Tin Mining Area Research Articles

Quantitative Study of Elements Migration during the Wall Rock Alteration Process for Gejiu Copper-Polymetallic Deposit inside Rock

With continuous consumption of proven resources, people have to turn to new resources or find new ways for prospecting. As to Yunnan Gejiu Tin and copper polymetallic deposit, deep ore prospecting may be the solution. The newly discovered copper-polymetallic deposit inside the rock of Tangzi’ao depression zone, which located in western part of Yunnan Gejiu east tin mine area, is a new type of deposit in deep ore prospecting. This kind of deposit produced in the alkali-rich, oxidizing environment, potash feldspathization is an important sign of prospecting, and a variety of metallic elements can be comprehensive utilization. It is special that potash feldspathization zone and epidotization zone alternating with each other; the phenomenon may caused by multi-period of hydrothermal fluids. By quantitative calculating the results of altered rocks and original rock samples, the author find out the migration laws of the constant elements and the main ore-forming elements and their associated elements, which provide a basis for prospecting in the future.

Phylogenetic and phenotypic analyses of arsenic-reducing bacteria isolated from an old tin mine area in Thailand

An agar plate screening assay was used to determine whether 100 arsenic-resistant bacterial isolates, previously obtained from arsenic-contaminated soils, had the ability to transform arsenite and arsenate. Ninety-five percent of the isolates were capable of reducing arsenate on agar plates. The isolates also grew in the presence of high concentrations of arsenite, but none of the bacterial isolates oxidized arsenite to arsenate under the growth conditions tested. About 14 % (13 of 95) of the tested isolates transformed high levels of arsenate (33-70 μM) when tested using the molybdenum blue method. Partial sequence analysis of 16S rDNA genes indicated that the isolates belonged to two broad taxonomic groups: Firmicutes and Proteobacteria. Ten isolates were assigned to four species in the genus Bacillus, and three isolates belonged to two species in the genera Enterobacter and Ochrobactrum. Taken together these results indicate that phylogenetically diverse bacteria isolated from arsenic-contaminated soils in an old tin mine area in Thailand have the ability to transform arsenate to arsenite.

Evolution of mineralizing fluids of cassiterite–wolframite and fluorite deposits from Mueilha tin mine area, Eastern Desert of Egypt, evidence from fluid inclusion

Sn–W deposit of the Mueilha mine is one of many other Sn–W deposits in the Eastern desert of Egypt that associated with albite granite. Two forms of Sn–W mineralizations are known at the Mueilha Sn-mine area, namely fissure filling quartz veins and greisen. Cassiterite and/or wolframite, sheelite, and beryl are the main ore minerals in the greisen and quartz veins. Subordinate chalcopyrite and supergene malachite and limonite are also observed in the mineralized veins. To constrain the P–T conditions of the Sn–W mineralizations, fluid inclusions trapped in quartz and cassiterite, have been investigated. The following primary fluid inclusion types are observed: CO2-rich, two-phase (L + V) aqueous, and immiscible three-phase (H2O–CO2) inclusions. Low temperature and low salinity secondary inclusions were also detected in the studied samples. Microthermometric results revealed that Sn–W deposition seem to have taken place due to immiscibility at temperature between 260°C and 340°C, and estimated pressure between 1.2 to 2.2 kb. Microthermometric results of fluid inclusions in fluorite from fluorite veins illustrated that fluorite seems to be deposited due to mixing of two fluids at minimum temperature 140°C and 180°C, and estimated minimum pressure at 800 bars.

