Microbial diversity in acid mine drainage of Xiang Mountain sulfide mine, Anhui Province, China

To understand the composition and structure of microbial communities in acid (pH 3.0) mine drainage (AMD) associated with pyrite mine tailings in Anhui Province, China, molecular diversities of 16S rRNA and 18S rRNA genes were examined using a PCR-based cloning approach. Bacterial, archaeal and microeukaryotic clone libraries were constructed. In contrast to typical dominance of autotrophic acidophiles, genus Acidiphilium, which consists of mixotrophic acidophiles capable of chemoorganotrophic and photosynthetic metabolisms, was the largest group in the bacterial clone library. These mixotrophic organisms may be advantageous in the oligotrophic AMD environment of the study site (certain amounts of dissolved organic carbon and light) by switching between two modes of metabolisms. Unexpectedly, a large fraction of bacterial clones (12.7%) were related to the neutrophilic genus Legionella, which can cause Legionnaires’ disease, a potentially lethal pneumonia. The eukaryotic 18S rRNA gene sequences were mostly related to Oxytricha, Nuclearia, and Penicillium. In the archaeal clone library, all the sequences were affiliated to the phylum Crenarchaeota, while the Euryarchaeota was not present.     

Azadirachtin,a scientific gold mine

Azadirachtin is a highly interesting compound both for its chemical structure, which required 18 years to solve, and its synthesis, which required another 22 years, and for its biological properties as a feeding deterrent for many insects and a growth disruptant for most insects and many other arthropods. Its mode of action, structure–activity relationships, and its biosynthesis still require much research. A valuable natural pesticide, it has very low toxicity for vertebrates, and yet it has still not achieved a prominent place among pesticides and in many countries it is not yet licensed for use. An attempt is made to understand its failure to capture a larger market, 40 years after its discovery.     

Environmental control in the uranium mine Lagoa Real,Brazil

Uranium production in Brazil will be restarted in the year 2000, through exploration of the Jazida da Cachoeira, located in the uraniferous region of Lagoa Real, Bahia State, northeast Brazil. Because of the mining operations, an open cast mine of approximately 27 × 10⁴ m² will be produced and the material removed will constitute approximately 14 x 10⁶ tons, occupying an estimated area of 50 x 10⁴ m². Currently, there is a new concept about project developing, where the impact assessment is addressed during the initial phases. Beside this, legislation requires an environmental impact assessment before starting mining activities. In this context purpose, it is the purpose of this work to evaluate the chemical composition of the future waste; thus, samples were collected from the rocks that surround the mineral deposits. Instrumental neutron activation analysis was used for the elemental quantification, the mean elemental concentrations were calculated, and the ratios were normalized using North American Shale Composite (NASC). In the raw material eight main mineral structures exist whose elementary composition were compared using the statistical techniques of analysis of variance, ranking ANOVA, and multivariate ANOVA.     

Chromium bioaccumulation in rice grown in contaminated soil and irrigated mine wastewater--a case study at South Kaliapani chromite mine area, Orissa, India

The level of chromium (Cr) contamination in soils and irrigated mine wastewater at South Kaliapani chromite mine region of Orissa, (India) were investigated. Chromium bioaccumulation in rice plants (Oryza sativa L. cv. Khandagiri) irrigated with Cr+6 contaminated mine wastewater was analyzed along with its attenuation from mine wastewater. The levels of Cr+6 in irrigated mine wastewaters in successive rice grown plots were analyzed on 75 days and 100 days after transplantation of seedlings. Total chromium content in different parts of rice plants and soil samples from different plots was analyzed during harvesting stage (125 days after transplantation). Cr accumulation was significantly high in surface soils (0-20 cm) with a mean value of 11,170 mg kg(-1), but it decreased significantly after the crop harvest. About 70% to 90% reduction of Cr+6 levels was observed in irrigated mine wastewater when passed through successive rice plots. High bio-concentration of Cr in leaves with values ranging from 125-498 mg kg(-1) as compared to stem (25-400 mg kg(-1)) and grain (5-23 mg kg(-1)) was noticed. The reduction of Cr+6 levels is related to plant age, high biomass and area of water passage and was attributed to rhizofiltration technique.     

