1998-1999: Toolara (Qld). Pesticide: Simazine

Simazine concentrations in soil groundwater and stream water following application to Pinus plantations in the coastal lowland forests of south-east Queensland. K.A.Bubb Queensland Forestry Research Institute. October 2000

“…The study had two components, the first being a large-scale catchment study site (903 ha) which assessed the level of simazine residues being transported from the point of application to the shallow unconfined aquifer and the major drainage stream over a 13-month period. The second component consisted of a seperate study on a small-scale study site (0.1 ha) to assess simazine persistence and its potential to leach in the course textured and relatively infertile soils of the area.

… Simazine was regularly detected in streamwater after surface runoff events but was below the current Australian drinking water health value. The detection of simazine in the unconfined aquifers at both sites indicated that it has the potential to leach to groundwater. However,  under routine applications it would seem that the groundwater concentrations were low and short lived (persistence < 6 weeks). The results indicated that simazine has a relatively short half-life (mean 13 days) in the course textured soils of the coastal lowlands of south-east Queensland…”

Mean simazine residues in perched aquifer at the small-scale study site following application 3 (25th March 1999)

<2 to 0.7ug/L. 0.6 to 0.7ug/L 14-21 days after treatment at groundwater depths between 0.43 and 0.7m

Mean Simazine residues (kg ha in soil following application) up to 96 days at one site.