Dissolved Silver in Marine Waters: Reviewing Three Decades of Advances in Analytical Techniques and Understanding its Biogeochemical Cycling

Abstract:

Although billions of dollars have been spent over the past half-century to reduce contamination of U.S. waters, quantifying parts-per-billion reductions in surface water concentration since has been relatively unsuccessful. The reasons for the failure in identifying the benefits of these remediative efforts include: (i) historic (pre-1980) problems in accurately sampling and analyzing trace element concentrations at parts-per-billion level, so that temporal reductions in trace metal contamination reflected improved sampling and analytical accuracy rather than real decreases in those concentrations; (ii) limited seasonal and long term research.

Silver in its ionic form is more toxic to aquatic organisms than any other metal except Hg. Because Ag is not common naturally in the environment, its elevated presence in water, sediment or biological tissues is usually indicative of anthropogenic influences. However, there is very little published data on Ag levels in both water and sediment. The published studies include Ag levels in a few U.S. estuarine waters, including detailed and time series studies for the San Francisco Estuary system by the WIGS lab at UC Santa Cruz. In the open Ocean, Ag measurements are limited to a few studies in the North and South Pacific, The North and South Atlantic. However, as Gallon and Flegal recently noted, there is no available data on Ag concentrations from the Indian Ocean! Most of the dissolved Ag data from the Atlantic was made in WIGS lab at UC Santa Cruz

Analytical determination of Ag in seawater has come a long way since Murozumi reported the first dissolved Ag measurements from the N. Pacific in 1981 using isotope dilution MS after solvent extraction. In this presentation I will review analytical developments for Ag determination in the last three decades. I will also highlight the missing data gaps and present new tentative data on dissolved Ag concentration and cycling in polar regions including the Antarctic (Amundsen Sea) and The Siberian Arctic.