[en] The research carried out included three topics: analytical development, methylation of mercury in terrestrial isopods, and distribution of Hg in the Idrijca and Soea river system. (author)

[en] High mercury levels in carnivorous fish at the Guri reservoir located at the southeastern of Venezuela in the State of Bolivar point toward the presence of a bioaccumulation process in this reservoir. It was necessary to identify and classify development unities in settlements nearby reservoir Guri according to their use, due to the lack of up-to-date demographic information. The total mercury concentration in 7 sediment samples from reservoir Guri ranged from 0.0281 to 0.0877 High mercury levels in carnivorous fish at the Guri reservoir located at the southeastern of Venezuela in the State of Bolivar point toward the presence of a bioaccumulation process in this reservoir. It was necessary to identify and classify development unities in settlements nearby reservoir Guri according to their use, due to the lack of up-to-date demographic information. The total mercury concentration in 7 sediment samples from reservoir Guri ranged from 0.0281 to 0.0877 μg/g while methyl mercury levels oscillated from 0.15 to 3.45 ng/g. A total of 33 fish samples were analyzed; in general, according to the remarks on mercury levels the values ranged from very low to high. Ninety seven percent of fish samples had total mercury concentrations below 0.5 μg/g which is the guideline recommended by World Health Organization for human consumption; however, it was found in a sample from the carnivorous trophic level a total mercury concentration of 3.56 μg/g (Hydrolicus scomberoides, common name 'Payara'). Ninety-eight hair samples were collected from the exposed group, the highest mean concentration of mercury was found in 'Los Guacos' (12.82 μg/g) and it was higher than the mean value of the non exposed group (1.62 μg/g; n = 23). A total of 28 cases of the exposed group had hair mercury concentrations above 6.0 μg/g. It was found significant difference between the exposed and non exposed groups (p= 0). A pre-impoundment sampling was carried out in the flood area of reservoir 'Caruachi'. Eighty-three soil samples were gathered for mercury analysis, the total mercury concentration ranged from 0.1 to 367 μg/g. There was a wide variability among samples; however, such high values may chiefly have some relationship to mining - intensive operations that were carried out in the area for more than 30 years. To analyze the spatial structure of mercury levels in soil a semi variance analysis was applied to confirm autocorrelation of the variable. It was found a well-localized gradient of mercury concentrations; however, mercury levels were spatially too disperse on a wide sector and punctual in others. (author)

[en] The central region, Chhattisgarh state of India is rich in deposition of minerals i.e. lime stone, iron-ore, copper-ore, rock phosphate, manganese ore, bauxite, asbestos, etc. and coal. More than 50 million tones (MT) minerals and coal are exploited every year by various industries and thermal power plants to produce metals, alloys, cements and energy in this part of the country. In addition, > 600 rice mills are in operation to produce > 2 MT rice every year. These raw materials are contaminated with various very toxic metals i.e. As, Hg, Pb, etc. at trace levels. The processes i.e. mining, burning of coal, smelting of minerals, milling of rice, etc. are expected main emission source for the toxic metals. To understand the mercury cycling and health hazard in this region, the surface water of the contaminated sites and waste water of point sources (i.e. thermal power plant, steel plant, cement plant, sulfuric acid plant, rice mill, etc.) have been analyzed. In forty-two samples, the concentration of total mercury levels was in range of 6.7 - 678 ng/ml with mean and median value of 118.1 and 49.3 ng/ml, respectively. The strongest sources for mercury emission in this region observed were leaching process from coal and iron pyrite and coal burning. In order to know the mercury health impact in the humans living in the contaminated sites, twenty hair samples have been analyzed. The total mercury level was ranged from 2.6 - 37.8 mg/kg with mean and median value of 12.3 and 10.4 mg/kg, respectively. The mercury health hazard in this region expected are owing to mercury exposures and use of mercury contaminated water and foods. A detailed investigation is needed to understand the human health effect of mercury in this region of country. (author)

