Antifouling biocides in marinas: measurement of copper concentrations and comparison to model predictions for eight Auckland sites

The use of copper-based antifouling paints on vessel hulls in New Zealand has increased significantly since organotin based products were banned for use on recreational vessels in 1988. Copper is now found in almost all antifouling paints in New Zealand and these products therefore represent a potentially significant source of copper to the marine environment. A recent project for the New Zealand EPA (Environmental Protection Authority) modelling biocides released from antifouling paints applied to vessels suggested that in many New Zealand marinas, including several in Auckland, copper concentrations could be above guidelines for protection of marine aquatic life (Gadd et al. 2011). Given these high predictions, a study was designed to measure the copper concentrations in the water column of Auckland marinas to provide a preliminary validation of these model results and to investigate the likelihood for environmental effects on aquatic biota. A further aim of this study was to measure export of copper from a marina to the wider coastal environment (e.g., the Waitemata Harbour).

A survey was undertaken of eight marinas in Auckland, namely: Gulf Harbour, Westhaven, Westpark, Bayswater, Half Moon Bay, Pine Harbour, Milford and Orakei. At each marina three water samples were collected and analysed for dissolved and total copper, zinc, chromium, arsenic and iron; and a single sample from the middle of each marina was analysed for the co-biocide diuron. Water samples were also collected from the Waitemata Harbour as „reference‟ samples. The flux of copper from Westpark Marina was examined by sampling hourly over a complete tidal cycle to provide an estimate of the copper inputs, outputs and net flux. ...

Auckland Council technical report TR2012/033