An Integrated Vegetated Treatment System for Mitigating Imidacloprid and Permethrin in Agricultural Irrigation Runoff

Abstract

Pyrethroid and neonicotinoid pesticides control an array of insect pests in leafy greens, but there are concerns about the off-site movement and potential water quality impacts of these chemicals. Effective on-farm management practices can eliminate aquatic toxicity and pesticides in runoff. This project evaluated an integrated vegetated treatment system (VTS), including the use of polyacrylamide (PAM), for minimizing the toxicity of imidacloprid and permethrin pesticides in runoff. The VTS incorporated a sediment trap to remove coarse particles, a grass-lined ditch with compost swales to remove suspended sediment and insecticides, and granulated activated carbon (GAC) or biochar to remove residual insecticides. Runoff was sampled throughout the VTS and analyzed for pesticide concentrations, and aquatic toxicity using the midge Chironomusdilutus and the amphipod Hyalella azteca. In simulated runoff experiments, the VTS reduced suspended sediment load by 88%, and imidacloprid and permethrin load by 97% and 99%, respectively. In runoff events from a conventionally grown lettuce field, suspended sediment load was reduced by 98%, and insecticide load by 99%. Toxicity was significantly reduced in approximately half of the simulated runoff events, and most of the lettuce runoff events. Integrated vegetated treatment systems that include components for treating soluble and hydrophobic pesticides are vital tools for reducing pesticide load and occurrence of pesticide-related toxicity.

Treating Agricultural Runoff With A Mobile Carbon Filtration Unit

“…Recent experiments with mixtures of biochar and pumice show increased ow e ciency (unpublished data), and the use of biochar and wood chip mixtures in recharge basins have demonstrated increased in ltration e ciency over biochar alone (Andrew Fisher, UC Santa Cruz, personal communication). Further study is needed to determine an optimal mixture of ow and treatment, but current studies show that if water can come in contract with the biochar, treatment will occur (Phillips et al 2021).…”

“…Research has demonstrated that combining these practices into integrated vegetative treatment systems (VTS) reduces pesticide loads and associated toxicity in agriculture tailwater runoff. Sediment basins integrated in sequence with vegetated ditches within a VTS can reduce pyrethroid pesticides up to 100% (Anderson et al 2011), and the addition of compost and granulated activated carbon to a grass-lined ditch has been shown to reduce the load of the organophosphate pesticide chlorpyrifos by up to 98% (Phillips et al 2017), and the loads of the neonicotinoid imidacloprid and the pyrethroid permethrin by 97% and 99%, respectively (Phillips et al 2021). These integrated systems have also been shown to reduce pesticide-associated toxicity to aquatic invertebrates in irrigation runoff.…”

Effectiveness of a Constructed Wetland with Carbon Filtration in Reducing Pesticides Associated with Agricultural Runoff

“…In bench-scale laboratory experiments, Voorhees et al ( 2017 ) were able to completely remove environmentally relevant concentrations of the neonicotinoid imidacloprid from simulated flows representative of agricultural runoff. Phillips et al ( 2017 , 2021 ) found the use of a vegetated ditch coupled with installations of GAC filters was effective at reducing loads of the organophosphate chlorpyrifos, as well as the neonicotinoid imidacloprid and the pyrethroid permethrin in runoff from simulated agricultural irrigation events (Phillips et al 2021 ).…”

Treating Agricultural Runoff with a Mobile Carbon Filtration Unit

“…Sediment basins integrated in sequence with vegetated ditches within a VTS can reduce pyrethroid pesticides up to 100% (Anderson et al 2011 ). The addition of compost and granulated activated carbon to a grass-lined ditch has been shown to reduce 98, 97 and 99% of the loads of the organophosphate pesticide chlorpyrifos (Phillips et al 2017 ), the neonicotinoid imidacloprid and the pyrethroid permethrin, respectively (Phillips et al 2021 ). These integrated systems have also been shown to reduce pesticide-associated toxicity to aquatic invertebrates in irrigation runoff.…”

“…Recent research has been conducted applying biochar to treat pesticides in simulated agricultural runoff (Cederlund et al 2017 ; Taha et al 2014 ; Voorhees et al 2020 ), but few studies assess the effectiveness of biochar-based water filter to reduce pesticide load and associated laboratory toxicity. Phillips et al ( 2021 ) evaluated an integrated vegetated treatment system containing either granulated activated carbon or biochar. The system was tested with both simulated irrigation runoff spiked with permethrin and imidacloprid, as well as runoff from a conventionally grown lettuce field.…”