[en] Research work concentrated on the following field and/or laboratory investigations: i) assessment of Hg contamination levels in selected environmental media in the Lake Victoria goldfields, ii) the study of lichens as a suitable bioindicator for atmospheric Hg contamination in small-scale gold mining areas, iii) dynamics of Hg transformation and partition of Hg species in gold mine tailings-water systems contaminated with elemental mercury, iv) mineralogical and chemical characterization of mine tailings, river sediment, lateritic soils in relation to Hg mobility under tropical conditions, v) the effect of aeration/oxygenation and decrease of moisture content on MeHg levels in tropical soil and, iv) methylation of Hg in SOIL-1 inter-comparison sample from the IAEA. Hg contamination was highest in gold mine tailings (165-232 μg/g) from amalgamation ponds but relatively low in contaminated river sediments (6-0.5 μg/g) in the study areas. The dispersion of Hg in river sediments at the Mugusu mine decreased rapidly from 6 μg/g near the gold ore processing site to <0.1 μg/g about 9 km downstream. The highest Hg levels were associated with the grain-size fraction <212 μm in the sediments. Fish mercury levels in 8 fish species representing different trophic levels from the Nungwe Bay in the Victoria lake were generally low, <50 ng/g (w.w.), which indicated insignificant levels of contamination and/or little bioavailability of Hg in that lake region. Mercury concentrations in the Parmelia lichen from Mugusu, Imweru, Rwamagaza and Buckreef gold mine areas, southwest of the Lake Victoria, ranged from 3.1 to 0.07 μg/g, the highest concentrations being recorded close to gold processing stations. The lichens from areas outside the goldfields had the lowest Hg levels in the range 0.05-0.10 μg/g (mean 0.07 μg/g). Investigations of Hg transformation in gold mine tailings from the Rwamagaza mine revealed exceptionally high MeHg contents (629-710 ng/g as Hg), which indicated that methylation occurred at significant levels in the tailings under tropical conditions. The MeHg was so firmly bound in the tailings that very little MeHg was partitioned to water (0.2-1.5 ng/L) re-equilibrated with the tailings. X-Ray diffraction (XRD) analysis showed the tailings to consist mainly quartz and dolomite, and accessory amounts of clinochlore and talc. Results for SOIL-1 analysis and other laboratory investigations are also presented in the report. (author)

[en] Conservative estimates of global natural mercury fluxes into the atmosphere suggest a total of 500 t/a originating from the mercuriferous belt and about 200 t/a degassing from background soils. Recent flux measurements at different terrestrial sites suggest that mercury emissions and re-emissions from terrestrial sites have been significantly underestimated. This could result in an inaccurate ratio between natural and anthropogenic sources in global emission inventories. However, all this estimates are based on a fairly raw database, and considering that, it becomes clear that an accurate assessment of air/surface exchange processes will be critical to refine the global mercury cycle. For upscaling mercury fluxes derived from field experiments to regional or global scales a detailed process understanding of the driving forces behind air/surface exchange is imperative.We studied the influence of environmental parameters on mercury fluxes for 8 different soils

[en] In recent decades, the production and using of mercury was reduced, however, the mercury pollution and health impacts are still serious. It is because that China's economy was forging rapidly ahead in the past 20 years. The combustion of fossil fuels, in which of the coal is more than 70% in the total energy consumption, was increasing year after year, especially in some industrial cities. So a co-ordinated research project (CRP), on health impacts of mercury cycling in contaminated environments studied by nuclear techniques, has been supported by the IAEA. In the CRP that contract number is PRC-10874, some research techniques for understanding the behavior of mercury in terrestrial ecosystem were developed, and some problems about mercury pollution in terrestrial ecosystem and their impacts have been probed. The results indicated that because of the increasing of anthropogenic Hg emission, the Hg accumulation in terrestrial ecosystem was increasing with time in the research sites (Chongqing, China), which Hg in wet and dry deposition was sum 195.3 g/km²·yr in urban and 48.5 g/km²·yr in rural area. The bioaccumulation of Hg in plant was related to the concentration of atmospheric Hg and soil Hg. The Hg content of plant increased with the atmospheric Hg increasing. Hg contents in plant leaves increased with the increase of air-Hg, the correlation equation was: y 0.0173x-0.3204 Calculation from this equation showed that the accumulation of Hg in plants stemmed mainly from soil rather than atmosphere when air-Hg was lower than 18.5 ng/m³, however contribution of air-Hg to plant Hg accumulation was increasing with the increase of Air-Hg when its concentration was higher than 18.5 ng/m3. Furthermore, it was found that Hg content in some crops and livestock products had exceeded the limit of FHSV due to Hg accumulation in terrestrial ecosystem increasing gradually with the increasing Hg emission in Chongqing. It should be noted specially that the Hg concentration of milk was higher, some of it was in excess of the limit of Food Health Standard Value (FHSV) because of high Hg accumulation in forages. The investigation data of the mercury in fishpond systems in the research sites indicated that the accumulation of mercury in fishponds in polluted sites was much higher than that in control site. So the content of Hg in fish muscle in polluted sites was higher than in control site. The content of Hg in all the fish muscle in heavy pollution site exceeded the limit of FHSV for Hg in fish (0.3 mg/kg FW). The contents of mercury in muscle of fish from the Yangtze River were lower than the FHSV, but some data from the reservoirs were higher than the FHSV. All the I/O values, the ratios between the input of output of mercury in soil in vegetable land system in different acid deposition areas, in the acid deposition areas were more than 1, it means that there was accumulation of mercury in soil in the regions. The Hg content in surface soil increases average 0.567μg/kg a year in heavy pollution area, but only 0.00907μg/kg in control area. It implies that the Hg accumulated in soil more and more badly in heavy pollution area, it will influence the human health through the food chain. (author)