Role of Methylmercury Exposure (from Fish Consumption) on Growth and Neurodevelopment of Children Under 5 Years of Age Living in a Transitioning (Tin-Mining) Area of the Western Amazon, Brazil

Human occupation of the Amazon region has recently increased, bringing deforestation for agriculture and open-cast mining, activities that cause environmental degradation and pollution. Families of new settlers in mining areas might have a diet less dependent on abundant fish and their children might also be impacted by exposures to mining environments. Therefore, there is compounded interest in assessing young children's nutritional status and neurobehavioral development with regard to family fish consumption. Anthropometric (z-scores, WHO standards) and neurologic [Gesell developmental scores (GDS)] development in 688 preschool children (1-59 months of age) was studied. Overall, the prevalence of malnutrition [i.e., moderate stunting (≤2 H/A-Z), underweight (≤2 W/A-Z), and wasting (≤2 W/H-Z) were respectively 0.3% (n = 2), 1.6% (n = 11), and 2.5% (n = 17). Children's mean hair Hg (HHg) concentration was 2.56 μg/g (SD = 1.67); only 14% of children had HHg concentrations lower than 1 μg/g and 1.7% had ≥5 μg/g. The biomarker of fish consumption was weakly but positively correlated with GDS (Spearman r = 0.080; p = 0.035). In the bivariate model, attained W/H-Z scores were not significantly correlated with GDS. A moderate level of GDS deficits (70-84%) was seen in 20% of children. There was significant correlation between family fish consumption and children's hair Hg (HHg) (Spearman r = 0.1756; p < 0.0001) but no significant correlation between children's HHg and W/H-Z scores. However, the multivariate model showed that breastfeeding, a fish consumption biomarker (HHg), maternal education, and child's age were statistically significant associated with specific domains (language and personal-social) of the Gesell scale. In this mining environment, family fish-eating did not affect children's linear growth, but it showed a positive influence (along with maternal variables) on neurodevelopment. Health hazards attendant on a high prevalence of moderate neurodevelopment delays coexisting with exposure to multiple neurotoxic substances merits further investigation in poor environmental settings of tin-mining areas.

Diversity and community structure of culturable arsenic-resistant bacteria across a soil arsenic gradient at an abandoned tungsten–tin mining area

We studied the bacterial diversity at a single location (the Terrubias mine; Salamanca province, Spain) with a gradient of soil As contamination to test if increasing levels of As would (1) change the preponderant groups of arsenic-resistant bacteria and (2) increase the tolerance thresholds to arsenite [As(III)] and arsenate [As(V)] of such bacteria. We studied the genetic and taxonomic diversity of culturable arsenic-resistant bacteria by PCR fingerprinting techniques and 16S rRNA gene sequencing. Then, the tolerance thresholds to As(III) and As(V) were determined for representative strains and mathematically analyzed to determine relationships between tolerances to As(III) and As(V), as well as these tolerances with the soil contamination level. The diversity of the bacterial community was, as expected, inversely related to the soil As content. The overall preponderant arsenic-resistant bacteria were Firmicutes (mainly Bacillus spp.) followed by γ-Proteobacteria (mainly Pseudomonas spp.), with increasing relative frequencies of the former as the soil arsenic concentration increased. Moreover, a strain of the species Rahnella aquatilis (γ-Proteobacteria class) exhibited strong endurance to arsenic, being described for the first time in literature such a phenotype within this bacterial species. Tolerances of the isolates to As(III) and As(V) were correlated but not with their origin (soil contamination level). Most of the strains (64%) showed relatively low tolerances to As(III) and As(V), but the second most numerous group of isolates (19%) showed increased tolerance to As(III) rather than to As(V), even though the As(V) anion is the prevalent arsenic species in soil solution at this location. To our knowledge, this is the first study to report a shift towards preponderance of Gram-positive bacteria (Firmicutes) related to high concentrations of soil arsenic. It was also shown that, under aerobic conditions, strains with relatively enhanced tolerance to As(III) predominated over the most As(V)-tolerant ones.

