Degradation and thermodynamic adsorption process of carbofuran and oxadicyl in a Colombian agricultural soil profile

Carbofuran and oxadixyl pesticides are used in Colombia to control pests and fungi, but their mobility through the soil profile is poorly understood. This study showed degradation and adsorption processes of these compounds in a Melanudands soil (0-100 cm) from Colombia using laboratory incubation and the batch equilibrium methods. First-order kinetic models indicated that the degradation rates of carbofuran (0.013-0.006 day-1) and oxadixyl (0.013-0.008 day-1) decreased at deeper soil layers, suggesting that the pesticides were more persistent in the sub-surface (60-100 cm) than in the surface layers (0-40 cm). The thermodynamic approach showed that the adsorption of both pesticides was similar, an exothermic and spontaneous process. The carbofuran and oxadixyl coefficient of distribution (5.8-0.3 L kg-1) and the percentage of adsorption (71.2-11.3%) were very similar in the surface layers (0-40 cm) and decreased with the soil depth. The organic carbon (OC) and clay content showed a positive correlation with the pesticide adsorption throughout the soil profile; therefore, mathematical equations were developed from multiple linear regression models for these soil properties and initial concentration. The equations were important to the estimation of the mobility of the compounds using leaching models under laboratory and field conditions

Degradation and thermodynamic adsorption process of carbofuran and oxadicyl in a Colombian agricultural soil profile

Carbofuran and oxadixyl pesticides are used in Colombia to control pests and fungi, but their mobility through the soil profile is poorly understood. This study showed degradation and adsorption processes of these compounds in a Melanudands soil (0-100 cm) from Colombia using laboratory incubation and the batch equilibrium methods. First-order kinetic models indicated that the degradation rates of carbofuran (0.013-0.006 day-1) and oxadixyl (0.013-0.008 day-1) decreased at deeper soil layers, suggesting that the pesticides were more persistent in the sub-surface (60-100 cm) than in the surface layers (0-40 cm). The thermodynamic approach showed that the adsorption of both pesticides was similar, an exothermic and spontaneous process. The carbofuran and oxadixyl coefficient of distribution (5.8-0.3 L kg-1) and the percentage of adsorption (71.2-11.3%) were very similar in the surface layers (0-40 cm) and decreased with the soil depth. The organic carbon (OC) and clay content showed a positive correlation with the pesticide adsorption throughout the soil profile; therefore, mathematical equations were developed from multiple linear regression models for these soil properties and initial concentration. The equations were important to the estimation of the mobility of the compounds using leaching models under laboratory and field conditions

Pesticide Uptake in Potatoes: Model and Field Experiments

A dynamic model for uptake of pesticides in potatoes is presented and evaluated with measurements performed within a field trial in the region of Boyaca ́, Colombia. The model takes into account the time between pesticide applications and harvest, the time between harvest and consumption, the amount of spray deposition on soil surface, mobility and degradation of pesticide in soil, diffusive uptake and persistence due to crop growth and metabolism in plant material, and loss due to food processing. Food processing steps included were cleaning, washing, storing, and cooking. Pesticide concentrations were measured periodically in soil and potato samples from the beginning of tuber formation until harvest. The model was able to predict the magnitude and temporal profile of the experimentally derived pesticide concentrations well, with all measurements falling within the 90% confidence interval. The fraction of chlorpyrifos applied on the field during plant cultivation that eventually is ingested by the consumer is on average 10-4-10-7, depending on the time between pesticide application and ingestion and the processing step considered

Evolution over Time of Ventilatory Management and Outcome of Patients with Neurologic Disease∗

OBJECTIVES: To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality. DESIGN: Secondary analysis of three prospective, observational, multicenter studies. SETTING: Cohort studies conducted in 2004, 2010, and 2016. PATIENTS: Adult patients who received mechanical ventilation for more than 12 hours. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p < 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p < 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p < 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma. CONCLUSIONS: More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease