Organochlorine contaminants in sediments of the Tauranga harbour, New Zealand

Abstract

DDT, DDE, and DDD (up to 0.5 ng g‐1per compound) and traces of dieldrin (< 0.1 ng g‐1), were detected in surficial sediments collected from four sites in the greater Tauranga Harbour. An elevated level of PCBs (19.9 ng g‐1) was identified in a Waikareao Estuary sample. PCB and DDT levels of up to 24.1 ng g‐1 and 5.38 ng g‐1respectively, were subsequently detected in other eastern shore Waikareao Estuary sediment samples. Higher levels of PCBs (68.6 and 73.8 ng g‐1) and DDTs (total 7.52 and 19.2 ng g‐1) were detected in sediments from two eastern shore stormwater drains identified as the likely sources of the PCB and DDT burden entering the Waikareao Estuary. Black, carbonaceous, coal-and asphalt‐like, paniculate material (98% loss of organic carbon on ignition), isolated by sieving a representative sediment sample, exhibited DDT and PCB levels which were respectively 85 and 6 times higher than was the case for other sieved fractions. © The Royal Society of New Zealand 1994.