U and Th in some brown coals of Serbia and Montenegro and their environmental impact

GOAL, SCOPE AND BACKGROUND: The objective of this paper is to determine and compare the concentrations of U and Th in soft to hard brown (lignite to sub-bituminous) coals of Serbia and Montenegro. It also presents comparison of the obtained data on U and Th concentrations with the published data on coals located in some other countries of the world. Almost the whole coal production of Serbia and Montenegro is used as feed coals for combustion in thermal power plants. METHODS: Channel samples from open pit and underground mines and core samples were collected for hard and soft brown coals. For the analysis the samples were decomposed using microwave technique. Obtained solutions containing U and Th were analyzed by inductively coupled plasma mass spectroscopy (ICP-MS) using NIST standards. RESULTS: Concentration of U from the investigated basins and the corresponding mine fields ranges within 0.60-70.10 mg/kg, 0.65-3.20 mg/kg, 0.95-6.59 mg/kg, 1.20-6.05 mg/kg, 0.80-6.66 mg/kg, 0.18-89.90 mg/kg, 0.19-4.14 mg/kg, and 0.28-3.52 mg/kg for the Kostolac, Kolubara, Krepoljin, Sjenica, Soko Banja, Bogovina East field, Senje-Resavica and Pljevlja basins, respectively. Concentration of Th ranges within 0.20-2.60 mg/kg, 0.84-6.57 mg/kg, 1.48-6.48 mg/kg, 0.12-2.71 mg/kg, 0.13-4.95 mg/kg, 0.14-3.48 mg/kg, 0.29-3.56 mg/kg, and 0.17-1.89 mg/kg for the Kostolac, Kolubara, Krepoljin, Sjenica, Soko Banja, Bogovina East field, Senje-Resavica and Pljevlja basins, respectively. DISCUSSION: Brown coal from Senje-Resavica, Kolubara, Kostolac and Pljevlja is characterized by low U concentration. Coals form the Krepoljin, Soko Banja and Sjenica basins have slightly higher U concentrations than the mentioned group. The highest concentration of U is characteristic for the coal from the Bogovina East field. Concentration of Th in coals from Serbia and Montenegro has proved to be low. Out of all investigated coal basins, only the coal from the Krepoljin and Kolubara basins has high concentration of Th. The hydrothermally altered rocks of the Timok dacite-andesite complex, representing the basement of the Bogovina basin, could be a potential source of U, especially at the bottom part of the Lower seam of the Bogovina East field. CONCLUSIONS: This study shows that brown coals in Serbia and Montenegro (soft to hard brown coals or lignite to sub-bituminous) contain low levels of U (5.30 mg/kg, average value and 2.10 mg/kg geometric mean value) and Th (1.80 mg/kg, average value and 1.12 mg/kg geometric mean value). There are some obvious differences in concentration of U and Th in coals from different basins in Serbia and Montenegro. The approximate value for U and Th release mainly from power plants was 644.33 t and 983.46 t, respectively within the period 1965-2000 for the studied mines in Serbia, and 23.76 t and 15.05 t for the Potrlica mine (Montenegro) within the period 1965-1997. RECOMMENDATIONS: The coals in Serbia and Montenegro show no identifiable unfavourable impact on the surrounding environment, due to low natural radioactive concentration of U and Th, but further investigations concerning human health should be performed. PERSPECTIVES: Preliminary research revealed that in some Serbian coals (and, particularly, parts of the coal seam) U and Th content are rather high. Such coals should be carefully studied, as well as U and Th concentrations in ash, fly ash, waste disposals, nearby soil and ground water. Further studies should include determination of the radioactivity of all these products, and estimation of possible health impact.     

SUSTAINABILITY AT THE LOCAL LEVEL: MANAGEMENT TOOLS AND MUNICIPAL TAX INCENTIVE MODEL

The implementation of sustainable development may seem a simple concept when written on paper. However to carry-out long term actions put forward by the Agenda 21 (AG21) at the local level represents one of the main challenges as municipal governments in general do not have the capacity to effectively implement the process. Regional environmental assessment (REA) has shown to be effective in supporting decision-making not only to correct environmental problems due to past unsustainable social-economic developments but also help local governments to implement sustainable actions. However this requires long-term investments of AG21 plans and projects. The allocation of regular and consistent financial resources is one of the main ingredients for the sustainable development process. But traditional plans and projects financed by national and/or international funds may not be sustainable in the long-term because they become dependent on external funding. Research demonstrate that innovative economic instruments such as ecotaxes represent a feasible alternative to sponsor local sustainability because taxes are collected permanently by the government and could be invested in continuous actions. Ecotaxes experiences have provided important reference to structure a municipal incentive model (MIM) to sponsor AG21’s environmental plans and projects on a long-term (permanent) basis. However sustainable development cannot be solely through economic investments. A comprehensive municipal environmental management scheme (MEMS) has been established to support the incentive model. The scheme seeks not only to improve local institutional framework but also incentive continuous participation of local stakeholders at all levels of society. Participatory events and the provision of incentives (educational and financial) are key to motivate society to protect the environment and support actively the sustainable development process as emphasised in the RIO-92 Conference.     

