Sediment quality at muddy intertidal sites in

The sediment quality was assessed at muddy intertidal sites in Canterbury. We undertook this assessment to determine what the concentrations of contaminants in the sediments are and if could be influencing intertidal marine life. We collected sediment samples from 18 sites: Saltwater Creek, Brooklands Lagoon, five sites in the Avon-Heathcote Estuary/Ihutai, four sites in Lyttelton Harbour/Whakaraupō, Port Levy/Koukourarata, Okains Bay, four sites in Akaroa Harbour and the Opihi River mouth. We tested the sediment from these sites to determine the level of selected contaminants: arsenic, copper, chromium, cadmium, mercury, lead, nickel, zinc and hydrocarbons (petrol and oil residues). One criterion for selecting a sampling site was that it had fine, muddy, sediment rather than coarse, sandy, sediment. To determine whether levels of selected contaminants were caused by human activity, we compared our results to levels in nearby soil. We also compared levels among sites in each of the harbours and within the estuary. Finally, to assess whether the plants and animals of the mudflats could be affected by any contamination, we compared our measurements to national sediment quality guideline values. We found that sediment from Brooklands Lagoon, Port Levy/Koukourarata, Okains Bay, Opihi River mouth, two sites in Lyttelton Harbour/Whakaraupō, and two sites in Akaroa Harbour is no