HEAVY METALS IN THE SEDIMENTS OF NORTHERN MORETON BAY, QUEENSLAND, AUSTRALIA James Peter Brady B Ed (Sec), B AppSc (Chem), M AppSci (Research)(Chemistry) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy School of Chemistry, Physics and Mechanical Engineering Science and Engineering Faculty Queensland University of Technology 2015 i Keywords Bioavailability assessment; Bramble Bay; Contamination; Deception Bay; Enrichment Factor; Fraction analysis; Heavy metal distribution; Heavy metal enrichment; Modified Pollution Index; Nemerow Pollution Index; Pollution index; Sediment quality guidelines; Source apportionment; X-ray Fluorescence. Heavy metals in the sediments of Northern Moreton Bay, Queensland, Australia i ii Abstract Moreton Bay is located 14 kilometres east of the Brisbane Central Business District in Queensland, Australia. The Northern half of Moreton Bay (north of the Brisbane River) encompasses Deception and Bramble Bays, which are sanctuaries to endangered wildlife and migratory seabirds, along with a significant seafood industry. There have been few attempts to assess heavy metal pollution in Moreton Bay, resulting in a lack of understanding of heavy metal sources, distributions, temporal behaviour and bioavailability. The lack of this information has resulted in limited capacity to accurately assess the risk human health from heavy metals present in Northern Moreton Bay and to the ecosystem. This is the first work since the late 1970’s to assess sediment contamination within Northern Moreton Bay, model the pollution sources and heavy metal distributions and finally propose improved Sediment Quality Guidelines, pollution indices and a routine heavy metals monitoring program in order to assess and monitor the risk posed by heavy metals in the weak acid soluble fraction of the sediments in Deception and Bramble Bays. Sediment samples were taken from Deception and Bramble Bays and examined for heavy metals content using X-ray Fluorescence and acid extraction. Advanced chemometric techniques were used to provide source apportionment, with marine sediments, shipping related activities and antifouling coatings being identified as sources of pollution. Fraction analysis was also performed to provide a risk assessment of bioavailable metals. ii Heavy metals in the sediments of Northern Moreton Bay, Queensland, Australia iii Generally, the results indicated that Pb, and As pollution was of concern in all three studies. In addition, the XRF study identified Zn pollution in the mouth of the Caboolture River to be a concern. Enrichment of Hg and Cd was identified as a serious concern in the acid extraction studies for both Bramble and Deception Bays. Source apportionment studies in Bramble and Deception Bays found that there were three common sources of heavy metals in the sediments of Northern Moreton Bay: marine sediments, shipping and antifouling coatings. A fourth mixed source was identified at Bramble Bay, whilst Hierarchical Cluster Analysis of the XRF data in Deception Bay identified marine sediments and shipping as two likely sources of heavy metals pollution. Limitations with the ability of current sediment pollution indices to give a whole sediment pollution assessment whilst accounting for complex sediment behaviours were identified. A hybrid sediment pollution index was developed that accounted for complex sediment behaviours and was assessed against existing studies. Limitations with the development of Sediment Quality Guidelines (SQGs) were also identified and addressed through the development of SQG decision trees which were based on the use of pollution indices. This addressed limitations due to variation of geographical regions, resilience of benthic organisms and the size of datasets required to set thresholds. The proposed changes were developed so that they required minimal changes to existing SQG decision trees and could be implemented without difficulty. The source apportionment and fraction analysis of Deception and Bramble Bays provide the first in depth assessment and modelling of heavy metal sediment pollution sources in Northern Moreton Bay. The proposed changes to the development and application of Sediment Quality Guidelines and hybrid pollution index are innovative and will potentially provide new insight into risk assessment of polluted sediments. Heavy metals in the sediments of Northern Moreton Bay, Queensland, Australia iii iv Journal Articles Brady, J. P., Ayoko, G. A., Martens, W. N., & Goonetilleke, A. (2014). Enrichment, distribution and sources of heavy metals in the sediments of Deception Bay, Queensland, Australia. Marine Pollution Bulletin, 81(1), 248-255. Brady, J.P., Ayoko, G.A., Martens, W.N., Goonetilleke, A., 2014. Temporal trends and bioavailability assessment of heavy metals in the sediments of Deception Bay, Queensland, Australia. Marine Pollution Bulletin. 89(1) 464-472. Brady, J. P., Ayoko, G. A., Martens, W. N., & Goonetilleke, A. (2015). Weak acid extractable metals in Bramble Bay, Queensland, Australia: Temporal behaviour, enrichment and source apportionment. Marine Pollution Bulletin 91(1) 380-388 Brady, J. P., Ayoko, G. A., Martens, W. N., & Goonetilleke, A. (2015). Development of a hybrid pollution index for heavy metals in marine and estuarine sediments Environmental Monitoring and Assessment 187(5). Brady, J. P., Ayoko, G. A., Martens, W. N., & Goonetilleke, A. The case for an index-based approach to developing decision trees in Sediment Quality Guidelines for heavy metals contamination, submitted to Environmental Toxicology and Chemistry. iv Heavy metals in the sediments of Northern Moreton Bay, Queensland, Australia v Table of Contents Keywords .................................................................................................................................................i Abstract .................................................................................................................................................. ii Table of Contents .................................................................................................................................... v List of Figures ........................................................................................................................................ix List of Tables .........................................................................................................................................xi List of Abbreviations ........................................................................................................................... xiii Statement of Original Authorship ........................................................................................................ xiv Acknowledgments ................................................................................................................................. xv CHAPTER 1: INTRODUCTION ....................................................................................................... 1 1.1 Background .................................................................................................................................. 1 1.2 Context ......................................................................................................................................... 1 1.3 Research aims .............................................................................................................................. 2 1.4 Paper 1: Enrichment, distribution and sources of heavy metals in the sediments of Deception Bay, Queensland, Australia .......................................................................................................... 4 1.5 Paper 2: Development of a hybrid pollution index for heavy metals in marine and estuarine sediments ..................................................................................................................................... 4 1.6 Paper 3: The case for an index-based approach to developing decision trees in Sediment Quality Guidelines for heavy metals contamination .................................................................... 5 1.7 Paper 4: Temporal trends and bioavailability assessment of heavy metals in the sediments of Deception Bay, Queensland, Australia ........................................................................................ 6 1.8 Paper 5: Weak acid extractable metals pollution of Bramble Bay, Queensland, Australia: Temporal behaviour, enrichment and source apportionment ....................................................... 7 1.9 Signficance, scope and definitions ............................................................................................... 8 1.10 Outline ......................................................................................................................................... 8 1.11 References .................................................................................................................................... 9 CHAPTER 2: LITERATURE REVIEW ......................................................................................... 11 2.1 Background ................................................................................................................................ 11 2.2 Marine and estuarine environments ........................................................................................... 11 2.2.1 Sediment behaviour in marine and estuarine environments ......................................................