Geochemical investigation of potentially harmful elements in household dust from a mercury-contaminated site,the town of Idrija (Slovenia)

A comprehensive geochemical investigation of potentially harmful elements (PHEs) in household dust from the town of Idrija (Slovenia), once a world-famous Hg mining town that is now seriously polluted, was performed for the first time. After aqua regia digestion, the content of mercury (Hg), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb) and zinc (Zn) was measured. PHE-bearing particles were recognised and observed by scanning electron microscopy and energy-dispersive spectrometry before and after exposure to simulated stomach acid (SSA). Mercury binding forms were identified by Hg thermal desorption technique and gastric bioaccessible Hg was estimated after SSA extraction by ICP-MS. With regard to rural and urban background values for Slovenia, high Hg content (6–120 mg/kg) and slightly elevated As content (1–13 mg/kg) were found. Mercury pollution is a result of past mining and ore processing activities. Arsenic content is potentially associated with As enrichment in local soils. Four Hg binding forms were identified: all samples contained Hg bound to the dust matrix, 14 samples contained cinnabar, two samples contained metallic Hg (Hg⁰), and one sample assumingly contained mercury oxide. After exposure to SSA, Hg-bearing phases showed no signs of dissolution, while other PHE-bearing phases were significantly morphologically and/or chemically altered. Estimated gastric Hg bioaccessibility was low (<0.006–0.09 %), which is in accordance with identified Hg binding forms and high organic carbon content (15.9–31.5 %) in the dust samples.     

A study on toxic and essential elements in rice from the Republic of Kazakhstan: comparing the level of contamination in rice from the European Community

Selected toxic elements (total As, Cd, Cr, Hg, Pb, Sr, U and V) and essential elements (Co, Cu, Fe, Mn and Zn) were analyzed using an inductively coupled plasma mass spectrometry (ICP-MS) in unpolished and milled rice collected from Kazakhstan and milled rice from Spain and Portugal to evaluate the potential health risk to the population. Arsenic species (arsenite, arsenate, arsenobetaine, dimethylarsinate and monomethilarsonate) were analyzed using HPLC-IC-MS. From 146 samples analyzed, none of them exceeded the maximum limit set by the European Legislation for Cd or Pb or values recommended by the Codex Alimentarius. Concentrations of Sr, U and V were below LOD and those of Hg, Pb, Co and Cr between <LOD and 0.54 mg/kg (highest concentration of Cr) in milled rice. Portuguese rice samples contained the highest mean concentration of As, Hg, Pb, Co, Cr, Cu, Mn and Zn. The highest mean of arsenobetaine (0.001 mg/kg), dimethylarsinate (0.27 mg/kg) and monomethilarsonate (0.02 mg/kg) was found in Spanish rice and that of arsenite (0.30 mg/kg) in Kazakh rice. Inorganic As in samples from Kazakhstan was above the ML (0.2 mg/kg) proposed by FAO/WHO, but in seven samples from Spain and in four from Portugal were above the limit. The estimated weekly intake of total or inorganic As(III, V), Cd, Hg and Pb for rice consumption by Kazakh, Spanish and Portuguese adults and children was lower than the provisional tolerable weekly intake established by Joint FAO/WHO Expert Committee on Food Additives and the European Food Safety Authority.

     

The influence of arsenic speciation (AsIII & AsV) and concentration on the growth, uptake and translocation of arsenic in vegetable crops (silverbeet and amaranth): greenhouse study

We examined arsenic (As) uptake by vegetable crops (amaranth, Amaranthus gangeticus, and silverbeet, Beta vulgaris) as affected by As speciation (As^III and As^V) and their concentrations in nutrient solution. Amaranth and silverbeet were grown in a nutrient solution containing four levels of arsenate (As^V): 0, 1, 5, and 25 mg As/l and three levels of arsenite (As^III): 0, 5, 10 mg As/l. Both As^V and As^III are phytotoxic to these crops with the latter being five times more toxic. Amaranth treated with As^III exhibited As toxicity symptoms within 48 h of exposure and was close to death within 1 week. However, As^V treatment did not show clear toxicity symptoms other than wilting and yield reduction at the highest dose rate of 25 mg As^V/l. The main mechanism used by vegetable crops to tolerate As^V is probably avoidance—limiting As transport to shoots and increasing As accumulation in the root system. When As^V was added to the nutrient solution, the uptake of As in shoots increased and, at the highest dose (25 mg As^V/l), 60 μg As/g DW (3.6 mg/kg FW) accumulated in the edible portion, which exceeds the WHO recommended limit for food stuffs (2 mg/kg FW) as the water contents of the crops were 94%. It is therefore important to determine the nature of the As species and their bio-accessibility. Iron treatment with 0.5 mg NaFe(III)EDTA/l dose decreased silverbeet As uptake by 45% given its affinity to bind As at the root surface or root rhizosphere and so restrict As translocation to the shoots.     

