Sorption and Mobility of Pharmaceutical Compounds in Soil Irrigated with Reclaimed Wastewater

Irrigation with reclaimed wastewater accounts for 45% of total irrigation water in Israel. This unique situation of intensive irrigation with reclaimed wastewater and sludge application containing residues and active pharmaceutical compounds (PCs) provides an excellent opportunity to study the long-term exposure effects of these compounds in soils. The long-term introduction of PCs to arable land may affect the agro-ecosystem in various aspects which are not known to date.

In this study, the transport and sorption-desorption behaviors of carbamazepine, naproxen and diclofenac were studied in soil sampled from a citrus orchard which has been irrigated with reclaimed wastewater for more than 25 y. All the studied PCs were detected in reclaimed wastewater used for crop irrigation. Our data show that the transport of tested compounds was delayed in the 0-5 cm organic matter-rich soil layer as compared to the soil layers containing lower level of organic matter. For naproxen and diclofenac, higher mobility was observed when the compounds were introduced to the soil in treated wastewater solution as compared to freshwater. The water quality did not affect the behavior of carbamazepine. Similar to the column studies, higher sorption affinity values were observed for the organic matter-rich soil samples whereas the effect of the water quality (freshwater vs. wastewater) was less pronounced.

Our data emphasize the risks (groundwater contamination and/or uptake by plants) associated with the introduction of PCs to agro-ecosystem.