Soil column experiments used as a means to assess transport, sorption, and biodegradation of pesticides in groundwater

Abstract

Soil column experiments are used to investigate the fate of three pesticides of high, intermediate, and low solubility in groundwater: N- phosphonomethyl glycine (glyphosate); O,O-diethyl-S-[(ethylthio)methyl]phosphorodithioate (phorate); (2,4-dichlorophenoxy)acetic acid (2,4-D). Feed solutions are prepared by adding each pesticide (100 mg/L glyphosate, 50 μ g/L phorate, 50 mg/L 2,4-D) along with conservative tracer, KBr, in synthetic groundwater. The concentration of the pesticides in effluents is detected by ion chromatography (glyphosate, 2,4-D) and GC-FID (phorate). The Br⁻ breakthrough curves are employed to estimate the dispersion coefficient and mean pore velocity in each column. Solute transport and reactive models accounting for equilibrium/non-equilibrium sorption and biodegradation are coupled with inverse modeling numerical codes to estimate the kinetic parameters for all pesticides.

Keywords:

• Groundwater
• soil column
• pesticide
• dispersion
• sorption
• biodegradation
• parameter estimation

Acknowledgments

This work was performed in the course of AFYDATWSH project (title: Development of methodologies for the detection of pesticides in soil and groundwater used as tools for the risk assessment of the diffuse pollution of environment). The Project is co-funded by the European Social Fund and National Resources–(EPEAEK-II) ARCHIMIDIS.