Sulfate-reducing bacterial community shifts in response to acid mine drainage in the sediment of the Hengshi watershed,South China

Environmental Science and Pollution Research - Sulfate-reducing bacteria (SRB) are an attractive option for treating acid mine drainage (AMD) and are considered to be of great significance in the...     

Immobilization of lead and cadmium from aqueous solution and contaminated sediment using nano-hydroxyapatite

The effectiveness and mechanism of nano-hydroxyapatite particles (nHAp) in immobilizing Pb and Cd from aqueous solutions and contaminated sediment were investigated. The maximum sorption amount (Q_max) of Pb and Cd in aqueous solution was 1.17 and 0.57 mmol/g. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) surface and depth analysis indicated that dissolution-precipitation is the primary immobilization mechanism for Pb, while surface complexation and intraparticle diffusion account for Cd sequestration. Different amounts of nHAp (0-10% nHAp/dry weight) were added to the contaminated sediment. Sequential extraction showed that nHAp could effectively reduce the exchangeable fraction of Pb and Cd in the sediment and significantly reduce the concentration in porewater. The results in this study showed that nHAp can immobilize Pb and Cd in sediment effectively.     

有氧垂直折流式反应池处理煤矿酸性废水

为了使实验研究成果更好应用于工程实际,在野外建立了一套有氧垂直折流式反应池来处理贵阳市久安乡废弃煤窑产生的煤矿酸性废水.工程实验研究显示,在有氧垂直折流式反应池中,进水pH值可由2.45～2.95提高到5.91～7.76,单位面积铁的平均去除速率为44.63 g/(d·m2),反应池中铝、铜的去除率均分别在98.44%...     

Removal of nickel from neutral mine drainage using peat-calcite,compost, and wood ash in column reactors

Environmental Science and Pollution Research - The effectiveness of compost, peat-calcite, and wood ash to remove Ni from a circum-neutral-contaminated mine water was tested in continuous flow...     

Characterization of iron-metabolizing communities in soils contaminated by acid mine drainage from an abandoned coal mine in Southwest China

Environmental Science and Pollution Research - Acid mine discharge (AMD) has been demonstrated to have significant impacts on microbial community composition in the surrounding soil environment....     

西北黄土地区现场石油污染土壤生物修复研究

通过在陕北安塞油田某废弃油井建立中试试验基地,以实验室中筛选分离得到的高效降解石油的优势菌为添加的高效菌,研究土壤石油初始浓度、营养物质和高效菌对石油降解的影响.结果表明:(1)在各土壤石油初始浓度下,石油降解率总体均随降解时间的延长而升高.在土壤石油初始质量浓度为15.34 g/kg下,72 d时石油降解率为47.8...     

Multi-element analysis of road-deposited sediment in an urban drainage basin, Honolulu, Hawaii

Road-deposited sediment (RDS) and its associated contaminant load play a critical role in degrading receiving water bodies. Few quantitative multi-element RDS studies exist, and there are none from Hawaii. This lack of baseline data combined with concerns with high concentrations of Pb and Cu in fish and enrichment of Cu, Pb and Zn in bed sediments from Manoa Stream, Hawaii, lead to a detailed characterization of RDSs in Manoa basin. Data for a total analysis of 23 elements using inductively coupled plasma atomic-emission spectrometry and instrumental neutron activation analysis and 16 elements using a 0.5 M HCl partial leach are presented for RDSs and background soils. Concentration data, comparisons with environmental guidelines, and concentration enrichment ratios (CERs) all indicate that RDS in Manoa has a significant degree of anthropogenic pollution. The most environmentally important elements were Pb, Sb and Zn. Concentrations of these elements, primarily vehicle contributed, compare favorably with those from other studies of RDS. The high mean concentration of Pb (151 mg/kg) compared to background soils (13 mg/kg) indicates remobilization of Pb previously stored in soils and transported to road surfaces by water erosion processes. The higher Pb CER(Total) in RDSs compared to bed sediments from Manoa Stream suggests a potential link via ubiquitous storm drains and subsequent dilution with less contaminated fluvial sediments. Data from the HCl leach also support Pb and Zn as having significant anthropogenic signals, and Cu having a moderate signal. These data indicate that RDSs in Manoa basin are generally contaminated with certain potentially toxic elements and the legacy of past use of leaded gasoline is still a concern in this urban drainage system.     

