Critical loads have been used to develop international agreements on acidifying air pollution abatement, and within the UK and other countries, to develop national policies for pollution abatement. The Environment Agency (England and Wales) has regulatory obligations to protect sites of high conservation value from the threat of acidification, and hence requires a practical methodology for acidification assessments at the site-specific scale. The Environment Agency has therefore posed the question: Are the national critical load exceedance models sufficiently robust to form the basis for methods to assess harm to individual sites or are they only useful for national policy development? In order to provide one measure of the appropriateness of applying the models at the site-specific scale we incorporated estimates of uncertainty in both national and site-specific data into the calculation of critical load exceedance for individual sites. The exceedance calculations use data from a wide range of sources and the accuracy of the exceedance will be influenced by the accuracy of the input data sets. Using Monte Carlo methods to incorporate the uncertainty in the input data sets into the calculation a distribution of critical load exceedance values is generated rather than a single point estimate. This paper compares uncertainty analyses for coniferous forested sites in England and Wales using both national scale and site-specific data sets and uncertainty ranges.

Masu salmon Oncorhynchus masou masou divides into two life histories after a year of life in the river, the sea-run form and the fluvial form. Since salmons are anadromous, the sea-run form salmons are known to pollute the river sediments during spawning migration. In this study, we have studied the accumulation of organochlorines in the fluvial form as well as the sea-run form, and discussed their differences. In order to elucidate the accumulation patterns of organochlorines in both the fluvial and sea-run form masu salmons, the concentrations of organochlorines were determined in the muscle of both life histories. The organochlorines in the sea-run form were 7 to 21 times higher than those of fluvial form. Since salmons are semelparous, the carcasses of polluted sea-run form pollute the river sediments. The trans-nonachlor/trans-chlordane (N/C) ratio in the fluvial form (1.93) was significantly lower than that of sea-run form (23.8). This indicates that the fluvial form is polluted by comparatively newly input chemicals. These results suggest that sea-run form masu salmons have the potential to pollute the river sediments secondarily as vectors, but from the difference in N/C ratio between the two forms, the fluvial fish does not seem to be polluted by those organochlorine compounds of sea-run fish origin yet.

Surface water is frequently contaminated by the trace metals, in particular lead and zinc, produced by mining activities. The infiltration of this water is likely to pollute surface soils and ground water. The study of the transfer of trace elements, especially lead, under real conditions is difficult to carry out due to the physicochemical and hydrodynamic complexity of real soil (preferential flows, conditions of unsaturation...), of the presence of colloids and of many candidate elements. The objective of the present study was to gain a better understanding of the parameters influencing the migration processes of trace elements in simplified systems; it was based on the study of Pb transfer in laboratory columns filled with soil. The results showed that retention of lead in soil is strongly dependent on feed flow rate, particulate bed tortuosity, bed height, water-soil surface contact and volume of water. Increase in bed height, water-soil surface contact and particulate bed tortuosity leads to higher contact time thus higher lead retention by soil, whereas increase in feed flow rate and volume of water leads to lower contact time thus lower lead retention by soil.

The prevalence and diversity of antibiotic resistant enterococci populations in samples collected four times from urban sewage treatment plant in Tehran, Iran between June 2005 and July 2006 were studied. Filtered samples were grown on mEnterococci medium containing 4 μg/ml vancomycin after which the enterococci isolates were identified to the species level. All strains were then tested for their resistance against nine antibiotics. Of the 131 isolates, 98 (75%) isolates were identified as Enterococcus gallinarum, followed by 24 (18%) and 9 (7%) for E. faecium and E. casseliflavus, respectively. All E. gallinarum isolates carried vanC1 gene with 64 (65%) and 14 (14%) isolates concomitantly harboured either vanA or vanB gene, respectively. Some E. casseliflavus concomitantly harboured vanA and vanC2 or vanB and vanC2. Typing the total enterococci isolates with a high resolution biochemical fingerprinting method showed a high diversity (D i = 0.91). We have shown by biochemical fingerprinting the presence of highly diverse glycopeptide resistant E. gallinarum and E. casseliflavus that have captured vanA and vanB genetic determinants under natural conditions. To our knowledge this is the first report in this geographical region showing high frequency antibiotic resistant enterococcal populations in particular E. gallinarum carrying assorted vancomycin resistance genes.

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.

