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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Water pollution control with toxicant avoidance tests

Hadjinicolaou, John. January 1983 (has links)
No description available.
2

Water pollution control with toxicant avoidance tests

Hadjinicolaou, John. January 1983 (has links)
An extensive review of all the avoidance apparatus which have been used to date in chemical avoidance tests and also an analysis of the trends and needs for new improved designs led to the design of a new avoidance apparatus. The new apparatus is a viable tool for analyzing the behavioral responses of fish to potentially toxic effluents in three dimensions. The method is quick, sensitive and relatively easy to use if sufficient fish stock is available. / The variable parameters of the avoidance reaction were three: (a) the type of the pollutant, (b) the injection system, and (c) the concentration of the pollutant. / Statistical analysis for the experiments included preliminary calculations, time series analysis, analysis of variance and Duncan's tests. / Preliminary tests evaluated the general disposition of fish in the channel, the influence of a water acclimation jet and also the effects of noise, light and temperature. Experiments were performed to define the optimal number of fish per experiment, the influence of video analysis and also of variability, adaptability and continuity. / The types of pollutants used were D.S.S. (dodecyl sodium sulfate)--a well-known reference pollutant, polymers, monomers, a plating industrial effluent and its components (Cr, Ni, Fe). / For all of these, horizontal and vertical distributions were produced together with avoidance curves and avoidance reaction representations. / The role of the avoidance reaction in relation to lethal and sublethal levels has been defined; after the evaluation of synergism and antagonism phenomena, proposed adjustments for safe toxicant levels have been estimated.
3

The use of indigenous macroinvertebrates and Daphnia pulex in acute toxicity testing

Everitt, Victoria Jane January 2000 (has links)
Aquatic toxicology has been identified as a valuable tool in the identification and management of chemical pollution in aquatic ecosystems. Standardised methodologies for acute aquatic bioassays have been adopted from international agencies. As a result of these standard methods, the use of laboratory cultured organisms for toxicity testing has been more popular than that of indigenous field-caught organisms. Included in these adopted methods are those for the cultured crustacean Daphnia pUlex. D.pulex is adapted to living in standing water and the suitability of this species to determine toxic effects for South African riverine environments, which are largely flowing, has been questioned. Thus this thesis is a case-study ofthe use of D.pulex and indigenous site-specific macroinvertebrates as toxicity test organisms for setting acute water quality guidelines to protect aquatic ecosystems. The study highlights site-specific problems such as reference sites and organism identification. The acute tolerance of selected indigenous invertebrates was compared to that of D. pulex, using both a single-substance reference toxicant (zinc) and selected whole efiluents. The significance of source population and culture age as a potential source of biological variability between D.pulex cultures was also investigated. D.pulex cultures have been initiated in South Africa from females collected from a number of different local populations; also it is assumed that no genetic change (due to mutation) occurs within a D.pulex culture over time. In order to establish if source population and culture age are a source of biological variability between D.pulex experiments, the acute tolerJuce to zinc of two different D.pulex populations and three different generations within a population were compared. Due to experimental variability results were inconclusive, and differences in tolerance as a result of population difference or culture age could not be determined with confidence. The acute tolerance of D.pulex to a single reference chemical (zinc) and selected whole efiluents was compared to that of selected indigenous invertebrates. Acute 48 h D.pulex zinc tolerance (LC50 range: 0.22 - 0.60 mg/l Zn) was found to be more sensitive than acute 96 h tolerances shown by mayfly species A.fconurus peringueyi (Heptageniidae) (LC50: 17.42 mg/l Zn), Euthrauluselegans (Leptophlebiidae) (LC50: 0.98 mg/IZn), Ba~tidae (LC50: 0.94mg/IZn) and shrimp, Caradina nilotica (Atyidae) (LC50: 3.17 mg/l Zn). This result suggests that guidelines for zinc set using D.pulex will protect the selected indigenous invertebrates. Selected whole eftluents were not acutely toxic to either D.pulex or selected indigenous invertebrates. These experiments were used as a case study for method development regarding the comparative use of D.pulex and indigenous invertebrates in acute whole eftluent toxicity testing. Finally, it is recommended that a suite of indigenous organisms (e.g. macroinvertebrates, fish and algae), as well as laboratory cultured D.pulex, be used in the initial setting of guidelines and that D.pulex be used for routine compliance monitoring. It is futher recommended that a suite of available monitoring methods, such as chemical and biomonitoring methodologies, be used in conjuction with toxicity testing in water quality management.
4

