What Have We Learnt From 14 Years of Marine Dediment Chemistry Monitoring in the Auckland Region?

In 1998, the Auckland Regional Council (now Auckland Council) initiated a sediment chemistry monitoring programme aimed at assessing the spatial distribution of, and temporal trends in, key chemical contaminants across the region?s urban estuaries, harbours, and sheltered open coast. Over the subsequent 14 years important lessons have been learned concerning factors such as QA procedures and reporting, consistency of methods and the influence of analytical variability. As a result the programme has recently undergone significant review and restructure and improvements have been achieved including the consolidation of three originally separate programmes. Substantial data analysis has been carried out and results (including trends) will be presented for copper, lead, zinc and polycyclic aromatic hydrocarbons (PAHs). Of particular interest is that the early patterns of linear increases in zinc and copper (and decreases in lead) have not necessarily persisted, and recent data illustrate that changes over time are more complex and variable than might have been expected. Consideration of other potential sources of contaminants (such as marinas) and implications for the ecological health of the marine receiving environment will also be discussed.