The importance of free amino acids to the energy metabolism of eggs and larvae of turbot (Scophthalmus maximus)

A study was undertaken to establish the role of free amino acids (FAA) in aerobic energy dissipation in embryos of turbot (Scophthalmus maximus) which contain an oil globule in the egg. Laboratory-reared developing eggs and larvae (15°C, 34 salinity) were measured for oxygen uptake, ammonia excretion, contents of FAA, protein, and ammonium, and volumes of yolksac and oil globule. Newly spawned eggs from different batches contained 55 to 90 nmol egg^–1 of FAA. Resorption of FAA occurred in parallel with the consumption of yolk. Resorption of the oil globule, however, occurred predominantly after hatching and mainly after yolk resorption. The combined data suggest that approximately 70% of the FAA are utilized as an energy substrate, while the rest are polymerized into body proteins. FAA become a significant energy substrate in the early egg stage and account for 100% of the aerobic energy dissipation 2 d after Fertilization then decrease to ca. 60% at the time of hatching. Lipids derived from the oil globule seem to be the main fuel after hatching and account for ca. 90% of the energy dissipation at the onset of first-feeding. Thus, the energetics of fish embryos which contain an oil globule seems to be different from those that depend exclusively on the nutritional reserves of the yolk.     

The effect of nitrogen deficiency,methionine and inhibitors of methionine metabolism on the DMSP contents of Tetraselmis subcordiformis (Stein)

The unicellular alga Tetraselmis (Platymonas) subcordiformis (Prasinophyceae) displayed a two-phase increase in DMSP (dimethylsulfoniopropionate) contents in response to nitrogen deficiency. In the first phase, DMSP pools increased by 75% within 24 h. The second increase in DMSP was observed after 14 d and was accompanied by cyst formation. Methionine metabolism was involved in DMSP accumulation. A 2.6-fold increase of the DMSP pool could be induced by supplementing a complete ASP (artifical seawater Provasoli) medium with 100 M L-methionine. Inhibition of methionine utilization by T. subcordiformis caused by the addition of S-adenosylhomocystein, a competitive inhibitor of S-adenosylmethionine-dependent transmethylases, resulted in a 24% increase of DMSP contents after 7 h. DMSP accumulation after hyperosmotic shock was significantly delayed when methionine liberation from proteins was inhibited by a set of protease inhibitors. A model for the mechanism of DMSP accumulation is presented on the basis of these data and additional information from the literature. It is proposed that methionine availability in T. subcordiformis determines the rate of DMSP synthesis.     

Orientation ofRhizophagus grandis (Coleoptera: Rhizophagidae) to oxygenated monoterpenes in a species-specific predator-prey relationship

Summary The predator,Rhizophagus grandis, is linked to its specific prey,Dendroctonus micans, by semiochemical signals regulating oviposition and long range orientation. A mixture of simple oxygenated monoterpenes [(–)—fenchone, (–)—pinocamphone, rac. camphor, terpinene-4-ol, borneol, fenchol and verbenone], identified from the frass ofD. micans has been found to be extremely active in a flight windtunnel as a long—range attractant for the predator. The mixture elicited 84 % of the response to larval frass of the prey. Excluding pinocamphone from the mixture did not influence its activity. Also, changing the absolute configurations of some of the components (fenchol, terpinene-4-ol and borneol) did not influence the predators' response. However, the addition of (–)—-terpineol increased the attractivity of the synthetic blend to almost that of larval frass of the prey. Ecological implications of the identified semiochemicals and their use in pest management are discussed.     

Utilization of a fumigated sediment by two benthic deposit-feeders:Abra alba (Mollusca: Bivalvia) andEupolymnia nebulosa (Annelida: Polychaeta)

The present study tested the utilization of dead microbial biomass by two benthic deposit-feeders:Abra alba (Wood) (Mollusca: Bivalvia) andEupolymnia nebulosa (Montagu) (Annelida: Polychaeta). Clams were collected in the Canet lagoon during spring 1989. Worms were collected in the Port-Vendres harbour during spring 1989. The¹⁴C-labelled (glutamic acid, 24 h) sediment used during the study was sterilized with 1% chloroform, washed with sterile seawater, and dried (60°C; 48 h). This sterilisation procedure, called fumigation is the least harmful to the sediment (Novitsky 1986). Both clams and worms were incubated in the presence of the fumigated sediment for 5, 10, 20, and 50 h. At the end of each experiment we recorded the radioactivity in four compartments: (1) sediment, (2) dissolved organic matter (DOM), (3) CO₂, and (4) animals. The radioactivity of the sediment was subdivided into five fractions: (i) soluble in 2N HCl, (ii) soluble in hot 5% trichloroacetic acid (TCA), (iii) soluble in 1N NaOH, (iv) soluble in hot 6N HCl, (v) residual (after combustion in a Leco carbon analyser). In the first set of experiments, after 20 h of incubation, 5.4 and 4.7% of the total radioactivity was taken up by clams and worms, respectively. However, a model revealed that this uptake could have been correlated with the release of radiolabelled DOM (33% of total radioactivity during the first 5 h). In order to test this assumption, we used the same protocol with three additional washes of the fumigated sediment. This resulted in a significantly lower uptake by the clams (1.9% of the total radioactivity byt = 50 h), whereas the worms exhibited an uptake similar to that in the initial experiment (5.1% of total radioactivity byt = 50 h). These results underline the importance of considering interactions with DOM when applying radiotracer techniques to the study of benthic food chains. The average ingestion rates of fumigated sediment byA. alba andE. nebulosa were 5.2 10^–2 mg sediment dry wt mg^–1 clam h^–1 and 3.5 10^–2 mg sediment dry wt mg^–1 worm h^–1, respectively, which is comparable to previous data reported for other deposit-feeding bivalves and polychaetes feeding on natural sediment or detritus. The low radioactivity recorded for CO₂ together with the similarity of the changes in the partitioning of the radioactivity within the sediment between control experiments and experiments carried out in the presence of clams or worms suggest low assimilation efficiencies. Therefore, the present study supports the fact that dead microbial biomass does not constitute an important food source for benthic deposit-feeders.     

