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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

The determination of alkylphenols in natural waters by SPE-HPLC-fluorescence detection

Smith, Eileen Mary January 2001 (has links)
No description available.
2

Studies on the hormonal activity of wastewater during its treatment

Kirk, Lucy Ann January 2002 (has links)
No description available.
3

Sorption and remobilization of organic micropollutants in the aquatic environment

Bowman, Janet Clare January 2002 (has links)
No description available.
4

Multiple hormonal activities of industrial chemicals

Sherazi, Aisha January 2000 (has links)
No description available.
5

Kemikalier på förskolor : En studie om hormonstörande ämnen och medvetenheten hos förskolepersonal

Huuva, Catrin January 2013 (has links)
Chemicals in preschools - a study of endocrine disrupting chemicals and awareness among preschool teachers The purpose of this study was to investigate endocrine disrupting chemicals that have been shown in preschools and also the preschool teachers’ awareness of these chemicals. There were two methods used for completing this study; a literature study and a practical study. The literature study was made by researching on the internet and in books. The practical study was performed by sending questionnaires to all preschools in Kiruna municipality to study awareness among staff. The result shows that there are many different chemicals in preschools and that they were found in beds, floor, toys, food packaging etc. The result also shows that the preschool teachers were somewhat aware of chemicals hidden in products and interior, but needed more knowledge to do something. The response rate of the survey was 89 percent. 25 of 28 preschools participated in the survey. Children were exposed to chemicals from air, dust, food, etc. The chemicals might affect children through a variety of diseases; reproductive problems, diabetes, cancer, allergies, asthma, etc. We need more laws and restrictions to overcome the chemical problem. To solve the problem, knowledge must be given to both preschool staff and parents. Information must be easily accessible. Communities need to be more conscious of chemicals in the preschools and also in the rest of the children's everyday lives.
6

Seasonal effects of treated sewage effluents upon the reproduction and development of European freshwater molluscs

Clarke, Neil January 2009 (has links)
The most widespread evidence of environmental endocrine disruption in aquatic wildlife is from the feminising effects of oestrogenic endocrine disrupting compounds. However, very little is known of the effects of these chemicals (and others) upon freshwater molluscs found in our river and lakes. This thesis aimed at evaluating the effects of treated sewage effluent upon the reproductive and developmental cycle of a range of commonly found European freshwater gastropod molluscs. Initial mesocosm experiments were undertaken to test a range of mollusc species for their the suitability to the experimental system, and to test adult snails for their reproductive and developmental responses during spring to summer time. With suitable species chosen, P.corneus, a pulmonate species (sequential hermaphrodite), and V. Viviparus a prosobranch species (dioeious; separate sexes), full reproductive output was assessed over summertime and into autumn, along with developmental responses amongst the F1 generation of snails. My results suggest that the affects of effluent upon the reproductive and developmental cycle of P. corneus are strongly mitigated by both day length and water temperature (day length is most important with V. viviparus); results are sensitive to seasonal effects. However, at the peak of reproduction mid summer, P. corneus produced significantly more egg masses in effluent (100% effluent particularly), and more than one parameter of reproduction was affected. Egg masses were significantly smaller in effluent and contained significantly fewer eggs per mass. Further, there were indications that total reproductive output was increased (100% effluent significantly) in effluent compared to the river water control. In the prosobranch species V. viviparus results were less convincing, however, in 100% effluent a second reproductive peak occurred that was not seen in river water. Further, in both species there was a failure of certain reproductive parameters to observe the normal seasonal decline towards winter. In P. corneus there was a failure to stop producing egg masses in effluent, in V. viviparus the second reproductive peak in effluent could also threaten their survival with winter approaching. Developmental effects in the F1 generation were the subject of preliminary investigations, however, F1 V. viviparus demonstrated a higher than normal incidence of intersex (male and female developmental features) in effluent, and P. corneus appeared to have disturbed reproductive function (disturbance of both male and female reproductive function in the ovotestis). Therefore, both of these species of molluscs demonstrated that they are sensitive to the effects of effluent in mesocosm studies. However, we need to understand much more about their responses to effluent; in particular whether these effects could have repercussions for wild mollusc populations, and whether these effects could occur over more than one generation of snail threatening the survival of wild populations of molluscs.
7

The impacts of chemical discharges on the reproductive biology of the bullhead Cottus gobio and the dipper Cinclus cinclus in the Tamar catchment