珠三角某垃圾焚烧厂周边植物叶片汞含量空间格局影响因素影响因素

为研究珠三角某城市生活垃圾焚烧厂周边汞污染空间格局及影响因素,于2014年1月,采集了马占相思、荔枝和芒萁等优势种的叶片样品192份,并同步采集相应表层土壤样品64份,采用冷原子吸收法测定样品总汞含量,并运用ADMS模型对2013年大气汞年均浓度进行模拟,分析了植物叶片汞含量与土壤和大气汞浓度之间的关系。结果表明,植物叶片的汞含量范围为0.0029~0.1741 mg·kg-1,荔枝叶片汞含量最高,为(0.0766±0.0395)mg·kg-1,其次为芒萁((0.0599±0.0370)mg·kg-1)和马占相思((0.0556±0.0396)mg·kg-1)。植物叶片汞含量与土壤汞含量无显著相关性,而受风向和距污染源的距离影响显著,与ADMS模拟的大气年均汞浓度存在显著相关性。研究表明,植物叶片汞含量变化与烟气扩散浓度的空间分异格局基本吻合,叶片对大气中汞的吸收在植物与环境的汞交换中占据主导地位,对叶片的生物监测可以反映城市生活垃圾焚烧厂汞排放对生态环境的实际影响。     

Urban sediment contamination in a former Hg mining district,Idrija, Slovenia

Road sediments from gully pots of the drainage system and stream sediments from local streams were investigated for the first time in the urban area of Idrija town, the central part of the second largest and strongly contaminated Hg mining district in the world. Hg concentrations in road sediments were lower than in stream sediments. They ranged from 16 to 110 mg/kg (Md = 29 mg/kg) for <0.125 mm particles and from 7 to 125 mg/kg (Md = 35 mg/kg) for <0.04 mm particles, while Hg concentrations in stream sediments ranged from 10 to 610 mg/kg (Md = 95 mg/kg) for <0.125 particles and from 10 to 440 mg/kg (Md = 105 mg/kg) for <0.04 mm particles. High Hg loadings in stream sediments were successfully linked with identified mercury sources (rocks containing mercury ore, areas of former ore roasting sites, ore residue dumps), because they are located in the drainage areas of streams, from which the sediments were collected. Links between Hg loadings in road sediments and identified mercury sources were not recognized. Solid phases of Hg were determined by thermo-desorption technique and are similar for both types of sediments. Results show the occurrence of three different forms: elemental mercury, mercury bound to matrix components and cinnabar. Approximately 50 % of Hg in samples consist of non-cinnabar fractions. This is important, since they are potentially bioavailable. An interesting new discovery according to previous research of environmental media from Idrija area by solid-phase Hg thermo-desorption technique is that elemental mercury was determined in almost all investigated sediments in minor amounts (Md = 3 %).     

Geochemical distribution of trace element concentrations in the vicinity of Boroo gold mine,Selenge Province,Mongolia

