The impact of small-scale mining activities on the levels of mercury in the environment: The case of Prestea and its environs

To obtain the baseline information of mercury pollution due to gold mining activities in Prestea and its environs total mercury (T-Hg) concentrations were measured in water and stream sediment. The samples were analyzed by instrumental neutron activation analysis (INAA). They were irradiated and counted without any preconcentration. Higher levels of T-Hg concentration were found in samples at the sites with extensive small-scale galamsey gold mining activities than at the sites with low small-scale galamsey activities. Concentrations varied between 6.80–19.82 mg/l for water and 28.90–84.30 mg/kg in sediment at sites with extensive small-scale mining activities. At low small-scale mining sites concentration levels for T-Hg varied between 0.50–9.10 mg/l and 1.20–22.75 mg/kg in water and sediment, respectively. The concentration levels of T-Hg in water from all the sampling sites are in excess of the WHO tolerable limit of 0.001 mg/l for drinking water.Some financial support for the work from the National Nuclear Research Institute is highly appreciated. The authors thank Messers Nick Opata and Ekow Quagraine, the technicians at the NAA laboratory for their contribution during preparation, irradiation and counting of samples. We also thank the team of reactor operators.     

The importance of tin in the environment and its determination at trace levels

Summary A review on the behaviour of tin in the environment is given. Biological effects (essentiality, toxicity) as well as distribution and transport processes of tin are strongly dependent on the kind of chemical species present. Methods for the determination of tin and tin compounds (e.g. organotin compounds) at trace levels are discussed. Especially, sources of systematic errors and interferences are considered.

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Die Bedeutung des Zinns in der Umwelt und seine Bestimmung im Spurenbereich

Zusammenfassung Ein Überblick wird gegeben über das Verhalten von Zinn in der Umwelt. Sowohl Wechselwirkungen mit biologischen Systemen (Essentialität, Toxizität), als auch Verteilungs- und Transportprozesse des Zinns sind stark abhängig von der Art der vorliegenden Zinnspezies. Möglichkeiten zur analytischen Bestimmung von Zinn und Zinnverbindungen (z.B. Organozinnverbindungen) im Spurenbereich werden dargestellt und diskutiert. Dabei werden besonders Quellen für systematische Fehler und Störungen berücksichtigt.

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Dedicated to Prof. Dr. R. Bock on the occasion of his 70th birthday     

The importance of tin in the environment and its determination at trace levels

Analytical and Bioanalytical Chemistry - A review on the behaviour of tin in the environment is given. Biological effects (essentiality, toxicity) as well as distribution and transport processes of...     

Detoxification of mercury in the environment

In this study, a green chemistry approach was developed as an option for remediation of toxic mercury in the environment. Twenty mercury compounds were treated with an environmentally friendly agent cyclodextrin to produce stable non-toxic mercury in soil and water. The binding efficiency was determined using high performance liquid chromatography with diode-array detection. The stability of the cyclodextrin mercury complexes toward environmental microorganisms in water was estimated under OECD guidelines using gas chromatography–mass spectrometry. The toxicity of the cyclodextrin mercury compounds to terrestrial organisms was investigated by use of internationally recognized toxicity methods using mercuric acetate as a model contaminant. Key process conditions, for example pH, temperature, and amount of detoxifying agent were investigated and found to have significant effects on the toxicity of mercury. It was found that organic and inorganic mercury pollutants could be mineralized in the environment with cyclodextrins. The bound mercury compounds resisted biodegradation and were found to be non-toxic to environmental microorganisms under laboratory conditions.     

The use of neutron activation analysis in gold prospecting in small-scale mining in Ghana

A set of rock and soil samples from Dome Beposo in the Amansie-West district of Ashanti Region of Ghana, suspected to contain gold, have been analyzed using instrumental neutron activation analysis (INAA) coupled with conventional counting techniques. The identification and quantification of the elements, gold, arsenic, mercury and antimony were done using 411.8 keV photopeak of ¹⁹⁸Au, 559.1 keV photopeak of ⁷⁶As, 77.3 keV photopeak of ¹⁹⁷Hg and 564.2 keV photopeak of ¹²²Sb. The precision and accuracy of the method were evaluated using standard reference materials. The precision and bias was found to be less than 6%. The first set of samples consists of ten rocks (GS), four of which retain moderate to quite high concentrations of gold, 0.27±0.01 mg/kg, 1.58±0.09 mg/kg, 7.51±0.44 mg/kg and 8.06±0.35 mg/kg, respectively. The second set comprises two soil samples taken from the upper and bottom layers of a gold exploration pit. Gold concentrations in upper (UL) and bottom (BL) layers are 0.06±0.002 mg/kg and 0.47±0.02 mg/kg, respectively. Arsenic was found in the soils as well as the rocks, and the levels ranged from 9.3±0.5 to 274±15.6 mg/kg. Mercury and antimony were found in the rocks only. Mercury levels in the rocks ranged between 0.11±0.004 and 9.67±0.42 mg/kg whilst antimony levels ranged from 0.21±0.01 to 6.88±0.38 mg/kg. This revised version was published online in July 2006 with corrections to the Cover Date.     

