[en] This is the first comprehensive health evaluation made by the Department of Health of the mining community's exposure to total and methyl mercury. Previous studies have mainly focused more on the health risks associated with occupational exposure to mercury. Other sources of mercury exposure such as diet and other environmental media was not investigated and the population studied did not include high risk groups such as pregnant women and children

[en] During the reporting period work three main topics have been addressed in order to achieve the objectives of the CRP: 1. Methylmercury formation and degradation in sediments of the Gulf of Trieste. 2. Preparation of SOIL-1 intercomparison sample. 3. Validation of techniques for determination of the rates for methylation and demethylation of mercury in various matrices. The present report covers the first two topics, while the third is presented as a separate manuscript in this report, dealing with methylation of mercury in Isopod Porcellio scaber and in lichens. (author)

[en] Full text: Highlights and achievements: Relationship between atmospheric mercury and plant leaves mercury content Hg in plants came both from soil and the atmosphere. On the whole, 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. (author)

[en] Lichens have long been regarded as a suitable tool for monitoring the relative levels of atmospheric pollutants. Lichens have neither roots, a waxy cuticle nor stomata: hence, for mineral nutrition they are largely dependent on wet and dry deposition from the atmosphere. Moreover, lichens are perennial and can accumulate elements over long periods of time. Therefore, concentrations of elements in lichens represent the average levels of elements in the atmosphere for a long period of time. The epiphytic lichen Hypogymnia physodes is a good bioindicator of air pollution with total mercury (THg). In addition, it contains small amounts of methylmercury (MeHg⁺). The first aim of our work was to test analytical techniques for determination of MeHg in lichens taken from different locations in Idrija and reference locations

[en] Mercury is a highly toxic non-essential element. The mercury cycling in natural environments is a complex process. In recent years, the stable mercury isotope tracer and related analytical techniques have been developed. They offer unique possibility to understand the biogeochemistry of mercury in various environmental conditions. So a new coordinated research project (CRP), on health impacts of mercury cycling in contaminated environments studied by nuclear techniques, has been supported by the IAEA. This paper introduces the research project which is IAEA research contract number CPR-10874. It includes the scientific background, scope of the project, methods, some results related to this CRP and the plans for future work. (author)

[en] The environmental and atmospheric samples i.e. surface water, ground water, surface soil, sediment, rain and fog from various sites of contaminated environments of central India were collected in year, 2000-2001. The concentration levels of total-Hg in these samples were analyzed by using techniques i.e. cold vapor- atomic absorption spectrophotometer (CV-AAS), X-ray fluorescence spectrophotometer XFS). Further, the data base of total Hg in the environmental samples would be validated in other laboratories i.e. Prof Dr. Klaus Heumann (Johannes Gutenberg-University, Mainz, Germany), David Amouroux (University of Pau, France) and Dr Joerg Feldmann (University of Aberdeen, Scotland, UK) for exploration of the Hg-contaminated environments by using techniques i.e. ICP-MS/GC, gas chromatography-induced couple atomic emission spectrophotometer (GC-ICP-AES), neutron activation analysis (NAA). (author)

[en] Activities at mercury (Hg) mines can lead to the mobilization of large quantities of Hg that enter the environment and are transported downstream. Although much of this Hg is deposited near the source, over time much of this Hg can be carried hundreds of kilometers where it can potentially enter and bioaccumulate in distant food webs. Mining activities in the ldrija, Slovenia mining district occurred for 500 years and the legacy of that mining can be seen in high concentrations of Hg throughout the watershed and into the Gulf of Trieste. Mercury concentrations are high in the sediments near the mouth of the Soca/Isonzo, River in the Gulf, and the Soca River continues to deliver ∼1.5 tons of Hg to the marine environment ∼100 km from the mine. Much of the Hg carried to the sea is probably as fine cinnabar particles, and the potential remobilization and further transformation of this Hg is of concern with regard to local environmental and the accumulation of methylmercury (MeHg in seafood. Mercury sulfide minerals are subject to dissolution and increased bioavailability when they contact sulfidic environments such as what occurs in coastal marine sediments. This 'newly' available Hg can potentially undergo methylation to supply the environment with newly formed MeHg. Indeed, Gulf sediments contain significant concentrations of MeHg and effluxes of MeHg from Gulf sediments have been observed in recent studies. However, sediments can also support active demethylation by aerobic and anaerobic bacteria. This demethylation can be due to either oxidative or reductive pathways. The present study was conducted to determine the potential of sediments from the Gulf of Trieste to methylate and demethylate Hg including an assessment of which demethylation pathway is most prevalent

