Order Of Pb Research Articles

Citrate coated magnetite: A complete magneto dielectric, electrochemical and DFT study for detection and removal of heavy metal ions

The super paramagnetic iron oxide nanoparticles (SPIONs) such as magnetite (Fe3O4) appear as an emerging class of materials in the field of environmental remediation owing to its biocompatibility, high surface area, super paramagnetic properties and ease of reuse and recovery. However, susceptibility of bare Fe3O4 to oxidation and agglomeration limits its use as an adsorbent material in aqueous medium, which demands the surface capping of these Fe3O4 nanoparticles for effective adsorption performance. We have successfully capped Fe3O4 with sodium citrate with a purpose to develop a felicitous magnetic sorbent material containing abundant metal trap centers at its surface. The successful surface modification of Fe3O4 with citrate is noticeable from FT-IR, TGA, XRD, Zeta potential (DLS), SEM, EDX,TEM, DR-UV, and contact angle measurements. For the first time, we report electrical impedance spectroscopic studies on this capped magnetic nanoparticle to understand the capacitive behavior of super paramagnetic Fe3O4 and citrate@Fe3O4 nanoparticles. The cyclic voltammograms manifested the excellent electrochemical response of citrate@Fe3O4 modified glassy carbon electrode to mM concentrations of Pb2+, Cd2+ and Zn2+ ions with response in order Pb2+> Cd2+> Zn2+. Differential Pulse Voltammetry confirms the descent sensitivity towards Pb2+ ions at different concentration with a 0.3 µM detection limit. The adsorption of Pb2+ ions followed Langmuir isotherm model with maximum monolayer adsorption capacity of 58.93 mg g−1. To further validate the experimental adsorption results and the mode of interaction between Pb2+and citrate@Fe3O4, quantum calculations using density functional theory were performed which indicate a good coherence between experimental and theoretical data. The presence of abundant carboxyl and hydroxyl metal trap centers at the surface of citrate@Fe3O4 is responsible for its promising adsorption capacity for Pb2+ ions removal. Both experimental as well as theoretical results suggest that surface functionalization has a positive impact for detection of heavy metal ions and should be given prime importance while designing absorbent materials. The citrate@Fe3O4 nanoparticles exhibit outstanding stability and regeneration over various cycles of sorption.

Health risk assessment and bioaccumulation of metals in brown and red seaweeds collected from a tropical marine biosphere reserve

In the present study, we have assessed the degree of contamination of heavy metals (Cd, Cu, Pb, and Zn) in ten species of red and brown seaweeds, the seasonal variations in the concentration of metals, and the health risk due to the seaweeds. Overall metal concentrations for red and brown seaweeds followed the order Pb > Zn > Cu > Cd and Pb > Cu > Zn > Cd, respectively. Cd and Pb levels were found to be elevated in both the red and brown seaweeds. Multivariate statistical analysis revealed that the sources of Cd and Pb are mainly anthropogenic. Despite the high concentrations of the non-essential metals (Cd and Pb) in the seaweeds, the health risk assessment revealed that they have a lower hazard index. Hence, consumption of edible red and brown seaweeds from the Tuticorin coast may not pose health hazards in humans for the time being.

Evaluation of the interactions of arsenic (As), boron (B), and lead (Pb) from geothermal production wells with agricultural soils

