Table S1: Pesticide physical-chemical characteristics of some pesticides detected in Canadian rivers

Herbicide type / Herbicide / Persistence in
surface waters / Soil sorption coefficient (Koc)1
(mL/g) / Soil half-life1
(d) / Log Kow1,2 / Water
solubility1
(mg/L)
Phenoxycarboxylic acid / Mecoprop-P3 / DT50 14 - 18 d4 / 205 / 3-13 / 0.02 (pH 7) / 860 (pH 7)
Phenoxycarboxylic acid / 2,4-D3 / DT50 12 - 13 d4 / ~ 60 / < 7 / 0.04-0.33 (pH 5) / 23,180 (pH 7)
Benzoic acid / Dicamba3 / DT50 10 - 14 d4 / 2 / < 14 / -1.88 (pH 6.8) / > 250,000 (pH 6.8)
Phenoxycarboxylic acid / Dichlorprop3 / DT50 23 - 31 d4 / 12-40 / 21-25 / < 1 (pH 7) / 350
Phenoxycarboxylic acid / MCPA3 / DT50 10 - 11 d4 / 1105 / < 7 / -0.71 (pH 7) / 294 (pH 7)
Glycine derivative / Glyphosate3,6 / DT50 2.9 - 4.8 d4 / 24,0005 / 1-130 / < -3.2 (pH 2-5) / 10,500 (pH 1.9)
Hydroxybenzonitrile / Bromoxynil7 / DT50 2.3 – 3.9 d4 / - / 75 / 1.04 (pH 7) / 89
Pyridinecarboxylic acid / Clopyralid6,7 / Hydrolysis half-life
> 30 d (pH 5-9)1 / 4.6 / 2-94 / -1.81 (pH 5) / 143,000 (pH 7)

1Data are from Tomlin (2006)

2 Kow = octanol-water partition coefficient. Log Kow is a predictor of the tendency of a chemical to bioaccumulate in aquatic organism. Chemicals with log Kow < 4 are not likely to bioaccumulate

3Herbicides are used in both crop production and urban environments

4Degenhardt et al (2011)

5Data are from Senseman (2007)

6Not detected in Canadian rivers in previous studies

7Herbicides used only for crop production (not used in urban environments) and used as surrogates for agricultural inputs of herbicides to streams in urban watersheds

References

Deganhardt D, Cessna AJ, Raina R, Farenhorst A, Pennock D (2011) Dissipation of six acid herbicides in water and sediment of two Canadian prairie wetlands. J Environ Qual. Doi:10.1002/etc.598

Senseman SA (2007) Herbicide handbook: ninth edition. Weed Science Society of America, 458 pp

Tomlin C (2006) The pesticide manual. British Crop Protection Council (BCPC), 1350 pp

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