The aim of this study is to determine the solubility rate of tantalum contained in pyrochlore, columbite-tantalite and columbite in simulant lung fluid. The International Commission on Radiological Protection (ICRP), in its recommendation for limiting intakes of radionuclide by workers, has consistently recognized that the biological behavior of any specific material after incorporation can significantly diverge from model prevision. Model parameters should be adjusted to adapt the model for each specific substance material in order to estimate the dose due to this element intake. The most recent ICRP publication 66, respiratory tract dosimetry model, point out that information as data like particle size, aerosols solubility and the material chemical compounds are important parameters in the dose coefficients calculation. This paper studies the solubility in Simulant Lung Fluid (SLF) of Ta present in mineral dust particles. For this study 3 minerals were selected: pyrochlore, columbite-tantalite and columbite. Tantalum dissolution in vitro samples were obtained using the Gamble solution and PIXE (Particle Induced X-ray Emission) as analytical technique. In order to characterize the worker exposure to Ta bearing particles, one Brazilian niobium mine was selected. The mineral dust particles were collected using a six-stage cascade impactor and the elemental mass concentrations and the MMAD (Mass Median Aerodynamic Diameter) were determined. Concentrations of radionuclides from natural series of thorium and uranium were also determined. The results show that the workers are exposed to Ta bearing particles in the respirable fraction of aerosols (aerodynamic diameter (d aer) <2.5 μm) during the mineral processing to obtain Fe-Nb alloy. The solubility in Simulant Lung Fluid (SLF) of Ta present in mineral dust particles depends on the mineral characteristics. The solubility half-time varies between 34 and 62 h depending on the associated mineral.

Manganese (Mn) contamination of drinking water may cause aesthetic and human health problems when concentrations exceed 50 and 500 μg l⁻¹, respectively. In the UK, the majority of Mn-related drinking water supply failures originate from unpolluted upland catchments. The source of Mn is therefore soil, but the exact mechanisms by which it is mobilised into surface waters remain unknown. Elevated Mn concentrations in surface waters have been associated with the rewetting of dried upland soils and with conifer afforestation. We investigated these hypotheses in a laboratory experiment involving the drying and rewetting of intact soil cores (1,900 cm³ volume) of horizons of four representative soil type-land use combinations from an upland water supply catchment in southwest Scotland. Although no statistically significant effect of land use or soil type was detected on Mn concentrations in soil water, Mn release occurred from three soil horizons upon rewetting. Soil water Mn concentrations in the moorland histosol H2 (10–30 cm), the histic podzol H and Eh horizons increased from means of 5.8, 6.2 and 0.6 μg l⁻¹ prior to rewetting to maxima of 90, 76 and 174 μg l⁻¹ after rewetting, respectively. The properties of these three horizons indicate that Mn release is favoured from soil horizons containing a mixture of organic and mineral material. Mineral material provides a source of Mn, but relatively high soil organic matter content is required to facilitate mobilisation. The results can be used alongside soil information to identify catchments at risk of elevated Mn concentrations in water supplies.

The use of vegetated wetlands for accelerating pesticide removal from agricultural runoff is gaining acceptance as a best management practice. In this study, the dissipation of five cotton pesticides – endosulfan, chlorpyrifos, aldicarb, prometryn and diuron – was quantified in cotton field runoff water contained in glasshouse columns, under light or dark conditions. Two water samples sourced from large, non-vegetated storage dams were compared with two other water samples obtained from vegetated wetlands receiving runoff from cotton fields. All pesticides studied except chlorpyrifos dissipated significantly faster from the storage dam samples than the vegetated wetland samples. Suggested reasons include a greater number of pesticide-degrading microorganisms in the storage dam waters and/or the presence of more organic matter in the wetland samples, limiting contaminant volatilisation and hydrolysis. Exposure to light significantly reduced the rate of endosulfan removal, whereas light increased the rate of chlorpyrifos removal. Half-lives are presented for each pesticide where appropriate.