Geothermal energy is a low-pollution energy source. However, air, soil, and water near geothermal plants may be affected by their operation. One of the largest geothermal energy sources in the world, Cerro Prieto, has a capacity of 720 MW and is located in northwest Mexico near an agricultural area. The abstracted geothermal fluids, which are enriched with arsenic (As), boron (B), lead (Pb), cadmium (Cd), and other heavy metals, are either reinjected into the aquifer or sent to an evaporation pond located in the geothermal plant. Because spills have occurred in other geothermal zones, it is important to evaluate the effect of those contaminants on the soils of the surrounding area and their possible infiltration into shallow groundwater. To that aim, soils (one chromic Vertisol and two calcic Regosols) from three sites near the Cerro Prieto Geothermal Plant were sampled to evaluate their behavior regarding As, Pb, and B retention. Batch experiments were carried out using the soils as the sorbent and geothermal water from three geothermal production wells as the sorbate. Raw water concentrations in each well were as follows: As: 0.2442 mg/L, 0.2774 mg/L, and mg/L; B: 18.409 mg/L, 13.5075 mg/L, and 16.646 mg/L; and Pb: 0.22 mg/L, 0.13 mg/L, and 0.26 mg/L. The physicochemical characteristics of the soils were determined and compared to the experimental results. A good adjustment of the chromic Vertisol sample to Freundlich isotherms was observed for As (r2 > 0.9), followed by Pb (r2 = 0.61), and B (r2 > 0.5). As retention also showed a good adjustment to the Langmuir model (r2 > 0.9). The retention followed the order Pb >As ≫B in one of the two calcic Regosols, while the other only retained Pb ≫ As. Cationic exchange capacity; clay minerals; carbonate; organic matter; and iron, aluminum, and manganese amorphous and crystalline oxides influenced the soils’ retention capacities. Irrigation with geothermal water could not imply a toxicity risk to plants grown in the chromic Vertisol soil due to its high Pb and As sorption capacity. Pb concentration could not be a toxicity issue in the calcic Regosols for the same reason, but As and B could be. B would be a hazard to vegetables and water due to its low or lack of retention in the three soils and also for its possible infiltration into shallow groundwater used for irrigation in the area. This study highlights the importance of maintaining adequate operation and control of the disposal of geothermal fluids in geothermal plants.

Heavy metal distribution in particle size fractions of floodplain soils from Dongchuan, Yunnan Province, Southwest China.

The heavy metal pollution level in soils is heavily affected by the soil particle size distribution. However, the heavy metal loss during particle size extraction and the effect of calcite on the heavy metals removal in terms of the particle size are unclear. In this study, the distribution of heavy metals (Cu, Cd, Cr, Co, Ni, Zn, Pb, U, and V) was determined in five particle fractions (> 2, 2-0.25, 0.25-0.02, 0.02-0.002, and < 0.002 mm) of two soil and one sediment samples collected from the floodplain of Dongchuan, Yunnan Province, Southwest China. The sampled floodplain soils were mainly composed of gravel and sand fractions (> 97%). The concentrations of all nine heavy metals in the sampled soils and sediment increase significantly with decreasing particle sizes. The maximal loss rate of Cd and Cu reaches 54% and 8.6%, respectively, which should be considered in the process of particle size fraction extraction in soils. The removal amount and removal rate of heavy metals in solution by pure calcite ranks in the order of Pb2+ > Cu2+ > Cr6+, while the removal rate of Pb (93.13%) is much higher than that of Cu (24.56%) and Cr (10.71%), which increase with the calcite particle size decreasing. The stabilization of carbonate minerals in soils is crucial for heavy metal pollution control in floodplain soils with high carbonate concentrations in Dongchuan, China.

Recycling of Steel Industry Waste Acid in the Preparation of Fe3O4 Nanocomposite for Heavy Metals Remediation from Wastewater

This study was steered to convert waste acid ensued from the pickling process in steel industries to an esteemed nanocomposite for the elimination of heavy metals (HMs) from wastewater. Magnetic nanoparticles (Fe3O4) preparation from waste was performed by the co-precipitation method. These magnetic nanoparticles are modified by carboxymethyl-a-cyclodextrin polymer (CM-a-CD) through copolymerization reactions. The data obtained from FTIR, XRD, and TEM point up that CM-a-CD is entrenched onto Fe3O4 nanoparticles. The generated CM-a-CD / Fe3O4 was employed for HMs deportation from contaminated water and the adsorption results revealed that CM-a-CD/ Fe3O4 sorption efficiency was in the order of Pb(II) ] Cd(II) ] Cr(VI). The highest adsorption capacity was 64.2 (mg/g) for Pb(II). The kinetic study revealed that the HMs sorption by CM-a-CD/ Fe3O4 follows the pseudo-second-order model. The equilibrium modeling study proved that the Langmuir isotherm model was more fitting. The coexisting ions do not significantly alter the percentage removal of the measured metal ions. The efficiency of the synthesized polymer is particularly high in the tested field samples. Thus, CM-a-CD/ Fe3O4 has an extremely high adsorption capability in the field application as well as excellent reusability results, which will reduce the cost for the CM-a-CD / Fe3O4 as an adsorbent for wastewater treatment.