The environmental impacts of Boroo gold mine project in Mongolia was evaluated by chemical characterization of trace element concentrations in water, soils and tailing dam sediment samples. The results showed that concentrations of B, Cd, Ni and Se in the water samples were within the accepted levels of the Mongolia water quality standard (MNS4586: 1998). However, the concentrations of Al, As, Cu, Mn, Fe, Pb, U and Zn were higher than the maximum allowable concentration especially in the monitoring and heap leach wells. The average concentrations of As, Cd, Cu, Ni, Pb and Zn in the tailing dam sediment were 4419, 58.5, 56.0, 4.8, 20.6 and 25.7 mg/kg, respectively. Generally, arsenic and heavy metals in the soil samples were within the acceptable concentrations of the soil standard of Mongolia (MNS 5850: 2008). The chemical characterization of As solid phase in tailing dam sediment showed that the majority of As were found in the residual fraction comprising about 74% of total As. Assessing the potential risk to humans, simple bioavailability extraction test was used to estimate bioavailability of arsenic and heavy metals, and the concentrations extracted from tailing dam sediment were; 288.2 mg/kg As, 7.2 mg/kg Cd, 41.1 mg/kg Cu, 13.5 mg/kg Pb, 4.7 mg/kg Ni and 23.5 mg/kg Zn, respectively. From these results, the Boroo gold mine project has presently not significantly impacted the environment, but there is a high probability that it may act as a source of future contamination.     

华东地区鳜肌肉重金属含量现状与风险分析

为了解我国华东地区鳜肌肉重金属含量现状,采集华东地区(江西南昌,安徽池州、滁州,江苏南京、扬州,浙江建德等)10个采样点野生鳜和池塘主养、池塘套养鳜样本共60份,采用原子荧光光谱分析法(AFS)、石墨炉原子吸收法(GFAAS)测定鳜背部肌肉中铬(Cr)、镉(Cd)、无机砷(As)、汞(Hg)和铅(Pb)等5种重金属的含量,评估其食用安全性与健康风险。结果表明,肌肉中Cd、Cr、Pb、As和Hg的总检出率为98.67%,总超标率为11.67%;其中,Pb、Cd和As超标样,分别占总样本量的28.33%、15%和15%,超标浓度为(0.612±0.111)、(0.181±0.031)和(0.474±0.035) mg·kg~(-1),71.43%的超标样分布于野生鳜群体;Cr、Hg的检出含量均低于我国鱼类水产品重金属的最高限量标准(GB 2762—2017)。3种养殖方式的鳜肌肉中重金属含量分布具有相似的规律(Pb>As>Cr=Cd>Hg),野生鳜肌肉中重金属含量高于人工养殖鳜,池塘主养鳜与池塘套养鳜之间无明显差异。食用安全性评价结果显示,目前,华东地区鳜达到国家标准的限量要求,仅Pb、As含量稍高,分别占周可耐受摄入量(PTWI)的14.42%和21.54%。健康风险评价结果显示,所有鳜样均未超过国际辐射防护委员会(ICRP)推荐的最大可接受水平(5×10~(-5)a~(-1))。野生鳜食用安全性低于人工养殖鳜,健康风险高于人工养殖鳜。上述研究结果为鳜水产品安全性评价与健康养殖提供了基础数据。     

Fish as an indicator of aquatic environment: Multielemental neutron activation analysis of nutrient and pollutant elements in fish from Indian coastal areas

Fish is the main food in coastal areas and its analysis for toxic metals has been used as an indicator of the pollution status of the aquatic environment. Several different fish species from the three Indian coasts, Visakhapatnam in the east, Mumbai in the west and Mangalore in the south west and also inland freshwater fish from Nagpur in the central region for comparison were analyzed for up to 20 elements (As, Au, Ba, Br, Cl, Co, Cr, Cu, Fe, Hg, K, Mn, Na, P, Rb, Sb, Sc, Se, Sr, Zn) by instrumental neutron activation analysis (INAA). Dried fish samples in powdered form were irradiated with thermal neutrons in a nuclear reactor followed by high resolution gamma ray spectrometry at different intervals. Several Reference Materials (RMs) of biological origin were analyzed for quality assurance and data validation. Elemental contents in different fish species vary in a wide range depending on the species, its size, location, and aquatic environment. Fish from Mangalore showed highest mean contents of Cr (14.8?±?29.9?µg?g^?1), Cu (1005?±?643?µg?g^?1) and Sb (849?±?888?ng?g^?1) whereas those from Mumbai exhibited highest Hg (2066?±?2146?ng?g^?1) and P (20.3?±?4.63?µg?g^?1) but lowest Cu (6.30?±?3.10?µg?g^?1) contents. Fish from all the regions showed significant amounts of nutrient elements such as Na, K, P, Mn, Fe, Se and Zn as well as some pollutant elements (Br, Cr, Sb, Hg). No regularity in variation of elemental contents with the size was observed. Prawn (Panaeus latisulcatus), a popular fish species from four different regions showed wide variation in elemental contents of Cr, Mn, Fe, Zn, Se, P including toxic pollutants, Sb and Hg. An attempt has been made to calculate daily dietary intake (DDI) for some nutrient elements from Indian fish. Elemental data for Cr, Cu, Fe, Hg, Se, and Zn have been compared with those from other fish exporting countries.     