Microbial communities,processes and functions in acid mine drainage ecosystems

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Microbial distribution and diversity in saturated, high pH, uranium mine tailings, Saskatchewan, Canada

Microbiological analyses were conducted on core samples collected along a vertical profile (0-66 m below surface) from the tailings management facility (TMF) at the Rabbit Lake uranium mine in northern Saskatchewan, Canada. Bacterial numbers in the core materials were similar to surrounding soils and surface waters, regardless of the seemingly unfavorable pH (mean=9.9) and temperature (approximately 0 degrees C) in the TMF. The greatest number of viable cells (105 CFU/g) was detected at the interface between the tailings and overlying standing water, below which cell counts decreased rapidly with depth. Whole-community metabolic profiles for samples from the different depths grouped into 3 clusters; however, these groups could not be positively correlated with sampling depth, temperature, redox potential, pH, or ore-mill feed. Flow-cell studies demonstrated microbial communities in the tailings surface water could develop biofilms and maintain cell activity at both pH 10 and 7, and altering the pH between these 2 values had little effect on biofilm viability. These results demonstrate the resilience and adaptive nature of naturally occurring microbial communities and signify a potential role of microbial activity in the long-term geochemical evolution of the TMF.     

紫金山铜矿酸性矿山废水微生物群落多样性

【背景】为避免环境污染,酸性矿山废水需经处理后才能排放,处理后的废水理化性质会发生显著变化,将影响整个微生物群落的结构。【目的】分析处理前后的细菌和真菌群落变化及其与理化参数的关系,为矿山废水的处理提供参考指标,并为矿山污染场地的修复提供理论基础。【方法】采集福建紫金山铜矿的酸性矿山废水并测定其理化性质。采用基于原核微生物16S rRNA基因V4区和真菌18S rRNA基因ITS的高通量测序技术分析水样的微生物群落结构。【结果】经中和处理后的回水与矿坑水和生物浸出液相比,pH升高,重金属离子含量显著降低。原核微生物的多样性高于真菌,回水的物种多样性高于矿坑水和浸出液。回水中变形菌门的丰度最高,矿坑水和浸出液中分别以广古菌门和硝化螺菌门的丰度最高。回水中噬氢菌属为优势类群,矿坑水和浸出液中的优势菌是钩端螺旋菌属,铁质菌属等古菌也有一定的比例。pH、Al、Mn、Zn与回水中相对丰度较高的菌属显著相关,而矿坑水和浸出液中的高丰度类群与环境因子没有显著的相关性。【结论】研究表明酸性废水的中和沉淀处理对微生物群落产生了较大的影响,微生物群落变化可以作为矿山酸性废水污染处理效果的一个参考指标。     

Cultivation-dependent and cultivation-independent characterization of the microbial community in acid mine drainage associated with acidic Pb/Zn mine tailings at Lechang, Guangdong, China

Cultivation-based and molecular approaches were used to characterize the phylogenetic composition and structure of the microbial community in an extremely acidic (pH 2.0) acid mine drainage (AMD) associated with Pb/Zn mine tailings that were undergoing vigorous acid generation. Acidophilic bacteria were isolated and enumerated on solid media, and were found to be restricted to isolates related to Acidithiobacillus ferrooxidans and Acidiphilium cryptum. By contrast, cloning and phylogenetic analysis of 16S rRNA genes revealed that, although low in total taxonomically distinct groups, the tailings AMD ecosystem harbored a wide range of phylogenetically diverse microbes. Of the 141 clones examined, 104 were phylogenetically affiliated with the recently discovered, iron-oxidizing Leptospirillum group III within the Nitrospira. It thus appears that iron serves as the major electron donor in this habitat. Thirty clones were affiliated with the Proteobacteria, half of which belonged to organisms related to Alphaproteobacteria species capable of ferric iron reduction. Other clones were grouped with Betaproteobacteria and Gammaproteobacteria (six clones each), and even with Deltaproteobacteria (three clones), a subdivision with anaerobic sulfate or metal (iron) reduction as the predominant physiological trait of its members. Finally, four clones were clustered within the Firmicutes and the Acidobacteria. Approximately half of the sequence types representing the majority of the total clones fell into lineages that are poorly represented by cultured organisms or have thus far been represented by only a few environmental sequences. Thus, the present study extends our knowledge of the biodiversity of microorganisms populating highly acidic AMD environments.     