The Malayan Emergency: General Templer and the Kinta Valley Home Guard, 1952-1954

This is an account of the Kinta Valley Home Guard (KVHG), which played a vital role in protecting Chinese tin mines in the Kinta Valley in Perak from the attacks of the communist insurgents during the first Malayan Emergency. The Kinta Valley, covering some 1035 square kilometres, was one of the richest tin-mining areas in Malaya, and accounted for the major part of Malaya's tin exports to the USA, the revenue from which was one of the most important sources of US dollars in the British colonial empire. The KVHG, which was established by the Perak Chinese Tin Mining Association, was unique in that it had the personal backing and support of General Sir Gerald Templer, High Commissioner and Director of Operations, Malaya, who paid close attention to its development. General Templer's decision to support the KVHG was controversial at the time, and the KVHG was often described as a private 'Chinese Army', especially as many of its members were known to have Kuomintang connections. Colonel H. S. Lee (subsequently Tun Colonel Sir Henry Hau Sik Lee) was closely associated with the KVHG, and this paper makes use of, for the first time, his private papers that have been deposited with the ISEAS (Institute of SE Asian Studies) Library, Singapore.

A complimentary tool in the determination of activity concentrations of naturally occurring radionuclides

The determination of activity concentrations of radionuclides requires a reliable gamma spectrometry system, which also depends on the compulsory attainment of secular equilibrium amongst the progenies of the radionuclide of interest. This is often difficult to attain and hence a helium particle induced x-ray emission technique, not requiring the compulsory attainment of secular equilibrium, was used to determine the actual concentrations of the elemental content of tailings from the high background radiation tin mining area, Jos, Nigeria. The activity concentrations of the radionuclides of 40K, 232Th and 238U were also calculated based on their elemental analyses, providing reliable information about the heads of uranium ( 238U) and thorium ( 232Th) series on the study area.

Structure and Diversity of Arsenic Resistant Bacteria in an Old Tin Mine Area of Thailand

The microbial community structure in Thailand soils contaminated with low and high levels of arsenic was determined by denaturing gradient gel electrophoresis (DGGE). Band pattern analysis indicated that the bacterial community was not significantly different in the two soils. Phylogenetic analysis obtained by excising and sequencing six bands indicated that the soils were dominated by Arthobacter koreensis and proteobacteria. Two hundred and sixty-two bacterial isolates were obtained from arsenic contaminated soils. The majority of the As resistant isolates were gram-negative bacteria. MIC studies indicated that all of the tested bacteria had greater resistance to arsenate than arsenite. Some strains were capable of growing in medium containing up to 1,500 mg/l arsenite and arsenate. Correlations analysis of resistance patterns of arsenite resistance indicated that the isolated bacteria could be categorized into 13 groups, with a maximum similarity value of 100%. All strains were also evaluated for resistance to eight antibiotics. The antibiotic resistance patterns divided the strains into 100 unique groups, indicating that the strains were very diverse. Isolates from each antibiotic resistance group were characterized in more detail by using the repetitive extragenic palindromic-PCR (rep-PCR) DNA fingerprinting technique with ERIC primers. PCR products were analyzed by agarose gel electrophoresis. The genetic relatedness of 100 bacterial fingerprints, determined by using Pearson product moment similarity coefficient, showed that the isolates could be divided into four clusters, with similarity values ranging from 5-99%. While many isolates were genetically diverse, others were clonal in nature Additionally, the arsenic-resistant isolates were examined for the presence of arsenic resistance (ars) genes by using PCR, and 30% of the isolates were found to carry an arsenate reductase encoded by the arsC gene.

