Territory Stories

Developing an integrated long-term monitoring program for Darwin Harbour - Water quality pilot project WP2: Intra-annual water quality variability

Details:

Title

Developing an integrated long-term monitoring program for Darwin Harbour - Water quality pilot project WP2: Intra-annual water quality variability

Creator

Makarynska, Dina; Northern Territory. Department of Environment and Natural Resources. Water Resources Division

Collection

E-Publications; E-Books; PublicationNT; 22/2019

Date

2019-06-14

Location

Darwin Harbour

Abstract

The main purpose of the Intra-annual Water Quality Variability project is to examine temporal variability of surface water quality in Darwin Harbour to determine whether the current May and October survey periods are suitably representative to summarise Darwin Harbour water quality as well as to explore other design options to improve the capacity of the monitoring program to detect long-term changes in water quality. A project-specific field campaign was developed to collect surface water quality data over the period from May 2017 to October 2018 during neap tidal events along transect lines in the key areas of the Harbour: (1) Elizabeth River and East Arm (EA), (2) Blackmore River and Middle Arm (MA) and (3) Outer Harbour (OH). Physico-chemical parameters and chlorophyll fluorescence were measured along each transect using flow cell monitoring method that produced approximately 500 data points per 100 m. Additionally, intermittent grab sampling was undertaken for nutrients and chlorophyll a at density of approximately one per 2.5 km. Overall, the study produced 85 transects for each of 18 water quality parameters on 44 dates. To identify trends in spatial variation, the EA and MA transects were further subdivided into three polygons resulting in a total of 210 sub-transects for each parameter. Detailed parameter-specific assessments of surface water quality focussed on variability between consecutive days, months and four seasons. Hypothesis tests of similar means (ANOVA) and similar medians (Kruskal-Wallis) were conducted to investigate the difference in variability patterns for each parameter and each spatial area within neap tide periods.

Notes

Made available via the Publications (Legal Deposit) Act 2004 (NT)

Table of contents

1 Summary -- 2 Introduction -- 2.1 Background -- 2.1.1 Darwin Harbour: physical characteristics -- 2.1.2 Water quality in Darwin Harbour -- 2.1.3 DENR WQMP -- 2.2 Study Objectives -- 3 Method. -- 3.1 General approach -- 3.2 Field stations and monitoring dates -- 3.3 Measured parameters -- 3.4 Seasons -- 3.5 Field techniques -- 3.5.1 In-situ field measurements -- 3.5.2 Sample collection and analysis -- 3.6 Data analysis and visualisation -- 3.6.1 Data visualising techniques -- 3.6.2 Statistical parameters -- 3.6.3 Hypothesis testing -- 4 Results and discussion -- 4.1 ...... Depth -- 4.2 ...... Physico-chemical results -- 4.2.1 ........ Water temperature -- 4.2.1.1 ....... East Arm -- 4.2.1.2 Middle Arm -- 4.2.1.3 Outer Harbour -- 4.2.2 ........ Salinity and electrical conductivity -- 4.2.2.1 East Arm -- 4.2.2.2 Middle Arm -- 4.2.2.3 Outer Harbour -- 4.2.3 pH -- 4.2.3.1 East Arm -- 4.2.3.2 Middle Arm -- 4.2.3.3 Outer Harbour -- 4.2.4 Turbidity -- 4.2.4.1 East Arm -- 4.2.4.2 Middle Arm -- 4.2.4.3 Outer Harbour -- 4.2.5 Dissolved oxygen -- 4.2.5.1 East Arm -- 4.2.5.2 Middle Arm -- 4.2.5.3 Outer Harbour -- 4.3 .Nutrients - Nitrogen and Phosphorus -- 4.3.1 Summary statistics -- 4.3.2 Ammonia -- 4.3.2.1 East Arm -- 4.3.2.2 Middle Arm -- 4.3.2.3 Outer Harbour -- 4.3.3 Oxides of nitrogen -- 4.3.3.1 East Arm -- 4.3.3.2 .Middle Arm -- 4.3.3.3 Outer Harbour -- 4.3.4 Total filterable (dissolved) nitrogen -- 4.3.4.1 East Arm -- 4.3.4.2 Middle Arm -- 4.3.4.3 Outer Harbour -- 4.3.5 Total nitrogen -- 4.3.5.1 East Arm -- 4.3.5.2 Middle Arm -- 4.3.5.3 Outer Harbour -- 4.3.6 Soluble reactive phosphorus -- 4.3.6.1 East Arm -- 4.3.6.2 Middle Arm -- 4.3.6.3 Outer Harbour -- 4.3.7 Total filterable (dissolved) phosphorus -- 4.3.7.1 East Arm -- 4.3.7.2 Middle Arm -- 4.3.7.3 Outer Harbour -- 4.3.8 Total phosphorus -- 4.3.8.1 East Arm -- 4.3.8.2 Middle Arm -- 4.3.8.3 Outer Harbour -- 4.4 Phytoplankton biomass -- 4.4.1 Summary statistics -- 4.4.2 Chlorophyll -- 4.4.2.1 East Arm -- 4.4.2.2 Middle Arm -- 4.4.2.3 Outer Harbour -- 5 Summary of results -- 5.1 Parameter-specific trends -- 5.1.1 Physico-chemical parameters -- 5.1.2 Nutrients -- 5.1.3 Algal biomass -- 5.1.4 Coefficient of variation -- 5.1.4.1 Consecutive days -- 5.1.4.2 Monthly and seasonal variation -- 5.2 Trends for combined water quality -- 5.2.1 Monthly and seasonal variation -- 5.2.2 Spatial variability -- 5.3 Variability in natural factors controlling water quality -- 5.4 Study limitations -- 6 Conclusions and recommendations -- Recommendations -- 7 References -- 8 Acknowledgement -- 9 Appendix A: Metocean and hydrological conditions -- 9.1 Data sources -- 9.2 Rainfall -- 9.3 River discharge -- 9.4 Wind -- 9.5 Tides -- 9.6 Water temperature -- 10 Appendix B: Parameters vs downstream distance -- 10.1 Water temperature -- 10.2 Salinity -- 10.3 Turbidity -- 10.4 Dissolved oxygen -- 10.5 Ammonia -- 10.6 Oxides of nitrogen -- 10.7 Soluble reactive phosphorus -- 10.8 Chlorophyll a -- 11 Appendix C: Statistical tests-monthly variation -- 11.1 Water temperature -- 11.2 Salinity and electrical conductivity -- 11.3 pH -- 11.4 Turbidity -- 11.5 Dissolved oxygen -- 11.6 Ammonia -- 11.7 Oxides of nitrogen -- 11.8 Total filterable nitrogen -- 11.9 Total nitrogen -- 11.10 Soluble reactive phosphorus -- 11.11 Total filterable phosphorus -- 11.12 Total phosphorus -- 11.13 Chlorophyll

Language

English

Subject

Darwin Harbour water quality monitoring

Publisher name

Northern Territory Government

Place of publication

Palmerston

Series

22/2019

Format

348 pages : colour maps ; 30 cm.

File type

application/pdf

ISBN

9781743502082

Use

Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government

License

https://creativecommons.org/licenses/by/4.0/

Parent handle

https://hdl.handle.net/10070/754337

Citation address

https://hdl.handle.net/10070/775440


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