A multipronged approach to inform ecological risks of emerging organic contaminants in surface water and sediment in the estuarine-receiving environment of Tauranga Harbour, Bay of Plenty, New Zealand

Increasing coastal urbanisation is a continuous stressor on coastal ecosystems. Emerging organic contaminants (EOCs) comprise thousands of chemicals whose environmental fate and effects are not all well understood. A study of 96 EOCs was undertaken in Tauranga Harbour, New Zealand, with surficial sediments collected and passive sampling devices (PSDs) deployed at 12 sites. Per- and polyfluorinated alkyl substances (PFAS), glyphosate/aminomethylphosphonic acid (AMPA), and chloroxylenol were detected in PSDs only, while nonylphenol, bisphenol A, ketoprofen, salicylic acid, meclofenamic acid, UV filter chemicals and antifouling agents were only detected in sediment. Methyl paraben was the only EOC detected in both phases. Lipophilic phthalate plasticisers, pyrethroid insecticides, brominated diphenyl ether flame retardants and polycyclic musk fragrances were only measured in sediment. Phthalate plasticisers were ubiquitous while pyrethroid insecticides were detected at 8 sites. Steroid estrogens, phosphate flame retardants, wastewater markers, and the anti-corrosive benzotriazole were not detected. Generally, EOC concentrations in sediment and water from Tauranga Harbour are low when compared to other countries, with higher concentrations observed closest to the city of Tauranga. A qualitative ecological risk assessment of EOCs was undertaken using a risk quotient (RQ) approach. Ecological risk from dissolved EOCs was low to negligible with concentrations several orders of magnitude lower than effects concentrations. Sediment concentrations of EOCs were generally one order of magnitude below ecological effects concentrations, however five EOCs presented potential risks with exceedances recorded across 6 sites. Highest RQs quotients were 7.7 for monobutyl phthalate acid ester and 5.0 for cis-permethrin.