Uranium and thorium in soils, mineral sands, water and food samples in a tin mining area in Nigeria with elevated activity

The activity concentrations of uranium and thorium have been determined in soils and mineral sands from the Nigerian tin mining area of Bisichi, located in the Jos Plateau, and from two control areas in Nigeria (Jos City and Akure) using high-purity germanium detectors (HPGe). High resolution sector field inductively coupled plasma mass spectroscopy (HR-SF-ICP-MS) was used to determine uranium and thorium in liquids and foodstuffs consumed locally in the mining area. The activities of uranium and thorium measured in the soils and mineral sands from Bisichi ranged from 8.7 kBq kg −1 to 51 kBq kg −1 for 238U and from 16.8 kBq kg −1 to 98 kBq kg −1 for 232Th, respectively. These values were significantly higher than those in the control areas of Jos City and Akure and than the reference values reported in the literature. They even exceeded the concentrations reported for areas of high natural radioactive background. Radionuclide concentrations in samples of the local foodstuffs and in water samples collected in Bisichi were found to be higher than UNSCEAR reference values. The results reveal the pollution potential of the mining activities on the surrounding areas.

Economic Mineral Potentials Of Tailing Dumps From Alluvial Mining In Parts Of Jos Plateau, Northcentral Nigeria

Several tonnes of mine tailing dumps abound in the alluvial tin mining areas of the Jos Plateau. These tailings are considered low in contents of cassiterite, columbite, tantalite, zircon and other minerals normally won from tin mining. Four of these dumps in four different mines located in Barkin Ladi (BL), Gurum (GM), Sabon Gida Dan Yaya (SGDY) and Sabon Gida Kanar (SGK) have been studied to assess their economic potentials. Samples were collected and analysed using AAS for tin, niobium, tantalum and iron; colorimetry for titanium and gravimetry for zirconium. The results of the initial geochemical analyses showed the contents of tin ( Keywords :Jos Plateau, Alluvial, Tin mines, Tailings, Recovery. Global Journal of Geological Sciences Vol. 6 (1) 2008: pp. 41-16

Arsenic and Heavy Metal Concentrations in Agricultural Soils Around Tin and Tungsten Mines in the Dai Tu district, N. Vietnam

This study assessed the arsenic and heavy metal contaminations of agricultural soils around the tin and tungsten mining areas in Dai Tu district in northern Vietnam. Among the examined elements, high total contents of As and Cu were found in the agricultural fields at both tin and tungsten mining sites. Although the major part of the accumulated As and Cu were bound by various soil constituents such as Fe and Mn oxides, organic matter, and clay minerals, increases in water soluble As and Cu were observed, especially for the paddy fields. The results suggest that, in the studied area, As and Cu dispersion from their pollution sources into farmlands is mainly via fluvial transportation of mine waste through streams that cross the paddy fields around the tin mining area, and soil erosion at the tea fields located at lower positions of the slope in the tungsten mining area.

Exposure to high background radiation level in the tin mining area of Jos Plateau,Nigeria

The present work deals with the radioactivity of samples of tin tailings collected from amining site in Jos, Nigeria. The activity concentrations of the samples were measured usinga gamma-ray spectrometer with a hyper-pure germanium detector. In situ dose rates atthe site were also measured using a precalibrated survey meter. Potassium-40was not detected in any of the studied samples. The activity concentrations of238U and232Th rangedfrom 17.1 × 102 to 16.6 × 103 Bq kg−1 andfrom 52.9 × 102 to47.5 × 103 Bq kg−1, with meanvalues of 72.2 × 102 and 16.8 × 103 Bq kg−1, respectively. The absorbed dose rates were between 4.0 and36.3 µGy h−1, with amean value of 13.5 µGy h−1, which is much higher than the world average of0.06 µGy h−1 for soil. The calculated effective dose rates varied between 2.8 and25.4 µSv h−1, with amean value of 9.4 µSv h−1, whereas the effective dose rates obtained for the in situ measurement varied between 6.0 and28.0 µSv h−1. The annual gonadal dose equivalent was calculated as 92.4 mSv. This is muchhigher than the world average dose equivalent rate to individuals from soil(0.30 mSv y−1).