Aquatic macrophytes are well known accumulators for heavy metals, the reason why they are used as bioindicators for water quality and in phytoremediaton strategies. This study reports on the elemental concentrations in four free-floating aquatic macrophytes (S. auriculata; P. stratiotes; E. crassipes and E. azurea) growing in two water reservoirs (Santana e Vigário, Rio de Janeiro State, Brazil) of an electric power plant that receive input from the polluted Paraíba do Sul River. Filtered water samples and water suspended solids from these environments were also analysed. Inductively coupled plasma mass spectrometry was used as the principal method, allowing the determination of up to 41 elements, including the rare-earth elements (REEs) and other trace metals not assayed before in these macrophytes. The results show that all elements studied are accumulated by the macrophytes with concentration ratios (CR = [plant]: [water]) varying from about 1,000 to 200,000, based on the dry weight of the plant species. With a few exceptions, highest accumulations were observed in E. crassipes in which CRs increase in the sequence: Cu < Mo < Cr < Pb < Tl < Fe < La < Zn < Ce< Mn. Surprisingly high CRs (e.g. Ce: 74,000) and corresponding mass concentrations were observed for the rare-earth elements (e.g. [summation operator]REE: 112 mg kg-¹), also measured in the water suspended particle fraction. The results show that this fraction acts as an effective sink for trace metals in the aquatic system studied and seems to play also an important role in the transfer of metals from water to the plant species.

Samples of pig slurry, as well as dairy and poultry manures collected in Brittany (western France) were analysed to test the ability of sterol profiles to provide a fingerprint of pig slurry contribution to soil organic matter. The data show that the 5β-stanol, known as coprostanol, is the most abundant sterol present in pig slurry, whereas this compound occurs only in minor amounts in both poultry and dairy manures. Moreover, systematic variations of (campesterol + sitosterol)/cholesterol (i.e., C₂₈₊₂₉/C₂₇) and (coprostanol + epi-coprostanol)/cholesterol (i.e., 5β/C₂₇) ratios allow to discriminate clearly pig slurry from poultry and dairy manures. The robustness of the pig slurry “sterol fingerprint” was tested by analysing the sterol profiles of soil samples from an experimental field that had received a massive pig slurry input between 10 to 14 years ago. The results indicate that the specific sterol profile of pig slurry is conservative once the slurry has been incorporated into the soil. In particular, the diagnostic 5β/C₂₇ ratio proves to be constant with time in soils having received pig slurry application, even 10 years after the end of the application. The “sterol fingerprint” of pig slurry is thus sufficiently distinctive from dairy and poultry manures, and also sufficiently time-resistant, to be of diagnostic value in determining whether a soil sample was once contaminated by pig slurry.

Critical loads have been successfully used within Europe in the development of effects-based policies for pollution abatement, including the Second Sulphur Protocol and the Protocol to abate acidification, eutrophication and ground-level ozone (CLRTAP, 1979). This success has encouraged the UK Environment Agency and Conservation Agencies to use the national critical load maps as a screening tool in assessing the threats from acidification and eutrophication to designated (Natura 2000) sites. The UK maps of critical loads are based on national-scale data sets appropriate for national-scale assessments, and were never intended for use at the site-specific level. Site-based assessments are often targeted at Special Areas of Conservation, a sub-set of the UK Natura 2000 sites. The spatial data available includes the boundaries of the sites but not the location of the designated features. Ancillary data is variable from one site to another; habitat types may be described in detail with cross-reference to classes of the National Vegetation Classification (NVC: Rodwell, 1991 et seq), but information available on soils and geology is generalised and has not been related to the habitats or species being protected. Hence it can be difficult to relate the individual sites to the national maps, even where appropriate to do so. This paper examines the underlying uncertainties in the national critical load maps showing how the maps could give misleading results if used for site-specific assessments. It also includes advice on how to determine when the national data may be appropriate as a policy-tool at the site-level.

