Layered structure of granules in upflow anaerobic sludge blanket reactor gives microbial populations resistance to metal ions

Metal ions (Cd²⁺, Cu²⁺, Ni²⁺, Zn²⁺ and Cr³⁺) did not affect glucose degradation or the production of methane during anaerobic digestion with intact and disintegrated granules from a UASB (Upflow Anaerobic Sludge Blanket) reactor. However, when Cu²⁺ was at 500 mg g^–1 VSS (volatile suspended solids) in the media, the glucose degradation rates and methane production rates decreased by 14% and 32% in disintegrated granules, respectively, whereas, in intact granules, decreases were 3% and 14%, respectively. When various electroplating metal ions were tested, 50% inhibition of acetate degradation and methane production were produced by 210–770 mg g^–1 VSS and 120–630 mg g^–1 VSS, respectively. The relative toxicity of the electroplating metals on methane production was in the order of Zn²⁺ (most toxic) > Ni²⁺ > Cu²⁺ > Cr³⁺ > Cd²⁺ (least toxic).     

Concentration and annual accumulation values of heavy metals in lake sediments: Their significance in studies of the history of heavy metal pollution

The first part of the paper discusses the significance of using either concentration or accumulation values for expressing the results of investigations of lake sediment cores aimed at studying the history of heavy metal pollution. Neither the values for heavy metal concentration in the lake sediment, whether expressed per gram dry sediment or per gram soluble (organic) sediment, nor the values for their total annual accumulation per unit area of the lake bottom, can, on their own, provide an accurate picture of past pollution conditions, but when considered in combination they render a fairly reliable and detailed interpretation. The second part of the paper deals with Pb, Cd and Hg analyses of cores of varved sediments from several lakes in N. Sweden. Pb and Cd pollution increased during the second half of the 19th century. In most lakes, Hg pollution seems first to have started during the 20th century. Marked increases in both concentration and accumulation of heavy metals took place during the 20th century. For recent decades, the estimated accumulation rates of heavy metals from anthropogenic sources are: Pb 0.5–1.5 µg cm^–2 yr^–1, Cd 15–30 ng cm^–2 yr^–1 and Hg 1–2 ng cm^–2 yr^–1, Higher values were recorded in lakes affected by local emissions.     

公路绿化带对路旁土壤重金属污染格局的影响及防护效应——以山西省主要公路为例

在山西省典型公路绿化路段路侧设置样带,在样带内按距离梯度采集路旁土壤并进行Pb、Cr、Cu、Zn重金属含量测定,采用污染指数分析4种重金属污染物的扩散格局及公路绿化带的影响,比较不同结构特征的绿化带对4种重金属污染防护效应的差异。结果表明,4种土壤重金属污染扩散格局呈单峰态,主要污染区间出现在10—70m范围内,4种重金属污染指数峰值与峰值位置不同;公路绿化带对土壤4种重金属污染有显著防护效应,可将污染限制在50m范围内,使峰值高度降低,峰值位置提前;绿化带宽度、郁闭度和树种组成对林带防护效应有显著影响,绿化带宽度在40—70m即可保证对路旁土壤重金属污染起到有效防护作用,单树种绿化带郁闭度≥0.6,可缩小重金属主要污染区间,100m处污染指数降为0.139—0.977;栽植混交林带使其成林后郁闭度≥0.6,对路旁土壤的重金属污染效果更好,可将重金属污染的峰值位置限制在20m范围内。     

Effects of some metal ions on rainbow trout erythrocytes glutathione S-transferase enzyme: an in vitro study

Glutathione S-transferase enzyme (GST) (EC 2.5.1.18) was purified from rainbow trout erythrocytes, and some characteristics of the enzyme and effects of some metal ions on enzyme activity were investigated. For this purpose, erythrocyte glutathione S-transferase enzyme which has 16.54 EU/mg protein specific activities was purified 11,026-fold by glutathione-agarose affinity chromatography with a yield of 59%. Temperature was kept under control (+4°C) during purification. Enzyme purification was checked by performing SDS-PAGE. Optimal pH, stable pH, optimal temperature, and K_M and V_max values for GSH and 1-chloro-2, 4-dinitrobenzene (CDNB) were also determined for the enzyme. In addition, IC₅₀ values, K_i constants and the type of inhibition were determined by means of Line-Weaver-Burk graphs obtained for such inhibitors as Ag⁺; Cd²⁺, Cr²⁺ and Mg²⁺.     