Isolation of highly copper‐tolerant fungi from the smelter of the Naganobori copper mine,an historic mine in Japan

Aims: Copper is a critical metal of modern industry, and is the most widespread heavy metal contaminant in wastewater. Therefore, isolation of copper‐tolerant microbes having the potential as biosorbent is fascinating not only from an environmental microbiology, but also from a biotechnology view point. In this study, we attempted to isolate highly copper‐tolerant microbes from soil samples of the Nabanobori copper mine, the oldest mine in Japan. Methods and Results: As a result of an enrichment culture, two fungal strains were isolated from soil of the smelter remains. The isolates could grow in a maximum of 200 mmol l^?l Cu²⁺, and grew under a wide pH range. The Cu²⁺‐binding capacity of nontreated biomass of the isolates was around 35 mg Cu²⁺ g^?1‐biomass. Analysis of 18S rDNA suggested that the isolates belong to the Aspergillus/Penicillium clade, but they represented a distinct lineage against known neighbours. Conclusion: The isolates were highly copper‐tolerant, and their Cu²⁺‐binding capacity was comparable to well‐studied fungal sorbents. The isolates were implied as novel species. Soil of the historic old mine under weather‐beaten conditions might be a suitable source for metal‐tolerant microbes. Significance and Impact of the Study: The present results advance our understanding of metal‐tolerant microbes, and offer a new tool for both environmental control and metal recovery operations.     

Molecular diversity of microbial community in acid mine drainages of Yunfu sulfide mine

Two acid mine drainage (AMD) samples were studied by a PCR-based cloning approach, which were from Yunfu sulfide mine in Guangdong province, China. A total of 15 operational taxonomic units (OTUs) were obtained from the two AMD samples. The percentage of overlapped OTUs in two AMD samples was 42.1%. Phylogenetic analysis revealed that the bacterium in the two samples fell into four putative divisions, which were Nitrospira, α-Proteobacteria, β-Proteobacteria, and γ-Proteobacteria four families. Organisms of genuses Acidithiobacillus and Gallionella, which were in γ-Proteobacteria family and β-Proteobacteria family, respectively, were dominant in two samples. The proportions of clones affiliated with Gallionella in each sample were 47.2% (G2) and 16.9% (G1). The result suggested that organisms of Gallionella were a very important composition in microbial communities of the two AMD samples we studied. In addition, the PCR amplification of archaeal 16S rDNA genes form these two AMD samples have been performed with two sets of archaea-specific primers, but no PCR product found. Zhiguo He, Shengmu Xiao, Xuehui Xie, and Hui Zhong equally contributed to this work.     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

Leaf breakdown, detrital resources, and food webs in streams affected by mine drainage

Breakdown of leaf litter is essential for providing detrital resources for food webs but can be impaired by anthropogenic activities, which may disrupt energy flow to consumers. We investigated the relationship between leaf breakdown and food web structure in 12 streams with or without mining impacts on South Island, New Zealand. Six streams received inputs of acid mine drainage (pH 2.5–4.9), three were naturally acidic (pH ~5.0), and three were circumneutral (pH ~6.8). Streams affected by mining either had highly acidic water (pH <3) or iron precipitates present on substrata. Breakdown rates of leaves were significantly lower in mining-affected streams than circumneutral (by almost 50%) but not naturally acidic streams and were driven primarily by microbial activity, as shredding invertebrates were often absent. Mining-affected stream webs were simplified structures with fewer species and links than those in other streams. With few species to process leaf litter and transfer detrital resources, inputs of AMD disrupted both the mechanisms responsible for breakdown and links for energy flow. While faster breakdown rates were associated with larger food webs, limited function maintained in mining-affected streams was sufficient to support primary consumers and small food webs.     