Simultaneous measurements of arsenic and sulfide using diffusive gradients in thin films technique (DGT)

Diffusive gradients in thin films technique (DGT) is a dynamically passive sampling technique which has been applied increasingly to the environmental monitoring field. In the preliminary period, the DGT with zirconium hydroxide-silver iodide as the binding phase (ZrO-AgI DGT) has been developed for the determination of sulfide (S(II)). On this basis, this paper developed its determination method for inorganic arsenite (As(III)) to further realize the simultaneous and high-resolution measurements of labile inorganic As and S(II) in sediments. ZrO-AgI binding gel had a strong ability in adsorbing and fixing As(III), showing a linear increase in the initial 12.5 min. After saturation of S(II) on ZrO-AgI binding gel, the adsorption rate and adsorption capacity of As(III) reduced by 8 and 14%, respectively. A stable elution rate (89.1 ± 2.2%) was obtained by extraction of As(III) on the binding gel using a mixture solution of 1.0 M NaOH and 1.0 M H₂O₂ (1:1). The DGT capacity of As(III) determined by the ZrO-AgI DGT was 23.6 μg cm^?2. DGT uptakes of As(III) were independent of pH (4.0–9.0) and ionic strength (0.01–100 mM), and they did not interfere with each other during the uptake process. Simultaneous measurements of labile As and S(II) in four sediment cores of Taihu Lake (China) with ZrO-AgI DGT showed that they had similarly vertical distributions in the top 16-mm layer in one core and in the whole profile up to the 35 mm depth in two cores. It likely reflected a simultaneous release of As and S(II) in sediments by synchronous reduction of As-hosted oxidized iron and sulfate, respectively. The simultaneous decreases of labile As and S(II) from their co-precipitation (e.g., As₂S₃) were not obvious in deeper sediment layer through the measurement with ZrO-AgI DGT.     

Accumulation and transfer of Hg, As, Se, and other metals in the sediment-vegetation-crab-human food chain in the coastal zone of the northern Brazilian state of Pará (Amazonia)

The high consumption of crabs (Ucides cordatus) stimulated interest in the present study on the northern coast of Brazil, which encompasses a preserved area of mangrove forest. The objective was to describe and quantify the transfer of metals from the muddy sediments to the leaves of the Rhizophora mangle, and thence the crabs and humans. The samples were collected along two transects, while samples of hair were obtained from local habitants. The pH, interstitial salinity, Eh (mV) were measured, the granulometry and mineralogical and multi-element chemical analyses were run, and the organic material determined. The sediments are silty-clayey, composed of quartz, kaolinite, iron oxides, and illite, as well as smaller portions of smectite, pyrite, halite, and high levels of SiO₂ (56.5 %), Al₂O₃ (18.5 %), and Fe₂O₃ (7 %). The elements Zn, Sr, As, and Zr are concentrated in the leaves, while the bioaccumulation of Zn, Se, Sr, and As was recorded in the crabs, of which, Se is the most concentrated in the tissue of the muscles and the hepatopancreas. The concentrations of nutrient and toxic elements were similar in all age groups (hair samples), with only Hg presenting an increasing concentration between infants and adults. The highest rates of transfer were recorded for the elements Zn and Se in the crabs and Hg in leaves and hair. The accumulation of metals in the leaves and crabs reflects the chemical composition of the sediments and low rates of sediment-vegetation-crab transfer, with the exception of Hg, which accumulated in the hair.     