Assessment of polybrominated diphenyl ethers in sediment of Asunle stream of the Obafemi Awolowo University,Ile-Ife,Nigeria

Assessment of levels of polybrominated diphenyl ethers (PBDEs) from the sediment of Asunle stream, an adjourning stream of the Obafemi Awolowo University dumpsite, has been carried out. Sediment samples were collected from the stream at six locations for a period of 8 months, composed of 4 months each of wet (May–Aug) and dry (Nov–Feb) seasons. Soxhlet extraction was employed for the isolation of all the target compounds from the sediment samples. Extracts were further subjected to multi-layer column chromatography employing different forms of silica gel. The prepared samples were analyzed using GC-MS. The overall mean concentrations of the total PBDEs ranged from 1.80 to 9.46 ng/g. The results showed that the concentrations of the PBDEs were slightly higher during the wet season than those during the dry season. In all the studied locations, BDE28, BDE47, BDE99, BDE100, BDE153, and BDE154 were detected in all the sediment samples at concentrations that ranged from 0.73 to 10.43 ng/g. Results of this study indicated that BDE153 was the major pollutant of the Asunle stream sediments.     

Geochemical characteristics of dissolved rare earth elements in acid mine drainage from abandoned high-As coal mining area,southwestern China

Acid mine drainage (AMD) represents a major source of water pollution in the small watershed of Xingren coalfield in southwestern Guizhou Province. A detailed geochemical study was performed to investigate the origin, distribution, and migration of REEs by determining the concentrations of REEs and major solutes in AMD samples, concentrations of REEs in coal, bedrocks, and sediment samples, and modeling REEs aqueous species. The results highlighted that all water samples collected in the mining area are identified as low pH, high concentrations of Fe, Al, SO₄ ^2? and distinctive As and REEs. The spatial distributions of REEs showed a peak in where it is nearby the location of discharging of AMD, and then decrease significantly with distance away from the mining areas. Lots of labile REEs have an origin of coal and bedrocks, whereas the acid produced by the oxidation of pyrite is a prerequisite to cause the dissolution of coal and bedrocks, and then promoting REEs release in AMD. The North American Shale Composite (NASC)-normalized REE patterns of coal and bedrocks are enriched in light REEs (LREEs) and middle REEs (MREEs) relative to heavy REEs (HREEs). Contrary to these solid samples, AMD samples showed slightly enrichment of MREEs compared with LREEs and HREEs. This behavior implied that REEs probably fractionate during acid leaching, dissolution of bedrocks, and subsequent transport, so that the MREEs is primarily enriched in AMD samples. Calculation of REEs inorganic species for AMD demonstrated that sulfate complexes (Ln(SO₄)⁺and Ln(SO₄)₂ ^?) predominate in these species, accounting for most of proportions for the total REEs species. The high concentrations of dissolved SO₄ ^2? and low pH play a decisive role in controlling the presence of REEs in AMD, as these conditions are necessary for formation of stable REEs-sulfate complexes in current study. The migration and transportation of REEs in AMD are more likely constrained by adsorption and co-precipitation of Fe-Al hydroxides/hydroxysulfate. In addition, the MREEs is preferentially captured by poorly crystalline Fe-Al hydroxides/hydroxysulfate, which favors that sediments also preserve NASC-normalized patterns with MREEs enrichment in the stream.