Temporal trends of non-sea salt (nss-) sulfate and nitrate were analyzed from nationwide precipitation chemistry measurements provided by the Ministry of the Environment (MOE) for the 1988-2002 fiscal years (April-March). The concentrations and deposition of nss-sulfate were found to be decreasing, and those of nitrate were stable or slightly increasing at most sites. These deposition trends were discussed from the viewpoint of emissions of SO₂ and NOX during the period of interest. Because monitoring techniques have changed in the number of active sites, samplers, and analytical methods during the operation period, the median of all annual depositions measured in Japan in a specific year was selected as the annual representative. The contribution of specific emission sources was also calculated for 1990 on the basis of the nss-sulfate and nitrate deposition in Japan obtained with a model simulation in which the model did not include volcanic emissions from Mt. Oyama, Miyakejima Island, which began to erupt suddenly and violently in 2000. For nss-sulfate, the calculated deposition agrees well with the intensity and trends of the median up to 1999. After 2000, a higher deposition than calculated in the preceding years was evident, which is attributable to the volcanic SO₂ from Mt. Oyama. For nitrate, both the calculated and observed depositions were slightly increasing; however, the calculation was found to exceed the observation.

The objectives of this study are: (1) Evaluate the capacity of Indian mustard (Brassica juncea) for uptake and accumulation of Cs and Sr natural isotopes. (2) Identify foliar structural and other physiological changes (biomass, relative water content etc.) resulted from the accumulation of these two elements. (3) Monitor the Cs and Sr uptake and bioaccumulation process by spectral reflectance. Potted Indian mustard plants were exposed to different concentrations of Cs (50 and 600 ppm) and Sr (50 and 300 ppm) natural isotopes in solution form for 23 days. Bioaccumulation of Cs and Sr were found in the order of leaves > stems > roots for both Cs- and Sr-treated plants. The highest leaf and root Sr accumulations are observed to be 2,708, and 1,194 mg kg⁻¹, respectively; and the highest leaf and root Cs accumulations are 12,251, and 6,794 mg kg⁻¹, respectively. High translocation efficiency for both elements is documented by shoot/root concentration ratios greater than one. Biomass decreases were observed for plants treated with higher concentration of Cs or Sr. Cs accumulation affected the pigment concentration and internal structure of the leaf and the spectral characteristics of plants. Within the applied concentration range, Sr accumulation resulted in no significant changes in relative water content (RWC), leaf structural and spectral characteristics of mustard plants. Cs shoot concentration showed significant negative correlation with relative water content (RWC; r = −0.88*) and normalized difference vegetative index (NDVI) value (r = −0.68*) of plant shoots. The canopy spectral reflectance and NDVI analysis clearly revealed (p < 0.05) the stress caused by Cs accumulation.

The purpose of this study is to evaluate cost-effective reduction strategies for nitrogen oxides (NO x ) in the Asian region. The source-receptor relationships of the Lagrangian “puff” model of long-range transportation, ATMOS-N, were used to calculate the wet/dry deposition of the nitrogen (N) in Asia. Critical loads of N deposition in Asia were calculated from the relationships between the critical load of sulfur (S) and balance of N in and out using the data of S critical load of RAINS-ASIA. The cost functions of N reduction of Asian countries were derived by the regression analysis with the data of cost functions of European countries used in RAINS. In order to assess the environmental impact, the gaps between N deposition and critical load of N were calculated. The emission of NO x was reduced in some cases of this model, and the changes of gaps between N deposition and critical load were observed as well as the changes of the reduction cost. It is shown that a uniform reduction of NO x emissions by countries in Asia is not cost-effective strategy.

The consequences of nitrogen (N) enrichment for terrestrial and freshwater ecosystems are of increasing concern in many areas due to continued or increasing high emission rates of reactive N. Within terrestrial ecosystems various conceptual frameworks and modelling approaches have been developed which have enhanced our understanding of the sequence of changes associated with increased N availability and help us predict their future impacts. Here, some recent findings are described and their implications for these conceptual frameworks and modelling approaches discussed. They are: (a) an early loss of plant species that are characteristic of low N conditions as N availability increases and a loss of species with high N retention efficiencies (so called N 'filters'), (b) suppression of microbial immobilisation of deposited [graphic removed] due to increased [graphic removed] availability in the early stages of N saturation, (c) the early onset of [graphic removed] leaching due to these changes (a and b above) in both plant and microbial functioning, (d) reduced sensitivity of vegetation to N additions in areas with high historical N deposition, (e) delayed changes in soil C:N changes due to increased net primary productivity and reduced decomposition of soil organic matter. Some suggestions of early indicators of N saturation are suggested (occurrence of mosses; [graphic removed] ratio in surface soils) which indicate either a shift in ecosystem function and/or structure.