Environmental fate and metabolic transformation of two non-ionic pesticides in soil: Effect of biochar, moisture, and soil sterilization.

Soil moisture, organic matter, and soil microbes are the key considering factors that control the persistence, degradation, and transformation of applied pesticides under varied soil conditions. In this study, underlying influence of these factors was assessed through the fates and metabolic transformation of two non-ionic pesticides (e.g., Phorate and Terbufos) in soils. Concisely, two distinct experiments including a customized batch equilibrium (sorption study), and a lab incubation trial (degradation study) were performed, following the OECD guidelines. As per study findings, biochar (BC) amendment was found to be the most influential factors during sorption study, particularly, 1% BC amendment contributed to achieve the best results. In addition, the non-linearity of sorption isotherm (1/n < 1.0) was revealed through Freundlich isotherm, indicating the strong adsorption of studied pesticides onto the soils. On the other hand, during degradation study, soil moisture initiates the enhanced degradation of parent pesticides and subsequent metabolism. In the presence of 40% water holding capacity (WHC), 1% BC amendment enhances the metabolic transformation, while H2O2 treatment could hinder the process. Additionally, the half-life degradation (t1/2) of phorate and terbufos was controlled by biochar amendment, moisture, and soil sterilization, respectively. Finally, BC can accelerate the metabolic transformation, whereas, phorate underwent a metabolic change into sulfoxide and sulfone while terbufos turned into solely sulfoxide. This pioneering study gathered crucial data for understanding the persistence and metabolic transition of non-ionic pesticides in soils and their patterns of degradation.

Effects of graded concentrations of supplemental selenium on selenium concentrations in tissues and prediction equations for estimating dietary selenium intake in pigs.

The experiment was conducted to determine the effects of graded dietary selenium (Se) on organ weight and Se concentrations in tissues and to develop equations for estimating dietary Se intake in pigs. Sixteen barrows (initial body weight = 30.0 ± 2.6) were allotted to four dietary treatments including graded Se supplementations with 0, 1, 5, and 50 mg/kg of diet. The experimental diets fed to the pigs for 30 d, and then the pigs were euthanized, and the organs, muscle, and urine samples were collected. The hair and blood samples of pigs were collected on d 15 and 30. Equations were developed for predicting daily Se intake using the Se concentration in plasma, hair, liver, kidneys, muscle, or urine. For graded dietary Se concentrations, linear and quadratic effects on the final body weight, weight and relative weight of liver and kidneys were not observed. The Se concentration in plasma, hair, liver, kidneys, muscle, and urine were linearly and quadratically increased as dietary Se concentration increased (P < 0.001). The dietary Se concentration was positively correlated with the Se concentrations in the plasma, organs, muscle, and urine (r > 0.81, P < 0.001). The equations for estimating dietary Se intake using the Se concentration in the plasma, hair, or organ as an independent variable were significant (P < 0.05). In conclusion, the dietary Se concentration was well reflected in the Se concentration in the plasma, hair, liver, kidneys, and urine. The Se concentration in the plasma, hair, liver, and kidneys can be used as an independent variable for estimating the Se intake.

Effects of graded concentrations of supplemental lead on lead concentrations in tissues of pigs and prediction equations for estimating dietary lead intake.

The objectives of this experiment were to determine the effects of graded dietary lead (Pb) concentrations on body weight and Pb concentrations in blood, hair, soft tissues, and urine from pigs and to generate equations for estimating daily Pb intake. Sixteen barrows with initial body weight 36.3 kg (standard deviation = 2.3) were allotted to four dietary treatments that consisted of graded supplemental Pb concentrations (0, 10, 25, and 250 mg/kg of diet). Daily feed allowances for each pig were 1 kg for first two weeks and 2 kg for last two weeks. The hair and blood of pigs were collected on d 14 and 28. At the end of experiment, the pigs were euthanized, and the liver, kidneys, muscle, and urine samples were collected. The prediction equations for estimating daily Pb intake of pigs were generated using Pb concentration of blood, hair, tissues, or urine as an independent variable. The Pb concentrations in the blood, hair, liver, kidneys, muscle, and urine linearly increased (P < 0.01) with increasing dietary Pb concentrations. There were quadratic effects (P < 0.05) of increasing dietary Pb concentration on Pb concentrations in the blood, hair, and muscle. There were highly positive correlations between dietary Pb concentration and Pb concentrations in the blood, hair, liver, kidneys, muscle, and urine (r > 0.83; P < 0.01). The equations were significant (P < 0.01) and showed high r2 (>0.83), except the equation using Pb concentration in the muscle as an independent variable. In conclusion, the dietary Pb concentration was highly correlated with Pb concentrations in the blood, hair, soft tissues, and urine of pigs. The total dietary Pb intake can be estimated from the Pb concentrations in the blood, hair, soft tissues, or urine for pigs.