[en] The development of a combined mercury extraction - speciation technique for total mercury and methylinercury determination in various biological and environmental media have been established to study and evaluate environmental factors influencing the dynamics of mercury in aquatic systems. Comparability studies of the results from the conventional and radiochemical techniques were planned for the 1st year of the CRP. Validation of the radiochemical method will be undertaken during the current CRP because of constraints in obtaining the appropriate radiotracers. The use of radiotracer techniques will be undertaken to investigate the generation and distribution of methylmercury in the river water - sediment systems using ²⁰³Hg. The improved conventional analytical procedure uses the cold vapor atomic absorption spectrometry for the determination of total mercury in biological and environmental samples. For methylmercury determination, samples are analyzed using combined techniques of dithizone extraction and gas chromatograpy with electron capture detection

[en] Measurements of net ²⁰³Hg methylation potentials were made in a set of floodplain lakes of the Tapajos river, Brazilian Amazon, on roots of the floating macrophyte Paspalurn sp. during the wet and dry seasons. Water physico-chemical parameters and C, N, and C and N isotopic ratios on root -associated periphyton were also determined. We confirmed the high Hg methylation potentials in roots of Paspalurn sp. and other macrophyte species (up to 22%) but observed that the intra and inter-lake variations in root methylation potentials are high, even when sampling one single macrophyte species. Correlations between Hg methylation in roots of Paspalurn sp and other measured parameters are low, possibly due to the limited data set available so far. Other tracer techniques have been recently introduced in this study, such as measurements of bacterial activity estimated by tritiated leucine uptake and sulfate-reduction measurements ³⁵S0₄ uptake, and it is expected that they will contribute to the understanding of the environmental parameters controlling Hg methylation in the studied water systems. (author)

[en] Full text: Highlights and achievements: We confirmed that high methylation potentials (up to 22%) are found in roots of Paspalum repens and other floating macrophyte species such as Eichhomia crassipes and Ludwigia helmynthoryza during both phases of the hydrological cycle, with a tendency for higher values in the wet season, confirming findings of previous studies, and a strong intra and interlake variation. Hg methylation in macrophyte roots is carried out mainly in the root-associated periphyton a complex and variable assemblage of benthic microalgae, fungi, bacteria and organic and inorganic detritus. However, no significant correlation was found in the first campaign between Hg methylation in samples of Paspalum sp. roots and the amount of periphyton in these samples. We also verified that total plankton and phytoplankton are sites of a low < I %) but easily detectable methylation. Simultaneous in-situ determinations of Hg methylation potentials, bacterial activity and sulfate-reduction activity were made in the frame of this project, probably for the first time in tropical aquatic environments. Preliminary analysis of data by the other research teams involved in the project suggest that the influence of terrigenous inputs on the Hg loads and cycling in the local aquatic environments may be hard to pinpoint, considering the moderate magnitude of these inputs in comparison to the inputs of the Tapajos river and the intense dynamics of the lakes themselves. Pitfalls: Heavy official bureaucracy and delays for issuance of permits for joint scientific expeditions involving foreigners in the Amazon, export of samples (except by mail) and for custom clearance, aggravated by biopiracy concerns; Increasing difficulties in obtaining commercial ²⁰³ Hg; Basic infrastructure problems caused partial loss of samples in one of the campaigns. (author)