High Concentrations Of Heavy Metals Research Articles

Application of Singularity Theory to the Distribution of Heavy Metals in Surface Sediments of the Zhongsha Islands

This research aimed to use nonlinear theory and technology to describe the spatial distribution of heavy metals in the surface sediments of the Zhongsha Islands Sea region. The goal of this study is to explore the spatial distribution characteristics of heavy metals in the surface sediments of the Zhongsha Islands. The singularity theory and method were used to delineate heavy metal geochemical anomalies and the generalized self-similarity analysis method was used to decompose heavy metal geochemical anomalies and background concentrations. The results showed that there were abnormally high concentrations of heavy metals in the deep-sea plain area and in the western central sand trough area. The results of this study can inform priority areas for environmental monitoring. The element anomalies extracted by the singularity analysis method in this paper can be a guide to the next step in the investigation and provide the basis for the regional environmental assessment.

Coastal Groundwater Quality Evaluation and Hydrogeochemical Characterization Using Chemometric Techniques

The physicochemical parameters and heavy metals concentration in the groundwater of the coastal region of Lasbela, Baluchistan were investigated. Cations and anions were determined through ion chromatography. The concentration levels of eight heavy metals (Cr, Cd, Pb, Zn, Fe, Cu, and Mn) in the groundwater were analyzed through the analytical procedures of atomic absorption spectrophotometry. The cations were present in the descending order of magnesium > sodium > calcium > potassium and anions as bicarbonate > sulfate > chloride. Two parameters (bicarbonate and total dissolved solids) were above and other physicochemical indices of groundwater were below the threshold limits of the WHO. Positive correlations of pH and electrical conductivity were observed with cations and anions. The significant positive correlation between sodium and bicarbonate (0.427) indicated the dissolution of carbonate rocks. The concentration of heavy metals (Cu, Cd, Mn, Cr, Pb, Fe, Zn, and Ni) ranged from 0.1 to 0.4, 0.02 to 0.09, 0.04 to 0.9, 0.03 to 0.5, 0.01 to 0.91, 0.05 to 1.30, 0.01 to 0.60, and 0.02 to 0.90 mg/L. The highest concentration of Pb (0.21 mg/L) and Cd (0.16 mg/L) were approximately 20 and 50 times higher than the permissible limits of the WHO. Hierarchical cluster analysis classified the twelve physicochemical parameters into four clusters and the eight heavy metals into seven clusters. Principal component analysis extracted eight latent components for physicochemical properties and heavy metals with eigenvalues greater than 1.0 that had positive loads of fluoride, iron, electrical conductivity, sodium, cadmium, and sulfate. Major pollutants in the groundwater were accounted for by PC 1, and the main factors that affected the water quality were Pb, Cr, and Cu. Fe had a modest impact on the water quality in this region. From the findings, it can be concluded that the coastal groundwater of the region has a higher concentration of heavy metals, which makes it unfit for drinking purposes.

A Dual Media Filter using Zeolite and Mortar for the Efficient Removal of Heavy Metals in Stormwater Runoff

Stormwater runoff from expressways contains high concentrations of various heavy metals. However, heavy metal removal in most current runoff treatment facilities, using infiltration and filtration, is limited and poses substantial risks. Therefore, this study proposes and evaluates a dual media system of mortar and Na-zeolite, which are inexpensive and readily available, using long-term continuous column experiments for the removal of heavy metals. The results showed significant Cu2+ removal with Na-zeolites that was improved by the addition of a thin mortar layer, while a sand layer provided negligible improvements. The removal of Cu was further enhanced by increasing mortar layer thickness. The removal of Cu2+, Zn2+, Fe3+, and Ni2+ in a mixture was enhanced as the mortar layer’s thickness increased, while the contribution of Na-zeolite was significant in 232 h experiments with a fixed empty bed contact time (EBCT) of 1.8 min. Moreover, the media were not saturated with Fe throughout the operation period. These results suggest that the dual media system is cost-effective and efficient in the removal of heavy metals from stormwater runoff via precipitation, filtration, and adsorption with a short EBCT.