Fowler, Vivienne Frances January 2011 (has links)
It is now well established that a wide range of natural and anthropogenic chemicals present in the aquatic environment have the potential to disrupt the endocrine system of many organisms. In fish, many of these effects appear to be of a feminising nature, including stimulation of vitellogenin production and induction of intersex. In piscivorous birds these so called endocrine disrupting contaminants have been shown to impair reproduction, influencing reproductive behaviour, sex ratio, eggshell thickness and reproductive success. The effects seen in fish have been associated with high levels of oestrogenic activity in the effluent from waste water treatments works (WwTWs), but few studies have focused on the effects of WwTWs effluents on birds. In this thesis, the effects of effluents from WwTWs on fish and birds were investigated in the Tamar catchment, SW England. The work spanned making detailed assessment on the oestrogenic and anti-androgenic activity of 3 WwTWs effluents, using a variety of water sampling techniques and applying both recombinant yeast oestrogen screen (YES) and recombinant yeast androgen screen (anti-YAS) bioassays to quantify the different hormonal activities. A survey was undertaken of the hormonal activities at 13 sites to determine concentrations of contaminants in the surface waters throughout the Tamar catchment, using both recombinant yeast screens and targeted analytical chemistry for specific pollutants (LC/MS-TOF and GCMS). An ELISA was developed to quantify vitellogenin (VTG) in the bullhead (our study fish sentinel) as a biomarker of oestrogen exposure, and evidence of endocrine disruption was investigated in wild populations of the bullhead, Cottus gobio and the dipper, Cinclus cinclus. Macroinvertebrates from upstream and downstream of three WwTW's effluent discharges and from three sampling sites were also sampled as an index of overall water quality in the Tamar catchment, and as an assessment of food availability for the bullheads and dippers. For the studies on the hormonal activities in three WwTWs in the Tamar catchment, samples were collected by both spot and passive sampling; passive samplers (in replicate) were placed in the effluent discharges for a three week period, and collected on days 7, 14 and 21, spot samples were taken simultaneously. Measurement of total oestrogenic and total anti-androgenic activity was conducted using the YES and anti-YAS, respectively. Spot and passive samples were collected from 13 sites within the Tamar catchment (sampling sites were >2 km downstream of effluent discharges). Additionally, liquid chromatography mass spectrometry time-of-flight (LC/MS-TOF) was used to measure the concentration of oestrone (E1), 17β-oestrodiol (E2) and 17α-ethinylestradiol (EE2) in each sample. Gas chromatography mass spectrometry (GCMS) was used to measure the concentration of individual PBDE and PCB congeners in the spot samples only. Levels of oestrogenic and anti-androgenic activity observed in the WwTWs effluent were comparable with those measured in effluents in the UK and in other countries. Surface waters of the Tamar, away from the WwTWs effluent discharges, contained very little oestrogenic activity (<1.1 ng E2 EQs L-1), and anti-androgenic activity was undetectable. Quantification of oestrogenic activity using passive samplers showed an increasing amount of total oestrogenic activity between days 7 and 21 when measured by the both the YES and LC/MS-TOF. Low levels of PBDE congeners 47, 99, 100, 138 and 153 were detected in the spot samples taken from the Tamar catchment, with BDE 47 being the most abundant. In contrast PCBs were undetectable. Neither PBDEs nor PCBs were detected in any of the extracts from the passive samples. No assay was available to measure VTG (one of the most widely used biomarkers of oestrogen exposure in fish) in the bullhead and so an enzyme linked immunosorbant assay (ELISA) was developed for application to studies on wild bullheads in the Tamar catchment. The bullhead vitellogenin (bh-VTG) ELISA was developed successfully, and proved to be sensitive and robust, with a detection range between 10.5 and 300 ng bh-VTG mL-1 (undiluted), comparing favourably with other fish VTG ELISAs. Plasma VTG concentrations measured in male bullheads (collected from the same sites as for the water samples) ranged from below the limit of detection to 990 ng bh-VTG mL-1. Whether these upper levels in the range reflected VTG induction was difficult to conclude. Because of this controlled caged exposures with bullheads and trout were used to assess the relative levels of oestrogenicity in two key WwTWs effluent discharges and to determine the response sensitivity of the bullheads (and trout) to those effluents. These controlled exposures found no responses in plasma VTG in bullheads (ranging between 126 and 934 ng bh-VTG mL-1) suggesting a lack of sensitivity for VTG induction. This was supported by the inability to induce VTG in fish held in the laboratory and treated with steroidal oestrogens. For the effluent exposures on the caged rainbow trout, it was also found that there was no significant induction of VTG, a species normally sensitive to oestrogens. These findings may indicate that the fish were highly stressed due to the river being in spate and the movement of the cages during the controlled exposures. It may also be the case, however, that the use of immature female rainbow trout with a highly variable baseline plasma VTG concentration may prevent any detection of a response. There were no signs of sexual disruption in any of the gonads analysed from either male or female wild bullheads, demonstrating that any hormonal activity present in the catchment away from the WwTWs effluents was not sufficient to induce adverse effects on reproductive development. An interesting feature noted in the male testes of the bullheads was the presence of spermatid masses, which have been recorded in 10 other Cottidae species, but not previously in the bullhead. For the studies on dippers, eggs were collected from the nests of breeding dippers to measure for sperm numbers and morphology from sperm trapped in the perivitelline membrane (PVM), and the yolks were analysed for PBDEs, PCBs and organochlorine pesticides (OCPs) by GCMS, for E1, E2, and EE2 by LC/MS-TOF. Eggs of the dipper were collected from nests at the 13 sampling sites, plus an additional three sites and over three years of field study. The number of sperm trapped in the PVM ranged between three and 188, with a mean of 68.78 ± 8.78 SE. Dipper sperm had not previously been characterised, and was found to be similar to other passerine sperm, in that the head was helical, complemented by a mitochondrial helix or keel, which continued in a spiral around the flagellum. Sperm were classed as ‘abnormal’ if they did not adhere to this typical structure. No assessment of motility could be made in relation to the structural abnormalities seen. Contaminants in the dipper eggs were dominated by BDE 99, an unusual result considering the dippers aquatic lifestyle. PCB 153 was the most common PCB, and p,p’-DDE was the most abundant OCP; all other pesticides tested were below the limit of detection, as were the levels of all three steroid oestrogens. There was inter- and intra-nest variability between contaminant burdens in all eggs as well as the number of sperm trapped in the PVM, but there was no relationship between sperm number and the level of contaminant loadings in the eggs. There were no correlations between contaminants and oestrogenic activity measured in the water samples, and plasma VTG concentrations in bullheads or contaminant loadings in eggs, or indeed sperm number. Analysis of macroinvertebrate assemblages proved that the surface waters of the Tamar catchment were of ‘very good’ quality, even in close proximity to WwTWs effluent discharges.
8

