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PH22 Large-Scale Investigations of Contaminated Sediments
(PH245) Organic contaminants in New Zealand coastal sediments: a risk-based assessment.
Hickey, C1, Mills, G2, 1 National Institute of Water and Atmospheric Research (NIWA), Hamilton, New Zealand2 Diffuse Solutions Ltd, Hamilton, New Zealand
ABSTRACT- Organic contaminant data from New Zealand coastal sediments were compiled and analysed to i) determine the concentrations of key contaminants in NZ coastal sediments, ii) assess potential effects on sediment-dwelling biota, and iii) to obtain an international perspective by comparing NZ sediment contaminant levels with the US National Status & Trends Program sediment database. The most commonly reported chemicals in NZ sediments were polycyclic aromatic hydrocarbons (PAH), organochlorine pesticides (DDT, lindane, chlordane, and dieldrin), and polychlorinated biphenyls (PCB). Concentrations were compared with ANZECC interim sediment quality guidelines (ISQGs) to assess potential for adverse biological effects. ISQG-high (i.e., 50% probability of effect) levels were exceeded most frequently for DDT, mostly in localised port/wharf areas or in areas associated with point-source contaminant inputs. ISQG-low (i.e., 10% probability of effects) levels were exceeded more frequently: 60% of samples exceeded such levels for DDT, 19% for both lindane and dieldrin, 13% for PAH, and 6% for PCBs, mainly in urbanised estuaries. Based on comparisons with ISQGs, organochlorine pesticides, in particular DDT, are the contaminants most likely to affect biota residing in NZ coastal sediments. Median concentrations were similar in NZ and USA for DDT and PAH, higher in NZ for PCB and dieldrin, and lower in NZ for chlordane. Highest levels in NZ were considerably lower than those present in USA. Multiple SQG exceedance frequently occurred at NZ sites suggesting that additive may increase potential effects. This analysis suggests that biological impacts will be largely chronic, sub-lethal effects.
Key words: Stormwater, Sediment , Guidelines, Risk assessment
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