Pesticide distribution in an agricultural environment in Argentina.

An assessment of the off-site migration of pesticides from agricultural activity into the environment in the Neuquen River Valley was performed. The aim of this study was to evaluate the distribution of pesticides in several compartments of a small agricultural sub-catchment. Soil, surface water, shallow groundwater and drift deposition were analyzed for pesticide residues. Results showed the presence of some pesticide residues in soil, surface water and shallow groundwater compartments. The highest detection frequencies in water (surface and subsurface) were found for azinphos-methyl and chlorpyrifos (>70%). In terms of concentration, the highest levels were observed in shallow groundwater for azinphos methyl (22.5 µg/L) and carbaryl (45.7 µg/L). In the soil, even before the application period had started, accumulation of residues was present. These residues increased during the period studied. Spray drift during pesticide application was found to be a significant pathway for the migration of pesticide residues in surface water, while leaching and preferential flows were the main transport routes contributing to subsurface contamination.

Production of volatile phenols by Pichia manshurica and Pichia membranifaciens isolated from spoiled wines and cellar environment in Patagonia.

In order to detect spoilage yeast species in wines showing off-odors, different yeast isolation protocols were evaluated. Independently of the isolation method, only Saccharomyces cerevisiae and Pichia manshurica were detected. The spoilage capacity of P. manshurica regional isolates was evaluated in red wine and the production of volatile phenols was evidenced. To evaluate the possible source of contamination, yeasts from both grapes and cellar surfaces were obtained. Hanseniaspora uvarum and Zygoascus hellenicus were detected in both sound and damaged grapes from sunny areas. The most frequent species in cellar surfaces was Candida boidinii, Pichia membranifaciens and P. manshurica were detected in filters. The intra-specific genetic characterization of the P. manshurica isolates by mtDNA-RFLP demonstrated that the same strain was detected in both wine and filter. Most P. membranifaciens isolates produced 4-EP (maximum level of 1.895 mg/L) and particularly high levels of 4-EG (maximum level of 10.260 mg/L) were produced by P. manshurica isolates in synthetic wine-like medium. In this work the capacity of P. manshurica and P. membranifaciens species to produce volatile phenols was shown for the first time.