INVESTIGADORES
GONZALEZ Mariana
congresos y reuniones científicas
Título:
Pesticides desorption from agricultural soils by organic amendements
Autor/es:
GONZALEZ, MARIANA; MIGLIORANZA, KARINA SILVIA BEATRIZ; AIZPÚN , JULIA ELENA; PEÑA, ARANZAZU
Lugar:
Marseille, Francia
Reunión:
Simposio; 11th Symposium on chemistry and fate of modern pesticides, 5th European conference on pesticides and related organic micropollutants in the environment; 2008
Resumen:
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Desorption of a-endosulfan, endosulfan sulfate, p´p´-DDT, p´p´-DDE and a-cypermethrin
from agricultural soils was assessed. Soils with different organic carbon
content, particle size distribution, and pesticides levels were taken from two
typical Argentinean productive systems. Total pesticide residues in soil were
0.63 mg g-1 dry weight for the naturally
contaminated soil and 50 mg g-1 for the artificially contaminated soil, where the five compounds were
added at an equal initial concentration. The effect of organic carboxylic acids
and synthetic surfactants on pesticides desorption from soil was evaluated
using batch experiments. Sodium citrate and sodium oxalate were used at levels
that are usually exuded by plant roots (0.05 and 0.1M), while solutions of
Sodium Dodecyl Sulfate (SDS) and Tween 80) were made at 2 and 10 times their
critical micelle concentration (CMC). Results showed that desorption of highly
hydrophobic compounds such as p´p´-DDT, p´p´-DDE and a-cypermethrin was effectively enhanced by
oxalate at the two studied concentrations. Conversely, no effect of citrate or
oxalate was observed for the hydrophilic endosulfan with respect to the control
(MilliQ water). The non-ionic surfactant Tween 80 behaved similarly to
carboxylic acids, while the anionic SDS enhanced pesticide desorption
independently of their hydrophobicity.
At the concentrations employed, desorption by surfactants was ca. 5-10 fold higher than that of
carboxylic acids. In the artificially contaminated soil the increase of Tween
80 or SDS concentration from 2 to 10 CMC led to a higher desorption rate, while
in the naturally contaminated one this was true only for SDS. Results suggest
that organic acids and surfactants could be used for soil remediation. However,
if these substances occur in irrigation waters, the solubilization of
recalcitrant compounds is feasible and leads to a new challenge to face.