title: Sulfonylurea herbicides in an agricultural catchment basin and its adjacent wetland in the St. Lawrence River basin.
abstract: The use of sulfonylurea herbicides (SU) has increased greater than 100 times over the past 30 years in both Europe and North America. Applied at low rates, their presence, persistence and potential impacts on aquatic ecosystems remain poorly studied. During late-spring to early fall in 2009-2011, concentrations of 9 SU were assessed in two agricultural streams and their receiving wetland, an enlargement of the St. Lawrence River (Canada). Six SU in concentrations >LOQ (10 ng L(-1)) were detected in 10% or less of surface water samples. Rimsulfuron was detected each year, sulfosulfuron and nicosulfuron in two years and the others in one year only, suggesting that application of specific herbicides varied locally between years. Detection frequency and concentrations of SU were not significantly associated with total precipitation which occurred 1 to 5d before sampling. Concentrations and fate of SU differed among sites due to differences in stream dynamics and water quality characteristics. The persistence of SU in catchment basin streams reflected the dissipation effects associated with stream discharge. Maximum concentrations of some SU (223 and 148 ng L(-1)) were occasionally above the baseline level (100 ng L(-1)) for aquatic plant toxicity, implying potential toxic stress to flora in the streams. Substantially lower concentrations (max 55 ng L(-1)) of SU were noted at the downstream wetland site, likely as a result from dilution and mixing with St. Lawrence River water, and represent less toxicological risk to the wetland flora. Sporadic occurrence of SU at low concentrations in air and rain samples indicated that atmospheric deposition was not an important source of herbicides to the study area.
authors.affiliation: Environment Canada, Watershed Hydrology and Ecology Research Division, Centre Saint-Laurent, 105 McGill St., Montreal, QC H2Y 2E7, Canada.
authors.forename: Yves
authors.initials: Y
authors.lastname: de Lafontaine
authors.affiliation: Environment Canada, Watershed Hydrology and Ecology Research Division, Centre Saint-Laurent, 105 McGill St., Montreal, QC H2Y 2E7, Canada.
authors.forename: Conrad
authors.initials: C
authors.lastname: Beauvais
authors.affiliation: Agriculture and Agri-Food Canada, Science and Technology Branch, Saskatoon, SK S7N 0X2, Canada.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Cessna
authors.affiliation: Environment Canada, Watershed Hydrology and Ecology Research Division, Centre Saint-Laurent, 105 McGill St., Montreal, QC H2Y 2E7, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Gagnon
authors.affiliation: Environment Canada, Watershed Hydrology and Ecology Research Division, Centre Saint-Laurent, 105 McGill St., Montreal, QC H2Y 2E7, Canada.
authors.forename: Christiane
authors.initials: C
authors.lastname: Hudon
authors.affiliation: Environment Canada, Watershed Hydrology and Ecology Research Division, Centre Saint-Laurent, 105 McGill St., Montreal, QC H2Y 2E7, Canada.
authors.forename: Laurier
authors.initials: L
authors.lastname: Poissant
mesh_terms: D000383:Agriculture; D002170:Canada; D006540:Herbicides / Q000032:analysis*; D011725:Pyridines; D011743:Pyrimidines; D045483:Rivers; D013449:Sulfonamides; D013453:Sulfonylurea Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D006540:Herbicides; D011725:Pyridines; D011743:Pyrimidines; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D014874:Water Pollutants, Chemical; C447879:rimsulfuron; C416723:nicosulfuron; C439268:sulfosulfuron
keywords: Discharge; Precipitation; Sulfonylurea herbicides; Surface waters; Wetland