfactant. Upon growth, this pseudomonad diverged into two morphologically distinct colony subtypes; small and round or large and flat. In the presence of lead and in the no metal control the large morphotype appeared only in late stationary phase. With cadmium the large morphotype appeared immediately following exposure. Results show that the large morphotype produced greater amounts of surfactant than the small morphotype, suggesting a unique subpopulation response to cadmium toxicity. Results also indicate that an unidentified 28 kDa protein was expressed following exposure to >10 mg l⁻¹ cadmium. This study demonstrates new links between surfactant production, differential subpopulation response and metal exposure.     

Biochemical changes in longear sunfish, Lepomis megalotis, associated with lead, cadmium and zinc from mine tailings

Longear sunfish were collected from a stream contaminated with mine tailings rich in lead (Pb), cadmium (Cd) and zinc (Zn). Blood samples were analysed for δ-aminolevulinic acid dehydratase (ALA-D) activity and Pb concentration. Vertebrae were tested for bone strength and composition, and Pb, Zn, and Cd concentrations were determined in muscle tissue. ALA-D activity was negatively correlated with blood Pb concentration ( r =–0.66), and enzyme activity was significantly higher and blood Pb significantly lower at the reference site than at the contaminated sites. Blood Pb was highly correlated with Pb in muscle tissue ( r = 0.72), and the concentrations of Pb and Cd in muscle tissues were themselves correlated ( r = 0.64). In fish from contaminated sites, two of the mechanical properties of the vertebrae measured (elastic limit and modulus of elasticity) were significantly different from values in fish from the reference site. These properties and one other (stress) were weakly correlated with muscle Cd concentration (0.42 < r < 0.46). Biochemical differences among fish from different sites were also evident; concentrations of calcium, phosphorus and collagen were lower in the vertebrae of fish from some of the contaminated sites than at the reference site, and bone phosphorus was negatively correlated with concentrations of Pb in both muscle ( r =– 0.62) and blood ( r =– 0.75). Collectively, these results indicate that, in addition to the well-documented effects of Pb on haem synthesis, other important biochemical pathways may be disrupted by continuous low-level exposure to elemental contaminants.     

Accumulation of zinc, cadmium, and lead in four populations of Sedum alfredii growing on lead/zinc mine spoils

Sedum alfredii Hance is a newly reported zinc (Zn) and cadmium (Cd) hyperaccumulator native to China. In this study,four populations of S. alfredii were collected from Yejiwei (YJW), Jinchuantang (JCT) and Qiaokou (QK) lead (Pb)/Zn mines located in Hunan Province as well as Quzhou (QZ) Pb/Zn mine located in Zhejiang Province for exploring the intraspecies difference of this plant in metal accumulation. Although they grew in the Pb/Zn spoils with relatively similar levels of Zn,Cd and Pb, remarkable differences among the four populations in tissue heavy metal concentrations were observed. The shoot Zn concentration of QZ population (11 116 mg/kg) was highest and nearly five times higher than that of the JCT population (1930 mg/kg). Furthermore, the shoot Cd concentration observed in the QZ population (1 090 mg/kg) was also highest and 144 times higher than that found in the JCT population (7.5 mg/kg). As for Pb concentrations In the shoot of different populations, a fourfold difference between the highest and the lowest was also found. Such difference on metal accumulation was opulation-specific and may be significantly explained by differences in the soil properties such as pH, organic matter (OM), and electrical conductivity (EC). Taking biomass and metal concentration in plants into consideration, the QZ, YJW and QK populations may have high potential for Zn phytoremediation, the QZ population may have the highest potential in Cd phytoremediation, and the QK population may be the most useful in Pb phytoremediation.     

