High Concentrations Of As Research Articles

Concentrations and health risk assessment of trace elements in animal-derived food in southern China.

This study aimed to investigate the levels of trace elements in animal-derived food in Shenzhen, Southern China. The concentrations of 14 trace elements (Cd, Hg, Pb, As, Cr, Cu, Fe, Zn, Mn, Mo, Ni, Co, Se and Ti) in a total of 220 meat samples, collected from the local markets of Shenzhen were determined. Cu, Fe and Zn were the major elements, with concentrations approximately 2-3 orders of magnitude higher than those of other elements. However, the daily intakes of Cu, Fe and Zn merely via the consumption of the meat products were lower than the recommended nutrient intake values provided by the 2013 Chinese Dietary Guide. Among the non-essential trace elements, Cd was accumulated in animal viscera, and the concentration ratios of chicken gizzard/chicken, chicken liver/chicken, pig kidney/pork and pig liver/pork were 41.6, 55.2, 863 and 177, respectively. In addition, high concentrations of As were found in aquatic products, especially in marine fish. The concentration of As in marine fish was slightly higher than the limits recommended by China, USA and Croatia. The health risk assessment of trace elements through the consumption of meat products by adult residents in Shenzhen was evaluated by using the target hazard quotient (THQ) method. The total THQ was greater than 1, implying a potential health risk. Approximately 66% of total THQ values, mainly from As, were from the consumption of aquatic products.

Hydrogeochemistry of thermal groundwaters in the Serbian crystalline core region

Geochemical exploration has been applied for studying thermal groundwater characteristics in the Serbian crystalline core region. Within this hydrogeological region, thermal groundwater with temperature higher than 20°C occurs at seven locations. The maximum discharge temperature of the thermal groundwater is 105°C which is the highest groundwater temperature encountered in Serbia. Geothermal reservoirs are present within andesite, schist, grus (the fragmental products of in-situ granular disintegration granite), marl and sandstone.Based on the concentrations of the major elements all of the water samples are of HCO3–Na to SO4–Na type. An elevated content of F, B, Ge and Rb is observed, while some samples also exhibit higher concentrations of As, Be, Cs, Ga, Ge, Li, V and W, and one has elevated concentrations of Nb, Zr and heavy rare earth elements (HREE). The groundwater is neutral to alkaline with TDS of 130–3822mg/L.Making use of various geothermometers, it was estimated that the temperatures in the selected aquifers of the Serbian crystalline core range from 45 to 146°C.Activity concentration of 222Rn ranges from 10.4±0.9 to 104±15Bq/L and is higher in groundwater that is in contact with schist and along faults, while 226Ra has a smaller activity concentrations, within the range of 0.21±0.09 to 0.48±0.18Bq/L.

Arsenic and metals mobility in soils impacted by tailings at Zimapán, México

Mining wastes may cause important environmental impacts in soil, water, and air due to their high metals and arsenic contents. The aim of this work was the assessment of the mobility of arsenic and several heavy metals in soils located near different types of tailing heaps in the town of Zimapan, Mexico. One hundred twenty soil samples were collected nearby to three tailing heaps, one oxidized presenting a red color (RT), and two with gray wastes (OSM and NSM) but with different age, during the dry and rainy seasons at the surface and to 40 cm depth, as well as to different distances from the deposits. Arsenic, Cd, Cu, Fe, Mn, Pb, V, and Zn total concentrations were determined; in addition, geochemical phase distribution of As, Cu, Mn, and Zn in selected samples was determined by sequential extraction. Concentrations were measured by graphite furnace atomic absorption spectrometry and inductively coupled plasma. To interpret the results, statistical analyses were performed. All samples presented high As concentrations reaching more than 50,000 mg kg−1 close to OSM tailings, although the highest concentrations in the available fractions were measured in NSM impacted soils. Arsenic and metals concentrations exceeded the screening limits recommended for industrial sites. In samples influenced by OSM tailings, most of the elements analyzed were in the residual fraction, whereas in NSM and RT they were mostly in the organic and sulfide fractions and in the Fe and Mn oxides fractions, respectively. Larger concentrations of As and metals than those allowed by the screening values in Canada and the Netherlands were measured in the residential area representing a health threat for the inhabitants and the environment. Acid mine drainage, water, and wind erosion of tailings have polluted nearby soils. Higher concentrations of As and metals were measured during the rainy season in gray tailings impacted soils and during the dry season in red tailings, showing both deposit types’ different mobility. Elements fractionation in soils depends mainly on tailings characteristics. Low metals and As proportions were found in the fraction with the highest mobility. Metals and arsenic are more stable in soils impacted by gray tailings, mainly in the organic and sulfides and residual fractions, while in RT, most are linked to Fe and Mn oxyhydroxides. Polluted soils in residential areas constitute a health hazard. Remedial actions must be taken to stop the population exposure.