Bioremediation of Multiple Heavy Metals Mediated by Antarctic Marine Isolated Dietzia psychralcaliphila JI1D

Extreme environments host numerous microorganisms perfectly adapted to survive in such harsh conditions. In recent years, many bacteria isolated from these inhospitable environments have shown interesting biotechnological applications, including the bioremediation of polluted sites by hydrocarbons and heavy metals. In this work, we present Dietzia psychralcaliphila JI1D, a psychrophilic bacterium, isolated from Deception Island, Antarctica, which is able to resist high concentrations (up to 1000 ppm) of heavy metals and to favor their removal from polluted water systems. In detail, D. psychralcaliphila JI1D can actively promote the sequestration of arsenic, copper, and zinc from the medium up to a maximum of 31.6%, 49.4%, and 38.9%, respectively. Moreover, genome analysis allowed for the identification of heavy metal tolerance genes, thus shedding light on the mechanisms underlying the detoxification ability of the bacterium. Other than the demonstrated ability of D. psychralcaliphila JI1D to degrade polycyclic aromatic hydrocarbons, this study indicates the possibility of using this bacterium in the bioremediation of contaminated matrices, for example, those containing inorganic pollutants.

Genomic Analysis of a Novel Heavy Metal Resistant Isolate from a Black Sea Contaminated Sediment with the Potential to Degrade Alkanes: Plantactinospora alkalitolerans sp. nov.

Microorganisms that grow in poorly studied environments are of special interest when new biotechnological applications are searched. The Melet river offshore sediments at the Black Sea have been described to contain an important number of contaminants from upstream industries which have been accumulating for years. Bacteria of such habitats must be adapted to the presence of those compounds and in some cases, are able to use them as carbon sources. In the analysis of some samples recovered from this environment, an actinobacterial strain was isolated, named as S1510T, and its taxonomic position was determined using a combination of phenotypic and genotypic properties. Strain S1510T presented phenotypic properties typical of members of the family Micromonosporaceae and was assigned to the Plantactinospora genus, based on the phylogenetic analyses of the 16S rRNA gene and whole-genome sequences. Low dDDH (digital DNA-DNA hybridization) values with other members of the genus confirmed that Plantactinospora sp. S1510T represents a novel species, and is proposed with the new name Plantactinospora alkalitolerans. The strain presented characteristics not previously described for other species in the genus, such as its high tolerance to alkaline pHs, the presence of genes related to the production and degradation of alkanes (oleABCD, ssuAD, almA), the degradation of several aromatic compounds, and the tolerance to high heavy metal concentrations. In addition, Plantactinospora sp. S1510T presents several bioclusters to produce nonribosomal peptide-synthetases, terpenes, polyketide synthases, and bacteriocins, that possess low similarities with known compounds.

Migration characteristics and ecological risk assessment of heavy metals in ash from sewage sludge co-combustion in coal-fired power plants

Co-combustion in coal-fired power plants is one of the main methods to dispose of municipal sewage sludge (MSS). The high heavy metals content of MSS increases the ecological risk of ash from the coal and MSS co-combustion. In response to this problem, the three types of fly ash or bottom ash from MSS co-combustion in the three coal-fired power plants were sampled. The properties of fly ash and bottom ash were analyzed in terms of ash composition, particle size distribution, heavy metals content and leaching characteristics. The potential ecological risks were evaluated using the ecological risk index assessment method. The results showed that the co-combustion of MSS had no significant effect on the ash composition order and heavy metals content order. However, the total content of Cu, Mn, Pb and Zn, Hg in the co-combustion ash was higher than that in the coal-fired ash without sludge blending but did not exceed the risk screening value for soil heavy metal contamination of residential land. Heavy metals showed significant enrichment in fly ash and dilution in bottom ash. The leaching concentrations of Cr and Ni were several times the limit value. The potential ecological risk levels of fly ash and bottom ash were moderate risk and high risk respectively. Cr and Hg were the main contributors to potential ecological risks. The contents of Cr, Hg and Ni need to be paid attention to in the subsequent utilization of coal ash mixed with co-combustion of sewage sludge.