The current status of heavy metal in lake sediments from China: Pollution and ecological risk assessment

Heavy metal contamination in lake sediments is a serious problem, particularly in developing countries such as China. To evaluate heavy metal pollution and risk of contamination in lake sediments on a national scale in China, we collated available data in the literature of the last 10 years on lake sediments polluted with heavy metals from 24 provinces in China. Based on these data, we used sediment quality guidelines, geoaccumulation index, and potential ecological risk index to assess potential ecological risk levels. The results showed that approximately 20.6% of the lakes studied exceeded grade II level in Chinese soil quality standards for As, 31.3% for Cd, 4.6% for Cu, 20.8% for Ni, 2.8% for Zn, and 11.1% for Hg, respectively. Besides, the mean concentrations for As in 10.3% of lakes, Hg in 11.9% of lakes, and Ni in 31.3% of lakes surpassed the probable effect level. The potential ecological risk for toxic metals decreased in the order of Cd > Hg > As > Cu > Pb > Ni > Cr > Zn, and there were 21.8% of the lakes studied in the state of moderate risk, 10.9% in high risk, and 12.7% in very high risk. It can be concluded that Chinese lake sediments are polluted by heavy metals to varying degrees. In order to provide key management targets for relevant administrative agencies, based on the results of the pollution and ecological risk assessments, Cd, Hg, As, Cu, and Ni were selected as the priority control heavy metals, and the eastern coastal provinces and Hunan province were selected as the priority control provinces. This article, therefore, provides a comprehensive assessment of heavy metal pollution in lake sediments in China, while providing a reference for the development of lake sediment quality standards.     

桂北典型锰矿区周边土壤重金属污染状况及主要植物富集特征

为探究桂北某典型锰矿尾库区周边土壤和农作物重金属污染状况,筛选适合该地区污染土壤修复的植物材料,该研究在矿区周边采集了9种农作物和23种主要植物及其根际土壤,并测定了Cd、Mn、Cr、Pb和Zn 5种重金属含量,采用单因子污染指数法和综合污染指数法评价了矿区农田土壤、农作物中重金属的生态风险,通过计算植物对重金属的富集和转运系数评估其应用潜力。结果表明:(1)研究区土壤Cd、Mn污染最为严重,单因子污染指数分别为18.53、147.09,达到重度污染级别。(2)研究区花生和小白菜等作物可食用部位中的Cd、Cr、Pb含量均超过食品国家安全标准(GB 2762—2017)中的阈值,具有较高健康风险。(3)23种主要植物中青葙、鬼针草、一点红、蜈蚣草等对多种重金属转运系数大于1,具备富集型植物特征; 一把伞南星、蓖麻、千里光等根部重金属含量较高,转运系数较低,具备根部囤积型植物特征; 响铃豆、筒轴茅、苣荬菜等富集的重金属含量相对较低,且在重金属污染土壤中能健康生长,具备规避型植物特征。该研究结果表明,研究区土壤存在较严重的Cd/Mn复合污染,青葙等植物用于修复该复合污染土壤极具应用潜力。     

Influence of zinc ions on protein secretion in a heavy metal tolerant strain of the ericoid mycorrhizal fungas Oidiodendron maius

A heavy metal tolerant strain of the ericoid mycorrhizal species Oidiodendron maius, isolated from soil heavily contaminated with zinc, was previously shown to tolerate high concentrations of zinc and cadmium ions in the growth medium. We have investigated some of the specific molecular responses of this fungal strain to the presence of increasing concentrations of zinc ions in the growth medium. In particular, we show that zinc ions induce a general change in the array of secreted proteins, with a shift towards the production of more basic, low molecular weight polypeptides. Some of these proteins were microsequenced and identified through homology search in databases. Among them are hydrolytic enzymes (nuclease, proteinase, lysozyme) and two superoxide dismutase isoforms. The latter are antioxidant enzymes known to play a role in heavy metal response in plants, animals and microorganisms.     

