Characterization of soil organic matter by FT-IR spectroscopy and its relationship with chlorpyrifos sorption.
Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC) assuming that the main factor that influences the amount sorbed is the organic carbon content (OC) of the soil. However, KOCcan vary across a range of soils. The influence of certain soil characteristics on the chlorpyrifos KOCvalues variation for 12 representative soils of the Northpatagonian Argentinian region with different physicochemical properties was investigated for this study. The chlorpyrifos sorption coefficients normalized by the OC content were experimentally obtained using the batch equilibrium method; the KOCvalues ranged between 9000-20,000 L kg-1. The soil characteristics assessed were pH, clay content and spectral data indicative of soil organic matter (SOM) quality measured by FT-IR on the whole soil. The bands considered in the spectroscopic analyses were those corresponding to the aliphatic components, 2947-2858 cm-1(band A) and the hydrophilic components, 1647-1633 cm-1(band B). A significant relationship was found (R2= 0.66) between chlorpyrifos sorption (KOC) and the variables pH and A/B height band ratio. The correlation between the values predicted by the derived model and the experimental data was significant (r = 0.89 p < 0.05). Thus, this methodology could be used to estimate chlorpyrifos sorption coefficient through the use of a simple, rapid, and environmentally-friendly measurement. KOCanalysis in relation to soil properties represents a valuable contribution to the understanding of the attenuation phenomena of the organic contaminants off-site migration in the environment.
LIBIQUIMA, Departamento de Química, Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300, Neuquen, Argentina.
María Eugenia
ME
Parolo
LIBIQUIMA, Departamento de Química, Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300, Neuquen, Argentina.
Mónica Claudia
MC
Savini
LIBIQUIMA, Departamento de Química, Facultad de Ingeniería, Universidad Nacional del Comahue, Buenos Aires 1400, 8300, Neuquen, Argentina. Electronic address: rmloewy@gmail.com.
Ruth Miriam
RM
Loewy
D000327:Adsorption; D004390:Chlorpyrifos / Q000032:analysis*; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared
D012987:Soil; D012989:Soil Pollutants; D004390:Chlorpyrifos
FT-IR spectroscopy; Organic matter; Pesticides; Sorption