Nature of High- and Low-Affinity Metal Surface Sites on Birnessite Nanosheets

Birnessite nanosheets (δ-MnO2) are key reactive nanoparticles that regulate metal cycling in terrestrial and marine settings, yet there is no molecular explanation for the sorption selectivity of metals which controls their enrichment. This fundamental question was addressed by optimizing the structure of Ni, Cu, Zn, and Pb surface complexes on δ-MnO2 and by calculating the Gibbs free-energy change (ΔG) of the sorption reactions with density functional theory. The sorption selectivity follows the order Pb > Cu > Ni > Zn in good agreement with experimental data. Cu, Ni, and Zn bind preferentially to layer edges at low surface coverage forming double-edge-sharing (DES) complexes, whereas Pb binds extensively with high selectivity over the three transition metals to both layer edges (DES bonding) and to basal planes forming triple-corner-sharing (TCS) complexes. Pb has a similar affinity for the DES and TCS sites at pH 5 and a higher affinity for the TCS sites at circumneutral pH. The Pb DES and TCS complexes are both dehydrated at the δ-MnO2–water interface and feature a trigonal pyramidal geometry with three surface O atoms. The high stability of the two new Pb complexes arises from the hybridization between the Pb 6s/6p and O 2p states, forming a strong covalent Pb–O/OH bond at the δ-MnO2 surface. The quantum chemical results provide a mechanistic and energetics insight into the metal uptake on δ-MnO2 that extends what extended X-ray absorption fine structure (EXAFS) spectroscopy alone can provide.

Mercury, cadmium, and lead in cigarettes from international markets: concentrations, distributions and absorption ability of filters.

Mercury (Hg), cadmium (Cd), and lead (Pb) concentrations in marketed cigarettes from South Korea, Vietnam, Japan, Indonesia, Taiwan, Thailand, the United Kingdom (UK), Belgium, Italy, Finland, and France were investigated. The cigarettes from Vietnam and Thailand had the highest trend of Hg. Meanwhile, Cd was found higher in cigarettes from Thailand, the UK, and Belgium. Pb concentrations in cigarettes from Belgium, the UK, and Korea were higher than others. The average of these heavy metals concentrated in cigarettes was in the order of Pb > Cd > Hg. Furthermore, the contents of these heavy metals in cigarette leaves were much higher than in filter and rolling paper. There was a significant positive correlation between Hg and Cd, but no correlation between Cd and Pb and between Hg and Pb. Significant positive correlations of nicotine with Hg and Cd but not Pb in the cigarette were observed. Activated carbon filters (Ce-C) absorb Cd and Pb from cigarette leaves and rolling paper indicated a higher trapping trend than cellulose acetate filter without activated carbon (Ce). The trapping ratios of Ce-C (Cd: 5.53%, Pb:5.41%) were higher than Ce (Cd:3.09%, Pb:5.49%). On the other hand, Hg had lower absorption by both types of filters (Ce:0.15%, Ce-C:0.02%). This revealed that Hg, Cd and Pb absorption ability by both filters was relatively lower to the total concentration of these metals in tobacco leaves and rolling paper. The concern was that the higher concentrations of metals such as Hg, Cd and Pb in cigarettes might exist in mainstream smoke.

Health Risk Assessment of Heavy Metals in Groundwater of Industrial Township Virudhunagar, Tamil Nadu, India.