Carbonaceous amendment addition as an alternative to decrease phytotoxicity of sediments from the Matanza-Riachuelo Basin (Argentina)

Sustainable management strategies for highly polluted dredged sediments are crucial in ports and waterways, where dredging activities take place on a regular basis. In the case of Argentina, the lack of national legislation enables the unregulated sediment disposal in marginal areas, exposing low-resource populations to these sources of pollution. In order to decrease the sediment phytotoxicity for the potential revegetation of dredged sediments from the Matanza-Riachuelo River, with high concentrations of heavy metals, the effect of two types of carbonaceous amendments (biochar, BC, and commercial activated carbon, AC) in different proportions (10% and 20%) was studied. With the defined treatments, germination and root elongation tests, and seedling-level tests were carried out to compare the phytotoxicity of the amended sediments with that of the pure sediment. Lettuce ( Lactuca sativa ) was used as an indicator species. Both amendments in the highest dose (AC20% and BC20%) improved germination index. AC20% presented the highest heavy metal accumulation in biomass for all the metals under analysis, but plants did not exhibit negative morphological alteration or phytotoxic symptoms. By contrast, BC treatments did not improve lettuce’s morphological variables and heavy metal accumulation significantly. Together with adequate agronomic practices, the appropriate selection and dosage of carbonaceous amendments could be a useful strategy to modify the physicochemical conditions of the sediment conveniently, and promote either heavy metal mobilization or stabilization. • The effect of carbonaceous amendments was studied in a heavy metal polluted sediment. • The type of amendment (biochar, activated carbon) and dose (10%, 20%) were compared. • Treatments BC20% and AC20% improved lettuce’s germination index. • AC20% also improved lettuce’s growth parameters significantly. • AC increased Cu, Cr, Zn and Pb uptake by lettuce with no phytotoxic symptoms.

Agglomeration-influenced transformation of heavy metals in gas-solid phases during simulated sewage sludge co-incineration: Effects of phosphorus and operating temperature

Phosphorus and operating temperature not only affect the agglomeration behavior but also the transformation and migration of heavy metals. Accordingly, this study examined the effect of temperature and phosphorus in a fluidized bed combustion process to understand the emission and distribution of heavy metals by both experimental and thermodynamic calculations. The experimental results indicated that the sodium-phosphate reactions occur before the sodium-silicate reaction in the solid phase when the ratio of P/Na was 1/2. A low-melting-point sodium phosphate component, such as NaPO3, leads to easier particle agglomeration than Na2O-SiO2. In terms of the emissions of heavy metals, Pb and Cd show a similar trend: both the amount of emission smaller than that without adding phosphorus and the amount of emission share an upward trend with the operating time increased during MSS fluidized bed combustion. However, with the presence of phosphorus, the emission of Cr shows slightly decreased, and then sharply dropped, after that, increasing with operating time increased. Generally speaking, the maximum amount of Pb and Cd emitted was at 900 °C, followed by 800 °C and 700 °C. The higher temperature would promote the volatilization of Pb and Cd to emit. On the other hand, Cr emitted at the beginning tended to increase but later decreases when the temperatures were 700 and 900 °C, which may be due to the emission of Cr being influenced by the different affinities of both Al and Cr, reacting with Na in a fluidized bed incinerator. As for the distribution of heavy metals in the solid phase, a higher concentration of heavy metals was found in both the coarsest and finest particles during the process of agglomeration/defluidization.

Widespread bacterial responses and their mechanism of bacterial metallogenic detoxification under high concentrations of heavy metals

Microbial mineralization is increasingly used in bioremediation of heavy metal pollution, but better mechanistic understanding of the processes involved and how they are regulated are required to improve the practical application of microorganisms in bioremediation. We used a combination of morphological (TEM) and analytical (XRD, XPS, FTIR) methods, together with novel proteomic analyses, to investigate the detoxification mechanisms, used by a range of bacteria, including the strains Bacillus velezensis LB002, Escherichia coli DH5α, B. subtilis 168, Pseudomonas putida KT2440, and B. licheniformis MT-1, exposed to elevated concentrations of Cd2+ and combinations of Cd2+, Pb2+, Cu2+, and Zn2+, in the presence and absence of added CaCl2. Common features of detoxification included biomineralization, including the production of biological vaterite, up-regulation of proteins involved in flagellar movement and chemotaxis, biofilm synthesis, transmembrane transport of small molecules and organic matter decomposition. The putative roles of differentially expressed proteins in detoxification are discussed in relation to chemical and morphological data and together provide important tools to improve screening, selection, and practical application of bacterial isolates in bioremediation of polluted environments.