Estimation of annual effective dose due to natural radioactive elements in ingestion of foodstuffs in tin mining area of Jos-Plateau, Nigeria

Soils and food crops from a former tin mining location in a high background radiation area on the Jos-Plateau, Nigeria were collected and analyzed by gamma spectrometry to measure their contents of 40K, 238U and 232Th. As well as collecting samples, in situ dose rates on farms were measured using a precalibrated survey meter. Activity concentrations determined in food crops were compared with the local food derivatives or diets to investigate the possible removal or addition of radionuclides during food preparation by cooking or other means. Potassium-40 was found to contribute the highest activity in all the food products. The activity concentration of 40K, 238U and 232Th in local prepared diets ranged between 60 and 494 Bq kg −1, between BDL and 48 Bq kg −1 and between BDL and 17 Bq kg −1, respectively. The internal effective dose to individuals from the consumption of the food types was estimated on the basis of the measured radionuclide contents in the food crops. It ranged between 0.2 μSv y −1 (beans) and 2164 μSv y −1 (yam) while the annual external gamma effective dose in the farms due to soil radioactivity ranged between 228 μSv and 4065 μSv.

Determination of arsenic species in fish, crustacean and sediment samples from Thailand using high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS).

Suitable techniques have been developed for the extraction of arsenic species in a variety of biological and environmental samples from the Pak Pa-Nang Estuary and catchment, located in Southern Thailand, and for their determination using HPLC directly coupled with ICP-MS. The estuary catchment comprises a tin mining area and inhabitants of the region can suffer from various stages of arsenic poisoning. The important arsenic species, AsB, DMA, MMA, and inorganic arsenic (As III and V) have been determined in fish and crustacean samples to provide toxicological information on those fauna which contribute to the local diet. A Hamilton PRP-X100 anion-exchange HPLC system employing a step elution has been used successfully to achieve separation of the arsenic species. A nitric acid microwave digestion procedure, followed by carrier gas nitrogen addition- (N2)-ICP-MS analysis was used to measure total arsenic in sample digests and extracts. The arsenic speciation of the biological samples was preserved using a Trypsin enzymatic extraction procedure. Extraction efficiencies were high, with values of 82-102%(As) for fish and crustacean samples. Validation for these procedures was carried out using certified reference materials. Fish and crustacean samples from the Pak Pa-Nang Estuary showed a range for total arsenic concentration, up to 17 microg g(-1) dry mass. The major species of arsenic in all fauna samples taken was AsB, together with smaller quantities of DMA and, more importantly, inorganic As. For sediment samples, arsenic species were determined following phosphoric acid (1 M H3PO4) extraction in an open focused microwave system. A phosphate-based eluant, pH 6-7.5, with anion exchange HPLC coupled with ICP-MS was used for separation and detection of AsIII, AsV, MMA and DMA. The optimum conditions, identified using an estuarine sediment reference material (LGC), were achieved using 45 W power and a 20 minute heating period for extraction of 0.5 g sediment. The stability and recovery of arsenic species under the extraction conditions were also determined by a spiking procedure which included the estuarine sediment reference material. The results show good stability for all species after extraction with a variability of less than 10%. Total concentrations of arsenic in the sediments from the Pak Pa-Nang river catchment and the estuary covered the ranges 7-269 microg g(-1)and 4-20 [micro sign]g g(-1)(dry weight), respectively. AsV was the major species found in all the sediment samples with smaller quantities of AsIII. The presence of the more toxic inorganic forms of arsenic in both sediments and biota samples has implications for human health, particularly as they are readily 'available'.

