The origin of the inhibition can be multi-faceted, but the models in Figure and 3G clearly indicate that the NaCl reduces both the rate of mercury uptake and the amount of mercury that can be bound. The latter point is indicative of NaCl competing for or otherwise blocking binding sites. Indeed, NaCl particles could be detected directly on the sorbent. For instance, incubating the poly(S-r-limonene)-coated silica in water with 599 mM NaCl for one month resulted in substantial amounts of sodium chloride on the surface of the polymer, even after isolating by filtration and washing with water. It might also be important to consider chloride as a ligand for Hg 2+ , which may compete with sulfur in mercury binding. In any case, it is clear that the sorbent's effectiveness is reduced with increasing NaCl. This suggests that its use in remediation of seawater may not be practical or require more sorbent than for samples with lower levels of NaCl, as discussed next.