Thyromimetic and Proteomic Analysis of Secondary Wastewater Effluent

Littlehat, Jr., Peter January 2007 (has links)
Wastewater reclamation and reuse is imperative in water-starved areas such as the southwestern United States. In the Tucson Active Management Area, a geographic region defined for the purpose of groundwater management, the total demand for water already exceeds the available water supply, which consists of renewable ground water and the regional entitlement to Central Arizona Project water. Thus, the regional demand cannot be satisfied without resorting to groundwater mining unless water is reclaimed for local beneficial use. Less certain are the acceptable uses for reclaimed water and the nature of use-dependent treatments or water quality requirements that will protect human and ecological health. Disruption of thyroid-mediated actions is among the possible risks from chronic exposure to environmental contaminants. Endocrine disrupting compounds are generally of greater concern in this context than other trace contaminants because of the very low concentrations at which hormones induce physiological responses. Accordingly, a sensitive nuclear-based bioassay system was developed in order to evaluate environmental samples. A luciferase-reporter construct and the human thyroid receptor β (TR-β) construct in the human hepatoma cell line (HepG2) and human medulloblastoma cells (TE671) was evaluated for sensitivity. The transfected cells were exposed to the thyroid hormone, T3, in order to establish a lower thyroid hormone detection limit for the new bioassay procedure. The assay was then applied to environmental samples containing organics concentrated from final effluent derived from a conventional secondary wastewater treatment plant. The effluent samples activated thyroid receptor-mediated transcription. Also in this study, a two-dimensional gel electrophoresis (2D-DIGE) was used as an in vitro bioassay to look for wastewater related alteration of cellular protein expression in the human breast cancer cell T47D. Steps in this bioassay include the one-dimensional separation of proteins by isoelectric focusing followed by orthogonal electrophoresis to isolate the proteins. The consistency of test response was examined for wastewater-dependent up- or down-regulation of protein expression. Some proteins that were upregulated were preliminarily identified via mass spectrometry. Here, the procedure is used to provide direct information regarding the probable effects of residual hormones in treated wastewater on the activities of human, estrogen-responsive cells in cell culture.
9