Economic incentive for applying vetiver grass to remediate lead, copper and zinc contaminated soils

The application of vetiver grass (Chrysopogon zizaniodes) for phytoremediation of heavy metal contaminated soils can be promoted by economic return through essential oil production. Four levels of lead (0, 500, 2000, and 8000 mg kg(-1) dry soil), copper (0, 100, 400, and 1600 mg kg(-1) dry soil) and zinc (0, 400, 1600, and 6400 mg kg(-1) dry soil) were used to study their effects on vetiver growth, essential oil composition and yield. This study also investigated the effect of nitrogen concentrations on vetiver oil yield. Vetiver accumulated high concentrations of Pb, Cu and Zn in roots (3246, 754 and 2666 mg kg(-1), respectively) and small amounts of contaminants in shoots (327, 55, and 642 mg kg(-1), respectively). Oil content and yield were not affected at low and moderate concentrations of Cu and Zn. Only the application of Pb had a significant detrimental effect on oil composition. Extraction of vetiver essential oils by hydrodistillation produced heavy metal free products. High level of nitrogen reduced oil yields. Results show that phytoremediation of Cu and Zn contaminated soils by vetiver can generate revenue from the commercialization of oil extracts.     

Soil algal communities inhabiting zinc and lead mine spoils

Algal communities inhabiting four calamine mine spoils differing in time since cessation of exploitation and loaded with high concentrations of zinc (20,284–61,599 μg g⁻¹ soil DW), lead (2,620–3,885 μg g⁻¹ DW) and cadmium (104–232 μg g⁻¹ DW) were studied. In dump soils of slightly alkaline pH (7.28–7.52) and low nutrient (, , ) concentrations, chlorophyll a content ranged from 0.41 to 2.27 μg g⁻¹ soil DW. In total, 23 algal species were recorded. Chlorophyta were the dominant taxonomic group (42–55% of all identified species) followed by Cyanobacteria (28–36%) and Heterokontophyta (13–21%). The highest species richness (18) was observed in the oldest dump (120 years old) with natural succession, while in younger dumps it was lower (11–15). Total algal abundance ranged between 5.5 and 19.1 × 10² ind. g⁻¹ soil DW, and values of Margalef’s diversity indices (1.59–2.25) were low. These results may suggest that both high concentrations of heavy metals and low nutrient content influenced the algal communities in all the dumps studied. The differences in algal microflora observed between tailing dumps may indicate that habitat quality improved with time and that algae isolated from Zn/Pb-loaded soils may be Zn/Pb-resistant ecotypes of ubiquitous species.     

Revegetation of metalliferous mine spoil contaminated by lead and zinc

Plant growth and development on metalliferous mine spoil is restricted by the high concentrations of phytotoxic metals and by the low levels of macronutrients in the substrates. Swards established on innocuous amendments applied to the surface of mine spoil deteriorate when roots penetrate to the underlying toxic substratum. This deterioration is attributed to the accumulation of toxic metals. The rate of decline is determined by the inherent fertility of the amendment and the depth to which it is applied. Results of field trials on calcareous and acidic lead/zinc spoils indicate that inert amendments may be more suitable where revegetation is for amenity or recreational purposes. Legumes are essential components of low-maintenance swards established on substrates of low nutrient status.     

3种木本植物在铅锌和铜矿砂中的生长及对重金属的吸收

通过盆栽试验评价3种木本植物紫穗槐、桤木和黄连木修复铅锌矿和铜矿尾矿的潜力。结果表明,150d后3种植物在矿砂中都能生长,其中黄连木在铅锌矿砂中生长受到明显抑制,桤木的叶绿素含量显著降低。3种植物的根系发育在2种矿砂中没有受到显著抑制。重金属在3种植物组织中的含量为17.66 -55.36 mg/kg (铜)、2.67-196.00 mg/kg(铅)、58.93-333.67 (锌,铅锌矿砂)和49.20-199.33(锌,铜矿砂)。3种植物的生物富集系数(BCF)和转移系数(TF)值都小于1。60d后,桤木和黄连木叶片的叶绿素荧光参数与对照相比没有显著变化,PSⅡ的最大量子产量有下降的趋势。重金属胁迫后显著增加Mg、Fe、Cu在功能叶的含量,显著地降低Mn的含量。因此可利用固氮植物紫穗槐在尾矿区造林和修复。     

