Pesticide sources, exposure and risk in the Great Barrier Reef catchments and lagoon


The runoff of pesticide residues has been identified as a water quality concern in the GBR catchment area. We have conducted monitoring programs to examine the land-based sources, transport, persistence and fate of these chemicals from the paddock scale through to the GBR lagoon. TropWATER’s Catchment Reef Research Group members have been involved in innovative studies examining pesticide monitoring applications involving rainfall simulation and furrow irrigation at the paddock scale as well as the use of passive samplers to predict loads.

Our research has highlighted that herbicide residues are easily detectable throughout GBR catchment waterways and in the adjacent river flood plumes. We have conducted several risk-based assessments for pesticides in the GBR catchment area and lagoon finding that the greatest risk is within freshwater wetlands and estuarine locations.

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Further Reading

Davis, A.M., Pearson, R.G., Butler, B. & Brodie, J.E. 2017. Review and conceptual models of agricultural impacts and water quality in waterways of the Great Barrier Reef catchment area. Marine and Freshwater Research, 68, 1–19.

Davis, A.M., Tink, M., Rohde, K., & Brodie, J.E. 2016. Urea contributions to dissolved ‘organic’ nitrogen losses from intensive, fertilised agriculture. Agriculture, Ecosystems and Environment 223, 190-196.

Davis, A.M., & Pradolin, J. 2016. Precision herbicide application technologies to decrease herbicide losses in furrow irrigation outflows in a northeastern Australian cropping system. Journal of Agricultural and Food Chemistry 64, 4021–4028.

Davis, A.M. Lewis, S.E. Brodie, J.E. Benson, A. 2014 The potential benefits of herbicide regulation: A cautionary note for the Great Barrier Reef catchment area. Science of the Total Environment 490, 81-92.

Davis, A.M. Thorburn, P.J. Lewis, S.E. Bainbridge, Z.T. Attard, S.J. Milla, R. Brodie, J.E. 2013. Environmental impacts of irrigated sugarcane production: Herbicide run-off dynamics from farms and associated drainage systems. Agriculture, Ecosystems and the Environment 180, 123-135.

Davis, A.M. Lewis, S.E. Bainbridge, Z.T. Glendenning, L. Turner, R. Brodie, J.E. 2012. Dynamics of herbicide transport and partitioning under event flow conditions in the lower Burdekin region, Australia. Marine Pollution Bulletin 65, 182-193.

Kennedy, K. Schroeder, T. Shaw, M. Haynes, D. Lewis, S. Bentley, C. Paxman, C. Carter, S. Brando, V. Bartkow, M. Hearn, L. Mueller, J.F. 2012. Long term monitoring of photosystem II herbicides – Correlation with remotely sensed freshwater extent to monitor changes in the quality of water entering the Great Barrier Reef, Australia. Marine Pollution Bulletin 65, 292-305.

Lewis, S.E. Silburn, D.M. Kookana, R.S. Shaw, M. 2016. Pesticide behaviour, fate and effects in the tropics: an overview of current state of knowledge. Journal of Agricultural and Food Chemistry 64, 3917-3924.

Lewis, S.E. Schaffelke, B. Shaw, M. Bainbridge, Z.T. Rohde, K.W. Kennedy, K.E. Davis, A.M. Masters, B.L. Devlin, M.J. Mueller, J.F. Brodie, J.E. 2012. Assessing the additive risks of PSII herbicide exposure to the Great Barrier Reef. Marine Pollution Bulletin 65, 280-291.

Lewis, S.E. Brodie, J.E. Bainbridge, Z.T. Rohde, K.W. Davis, A.M. Masters, B.L. Maughan, M. Devlin, M.J. Mueller, J.F. Schaffelke, B. 2009. Herbicides: A new threat to the Great Barrier Reef. Environmental Pollution 157: 2470-2484.

Melland, A.R. Silburn, D.M. McHugh, A.D. Fillols, E. Rojas-Ponce, S. Baillie, C. Lewis, S. 2016. Spot spraying reduces herbicide concentrations in runoff. Journal of Agricultural and Food Chemistry 64, 4009-4020.

Novic, A.J. Ort, C. O’Brien, D.S. Lewis, S.E. Davis, A.M. Mueller, J.F. 2018. Understanding the uncertainty of estimating herbicide and nutrient mass loads in a flood event with guidance on estimator selection. Water Research 132, 99-110.

Novic, A.J. O’Brien, D.S. Kaserzon, S.L. Hawker, D.W. Lewis, S.E. Mueller, J.F. 2017. Monitoring herbicide concentrations and loads during a flood event: a comparison of grab sampling with passive sampling. Environmental Science and Technology 51, 3880-3891.

O’Brien, D. Lewis, S. Davis, A. Gallen, C. Smith, R. Turner, R. Warne, M. Turner, S. Caswell, S. Mueller, J.F. Brodie, J. 2016. Spatial and temporal variability in pesticide exposure downstream of a heavily irrigated cropping area: the application of different monitoring techniques. Journal of Agricultural and Food Chemistry 64, 3975-3989.

Oliver, D.P. Anderson, J.S. Davis, A. Lewis, S. Brodie, J. Kookana, R. 2014. Banded applications are highly effective in minimising herbicide migration from furrow-irrigated sugar cane. Science of the Total Environment 466-467, 841-848.


Dr Aaron Davis


P: +61 7 4781 5989



Dr Stephen Lewis


P: +61 7 4781 6629

Find out more Email Us Phone 07 4781 4073