A comparison of brachyuran crab community structure at four mangrove locations under different management systems along the Melaka Straits-Andaman Sea Coast of Malaysia and Thailand

Brachyuran crab community structure was compared between mangrove sites under different management systems from four locations along the Melaka Straits-Andaman Sea Coast. Klong Ngao, a mangrove estuary in Ranong Province of southern Thailand, lies within a Biosphere Reserve designated in 1997. Sites were positioned in plantations at a former charcoal concession forest, a disused tin mine, and an abandoned shrimp pond along this estuary. The Merbok estuary in Kedah, Malaysia, is partially managed: the mangroves are cut for charcoal and poles on a small scale and the forests are left to regenerate naturally. The Matang Mangrove Forest Reserve in Perak, Malaysia, is heavily exploited but well managed, forRhizophora wood to produce charcoal, and has been for 100 years. Sites were positioned in plantations of different ages. Kuala Selangor Nature Park, Selangor, Malaysia, was established as a nature reserve in 1987 and contains mature mangrove forest regenerating naturally from previous selective felling. At Klong Ngao and Matang, mature reserve forest sites were also studied for comparison with plantation sites. The sites included both upstream and downstream locations and were of similar area, minimizing effects from possible species-area relationships. Sites were chosen with similar environmental conditions and with a dominance ofRhizophora spp. At each site per location, the brachyuran crabs were sampled quantitatively in 100 m2 quadrats by three independent 15-min timed crab catches. The crab community recorded was analyzed by univariate and multivariate statistical techniques. Management history plays an important role in moderating the crab community structure. The crab community also changes with the age of the mangrove forest stand. Sesarmid crabs consistently dominated in mature forests, whereas young plantations were colonized mainly by ocypodid crabs. The findings show that heavily effected sites—e.g., disused tin mining areas, former concession forests, and abandoned shrimp ponds—can be rehabilitated by planting mangroves and that the crab community is a useful ecological indicator of habitat status.

Trace metal levels in soils and vegetation from some tin mining areas in Nigeria

Samples of soil and vegetation from some tin mining areas of Nigeria were analysed for lead, zinc, copper and cadmium content. The levels of Pb and Zn were found to be high in some samples. The mean levels of metal in the vegetation were: 86.6+ 36.0, 49.6+ 28.3, 12.6+4.8 and 1.4+0.8 µgg-1 dry weight for Pb, Zn, Cu and Cd respectively whilst those in the soil were 736+120, 690+ 216, 43+ 18 and 18+12 µgg-1 dry weight for Pb, Zn, Cu and Cd respectively. The variability of metal levels in the area indicates that in addition to mining, other anthropogenic sources of metal contribute significantly to metal levels in the area. The EDTA – extractable metal fractions suggest that trace metals are being mobilised in the soil and made available to crops. The metal levels in the vegetation samples were higher than those recorded for areas of low atmospheric metal pollution in Nigeria with no identifiable sources. Although, there have been no cases of recorded metal toxicity in the area, there is the need to regulate and control mining wastes in order to prevent the effects of metal pollution in the area. Key words: metals, environmental samples, mining areas. [Global Jnl Pure & Appl. Sci. Vol.9(3) 2003: 331-338]

GIS Application on Arsenic Contamination and Its Risk Assessment in Ronphibun, Nakhorn Si Thammarat, Thailand

This paper presents a case study of GIS application on arsenic contamination and its toxicological effects in a tin mining area of southern Thailand. A GIS database was constructed which depicted the arsenic distribution profiles in different environmental media, i.e. the shallow groundwater, deep groundwater and near-surface soil. Estimation from the GIS interpolation showed that 72.31% of the study area had arsenic level higher than 0.05mg/L (Thailand standard) in shallow groundwater, The contamination situation in deep groundwater was more severe than shallow groundwater. Six major contamination sources were identified through correlation analysis between arsenic level in soil/groundwater sample sites with the distance to mining and waste dumping sites. The correlation between arsenism patients' distribution with arsenic concentration and other geological features were analyzed, the results showed a significant difference between the groundwater arsenic concentration inside and outside the distribution zone of arsenism patients. With the help of GIS, arsenic hot spots in each media were displayed. Arsenic risk assessment was also conducted in four villages based on the arsenic exposure from drinking water, which found that village 12 had the highest risk due to arsenic consumption.

Fractionation of arsenic in soil by a continuous-flow sequential extraction method.