The use of chemical analyses, bioassays and benthic biomonitoring in the toxicity assessment of complex industrial effluents /

Sarakinos, Helen C. January 1997 (has links)
This research examined the toxicity of complex industrial effluents as measured by chemical analyses, whole effluent toxicity (WET) tests and surveys of the receiving water biota. Toxicity of final effluents from 45 diverse facilities was examined to determine whether inferred toxicity based on presence and concentration of priority substances could predict WET, calculated from a battery of bioassays on bacteria, cladocerans and algae. Following corrections of inferred toxicity for particle-bound contaminants and adjustment for free ion activity, correlation between inferred and whole effluent toxicity was highly significant. Effluents with elevated metal concentrations exhibited lower WET than predicted, likely due to negative interactions among trace metals; kraft mill effluents exhibited higher WET than predicted which is consistent with findings in the literature. / The ability of laboratory WET tests to predict thresholds of invertebrate community response to a complex industrial effluent was examined. Patterns in invertebrate community structure were detrended for environmental factors and compared to measured instream effluent concentrations. Laboratory effect thresholds, reported as Maximum Allowable Toxicant Concentrations (MATC), were calculated from a battery of toxicity tests on bacteria, algae, cladocerans and fish. Declines in taxonomic richness corresponded to calculated lab thresholds, while changes in abundance of total taxa and sensitive taxa, (Ephemeroptera, Plecoptera, Trichoptera) occurred at lower concentrations than predicted from MATCs. The tendency for invertebrate abundance to decline at lower instream effluent concentrations than richness supports findings in the literature. Lack of correspondence between lab and field thresholds may be ameliorated by the addition of behavior endpoints, (e.g. avoidance) to toxicity tests.
5

Oxidative stress responses in the aquatic macrophyte, Ceratophyllum Demersum L., as biomarkers of metal exposure

Arnolds, Judith Lize January 2017 (has links)
Thesis (DTech (Environmental Health))--Cape Peninsula University of Technology, 2017. / Metal pollution in aquatic environments is considered a major environmental concern because of variation in several abiotic factors that impose severe restrictions on organisms living in these areas. Ceratophyllum demersum L. (family Ceratophyllaceae), a hornwort or coontail, free floating rootless macrophyte has been suggested a suitable model for investigating metal stress and was used in the current study. This study assessed the use of selected biological responses, namely antioxidant responses and changes in chlorophyll concentration in Ceratophyllum demersum L., as biomarkers of metal exposure, and also investigated the field application of these responses in the Diep River. The ultimate aim was also to determine the usefulness of C. demersum as model of metal contamination and as phytoremediator after a pollution event. An investigation of metal bioaccumulation in this macrophyte exposed to different concentrations of a combination of metals over a five-week exposure period in a greenhouse, was undertaken, as well as a field study in the Diep River, Milnerton, Cape Town and a pond (reference site) at the Cape Peninsula University of Technology, Cape Town, to validate experimental results. In the laboratory study the water was contaminated once off at the beginning of the study, to simulate a pollution event. The metal concentrations in the water and plants were measured in the four treatments and the control every week over a five-week exposure period. The samples were acid-digested and analysed with an Inductively-Coupled Plasma-Mass Spectrophotometer (ICP-MS). The results showed that concentrations of the metals in the water varied in all treatments over time with no specific patterns amongst the treatment groups. This macrophyte proved highly effective in the bioaccumulation of these metals at all four exposure concentrations. The metals bioaccumulated rapidly in the plants after the water was spiked. The main focus of the study was to investigate the possible use of biochemical responses in C. demersum as possible biomarkers for metal exposure. A range of antioxidant/oxidative stress parameters were measured in the plant exposed to a combination of metals (Al, Cu, Fe, Zn) in four different treatments over the five week exposure period. Total antioxidant capacity (TAC) was measured using Total Polyphenols (TP), Ferric Reducing Antioxidant Power (FRAP) and Oxygen Radical Absorbance Capacity assay (ORAC), enzyme activity was determined using Catalase (CAT), Superoxide Dismutase (SOD), Ascorbate Acid (AsA) and Total Glutathione (GSHt) and lipid peroxidation was measured by using Thiobarbituric Acid Reactive Substances (TBARS) and Conjugated Dienes (CDs). The cocktail of the four metals induced significant changes in the antioxidant defence system of C. demersum, including the antioxidant enzyme activities. The different metal exposures disturbed the cellular redox status in the plant. The current study has demonstrated that this macrophyte shows tolerance to metal-induced oxidative stress and that it can survive under relatively high concentrations of these metals by adapting its antioxidant defence strategies. Chlorophyll was extracted in 80% chilled acetone in the dark and the absorbance values were determined using a spectrophotometer. Chlorophyll a (chl a), chlorophyll b (chl b) and total chlorophyll (chl t) contents were measured under different exposure concentrations of metals in the macrophyte. The results of this study indicated that chlorophyll contents were variable over the exposure period and no significant differences in chlorophyll concentrations were found between weeks. A field study in the Diep River and the pond located at the CPUT campus (reference site) was conducted to validate experimental results. Plants in a polluted section of the Diep River were shown to bioaccumulate metals to high concentrations. Bioaccumulation of metals in C. demersum might have induced oxidative stress, and other environmental factors such as temperature- and chemical stress might have caused chlorophyll degradation. The chlorophyll concentrations in the plants of the pond (reference site) might also have been affected by temperature and chemical stress of the water. Significantly higher AsA, CAT, ORAC, SOD and TBARS concentrations in the Diep River plants might be an indication that the plants in the river might be well adapted to the constant exposure to metals and that the plants might have developed a tolerance mechanism to cope with oxidative stress compared to those of the pond. The results show that metals are bioaccumulated quickly by C. demersum after the water is contaminated with metals, i.e. after the "pollution event". However, over time, metals are continuously exchanged between the plants and the water, accounting for the fluctuations in metal concentrations observed over time. This study has shown that C. demersum has phytoremediation potential because it was able to remove high concentrations of metals from the contaminated water. Therefore, C. demersum, can be applied as a model for metal contamination and a phytoremediator after a pollution event. The potential to antioxidant responses and chlorophyll content as biomarkers of metal exposure in C. demersum have been demonstrated.
6

