Dissolved silver in the Baltic Sea

The increased use of silver as a biocide in nanoparticle formulations has heightened concern on possible environmental implications owing to its toxicity. There is however very little data on the concentration levels of silver in marine and freshwaters. Here, I report data on dissolved (<0.4 μm filter) silver concentration in the surface waters of the Baltic Sea, the first such data reported for a European coastal water body. Levels of dissolved silver in the Baltic are comparable to those reported for other American estuarine waters and range from non-detectable in the open Baltic Sea Proper (<1 pM) to 9.4 pM (1 ng/L) in the Stockholm Archipelago, with a mean of 2.8 pM (0.2 ng/L). Inputs from wastewater treatment are clearly discernable and might constitute the main source of silver to the Stockholm Archipelago and possibly the Baltic Sea Proper.