Aquatic environmental degradation occurs from multiple chemical and biological stressors. Much is known about the effects of metals and legacy organic contaminants, and past and current regulatory efforts are reducing the impacts of these – think banning DDT, perfluorinated compounds, and lead from paint and petrol. However, an even larger set of chemical stressors – emerging organic contaminants (EOCs) – may be significant contributors to aquatic contamination, representing increased risk to human and ecological health.
Significant issues addressing EOCs are the huge number of disparate chemicals being used by human activities, multiple sources to the environment (e.g., sewage, stormwater, landfill leachate, agriculture, horticulture, aquaculture), and the varying and subtle, yet potentially profound effects they can exhibit.
We are addressing these knowledge gaps through an effect-directed analysis (EDA) methodology, which allows biological effect endpoints to direct the chemical discovery process. Extracts from passive sampling devices (PSDs) deployed in water and surficial sediments collected at multiple sites in a catchment with urban landuse (Whau Estuary, Auckland) and mixed landuse (New River/Oreti, Southland) have been tested through in vitro bioassays selected to cover multiple toxicological endpoints (e.g., toxicity to bacteria, photosynthesis inhibition, activation of xenobiotic metabolism pathways, interference with endocrine hormone receptors). A selection of extracts with significant bioassay activity were chemically fractionated and the fractions re-tested. Concurrent chemical analysis was undertaken with the biological testing to provide an understanding of the chemicals responsible for the toxicological endpoints.
This presentation summarises our experience applying this approach for the first time in New Zealand.