Exposure assessment for mercury from consumption of marine fish in Iran

Seven species of marine fish in the Persian Gulf and three species of marine fish in the Caspian Sea were collected from the local wholesale market in Mashhad, Iran. The mercury (Hg) concentration in muscle samples was determined by atomic absorption spectrophotometry. High total Hg concentration was found in Anchovy sprat (2.04 ± 1.23 µg g^?1) and Whitecheek shark (1.26 ± 1.85 µg g^?1) and the lowest content was detected in common carp (0.24 ± 0.24 µg g^?1) and Caspian salmon (0.25 ± 0.08 µg g^?1). The mean Hg content in all samples was 0.91 ± 1.07 µg g^?1. All samples of Persian Gulf and one sample of Caspian Sea had mean Hg concentration above 0.5 µg g^?1, the level established by joint FAO/WHO on Food Additives. Results showed that the estimated weekly intake of total Hg by a 60 kg adult is below the provisional tolerable weekly intakes recommended by joint FAO/WHO on Food Additives. For prevention of health risks, populations in Iran need to consume fish in moderate amounts.     

Long-distance transport of Hg, Sb, and As from a mined area, conversion of Hg to methyl-Hg, and uptake of Hg by fish on the Tiber River basin, west-central Italy

Stream sediment, stream water, and fish were collected from a broad region to evaluate downstream transport and dispersion of mercury (Hg) from inactive mines in the Monte Amiata Hg District (MAMD), Tuscany, Italy. Stream sediment samples ranged in Hg concentration from 20 to 1,900 ng/g, and only 5 of the 17 collected samples exceeded the probable effect concentration for Hg of 1,060 ng/g, above which harmful effects are likely to be observed in sediment-dwelling organisms. Concentrations of methyl-Hg in Tiber River sediment varied from 0.12 to 0.52 ng/g, and although there is no established guideline for sediment methyl-Hg, these concentrations exceeded methyl-Hg in a regional baseline site (<0.02 ng/g). Concentrations of Hg in stream water varied from 1.2 to 320 ng/L, all of which were below the 1,000 ng/L Italian drinking water Hg guideline and the 770 ng/L U.S. Environmental Protection Agency (USEPA) guideline recommended to protect against chronic effects to aquatic wildlife. Methyl-Hg concentrations in stream water varied from <0.02 to 0.53 ng/L and were generally elevated compared to the baseline site (<0.02 ng/L). All stream water samples contained concentrations of As (<1.0–6.2 μg/L) and Sb (<0.20–0.37 μg/L) below international drinking water guidelines to protect human health (10 μg/L for As and 20 μg/L for Sb) and for protection against chronic effects to aquatic wildlife (150 μg/L for As and 5.6 μg/L for Sb). Concentrations of Hg in freshwater fish muscle ranged from 0.052–0.56 μg/g (wet weight), mean of 0.17 μg/g, but only 17 % (9 of 54) exceeded the 0.30 μg/g (wet weight) USEPA fish muscle guideline recommended to protect human health. Concentrations of Hg in freshwater fish in this region generally decreased with increasing distance from the MAMD, where fish with the highest Hg concentrations were collected more proximal to the MAMD, whereas all fish collected most distal from Hg mines contained Hg below the 0.30 μg/g fish muscle guideline. Data in this study indicate some conversion of inorganic Hg to methyl-Hg and uptake of Hg in fish on the Paglia River, but less methylation of Hg and Hg uptake by freshwater fish in the larger Tiber River.     

Electro-remediation of tailings from a multi-metal sulphide mine: comparing removal efficiencies of Pb,Zn, Cu and Cd

Sulphidic mine tailings characterised by high concentrations of heavy metals (Pb 3532?±?97?mg/kg, Zn 8450?±?154?mg/kg, Cu 239?±?18?mg/kg and Cd 14.1?±?0.3?mg/kg) and abundant carbonate (17%) were subjected to eight lab-scale electrodialytic remediation (EDR) experiments to investigate the influence of current density, treatment time and particle size on removal efficiency. Pb and Cu removal improved when increasing current density, while Zn and Cd removal did not. In contrast Zn and Cd removal improved by grinding the tailings, while Pb and Cu removal did not. At the highest current density (1.2?mA/cm²), 94%, 75%, 71% and 67% removal of Pb, Zn, Cu and Cd could be achieved, respectively, on grinded tailings in 28 days. Sequential chemical extraction made before and after EDR revealed larger oxidisable fractions of Zn, Cu and Cd, representing large fractions of sulphides, which was likely to be the main barrier to be removed as efficiently as Pb. This was in accordance with acid/base extraction tests in which Pb showed high solubility at both high and low pH (up to 65% and 86% of extraction, respectively), while considerable extraction of Zn (55%) happened only at low pH; and very limited extraction (<20%) of Cu and Cd occurred at any pH.     