Amendment-assisted revegetation of mine tailings: improvement of tailings quality and biomass production

Abstract

Mining activities have left a legacy of metals containing tailings impoundments. After mine closure, reclamation of mine wastes can be achieved by restoration of a vegetation cover. This study investigated the impact of biochar (BC), biosolids (BS), humic substances (HS), and mycorrhizal fungi (MF) for improving mine tailings fertility and hydraulic properties, supporting plant establishment, tailings revegetation, and enabling growth of energy crops. We conducted a pot trial by growing willow, poplar, and miscanthus in Pb/Zn/Cu mine tailings untreated or amended with two rates of amendments (low or high input). Biosolids resulted in the most significant changes in tailings properties, neutralizing pH and increasing organic carbon, nutrient concentrations, cation exchange capacity, water retention, and saturated hydraulic conductivity. The greatest increase in energy crops production was also observed in BS treatments enabling the financial viability of mine reclamation. Although BC resulted in significant improvements in tailings fertility and hydraulic properties, its impact on biomass was less pronounced, most likely due to lower N and P available concentrations. Increases in willow and miscanthus biomass were observed in HS and MF treatments in spite of their lower nutrient content. A pot experiment is underway to assess synergistic effects of combining BS with BC, HS, or MF.     

Aerobic processes for bioleaching manganese and silver using microorganisms indigenous to mine tailings

World Journal of Microbiology and Biotechnology - Alcohol fermentation is a key process in wine, beer, alcoholic beverage production, bioethanol production by means of carbohydrate sources, and...     

Characterization of a copper-resistant symbiotic bacterium isolated from Medicago lupulina growing in mine tailings

A root nodule bacterium, Sinorhizobium meliloti CCNWSX0020, resistant to 1.4 mM Cu²⁺ was isolated from Medicago lupulina growing in mine tailings. In medium supplied with copper, this bacterium showed cell deformation and aggregation due to precipitation of copper on the cell surface. Genes similar to the copper-resistant genes, pcoR and pcoA from Escherichia coli, were amplified by PCR from a 1.4-Mb megaplasmid. Inoculation with S. meliloti CCNWSX0020 increased the biomass of M. lupulina grown in medium added 0 and 100 mg Cu²⁺ kg⁻¹ by 45.8% and 78.2%, respectively, and increased the copper concentration inside the plant tissues grown in medium supplied with 100 μM Cu²⁺ by 39.3%, demonstrating that it is a prospective symbiotic system for bioremediation purposes.     

Heavy metal localisation in mycorrhizas ofEpipactis atrorubens (Hoffm.) Besser (Orchidaceae) from zinc mine tailings

Summary The metal distribution within mycorrhizal and nonmycorrhizal roots ofEpipactis atrorubens collected from zinc mine tailings and an area rich in heavy metal ores (both located in southern Poland) was investigated. The tailings, consisting of postflotation material, were characterised by high levels of toxic elements such as Zn, Pb, and Cd, while soil outside the tailings was also strongly enriched in heavy metals. Atomic absorption spectrometry and proton-induced X-ray emission analysis revealed that heavy metals were mostly accumulated within orchid roots. Elemental maps from proton-induced X-ray emission showed that plant root epidermis and fungal coils which had developed within cortical cells of roots collected from the zinc mine tailings were the main places of Zn and Pb accumulation, associated with increased concentrations of Fe, Cd, Ti, Mn, Si, Ca, and S. The mean content of Pb and Zn in the coils was 4 to 5 times higher than in the root epidermis. In mycorrhizal roots from the tailings a statistically significant decrease in Pb and Zn content towards the inside of the root was observed. The mean content of Pb in coils from roots of plants growing outside the tailings was about 1% of the concentration in root coils from the tailings. Coils selected from orchid roots originating from a site outside the tailings contained comparatively high concentrations of Zn, Cd, and Cu, which was probably due to the high content of these elements in the soil. The results presented suggest a biofiltering effect against heavy metals by orchid mycorrhizal fungi.