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Trace Elements in the Sediment of Waikato West Coast Estuaries

TR 2009/08
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Report: TR 2009/08

Author: Andrew Rumsby,(Pattle Delamore Partners Ltd) 

Abstract

This report provides a description of the sediment quality of four west coast estuaries (Aotea Harbour, Kawhia Harbour, Raglan Harbour and the river mouth of Port Waikato) as well as the water quality of the Waikato River at Port Waikato.  Environment Waikato (EW) engaged Pattle Delamore Partners Limited (PDP) to prepare the report based on the results of water and sediment sampling of the estuaries undertaken by EW in 2008.

In 2008, as part of the regional estuary monitoring programme, EW undertook testing of the levels of trace elements and organic compounds in sediments of the inter-tidal sand and mudflats from five sites in Whaingaroa (Raglan) Harbour, 19 sites in Port Waikato, nine sites in Aotea Harbour and seven sites in Kawhia Harbour. 

EW commissioned PDP to carry out this project with the following objectives:

  1. To compare the concentrations of the various water and sediment sampling parameters with expected background concentrations, and to identify and discuss any levels of enrichment.
  2. To compare the results against water and sediment quality guidelines (ANZECC, 2000) where they exist. 
  3. To comment on the significance of any trace organic compounds detected, their possible sources and future trends in their levels in the environment. 
  4. To comment on whether there are any discernible spatial trends observed within the concentration data.
  5. For the six water samples at Port Waikato, comment on the possible significance of the estrogenic compound results and microbiological load in respect of potential impacts upon marine mammals, in particular upon Maui’s dolphins using the river mouth.

Trace Elements in the Sediment of Waikato West Coast Estuaries [PDF, 1.1 MB]