植物重金属转运蛋白P_(1B)-ATPase结构和功能研究进展

植物调节体内重金属的累积量以维持自身生存,其中,金属阳离子转运蛋白发挥了关键作用。P1B-ATPase是在生物中广泛存在的P-ATPase中的一个亚族,也是P-ATPase多个亚族中唯一参与重金属稳态的转运蛋白。拟南芥中共发现8个P1B-ATPase。研究表明,P1B-ATPase在植物体内具有维持金属的稳态、转运以及金属解毒的功能;与金属离子在根部区域的活化、吸收、地上部分的运输、贮存,以及植物对重金属的耐受性均相关。以下综述了P1B-ATPase的进化分类、结构特征以及功能方面的最新研究进展,并展望了其在植物修复领域的应用前景。     

重金属超富集植物及植物修复技术研究进展

植物修复技术（Phytoremediation)是近年来发展起来的一种主要用于清除土壤重金属污染的绿色生态技术,重金属超富集植物（hyperaccumulator)及植物修复技术是当前学术界研究的热点领域,目前虽已有Cd、Co、Cr、Cu、Mn、Ni、Pb、Zn等超富集植物发现的报道,但尚无一例报道来自于中国,中国具有广袤的国土面积、丰富的植物类型和多种（处）古老的矿山开采与冶炼场所,在中国开展超富集植物的寻找,研究与开发工作,将会有重要突破,并具有重要的理论与实践意义,本文拟就国内外在这一领域的研究进展作一简要综述。     

Estimation of the mean distance of closest approach of some heavy metal ions in aqueous solutions: some experimental and theoretical calculations

The estimation of numerical values of the mean distance of closest approach of ions, a, of heavy metal ion salts in aqueous solutions, determined from activity coefficients, as well as from different theoretical approaches, is presented and discussed.     

Study of fluorescence quenching of mercaptosuccinic acid‐capped CdS quantum dots in the presence of some heavy metal ions and its application to Hg(II) ion determination

In this study, CdS quantum dots (QDs) capped with mercaptosuccinic acid (MSA) were prepared in one step. The size, shape, component and spectral properties of MSA‐capped CdS QDs were characterized by transmission electron microscopy (TEM), photoluminescence (PL) and infrared (IR) spectrometry. The results showed that the prepared QDs with an average diameter of 6 nm have favorable fluorescence, which is greatly influenced by the pH of the environment. The interaction of some heavy metal ions including Ag⁺, Hg²⁺, Cu²⁺, Ni²⁺ and Co²⁺ with MSA‐capped CdS QDs was investigated in different buffering pH media. Based on the fluorescence quenching of the QDs in the presence of each of the metal ions, the feasibility of their determinations was examined according to the Stern–Volmer equation. The investigations showed that Hg(II) ions can be determined in the presence of many co‐existing metal ions at a buffering pH of 5. This method was satisfactorily applied to the measurement of Hg(II) ions in some environmental samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Distribution and health risk assessment of heavy metals in soil surrounding a lead and zinc smelting plant in Zanjan,Iran

One of the problematic issues in soil pollution studies is heavy metal particles which are produced by mines and smelting units and spread through wind action and/or runoff. Pollution and health risk assessment of cadmium, lead, zinc, copper, and nickel in soil around the lead and zinc smelting factory was carried out in Zanjan City, Iran. Contamination factor (Cf), pollution load index (PLI), geoaccumulation index (Igeo), hazard quotient (HQ), hazard index (HI), and carcinogenic risk were pollution and human health risk assessment metrics in this study. Based on the Iranian soil guideline value, soil samples in the studied areas were contaminated the least by copper and nickel and the most by cadmium. PLI results showed that soils near the production line were heavily or extremely heavily polluted. The results of Cf and Igeo showed that lead and zinc were the most important contaminants. Health risk assessment indicated that lead and cadmium in soil were the main contaminants, which pose both carcinogenic and non-carcinogenic risks to human health; carcinogenic risk levels were unacceptably high (above 1 × 10^?4). It can be concluded that mining and smelting activities degrade soil quality in this region and the soil pollution might be extended to farming areas.     

