Donglian Zhong

Pesticides in persimmons, jujubes and soil from China: Residue levels, risk assessment and relationship between fruits and soils.

Extreme and uncontrolled usage of pesticides produces a number of problems for vegetation and human health. In this study, the existence of organophosphates (OPs), organochlorines (OCs), pyrethroids (PYs) and fungicides (FUs) were investigated in persimmons/jujubes and their planted soils, which were collected from China. One OP (dimethoate), three OCs (DDT, quintozene and aldrin), six PYs (bifenthrin, fenpropathrin, cyhalothrin, cypermethrin, fenvalerate and deltamethrin) and two FUs (triadimefon and buprofezin) were found in 36.4% of persimmons and 70.8% of jujubes, with concentrations from 1.0 μg/kg to 2945.0 μg/kg. The most frequently detected pesticides in the two fruits were fenpropathrin in persimmons and cypermethrin in jujubes, with the detection frequencies of 30.0% and 22.7%, respectively. The residues of 4.5% (persimmon) and 25.0% (jujube) of samples were higher than the maximum residue limits (MRLs) of China. Compared with the fruits, more types of pesticides and higher residues were observed in their planted soils. The most frequently detected pesticides were HCH in persimmon soil and DDT in jujube soil, with the detection frequencies of 10.9% and 12.7%, respectively. For the tested samples, 39.1% of fruit samples and 63.0% of soil samples with multiple residues (containing more than two pesticides) were noted, even up to 8 residues in fruits and 14 residues in soils. Except for cyhalothrin, the other short-term risks for the tested pesticides in the fruits were below 10%, and the highest long-term risk was 14.13% for aldrin and dieldrin. There was no significant health risk for consumers via consumption of the two fruits.

Time-dependent movement and distribution of chlorpyrifos and its metabolism in bamboo forest under soil surface mulching.

The dissipation and distribution of chlorpyrifos (CHP) granule formulation in bamboo forest under soil surface mulching conditions (CP) and noncovered cultivation conditions (NCP) from soil to product were investigated. In the CP treatment, the CHP granule with slow-release effect leached from the topsoil to the subsoil. Conversely, the CHP was fixed in the topsoil (0-5 cm layer) in the NCP treatment, and no obvious leaching effect could be observed. The residue of CHP could be found in bamboo shoots from CP treatment, mainly at the bottom part (5 cm length). CHP could be degraded into 3,5,6-trichloro-2-pyridinol (TCP) in the soil and bamboo shoots. In addition, the straw used as the mulching material with higher OM and pH had some regulatory role in changing the pH and OM characteristics of the soil. Thus the straw could indirectly affect the adsorption and degradation behavior of CHP and TCP in the soil.

Environmental behaviors of phoxim with two formulations in bamboo forest under soil surface mulching.

Phoxim (emulsifiable concentrate (EC) and granules (G)) has been widely used in bamboo forests. The persistence and magnitude of phoxim residues in the crop and soil must be investigated to ensure human and environmental safety. The environmental behaviors of the two formulations were investigated in a bamboo forest under soil surface mulching conditions (CP) and non-covered cultivation conditions (NCP). The half-lives of phoxim in soil under the two conditions in soil were 4.1-6.2days (EC) and 31.5-49.5days (G), respectively. Phoxim in EC could be leached from the topsoil into the subsoil. A minimized leaching effect was observed for G under NCP. Inversely, an enhanced leaching effect was observed for G under CP. The G formulation resulted in more parent compound (in bamboo shoots) and metabolite (in soil) residues of phoxim than in the case of EC, especially under CP conditions. In addition, the intensity and duration of the formulation effect on soil pH adjustment from G were more obvious than that from EC. Results showed that the environmental behaviors (distribution, degradation, residue) of phoxim in the bamboo forest were significantly influenced by the type of formulation. The prolongation effect from phoxim G might cause persistence and long-term environmental risk. However, bamboo shoot consumption could be considered relatively safe after applying the recommended dose of the two phoxim formulations.

Simplified Determination of Organophosphorus Pesticides in Camellia Oil

ABSTRACT A rapid, simple, and economical analytical approach has been developed and evaluated for the determination of six organophosphorus pesticides in camellia oil. This method is based on dispersive liquid−liquid microextraction (DLLME) following simple extraction. Oil was extracted with methanol by a high-speed blender and filtered with glass paper to remove fat. The filtrate was incorporated in the DLLME procedure. Acetonitrile was used as the dispersive solvent and chloroform as the extraction solvent. The residues were analyzed by gas chromatography–mass spectrometry. Under the optimized conditions, the recoveries were between 78.4 and 112.8% with relative standard deviations less than 12.3%. The limits of detection for the analytes were from 0.0003 to 0.0056 mg · kg−1. The optimized method was used for the determination of organophosphorus pesticides in camellia oil.

The Fate of Organophosphorus Pesticides during Camellia Oil Production

The purpose of this study was to investigate the fate of organophosphorus pesticides (OPs) during camellia oil production process, from camellia fruit to the final oil product. The results showed that the OPs were mainly distributed in the peel of camellia fruit, basically above 40% after the pesticide application of 7 d (P < 0.05). A small amount of OPs could enter into the seed and convert to crude camellia oil, with the concentration of 19.5 to 548.2 mg/L. In addition, metabolites of OPs (25.7 to 768.9 mg/L) could be detected in the crude camellia oil. Moreover, the refining process (degumming, deacidfying, bleaching) had a significant effect on the removal of OPs from the crude camellia oil (P < 0.05), and the effect was related to the octanol-water partition constant (LogP) of pesticide. The larger the LogP, the more stable the OPs were during refining process. The final refined camellia oil was found to have no detectable levels of OPs metabolite.

Determination of Four Endogenous Phytohormones in Bamboo Shoots by Liquid Chromatography-Tandem Mass Spectrometry

A method was developed for the determination of four endogenous phytohormones,gibberellins,3-indolebutytic acid,abscisic acid and indole-3-acetic acid in bamboo shoots by liquid chromatography-tandem mass spectrometry( LC-MS / MS). The four analytes were extracted from bamboo shoots by methanol-formic acid( 99 ∶ 1,V / V),and purified by solid extraction using C18sorbent,and then analyzed by liquid chromatography-tandem mass spectrometry( LC-MS / MS). The four analytes were then separated on a reversed phase column with mobile phase containing water and methanol in a gradient elution mode. Qualitative analysis was performed using multiple-reaction monitoring( MRM). Matrix-matched calibrations were respectively used to quantify the analytes concentrations. The recoveries were in the range of 75. 2%-105. 0%,and the relative standard deviations( RSDs) were 0. 8%-11. 4% at three spiked levels of 5,50 and 200 μg / kg for all analytes. The limits of quantification( LOQ) for all analytes were between 0. 1 and 1. 0 μg / kg.