title: Persistence and partitioning of eight selected pharmaceuticals in the aquatic environment: laboratory photolysis, biodegradation, and sorption experiments.
abstract: We selected eight pharmaceuticals with relatively high potential ecological risk and high consumption-namely, acetaminophen, atenolol, carbamazepine, ibuprofen, ifenprodil, indomethacin, mefenamic acid, and propranolol-and conducted laboratory experiments to examine the persistence and partitioning of these compounds in the aquatic environment. In the results of batch sunlight photolysis experiments, three out of eight pharmaceuticals-propranolol, indomethacin, and ifenprodil-were relatively easily photodegraded (i.e., half-life<24h), whereas the other five pharmaceuticals were relatively stable against sunlight. The results of batch biodegradation experiments using river water suggested relatively slow biodegradation (i.e., half-life>24h) for all eight pharmaceuticals, but the rate constant was dependent on sampling site and time. Batch sorption experiments were also conducted to determine the sorption coefficients to river sediments and a model soil sample. The determined coefficients (K(d) values) were much higher for three amines (atenolol, ifenprodil, and propranolol) than for neutral compounds or carboxylic acids; the K(d) values of the amines were comparable to those of a four-ring polycyclic aromatic hydrocarbon (PAH) pyrene. The coefficients were also higher for sediment/soil with higher organic content, and the organic carbon-based sorption coefficient (logK(oc)) showed a poor linear correlation with the octanol-water distribution coefficient (logD(ow)) at neutral pH. These results suggest other sorption mechanisms-such as electrochemical affinity, in addition to hydrophobic interaction-play an important role in sorption to sediment/soil at neutral pH.
authors.affiliation: University of Tokushima, Faculty of Integrated Arts and Sciences, 1-1, Minamijosanjima-cho, Tokushima 770-8502, Japan. hiroshi@ias.tokushima-u.ac.jp <hiroshi@ias.tokushima-u.ac.jp>
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Yudai
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Shigemi
authors.initials: S
authors.lastname: Moriguchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Yuta
authors.initials: Y
authors.lastname: Honda
authors.forename: Ikumi
authors.initials: I
authors.lastname: Tamura
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hirata
authors.forename: Akihide
authors.initials: A
authors.lastname: Hayashi
authors.forename: Jun
authors.initials: J
authors.lastname: Sekizawa
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D004777:Environment; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010782:Photolysis; D045483:Rivers; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D004364:Pharmaceutical Preparations; D014874:Water Pollutants, Chemical