Concentrations of 18 Elements in Muscle, Liver, Gills, and Gonads of Sichel (Pelecus cultratus), Ruffe (Gymnocephalus cernua), and European Perch (Perca fluviatilis) in the Danube River near Belgrade (Serbia)

The analysis of 18 elements in muscle, liver, gills, and gonads of sichel (Pelecus cultratus), ruffe (Gymnocephalus cernua), and European perch (Perca fluviatilis), caught at a polluted segment of the Danube River near Belgrade, was carried out with the aim to expand the knowledge about the ecotoxicology of these species for monitoring purposes and the possible impact on human health. Generally, the elemental concentration significantly differed between species and tissues (p < 0.0001), and a statistical interaction between these two factors was observed (p < 0.0001). In muscle and liver, concentrations of Hg and Se were statistically higher in ruffe than in sichel and European perch. In gills, statistically highest concentrations of Mn, Sr, and Zn were found in sichel, and of Fe in European perch. In gonads, statistically highest concentrations of As were detected in sichel, of Zn in ruffe, and of Mn and Mo in European perch. The highest number of coefficients of partial correlations between fish weight and element levels was found in sichel (11 in total). Of all analyzed elements, Al and B had the highest number of partial correlations in tissues. The levels of Hg exceeded the maximum acceptable concentration (0.5 mg kg−1) in all muscle samples, which can pose a risk for human consumption. Different diet preferences of the investigated fish species resulted in a different accumulation of elements in tissues, and ruffe (as a species that consume mainly benthic macroinvertebrates) accumulated the highest level of Hg, which makes it suitable for monitoring of this element in water bodies.

Coralline algae and arsenic fixation in near shore sediments

Brazilian tropical beaches are enriched with arsenic (As) for hundreds of kilometres. The high levels of As in sediments, exceeding the legislative environmental thresholds, correlate by the presence of detritus material of geniculate calcareous algae involved in diagenetic processes in the coastal zone. Due to the porous structure of calcareous algae, the precipitation of iron hydroxides and subsequent absorption of arsenic occur not only on the surface but also in the inner parts of algal particles. The subsequent diagenetic filling of the cell lumen with calcium and magnesium carbonate preserves As inside the particles. This preservation contributes to the conservative behaviour of As in the changing geochemical conditions in sediments, and greatly reduces the efficiency of surf abrasion in the purification of beach sand from the high concentrations of As. The type of As enrichment in beach sands may exist in other regions of the world in addition to Brazil.

Effect of arsenic on δ-aminolevulinic acid formation in greening maize leaf segments

Supply of 0.5 mM Na2AsO4 significantly decreased the δ-amino levulinic acid (ALA) content and total chlorophylls in greening maize leaf segments with the effect being more substantial for the later. Inclusion of precursors of chlorophyll also affected the ALA content. Thus, % decrease by arsenic (As) was significantly reduced in the presence of glutamine and MgCl2, but was increased by glycine and succinate. ALA formation and chlorophyll content were significantly decreased by 0.5 mM Na2AsO4 during levulinic acid treatment in light as well as dark with more severe effect in light. Difference in ALA accumulation in light and dark (L–D) was also substantially decreased by higher concentrations of As. Inclusion of succinate and MgCl2, respectively, increased and decreased the % inhibition of ALA formation in light. In dark the addition of 2-oxoglutaric acid (2-OG), succinate and glycine caused an increase in % inhibition of ALA formation, while glutamate caused a decrease in inhibition. Inclusion of adenosine tri phosphate (ATP) increased the ALA formation in light in presence of As only, while pyridoxal phosphate (PLP) and MgCl2 enhanced it under both conditions. The results demonstrate more prominent decrease in total chlorophylls than ALA content and/or formation in the presence of As, indicating the involvement of other steps of chlorophyll biosynthesis in addition to ALA synthesis. Substantial decrease under dark at higher concentrations of As and protective effect of cofactors, such as, MgCl2, PLP and ATP in ALA formation in light suggests that chloroplastic ALA synthesizing activity is more sensitive to the presence of As.

