DDT, DDE, and DDD (up to 0.5 ng g -1 per 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 grespectively, 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.
Freshwater mussels incubated in the effluent of a kraft pulp and paper mill rapidly accumulated resin acids and fichtelite in their tissues, approaching a steady state in 7 d or less. Mean bioconcentration factors (BCFs) for individual resin acids varied from 110 to 330 L/kg dry wt. for 14‐chlorodehydroabietic acid and abietic acid, respectively. The mean BCF for fichtelite was 4,900 L/kg dry wt., at least an order of magnitude greater than that of the resin acids. Resin acids were depurated rapidly from mussel tissue (biological half‐lives of 3 d), whereas fichtelite concentrations declined more slowly (biological half‐life 12 d). Depuration kinetics for these compounds appeared to be described by a first‐order process. The possibility that the uptake process for fichtelite is zero order is explored.
Biota species were collected in February 1992 from the Waikareao Estuary, according to availability, from the ten sampling stations (Figure 1) utilised in an earlier the sediment study (Burggraaf et al. 1994). The species examined were: Macomona liliana (wedge shell), a surface deposit feeder that resides at depths of up to 10 cm and feeds by means of an inhalant siphon extending to the surface, Saccostrea glomerata (New Zealand rock oyster) that feeds by filtering suspended particles from the water column, and Amphibola crenata (mud snail) a deposit feeder that feeds on micro-organisms and organic detritus at the sediment surface. In addition M. liliana, S. glomerata and sediment were collected from an eleventh site (W5') adjacent to site W5.The methodology of Wilcock et al. (1993), applied to the analyses of technical chlordane residues in New Zealand biota species, was utilised in this study. After collection biota were depurated for 12 hr in saltwater, before freezing at -20°C. Samples were then thawed, shelled, washed sequentially with tap water and distilled water, and freeze dried. Freeze dried material was ground (mortar and pestle) and extracted in a Soxhlet apparatus with CHCl 3 . The resulting solution was concentrated to ca 1 mL and transferred to a weighed sample vial. After overnight evaporation at 45°C, the sample vial was reweighed to determine the lipid content. The lipid extracts constituted 11.6% (n = 37, CV = 8.8%), 4.1% (n = 45, CV = 15%) and 5.5 % (n = 16, CV = 12.8%) of the freeze dried S. glomerata, M. liliana, A. crenata specimens respectively.
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