RRRD038 Progress update

November 2012

Science Summary:

Objective 1: Ascertain the half lives in water and exposure of key pesticides in the GBR catchment area and lagoon

Wetland component:

-  Preliminary results suggest that elevated levels of herbicides (above ecological protection guidelines) persist throughout Barratta Creek over much of the year even extending into the Ramsar internationally recognised wet land in the lower reaches of the creek.

Marine component:

-  Preliminary data analyses revealed that all herbicides were highly persistent with only ametryn dropping to less than half of its original concentration after 120 days. All of the other herbicides had degraded by less than 40% over that same period.

Objective 2: Determine tebuthiuron decay and off site movement in runoff water from grazing lands

-  All sites have been selected and monitoring has commenced. One of the main outcomes is a small runoff event has been sampled at the small catchment site, 100 days and 313 mm of rainfall after application. A storm of 53 mm resulted in 1.2 mm of runoff. A load of 1.19 g/ha of tebuthiuron was measured in runoff. This equates to 0.05% of the tebuthiuron applied to the whole catchment. Concentrations of tebuthiuron for individual samples were relatively consistent throughout the event, and showed no relationship with total suspended solids. It is therefore assumed that the tebuthiuron removed from the catchment was in dissolved form rather than adsorbed to soil particles.

Objective 3: Determine the average dissolved and particulate fractions for common pesticides in the Fitzroy River catchment

-  After a review of available data and current information priorities, sites and methods have been selected for wet season sampling.

-  A number of sites at various scales have been sampled during 2011/2012 wet season and 58 individual samples collected.

-  The majority of herbicides detected in samples is transported through the Fitzroy stream network is partitioned in the dissolved phase.

-  Herbicide concentrations tend to increase with higher TSS concentrations, but not at all scales.

-  There appears to be little effect on the partitioning of herbicides due to changes in catchment area.

Objective 4: Management options for pesticide use in bananas

-  A banana plot on the South Johnstone Research Station has been established to examine pesticide runoff over the 2011/12 wet season.

-  A model run (Pesticide Impact Rating Index) that incorporated all the pesticides that are used in bananas in the broader region has been performed to examine a ‘worst-case’ scenario for the industry and to help decide the pesticides of concern in the industry for analysis in this project.

Progress Update:

-    All milestones and activities specified in the Funding Deed for the project for completion prior to 31st January 2011 have been completed.

-    All site selection has been completed.

-    General ongoing to coordinate / align the projects with existing activities in NERP, Paddock to Reef, and the Reef Protection Package.

-    In addition, we have aligned the activities associated with Objective 1 (half lives in marine waters) with a related NERP project (Dr Andrew Negri, Chronic effects of pesticides) to optimise the design and maximise efficiencies between these activities.

-    The project team has contributed to several papers on pesticides about to be published, which complement the research to be undertaken in this program.

-    Senior researchers in the project team have been key participants in the formation of a pesticide working group to disseminate science knowledge back to industry groups and stakeholders.