Effects of nanosilver on wetland biogeochemistry

Overview: 

Our group provided the field assessment and lab analysis of the effects of AgnPs and ionic Ag on aquatic and wetland plant species in the main mesocosm experiments being conducted by CEINT.  One outcome of the dosing was a significant uptake of silver in the aquatic species.  Elodea a floating aquatic species was a major sink for Ag in all the silver treatments.  Elodea in the Gum Arabic coated Ag (GAnAg) treatment showed the highest uptake and nearly matched the ionic silver levels after one week.  Levels dropped at the end of one month but were still significant for all Ag treatments.   The ecological effects of silver on plant growth and overall ecosystem storage are currently being compared during the final harvest of the mesocosms.  Preliminary analysis indicates a significant reduction in plant productivity, which differs by species. We conducted a separate AgNPs experiment with our controlled soil/water redox microcosm system to assess the fate and transport of AgNPs nanomaterials under controlled anaerobic/aerobic conditions. The initial dose of 2.5 mg/L of silver was found mostly in the soils compartment. Water concentrations drop by half by day four and were lowest by day 30.  The aerobic microcosm showed higher water column concentrations of Ag at the end of the experiment.  Analyses of experimental results are currently under way.