Potential of micropollutants originated from irrigation water to contaminate soil and groundwater

Sorption oforganic contaminants insoils and sediments isacrucial factor affecting their mobility inthe vadose zone environment. Freundlich sorption isotherms were evaluated for six micropollutants identified inareas irrigated with river-water and sixteen soils. The highest Freundlich sorption coefficients, KF, were obtained for 1,3-diphenylguanidine (11.6 ± 5.0 cm3/nμg1−1/n/g) followed bytriethyl citrate (4.57 ± 4.91), 4-acetamidoantipyrine (1.43±0.24), 6 : 2 fluorinated telomer sulfonate (1.18 ± 0.42), benzo(d)thiazole-2-sulfonic acid (1.12 ± 0.33), and naphthalene-2-sulfonic acid (0.28 ± 0.17). The KFvalues for the individual compounds were correlated with soil properties. Multiple linear regressions were used toderive equations for predicting the KFvalues using the soil properties. Sorption of cationic molecules was positively affected by cation exchange capacity or clay content, indicating strong sorption of cations on negatively charged sorption sites. Sorption of anionic molecules was positively correlated with organic carbon content and wettability index, suggesting hydrophobic interactions with soil organic matter. Anion sorption was also positively influenced by magnetic susceptibility, which could indicate sorption of anions on the positively charged sorption sites. Sorption of acids was in some cases also positively affected by cation exchange capacity, which could imply their sorption via cation bridges.