畜禽养殖废物中抗生素和重金属抗性基因的产生机制和控制方法研究进展

动物饲料中常混有抗生素和重金属,导致外排的动物粪便中携带有抗生素和重金属,引发细菌产生耐药性和重金属抗性,继而产生抗生素抗性基因和重金属抗性基因。抗生素和重金属抗性基因污染已成为威胁人类身体健康及破坏生态环境的重大问题。本文从细菌进化的角度,明确了细菌的抗生素和重金属长期进化试验对抗性机制研究的重要性;抗生素抗性基因与重金属抗性基因间存在复杂的协同选择抗性,两者间相互影响,共同决定着细菌环境行为;抗性基因的水平转移增加了细菌在环境中的可变性,可移动遗传元件在抗性基因水平转移中发挥着重要作用。在抗性基因污染控制方面,高级氧化技术具有很好的抗性基因去除效果,尤其是UV/TiO₂氧化技术,能使抗生素抗性基因丰度减少4.7～5.8 log,减少率大于99.99%。其他的控制策略,如抗生素替代品博落回提取物以及噬菌体与抗生素结合使用,对于抗性基因的控制也具有重要意义。     

Constructed wetlands for waste water treatment: the use of laterite in the bed medium in phosphorus and heavy metal removal

In Northern Ireland, phosphorus enrichment of lakes due to agriculture is a significant problem. Heavy metal exports from landfill sites, often located on water-logged land, are also of concern. Locally available laterite, a low grade bauxite which is rich in iron and aluminium, is used in acid solution with subsequent precipitation to remove phosphorus and heavy metals at several sewage treatment works. Constructed wetlands offer an attractive alternative to conventional waste water treatment in certain circumstances but removal of phosphorus is strongly dependent on the bed medium. Calcium-, iron- and aluminium-rich solid media are recommended. A brief introduction to the use and cost-effectiveness of constructed wetlands (CWs) in treating a range of effluents is given. This study, using both laboratory tests and pilot-scale constructed wetlands, reports the effectiveness of granular laterite in removing phosphorus and heavy metals from landfill leachate. Initial laboratory studies have shown that laterite is capable of 99% removal of phosphorus from solution. A pilot-scale experimental CW containing laterite achieved 96% removal of phosphorus. This removal is much greater than that reported in other systems. Initial removals of aluminium and iron by pilot-scale CWs have been up to 85% and 98% respectively. Percolating columns of laterite reduced Cd, Cr and Pb to undetectable concentrations. Possible application of this low cost, low technology, visually unobtrusive yet efficient system to rural areas with dispersed point sources of pollution is discussed.     

Mutagenicity (micronucleus test in Vicia faba root tips), polycyclic aromatic hydrocarbons and heavy metal content of sediments collected in Tiber river and its tributaries within the urban area of Rome

Sediments collected in Tiber river and in its main tributary water courses within the urban area of Rome were tested for mutagenicity by means of Vicia faba root tips micronucleus (MN) test. Representative samples were scored for micronucleus generating events (chromosome/chromatid loss and fragments) too. Sediments were assayed for content of the thirteen most important chemicals of polycyclic aromatic hydrocarbon (PAH) group and for some heavy metal ions (Cd, Cr, Cu, Ni, Pb, Zn). Samples were collected in four tributary rivers (Prima Porta, Acqua Traversa, Aniene and Magliana) just before their confluence with Tiber river and at different stations along the Tiber river itself upstream and downstream the sites of confluence of the sampled tributaries. All samples were collected in July 1992. An alarming level of mutagenicity was reached in most of the tested stations, with an effect comparable to an X-rays exposure up to 0.4 Gy. Chemical analysis showed that the total amount of identified PAHs ranged from 4.5 to 625.2 ng/g of dry matrix in the different stations and the total amount of heavy metals ranged from 130 to 570 ppm. Tiber mutagenicity is likely to be mainly due to local factors such as the confluence of a small polluted tributary rather than to large scale effect due to an upstream–downstream relationship.     

An amperometric biosensor based on horseradish peroxidase immobilized onto maize tassel-multi-walled carbon nanotubes modified glassy carbon electrode for determination of heavy metal ions in aqueous solution

A biosensor for trace metal ions based on horseradish peroxidase (HRP) immobilized on maize tassel-multiwalled carbon nanotube (MT-MWCNT) through electrostatic interactions is described herein. The biosensor was characterized using Fourier transform infrared (FTIR), UV–vis spectrometry, voltammetric and amperometric methods. The FTIR and UV–vis results inferred that HRP was not denatured during its immobilization on MT-MWCNT composite. The biosensing principle was based on the determination of the cathodic responses of the immobilized HRP to H₂O₂, before and after incubation in trace metal standard solutions. Under optimum conditions, the inhibition rates of trace metals were proportional to their concentrations in the range of 0.092–0.55 mg L⁻¹, 0.068–2 mg L⁻¹ for Pb²⁺ and Cu²⁺ respectively. The limits of detection were 2.5 μg L⁻¹ for Pb²⁺ and 4.2 μg L⁻¹ for Cu²⁺. Representative Dixon and Cornish-Bowden plots were used to deduce the mode of inhibition induced by the trace metal ions. The inhibition was reversible and mixed for both metal ions. Furthermore, the biosensor showed good stability, selectivity, repeatability and reproducibility.     

