Uptake of Soil-Residual Diazinon by Rotational Lettuce under Greenhouse Conditions

Abstract

Pesticide residue is an increasing concern in rotational crop practices. The pesticide used for the primary crop may re-enter the secondary crop, thus exceeding pesticide levels set by the positive list system (PLS). As such, evaluation of pesticide residue translocated into rotational crops is required for ensuring pesticide safety. In this study, we investigated the residue pattern of diazinon translocated into lettuce as a typical rotational crop in Korea. Diazinon was used to treat greenhouse soil at the maximum annual application rate before crop planting. Diazinon residues in soil and lettuce were investigated using liquid chromatography/tandem mass spectroscopy and a modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method. The limit of quantitation (LOQ) of diazinon was found as 0.005 mg/kg for the plant and soil samples. The recovery of diazinon at the LOQ and 10× the LOQ ranged from 100.2% to 108.7%. The matrix calibration curve showed linearity, with R2 values > 0.998. Diazinon residue in soil dissipated over time after the initial treatment, generating first-order kinetics (R2 = 0.9534) and having a half-life of about 22 days. The uptake ratio (UTR) of diazinon from the soil to the plant ranged from 0.002 to 0.026 over the harvest period. Considering the UTRs, diazinon residue in the edible leaf could exceed the PLS level (0.01 mg/kg) if lettuce is rotated in soil containing >0.357 mg/kg of diazinon. Based on our findings, to comply with the PLS, a 3-month plant-back interval is required following diazinon treatment and/or setting the maximum residue limit of diazinon for lettuce.

Stable Isotope Analysis of Residual Pesticides via High Performance Liquid Chromatography and Elemental Analyzer–Isotope Ratio Mass Spectrometry

“…The residual CHL and CYN detected from plants suggest plant root uptake and transport of these pesticides, although their amounts in plants tended to decrease through the cultivation period. Similarly, the distribution of insecticides in plant parts decreased with an increased pesticide exposure period [ 1 , 25 , 26 ]. Although our study did not focus on the metabolites of CHL and CYN, there are reports that the amount of metabolites relative to the parental compound (CYN) increased [ 1 , 27 ].…”

Compound-Specific Isotope Analysis Provides Direct Evidence for Identifying the Source of Residual Pesticides Diazinon and Procymidone in the Soil–Plant System

“…The experiment, designed to assess the pesticide behavior in agricultural applications, was conducted in an agricultural greenhouse from Mar 2020 to Aug 2020 in Damyang, Jeonnam, Korea, following the methodology previously described. , In summary, the soil composition consisted of 50.4% sand, 37.6% silt, and 12% clay, with 95.08 g/kg organic matter. DIA formulation and PRO formulation (manufactured by Dongbang Agro) were purchased from a public market.…”

“…Of the two target compounds for this study (Table ), procymidone (PRO, organochlorine group) is widely used as a preventive and curative fungicide, while diazinon (DIA, organophosphate group) serves as an insecticide. The application scope, persistence, and toxicity of these target chemicals significantly differ in agricultural fields. , Both compounds are currently recorded as high residual pesticides detected in crop plants in Korea, China, and Japan. , Consequently, there is a pressing need to estimate the environmental fate of these pesticides. However, PRO and DIA of Δδ 13 C variability have not yet been systematically tested under agriculturally relevant in situ conditions.…”

“…The application scope, persistence, and toxicity of these target chemicals significantly differ in agricultural fields. 18,24 Both compounds are currently recorded as high residual pesticides detected in crop plants in Korea, China, and Japan. 18,24 Consequently, there is a pressing need to estimate the environmental fate of these pesticides.…”

“…18,24 Both compounds are currently recorded as high residual pesticides detected in crop plants in Korea, China, and Japan. 18,24 Consequently, there is a pressing need to estimate the environmental fate of these pesticides. However, PRO and DIA of Δδ 13 C variability have not yet been systematically tested under agriculturally relevant in situ conditions.…”