Ephippia Production, Activation, and Use of Ex-Ephippio Neonates of Ceriodaphnia Dubia as Toxicity Test Organisms

Poage, Duane W. 08 1900 (has links)
Ceriodaphnia dubia is widely used as a test organism in monitoring water quality. At the present time, cultures must be continuously maintained in the laboratory. In an attempt to avoid continuous culture and maintenance, the hatching of ephippial eggs of C. dubia would provide test organisms when needed. In order to determine the parameters required for maximum hatching, approximately ninety-four thousand ephippia were exposed to a variety of conditions ranging from light and temperature regimes to drying and freezing. A low hatching yield occurred which is believed to be caused by diminished ephippia viability and/or fertility. To evaluate factors influencing the viability and fertility rate, stains of embryos were examined as were male to female ratios and mating experiments.
7

The use of chemical analyses, bioassays and benthic biomonitoring in the toxicity assessment of complex industrial effluents /

Sarakinos, Helen C. January 1997 (has links)
No description available.
8

Detection, discharge and ecological behaviour of genotoxic organic contaminants in the St. Lawrence and Saguenay rivers

White, Paul Andrew January 1995 (has links)
The goal of this thesis was to examine the sources and ecological behaviour of genotoxic organics in the St. Lawrence river system. A rapid and effective version of the SOS Chromotest was developed to accomplish the task of genotoxicity assessment. The method, validated with standard reference materials, is particularly well suited to complex environmental extracts. The endpoint investigated throughout the thesis, SOS genotoxicity, is empirically related to more familiar endpoints such as mutagenicity and carcinogenicity. Analyses of literature data confirmed correlations between SOS genotoxicity and both Ames/Salmonella mutagenicity and animal carcinogenicity. Analyses of industrial and municipal wastewaters revealed that organic and inorganic chemical production facilities, metal refining and founding facilities and petroleum refineries release high potency wastes. Loading values indicate that low potency sources (e.g. municipal wastewater and pulp & paper facilities) often have exceptionally high loadings. A substantial portion (2.3-99.8%) of industrial genotoxins are associated with suspended particulates. Sorption partition efficients (K$ sb{ rm d-genotox}$) indicate that municipal wastewater and pulp & paper facilities release particularly soluble genotoxins. Extracts of suspended particulate matter collected near industrial discharges are direct-acting. Bottom sediment extracts are less potent and usually require S9 metabolic activation. Genotoxicity of both bottom sediment and suspended particulates are empirically related to the genotoxicity of regional industrial emissions. Direct-acting substances in the water column appear to be less stable and may be converted to more stable pro-genotoxic substances present in the bottom sediments. A mass balance of genotoxicity for St. Lawrence surface waters revealed that domestic, rather than industrial sources make the largest contribution to observed genotoxicity. The importance of domestic wastes was confirmed
9

Detection, discharge and ecological behaviour of genotoxic organic contaminants in the St. Lawrence and Saguenay rivers

White, Paul Andrew January 1995 (has links)
No description available.
10

Capillary electrophoresis and related techniques for the analysis of fresh water algal toxins.

