Abstract
Estrogenic pollution, defined as the presence of estrogens or estrogen-mimicking compounds in the environment, can cause feminization and reduced embryonic survival of numerous species, and whole-ecosystem disruption in freshwater environments. Agricultural and wastewater effluents in Aotearoa New Zealand have previously been found to contain high levels of these compounds, with estrogenic pollution also reported in aquatic environments. However, the state of estrogenic pollution within the Otago region (Ōtākou) has not been well characterized. Previous work in the Lokman laboratory has suggested that 17β-estradiol is present in 20 river sites throughout Otago. Therefore, this thesis aimed to survey the same 20 sites for a wider range of estrogenic compounds (estrone [E1], 17α-estradiol [17α-E2], 17β-estradiol [17β-E2], estriol [E3], ethinylestradiol [EE2], bisphenol A [BPA], nonylphenol [NP], and five conjugated estrogens) as well as biological estrogenic activity in order to further investigate contamination in the region. Sites with agricultural (Taieri River) and urban (Cromwell oxidation ponds) influence were also investigated as potential sources of pollution. Developing sensitive chromatographic methods to detect trace levels of these compounds was a secondary aim. Solid-phase extraction (SPE) was used to extract target compounds from grab samples from these sites, before the extracts were analyzed using liquid chromatography-mass spectrometry (LCMS) and the yeast estrogen screen (S-YESMD assay). Conjugated compounds could not effectively be chromatographically separated, so were excluded from analysis, while matrix effects likely prevented the accurate LCMS analysis of free compounds. Two sites throughout Otago had estrogenic activity at levels that indicate a possible ecological risk as determined by effect-based trigger values (EBTs): Catlins at Houipapa (site O_T; 0.57 ± 0.13 ng/L estradiol equivalence [EEq]) and Hāwea at Camphill Bridge (site O_K; 0.22 ± 0.09 ng/L EEq). 17α-E2 was found below detection limits at Catlins at Houipapa, indicating a potential agricultural source of the estrogenic activity as it is the most abundant form of estrogen in cattle. No significant estrogenic pollution was detected in the Taieri or Cromwell sites. The results from this thesis suggest that harmful levels of estrogenic pollution may be present in the Otago region. Further studies which focus on developing and applying robust analytical methods could fully determine the scale of this pollution and thus the ecological risk posed to freshwater environments in Otago.