Accumulation of cadmium in periphyton was investigated under field conditions while Cd concentration and speciation were dynamically varying in a small stream during rain events. Speciation in water was determined in situ by diffusion gradient in thin-films (DGT) and by modeling of complexation with fulvic acids. During the rain events, dissolved Cd concentrations increased from 0.17 nM to 0.27–0.36 nM, and 70–97% were DGT-labile. Cd content in periphyton closely followed Cd concentrations in water, despite higher concentrations of Zn and Mn, and may be controlled by either free or DGT-labile Cd concentrations. Decrease of Cd content in periphyton after the rain events was slower than the decrease of Cd concentration in water. Concentrations of Zn, Mn, Cu, Pb and Fe in periphyton also followed the dynamic variations of metal concentrations in water. Repeated exposure of periphyton to elevated dissolved Cd may lead to Cd accumulation. Cadmium accumulation in periphyton was examined in a small stream during rain events in relation to Cd speciation.

In streams, periphyton biofilms are important sinks for trace metals such as cadmium and are primary food sources of many invertebrate consumers. To study Cd trophic transfer, we produced differentially contaminated diets by exposing natural periphyton to environmentally relevant dissolved Cd ranging from 0 to 10 μg L−1 for 6–7 days using a radiotracer approach. On average, periphyton grown during three different seasons bioconcentrated Cd similarly – approximately 1315 (±442) -fold above dissolved concentrations. However, mayfly larvae (Centroptilum triangulifer) raised on these differentially contaminated diets (first instar through adulthood) had significantly higher trophic transfer factors from periphyton grown in Aug and Nov 2008 (4.30 ± 1.55) than from periphyton grown in Jan 2009 (0.85 ± 0.21). This Cd bioaccumulation difference is only partially explained by apparent food quality and subsequent growth differences. Taken together, these results suggest that primary producers at the base of food webs drive metal bioaccumulation by invertebrate grazers. Periphyton is a major source of Cd bioaccumulation in a grazing mayfly.

Leachates of anti-fouling paints for use on ships and leisure boats are examined for their ecotoxicological potential. Paint leachates were produced in both 7‰ artificial (ASW) and natural seawater (NSW) and tested on three organisms, the bacterium Vibrio fischeri, the macroalga Ceramium tenuicorne, and the crustacean Nitocra spinipes. Generally, leaching in ASW produced a more toxic leachate and was up to 12 times more toxic to the organisms than was the corresponding NSW leachate. The toxicity could be explained by elevated concentrations of Cu and Zn in the ASW leachates. Of the NSW leachates, those from the ship paints were more toxic than those from leisure boat paints. The most toxic paint was the biocide-free leisure boat paint Micron Eco. This implies that substances other than added active agents (biocides) were responsible for the observed toxicity, which would not have been discovered without the use of biological tests. Leachate from a biocide-free anti-fouling paint for leisure boat use was more toxic than leachates from ship paints.

Soil, sediment, water, and biota collected from the western coast of Korea were analyzed to determine occurrence and sources of perfluorinated compounds (PFCs). PFCs were significantly concentrations of PFCs were measured in some water and biological samples, while concentrations of PFCs in soils and sediments were relatively low. The most widely detected compound was found to be perfluorooctanesulfonate (PFOS), with a maximum concentration in water of 450 ng/L and in fish of 612 ng/g, dw. PFOS concentrations in water and biota were both less than those thought to cause toxicity. However, in both cases concentrations were within a factor of 10 of the toxicity threshold concentration. Concentrations of PFCs were significantly greater downstream than those upstream on the same river, suggesting point sources. Overall, the detection of PFCs at relatively great concentrations in various environmental matrixes from this region of Korea suggests that further studies characterizing PFCs and their potential risk to both humans and wildlife are needed.