Report: TR 2012/38
Author: SJ Clearwater (NIWA), T Valler (University of Waikato)
NIWA was commissioned by the Waikato Regional Council to survey contaminants in urban stream sediments in Hamilton and determine if sediment-associated contaminants are likely to inhibit restoration of these waterways.
The focus of the present study was on sediment associated contaminants. Dissolved or waterborne contaminant concentrations were not evaluated, however dissolved contaminants can significantly impact urban streams.
In June 2011 sediments were sampled at 27 locations in streams in the city of Hamilton and in May 2012 a subset of these locations was sampled again. Concentrations of up to 23 elements in stream sediments were compared.
|1.2||Site selection, contaminant analysis and toxicity testing||11|
|1.3||Comparison with sediment quality guidelines||11|
|1.4||Establishing current "background" concentrations and contaminant sources||12|
|2.4||Amphipod toxicity testing||19|
|3||Results and discussion||20|
|3.1||Grain size and organic carbon content||20|
|3.2||Sediment organochlorines and polycyclic aromatic hydrocarbons||22|
|3.3||Amphipod toxicity test||23|
|3.4||Sediment metals 2011 and 2012||24|
|3.5||Summary of guideline exceedance and amphipod results for each site||32|
|3.6||Peacockes tributary of the Mangkotukutuku Stream||37|
|3.7||Rukuhia and Te Anau tributaries of the Mangakotukutuku Stream||37|
|3.8||Normandy A and Graham A||37|
|3.11||Bankwood Park and Parana Park||41|
|Appendix A: Sediment contaminant concentrations||47|
|Appendix B: Sediment metal concentrations||68|