Under the Great Barrier Reef Foundation (GBRF) funded Project Bluewater 2, Farmacist Mackay has been investigating the ability of biobeds to remove herbicides and pesticides from contaminated water sourced from chemical mixing sites and spray tank wash down areas.
Farmacist has identified these sites as significant sources of point source pollution with an associated negative affect upon the quality of water entering the Great Barrier Reef Lagoon.
As a brief recap, biobeds are a form of bioreactor that contains a mixture of straw or cane trash, compost and topsoil. They operate via retaining water for a period of time allowing for the microbial breakdown of pesticides and herbicides. Currently, there are three biobed sites in operation: two on commercial sugarcane farms, Koumala and Marwood - investigating biobed capacity in a “real world” situation; and one research site at the Farmacist Mackay Sandiford office - investigating the capacity of biobeds to break down targeted chemistries.
Figure 1. Koumala commercial biobed site.
The Koumala commercial biobed site was established in March 2023 (Figure 1). Samples were taken before Biobed filtration and after Biobed filtration on both the 17th of April 2023 and 27th of June 2023.
Results
Overall results showed that for both sampling events multiple forms of pesticides were present and the biobed system was able to either substantially reduce their concentration or, in a number of cases, remove them all together. In the majority of instances, the “after” biobed filtration results for individual pesticides were below PC95 Ecotoxicity threshold values. However, across both sampling events, although substantially reduced in concentration, Imazapic and Picloram remained above PC95 values indicating a greater resistence to microbial breakdown.
As an example of the Koumala biobed filtration outcomes, results for Atrazine, Metolachlor, Diuron and Imidacloprid are provided for the 17th of April in Figures 2 to 5, and for the 27th of June in Figures 6 to 8.
THERE IS MORE TO THIS STORY!
This is an extract from the full article that was published in the Spring 2023 issue of Farmacist News. To read the full article, download the printable version using the link below: