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  Services » Publications » Technical reports - by year » tr200908

Trace Elements in the Sediment of Waikato West Coast Estuaries

Report: TR 2009/08

Author: Andrew Rumsby,(Pattle Delamore Partners Ltd) 


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
(1179 kb, 168 seconds to download, 56k modem)


Table of contents

  Executive summary  ii
  Note on terms vi
1.0 Introduction 1
1.1 Project Scope 1
2.0 Sample collection and analysis 1
2.1 Method for sediment collection: 1
2.2 Water samples 2
2.3 Sample analysis 2
3.0 Guidelines 5
3.1 ANZECC sediment quality guidelines 5
3.2 Water Quality Guidelines 6
4.0 Sources of Contaminants in West Coast Estuaries 9
4.1 Organic Carbon 9
4.2 Trace Elements 10
4.3 Organic Compounds 11
5.0 Results 11
5.1 Sediment Samples 12
5.2 Comparison with ANZECC Sediment Quality Guidelines 17
5.3 Port Waikato Water Quality 18
6.0 Discussion 21
6.1 Comparison of sediment quality between harbours and background concentrations 21
6.2 Impacts on Marine Mammals 26
7.0 Conclusions 30
7.1 Aotea, Kawhia and Raglan Sediment Quality 30
7.2 Port Waikato 31
8.0 Recommendations 33
9.0 References 34
Appendix A Sampling Locations 37
Appendix B Background Soil Concentrations 44
Appendix C Aotea Harbour Result Summary Tables 45
Appendix D Kawhia Harbour Result Summary Tables 45
Appendix E Port Waikato Result Summary Tables 51
Appendix F Raglan Harbour Result Summary Tables 55
Appendix G Data Handling 58
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