Water quality and plankton periodicity in two contrasting mine lakes in Jos,Nigeria

Water quality and plankton periodicity was studied in two mine lakes near Jos in the younger granite area of Plateau State, Nigeria. The investigation was carried out for 8 months. Transparency, pH and NO₃-N were significantly higher in Lake II while DOM, alkalinity, PO ₄ ^3– -P, BOD and chloride were significantly higher in Lake I. The order of dominance in Lake I was Bacillariophyceae, Cyanophyceae, Chlorophyceae and Dinophyceae while for Lake II; Chlorophyceae, Cyanophyceae, Bacillariophyceae and Dinophyceae. In Lake I the zooplankton in order of dominance were Cladocera, Rotifera, Copepoda, and nauplii and in Lake II Cladocera, Copepoda, Rotifera and nauplii. Although both lakes would seem unproductive based on the PO ₄ ^3– -P and NO ₃ ^– -N levels, Lake I appears more productive than Lake II.     

安徽某铁矿不同矿山废水库中微生物群落结构特征

【目的】研究安徽某铁矿不同矿山废水库中微生物群落结构特征及其影响因素。【方法】对比分析了该铁矿3个大型废水库的地球化学特征,并用高通量测序技术研究了水体中微生物群落组成,进而用统计学方法解析了环境因子对微生物群落结构的影响。【结果】3个废水库中有2个为酸性,1个为中性,理化性质有明显的差异。近年形成的塌方采场废水库(TF) pH仅为2.55±0.01,Fe浓度高达154.95±0.78mg/L,SO_4~(2–)浓度为3374.86±3.81mg/L;形成于20世纪70年代的排土场废水库(PT)酸性略弱(pH 2.9±0.02),Fe浓度(34.57±4.00 mg/L)与TF相比明显降低,SO_4~(2–)浓度则高达10398.98±626.70 mg/L;东沙采场废水库(DS)则为中性(pH7.55),但SO_4~(2–)仍高达4162.99mg/L,主要的金属离子为Mg(594.90 mg/L)、Ca (650.10 mg/L)。3个废水库的原核生物多样性随pH的升高而升高。两个酸性废水库的原核生物组成较为接近,但TF的化能自养菌含量较高(69.54%±2.89%),PT的化能异养菌含量较高(64.45%±13.81%)。自养铁氧化菌Ferrovum在TF中的比例高达(64.17±1.84)%,在PT中则下降为(35.39±13.74)%。但PT中含有丰富的化能异养嗜酸菌如Acidicapsa(15.75%±3.99%)、Acidiphilium(10.65%±2.05%)、Acidisphaera (6.34%±1.02%)等。DS中虽然也含有较高的金属离子和SO_4~(2–),但其中的原核生物组成与TF和PT截然不同,主要为Limnohabitans (18.47%)、Rhodobacter (8.42%)等。3个废水库的真核生物群落主要由藻类组成,酸水库TF和PT中主要为棕鞭藻属(Ochromonas)和胶球藻属(Coccomyxa),棕鞭藻属在TF中(53.65%±2.02%)占优势,胶球藻属在PT中(68.84±10.4%)占优势,中性废水库DS中则主要是小环藻属(Cyclotella)(49.85%)。经统计学分析,pH是影响矿山废水微生物多样性和群落组成的主要环境因素。     

Arsenic, antimony, and bismuth uptake and accumulation by plants in an old antimony mine, China