     

Selenium volatilization in vegetated agricultural drainage sediment from the San Luis Drain, Central California

The presence of large amounts of Se-laden agricultural drainage sediment in the San Luis Drain, Central California, poses a serious toxic threat to wildlife in the surrounding environment. Effective management of the drainage sediment becomes a practical challenge because the sediment is polluted with high levels of Se, B, and salts. This two-year field study was conducted to identify the best plant species that are salt and B tolerant and that have a superior ability of volatilizing Se from drainage sediment. The drainage sediment was mixed with clean soil, and vegetated with salado alfalfa (Medicago sativa 'salado'), salado grass (Sporobulus airoides 'salado'), saltgrass-turf (Distichlis spp. 'NYPA Turf'), saltgrass-forage (Distichlis spicata (L.) Greene), cordgrass (Spartina patens 'Flageo'), Leucaenia (Leucaena leucocephola), elephant grass (Pennistum purpureum), or wild type-Brassica (Brassica spp.). Results show that elephant grass produced the greatest amount of biomass and accumulated highest concentrations of B. Highest concentrations of Se, S, and Cl were observed in wild-type Brassica. Biogenic volatilization of Se by plants and soil microbes was greater in summer. Among the treatments, the mean daily rates of Se volatilization (microg Se m(-2)d(-1)) were wild-type Brassica (39) > saltgrass-turf (31) > cordgrass (27) > saltgrass forage (24) > elephant grass (22) > salado grass (21) > leucaenia (19) > salado alfalfa (14) > irrigated bare soil (11) > non-irrigated bare soil (6). Overall, rates of Se volatilization in drainage sediment were relatively low due to high levels of sulfate. To manage Se in drainage sediment by phytoremediation, the biological volatilization process needs to be enhanced substantially under field conditions.     

Metal transport in a stream polluted by acid mine drainage--The Afon Goch, Anglesey, UK

Sampling of the Afon Goch over a 14-month period revealed maximum dissolved Fe, Al, Mn, Cu and Zn concentrations of 259, 167, 49, 60 and 42 mg dm(-3), respectively, and pH as low as 2.3, making it one of the most metal- and acid-contaminated streams in the UK. The river produces particulates by precipitation of ferrihydrite, due to the entry of near-neutral tributary waters, under all discharge conditions. Consequently, metal transport in this stream is dominated by processes different from those in less contaminated streams. The stream acts as a sink for contaminants, except under high discharge, when accumulated metals are flushed from the system. The implications of these observations for the monitoring and management of streams polluted by acid mine drainage are discussed.     

Neutralization/prevention of acid rock drainage using mixtures of alkaline by-products and sulfidic mine wastes

Backfilling of open pit with sulfidic waste rock followed by inundation is a common method for reducing sulfide oxidation after mine closure. This approach can be complemented by mixing the waste rock with alkaline materials from pulp and steel mills to increase the system’s neutralization potential. Leachates from 1 m³ tanks containing sulfide-rich (ca.30 wt %) waste rock formed under dry and water saturated conditions under laboratory conditions were characterized and compared to those formed from mixtures. The waste rock leachate produced an acidic leachate (pH?<?2) with high concentrations of As (65 mg/L), Cu (6 mg/L), and Zn (150 mg/L) after 258 days. The leachate from water-saturated waste rock had lower concentrations of As and Cu (<2 μg/L), Pb and Zn (20 μg/L and 5 mg/L), respectively, and its pH was around 6. Crushed (<6 mm) waste rock mixed with different fractions (1–5 wt %) of green liquid dregs, fly ash, mesa lime, and argon oxygen decarburization (AOD) slag was leached on a small scale for 65 day, and showed near-neutral pH values, except for mixtures of waste rock with AOD slag and fly ash (5 % w/w) which were more basic (pH?>?9). The decrease of elemental concentration in the leachate was most pronounced for Pb and Zn, while Al and S were relatively high. Overall, the results obtained were promising and suggest that alkaline by-products could be useful additives for minimizing ARD formation.     

