A new concept for reduction of diffuse contamination by simultaneous application of pesticide and pesticide-degrading microorganisms

Abstract

Pesticide residues and their transformation products are frequently found in groundwater and surface waters. This study examined whether adding pesticide-degrading microorganisms simultaneously with the pesticide at application could significantly reduce diffuse contamination from pesticide use. Degradation of the phenoxyacetic acid herbicides MCPA (4-chloro-2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) was studied in soil microcosm experiments after simultaneous spraying of herbicide and herbicide-degrading bacteria on an agricultural soil and on a sand with low degradation potential. The latter represented pesticide use on non-agricultural soils poor in microbial activity. Degradation and possible loss of herbicidal effect were also tested in a system with plants and the amounts of bacteria needed to give satisfactory MCPA-degradation rate and the survival of degrading bacteria in formulated MCPA were determined. The results showed [80-99% degradation of 2,4-D and MCPA in soil within 1 day and [99% within 3 days after inoculation with 10 5 -10 7 herbicide-degrading bacteria g -1 dry weight of soil. Enhanced degradation of MCPA was also obtained in the presence of winter wheat and white mustard without loss of the intended herbicidal effect on white mustard. The survival of an isolated MCPA-degrading Sphingomonas sp. in three realistic concentrations of formulated MCPA was very poor, showing that in practical applications direct contact between the microorganisms and the pesticide formulation must be precluded. The applicability and economic feasibility of the method and the information needed to obtain a useable product for field use are discussed.

Determination and Occurrence of Phenoxyacetic Acid Herbicides and Their Transformation Products in Groundwater Using Ultra High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

“…The presence of PAC may be from the degradation of MCPA or 2,4-D [31] or PAC may be an impurity within MCPA or 2,4-D formulation products [32]. Although the degradation pathway has not been proven, it is highly likely that when MCPA or 2,4-D degrade, they will degrade to PAC (Table 1).…”

Biodegradation of Herbicide Propanil and Its Subproduct 3,4‐Dichloroaniline in Water

“…Various biological strategies can be applied for removing toxic substances, including herbicides, from the environment and are collectively known as bioremediation. Pesticide residues and their transformation products are frequently found in groundwater and surface waters 1. Irrigated rice is one of the most important crops in the state of Rio Grande do Sul, Brazil, occupying 73% of the cropland and in most farms pesticides are applied after irrigation, directly in the water 2.…”

Microbial services and their management: Recent progresses in soil bioremediation technology

“…This might have certain side effects such as a tendency to overuse the few that are allowed. A potential remedy could be that the latter chemicals are provided not as such, but accompanied with a proper microbiota to be seeded if necessary, whenever the remainder of the product has to be removed (Onneby et al, 2010). …”