Variation in soil chemical properties in relation to vegetation characteristics in a serpentine area of Hokkaido, Japan

Serpentine soils typically have chemical characteristics that can create adverse conditions for plant growth (e.g., low plant nutrients, low Ca/Mg ratio, and high heavy metal concentrations). Many studies have reported the unique characteristics of soils and plant communities (including endemic plants) in serpentine areas, especially on outcrop landscapes. However, little is known about variation in soil conditions within the geographical range of serpentine areas, such as from outcrops to adjacent grasslands and forests. The objective of this study was to assess the variation in soil chemistry among vegetation types in a serpentine soil area. We measured the chemical properties of soils for four vegetation types: outcrop, grassland, forest-edge, and mid-forest, in a serpentine area of Hokkaido, Japan. The results showed wide variation in the chemical properties of soil among vegetation types. In particular, outcrop and grassland sites showed extremely low Ca/Mg ratios and had higher Ni concentrations than those for the two forest sites. In addition, these differences in soil chemistry were strongly related to soil carbon content. These results suggest that forest litter alters the soil chemistry in serpentine areas, via soil development associated with organic matter accumulation, to conditions that are more conducive to a broader range of plants.

Heavy Metal Pollution and Risk Assessment of Surface Dust in the Arid NW China.

High concentrations of heavy metals (HMs) in urban surface dust (USD) can be extremely hazardous to urban ecology and human health. Oasis cities are located at the edge of deserts and are more exposed to salt/sandstorms, and they face a significantly higher accumulation of USD than wet or semi-humid areas. However, systematic studies on the pollution and risk assessment of HMs in USD in oasis cities have rarely been conducted. This study systematically analyzed the enrichment status, spatial distribution, pollution levels, health risks, and sources of HMs in USD in a typical oasis city (Changji city). The results showed that the average concentrations of Pb, Ni, As, Cd, Hg, and Cu in the USD of Changji city were 46.83, 26.35, 9.92, 0.21, 0.047, and 59.33 mg/kg, respectively, and the results of the pollution index evaluation showed moderate Pb, Hg, and Cu pollution, mild Cd pollution, and no Ni or As pollution. The spatial distribution of HM concentrations in the USD was substantially heterogeneous. High values of Pb, Hg, and Cu concentrations were mainly observed in areas with relatively intensive transportation and commercial activities, and high values of Cd and Ni were observed in industrial areas. The health risk assessment showed that HMs do not pose non-carcinogenic risks to humans at their current level, but they pose a carcinogenic risk to children, with As contributing the largest carcinogenic and non-carcinogenic risks. The source identification of HMs showed that the main pollution of HMs were traffic sources for Pb and Cu, industrial sources for Ni and Cd, natural sources for As, and coal-fired sources for Hg. According to the results of the quantitative analysis with the positive matrix factorization, the contribution of pollution sources followed this order: industrial sources (31.08%) > traffic sources (26.80%) > coal-fired sources (23.31%) > natural sources (18.81%).

The ignored risk: heavy metal pollution of medicine and food homologous substances.

A survey was conducted to investigate the effects of cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and copper (Cu) in medicine and food homologous substances (MFHs) on human health. Nine common and typical MFHs (Dendrobium, Bulbus lilii, Poria, Semen nelumbinis, Radix puerariae, Gardenia jasminoides, Hordeum vulgare L, Semen coicis, and Ganoderma Karst) in the form of medicinal slices ready for decoction were purchased from pharmacies. Five among the MFHs (Dendrobium, Bulbus lilii, Poria, Semen nelumbinis, and Radix puerariae) were further obtained from a local field as raw materials for comparison. The results showed that raw materials of MFHs collected from the field had higher contents of heavy metal and greater health risks than medicinal slices purchased from pharmacy. Generally, the heavy metal residues in MFHs of different medicinal parts were different, and MFHs from roots or stems had significantly higher contents of heavy metals than those from fruits or seeds. Most importantly, the contents of Cd in Bulbus lilii and As in wild Poria from field were higher than the contents described in the Pharmacopoeia of the People's Republic of China (ChP). Non-carcinogenic and carcinogenic risk assessments revealed that Poria from field had larger non-carcinogenic and carcinogenic risks to human health; Bulbus lilii showed no non-carcinogenic risk but exhibited carcinogenic risks, whereas Cr showed carcinogenic risks in all samples. Given that MFHs are incorporated in regular foods, care should be taken to minimize health hazards caused by heavy metals to human. This study creates awareness on the safety issues associated with MFHs, and provides basic information for establishing the maximum allowable contents of medicinal and food substances in normal diets.

Enhanced biodegradation of oil-contaminated soil oil in shale gas exploitation by biochar immobilization.