[en] Mercury and its compounds are toxic to man and his environment. The toxicity of mercury is dependent on the species i.e. elemental, inorganic and organic forms. The general population may be exposed through occupational and environmental sources. In the Philippines, two major sources of mercury contamination were studied namely small-scale gold mining activities utilizing mercury and pollution brought about by mine tailings in a former mercury mines. Small-scale mining in this report is defined as artisanal operations, labor intensive, low level mechanization using crude methods of mining, extraction and refining procedures. Women and children usually participate in these activities. In another island in the Philippines, a mercury mine was operational from 1955 to 1976 producing about 140,000 kg of mercury yearly. Approximately 2,000,000 tons of mine-waste calcines (retorted ore) were produced during mining and roughly 1,000,000 tons of these calcines were dumped into nearby Honda Bay to construct a jetty to facilitate mine operations where about 2,000 people reside in the nearby three barangays. At present the effects of total mercury exposure combined with Me-Hg consumption remain an important issue especially those of low-dose and continuous uptake. However, information on the effects of low and prolonged exposure of total and methylmercury to offspring throughout their prenatal and postnatal periods have been limited. This study will compare possible health risks of lower level at chronic exposure to total and methylmercury in communities situated near a former mercury mine and a control group with minimal or limited exposure. (author)

[en] Mercury is a global pollutant because of its ability to undergo long distance transport into the atmosphere. In view of these global concerns the IAEA has organised a CRP to elucidate the biological, chemical, and physical factors, which influence the transformations of Hg and its compounds in the ecosystem and the dynamics of the mercury recycling. Under the title 'Health impacts of mercury cycling in contaminated environments studied by nuclear techniques' the CRP was started in October 1999 and concluded in February 2004. This report provides an overview of the various activities performed under the CRP by the various participants. The overall achievements are summarized and those aspects that require a further deeper look are also pointed out. The individual country reports are also given which detail on the progress made by the respective participants, during the CRP period. It is hoped that the results would encourage further research activities on these and related issues in the respective countries with the CRP participant as a catalyst to further these studies

[en] Mercury is a global pollutant because of its ability to undergo long distance transport into the atmosphere. In view of these global concerns the IAEA has organised a CRP to elucidate the biological, chemical, and physical factors, which influence the transformations of Hg and its compounds in the ecosystem and the dynamics of the mercury recycling. Under the title 'Health impacts of mercury cycling in contaminated environments studied by nuclear techniques' the CRP was started in October 1999 and concluded in February 2004. This report provides an overview of the various activities performed under the CRP by the various

[en] Environmental mercury contamination is an issue of deep concern in tropical and other regions. In particular, a number of countries in the tropical belt of South America, Africa and Southeast Asia have experienced tremendous increase in uncontrolled small-scale gold mining using mercury amalgamation since early 1980s, which is likely to amplify adverse effects on the contaminated ecosystems and cause health hazards. Ecologically, the most critical but complex part of the mercury pollution problem is that concerned with the transformation of inorganic mercury into more toxic mono-methylmercury(MeHg) that is more biologically available for aquatic organisms. Although increasing literature dealing with mercury contamination levels in human populations and in aquatic ecosystems exists, we are still unable to make predictions of the behavior of mercury in the aquatic systems, particularly under the tropical conditions. Thus, it is imperative to obtain basic data concerning the overall dynamics of MeHg production, as well as the environmental factors influencing mercury methylation and the partitioning of mercury in the aquatic systems in order to understand and predict the cycling and bio-accumulation of mercury. To facilitate studies on the dynamics of mercury in the aquatic systems, we have developed highly sensitive and systematic methods for the analysis of total mercury(T-Hg) and MeHg in a wide range of biological and environmental materials containing mercury down to background levels. With these methods, it is now possible to make quantitative measurements of the equilibrium distribution or partitioning of MeHg produced in sediments in a model of aquatic systems under various environmental conditions similar to those found in the fields. Such an approach should undoubtedly help elucidate the mechanisms of mercury pollution in the tropical ecosystems and promote efforts in mercury pollution prevention. (author)