1996 October – 1997 August: Mt Canobolas (NSW) Atrazine experiments.

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Source: APVMA

http://apvma.gov.au/sites/default/files/atrazine-phase-6-second-draft-final-review-report.pdf

The reconsideration of approvals of the active constituent atrazine,registrations of products containing atrazine, and their associated labels.

SECOND DRAFT FINAL REVIEW REPORT Including additional assessments
Timber Plantation Trials

p53 Surface Water Monitoring for Atrazine in NSW Timber Plantations

Surface water monitoring in NSW was conducted at Canobolas in the central-west of the state near the town of Orange.

Two moderately sloping catchments on the eastern and western sides of Mt Canobolas were chosen. Ground spraying used on the first site, aerial spraying on the second site. Liquid formulations used during the first year and core-coated granules in the second year.

Atrazine concentrations were monitored at two locations. “Concentrations remained below 1 ug/L at both upstream locations in the second year… They were above the threshold in the first year for about 2 months at one station (maximum 2.9 ug/L 25 days after treatment) and about a month at the other station (maximum 20 ug/L on the morning of the fourth day after treatment, declining to 5 ug/L by the evening of the second day)… desethylatrazine (DEA) was found at the former station at concentrations up to 0.9ug/L, but only after the second day of the trial…The second rotation site was served by two monitoring stations, one at the exit of the plantation and the second 7 km downstream. Atrazine concentrations in stream water leaving the site did not exceed 1 ug/L in the first year, except for the day of treatment when 13ug/L was recorded. In the second year, a marked spike of atrazine (61ug/L) was detected in water at the first weir on the first day after treatment (20 August 1997). Concentrations remained elevated at this location for the next three months (26.5ug/L on 5 September, 4.7ug/L on 8 October, 1.2ug/L on 7 November). Residues were diluted below 0.2ug/L at the downstream monitoring station, except for a single sample in September 1997 containing 0.6ug/L. Metabolites remained undetectable in the first season, but desethylatrazine reached 1ug/L in September 1997 at the upstream station….Two flood events were sampled, 131 days after the first treatment and 15 days after the second. Peak concentrations at the high CAR station were 1.0 and 26.5 ug/L respectively…”