The enhanced biodegradation of oil-contaminated soil by fixing microorganisms with corn cob biochar was investigated. It was found that the components of oil in the test soil were mainly straight-chain alkanes and branched alkanes. When using corn cob biochar as a carrier to immobilize microorganisms, the best particle size of corn cob biochar as an immobilization carrier was 0.08mm, and the best immobilization time was 18h. SEM analysis confirmed that the microorganisms were immobilized on the corn cob biochar. Immobilized microorganisms exhibited high biodegradability under stress to high concentrations of petroleum pollutants, heavy metals, and organic pollutants. Infrared spectroscopy analysis showed that oxygen-containing groups such as hydroxyl, carboxyl, and methoxy on the surface of biochar were involved in the complexation of heavy metals. The mechanism of immobilization promoted microbial degradation of oil contamination was explained by gas chromatography mass. First, alkanes and aromatics were adsorbed by corn cob biochar and passed to immobilized microorganisms to promote their degradation. Their bioavailability increased, especially for aromatics. Second, biochar provided a more suitable environment for microorganisms to degrade. Third, the conversion of ketones to acids was accelerated during the biodegradation of alkanes, and the biodegradation of alkanes was accelerated by immobilization. The biodegradable efficiency of oil by immobilized microorganisms in soil was 70.10% within 60days, 28.80% higher than that of free microorganisms. The degradation of immobilized microorganisms was highly correlated with the activities of catalase, urease, and polyphenol oxidase.

Mechanism of Lead-zinc Enrichment and Resistance of Spent Mushroom Compost to Lead-Zinc Slag in Koelreuteria paniculata

Phytoremediation is an ecological technique for tailing area restoration; adding substrate modifiers can reduce the stress of heavy metals on plants and enhance the restoration efficiency. The woody plant Koelreuteria paniculata was used as a test plant and potted in 100% tailings (S), 90% tailings+5% mushroom residue (SMC)+5% CaCO3 (MS), and natural red soil (RS). The effects of physiological responses and tolerance enrichment effects on Pb and Zn tolerance in K. paniculata under different treatments were investigated to compare the growth morphology, microscopic morphological changes, and microbial diversity changes in each substrate of K. paniculata seedlings. The results showed that compared with the control group S, the MS treatment group could significantly improve the structure and fertility of the tailing substrates; significantly enhance the relevant physiological indicators such as biomass, plant height, and chlorophyll content of K. paniculate; and increase the accumulated heavy metal content in K. paniculata. In the treatment group, the overall physiological indexes of MS compared to RS biomass and plant height were promoted, and the total root length increased up to 69.3%, whereas the average root diameter of RS in the treatment group decreased 118.7% compared to that in the control group S. The MS treatment group showed a 266.67% increase in Pb and Zn residue state, a significant decrease in the weak acid extractable state and oxide-bound state compared to that in the control group S. The heavy metals were less active for plant migration. Furthermore, most of the heavy metals were trapped in the roots of K. paniculata, and the changes in its root conformation indicated its strong adaptability in the face of high Pb stress. Transmission electron microscopy (TEM) analysis showed that the higher concentration of heavy metals in the S control damaged the cell wall structure and caused toxic effects on plant cells. The addition of the modifier effectively alleviated the effects of heavy metal stress on various tissues of K. paniculata, affected the structure of microbial communities, significantly increased microbial richness and diversity, and enhanced the adaptability of K. paniculata to heavy metals and phytoremediation ability.

Electrochemical Responses and Microbial Community Shift of Electroactive Biofilm to Acidity Stress in Microbial Fuel Cells

