Chang, S. Dept of Environmental Sciences, Rutgers University,
Reinfelder, J. Dept of Environmental Sciences, Rutgers University,

Silver accumulation in aquatic organisms is primarily attributed to the bioavailability of the free Ag ion (Ag+). Some reports suggest that AgClaq is also available for biological uptake, but few studies of Ag bioavailability used the range of chloride concentrations over which AgClaq is the dominant Ag species and none used environmentally realistic, low Ag concentrations (10-200 pM). In order to assess the bioavailability of inorganic Ag species and the importance of the low polarity AgClaq complex to biological uptake, we determined the octanol-water partition coefficient of Ag over a range of chloride concentrations (0 to 50 mM) representative of fresh to brackish waters and measured short term Ag uptake rates in the euryhaline marine microalga Thalassiosira weissflogii exposed to a total silver concentration of 50 pM. Overall octanol-water partition coefficients (Dow) of inorganic silver ranged from 0.02 to 0.06. The Kow of AgClaq calculated using Dow values measured at 0.5, 5, and 50 mM Cl- and the Kow of Ag+ (0.03, measured in the absence of Cl-) was 0.09. Silver Dow and uptake rate constants in phytoplankton were highest at the Cl- concentration (5 mM) where uncharged AgClaq is the dominant (67 %) silver species. Our results demonstrate that AgClaq is the principal bioavailable species of inorganic silver in phytoplankton and suggest that direct uptake of AgClaq is important to the overall accumulation of Ag in aquatic invertebrates.
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
Code: SS28WE0264S