Soft tissue measurement of arsenic and selenium in an animal model using portable X-ray fluorescence

Abstract The ingestion of trace amounts of arsenic (As) through drinking water is a relatively common pathway of exposure with potentially serious long-term health effects. Studies involving animal models have indicated that selenium (Se) may bind with As inside the body and facilitate excretion. A portable X-ray fluorescence (XRF) technique was previously developed to allow in vivo measurement of As and Se in human tissue. In the current paper, this portable XRF approach was tested for the first time using animal tissue. Seven female Lakeview Golden/LVG Syrian hamsters were dosed under either control, As-only, Se-only, or As and Se conditions. Minimum XRF detection limits in soft tissue of 1.00±0.05 ppm for As and 0.83±0.02 ppm for Se were determined from phantom calibration trials. For dosed hamsters, consistently higher concentrations of As and Se were found in the liver and gall bladder, with elevated levels also observed in the intestines. Concentrations ranged up to 26.4±1.4 ppm for As and 11.8±0.8 ppm for Se. The stomach and heart exhibited more moderate concentrations, while the brain, lung, and muscle demonstrated lower levels. For a given organ, As concentrations generally exceeded Se concentrations. A ratio of approximately 2.5:1 was observed for concentrations of As:Se when considering the same or similar tissue sites in dosed hamsters. Implications for potential in vivo human applications of the technique are briefly considered.

Distribution and age-related bioaccumulation of lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) in tissues of common carp (Cyprinus carpio) and European catfish (Sylurus glanis) from the Buško Blato reservoir (Bosnia and Herzegovina)

The purpose of this study was to quantify the bioaccumulation of Pb, Hg, Cd, and As in tissues of carp (Cyprinus carpio) and catfish (Silurus glanis) from Buško Blato in Bosnia and Herzegovina. Arsenic concentrations were below the Maximal Admissible Concentration (MAC) for Croatia and other countries. Mercury concentrations were below 1mgkg−1, but in most muscle samples of both species and all catfish liver samples, the values were higher than 0.5mgkg−1 (higher than the MAC for many countries including Croatia). Lead concentrations were higher than 1mgkg−1 (the MAC for Croatia) in most muscle samples; all kidney and most catfish liver samples also exceeded 1mgkg−1. Cadmium concentrations in all tissues, other than the gonads, were higher than 0.1mgkg−1 (MAC for Croatia), with the highest concentrations found in the kidneys. The only gender difference was found in carp, where a 68.4% higher concentration of As was found in the fry compared to the milt (P<0.05). Concentrations of all of the elements were higher in catfish compared to carp for most tissues. Significant correlations were found between all of the elements in the muscles and the liver of carp. In catfish, the muscles were the only tissue in which multiple correlations were found. Linear positive correlations with age and body mass were demonstrated for the concentrations of all heavy metals for all tissues except the gonads in both fish species. We concluded that significant heavy metal accumulation in carp and a catfish tissues correlates with age and body mass; bioaccumulation is species- and tissue-specific and is different for each element.

Assessment of heavy metal contamination in water and sediments of Trepça and Sitnica rivers, Kosovo, using pollution indicators and multivariate cluster analysis.