The present investigation deals with the health risk assessment due to the heavy metals (Cd, Cr, Cu, Co, Mn, Pb, Ni, and Zn) in groundwater in the industrial township of Virudhunagar district. Twenty groundwater samples were collected, and the measured concentration of the heavy metals follows the order Pb > Ni > Zn > Co > Cr > Cd > Cu > Mn. The metal pollution indices (heavy metal evaluation index, Heavy metal pollution index, degree of contamination) were calculated using the measured heavy metal concentrations. The samples collected nearer to the industrial zone have elevated concentrations of Pb, Cd, and Ni. The carcinogenic and noncarcinogenic risks were calculated based on the measured heavy metals concentration and average daily intake of water. The calculated carcinogenic risk values (5.66 × 10-3-1.56 × 10-2) (Pb, Cd, and Ni) exceed the acceptable limit of 10-6-10-4. The noncarcinogenic risk exceeds the acceptable limit of one for the heavy metals Pb and Cr. The higher carcinogenic and noncarcinogenic risk values reveal that the study area has health risks due to Pb, Cd, Ni, and Cr metals. Furthermore, factor analysis and cluster analysis showed that the industrial impact and wastage dumpsites are the prime sources for heavy metal contamination in groundwater of the study area.

Ecological and Human Health Risk Assessment of Sediments near to Industrialized Areas along Langat River, Selangor, Malaysia

ABSTRACT Rapid industrialization at Kuala Langat, Selangor have raised environmental and health concerns among the public. Surface sediments from a total of 10 stations, covering the upstream and downstream sites near to plastic recycling factories along Langat River were collected and analyzed for its physicochemical properties, bioavailable heavy metals concentration and pollution degree. Ecological risk assessment of heavy metals was carried out using several pollution indices such as geoaccumulation index (), contamination factor (CF), contamination degree (CD), enrichment factor (EF), pollution load index (PLI) and potential ecological risk index (PERI). For human health risk assessment, non-carcinogenic risk of heavy metals (Cd, Cr, Cu, Pb and Zn) was assessed using hazard quotient (HQ) and hazard index (HI) whereas carcinogenic risk of heavy metals (Cd, Cr and Pb) was assessed using carcinogenic risk index (RI) and total risk (TR). The heavy metal accumulation in sediments in terms of concentration was in the order of Pb > Zn > Cu > Cr > Cd and the mean concentration of the heavy metals were lower than the background value except Pb. The PLI result indicated that the sediment at Langat River was unpolluted but posed low ecological risk by Cr, Cu and Zn, low to moderate ecological risk by Cd, and low to considerable ecological risk by Pb as shown by PERI result. However, non-dietary ingestion of sediment from Langat River showed possible risk of non-carcinogenic effects at certain sites whereas tolerable carcinogenic risk at almost all sites. Organic matter, silt, clay, pH and base saturation showed significant relationship with the heavy metals concentration, indicating the transformation and accumulation factor of heavy metals in river sediment. This study is important to increase the awareness of sediment pollution at Langat River and provide information to the stakeholders in Kuala Langat for future planning and policies to protect the local ecosystem and residents.

Quality of Peri-Urban Soil Developed from Ore-Bearing Carbonates: Heavy Metal Levels and Source Apportionment Assessed Using Pollution Indices

Pollution indices are used to assess the influence of the bedrock as a natural source of heavy-metal (HM), and anthropogenic pollution from ore mining in soils developed from ore-bearing carbonates. The research was conducted in two areas differing in geological setting and type of land use in the Upper Silesia Industrial Region, Southern Poland. Physical properties such as pH, total sulfur, total carbon and total organic carbon values, as well as total Zn, Pb, and Cd contents (ICP-OES) for 39 topsoil samples were measured. Contamination factor (Cf), degree of contamination (Cdeg), pollution load index (PLI) and geoaccumulation index (Igeo), were used to determine the deterioration of topsoil due to HM pollution. The HM content exceeded geochemical background levels by 2.5–18.1 times. Very high to moderate topsoil contamination was determined. In a shallow historical mining zone, the relative influence of particular HM was found to be in the order of Pb &gt; Cd &gt; Zn and, in a deep mining zone, Zn &gt; Cd &gt; Pb. In the topsoil developed over shallow ore bodies, the HM content was mainly (60%) due to naturally occurring HM. In the area of deeply buried ore bodies, 90% of the HM load was related to anthropogenic sources. Zn, Pb and Cd vertical distributions and the patterns of topsoil pollution differ in terms of types of mined ores, mining methods and times elapsed since mining ceased. Pollution indices are an efficient tool for distinguishing soil anthropogenic pollution and geogenic contamination.