Batch sequential extraction techniques for fractionating metals or metalloids in soils are time consuming and subject to several potential errors. The development of a continuous-flow sequential extraction method for soil As is described and assessed, having the benefits of simplicity, rapidity, less risk of contamination, and less vulnerability to changes in extraction conditions compared with traditional batch methods. The validated method was used to fractionate soil As using water, NaHCO3, NaOH, and HCl, followed by digestion of the residue with HNO3 and HF acids. The extracts and digests were analyzed for As by graphite furnace atomic absorption spectrometry. Good recoveries of total soil As (97-115%) were obtained and fractionation data generally comparable with those obtained using conventional batch techniques. Soils from a tin-mining area in Thailand and soils from As-contaminated cattle (Bos taurus) dip sites in Australia were used to test the applicability of the method, and to demonstrate the usefulness of the extractogram obtained. The ability to produce detailed extractograms for As and other elements (Al, Fe, and Ca) enabled an examination of elemental associations in individual fractions. With the exception of As extracted with HCl, the extractograms generally support previous suggestions of the likely forms or associations of As present in the different soil fractions.

Geochemical Exploration on the Stream Sediments of Gabal El Mueilha Area, Central Eastern Desert, Egypt: An Overview on the Rare Metals

Abstract: El Mueilha area consists of post‐collision granitic rocks intruding Pan‐African metasediments, metavolcanics and granodiorites. Tin mineralization in Gabal El Mueilha is either of vein type or disseminated in the greisenized and albitized parts of the granitic rocks. Cassiterite and wolframite‐bearing quartz veins also characterize a small intrusion of muscovite granite at El Mueilha tin mine area. Detailed geochemical prospecting for the rare metals Sn, Nb, Be, Li, U, Th and some other trace elements was carried out at Gabal El Mueilha area using stream sediments survey. Sixty‐seven stream sediment samples were collected from the main drainage patterns of the study area. Statistical parameters were calculated for the analyzed elements. The sought elements Sn, Nb, Be and Li have relatively high background values in the studied sediments. This may reflect the role of the pathfinder elements (Nb, Be and Li) during secondary dispersion survey for Sn mineralization.Geochemical maps were constructed to delineate anomalous areas with abnormally high rare metal contents. The anomalous Sn, Nb and Be areas are mainly encountered in the main stream draining the mineralized zones of El Mueilha tin mine and near the SW albitized parts of the post‐collision granite. Correlation coefficient matrices show significant positive relation between Sn and the rare metals group (Nb, Rb and Li) at 99 % significant level. R‐mode factor analysis for the concerned elements yields five factor–model.

Water quality studies in an aquatic environment of disused tin-mining pools and in drinking water

Large areas of abandoned tin-mining pools have found secondary uses which provide natural habitats for aquaculture activities where most freshwater fishes are bred. Soils from tin-mining areas are rich in uranium and thorium. A study has been conducted on the status of waters and aquatic habitats in disused tin-mining pools and at water intake points for public drinking water supply to assess the presence of natural radionuclides and arsenic which are potential health hazards. The concentrations of uranium and thorium were determined by gamma spectrometry. Arsenic species were preconcentrated with ammonium pyrrolidinedithiocarbamate in chloroform and were later irradiated in a neutron flux of 5.1×10 12 n cm −2 s −1 of a TRIGA Mk.II nuclear reactor to induce radioactivity due to the 76As radionuclide. The concentrations of uranium were found to be relatively lower than thorium whereas the As(III) species have almost similar concentrations with the oxidized form of As(V). The determination of radium from water samples taken from water intake points as well as treated water was done by co-precipitation separation with mixed barium carrier followed by reprecipitation using sulphuric acid. Results obtained showed that the average concentration of 226Ra for raw water is 3.34 pCi l −1 compared to about 0.89 pCi l −1 for treated water samples. These figures are well below the maximum permissible level of 5 pCi l −1 for drinking water.