The concentrations of As, Cd, Cr, Co, Cu, Ni, Pb, and Zn in water and sediment samples from Trepça and Sitnica rivers were determined to assess the level of contamination. Six water and sediment samples were collected during the period from April to July 2014. Most of the water samples was found within the European and Kosovo permissible limits. The highest concentration of As, Cd, Pb, and Zn originates primarily from anthropogenic sources such discharge of industrial water from mining flotation and from the mine waste eroded from the river banks. Sediment contamination assessment was carried out using the pollution indicators such as contamination factor (CF), degree of contamination (Cd), modified degree of contamination (mCd), pollution load index (PLI), and geo-accumulation index (Igeo). The CF values for the investigated metals indicated a high contaminated nature of sediments, while the Cd values indicated a very high contamination degree of sediments. The mCd values indicate a high degree of contamination of Sitnica river sediment to ultrahigh degree of contamination of Trepça river sediment. The PLI values ranged from 1.89 to 14.1 which indicate that the heavy metal concentration levels in all investigated sites exceeded the background values and sediment quality guidelines. The average values of Igeo revealed the following ranking of intensity of heavy metal contamination of the Trepça and Sitnica river sediments: Cd > As > Pb > Zn > Cu > Co > Cr > Ni. Cluster analysis suggests that As, Cd, Cr, Co, Cu, Ni, Pb, and Zn are derived from anthropogenic sources, particularly discharges from mining flotation and erosion form waste from a zinc mine plant. In order to protect the sediments from further contamination, the designing of a monitoring network and reducing the anthropogenic discharges are suggested.

Chemical composition of bottom sediments within black hills region reservoirs of South Dakota and Wyoming

The objectives of this study were to determine the effect of heavy metals transported from mining areas due to historical mining activities within the Black Hills region of South Dakota and Wyoming US, and to evaluate the presence of major and trace elements resulting from influence of provenance, weathering, erosion, and sediment sorting within reservoir sediments. Soil core samples were collected from both inflow and outflow of the reservoirs. X-ray florescence analyses were performed to determine the presence of major and the trace elements concentration. Pactola and Sheridan Lakes had the highest concentration of As, Fe, Mn, and Rb/Sr ratios, while the Belle Fourche Reservoir had the highest U concentration. Spatial and temporal patterns of Rb/Sr ratio of the reservoir sediments were used to determine the weathering intensity of the catchment areas. With the exception of Angostura and LAK reservoirs, all Black Hills reservoirs were dominated by physical weathering processes within their respected watersheds. Immobile high field strength elements from within the reservoir sediments were higher compared to upper continental crust (UCC) concentrations, and further suggest the dominance of physical weathering processes for all reservoirs except LAK. Spider diagrams normalized to UCC concentrations indicate that Black Hills regional reservoirs were elevated in Zr, Hf, and U, further supporting the dominance of physical or mechanical weathering influences from their watersheds. Watersheds dominated by physical weathering processes are commonly subjected to high erosion, anthropogenic activities, and/or high precipitation processes.

The Multiple Roles of Sulfate-Reducing Bacteria and Fe-Ti Oxides in the Genesis of the Bayinwula Roll Front-Type Uranium Deposit, Erlian Basin, NE China

The Bayinwula roll front-type uranium deposit is hosted in sandstones of the Early Cretaceous Saihan Formation deposited during the postrift stage of the Erlian basin, in northeast China. The present study aims to characterize: (1) the roles of sulfate-reducing bacteria and (2) the roles of Fe-Ti oxides in the genesis of the Bayinwula deposit. Drill cores of the host sandstone have been investigated with emphasis on petrographic observations, whole-rock geochemistry, and geochemical and/or mineralogical study of Fe-Ti oxides, iron disulfide, uranium minerals (EMP, LA-ICPMS), and organic matter (rock-eval pyrolysis). The δ 34 S value has been measured in situ by SIMS on the different generations of iron disulfide. Within regional sandstones, preore uranium enrichment (U mean = 30.4 ppm in whole rock) was identified on altered Fe-Ti oxides (38.5% of the whole-rock U content) and constitutes a major source of uranium for the mineralization. Petrographic observations and rock-eval data indicate that organic matter occurring in the host sandstone is mainly inherited from land plants and corresponds to type III or type IV kerogens. Organic matter fragments disseminated in sandstones may also contain significant preore uranium concentration. Framboidal and collomorph ore-stage iron disulfides have moderate to high concentrations of As, Ni, and Co and have a light sulfur isotope signature characterized by δ 34 S values from −30.5 to −7.5‰, suggesting that sulfur originated from bacterial sulfate reduction, which was mainly responsible for (1) the liberation of U from Fe-Ti oxides and organic matter, (2) the generation of ore-stage iron disulfides, and (3) the production of a secondary H 2 S-rich reducing barrier involved in the reduction of U(VI) and the precipitation of U(IV). Uranyl and sulfate ions were transported through the host sandstone by low-temperature oxygenated groundwater and U(IV) was precipitated at the redox front as P-rich coffinite and ningyoite, dominantly as replacement of ore-stage iron disulfides which have partly to totally replaced organic matter and Fe-Ti oxides. Therefore, the combined mineralogical, geochemical, and isotopic characteristics of the Bayinwula roll-front uranium deposit support the theory that biogenic processes have widely contributed to the genesis of the uranium mineralization.

