Removal of carbofuran is not affected by co-application of chlorpyrifos in a coconut fiber/compost based biomixture after aging or pre-exposure

Biomixtures constitute the biologically active part of biopurification systems（BPS）, which are used to treat pesticide-containing wastewater. The aim of this work was to determine whether co-application of chlorpyrifos（CLP） affects the removal of carbofuran（CFN）（both insecticide/nematicides） in a coconut fiber–compost–soil biomixture（FCS biomixture）, after aging or previous exposure to CFN. Removal of CFN and two of its transformation products（3-hydroxycarbofuran and 3-ketocarbofuran） was enhanced in pre-exposed biomixtures in comparison to aged biomixtures. The co-application of CLP did not affect CFN removal, which suggests that CLP does not inhibit microbial populations in charge of CFN transformation.Contrary to the removal behavior, mineralization of radiolabeled14C-pesticides showed higher mineralization rates of CFN in aged biomixtures（with respect to freshly prepared or pre-exposed biomixtures）. In the case of CLP, mineralization was favored in freshly prepared biomixtures, which could be ascribed to high sorption during aging and microbial inhibition by CFN in pre-exposure. Regardless of removal and mineralization results, toxicological assays revealed a steep decrease in the acute toxicity of the matrix on the microcrustacean Daphnia magna（over 97%） after 8 days of treatment of individual pesticides or the mixture CFN/CLP.Results suggest that FCS biomixtures are suitable to be used in BPS for the treatment of wastewater in fields where both pesticides are employed.

Fungal contamination of stored automobile-fuels in a tropical environment

Because of the lack of reports, the base levels of microbial contamination on stored fuels are unknown in tropical regions and it is unclear whether these levels have some influence on fuel quality parameters. Therefore, fungal quality in automobile fuels stored across Costa Rican territory was evaluated during two years according to the standard ASTM D6974-04. For a total of 96 samples, counts and identification of molds and yeasts were performed on regular gas, premium gas and diesel taken from the bottom and superior part of the container tanks. The highest contamination was found on the bottom of the tanks, where an aqueous phase was usually identified, showing populations over the ones present in the hydrocarbon itself （up to 108 CFU/L）. Diesel was the most contaminated fuel （up to 107 CFO/L）; however, an alteration on the physicochemical parameters was not observed in any kind of fuel. Seventy-five mold strains were isolated, Penicillium sp. being the most common genus （45.8% of the samples）, and ten yeast strains, from the genera Candida sp. and Rhodotorula sp. Four of the yeasts were able to grow on diesel as the sole carbon source, at concentrations ranging from 0.5% to 25%. Increasing the frequency of tank cleaning, adding antimicrobial agents and monitoring microbial populations are recommended strategies to improve microbial quality of stored fuels.