Microbial community changes in response to acid stress in microbial fuel cells (MFCs) were studied. Acid mine drainage (AMD) wastewater is usually difficult to treat because of the high concentration of sulfate and heavy metals. MFCs, which have multiple functions based on the principle of synergistically treating organic and heavy metal wastewater while generating electrical energy, represent a promising direction for the development of new heavy metal wastewater treatment technologies. Maintaining a neutral or slightly alkaline wastewater pH in MFCs facilitates the growth of electricity-producing microorganisms in the anode chamber. Studies on the response of anode electroactive biofilms to acidic pH stress and its correlation with changes in AMD treatment capacity have not been reported. Results showed that the anolyte pH of 4.0 and 5.0 affected the electron output capacity of the electrogenic microbial community in the MFCs. In contrast, MFCs working at an anolyte pH of 6.0 exhibited a high efficiency of chemical energy conversion to electrical energy. The microbial abundance and microbial diversity of the electroactive biofilm were significantly affected by the H+ concentration in the medium when the ambient acidity was continuously reduced. The classic exoelectrogen Geobacter decreased gradually with the increase of H+ concentration in the medium. In addition, Cu2+ was recovered from the simulated AMD in the MFCs cathodic chambers at low anode pH, but the removal rate of Cu2+ decreased as the pH of the anode environment decreased. At 48 h, 86.2% of Cu2+ was removed from the MFCs cathode solution at pH 5.0, while the removal rate of Cu2+ from the MFCs cathode solution at pH 4.0 was 84.2%. Trace amounts of Cu2O and Cu3(OH)2[CO3]2 were present on the cathode, which reduced the amount of Cu2+ that precipitated on the cathode carbon cloth. Conversely, the concentration of Cu2+ in the catholyte of MFCs with electroactive biofilm at pH 6.0 decreased rapidly, and by 36 h, no detectable Cu2+ was present in the cathodic solution. This study will provide researchers with valuable information regarding the optimal pH for resource recovery with MFCs.

Exploring the variation of bacterial community and nitrogen transformation functional genes under the pressure of heavy metals in different coastal mariculture patterns

Equilibrium in microbial dynamics and nitrogen transformation in the sediment is critical for maintaining healthy mariculture environment. However, our understanding about the impact of heavy metals on the bacterial community and nitrogen transformation functional genes in different mariculture patterns is still limited. Here, we analyzed 30 sediment samples in the vertical distribution from three different mariculture patterns mainly include open mariculture zone (K), closed mariculture pond (F) and pristine marine area (Q). Illumina MiSeq Sequencing was applied to investigate the bacterial community and structure in the sediment. Quantitative polymerase chain reaction (qPCR) was used to determine the effect of heavy metals on nitrogen transformation functional genes. Results showed that bacterial community and structure varied greatly in different mariculture patterns. Chloroflexi, Proteobacteria and Desulfobacterota were predominant phyla in the coastal mariculture area. High concentrations of heavy metals mainly enriched in the up layer (5–40 cm) of the sediment in the mariculture zone. The abundance of functional genes in the closed mariculture pond was much higher than the open mariculture zone and pristine marine area. And the high abundance of nitrification and denitrification functional genes mainly accumulated at the depth from 5 cm to 40 cm. Heavy metals content such as Fe, Cr, Mn, Ni, As, Cd, Pb and nutrient content NH4+-N, NO3−-N and NO2−-N were highly associated with bacterial community and nitrogen transformation functional genes. This study comprehensively elaborated the effect of heavy metals on the bacterial community and nitrogen transformation functional genes in different coastal mariculture patterns, indicating the possible role of closed mariculture pond in reducing nitrogen transformation efficiency, which will provide useful information for preventing pollution risk in the mariculture area.

Algae, biochar and bacteria for acid mine drainage (AMD) remediation: A review

Acid mine drainage (AMD) is a global issue and causes harmful environmental impacts. AMD has high acidity and contains a high concentration of heavy metals and metalloids, making it toxic to plants, animals, and humans. Traditional treatments for AMD have been widely used for a long time. Nevertheless, some limitations, such as low efficacy and secondary contamination, have led them to be replaced by other methods such as bio-based AMD treatments. This study reviewed three bio-based treatment methods using algae, biochar, and bacteria that can be used separately and potentially in combination for effective and sustainable AMD treatment to identify the removal mechanisms and essential parameters affecting AMD treatment. All bio-based methods, when applied as a single process and in combination (e.g. algae-biochar and algae-bacteria), were identified as effective treatments for AMD. Also, all these bio-based methods were found to be affected by some parameters (e.g. pH, temperature, biomass concentration and initial metal concentration) when removing heavy metals from AMD. However, we did not identify any research focusing on the combination of algae-biochar-bacteria as a consortium for AMD treatment. Therefore, due to the excellent performance in AMD treatment of algae, biochar and bacteria and the potential synergism among them, this review provides new insight and discusses the feasibility of a combination of algae-biochar-bacteria for AMD treatment.

A Cross-section Metagenomics and 16S Ribosomal DNA Based Evaluation of the Bacterial and Archaeal Communities Resident in the Forumad Chromite Mine, Northeastern of Iran.