Reproductive and Growth Responses of the Fathead Minnow (Pimephales Promelas) and Japanese Medaka (Oryzias Latipes) to the Synthetic Progestin, Norethindrone

Paulos, Peter M. 05 1900 (has links)
A commonly prescribed contraceptive, the synthetic progestin norethindrone (NET) inhibits ovulation in humans. However, ecotoxicological data are lacking. Preliminary tests produced an LC50 for NET of > 1.0 mg/L (96-hour, fathead minnow (FHM) and medaka) and a NOEC of 242.0 µg/L, a LOEC of 485.0 µg/L (7-day, growth for FHM and medaka). Reproductive testing revealed a LOEC for fecundity of 24.1 ng/L (21 days, medaka). Further testing confirmed the LOEC of 24.1 ng/L while defining a NOEC of 4.7 ng/L (28 days, medaka). Effect of NET in medaka life-cycle exposure at concentrations exceeding 4.7 ng/L was evident. Few females were present in the 24.7 ng/L exposure concentration, with none in the 104.6 ng/L. Egg production was significantly reduced at concentrations exceeding 4.7 ng/L. Additionally, weight, condition factor and somatic indices were significantly different in males exposed to concentrations exceeding 4.7 ng/L. For fecundity and sexual differentiation; the NOEC was 4.7 ng/L, the LOEC 24.6 ng/L; growth and somatic indices, the NOEC was more appropriately 0.9 ng/L, with effect evident at 4.7 ng/L. Sexual differentiation of the F1 population was similar to the F0. A defining result of this test was development of exceptionally large ovaries in NET- exposed female medaka, perhaps indicative of a threshold limit for exposure in these fish. Results of FHM life-cycle testing were similar, establishing a NOEC for fecundity of 0.9 ng/L, a LOEC of 4.8 ng/L. NET's inhibitory effect on gonadal development was obvious; GSI NOEC for males, 4.8 ng/L, and histological examination confirmed the presence of intersex development at elevated concentrations. Normal physical development and growth were impaired, generally at concentrations exceeding 24.1 ng/L. At exposure concentrations exceeding 4.8 ng/L, external sexual confirmation of fish was difficult; LOEC for finspot development in females, 4.8 ng/L. Sexual determination of the 97.1 ng/L exposure group was impossible; externally, all fish appeared male and internal examination revealed no gonadal development.
10

Naphthenic Acids Disrupt Courtship in Silurana tropicalis

Zhang, Wo Su 30 September 2020 (has links)
Neuroendocrine processes coordinate the behavioural, physiological, and seasonal aspects of reproduction. Some chemicals can disrupt the hypothalamus-pituitary-gonadal axis, impacting reproductive health. Naphthenic acids (NAs), the carboxylic acids in petroleum, are of emerging concern as they contaminate coastlines after oil spills and aquatic ecosystems of the Athabasca oil sands area. They are acutely toxic in fish and tadpoles and possibly endocrine disrupting at sublethal levels. I characterized courtship behaviours and disruption by NAs in the Western clawed frog, Silurana tropicalis. Courtship primarily consists of males producing low trills and achieving amplexus, a mating position where a male clasps a female. Adult frogs were exposed for five days to 20 mg/L NA, a dose low enough to not affect physical activity. In males, absolute calling activity was reduced. Other acoustic parameters such as dominant frequency, click rate, and trill length were not affected. Injecting human chorionic gonadotropin had a slight rescue effect. Vocalization and amplexus were both inhibited after exposure and restored after 2 weeks of recovery. However, calling behaviour did not predict competitive ability or mating success. In females, NA exposure reduced mating success, possibly through decreased attractiveness or receptivity. Receptivity can be indicated by attraction towards the sound of mating calls (phonotaxis), which is cryptic and subjective. I created an apparatus that measures phonotaxis by placing speakers inside traps with infrared lights to detect the time of entry. This novel method is widely applicable for low-visibility observations and studies of choice and preference. This work shows that an aquatic contaminant can reduce mating success in otherwise healthy frogs, and provides a detailed foundation for further investigation.

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