Overview of SM & T (BCR) activities for the quality control of mercury determination in the environment

The aim of the Standards, Measurements and Testing Programme (SM & T) of the European Commission (continuation of the BCR and Measurements and Testing Programmes) is to contribute to the harmonisation and improvement of methods and measurements carried out within the European Union and hence to the comparability of data necessary for e.g. trade activities, monitoring of environment, food and health, etc. R & D projects along these lines are currently funded; in the field of environmental analysis, they consist in most cases in the organisation of interlaboratory studies (intercomparisons and certifications of reference materials) in which laboratories may collaborate to improve the measurement or analysis concerned. Other activities are related to development of new methods and pre-normative research. This paper describes the objectives of the SM & T programme and the main actions undertaken, and gives examples of projects dealing with mercury determination in environmental matrices. Received: 24 September 1996 / Revised: 19 January 1997 / Accepted: 24 January 1997     

Overview of SM & T (BCR) activities for the quality control of mercury determination in the environment

The aim of the Standards, Measurements and Testing Programme (SM & T) of the European Commission (continuation of the BCR and Measurements and Testing Programmes) is to contribute to the harmonisation and improvement of methods and measurements carried out within the European Union and hence to the comparability of data necessary for e.g. trade activities, monitoring of environment, food and health, etc. R & D projects along these lines are currently funded; in the field of environmental analysis, they consist in most cases in the organisation of interlaboratory studies (intercomparisons and certifications of reference materials) in which laboratories may collaborate to improve the measurement or analysis concerned. Other activities are related to development of new methods and pre-normative research. This paper describes the objectives of the SM & T programme and the main actions undertaken, and gives examples of projects dealing with mercury determination in environmental matrices. Received: 24 September 1996 / Revised: 19 January 1997 / Accepted: 24 January 1997     

Fallout from Chernobyl in Bologna and its environs: Radioactivity in airborne,rain water and soil

The Chernobyl fallout was estimated in Emilia-Romagna, a Northeastern region of Italy. Nuclide composition of airborne and the time evolution of the radioactivity were investigated. The comparison of the activity ratio of¹⁰³Ru to¹³⁷Cs allows to conclude that Italy was not influenced by the first release. The trend of the total activity and¹³⁷Cs percentage in rain water was very similar to those of air particulates. A calculation model to estimate¹³⁷Cs deposition onto the ground has been developed and validated by comparison of the calculated and experimental values for soil samples. The activity range was 2–40 kBq ·m^–2.     

Preparation of a gold electrode modified with tri-n-octylphosphine oxide and its application to determination of mercury in the environment

A gold film electrode modified with a film of tri-n-octylphosphine oxide (TOPO) in a PVC matrix has been prepared and tested. Cyclic voltammetric experiments have shown that the electrode is useful for highly selective voltammetric determinations of a number of metals, primarily Hg, Cr, Fe, Bi, Sb, U and Pb. The electrode has been applied to the anodic stripping voltammetric determination of mercury in some environmental samples, such as river sediments. Concentrations of 0.02-50 ppm of mercury can be determined with good precision and accuracy, as demonstrated by analyses of reference materials. A selective decomposition of the samples at laboratory temperature decreases the danger of sample contamination and of volatilization of mercury.     

The determination of total gaseous mercury in air at background levels

A method is described for the determination of the total gaseous mercury in air at concentrations ranging from ca. 0.1 ng m^-3 to 1μg m^-3. The method is based on the collection of mercury species on gold-coated quartz wool followed by detection with an atomic absorption detector. The collection efficiencies for mercury, dimethylmercury, methyl-mercury(II) chloride, and mercury(II) chloride are nearly quantitative at flow rates up to 10 1 min^-1 and at temperatures up to 50°C. The absolute detection limit of the method is 20 pg of mercury. Under field conditions the precision of the analytical procedure was 14.5% (n=5) for 400-l samples of air and a mercury concentration of 1.5 ng m^-3. Measurements of the mercury distribution in the atmosphere show an ambient background level in clean air masses of 1.0–4.0 ng m^-3.     

The impact of lead pollution on the environment of Rabat-Sale' (Morocco)

There are numerous possible vectors of industrial lead poisoning in unprotected work environments and the areas surrounding industrial sites. In the Rabat-Salé region, ceramics is the industry which uses most lead. Galena (PbS) is used in the fabrication of some types of pottery, and other lead-based compounds are used as glaze. A second source of lead pollution is the production of some fuels, in which lead is used as an anti detonator. In order to evaluate the impact of lead contamination on the environment, our investigation is focused on the lead concentration in the atmosphere, soil and vegetation at five stations in the Rabat-Salé region. We found concentrations of lead higher than those published for any other country in the atmosphere and vegetation near the ceramics factories of Rabat-Salé. These concentrations decreased significantly as we moved away from urban areas.     

The impact of the actual geometrical structure of a thermoelectric material on its electronic transport properties: the case of doped skutterudite systems

By doping CoSb(3) with Sn, Ba, and La, several structural outcomes are possible. The effect these different structures have on the electronic transport properties of the resulting materials is evaluated by means of an ab initio electronic structure approach and by using the semiclassical Boltzmann theory to derive the electronic transport properties from the band structure. It is shown that the calculated Seebeck coefficient is a very useful indicator of both the actual content of the dopant element and of where it mainly locates into the CoSb(3) structure. The use of such an indicator, along with geometrical considerations, demonstrates that the Sn atom occupies both the interstitial and the pnicogen ring positions with relative occupancies and ensuing thermoelectric properties, which heavily depend on the synthesis' conditions. The same indicator also suggests that the La atom, which occupies only interstitial positions, has a far lower maximal solubility in CoSb(3) than that claimed experimentally.     

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

Cellulose - In an enzymatically driven lignocellulosic biorefinery, pretreatment and hydrolysis modules are the two most significant cost contributors for obtaining high gravity sugar solutions....     

Electrosorption of vitamin K1 at mercury and its determination at submicrogram levels by differential pulse voltammetry at a hanging mercury electrode

The electrochemical behaviour of vitamin K₁ has been studied in ethanolic and methanolic acetate buffers by cyclic voltammetry and differential pulse voltammetry (d.p.v.) at the h.m.d.e. and differential pulse polarography at the d.m.e. Increased adsorption occurs at the mercury electrode as the percentage of water is increased. The most sensitive signal was obtained by d.p.v. with acetate-buffered 60% methanolic solutions; vitamin K₁ could then be measured down to 10 ng ml^-1.     

Theory of cyclic voltammetry at the mercury film electrode: Reversible case with substrate initially present in the mercury phase

The theory of cyclic voltammetry has been developed for a case describing the behaviour of a reversible system at the mercury film electrode with a metal present initially in the mercury phase. Theoretical results are presented in the form of a simple equation coupled with a set of the calculated current function values. In addition, several simple relationships are given for the parameters characterizing the cyclic curves. The rapid exhaustion of the metal from the mercury film and the generation of the metal ions into the solution free of metal ions offer better conditions for the resolution of adjacent peaks than those existing in cyclic voltammetry at the HMDE and at the MFE with substrate present initially in solution. Theoretical predictions were compared with experimental results obtained for lead and thallium at the silver-based mercury film electrode.     

Influence of acid mining activity on release of aluminium to the environment

An optimized BCR three-step sequential extraction procedure, several single extractions and the reactive aluminium determination after chelating ion-exchange on Iontosorb Salicyl were used for the fractionation of Al in soil samples from a mining area with sulphidic deposits. The aluminium amounts released by used extraction procedures were valuated and discussed. The new indicative values of fractional Al concentrations in five Chinese certified reference materials (GBW 07103, 07304, 07401, 07405, 07407) were determined after Al fractionation by optimized BCR three-step sequential extraction procedure. The aluminium toxicity indexes calculated for two different soil extracts and plant samples were used for assessment of Al toxicity to plants. It can be concluded that the most sensitive indicator of increasing aluminium toxicity to plants is determination of reactive Al species in soil solution by chelating ion-exchange solid phase extraction.The atomic absorption spectrometry with nitrous oxide-acetylene flame was used for determination of total Al amounts and the Al concentration in different extraction fractions as well.     

Environmental impact assessment of post illegal mining activities in Chini Lake with regards to natural radionuclides and heavy metals in water and sediment

Journal of Radioanalytical and Nuclear Chemistry - Comprehensive radiological survey and evaluation of heavy metal contamination were conducted in Chini Lake, which has been awarded a pristine...     

磁性凹凸棒土制备及其脱汞性能研究

对自然界中广泛存在的凹凸棒土(Atp)进行磁改性,通过沉积-沉淀法制备出磁性氧化铁改性的磁性凹凸棒土(MAtp),采用BET、VSM、XRD以及SEM等手段对其理化性质加以分析,并在固定床实验台上进行模拟烟气脱汞性能测试,研究了铁氧化物含量、反应温度和烟气成分对其除汞能力的影响。结果表明,Atp与磁性物质的复合提高了其对Hg~0的脱除能力,并且随铁氧化物含量升高,MAtp脱汞能力逐渐增强;在实验温度区间内,脱汞能力随温度的升高逐渐增强,MAtp对Hg~0以化学吸附为主;O_2、NO的添加有利于Hg~0的脱除,但Hg~0穿透率随浓度变化不显著;SO_2抑制汞的脱除,并且随浓度的增加,其抑制效果更加明显,但是当NO和SO_2共同存在时,NO能明显削弱SO_2对脱汞的抑制作用。