A three year long study has been carried out of the distribution of zinc, lead and cadmium within the water, sediments and submerged plants of the Derwent Reservoir and its catchment These studies have been extended to include detailed field investigations of the accumulation of heavy metals by Lemanea fluviatilis, an alga common in the R. Derwent Further field and laboratory investigations have been carried out of the tolerance to zinc of Stxgeoclonxum tenue. Elevated concentrations of zinc, lead and cadmium were shown to be present, in the water and sediments of the R. Derwent at its point of entry to the Derwent Reservoir. These metals were derived mainly from Bolts Burn, a polluted tributary. This latter stream was found to receive inputs of heavy metals from clearly defined sources within an active fluorspar mine. Although old mine workings were present within the catchment, these had a relatively small effect on the composition of water in Bolts Burn and the R. Derwent. Detailed investigations of the composition of stream and river water enabled various aspects of the behaviour of different fractions of metals to be described and compared in polluted and non-polluted reaches. The concentrations of zinc, lead and cadmium within the water, sediments and submerged plants of the Derwent Reservoir were found to be high when compared with data from other published studies. The pollution of the reservoir with these metals may therefore be regarded as serious. Surveys of the distribution of heavy metals in the water column were carried out at different stages in the filling cycle of the reservoir. These, together with surveys of the composition of sediments and submerged plants, enabled several of the major factors influencing the distribution of metals within the reservoir to be determined. Studies of the accumulation of heavy metals by 47 populations of Lemanea fluviatilis indicated that the alga is a potentially useful 'monitor' of pollution by zinc, lead and cadmium in flowing waters. Although the enrichment ratios for these metals were not constant over a range of concentrations in the water, clear linear relationships were apparent between the concentrations of each metal in the water and in filaments of Lemanea. Intensive sampling from a single population in the R. Derwent demonstrated that a proportion of the zinc content of filaments was sensitive to short term fluctuations in the zinc content of the surrounding water. The results of a series of transplant experiments are also reported. Stigeoclonium tenue was found to be abundant in several streams carrying relatively high concentrations of zinc in the water A study of populations isolated from 35 reaches demonstrated that material growing in higher concentrations of zinc in the field had an enhanced tolerance to zinc. This tolerance was stable during long term culturing, and appeared to have a genetic basis. Assays of populations from harder waters suggested that high concentrations of calcium acted to reduce the toxicity of zinc in the field. Further studies performed in the laboratory demonstrated that increases in pH and the concentrations of magnesium, calcium and phosphate all acted to reduce the toxicity of zinc to Stigeoclonium tenue. However, the effects of these factors on toxicity were found to differ between a zinc sensitive population and a zinc tolerant population

No description available.

No description available.

No description available.

Published methods for single and sequential extraction, separation and determination of chromium(III) and (VI) in sewage sludge, soil and dried plant material were critically evaluated. The results obtained illustrate the difficulties of speciation analysis in such complex matrices. A method based on single extraction with 0.43 mol L[-1] acetic acid followed by on-line ion chromatography with chemiluminescence detection was found to be simple, sensitive, free of interferences, and more importantly the integrity of the chromium species was maintained. Instrumental parameters affecting the sensitivity of the chemiluminscence signals were optimised using a multivariate optimisation approach. A linear calibration was obtained from 0.01 to 50 mug L[-1]. Limits of detection were found to be 0.002 mug L[-1] for both Cr(III) and Cr(VI). Limits of determination were found to be 0.02 mug L[-1] for both Cr(III) and Cr(VI). The precision, determined using a 10 mug L[-1] solution of Cr(III) and Cr(VI) was 10.6 +/- 0.52mug L[-1] (4.9%) for Cr(III) and 10.1 +/- 0.50 mug L[-1] (4.9%) for Cr(VI) (n=6). Validation of the method was carried out using two water reference materials certified for total chromium content; LGC CRM 6010 49 mug L[-1] +/- 4 mug L[-1] and NIST SRM 1643d 18.53 mug L[-1] +/- 0.20 mug L[-1]. Results obtained showed good agreement with the certified values; 49.21 mug L[-1] +/- 1.81 mug L[-1] and 19.03 mug L[-1] +/- 1.50 mug L[-1] respectively. The developed method was used to study the distribution of Cr(III) and Cr(VI) species in soils. The species extraction procedure was validated using a certified reference material (CRM): BCR CRM 483. The changes in the distribution of both species in soil that had been through similar pre-treatment steps as in the production of reference materials were studied. This investigation showed that contamination or chemical oxidation could alter the chromium species present within a natural sample during production steps such as milling, homogenisation and sieving. As a result the metal speciation in the product is different from that in the starting material. In order to limit the effect of oxidation jet rather than ball milling is recommended.

Studies have indicated the existence of several possible sources of genetic heterogeneity within the sentinel species Lumbricus rubellus that could compromise its suitability for ecotoxicological assessment. The species appears to consist of two genetically divergent cryptic lineages and has been demonstrated to display genetic adaptation towards contaminants within some populations. In order to investigate the cryptic lineages of L rubellus further a combined morphological and DNA barcoding approach was undertaken, with both the mitochondria! COI gene being sequenced and external morphological characters being assessed. Combined barcoding and morphological analysis confirmed the existence of the previously described genetic lineages of L. rubellus and highlighted a potential lineage-specific morphological trait. The effectiveness of this trait in field identification of the two lineages was tested in a blind trial. This indicated that the trait may be particularly effective in successfully identifying the individuals of one of these lineages. The two cryptic lineages were also analysed in a second study featuring cross-amplifying microsatellite loci. Both the sequencing and fragment analysis of these microsatellite loci strongly supported the existence of a high degree of reproductive isolation between the two lineages. Finally microsatellite markers were applied to test the hypothesis of genetic adaptation within L. rubellus populations located along an aerially-deposited nickel contamination gradient. No support was obtained for the existence of genetic adaptation within these populations. This could indicate that the most heavily contaminated sites represent demographic 'sinks' into which individuals immigrate from adjacent less-contaminated regions. The general implications of these studies are that the two lineages of L rubellus should be treated as separate species in future ecotoxicological trials given their high degree of genetic differentiation. An implication of the nickel study is that L. rubellus may display a greater capacity for tolerating toxic metals through phenotypic plasticity than previous studies have indicated.

