2008/9: A range of pesticides were detected in time-integrated passive samplers deployed in inshore marine waters in the Wet Tropics region over the 12-month monitoring period. Detected pesticides included diuron, atrazine, hexazinone, simazine and tebuthiuron. Concentrations of detected pesticides were typically higher during the wet season, and the maximum water concentrations of individual herbicides ranged from 2 to 15 nanograms per litre.
In high river flow conditions, a similar range of pesticides were detected off the Tully and Murray Rivers in 2008 but not above Great Barrier Reef Marine Park Water Quality Guidelines. However, concentrations of diuron did exceed 100 nanograms per litre (Lewis et al., 2009), which is above the effects level for photosynthesis inhibition in a number of marine plants.