Geochemical background of potentially toxic trace elements in soils of the historic copper mining area: a case study from Miedzianka Mt., Holy Cross Mountains, south-central Poland

The aim of this study was to evaluate the geochemical background and spatial distribution patterns of selected trace elements (As, Cd, Cr, Cu, Mn, Ni, Pb, U and Zn) in 62 surface soil samples collected in the historic Cu mining area (Miedzianka Mt., Holy Cross Mountains, south-central Poland). In the study area the mining activity dates back to the fourteenth century. After the shutdown of mining operations in 1953, the soil was not remediated and neither its mineralogy nor chemistry was examined. The examined soils showed a high variability in the element concentrations. The threshold values defined as the upper limits of geochemical background range (mg kg−1 in parentheses) were Cr (63), Mn (2156), Ni (39), Cu (52), Zn (175), As (36), Cd (2), Pb (73) and U (1.9). A high percentage of the samples exhibited trace element concentrations above the upper limit of the geochemical background range. The threshold values were evaluated in this study with application of the iterative 2σ-technique. All of these values exceeded the standards recommended for soils in protected areas of Poland. The sampling points with anomalous concentrations of potentially toxic trace elements were located mostly in southern and western parts of the study area close to the sites of former mining activities. Very high concentrations of As, Cr and Ni at several sites may adversely influence the environment. High positive correlations between all the determined elements may be indicative of a common geogenic source of these elements and their geochemical affinity.

Cuttlefish capsule: An effective shield against contaminants in the wild

Increasing anthropogenic pressures in estuaries are responsible for the rise of contaminants in several compartments of these ecosystems. Species that benefit from the nursery services provided by estuaries are exposed to such contaminants (e.g. metals and metalloids). It is therefore relevant to understand if marine invertebrates that use these areas as spawning grounds accumulate contaminants in their tissues throughout embryogenesis. This study aimed to quantify As, Co, Cr, Cu, Mn, Ni, Se, Pb, V and Zn concentrations in both capsule and embryos of the common cuttlefish (Sepia officinalis) in Sado Estuary (Portugal). Moreover, embryos at their initial, intermediate and final stage of development were collected in sites subjected to different anthropogenic pressures. In general, the capsule accumulated higher element concentration throughout embryogenesis which indicates that the capsule acts as an effective barrier against contaminants uptake by the embryo. Although the capsule becomes thinner throughout embryogenesis, embryo’s protection does not seem to be compromised at later development stages. Additionally, the higher concentrations of As, Cu, Se and Zn in the embryo in comparison to the capsule suggests important biological roles during the embryogenesis of this cephalopod mollusc.

Oxidative injury and antioxidant enzymes regulation in arsenic-exposed seedlings of four Brassica napus L. cultivars.

