Combined effects of biosolids application and irrigation with reclaimed wastewater on transport of pharmaceutical compounds in arable soils.

Pharmaceutical compounds (PCs) are introduced into the agricultural environment through irrigation with treated effluents and application of biosolids. Transport processes can determine the fate of PCs and the associated risks related to their exposure in the environment. The aim of this work was to evaluate the combined effects of biosolids application and irrigation with treated effluents on the mobility of PCs in soil and to elucidate the main mechanisms affecting their transport. Column-leaching experiments revealed that application of biosolids generally increased the retardation of PCs, whereas treated effluents increased the mobility of weakly acidic PCs in the biosolids-amended soils. Experiments conducted at environmentally relevant PC concentrations (≈ 1 μg/L) highlight the importance of irreversible sorption as a possible mechanism for low leachability. Data generated from this study suggest that (i) transport behavior of PCs can be affected by common biosolids application to arable land; (ii) treated effluents increase the mobility of weakly acidic PCs mainly by increasing of the soil solution pH and not due to complexation of the PCs with dissolved organic matter; and (iii) it is highly important to evaluate transport behavior at environmentally relevant concentrations and not to base modeling on data obtained from experiments conducted in high concentrations.