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Fate of terbutryn in macrophyte‐free and macrophyte‐containing farm ponds
Author(s) -
MUIR D.C.G.,
PITZE M.,
BLOUW A.P.,
LOCKHART W.L.
Publication year - 1981
Publication title -
weed research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 74
eISSN - 1365-3180
pISSN - 0043-1737
DOI - 10.1111/j.1365-3180.1981.tb00097.x
Subject(s) - macrophyte , typha , zoology , chemistry , water column , sediment , environmental chemistry , aquatic plant , biology , ecology , wetland , paleontology
Summary: Terbutryn (2‐ethylamino‐4‐(tert‐butylamino)‐6‐methylthio‐s‐triazine) was applied in June 1978, to two farm ponds (A and C) near Winnipeg. Canada, to give 100 μg/l water concentrations. The persistence of the herbicide and its degradation products was monitored over a 61‐week period following application. The half‐life of terbutryn m the water column ranged from 3 weeks in Pond C, which contained heavy growths of cattails ( Typha sp.) and duckweed ( Lemna sp.), to 30 days in Pond A. which was free from aquatic macrophytes, Terbutryn residues m sediment reached a maximum of 1.4 μg/g (dry wt) in Pond A and 0.5 μg/g in C. Maximum concentrations of N‐deethylated terbutryn (2amino‐4‐(tert‐butylamino)‐6‐methylthio‐s‐tria‐zine)(DET) were 14.4 μg/l in Pond A water after 61 weeks and 0.14 μg/g in Pond C sediment after 30 weeks. The maximum concentration of hydroxy‐terbutryn (2‐hydroxy‐4‐ethyl‐amino‐6‐(tert‐butylamino)‐s‐triazine) (HT) observed in pond water was 6.4 μg/l in Pond C after 7 weeks. HT was not detected in sediment (<0.05 μg/g) during the study. After 61 weeks, about 50% of the terbutryn that was added could still be accounted for in Pond A and 35% in Pond C. Terbutryn. DET and HT represented an estimated 71, 28 and 1%, respectively, of total terbutryn remaining in Pond A and 65, 29 and 6%, respectively, of that remaining in Pond C, 61 weeks after application, Terbutryn residues in Typha ranged from 0.3 μg/g (dry wt) in the shoot to 3.3 μg/g in the roots. After 12 weeks, terbutryn residues in plants (Pond C) were estimated to account for 1 to 4% of the herbicide in the pond.