Contaminant pathways in Port Curtis: Final report - OzCoasts

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Contaminant pathways in Port Curtis: Final report9: Conclusions and future directionsthe ecosystem and the need for reliable baseline information and strongenvironmental management.In the future, is it envisaged that the Port Curtis Integrated Monitoring Program(PCIMP) and the Centre for Environmental Management (based at the Gladstonecampus of Central Queensland University) will carry on legacy of the CRC. PCIMPis a consortium of members from 14 bodies representing industry, government(both local and state), research institutions and other stakeholders to develop acooperative, integrated monitoring program for monitoring the ecosystem health ofPort Curtis. A strong, long-term, annual monitoring program building on the initialgroundwork established by the CRC is being formulated by PCIMP members inconsultation with local stakeholders. Research will focus on water and sedimentquality—particularly bioavailable contaminants—and on mangrove ecosystems.Results will be presented to the community in the form of an Ecosystem HealthReport Card for Port Curtis.Based on the CRC studies of the last six years, we suggest some directionsfor future contaminants management and research, as described in the followingsections (sections 9.2.1–9.2.4).9.2.1 Risk-based managementThe screening level risk assessment (SLRA) illustrated the utility of using a riskbasedapproach to contaminant management. Owing to limited resources, theCRC was not able to assess the risks posed by many organic contaminants. Werecommend that this issue now be covered, but with a stage-based approach. TheCRC research has shown the value of using contaminant bioaccumulation as anindicator of ecosystem health. A first stage would therefore be the measurement oforganic contaminants in indicator organisms in Port Curtis. Further investigationsmay be necessary if bioaccumulated organic contaminants prove to be significant.Mercury in piscivorous fish such as barramundi can be elevated owing to foodchain biomagnification. This is a regional issue of importance and should not beforgotten given the large recreational and commercial fishing industries presentin Port Curtis and surrounding regions. The characterisation of mercurybioaccumulation and biomagnification through food webs over the coastal regionof the whole Central Queensland region is considered appropriate.115
Contaminant pathways in Port Curtis: Final report9: Conclusions and future directions9.2.2 Improved monitoringThe Contaminant Pathways study and the SLRA have shown the value of ‘goodquality data’. It is recommended that future monitoring adopt and enforce rigorousquality assurance protocols to ensure quality is maintained.As noted earlier, contaminant concentrations may fluctuate over various timescalesin Port Curtis. Such variations are not easily picked up with a discretesampling approach. Time-integrated monitoring such as biomonitoring usingdeployed organisms (e.g. oysters) and chemical surrogates such as diffusivegradients in thin films (DGT) for metals and solvent-filled dialysis cells for organics(passive samplers) is therefore recommended. Seasonal monitoring may also beconsidered to determine if there are any seasonal fluctuations to contaminantloads in Port Curtis.9.2.3 Ability to predict contaminants concentrations and effectsA key tool in sustainable management is the ability to predict impacts. Werecommend that the further development of the Port Curtis hydrodynamic model inconjunction with contaminant data and a subsequent suite of predictive models ispursued. The model should be expanded to include The Narrows region and someof the major estuaries in Port Curtis to assist in understanding the contribution ofmetal load from point sources, and flows from the Fitzroy to Port Curtis. Predictivemodels of metal bioaccumulation and biological impact (or establishing ifenvironmental harm has occurred) are also worthy of consideration. The effect ofpulse versus continuous discharges on bioaccumulation should also be pursued.Information could result in management changes for a more favourable controlledrelease of contaminants at point source discharges.9.2.4 Future concernsIt is not easy to predict the priorities for contaminant management over the nextdecade. It is necessary to keep a watching brief on emerging issues such as theintroduction of new ‘contaminants of potential concern’ (COPCs) from developingindustries. Unforseen events such as oil spills and resulting PAH contaminationwill always be a threat in a busy commercial port and stringent protocols should bein place to manage and subsequently assess the impacts of such events. Ross(2002) recently reported a survey of acid sulfate soils (ASS) in the CentralQueensland coast and found high occurrence of these soils on the coastal plainalong the Curtis and Capricorn coasts and at Shoalwater Bay and Broadsound.ASS are soils containing sulfides or acid-producing soil layers resulting from theoxidation of sulfides. When exposed to air, sulfides are oxidised, producing sulfuric116
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Contaminant pathways in Port Curtis: Final report - OzCoasts

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