Analysing the sensitivity behaviour of two hydrology models

Recently, the New Morris Method has been presented as an effective sensitivity analysis tool for mathematical models. The New Morris Method estimates the sensitivity of an output parameter to a given set of input parameters (first-order effects) and the extent these parameters interact with each other (second-order effects). This method requires the specification of two parameters (runs and resolution) that control the sampling of the output parameter to determine its sensitivity to various inputs. The criteria for these parameters have been set on the analysis of a well-behaved analytical function (see Cropp and Braddock, Reliab. Eng. Syst. Saf. 78:77–83, 2002), which may not be applicable to other physical models that describe complex processes. This paper will investigate the appropriateness of the criteria from (Cropp and Braddock, 2002) and hence the effectiveness of the New Morris Method to determine the sensitivity behaviour of two hydrologic models: the Soil Erosion and Deposition System and Griffith University Representation of Urban Hydrology. In the first case, this paper will separately analyse the sensitivity of an output parameter on a set of input parameters (first- and second-order effects) for each model and discuss the physical meaning of these sensitivities. This will be followed by an investigation into the sampling criteria by exploring the convergence of the sensitivity behaviour for each model as the sampling of the parameter space is increased. By comparing these trends to the convergence behaviour from Cropp and Braddock (2002), we will determine how well the New Morris Method estimates the sensitivity for each model and whether the sampling criteria are appropriate for these models. It will be shown that the New Morris Method can provide additional insight into the functioning of these models, and that, under a different metric, the sensitivity behaviour of these models does converge confirming the sampling criteria set by Cropp and Braddock.     

Evaluation of a real-time monitoring system for river quality — a trade-off between risk attitudes,costs, and uncertainty

Uncertainty is definitely one of the key topics in environmental assessment and management. Typically, attempts to reduce uncertainty are subject to expenses. But how to compare and trade-off expenses and the reduced uncertainty? They only seldom allow the use of a single unit. Instead, the whole analysis and decision procedure is very subjective. This paper presents one approach to handle such problems, namely the combined use of Bayesian influence diagrams, and probabilistic risk attitude analysis. The approach was used in the evaluation of three alternatives for a real time river water quality forecasting system. A trade-off analysis of risk attitudes, costs and uncertainty indicated the levels of socioeconomic utility required for investments in the respective systems, and accordingly illuminated the impact of the uncertainties involved on inference and decision-making with various risk attitudes and discount rates.     

A historical study of mineral elements in forest plants from South Norway

Herbarium plants were used as a material to study possible long-term changes in mineral elements of forest plants. Plants from South Norway collected in the period 1870 to 1930 were compared to plants collected in 1982. Relative to mineral contents in plants from 1870 to 1930, the 1982 material showed elevated levels of Zn, Cd, Rb, K, Mn and Ti and decreased levels of Sr, B, Ca and Mo in some of the plant species analysed. Most of these differences may be explained by changes in the environmental conditions, due to differences in chemical composition of precipitation, accelerated soil acidification and subsequent increasing mineral weathering. Consequently analysis of herbarium plants seems to provide valuable information about preindustrial levels of mineral elements and seems to detect changes in mineral elements brought about by recent anthropogenic activity.     

Development of an ombrotrophic peat bog (low ash) reference material for the determination of elemental concentrations

Given the increasing interest in using peat bogs as archives of atmospheric metal deposition, the lack of validated sample preparation methods and suitable certified reference materials has hindered not only the quality assurance of the generated analytical data but also the interpretation and comparison of peat core metal profiles from different laboratories in the international community. Reference materials play an important role in the evaluation of the accuracy of analytical results and are essential parts of good laboratory practice. An ombrotrophic peat bog reference material has been developed by 14 laboratories from nine countries in an inter-laboratory comparison between February and October 2002. The material has been characterised for both acid-extractable and total concentrations of a range of elements, including Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Na, Ni, P, Pb, Ti, V and Zn. The steps involved in the production of the reference material (i.e. collection and preparation, homogeneity and stability studies, and certification) are described in detail.