Persistence and partitioning of eight selected pharmaceuticals in the aquatic environment: Laboratory photolysis, biodegradation, and sorption experiments

Hiroshi Yamamoto, Yudai Nakamura, Shigemi Moriguchi, Yuki Nakamura, Yuta Honda, Ikumi Tamura, Yoshiko Hirata, Akihide Hayashi, Jun Sekizawa

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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 < 24 h), 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 > 24 h) 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 (Kd values) were much higher for three amines (atenolol, ifenprodil, and propranolol) than for neutral compounds or carboxylic acids; the Kd 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 (log Koc) showed a poor linear correlation with the octanol-water distribution coefficient (log Dow) 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.

Original languageEnglish
Pages (from-to)351-362
Number of pages12
JournalWater Research
Volume43
Issue number2
DOIs
Publication statusPublished - Feb 2009
Externally publishedYes

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Keywords

  • Biodegradation
  • Pharmaceuticals
  • Photolysis
  • Sediment
  • Sorption

ASJC Scopus subject areas

  • Ecological Modelling
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution

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