Abstract
Freshwater contamination with estrogenic endocrine-disrupting chemicals is a global issue with the potential to cause an array of detrimental effects on vertebrate and invertebrate taxa, reducing ecosystem health and biodiversity. However, relatively little research has been conducted to date on the state or extent of estrogenic contamination of New Zealand's surface waters. Accordingly, a survey of estrogenic contamination in twenty Otago freshwater sites included in the Otago Regional Council's State of Environment water quality monitoring programme was carried out bimonthly over a twelve-month period, with samples analysed via solid-phase extraction coupled with a 17β-estradiol (E2) radioimmunoassay. This was supplemented by an exploration of the survey's findings against a number of categories describing site environment, and of the relationships between measured estrogenicity and water quality data obtained by the Otago Regional Council for the same sites over the same time period, in order to evaluate what factors may be significant in contributing to or impacting the extent of estrogenic contamination observed in the survey.
The survey showed that estrogenic contamination was widespread across the Otago region, being detected in all sampling sites throughout the sampling period at levels consistent with other studies of estrogenic endocrine-disruptors in New Zealand. Levels of E2 measured for survey sites ranged from 0.03 – 0.80 ng/L, with an overall average level of 0.14 ng/L. Furthermore, significantly elevated levels of estrogenic material were measured during the summer sampling months. Of the site categories compared with measured estrogenicity in the survey, climate appeared the most influential, with drier sites having significantly higher levels of estrogenicity compared with wet sites, though this significance was not supported following Benjamini-Hochberg correction. Among the water quality variables compared with survey estrogenicity, pH had a significant positive relationship with E2, though this was also not supported following Benjamini-Hochberg correction. Lastly, implications of these findings for freshwater management in New Zealand are considered, including a discussion of the risk posed by the measured levels of estrogenicity; any overlaps of findings with other key issues to national water quality; and steps that would need to be considered in any efforts to integrate estrogenic contamination as a part of current and future plans and policies for New Zealand's water quality management.