The Forumad chromite area from Sabzevar ophiolite belt, Northeastern Iran, is an environment with high concentration of heavy metals, particularly chromite and magnesite minerals, containing chromium and magnesium. In this study for the first time, we analyzed and report the diversity of microbial (bacterial and archaeal) community inhabiting in Forumad chromite mine environment using metagenomics approach. Samples were obtained from different areas of the mine, and total DNA was extracted from water and soil samples. 16S rDNA was amplified using universal primers and the PCR products were cloned in pTz57R/T plasmid. Then, 43% of the positive clones were randomly sequenced. BLAST program in NCBI and EzTaxon databases were used to identify similar 16S rDNA sequences. Phylogenetic analysis was performed using the MEGA5 software and multiple alignments of sequences. In the phylogenetic analyses, proteobacteria, which contains many heavy metals tolerant bacteria especially chromium, were the dominant population in bacterial libraries with Rheinheimera and Cedecaeas the most abundant genuses. Other phyla were Bacteroidetes, Firmicutes, Verrucomicrobia, Chloroflexi, Actinobacteria, Acidobacteria, Cyanobacteria, Gemmatimonadetes, and Planctomycetes. In the archaeal clone library, all the sequences were related to the phylum Thaumarchaeota. Further, 68.6% of the sequences had less than 98.7℅ similarity with the recorded strains which could represent new taxons. The results showed that there was a high microbial diversity in the Forumad chromite area. These results can be used for detoxification and bioremediation of regions contaminated with heavy metals, although more studies are needed.

Characterisation of aluminium industrial wastewater and investigation of recovery alternatives

Aluminium industry is one of the largest sectors and wastewater generated from this industry could cause crucial environmental problems due to its high heavy metal concentration and conductivity. Therefore, this study aims to determine the characterisation of the wastewater discharged from the two aluminium facilities by considering water recovery potential. While Facility-A produces stainless steel kitchenware, such as pots and pans, In Facility-B, anodised coating takes place from secondary aluminium and wastewater is generated from the units where anodised coating baths and control processes are carried out. For the analyses, the wastewater composite samples from different sections, such as washing, sand-blasting and dyeing in Facility-A were taken in 2 and 24 hours. In Facility-B, three 2-hour composite influent water samples and an effluent sample from chemical wastewater treatment were taken to determine conductivity, pH, chemical oxygen demand (COD), total suspended solids (TSS), etc. As a result of the analyses made, a high value of TSS was detected at all sampling points in Facility-A. It was also seen that the conductivity after demineralisation process in Facility-A was below 30. In Facility-B, it was determined that while the pH obtained from two influent samples was below the discharge limits and showed acidic characteristics, one sample was very basic with a pH value of 12.19 and exceeds the upper limit of discharge. All influent samples in Facility-B show high TSS content in comparison with discharge limits specified in the regulation.

Heavy metals in paired samples of hair and nails in China: occurrence, sources and health risk assessment.

The occurrence of heavy metals including chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) was investigated in paired samples of hair and nails collected from 121 volunteers in 16 cities, China. Results showed that the mean concentrations of Zn, Cu, As, Pb, Cr, Ni and Cd were 205, 18.0, 7.79, 6.18, 3.54, 2.02, 0.533μgg-1 in hair and 103, 8.09, 0.760, 7.27, 6.07, 8.81, 0.485μgg-1 in nails, respectively. The concentrations of Zn, Ni, Cr, Cd and Pb were positively correlated in paired samples of hair and nails, whereas a negative correlation was found for Cu and As between hair and nails. Higher concentrations of heavy metals were found in northern China than southern China. The multivariate analysis of variance revealed that dwelling environment was the dominant factor influencing the levels of Cd in hair (p < 0.05), while age was the dominant factor influencing the levels of Cr in nails (p < 0.05). Moreover, industrial pollution and smoking were also the important factors leading to the accumulation of heavy metals in human body. Principal component analysis (PCA) showed that industrial pollution and decoration material immersion were the main factors for the high concentrations of Cr and Ni in hair, accounting for 62.9% of the total variation; As in hair was dominantly related to groundwater pollution. The concentrations of heavy metals were within the recommended ranges in nails from this study. However, the mean levels of Cr, Ni and As in hair exceeded their recommended reference values, indicating potential health risks from heavy metals for residents in China.