The Occurrence of Carbamazepine in Wastewater Irrigated Soils: Effects of Land Use.

The anti-epileptic drug, Carbamazepine, is one of the more persistent pharmaceutically active compounds found in wastewater effluent, due to its resilience to many treatment processes.  In addition, laboratory studies have found that carbamazepine has a strong affinity to bind to the soil.  Wastewater irrigation is an alternative to stream discharge of wastewater effluent, which utilizes the soil as a tertiary filter to remove excess nutrients and has the potential to remove pharmaceutical compounds.  The objectives of our research were to characterize the occurrence of carbamazepine in soils that have been receiving wastewater irrigation for over 25 years under three different land uses: cropped, grassed and forested.  Wastewater irrigation at The Pennsylvania State University has been in full scale operation since the early 1980’s.   The facility is permitted to add two inches of wastewater per week, throughout the year.  Triplicate soil cores were collected at each of the land uses to a depth of 48 inches.   The cores were sampled at depths of 0, 3, 6, 12, 24 and 48 inches.  Extractions for carbamazepine were performed using 5 gram soil samples and 20 mL of acetonitrile.  The extracted solutions were analyzed on a LC/MS/MS.  The samples were also analyzed for supporting information such as organic carbon, pH, EC and a variety of metals.  Wastewater effluent samples were also analyzed for carbamazepine, using a solid phase extraction procedure.  Results suggest that there is accumulation of the carbamazepine in the surface soils, which have the highest organic carbon content.  Average concentrations of carbamazepine in the surface soils were 4.9, 2.9, and 1.9 ng/gm,  for the forested, grassed and cropped land uses, respectively.   The majority of the carbamazepine was found in the upper 12 inches of the profile.  Our results suggest that the soils do adsorb carbamazepine at the field scale and may provide additional renovation to the wastewater.