John Wiley & Sons, Ltd.

Exceptionally strong sorption of infochemicals to activated carbon reduces their bioavailability to fish

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The addition of activated carbon (AC) to sediments is a relatively new approach to remediate contaminated sites. AC strongly sorbs hydrophobic organic contaminants, thereby reducing their bioavailability and uptake in organisms. Because of its high sorption capacity, AC might however also sorb other chemicals, which are not contaminants, but have ecological functions instead. Examples of such compounds are infochemicals or pheromones, i.e., compounds serving as chemical inter‐ and intraspecies information vectors. In the present study, we investigated the sorption of two known infochemicals, hypoxanthine‐3‐N‐oxide (H3NO) and pyridine‐N‐oxide (PNO), to five different powdered ACs. Sorption isotherms of these low molecular weight, polar fish kairomone substances appeared highly nonlinear, with logarithmic Freundlich sorption coefficients of up to 7.6. At physiologically‐relevant concentrations, sorption was up to 7 to 9 orders of magnitude stronger than expected on the basis of hydrophobic forces only (i.e., the compounds' logKow, being around ‐1), indicating exceptionally strong binding to specific sites. This binding effectively reduced the bioavailability of H3NO to Sarasa goldfish, as was shown in a behavioral assay. The present study demonstrates the previously unrecognized potential of AC to sorb ecologically‐relevant chemicals. Whether this potential may lead to subtle, unwanted ecological effects in the field will need to be investigated in more detail during future research. Environ Toxicol Chem © 2013 SETAC

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