Pesticide behavior evaluation in organic substrates to improve the biobed-systems performance in the pesticide removal process

Abstract

Biobed systems have played a crucial role in pesticide bioremediation from agricultural effluents. Biobeds are focused on pesticide confinement, fast pesticide removal, and biodegradation. However, pesticide environmental losses have not been reported to record absolute pesticide confinement and guarantee complete pesticide degradation. Many mechanisms favor pesticide dissipation in the biobeds. Pesticide losses to the atmosphere from biobeds have not been studied. Dissipation of pesticides frequently used in the Yucatan Mexico crops (2,4-D, atrazine, carbofuran, diazinon, and glyphosate) at 41 days period was evaluated in soil and a composite boimixture (soil, sisal, corn stover, compost, and seaweed). The volatile, run-off, and remaining fraction of each biomixture component was evaluated at the microcosm level for 72 h. Pesticides were dissipated by over 98% in the biomixture at 41 days. The highest values for volatile, run-off, and remaining fraction after 72 h were observed for diazinon (~ 43% in soil), 2,4-D (~ 70% in corn stover), and glyphosate (~ 73% in soil), respectively. This behavior shows a relationship with substrate type, exposure time, and pesticide type; these factors were statistically significant (P < 0.05) on the pesticide concentrations in the studied fractions. The pH and lignin content were the factors that affected pesticide behavior in the substrates. Substrates presenting high remaining and low volatile pesticide fractions are promising for improving biobed performance in agricultural effluent treatment. It has been determined that the physicochemical properties of the substrates are important in the retention of pesticides. Proper substrate selection reduces losses by volatilization, reduces air transportation, and increases biobed efficiency.