Bulk Deposition of Pesticides in a Canadian City: Part 1. Glyphosate and Other Agricultural Pesticides

Abstract

Winnipeg is a city in the Canadian Prairies with a population of about 600,000. Like many other cities and towns in this region of Canada, the city is surrounded by agriculture. Weekly bulk deposition samples were collected from May to September in 2010 and 2011 and analyzed for forty-three pesticides used in Prairie agriculture. Fourteen herbicides, five herbicide metabolites, two insecticides and two fungicides were detected with 98.5% of the samples containing chemical mixtures. Glyphosate is the most widely used pesticide in Prairie agriculture and accounted for 65% of the total pesticide deposition over the two years. Seasonal glyphosate deposition was more than five times larger in 2011 (182 mm rain) than 2010 (487 mm rain), suggesting increased glyphosate particulate transport in the atmosphere during the drier year.The seasonal deposition of ten other frequently herbicides was significantly positively correlated with the amount of herbicides applied both in and around Winnipeg (r=0.90, P<0.001) and with agricultural herbicide use around Winnipeg (r=0.63, P=0.05), but not with agricultural herbicide use province wide (p=0.23). Herbicides 2,4-D, dicamba, and mecoprop had known urban applications and were more consistently detected in samples relative to bromoxynil and MCPA whose frequency of detections decreased throughout August and September. The Canadian Water Quality Guidelines for irrigation water were frequently exceeded for both dicamba (75%) and MCPA (49%) concentrations in rain. None of glyphosate concentrations in rain exceeded any of the Canadian Water Quality Guidelines established for this herbicide.

Distribution of glyphosate and aminomethylphosphonic acid (AMPA) in agricultural topsoils of the European Union

“…Therefore, the ratio should consider not only the amount applied but also the amount accumulated from previous treatments. Recent experimental and monitoring studies confirm wind-driven transport of glyphosate and AMPA (Bento et al, 2017;Farenhorst et al, 2015;Lamprea and Ruban, 2011;Quaghebeur et al, 2004). Bento et al (2017) demonstrated in a wind tunnel experiment that contents of AMPA and especially of glyphosate were particularly high (respectively N 0.6 and N 15 μg g −1 ) in the finest soil particle fractions (b 10 μm), which can be inhaled by humans directly.…”

Occurrence of glyphosate and AMPA in an agricultural watershed from the southeastern region of Argentina

“…Chang et al (2011) observed maximum glyphosate concentration of 2.5 ng/mL in rain water when rainfall follows the application period, while AMPA reached 2 ng/mL in rain water. Farenhorst et al (2015) detected Table 1 Physicochemical soil properties. Particle size distribution, % organic carbon content (OC%) and pH along the soil profile.…”

Concentrations of Herbicides in Wetlands on Organic and Minimum‐Tillage Farms

“…Since neither of these herbicides was applied to crops on organic farms, their low detection frequency in these wetlands could result from short-to long-range atmospheric transport inputs. In agreement with an atmospheric transport mechanism, Majewski et al (2014), Messing et al (2011), Chang et al (2011), and Farenhorst et al (2015 have reported glyphosate and AMPA in rain. However, because glyphosate exists as a zwitterion, it is strongly sorbed to soil and plant surfaces.…”