Concentrations and health risk assessment of industrial heavy metals pollution in groundwater in Ogun state, Nigeria

Wastes from industrial activities had great impact on water quality thereby limiting water usability for domestic purposes. Effluents discharge from industries, usually consist of undesirable concentrations of dissolved chemicals that percolate into the groundwater, thus constitute health risk to the populace. The present study assessed the distribution of heavy metals in groundwater and their health implications. Water samples were collected from hand-dug wells and boreholes in the Ota and Sagamu Industrial areas of Ogun state, Nigeria during the rainy and dry seasons. A total of 96 samples (48 samples per season) were collected and subjected to metals analysis (lead (Pb), cadmium (Cd), chromium (Cr), Nickel (Ni), Iron (Fe), Zinc (Zn), Copper (Cu), and Manganese (Mn) using standard methods. Descriptive and inferential statistics were used to analyze the data. The mean concentration of heavy metal in groundwater samples (both seasons) for Pb, Cd, Ni, Cr, Mn, Fe, Zn and Cu were 0.459, 0.006, 0.084, 0.016, 0.100, 0.709, 0.036, and 0.117 mg/L respectively at the Ota sampling location, while at Sagamu, the mean values of respective metals were 0.450, 0.012, 0.082, 0.016, 0.165, 0.663, 0.031, and 0.146 mg/L. The order of presence of the metals in groundwater was in the order Pb > Fe > Ni > Cr > Cd > Cu > Mn > Zn. The total hazard index (HI) of the metals in the groundwater samples showed a high risk across the different age groups. HI value (HI>1.0) demonstrates in general unfavorable non-cancer-causing impacts, in which the infants were at most serious risk. The cumulative Cancer Risk in the study areas shows a medium-extremely high risk for the analyzed metals. The calculated health risk index indicates major adverse effects on human health.

Organosulphur-modified biochar: An effective green adsorbent for removing metal species in aquatic systems

Organosulphur-modified biochar (BC) can be used as a green adsorbent for removing potentially toxic metal ions from aqueous solutions. In this study, sugarcane bagasse BCs (produced at pyrolysis temperatures from 300 to 700°C) were modified in a single-step reaction with isothiocyanate. The performance and selectivity of raw and modified BCs for removing Cd2+, Ni2+, Pb2+ and Cr3+ from mono- and multi-element aqueous solutions were investigated. The characterisation of the BCs was performed by proximate analysis, Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC-MS). The results showed that the organosulphur modification increased S and N contents on the surface of the BCs, particularly isothiocyanate groups. The maximal adsorptions were observed for raw and modified BCs produced at 700°C and pH 6. The adsorption kinetics of Cd2+, Ni2+, Pb2+ and Cr3+ before and after BC modification was best described by the pseudo-second order kinetic model. The results indicated that the removal of metal ions by modified-biochars follows the order Pb2+> Cr3+> Cd2+ ≅ Ni2+ and Cd2+> Pb2+> Ni2+≅Cr3+ for mono-element and multi-element systems, respectively. The mechanisms involved in the adsorption were physisorption, chemisorption, complexation, precipitation, and ion exchange. The presence of other metal ions in the multi-element system caused a synergistic effect on adsorption of Cr3+, Cd2+ and Ni2+ and an antagonistic effect on adsorption of Pb2+. Organosulphur-modified BC can be an effective andselective adsorbent for removing Cd2+, Ni2+, Pb2+ and Cr3+ from aqueous solutions.