A risk assessment strategy considering the impact of chemicals on the whole ecosystem has been developed in order to create a sound and useful method for quantifying and comparing global risks posed by the main different hazardous chemicals found in the environment. This index, called the Environmental Risk Index for a Complete Assessment (ERICA), merges in a single number the environmental assessment, the human health risk assessment and the uncertainty caused by missing or unreliable data. ERICA uses a scoring system with parameters for the main characteristics of the pollutants. The main advantage is that it preserves a simple approach by condensing in this single value an analysis of the risk for the area under observation. The availability and reliability of the data is an important part of the work done to build the index. Experimental and predictive data were compared to evaluate the reliability. Data were derived both from literature sources (experimental models mainly) and predictive models. ERICA can be considered a diagnostic and prognostic tool for environmental contaminants in critical and potentially dangerous sites, such as incinerators, landfills and industrial areas or in broader geographical areas. The application of the proposed integrated index provides a preliminary quantitative analysis of possible environmental alerts due to the presence of one or more pollutants in the investigated site. This thesis presents the method and the equations behind the index and a first case study based on the Italian legislation and a pilot study on a location on the Italian seacoast.

No description available.

Track and footpath conditions were investigated on the Aberffraw sand dunes, Anglesey. Soil bulk density and penetration resistance were related to the number of passages by cars or walkers and was increased on tracks and footpaths; compaction was examined to 50 cm depth. Trampling increased soil moisture in dry areas and compaction per se as probably beneficial to plants. Vegetation was shown by multivariate analysis to be related to the soil parameters. Light trampling favoured dicotyledonous species but they were later eliminated and monooctiledonous species survived with a reduction in biomass and species number. Track OccAxee.c*es. prefers-n-0-e indices were calculated for the common species and survival strategies considered; tillering capacity may be more important than protected meristems. Trampling and wear by vehicles was applied to undamaged vegetation and the effect measured before and after recovery. Intensity was found to be more important than the effect of frequency. 1820 walkers or 20Q vehicles reduced cover to 50,'; in the summer; vehicles were more destructive in winter. Physical carrying capacity was calculated and relative vulnerability of various habitats was estimated from data of other workers. Soils were found to decompress when traffic was removed but vegetation initially inhibited the process. Tillage, seeding and the effects of fertiliser on vegetation regeneration were studied; the first inhibiting and the latter two treatments accelerating the process. Turves in greenhol.se conditions were used to predict the results. The desirable end point was considered from the management point of view. The effect of a track on the microclimate was studied with emphasis on thermal Characteristics: vegetation removal had a greater effect than soil compaction. The effect on plants in relation to their distribution and morphology was discussed. Models describing the ecological changes caused by trampling and the physical carrying capacity of sand dune pasture were constructed.

The biodegradation of urea by phototrophic and heterotrophic micro organisms and the urea sea water concentration were investigated in relation to the microbial population, inorganic sources of nitrogen and the hydrography of the Elbe estuary and Southern German Bight during three cruises (HGL Cruises) from the end of July to the end of September 1976. During the HGL cruises and a preliminary investigation in Beaumaris Bay and the Menai Strait, no evidence was found to suggest that land derived urea was an important contributor to sea water urea concentration. In situ production seems likely to be a major source of urea. Urea contributes an ecologically significant amount to the ttotal nitrogen' (ammonium, nitrate, nitrite and urea-N) in the Elbe estuary and S. German Bight. Urea-N concentrations in the latter water, although showing greater spacial variation than the inorganic nitrogen, often exceeded the concentrations of the inorganic nitrogen. Urea concentrations were highest during periods of greatest biological activity (Cruise HGL I:July-August) and decreased as the year advanced. Both phototrophic and heterotrophic micro organisms are important in the biodegradation of urea and rates of degradation were highest during the time of highest biological activity (Cruise HGL I: July-August), phototrophic urea degradation predominating in the Elbe estuary while heterotrophic degradation generally predominated in offshore waters. A complex relationship may exist between the urea producers (possibly zooplankton) and urea degraders as well as between the phototrophic and heterotrophic micro organisms. Distinct water regimes (the Elbe, Coastal and North Sea regimes) of different physical characteristics, often separated by frontal regions were encountered on the HGL cruises. The distribution of the micro organisms and sea water urea concentrations were related to the hydrography and these in turn affected the distribution of rates of urea biodegradation. Urea assimilation indices indicated that in the stratified North Sea regime, containing low inorganic nitrogen, bacteria were more effective urea degraders than phytoplankton. Cellular ATP: cellular C ratios may be a useful indicator of physiological activity and environmental stress. Urea assimilation indices and cellular ATP: cellular C ratios may indicate that the micro organisms in the Elbe estuary are under greater environmental stress than those in the more offshore waters of the North sea regime.