Heavy metals in water, sediment and tissues of Leuciscus cephalus from a stream in southwestern Turkey

Concentrations of heavy metals (Cd, Cr, Cu, Pb and Zn) were measured in water, bottom sediment and tissues (muscle and gills) of Leuciscus cephalus from the Dipsiz stream in the Yatagan basin (southwestern Turkey), the site of a thermal power plant. Results for levels in water were compared with national and international water quality guidelines, as well as literature values were reported for streams and rivers. Comparisons were made of metal concentrations in water and sediment with those in the muscle and gills of L. cephalus caught from the Dipsiz stream. We found that there was metal accumulation in the gills compared to the muscle. Concentrations of Cd, Pb, Zn and Cr in the gills were higher than that in the muscle; however, Cu levels were higher in muscle than that in gills. Concentrations of heavy metals in L. cephalus muscle were below the legal limits for human consumption, although Cr, Pb and Zn levels in the gills were above the limits in the fish taken from the Dipsiz stream. On the other hand, no correlation was found between metal concentrations in water and sediment or between metal concentrations in water and muscle and gills of L. cephalus. A positive correlation was found between concentrations of Cu and Zn in the sediment and in fish tissue, whereas there was no relationship between other metal concentrations in the sediment and water, and muscle and gills of L. cephalus. As with water, Pb and Cd concentrations in particular were higher in sediment than that in background levels. The results show that the pollutants from the thermal power plant may be a source of these elements.     

Toxicity of copper in an oxic stream sediment receiving aquaculture effluent.

Sediments were collected from a stream (upstream, outfall and downstream) receiving copper laden catfish pond effluent to assess toxicity to non-target biota. No significant reduction in Hyalella azteca survival or growth (10 d), or Typha latifolia germination and root and shoot growth (7 d) were observed after exposure to upstream and outfall sediments. A significant reduction in H. azteca survival was observed after exposure to the downstream sediment sample; however, no reduction in T. latifolia germination or seedling growth was detected. Bulk sediment copper concentrations in the upstream, outfall and downstream samples were 29, 31, and 25 mg Cu/kg dry weight, respectively. Interstitial water (IW) concentrations ranged from 0.053 to 0.14 mg Cu/l with 10 d IW toxicity units > or = 0.7. Outfall samples were amended with additional concentrations of copper sulfate so that bulk sediment measured concentrations in the amended samples were 172, 663, 1245, and 1515 mg Cu/kg dry weight. Survival was the most sensitive endpoint examined with respect to H. azteca with a no observed effects concentration (NOEC) and lowest observed effects concentration (LOEC) of 1245 and 1515 mg Cu/kg, respectively. NOEC and LOEC for T. latifolia root growth were 663 and 1245 mg Cu/kg, respectively. IW copper concentrations were > or = 0.86 mg Cu/l with H. azteca intersitial water toxicity unit (IWTU) concentrations > or = 1.2. Sequential extraction qualitatively revealed the carbonate and iron oxide fractions which accounted for a majority of the copper binding. In this instance, the copper which was applied to catfish ponds does not appear to be adversely impacting the receiving stream system.     

基于氧化还原-分步沉淀法的酸性矿山废水处理效果

为降低韶关市大宝山酸性矿山废水(AMD)的处理成本,采用氧化还原-分步沉淀法对矿山废水进行处理。结果表明：将石灰石分多次投入经过还原处理的废水中,在反应时间为45 min、转速为250 r·min⁻¹、废水pH为5时,可从AMD中回收高品质石膏;继续用NaOH溶液调节废水pH至5.5,控制曝气量为4 mg·L⁻¹,曝气时间为45 min,通过氧化沉淀法和铁氧体法可分步回收废水中的Fe^2+/3+,再向废水中加入NaOH溶液,调节废水pH至9.5,可沉淀回收废水中的Zn²⁺、Cu²⁺;经过该工艺处理后,废水中各金属离子均低于国家污水综合排放标准(GB 8978-1996);该工艺处理1 t废水,可回收石膏5.4 kg(纯度85.72%),铁渣1.53 kg(w(Fe)=35.4%)、锌铜渣1.4 kg(w(Zn)=10.89%、w(Cu)=0.1%);废水中Fe^2+/3+、Zn²⁺、Cu²⁺回收率分别为84.3%、71.2%、46.2%,废水处理的药剂成本为4.1元·t⁻¹,废水产生可回收资源产品收入为3.8 元·t⁻¹。该工艺可从AMD中回收高品质石膏并分步回收废水中的金属,有效降低废水的处理成本,回收废水中的资源,实现环保与经济效益双赢的目标,并为AMD资源化处理提供理论指导。     

