Occurrence and Distribution of Carbamate Pesticides and Metalaxyl in Southern Ontario Surface Waters 2007–2010

Abstract

Surface water sampling in 2007–2010 measured the occurrence of carbamates and metalaxyl during base flow conditions and wet weather events in southern Ontario surface waters. Carbaryl, metalaxyl and pirimicarb were the most frequently detected compounds. In 2008 these three compounds were detected in over 50 % of the samples. Overall mean concentrations of carbaryl and metalaxyl over the course of the study (2007–2010) were 15 and 18 ng/L, respectively. Elevated concentrations of carbaryl (~100 to ~950 ng/L) appeared associated with wet weather (high flow) events, while highest concentrations of metalaxyl (~20–1330 ng/L) were correlated with base flow conditions. We attributed these observations as the result of runoff of carbaryl from the watershed during rain events, while metalaxyl contamination may have resulted primarily from spray drift.

Sensitivity of multiple life stages of 2 freshwater mussel species (Unionidae) to various pesticides detected in Ontario (Canada) surface waters

“…All LC x values were greater than the maximum reported Ontario surface water concentrations for these investigated pesticides (Struger et al , ; National Pesticides Monitoring and Surveillance Network ), and the results from the present study indicated that both juvenile and adult L. siliquoidea were relatively insensitive to these pesticides at subchronic exposures, especially compared to effects on other nontarget organisms including aquatic insects (e.g., Prosser et al ; Raby et al ). Similar to the V. iris glochidia, juvenile and adult L. siliquoidea would be protected by proposed water quality guidelines (Table and Figures and ; Supplemental Data, Figures S1–S14).…”

“…The present study reported the carbaryl EC50 for V. iris to be >6650 µg/L. The EC x values reported in the literature are substantially higher than concentrations for carbaryl in Ontario surface waters (Struger et al ). Lampsilis siliquoidea demonstrated a 96‐h EC50 to malathion of 23 000 µg/L (Wang et al ).…”

“…When compared to the maximum Ontario surface water concentration, the EC50 value for azoxystrobin was approximately 1668 times greater (National Pesticides Monitoring and Surveillance Network 2017; Figure 2). The ECx values for all pesticides were greater than the highest concentration measured in the surface waters of Ontario and the United States (no surface water data for flupyradifurone; Struger and Fletcher 2007;Bartlett et al 2016;Struger et al 2016Struger et al , 2017; National Pesticides Monitoring and Surveillance Network 2017; US Geological Survey 2017). Two of the 11 pesticides reported NOEC values lower than the greatest concentration tested, azoxystrobin (NOEC ¼ 186 mg/L) and carbaryl (NOEC ¼ 2380 mg/L); but they were still greater than any reported concentration in Ontario surface waters (Tables 1 and 2).…”

“… a The associated Canadian Council for the Ministers of the Environment (2007), World Health Organization (), and US Environmental Protection Agency () water quality guidelines or benchmarks are included (all concentrations are reported in micrograms per liter). Concentrations in Ontario water from the National Pesticides Monitoring and Surveillance Network (Struger and Fletcher ; Bartlett et al ; Struger et al , 2017; National Pesticides Monitoring and Surveillance Network ), and those in US water from the US Geological Survey ().…”

Synergistic Effects of Heavy Metals and Pesticides in Living Systems

“…Therefore, the organochlorines are degraded very slowly and hence remain in the environment or/and inside the organisms after exposure for longer duration (Wandiga, 2001 ). Carbamates are derived from carbamic acid and used to kill insects/pests (Struger et al, 2016 ) in a similar fashion as organophosphates. It has been shown that carbofuran is highly neurotoxic and may modulate the functions of acetylcholinesterase (AChE) (Gupta et al, 2016 ).…”