Dissipation of the herbicide benzofenap (Taipan 300) in a rice field ecosystem.
The fate of benzofenap [2-[4-(2,4-dicholoro-m-toluoyl)-1,3-dimethylpyrazol-5-yloxy]-4'-methylacetophenone] applied to flooded rice was studied at two locations in New South Wales (Australia). Solid-phase extraction (SPE) was compared with liquid-liquid extraction (LLE) for the determination of the commercial chemical in water samples. SPE performed well as compared to LLE (84 vs 80%) in irrigation waters. However, at the lower end of the concentration range (3 microg/L), LLE achieved higher recoveries than SPE (72 vs 59%). Rates of dissipation (DT50) from floodwaters and soils were measured. Dissipation of the herbicide from water and soil occurred fairly erratically in both mediums and can be best explained by a first-order decay process. The DT50 value for benzofenap was <1 day in irrigation water due to rapid deposition of the suspension concentrate formulation. The DT50 in surface soil was 44 days. The maximum measured concentration of benzofenap in a rice field floodwater was 39 microg/L, taking approximately 32 days to dissipate to <1 microg/L.
Quayle
Wendy C
WC
CSIRO Land and Water, PMB 3, Griffith, NSW, Australia. Wendy.Quayle@csiro.au
Oliver
Danielle P
DP
Zrna
Sharyn
S
Fattore
Alison
A
D000098:Acetophenones / Q000737:chemistry*; D017753:Ecosystem; D006540:Herbicides / Q000737:chemistry*; D009517:New South Wales; D012275:Oryza / Q000254:growth & development*; D012987:Soil / Q000032:analysis; D014867:Water / Q000737:chemistry
D000098:Acetophenones; D006540:Herbicides; D012987:Soil; D014867:Water; C403945:benzofenap