Pervasive Pesticide Contamination of Wetlands in the Great Barrier Reef Catchment Area

Abstract

Knowledge of the types and impacts of contaminants occurring in the freshwater wetlands of the Great Barrier Reef catchment area (GBRCA) is limited. The present study examined the presence and concentrations of pesticides occurring in 22 floodplain wetlands, situated in moderate to high-intensity land uses in the GBRCA. The dominant land use within 1 km of the wetlands was sugar cane for 12 wetlands, grazing for 6 wetlands, plantation forestry and conservation for 2 wetlands, and one with an equal mix of land uses. Fifty-nine pesticides and pesticide degradates were detected in the wetlands during 2 consecutive early wet seasons. These included 27 herbicides, 11 herbicide degradates, 11 insecticides, 8 fungicides, 1 nematicide, and 1 pesticide synergist. Each wetland sampled contained between 12 and 30 pesticides with an average of 21 pesticides detected per wetland sampling. Temporal differences existed in the number, types, and average concentrations of pesticides detected. No exceedances of Australian and New Zealand water guideline values were found during the first sampling season, while 10 wetlands had concentrations of at least 1 pesticide exceeding the guidelines during the following sampling season. For 1 wetland, concentrations of 4 pesticides were greater than the prescribed guideline values. Individually, the vast majority of aquatic species would be protected, but in some wetlands, diuron would affect 49% of species and atrazine up to 24% of species. Statistically significant correlations between the number of pesticides and the percentage of intensive land use, primarily sugar cane growing in a 1 km radius of the wetlands, were found. Integr Environ Assess Manag 2020;16:968-982.

Potential Pollution Sources from Agricultural Activities on Tropical Forested Floodplain Wetlands Revealed by Soil eDNA

“…For instance, pesticides can change the reproduction fitness of barramundi [14], and fertilisers can cause weed proliferation [15]. Currently, the assessment and monitoring of pollution in wetlands of the Great Barrier Reef catchments has been conducted through intensive temporal and spatial sampling [16,17] or the evaluation of the use of fertilisers and pesticides [12]. In these and other catchments with intense agricultural land-use, identifying the sources of contaminants at the species level could complement these efforts and be particularly useful to identify sources that are not necessarily close by.…”

Estimating the Aquatic Risk from Exposure to Up to Twenty-Two Pesticide Active Ingredients in Waterways Discharging to the Great Barrier Reef

“…Both Warne et al (2020) and Spilsbury et al (2020) reported >80 % of samples from monitored GBR waterways contained PAI mixtures. Similarly, Vandergragt et al (2020) found that all of the 22 monitored wetlands in the GBR catchment area contained between 12 and 30 PAIs at each sampling period. To protect the GBR from the harmful effects of PAIs and other aquatic pollutants (i.e., suspended solids (eroded soil), and nutrients (nitrogen and phosphorus)) the Australian and Queensland governments have developed the Reef 2050 Water Quality Improvement Plan (Reef 2050 WQIP) (Australian Government and Queensland Government, 2018).…”

The potential for applying “Nonviolent Communication” in conservation science

“…Another common source of conflict surrounds the negative effects of chemical run-off on surrounding ecosystems (Packer, 2019). Although the negative effects of chemical run-off on the environment (and on people) is increasingly well known, pesticide and herbicide application (often above recommended limits) is frequently applied to areas close to important natural ecosystems (Edge et al, 2020;Vandergragt, Warne, Borschmann, & Johns, 2020). We highlight this in Table 1 with an example of someone applying herbicide close to a national park.…”