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No description available.

Chapter one summarises the development of UK legislation for the protection of the aquatic environment, and highlights current EC legislative requirements for water quality. The need for on-line water quality monitoring and the alternative instrumental approaches to it are discussed, together with the philosophy of "easy care instrumentation" and water industry requirements for online analysers. A simple spectrophotometric FI system is proposed for the on-line determination of a range of water quality parameters. The following chapter details instrumentation used in the FI system, emphasising the solid-state photometric detector. Development of an FI manifold for the determination of aluminium in potable and treated waters is covered in the next chapter. The method, based on complexation of aluminium with pyrocatechol violet is compared with a standard Driscoll procedure. Details of the construction and testing of a fully automated FI instrument are also given. Chapter four describes the development of a modular automated FI monitor with a PC compatible STEbus based computer system. Successful operation of this monitor is illustrated by its application to the determination of residual coagulants (aluminium and iron). Full details of software routines for control, processing and validation are given together with results from a tap water trial for dissolved aluminium. The FI determination of residual iron by its complexation with ferene S, and the application of the optimised method in the STEbus based monitor is detailed in chapter five. In the final chapter the use of on-line FI oxidation procedures for the determination of dissolved organic carbon are examined. The oxidation of a wide range of organic species to carbon dioxide using a silver catalysed persulphate reaction, enhanced with UV irradiation and a stopped-flow procedure is described. The sequential determination of inorganic and organic carbon without separation of the fractions is also investigated.

Thesis (M. Sc.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 98-101).

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The operation and maintenance of highways contributes a variety of pollutants to surface and subsurface waters. Solids, heavy metals, nutrients, oil and grease, pesticides and bacteria can all be associated with highway runoff. Although the full extent of the effect of all these runoff constituents upon the quality of surrounding waters is not well defined, this study will mainly concentrate on nutrient contaminants (essentially phosphorus). The last decade has seen increasing efforts in research and development to abate contaminant discharges from highway runoff using a number of treatment facilities such as swale and detention/retention ponds. An evaluation of the effectiveness of these systems in removing phosphorus by physical, chemical and biological uptake is the aim of this research endeavor. This study represent the first step towards the determination of design criteria for swales and detention/retention ponds based on water quality improvement.

Zebra mussels (Dreissena polymorpha) have invaded a great proportion of the waters of the eastern part of North America. This mollusk may be a useful sentinel species for bioaccumulation of heavy metals and organic contaminants in aquatic ecosystems. The zebra mussel's capacity to bioaccumulate cadmium at environmentally relevant exposure and to sequester metals in metal-binding proteins, metallothioneins, was investigated. Elevated (relative to control) concentrations of Cd$ sp{2+}$ were detected in Dreissena exposed to $ ge$2 $ mu$g Cd/liter suggesting that zebra mussels cannot regulate Cd$ sp{2+}$ of trace exposure concentration. More than 85% of the measured Cd$ sp{2+}$ was bound to metallothioneins. / Lesser scaup (Aythya affinis) was assessed as a model species for potential impacts of zebra mussels on higher trophic levels. The feasibility of incubating and rearing scaup in semi-natural conditions was evaluated. A series of biomarkers was assessed in 3 groups of scaup fed a contaminant-free diet or diets containing zebra mussels from the St-Lawrence River or Lake Erie. / Lesser scaup proved to be a suitable species to raise in captivity providing daily water misting through out incubation and strict hygiene conditions during brooding. A hatching success of 89% was achieved. Appropriate housing, feeding and bathing conditions yielded low (3%) post-hatching mortality. / Phagocytosis and respiratory burst activities of heterophils of scaup were suppressed after 6 weeks of feeding on zebra mussels, compared to the control group. These two heterophilic functions were negatively correlated with the incidence of pododermatitis (bacterial feet infection), suggesting a suppression of the non specific immunity. Increased liver/body mass ratio and decreased hepatic vitamin A (retinol and retinyl palmitate) concentrations were observed in scaups fed zebra mussels. Lipid accumulation and glycogen overload were found in the livers of scaups fed mussels from the St-Lawrence River and the Lake Erie groups, respectively. These immunological, biochemical and histopathological biomarkers show promise for monitoring "early" injury and may help in the understanding of health impairment of different species of waterfowl exposed to xenobiotics via contaminated food sources.

