No description available.

No description available.

No description available.

This thesis explored the uptake into the freshwater shrimp (Gammarus pulex) and the water boatman (Notonecta glauca) of key pharmaceuticals drawn from different therapeutic classes and covering a range of physico-chemical properties. For one compound, uptake was also assessed using the freshwater snail Planobarius corneus. In G. pulex, bioconcentration factors (BCFs) ranged from 4.6 – 185900 and increased in the order moclobemide < 5-fluoruracil < carbamazepine < diazepam < carvedilol < fluoxetine. In N. glauca BCFs ranged from 0.1 – 1.6 and increased in the order 5-fluorouracil < carbamazepine < moclobemide < diazepam < fluoxetine < carvedilol. For P. corneus, the BCF for carvedilol was 57.3. The metabolism of the study pharmaceuticals in the shrimp was investigated. Diazepam was found to be metabolized by G. pulex and a metabolite was detected and tentatively identified as nordiazepam. For the other five study compounds no metabolites were observed and it was inferred that metabolism in G. pulex may not influence the BCF. The influence of dietary uptake was explored in the test organisms with carvedilol and fluoxetine. It was found that uptake from water was the predominant route of exposure for G. pulex but the data for N. glauca was contrasting and the exposure from the food was predominant. In both organisms a combination of food and water exposure resulted in a higher uptake of the compounds. The differences in degree of uptake from water across the organisms may be due to differences in mode of respiration, behaviour and the pH of the test system. The differences in degree of uptake from food across the organisms may be due to differences in feeding strategies. The degree of uptake of pharmaceuticals within an organism was related to the hydrophobicity of the pharmaceuticals.

No description available.

On 26 April 1986, the worst nuclear accident in the history of the nuclear industry occurred at Unit 4 of the Chernobyl nuclear power plant (ChNPP) in the Ukraine (at that time a Republic of the Soviet Union) resulting a large amount of radioactive nuclides released into the environment in Russia, Ukraine, Belarus and other European countries. The chronic radiation doses from radioactive nuclides released from the accident are still significant in the freshwater aquatic environment of the 30 km Exclusion Zone around Chernobyl. In this study, current methods of estimating radiation doses have been further developed by model inter-comparison and testing against empirical data. This research also supports previous work on the effects of radiation on aquatic biota by accurately measuring the external radiation dose in the littoral zone of Svyatoye and Perstok lakes in Belarus. The testing and critical analysis of five dose assessment models (RESRAD, FASSET, ERICA, R&D128 and the D-Max model) was carried out in order to understand the key factors which influence predictions of both internal and external doses. For the internal dose, studies of the relationship between modelled dose and organism mass showed that mass is a more important factor than organism shape. The predictions of external dose were generally more variable than those for internal dose. The most important factor causing variation in external dose was the assumed habitat of the organism and the occupancy factor. The Monte Carlo method was used to estimate the uncertainty in internal dose rate caused by the variability of fish mass and fish concentration in real environments. It was found that the variability in Cs-137 activity concentration in different fish was the most important factor contributing to the uncertainty of predictions of internal dose rate. Organism size at different life stages also has a large influence on dose. For young, small, fish, the internal dose is lower than the range of internal doses estimated by the different models, whilst the external dose could be greater than that estimated by models, especially in cases where part of the life cycle is spent on the sediment surface. Using measured values of tissue activity concentration, the model predictions of doses in Svyatoye and Perstok lakes, show good agreement with each other. In cases when tissue activity concentration data are not available, these have to be estimated from the tissue-water Concentration Ratio (CR). In this case, the predicted internal dose rates (using radionuclide concentration in the water) are more uncertain because of the variation of CR in the models. The model where CR is estimated depending on water chemistry gives the best prediction in this case. Measurements were made of the beta- and gamma- dose rate in three lakes (Perstok, Svyatoye and Dvorishche) giving profiles of dose as a function of depth. The method for gamma dose rate measurement worked well and a simple model for external gamma dose rate with depth above and below the sediment surface was found to give reasonable agreement with measured values. The beta in situ measurement was not successful and the method would need further investigation. The modelling studies carried out showed that internal dose rates to fish in Svyatoye and Perstok lakes are lower than or close to the 40 μGy hr-1 recommended limit for possible impacts from radiation .The external dose rate to insect larvae and benthic fish is much higher than to pelagic fish because the former live in or on the sediment which has a much higher activity concentration than the water. None of the estimated external dose rates in these lakes was higher than 10 μGy hr-1. It is concluded that the external dose rates to benthic biota and large fish in these closed lakes are still significant at this long time after the Chernobyl accident. But, radiation effects on these organisms may not be clearly seen, since the dose rates are below or close to guideline limits.

Amersham plc, now GE Healthcare, has discharged both organically bound tritium (OBT) and tritiated water (HTO) into the Severn estuary since 1981. The OBT component of these discharges results in elevated tritium (3H) activities in the sediments and biota of the estuary. A monthly sampling programme, covering February 2000 to May 2004, has provided the first detailed description of the spatial and temporal distribution of 3H activities in surface sediments from the estuary. Four sediment cores were also collected from salt marshes on the northern shore, to obtain longer term records of tritium accumulation. The spatial distribution of sediment 3H activities correlates well with predicted patterns of suspended sediment circulation, with higher activities (up to 3 Bq/g dry weight) in sediments from sites within 10 km of the Amersham plc discharge point and at a greater distance to the east. Temporal variations in the 3H activities of both surface and core sediments are predominantly controlled by the magnitude, composition and pre-discharge treatment of organic 3H discharges from Amersham plc, with secondary sediment composition effects; lower 3H activities are generally measured in sandy/gravelly sediments than in muddy sediments. The dated sediment 3H activity profile in one of the salt marsh cores corresponds to the Amersham plc OBT discharge record, indicating that 3H is persistent in sediments over a period of 25 years. Up to 60 % of the OBT in sediments could only be extracted with strong acids and bases, indicating that it may be composed of large, complex and hydrophobic compounds that are only extractable when lysed, such as humic compounds and/or large biomolecules. The sediment-bound fraction of OBT is predicted to be less than 2 % of the total organic tritium discharged from Amersham plc, however, these molecules do have the potential to remain in salt marsh and subtidal mud patch sediments for decades, unless the sediments are eroded and resuspended, until tritium activities decline by radioactive decay.

Umsetzung der Europäischen Wasserrahmenrichtlinie (EU-WRRL) für die Qualitätskomponente Fischfauna in Sachsen

Umsetzung der Europäischen Wasserrahmenrichtlinie (EU-WRRL) für die Qualitätskomponente Fischfauna in Sachsen

Umsetzung der Europäischen Wasserrahmenrichtlinie (EU-WRRL) für die Qualitätskomponente Fischfauna in Sachsen