Aquatic environments are increasingly exposed to a myriad of organic chemicals as human populations expand their environmental influence. Major sources of such chemicals include wastewater treatment plant effluent and rainfall runoff from urban and agricultural areas. Biodegradation is a key removal process for these chemicals, but quantitative data on biodegradation rate constants (k) across diverse environment types remain scarce. Most existing data come from rivers in temperate and Mediterranean-climate regions, leaving substantial gaps for subtropical and tropical systems, reservoirs, estuaries, and marine environments. This scarcity introduces large uncertainties into chemical persistence and exposure assessments.
This project addressed two empirical gaps. First, it quantified spatial variability in k for over 100 organic chemicals across seven distinct aquatic environments in Queensland - spanning freshwater rivers, a reservoir, an estuary, mangroves, and coastal marine systems - using a modified OECD 309 laboratory simulation test. Results were compared with an equivalent dataset from 18 European riverine environments. Second, this project evaluated the environmental relevance of the modified OECD 309 laboratory simulation test through a direct laboratory - field comparison at a subtropical riverine site (Gowrie Creek, southeast Queensland) - one of the first such comparisons reported in the literature.
Conference Abstracts
Weir, L., Posselt, M., Chanson, H., Mueller, J. & McLachlan, M. Estimating surface-water travel time in a wastewater impacted river: a comparison of transport and hydraulic models, Workshop on Environmental Fluid Mechanics, Geophysical Flows and Modelling 2024, Australia, 26 September 2024.
Weir, L., Tian, R., Mueller, J. & McLachlan, M. From river to sea: Spatial variation in chemical biodegradation rates applying a modified OECD 309 Laboratory experiment, What’s In Our Water, Canberra, Australia, 29-31 October 2024.
Weir, L., Tian, R., Posselt, M., Chanson, H., Mueller, J. & McLachlan, M. From lab to field: A comparison of the biodegradation rates of organic chemicals in a subtropical river, SETAC Australasia, New Zealand, 25-28 August 2025.
Weir, L., Tian, R., Posselt, M., Mueller, J. & McLachlan, M. Biodegradation rates of organic chemicals in a subtropical river: From laboratory to field, SETAC Europe 36th Annual Meeting, The Netherlands, 17-21 May 2026.
Research Outputs
Prizes/Awards
- 2024 What's In Our Water conference, Best Student Presentation.
- 2025 SETAC Australasia Student Travel Grant.