John, Wilson. January 1997 (has links)
As cyanobacteria (also known as blue green algae) produce a range of cyclic peptides which are highly toxic, capillary electrophoresis and associated techniques have been investigated to assess their applicability for toxin monitoring in the water bodies of kwaZulu Natal, South Africa. Capillary electrophoresis (CE) is a technique in which charged molecules can be efficiently separated in a buffer solution within a capillary tube under the influence of a strong electric field. Two CE modes, namely capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) were initially evaluated using a laboratory-built CE instrument. The former mode lacked selectivity due to the similar charge to size ratio of the algal toxins. However, with the latter mode, incorporation of a surfactant (sodium dodecyl sulphate) into the buffer, produced sufficient resolution between components. Parameters including surfactant concentration, buffer ionic strength, buffer pH and operating voltage were systematically optimized to separate the four algal toxins under investigation (microcystin YR, microcystin LR, microcystin RR and nodularin). The optimum separation conditions were: 30 mM borax, 9 mM sodium dodecyl sulphate, pH 9.18, 30 kV applied voltage, 10 s hydrodynamic injection, 70 cm x 50 Ilm Ld. bare fused silica capillary (LEFF 40 cm) and UV detection at 238 nm. Under these conditions, typical detection limits were in the low ng/IlL range (14.13 ng/IlL for microcystin LR to 29.85 ng/ILL for nodularin). The MECC method was evaluated in terms of migration time precision, efficiency and resolution, peak area and normalised peak area precision. Standard deviation values for retention times acquired using replicate electrokinetic injections ranged from 0.018 to 0.054 and 0.069 to 0.148 for hydrodynamic injections. Normalised peak area precision for replicate hydrodynamic injections were in the range 84 to 97 % RSD, while improved % RSD values of 11.5 to 18.7 were achieved for electrokinetic injections. Due to poor precision resulting from the lack of automation on the laboratory built CE system, poor correlation between increasing concentration and a corresponding change in normalised peak areas were achieved. The MECC method developed was applied to the analysis of an algal scum extract to illustrate the technique. A general problem with CE is that it suffers from poor detection sensitivity. Hence in this study, alternative injection modes, sample concentration strategies and alternative detection techniques were investigated in an attempt to improve detection limits for algal toxins. Using optimized electrokinetic injection conditions, detection limits were five to ten times better than those obtained with hydrodynamic injections. On-line sample concentration methods were partially successful. Field amplified back and forth MECC in which analyte injected in the entire column volume and subsequently focused in a narrow band by manipulating the electric field, resulted in an enormous sensitivity enhancement that ranged from 197 times for microcystin RR to 777 times for microcystin YR when compared to hydrodynamic injections. Field amplified sample stacking (FASI) was ineffective for toxin preconcentration, while electro-extraction produced detection limits ranging from 0.27 ng/J.tL for microcystin YR to 1.08 ng/J.tL for microcystin RR. Solid phase extraction, in which analytes are first trapped and concentrated on HPLC material in a cartridge and then eluted in a more concentrated form for injection, was found to be practical only in the offline mode. A concentration detection limit of less than 0.002 ng/J.tL was obtained. Attempts with on-line solid phase extraction failed due to problems associated with coupling the cartridge with the separation capillary. Finally, laser induced fluorescence (LIF) detection was investigated as an alternative to UV detection. Unfortunately, the algal toxins were not amenable to LIF detection because tagging with the fluorescent moiety, fluorescein isothiocyanate (FITC), was prevented by the stereochemistry of these cyclic peptides. A comparative study between HPLC and MECC revealed that the former displayed poor efficiency peaks and long analysis times for toxin analysis. However HPLC was superior in terms of retention time precision (0.12 to 0.64 % RSD) and area precision (1.78 to 2.86 % RSD). Mass detection limits for MECC (0.0142 to 0.0603 ng) were far superior to those achieved by HPLC (0.55 to 1.025 ng). In addition to HPLC and MECC, a preliminary investigation of micro-high performance liquid chromatography (J.tHPLC) and capillary electrochromatography (CEC) for the analysis of algal toxins was made using 50 J.tm Ld. capillary columns packed in-house, with reverse phase HPLC packing material. / Thesis (M.Sc.)-University of Natal, 1997.

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