Arsenic (As), antimony (Sb), and bismuth (Bi) are metalloids that share similar chemical properties, the objective of this study was to characterize the uptake and accumulation of these metalloids by plants colonized on heavy contaminated sites in an old Sb mine. Sixty-five plant samples from seven species as well as the associated soil samples were collected at ten sites of Xikuangshan (XKS), Hunan province, China. Concentrations of As, Sb, and Bi in plants and soils were measured. As, Sb, and Bi were found to be evidently elevated due to the long history and intensive mining and smelting activities; the respective ranges for the levels of As, Sb, and Bi at the sites were 40.02-400.2?mg?kg(-1) As, 610-54,221?mg?kg(-1) Sb, and n.d. to 1,672?mg?kg(-1) Bi. No correlation was found between As and Sb at the sites, while Bi was found to be positively correlated with As whereas negative with Sb at the sites. In general, the contents in the plants in XKS were in the order of As?>?Sb?>?Bi, and the contents of As was positively correlated with Sb and Bi in plants. The highest contents of As and Sb recorded was 607.8?mg?kg(-1) As in Pteris vittata and 90.98?mg?kg(-1) Sb in Hippochcaete ramosissima, while the highest Bi content as 2.877?mg?kg(-1) Bi was measured in Buddleja davidii. Bioconcentration factors defined as the ratios of metalloids in shoots of plants to those in soils for various plants were lower than 1. The results showed plants colonized at the heavy contaminated sites in XKS had great tolerance to As, Sb, and Bi, and demonstrated similarities in plant uptake and accumulation of these three elements.     

Bacteria of the sulfur cycle in the sediments of gold mine tailings,Kuznetsk Basin,Russia

The number and diversity of culturable microorganisms involved in sulfur oxidation and sulfate reduction were investigated in the oxidized sediments of gold mine tailings, Kuznetsk Basin, Russia. The sediments had a low pH (2.4–2.8), high SO ₄ ^2? content (up to 22 g/l), and high concentrations of dissolved metals. The arsenic content was as high as 1.9 g/l. Bacterial phylogeny in microcosms was investigated by amplification of 16S rRNA gene fragments with subsequent denaturing gradient gel electrophoresis (DGGE). Spore-forming bacteria Desulfosporosinus were the only bacteria revealed for which the capacity for dissimilatory sulfate reduction is known. Strain Desulfosporosinus sp. DB was obtained in pure culture, and it was phylogenetically remote from other cultured and uncultured members of the genus. No sulfate-reducing members of the Deltaproteobacteria were detected. The Firmicutes members were the most numerous phylotypes in the microcosms, including a separate cluster with the similarity to Pelotomaculum not exceeding 94%. Acidithiobacillus ferrooxidans and A. caldus were found in anaerobic and microaerophilic microcosms. The number of sulfate reducers did not exceed 9.5 × 10² cells/ml.     

Plant response to biochar,compost, and mycorrhizal fungal amendments in post‐mine sandpits

Extreme growing conditions inhibit restoration in sandpit mines. Co‐amendment of soil conditioners such as biochar, compost, and arbuscular mycorrhizal fungi (AMF) may alleviate these stresses and lead to a more successful restoration. We conducted a multiyear restoration experiment in a sandpit in Southern Ontario, Canada, following industrial‐scale grassland restoration protocols. The sandpit substrate was sand with low carbon (C) and nutrients. We tested the effect of biochar, compost, and AMF inoculum in two experiments (plant plugs vs. seed application). In the plant plug trial, we investigated the treatment effects on the growth of eight grassland plant species and colonization of plant roots by AMF over two growing seasons. We found that co‐amending soils with compost plus biochar (20 T/ha + 10 T/ha) was more beneficial than other amendment combinations. Amendments including AMF were not more beneficial to plant growth than those without AMF. In the seed application trial, direct inoculation of AMF in the field combined with high compost addition (20 T/ha or 40 T/ha) resulted in the highest plant cover compared to other treatment combinations. Our results indicate that co‐amending sandpit substrates with biochar, compost, and AMF are practical restoration tools that enhance grassland restoration.