Abstract
Irrigation with reclaimed water and soil amendment with sewage sludge are becoming common practices in arid and semiarid areas. When wastewater treatments do not efficiently remove all the contaminants, these contaminants can later end up in agricultural soils.
These contaminated soils are a potential source of surface and groundwater pollution by leaching and runoff. In the present work, we assessed the behavior of alcohol sulfates (AS) in agricultural soil.
For the experimental work, a tract of soil was irrigated with linear alcohol sulfates with 12-18 hydrocarbon chain and subsequently tested for AS concentration from November 2014 to July 2015. The highest concentrations of AS were found at the top layer of soil (29.80 to 6.23 mg kg(-1)).
The adsorption rate and the amount of surfactant adsorbed increased as the length of the hydrocarbon chain increases. AS homologues can leach up to 60 cm.
A mathematical model was applied to predict the environmental behavior of AS in the agricultural soils studied. Disappearance rate constant (k) values for AS homologues were between -5.10 . 10(-3) and -1.68 . 10(-2) h(-1), and average half-life values were between 37 and 135 h.
Coefficients of determination (R(2)) between 92.4 and 99.1% showed that the proposed model satisfactorily describes the experimental results. The present study provides a conceptual framework and essential parameters for predicting and understanding the environmental behavior of AS in agricultural soils.