A sediment diagenesis model on sediment oxygen demand in managing eutrophication on Taihu,China

Environmental Science and Pollution Research - Blue-green algae (CyanoHABs), photosynthetic bacteria that create a harmful aquatic environment, have been a trending issue on Taihu for over a...     

SDS促进复配酶水解排水管网沉积物

采用SDS协同复配酶水解排水管网沉积物,分别考察了SDS投加量、反应时间、pH、温度4个影响因素对沉积物水解效果的影响,并通过 SEM、EPS、三维荧光光谱以及粒径等表征方法进行机理分析。结果表明,投加5%(w:w)SDS与8%(w:w)复配酶,在原泥pH(7.28±0.3)、25 ℃、反应时间为2 h时,沉积物水解效果最好。此时SCOD、多糖和氨氮分别由初始的5 686.9、1 913.75和87.32 mg·L⁻¹增加到8 192.9、3 561.29和153.37 mg·L⁻¹,有机质含量由56.32%下降到55.59%。在SDS+复配酶处理管网沉积物后,其内部紧实结构被破坏,TB-EPS向S-EPS转移,腐殖酸类物质荧光强度增强,表明溶解性EPS增多,且沉积物粒径向<300 μm转变。高通量测序分析结果表明,SDS+复配酶对管网沉积物微生物种类的丰富度和多样性影响不大,但在一定程度上会改变微生物的功能菌群,减少CH₄和H₂S的产生。以上研究结果可为延缓排水管网淤堵问题提供数据支持。     

Acid mine drainage arising from gold mining activity in Johannesburg,South Africa and environs

The Witwatersrand region of South Africa is famous for its gold production and a major conurbation, centred on Johannesburg, has developed as a result of mining activity. A study was undertaken of surface and ground water in a drainage system in this area. Soils were also analysed from a site within the mining district. This study revealed that the ground water within the mining district is heavily contaminated and acidified as a result of oxidation of pyrite (FeS2) contained within mine tailings dumps, and has elevated concentrations of heavy metals. Where the water table is close to surface, the upper 20 cm of soil profiles are severely contaminated by heavy metals due to capillary rise and evaporation of the ground water. The polluted ground water is discharging into streams in the area and contributes up to 20% of stream discharge, causing a lowering of pH of the stream water. Much of the metal load is precipitated in the stream: Fe and Mn precipitate as a consequence of oxidation, while other heavy metals are being removed by co-precipitation. The oxidation of iron has created a redox buffer which controls the pH of the stream water. The rate of oxidation and of dilution is slow and the deleterious effect of the addition of contaminated water persists for more than 10 km beyond the source.     

Distribution and persistence of aminocarb in stream water, sediment and fish after application of three Matacil formulations

Three aminocarb formulations, water-based Matacil 180F, oil-based Matacil 180F and oil-based Matacil 180D, were applied separately to the surface of a stream at 2.40 g a.i./min for 5 minutes. The highest aminocarb concentration in the top 1 cm of water was found 5 min after application of oil-based 180F (5000 ppb). The next highest concentration was 1862 ppb found in the top 1 cm layer of water 3 min after application of oil-based 180D, followed by 1306 ppb found 5 min after application of water-based 180F. Residue accumulations were first observed in sediment at 3 min and in fish tissues 0.5 h after application. The levels of accumulation were in the order of water-based 180F greater than oil-based 180F greater than oil-based 180-D. After the application of water-based 180F, the highest concentrations were 20.2 ppb in sediment after 5 min and 127 ppb in fish tissues after 3 h. Residues disappeared rapidly from all three matrices and could not be detected after a period of 3-25 h.