Production and functionality of exopolysaccharides in bacteria exposed to a toxic metal environment

In this study, the production and compositional analysis of exopolysaccharides produced by Bacillus cereus KMS3-1 grown in metal amended conditions were investigated. In addition, the metal adsorption efficacy of exopolysaccharides (EPS) produced by KMS3-1 strain was evaluated in a batch mode. Increased production of exopolysaccharides by KMS3-1 strain was observed while growing under metal amended conditions (100 mg/L) and also, the yield was in the order of Pb(II)>Cu(II)>Cd(II)>Control. Characterization of EPS using FT-IR, XRD, and SEM analysis revealed that the EPS can interact with metal ions through their functional groups (O‒H, CH, C˭O, C‒O, and C‒C˭O) and assist the detoxification process. Further, equilibrium results were fitted with the Langmuir model and notably, the maximum adsorption capacity (Qmax) of EPS for Cd(II), Cu(II), and Pb(II) found to be 54.05, 71.42, and 78.74 mg/g, respectively. To the best of our knowledge, EPS demonstrating proficient metal adsorption was substantiated by XRD analysis in this study. Owing to good adsorbing nature, the exopolysaccharides could be used as chelating substances for wastewater treatment.

The relationship between properties of plant-based biochars and sorption of Cd(II), Pb(II) and Zn(II) in soil model systems

Plant based biochars are proposed as soil amendments to immobilize potentially toxic trace elements (PTEs), such as Cd(II), Pb(II) and Zn(II) and aid in soil restoration. However, the sorption capacity of biochar for these elements can vary widely depending on biochar nature and metal properties. Currently, there is no clear methodology to pre-screen biochars for their suitability as adsorbents for these elements. Therefore, to facilitate biochar selection for application in soil restoration, this study explored the relationships between the physico-chemical properties of five plant-based biochars and their capacity to immobilize Cd(II), Pb(II) and Zn(II). Batch experiments using synthetic soil pore water were used to assess the sorption of these elements. The sorption isotherms described by the Hill model indicated that PTE sorption capacity followed the order Pb(II) > Cd(II) >Zn(II) regardless of biochar type in mono-element systems. Preferential sorption of Pb(II) limited the immobilization of Cd(II) and Zn(II) in multi-element systems. ATR-FTIR and SEM-EDX spectroscopy studies indicated that Cd(II) and Pb(II) sorption was mediated by complexation with carboxylic groups, cation–π interactions and precipitation with phosphates and silicates, while Zn(II) sorption occurred mainly by complexation with phenolic groups and precipitation with phosphates. A high correlation (>0.8) between Electrical Conductivity, Cation Exchange Capacity, pH and sorption capacity was identified for all metals tested, highlighting the electrostatic nature of the sorption mechanisms involved. Biochars derived from herbaceous feedstock were better candidates for remediation of soil polluted with Cd(II), Pb(II) and Zn(II), rather than wood-derived biochar. Overall, this study provides evidence of the direct relationship between specific properties of plant-based biochars (pH and EC) and their suitability as adsorbents for some PTEs in soil systems.

A comparative study on the dissolution and stability of beudantite and hidalgoite at pH 2–12 and 25–45 °C for the possible long-term simultaneous immobilization of arsenic and lead

Beudantite and hidalgoite were synthesized and characterized to investigate their possible immobilization for arsenic and lead in acidic and oxidizing environments by a long-term dissolution. The synthetic beudantite [Pb0.35(H3O)0.40Fe3.09(AsO4)0.37(SO4)1.63(OH)6.00] was spherulitic pseudo-cubic crystals with nearly smooth surface. The synthetic hidalgoite [Pb0.72(H3O)2.71Al2.26(AsO4)0.93(SO4)1.07(OH)6.00] was well-formed pseudo-cubic, pseudo-cuboctahedral or pseudo-octahedral crystals. During the beudantite dissolution, the constituents were dissolved preferentially in the order of SO42− > AsO43− > Pb2+ > Fe3+ in the early 24 h and SO42− > AsO43− > Fe3+ > Pb2+ after 24 h; the dissolved concentrations exhibited a minimum of 0.0027–0.0030 mg/L Pb and 0.0248–0.0250 mg/L As. During the hidalgoite dissolution, the constituents were dissolved preferentially in the order of Pb2+ > SO42− > AsO43− > Al3+ at initial pH < 4 or AsO43−,SO42− > Al3+ > Pb2+ at initial pH > 4; the dissolved concentrations showed a minimum of 0.0055–0.0061 mg/L Pb and 0.0750–0.0810 mg/L As. From the data of the dissolution at initial pH 2 and 25 °C for 270–330 d, the ion-activity products [logˍIAP] were estimated to be −94.18 ± 0.04 for the beudantite and −73.82 ± 0.11 for the hidalgoite, respectively. The concentrations of Pb and As released in the beudantite dissolution were always lower than in the hidalgoite dissolution and arsenate appeared to be much more soluble than Pb. Beudantite was more effective for the immobilization of As and Pb than hidalgoite.

Occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia.

Industrial wastes have been increasingly discharged into water and soil, and causing environmental pollution in Ethiopia. This study examined the occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia. The composite samples of soil, water, and vegetables were collected accordingly to determine the concentration of heavy metals (Cu, Pb, Zn, Mn, and Ni) in each system during dry and wet seasons. The concentration of heavy metal was assayed using atomic absorption spectrophotometry. The data were statistically analyzed using one-way ANOVA. The heavy metal concentration was decreased in the order of Pb > Mn > Ni > Cu > Zn, Mn > Ni > Pb > Cu > Zn, and Ni > Pb > Mn > Cu > Zn in the water, soil, and vegetables in the area respectively. The variation of levels of heavy metal in the water, soil, and vegetable might be because of the effect of heavy metal speciation and valence, industry types, vegetable types and tissues, and soil. The bioconcentration factor of heavy metals was higher than that one for copper, signifying the increased probability of health risk for those who are consuming vegetables grown in the area. Thus, the government should take this into account and devise mitigation strategies through the implementation of heavy metal removal systems from contaminated water and soil, waste management strategies of recycling, centralized or decentralized treatment plant, changing of industrial residual into biogas production, and awareness creation for the society.

Heavy Metals Contamination of Soil in the Vicinity of Hawassa Industrial Zone, Ethiopia

Industrial effluents, containing heavy metals, drain directly into downstream water sources within the Hawassa Industrial Zone. These, water sources are used for irrigation, drinking water and other domestic purposes. The load of pollutants, environmental risks and potential human impacts are generally, unknown for soil in Ethiopia. Therefore, the aim of this study was to determine the extent of heavy metal pollution of soil within the Hawassa Industrial Zone and to evaluate environmental impacts using contamination factor (CF), degree of contamination (Cd), modified degree of contamination (mCd), ecological risk factor (Er), ecological risk index (ERI) and pollution load index (PLI) analyses. Seven heavy metals: Cr, Ni, Cu, Zn, As, Cd and Pb were determined in soil samples from three different sites by inductively coupled plasma mass spectrometry (ICP-MS). Average concentration of metals decreased in the order of Zn&gt;Cu&gt;Cr&gt;Ni&gt;Pb&gt;As&gt;Cd consistent with the normal order of abundance in non-polluted soils. One way ANOVA revealed significant differences (P&lt;0.05) in the concentrations of Cu, As, Cd and Pb among the sampling sites. Pearson’s correlation, principal component and cluster analyses revealed that heavy metals are originating from different sources. Within the industrial area, the CF increased in the order of Pb&lt;Cd&lt;Zn&lt;As&lt;Cu&lt;Cr&lt;Ni. The result of Cd revealed that there was considerable to very high contamination of the soil. The mCd index showed moderate contamination of the soils. The Er increased in the order of Zn&lt;Cr&lt;Pb&lt;Cu&lt;Ni&lt;As&lt;Cd and the result of the ERI value revealed considerable ecological risk for the soils. Overall, the study showed that the soils within the Hawassa Industrial Zone are highly contaminated with heavy metals. Therefore, regular monitoring of heavy metals concentration in soil and policy interventions with respect to waste disposal are recommended.&#x0D; Keywords: Heavy metals, potential ecological risks, pollution load index, soil

