Kinetic Mass Transfer Model for Contaminant Migration in Soils

This work studied the transport phenomena in the soil of the Gramacho MSW landfill located in Rio de Janeiro, Brazil. A model was proposed to determine the mass transfer rate of the leachate contaminant ions to the soil particles. Previous researchers have focused on the diffusion and sorption phenomena using simple relations that do not completely explain the data of overall mass transfer obtained by laboratory experiments. Thus, this work proposes a modified rate equation implemented into MPHMTP software that takes into account the combined mechanisms of advection and diffusion in the leachate and sorption at the particle surface followed by diffusion in the interior of the soil particle. The model predictions were compared with laboratory-measured data and presented better agreement compared to those obtained using the commercial POLLUTE software.</jats:p

Eugenol as an efficient anesthetic for neotropical fish Prochilodus nigricans (Teleostei, Prochilodontidae)

ABSTRACT The use of anesthetics in fish farming is essential to reduce stress during management. The present study proposes to evaluate the effect of eugenol as an anesthetic for the management of curimatã (Prochilodus nigricans). Fifty specimens were used (221.34±9.0 g; 25.8 ±1.1 cm), submitted to five treatments with concentrations of 0, 25, 50, 100 and 200 mgL−1 eugenol for 10 min. The times required to reach each anesthetic stage and the recovery of each fish were recorded. To check bloodglucose levels individual blood samples were taken from the fish before immersion and after ten minutes of anesthetic exposure. Evaluation of the anesthetic effect ongills was performed by histopathological analysis. The concentration of 50 mgL−1 was within the ideal limit of three minutes recommended for surgical anesthesia induction and did not significantly increase glucose levels when compared to the control group (35.7±19.4 mg dL−1), besides not causing gill injuries. At this concentration the fish presented controlled blood glucose levels within the basal levels, besides not taking the risk to have later problems concernig mortality, because this concentration ensures the good health of the gills and good recovery of the animals.</jats:p