This study conducted a two-stage experiment. The first stage attempted to establish biostable filter beds. Two parameters, total bacterial count (TBC) and non-purgeable dissolved carbon (NPDOC), measured by passing through a 0.2 μm membrane filter, were selected to compare the difference of biostability of a filtration system with recirculation with different O₃-to-NPDOC ratios of filtered water. The excitation emission fluorescence matrix (EEFM) was used as an effective tool for understanding information regarding organic characteristics by comparing source filtered water before and after ozonation and the effluent during biostablizing filter. During the second stage, a biostable filter was used to compare differences in biodegradability of ozonated products sodium oxalate and sodium acetate. Experimental results demonstrate that both parameters, NPDOC removal and TBC, can be utilized to evaluate the biostabilty of a filter bed. With each parameter, a plateau was reached in roughly 20 days. The source water from Chen Ching Lake (CCL) contained a protein-like substance determined by the EEFM. This protein-like substance was also destroyed by O₃/NPDOC = 1.1. Soluble microbial products (SMPs) released from the biostablizing filter into the effluent have two peaks in the EEFM, identified as protein-like and humic-like acid. The NPDOC removal for the biostabilizing filter using O₃/NPDOC = 1.7 was less than that using O₃/NPDOC = 1.1. Bacterial counts in the effluent from the biostabilizing filter using O₃/NPDOC = 1.1 was better than that of O₃/NPDOC = 1.7. This difference can be explained by the high ratio of O₃/NPDOC producing by-products of ozonation that were easily utilized by microorganisms; however, filter bed also released relatively more SMPs owing to increased proliferation of microorganisms attached to glass pellets in the filter. Regarding the differences in decomposition of the by-products of ozonation by the biostable filter, such as sodium oxalate, the NPDOC removal at O₃/NPDOC = 1.1 was better than that at O₃/DOC = 1.7. This phenomenon can be explained as previously mentioned.

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.

A two-year study was carried out in the lower part of the Palmones River to describe the role of a small dam controlling the nutrient fluxes to the estuary. Results showed an important spatial heterogeneity in the nutrient content and water properties of lowland catchment due to the effects of the small dam and the effluents of a sewage treatment work. Taking into account the values of hydraulic retention time, the dam could be considered as an optimally dimensioned pre-dam. Therefore, it removed on average more than 25% of total phosphorus (TP) while no net removal was obtained for TN during the studied period. Palmones River exported 11.3 TonsP year⁻¹ of TP and 72.1 TonsN year⁻¹ of TN to the estuary showing important seasonal differences. Less than 10% from the total amount of nutrient was exported during low flow conditions, while in four months with important flooding events, the percentage of total nitrogen exported exceeded 64%.

We investigated the relationships between the composition and structure of macroinvertebrate communities and some environmental variables over a year in four basins of the Etueffont landfill leachate (Belfort, France) using co-inertia analysis. Culicidae larvae were the dominant macroinvertebrate group in the studied basins, contributing to 87% of the total zoobenthos density, followed by Corixidae (8.8%), Chironomids (2.5%) and other larvae (each <1%). The lowest density of chironomid larvae was recorded in the first basin which is used as a discharge system for the leachate produced by the landfill. In basin 4, however, the Baetidae, Orthocladiinae (Orthocladius spp., Chaetocladius spp. and Isocladius spp.) and Tanypodinae (Psectrotanypus spp.) developed favoured by low levels in ammonia, COD, BOD, EC, metals and high oxygen concentrations. The co-inertia analysis illustrated both temporal and spatial variabilities in the basins and revealed a strong relationship between environmental conditions and benthic macroinvertebrates assemblages. This ordination technique showed that the chironomid community structure might be used successfully to differentiate between sites with different levels and types of pollution.

Vegetation both physically and biochemically influences denitrification in wetlands. Litter from various plant species supplies various amounts and qualities of organic carbon to denitrifying bacteria, and may thus affect denitrification capacity. We explore whether there is seasonal variation in the denitrification potential in stands of Glyceria maxima, Phragmites australis, Typha latifolia, and Potamogeton pectinatus (the stands differed in terms of which species was predominant). Experiments and measurements investigated whether denitrification potential was related to organic matter and its availability to denitrifying bacteria, suitability for bacterial growth, and amount in the wetland. Availability of organic material, as measured in the slurries, was highest in the G. maxima and P. pectinatus samples, with the highest availability in May and August. However, when the samples were closer to wetland conditions, i.e., intact sediment cores containing litter and organic sediment, the denitrifying capacity was highest in the cores from G. maxima stands, but lowest in P. pectinatus cores. In addition, the denitrification potential of the intact cores was highest in November. Differences in denitrification capacity between the slurries and intact sediment cores, considering the organic material of the plant species and the seasonal pattern, were attributed to differences in the amount of plant litter generated.