Environmental contamination due to arsenic (As) has become a major risk throughout the world; this affects plant growth and productivity. Its accumulation in food chain may pose a severe threat to organisms. The present study was carried out to observe the toxic effects of As (0, 50, 100, and 200 μM) on physiological and biochemical changes in four Brassica napus cultivars (ZS 758, Zheda 619, ZY 50, and Zheda 622). Results showed that As toxicity provoked a significant inhibition in growth parameters of B. napus cultivars and this reduction was more obvious in cultivar Zheda 622. The highest concentration of MDA, H2O2, and O2 (-) contents in both leaf and root tissues were observed at 200 μM As level, and a gradual decrease was observed at lower concentrations. Increasing As concentration gradually decreased chlorophyll and carotenoids contents. Activity of antioxidant enzymes such as SOD, CAT, APX, GR, and GSH was positively correlated with As treatments in all cultivars. The microscopic study of leaves and roots at 200 μM As level showed the disorganization in cell organelles. Disturbance in the morphology of chloroplast, broken cell wall, increase in size, and number of starch grains and immature nucleus were found in leaf ultrastructures under higher concentration of As. Moreover, damaged nucleus, diffused cell wall, enlarged vacuoles, and a number of mitochondria were observed in root tip cells at 200 μM As level. These results suggest that B. napus cultivars have efficient mechanism to tolerate As toxicity, as evidenced by an increased level of antioxidant enzymes.

Trace elements in the Fontinalis antipyretica from rivers receiving sewage of lignite and glass sand mining industry.

Intensive lignite and glass sand mining and industrial processing release waste which may contain elements hazardous to the aquatic ecosystem and constitute a potential risk to human health. Therefore, their levels must be carefully controlled. As a result, we examined the effects of sewage on the aquatic Fontinalis antipyretica moss in the Nysa Łużycka (lignite industry) and the Kwisa Rivers (glass sand industry). The Nysa Łużycka and the Kwisa Rivers appeared to be heavily polluted with As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn, which were reflected in the extremely high concentration of these elements in F. antipyretica along the studied watercourses. In the Nysa Łużycka, trace element composition in the moss species is affected by lignite industry with accumulation in its tissues of the highest concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn, while samples from the Kwisa sites influenced by glass sand industry revealed the highest concentrations of As, V and Fe. The principal component and classification analysis classifies the concentration of elements in the aquatic F. antipyretica moss, thus enabling the differentiation of sources of water pollution in areas affected by mining industry.

Geochemical Trends of Trace Elements Concentration in Saline Lakes of Central Asia

The investigated Mongolian lakes are marked by a large range of trace element concentrations even in very small geographical areas. This work includes the data on major and trace element concentrations along of a series of samples collected in 2009 and 2012. Three geochemical types of lakes have been distinguished within the study area: (1) alkaline soda lakes, (2) chloride lakes with pH &lt; 9.0 and Na-Cl-dominated composition, and (3) sulfate ones with pH &lt; 8. The soda lakes show high concentrations of As, U, F and relatively low salinity. The chloride lakes have higher salinities and one of them was the most saline of all the lakes (Davsan Nuur). These lakes have higher concentrations of Li (up to 82.1 mg/L), Rb (up to 1350 mg/L), Br and Sr. Sulfate rich lakes are far less common in the area. Characteristic trace elements are Mo, Al and Sr. Thermodynamic modeling at 25°C and 1 bar total pressure was performed with the “HCh” code. We considered mineral and solution equilibria in soda lake waters and calculated the main uranium and arsenic species in solutions and bottom sediments of Shaazgay-Nuur lake to offer a possible way of As removal as an undesirable impurity in commercial products.

Characterization of heavy metal and antibiotic-resistant bacteria isolated from polluted localities in Egypt

Objective The aim of this study was to isolate and identify heavy metal-resistant and antibiotics-resistant bacteria from contaminated samples (wastewater and soil) collected from different industrial areas in Egypt and determine their role in heavy metal removing. Materials and methods Samples were collected from Helwan and 10th of Ramadan city areas and enriched in culture broth containing 200, 100, and 10 ppm of arsenic (As), lead (Pb), and cadmium (Cd) as AsHNa 2 O 4·H 2 O, Pb(NO 3 ) 2 , and CdSO 4 , respectively. The highly resistant isolate (ST6) was selected and identified biochemically and also subjected to 16S rDNA sequencing. The growth parameters were optimized and the maximum tolerable concentration of the respective metals as well as the antibiotic resistance was determined. Result and conclusion After enrichment culture we isolated and purified 20 bacterial isolates resistant to the respective heavy metals As, Pb, and Cd. The morphological, biochemical, and phylogenetical characteristics of the most resistant bacterial isolates (ST6) were studied. The results showed that this isolate belongs to the species Pseudomonas stutzeri. The optimum temperature was 35°C, whereas the optimum pH was in the range of 6-7. Maximum tolerable concentration values for As, Pb, and Cd were 3500, 1750, and 50 ppm, respectively. Also, the isolate ST6 showed resistance against different antibiotics. The metal removal ability was 42.5, 57.1, and 52.9% of As, Pb, and Cd, respectively. It was concluded that the ST6 isolate was resistant and removed high concentrations of As, Pb, and Cd. Hence, this isolate may play a role in bioremediation processes of heavy metal in polluted areas.