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The primary objective of this work was to determine the tissue-specific bioconcentration factors (BCFs) of the selected pharmaceuticals: norethindrone (NET), ibuprofen (IBU), verapamil (VER), clozapine (CLZ) and fenofibrate (FFB) in two freshwater fishes: fathead minnow and channel catfish. BCF tests on fathead followed the standard OECD 42-day test while a 14-day abridged test design was used in catfish exposures. Additional objectives included a) comparing the measured BCFs to the US EPA's BCFWIN model predicted values, b) comparing the BCF results from the standard and reduced tests, and c) prediction of chronic risk of the pharmaceuticals in fish using the human therapeutic plasma concentrations. Each test included uptake and depuration phases to measure tissue-specific kinetic BCFs. The results indicated that all the pharmaceuticals, except IBU, have the potential for accumulation in fish. Estimated BCFs for NET, VER and FFB may not be significant in view of the current regulatory trigger level (BCF ≥ 2000); however, CLZ's BCF in the liver had approached the criterion level. Significant differences were noticed in the tissue-specific uptake levels of the pharmaceuticals with the following general trend: (liver/kidney) > (gill/brain) > (heart/muscle) > plasma. IBU uptake was highest in the plasma. When compared to the measured BCFs, predicted values for NET, IBU, VER and FFB were slightly overestimated but did not differ largely. However, the measured BCF of CLZ in the liver was approximately two-orders of magnitude higher than the predicted level. The tissue-BCFs for the two species were not widely different indicating the potential usefulness of the reduced BCF test. Comparison of fish and human plasma levels indicated that NET, CLZ and VER have the potential to cause chronic effects in fish.

The toxic effects of cadmium on aspects of the survival, behaviour and reproduction of Gammarus pulex and Asellus aquaticus are described in some detail. Some of the laboratory procedures were validated in field experiments. The presence of the parasites Pomphorhynchus laevis and Echinorhynchu_s1truttae does not modify the toxicity of cadmium (0.01-1.0 mgl ) to their intermediate-Fost G. pu7ex. Pretreatment for 24 hours with 0-47 μgl cadmium alters the distribution of separation times when precopula pairs of G. pu7ex are disrupted by the invertebrate anaesthetic 2- phenoxyethanol. Precop1la is directly disrupted by exposure to cadmium (0.1-12.7 mgl )_ýut recovery can follow. Pretreatment with cadmium (3-140 μgl ) for 24 hours, of similarly sizeci male G. pulex and subsequent exposure to 0.13 and 2.23 μgl while in competition for access to a female may increase tolerance and enhance reproductive success, or initiate irreversible toxic effects and impair competitive ability. Exposure of female G. pulex-1to 2.0 and 9.6 μg1 , and female A. aquaticus to 40.2 pgl cadmium pre-fertilization reduces their fecundity. Brood development times of G. pulex and A. aquaticus exposed to 2.1 and 12.4 μg1-1 cadmium postfertilization are extended by 2 and 2.7 days respectively. The embryonic development and abortion during brooding are described in detail for A. aquaticus. An explanation of reduced final brood size in Asel7us is Postulated. Growth of juveniles of both test species exposed during brooding is assessed. Single and repeated 24 hour field simulations of acidic deposition demonstrate increased host sensitivity of G. pulex infected with P. 7aevis. The effects of low pH and elevated aluminium concentrations are mitigated to some extent by liming. Six hour field simulations of the individual components of farm waste demonstrated that infected gammarids were more susceptible under conditions of low dissolved oxygen than uninfected conspecifics.