Bioaccumulation of metals in mangroves and salt marshes collected from Tuticorin coast of Gulf of Mannar marine biosphere reserve, Southeastern India

Three species of mangroves and six species of salt marshes were collected from various locations along the Tuticorin coast for the estimation of metals like Cu, Cd, Pb, and Zn. The bioaccumulation of metals in mangroves is in the order of Cu > Pb > Zn > Cd, and the season-wise accumulation was higher in monsoon followed by summer, post-monsoon, and pre-monsoon seasons. The accumulation of metals in mangroves showed higher in Rhizophoraapiculata followed by Avicenniamarina, and Rhizophoramucronata. The concentration of metals in salt marshes is in the order of Pb > Zn > Cu > Cd, and the species-wise accumulation showed in the order of Suaeda maritime > Ipomoea sp. > Suaeda sp. > Spinifix littoreous > Sesuvium portacastrum > Ipomoea pes-capras. BAF in salt marhes and mangroves is as Cd < Pb < Cu < Zn and Cd < Cu < Pb < Zn, respectively.

Monitoring spatially resolved trace elements in polar bear hair using single spot laser ablation ICP-MS

Elements and compounds circulating in the body are incorporated into hair as it grows. Because of this, hair analyses are increasingly being incorporated in investigations of temporal trends in e.g. hormones and diet in wildlife species such as polar bears (Ursus maritimus).For this study, guard hair (GH; mean length 62 mm) and foreleg guard hair (FGH; mean length 164 mm) were collected from 15 adult male polar bears in western Hudson Bay, Canada. Our aim was to quantify the trace elements arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), selenium (Se), strontium (Sr), and zinc (Zn) every 3 mm in GH and FGH using laser ablation inductively coupled plasma mass spectrometry (laser ablation ICP-MS).Quantitative data was obtained at spatial scales as small as 50 μm – the smallest laser spot diameter used. Mean trace element concentrations increased in the order Pb < As < Cd < Se < Hg < Cu < Sr < Fe < Zn for both GH and FGH (pooled across all individuals). However, mean trace element concentrations were all significantly different between GH and FGH, except for Hg. Hg concentration varied along the length of both GH and FGH; each bear exhibited a unique pattern in Hg variation along the hair. For the remaining eight trace elements, the most common pattern was that of smaller fluctuations near the base of the hair, followed by an increase towards the tip. These fluctuations in trace element concentrations were likley related to hair growth and temporal changes. In this pilot study, we found quantifying trace elements in polar bear hair using laser ablation ICP-MS to be a promising monitoring technique across multiple temporal scales.

Superselective Removal of Lead from Water by Two-Dimensional MoS2 Nanosheets and Layer-Stacked Membranes.

Point-of-use (POU) devices with satisfactory lead (Pb2+) removal performance are urgently needed in response to recent outbreaks of lead contamination in drinking water. This study experimentally demonstrated the excellent lead removal capability of two-dimensional (2D) MoS2 nanosheets in aqueous form and as part of a layer-stacked membrane. Among all materials ever reported in the literature, MoS2 nanosheets exhibit the highest adsorption capacity (740 mg/g), and the strongest selectivity/affinity toward Pb2+ with a distribution coefficient Kd that is orders of magnitude higher than that of other lead adsorption materials (5.2 × 107 mL/g). Density functional theory (DFT) simulation was performed to complement experimental measurements and to help understand the adsorption mechanisms. The results confirmed that the cation selectivity of MoS2 follows the order Pb2+ > Cu2+ ≫ Cd2+ > Zn2+, Ni2+ > Mg2+, K+, Ca2+. The membrane formed with layer-stacked MoS2 nanosheets exhibited a high water flux (145 L/m2/h/bar), while effectively decreasing Pb2+ concentration in drinking water from a few mg/L to less than 10 μg/L. The removal capacity of the MoS2 membrane is a few orders of magnitude higher than that of other literature-reported membrane filters. Therefore, the layer-stacked MoS2 membrane has great potential for POU removal of lead from drinking water.