Concentration of Particulate Platinum-Group Minerals during Magma Emplacement; a Case Study from the Merensky Reef, Bushveld Complex

AbstractThe petrology, mineralogy and geochemistry of a section of the Merensky Reef at Bafokeng Rasimone Platinum Mine (BRPM) are described. A model for the formation of platinum-group minerals (PGM), sulphide and chromitite is proposed that explains the stratigraphic relationships observed in the Merensky Reef, both at BRPM and at other locations in the Bushveld Complex. To achieve this it is necessary to understand platinum-group element (PGE) behaviour in naturally occurring mafic systems and for this reason comparisons are drawn from core TN207 through the Platreef at Tweefontein. The common link between the Platreef and Merensky Reef is the presence of unusually high concentrations of As, Sb, Bi and Te that promote the crystallisation of semi-metal bearing PGM from sulphide liquids. Under conditions of increasing semi-metal contamination, Pt is the first PGE to be extracted from a sulphide liquid followed by Rh, Ru, Os and Ir. While some Pd is released to form Pd-PGM much of it remains within the Ni-rich sulphide phase that crystallizes to form pentlandite. A critical aspect is the timing of their introduction into the magmatic system. For the Merensky magmas, contamination occurred predominantly within a staging chamber owing to wall-rock interaction with Transvaal sediments. This led to the formation of sulphide liquids that captured PGE and, ultimately, the crystallization of Pt- and Ru-PGM. The extreme enrichment in PGE and the high Pt/Pd ratios in the Merensky chromitites are attributed to density-driven concentration of PGM transported by magmas displaced from a staging chamber. Emplacement of these magmas into the Bushveld Complex resulted in thermo-mechanical erosion of the floor and deposition of chromites + sulphides + PGM. In places, these assemblages collected in sedimentary-like scour channels. In the Platreef, contamination occurred largely after magma emplacement owing to interaction with the local Transvaal sediments. As a result, mechanical separation of PGM did not occur and most PGM remain spatially associated with their original sulphide hosts.The Merensky Reef is a prime example of highly efficient PGE concentration resulting from mechanical processes, whereas the Platreef is a prime example of highly efficient PGE removal from sulphide liquids in response to extreme contamination by semi-metals.

Comparison of Eleven Heavy Metals in Moringa Oleifera Lam. Products.

Eleven heavy metals in various products of Moringa oleifera were analyzed to determine eleven heavy metals (Al, As, Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni, and Zn) using Inductively Coupled Plasma-Mass Spectrometry. The products of M. oleifera were purchased in Nakhon Pathom, Thailand. All products were digested with nitric acid solution before determining the concentrations of heavy metals. The recoveries of all heavy metals were found to be in the range of 99.89-103.05%. Several criteria such as linearity, limits of detection, limits of quantification, specificity, precision under repeatability conditions and intermediate precision reproducibility were evaluated. Results indicate that this method could be used in the laboratory for determination of eleven heavy metals in M. oleifera products with acceptable analytical performance. The results of analysis showed that the highest concentrations of As, Cr, Hg, and Mn were found in tea leaves while the highest concentrations of Al, Cd, Cu, Fe, Ni, Pb, and Zn were found in leaf capsules. Continuous monitoring of heavy metals in M. oleifera products is crucial for consumer health.

Comparison of the chemical composition of British and Continental European bottled waters by multivariate analysis

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30μgL−1) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455μgL−1). Italian waters showed the highest concentrations of Sr (3000–8000μgL−1) and U (8–13μgL−1), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4μgL−1). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.