Bioconcentration factors of mercury by Parasol Mushroom (Macrolepiota procera)

To examine bioconcentration factors (BCFs) of mercury by Parasol Mushroom (Macrolepiota procera) roughly similarly sized (a cap diameter) fruiting bodies of this fungus and underlying soil (0–10 cm) samples were collected at 15 sites in Poland between 1995 and 2003. The total mercury content of the individual caps and stipes of Parasol Mushroom ranged from 0.05 to 22 mg Hg/kg dry matter (d.m.) and from 0.05 to 20 mg Hg/kg d.m., while the means were from 1.1 to 8.4 mg Hg/kg d.m. and from 0.83 to 6.8 mg Hg/kg d.m., respectively. The caps generally contained higher concentrations of mercury when compared to stipes, and the means of the cap to stipe mercury concentration quotient ranged from 1.3 to 4.6. The range of mercury concentration in topsoil samples collected at the sites where the fruiting bodies were collected was from 0.01 to 0.54 mg/g d.m. (means ranged from 0.022 to 0.36 mg/g d.m.). The BCFs factors for total mercury varied from 0.52 to 470 for individual caps and 0.52 to 360 for stipes, while average values, depending on the site, were from 16 to 220 and from 7.6 to 130 for caps and stipes, respectively.     

Toxicity potential of Grassate® a non-selective herbicide on snails (Achachatina marginata) and earthworms (Aporrectodea longa)

The application of herbicides in agricultural practices may pose certain toxic effects on non-target species including molluscs (snails), earthworms and other soil-dwelling organisms, which would in turn put the lives of humans at great risk. This study considered the lethal and sublethal effects of Grassate®, a non-selective glyphosate-based herbicide on snails (Archachatina marginata) and earthworms (Aporrectodea longa) with regards to ecotoxicological risk assessment. The lethal concentration LC₅₀ for the test chemical averaged at 1.731?±?0.05 and 3.045?±?0.08?mg?kg^?1 for snails and earthworms, respectively. There was decrease in growth and biomass with increased concentration for the species. Growth inhibition of 11–38% in size and 7–43% in length was obtained for earthworms while 26–65% reduction in weight was reported for snails. Using the ecotoxicological risk assessment matrix, the herbicide was classified as D 4 (A; P; E) or 16 (A; P; E), which could be considered as high risk to animals, plant and the environment. Thus, if these herbicides are used uncontrollably and unregulated, further consequence could lead to harmful effects on humans who feed on snails, a rich source of protein and depend on earthworms for nutrient.     

Arsenic speciation in rice consumed in south-western Nigeria,and estimation of dietary intake of arsenic species through rice consumption

This study determined concentrations and speciation of arsenic (As) in rice samples obtained from the cities of Akure, Ore, Ondo and Ikare in Ondo State, south-western Nigeria. The estimated dietary intake of As from rice consumption for total As and the identified As species were compared with the As benchmark dose lower confidence limit. Analyses of rice from the four cities identified three As species: inorganic As, monomethylarsonic, acid and dimethylarsinic acid. Concentrations of total As and the As species differed significantly across the sampling locations (by a factor of 2.5 for total As). Mean levels (±S.D.) were 58.8 ± 0.7 µg/kg total As, 47.0 ± 0.6 µg/kg inorganic As, 0.33 ± 0.03 µg/kg monomethylarsonic acid, and 11.5 ± 0.1 µg/kg dimethylarsinic acid. The estimated mean dietary intakes were 4.1 µg/d total As, 3.3 µg/d inorganic As, 0.02 µg/d monomethylarsonic acid, and 0.8 µg/d dimethylarsinic acid. These values are below the benchmark dose lower confidence limit and comparable to, or lower than, those reported for other countries. Thus, consumption of rice cultivated in south-western Nigeria does not appear to have inherent As-associated health risks.     

