New research led by The University of Queensland has provided the first comprehensive analysis of pesticide mixtures in creeks and rivers discharging to the Great Barrier Reef.

UQ’s School of Earth and Environmental Sciences researcher Associate Professor Michael Warne conducted the study with the Queensland Department of Environment and Science, and analysed 2600 water samples from 15 waterways that discharge into the Great Barrier Reef lagoon over a four-year period.

“While I knew many water samples would contain mixtures, I was shocked to find that essentially every sample contained mixtures of pesticides,” Dr Warne said.

“We found 99.8 per cent of the samples contained pesticide mixtures with up to 20 pesticides in any single water sample.

“The issue with having mixtures of pesticides is that as the number of pesticides increases the impact to aquatic ecosystems generally increases.

“This work strongly supports the inclusion of the pesticide reduction target in the Reef 2050 Water Quality Improvement Plan which aims to protect at least 99 per cent of aquatic organisms at the mouths of rivers from the adverse effects of all pesticides.”