Evaluation of metal contamination and risk assessment to human health in a coal mine region of India: A case study of the North Karanpura coalfield

The present study aimed to evaluate metal contamination level in coal mine water of the North Karanpura coalfields and assess the possible health risk due to the intake of untreated mine water. Fourteen coal mine water samples were collected from the study area and analyzed for Al, As, Ba, Cr, Cu, Fe, Mn, Ni, Se, and Zn using inductively coupled plasma-mass spectroscopy (ICP-MS). The heavy metal pollution index (HPI) was used to calculate metal pollution level in the coal mine water. The hazard quotient (HQ) and hazard index (HI) were estimated for health risk to child and adult by using the United States Environmental Protection Agency (USEPA) methods. The concentrations of Al, Fe, Mn, and Ni in coal mine water were exceeding the acceptable as well as the maximum permissible limits specified for drinking and domestic uses. The HPI values were below the critical pollution index level of 100 except at one location. The estimated HQ and HI values for adult and children were greater than the standard limits in nearly half of the water samples. High HQ and HI values suggest that suitable treatment of coal mine water will require before its utilization in domestic and drinking purposes.     

Genetic diversity and heavy metal tolerance in populations of Silene paradoxa L. (Caryophyllaceae): a random amplified polymorphic DNA analysis

Metal-contaminated sites can occur naturally in serpentine outcrops or as consequence of anthropogenic activities, such as mining deposits, aerial fallout from smelters and industrial processes. Serpentine outcrops are characterized by high levels of nickel, cobalt and chromium and present a typical vegetation which includes endemisms and plants which also live in uncontaminated soils. These latter metal-tolerant populations provide the opportunity to investigate the first steps in the differentiation of plant populations under severe selection pressure and to select plants to be used in the phytoremediation of industrially contaminated soils. In this report eight populations of Silene paradoxa L. (Caryophyllaceae) growing in copper mine deposits, in serpentine outcrops or in noncontaminated soil in central Italy, were analysed using random amplified polymorphic DNA (RAPD) markers to investigate the pattern of genetic variation. The genetic diversity observed in populations at copper mine deposits was found to be at least as high as that of the neighbouring serpentine populations. Analysis of molecular variance (AMOVA) of the RAPD markers gave high statistical significance to the groupings of populations according: (i) with their geographical location; and (ii) with the metals present in the soil of origin (copper vs. nickel), indicating that RAPD markers detected a polymorphism related to the soil contamination by copper. Finally, two RAPD bands exclusive to copper-tolerant populations were identified.     

Assessment of heavy metal toxicity related with human health risk in the surface water of an industrialized area by a novel technique

This study innovates an assessment technique to evaluate heavy metal toxic load (HMTL). Assessment of surface water in Durgapur industrial area, West Bengal India illustrates that heavy metals in majority of sampling locations exceed the drinking water quality standards. Therefore, pollution status and health impact were predicted by heavy metal pollution index (HPI) and hazard index (HI). More than 50% of sampling locations were marked as polluted. Moreover, 5% and 90% of sampling locations near the industries have health risk to adult and child on ingestion. The study of specific exposure-time and exposure-duration affirms the suitability of water for fishing and regular activities. However, HPI or HI does not quantify heavy metal concentrations that pose threat to human health. Therefore, the proposed assessment technique, HMTL, determines the concentration of heavy metals responsible for health hazard. HMTL identifies Mn, Pb, and Co as toxic metals and estimates 85%, 63%, and 70% removal of these metals from surface water to limit pollution. Origins of metals were also investigated through statistical techniques, which revealed that Fe has geogenic and anthropogenic source, while other metals originate by anthropogenic activities solely. This study demonstrates that HMTL will help the planning authority to document effective water quality management plan.