The role of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in arsenic bioleaching from soil

Bioleaching of As from the soil in an abandoned Ag–Au mine was carried out using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A. ferrooxidans is an iron oxidizer and A. thiooxidans is a sulfur oxidizer. These two microbes are acidophilic and chemoautotrophic microbes. Soil samples were collected from the Myoungbong and Songcheon mines. The main contaminant of the soil was As, with an average concentration of 4,624 mg/kg at Myoungbong and 5,590 mg/kg at Songcheon. A. ferrooxidans and A. thiooxidans generated lower pH conditions during their metabolism process. The bioleaching of As from soil has a higher removal efficiency than chemical leaching. A. ferrooxidans could remove 70 % of the As from the Myoungbong and Songcheon soils; however, A. thiooxidans extracted only 40 % of the As from the Myoungbong soil. This study shows that bioleaching is an effective process for As removal from soil.     

Assessment of radon concentration and heavy metal contamination in groundwater of Udhampur district,Jammu &amp; Kashmir,India

Radon concentration was measured in water samples of 41 different locations from Udhampur district of Jammu & Kashmir, India, by using RAD7 and Smart RnDuo monitor. The variation of radon concentration in water ranged from 1.44 ± 0.31 to 63.64 ± 2.88 Bq L^?1, with a mean value of 28.73 Bq L^?1 using RAD7 and 0.64 ± 0.28 to 52.65 ± 2.50 Bq L^?1, with a mean value of 20.30 Bq L^?1 using Smart RnDuo monitor, respectively. About 17.07% of the studied water samples recorded to display elevated radon concentration above the reference range suggested by United Nation Scientific Committee on the Effects of Atomic Radiations (UNSCEAR). The mean annual effective dose of these samples was determined, and 78.95% samples were found to be within the safe limits set by World Health Organisation (WHO) and European Council (EU). The study revealed good agreement between the values obtained with two methods. Heavy metals (Zn, Cd, Fe, Cu, Ni, As, Hg, Co, Pb and Cr) were determined in water samples by microwave plasma atomic emission spectrometer, and their correlation with radon content was also analysed.     

Heavy metal pollution in Suva harbour sediments,Fiji

In Fiji, contamination of the coastal environment by heavy metals is proving to be a real concern. This work reports for the first time analyses carried out on an extensive basis, to ascertain the extent of anthropogenic contamination by heavy metals in the <0.063 mm surface sediments of Suva harbour. Sediment samples from 40 sites selected within the harbour were collected and analysed for five heavy metals. The levels of the metals range from 21.4 to 143.0 ± 0.1 mg/kg Cu, 1.40 to 4.87 ± 0.07 wt.% Fe, 22.1 to 93.5 ± 0.3 mg/kg Pb, 40.2 to 269.0 ± 0.3 mg/kg Zn and 1.1 to 2.6 ± 0.2 mg/kg Sn. With reference to the pristine area of the Great Astrolabe, in Kadavu, the acquired data from the harbour are indicative of heavy metal pollution. This could be attributed to the numerous industrial and commercial activities at Wailada and Walu Bay industrial areas, the municipal dump located at the Suva foreshore and the Suva wharf. The pollution is further compounded by the high population density in Suva city.     

Major and minor element contents of calabash clay (nzu) from Abia State,Nigeria: evaluation of potential intake benefits and risks

Major and trace elements were determined in nzu (calabash clay) from Abia State, Nigeria, by atomic absorption spectrophotometry. Mean calcium content was 1900 ± 100 mg/kg dry weight, followed by Na 1400 ± 96, Fe 1500 ± 480, K 260 ± 150, and Mg 100 ± 48 mg/kg. The mean concentration of Zn was 35 ± 5, Cu 16 ± 2.0, Mn 17 ± 5.0, Cr 10 ± 1.0, Ni 9.0 ± 2.0, Cd 4.3 ± 1.7, Co 3.9 ± 1.1, and Pb 3.0 ± 0.8 mg/kg. The contents of Ba and V were <0.4 mg/kg. The mean Pb content was higher than the WHO safe limit (0.4 mg/kg) and EU (1 mg/kg) limit for food. Estimates of daily intake of Cd, Cr, Fe, and Ni upon consuming 30–80g of nzu were above the recommended daily intake values. The Ba, Ca, Co, K, Mg, Na, and Zn contents should not exceed the recommended daily intake while Cd, Ni, and Pb would pose health risks, especially in pregnancy. The total target hazard quotient indicated potential health risks to consumers.