Current use pesticides in Arctic media; 2000-2007.

This review will summarize the levels of selected current use pesticides (CUPs) that have been identified and reported in Arctic media (i.e. air, water, sediment, and biota) since the year 2000. Almost all of the 10 CUPs (chlorothalonil, chlorpyrifos, dacthal, diazinon, dicofol, lindane, methoxychlor, pentachloronitrobenzene (PCNB), pentachlorophenol, and trifluralin) examined in the review currently are, or have been, high production volume chemicals i.e. >1M lbs/y in USA or >1000 t/y globally. Characteristic travel distances for the 10 chemicals range from 55 km (methoxychlor) to 12,100 km (PCNB). Surveys and long-term monitoring studies have demonstrated the presence of 9 of the 10 CUPs included in this review in the Arctic environment. Only dicofol has not been reported. The presence of these chemicals has mainly been reported in high volume air samples and in snow from Arctic ice caps and lake catchments. There are many other CUPs registered for use which have not been determined in Arctic environments. The discovery of the CUPs currently measured in the Arctic has been mainly serendipitous, a result of analyzing some samples using the same suite of analytes as used for studies in mid-latitude locations. A more systematic approach is needed to assess whether other CUPs might be accumulating in the arctic and ultimately to assess whether their presence has any significance biologically or results in risks for human consumers.

Long-term changes in imposex frequency in file dogwinkles, Nucella lima G., and tributyltin concentrations in bay mussels, Mytilus trossulus G.

We quantified imposex in file dogwinkles (Nucella lima) and tributyltin (TBT) contamination in bay mussels (Mytilus trossulus) from a number of sites in Auke Bay, Alaska, previously studied in the late 1980s. Imposex occurrence and TBT contamination have generally declined in spatial extent and severity over time. However, high levels of TBT contamination (0.069 microg TBT/g wet tissue wt.) and imposex (100% of females affected) are still present near a large boat docking facility in the bay and deserve continued attention because of the importance of this bay to the local economy and fisheries.

Nitroaromatic reduction kinetics as a function of dominant terminal electron acceptor processes in natural sediments.

The reductive transformation of p-cyanonitrobenzene (pCNB) was investigated in laboratory batch slurries exhibiting dominant terminal electron accepting processes (TEAPs). Pseudo-first-order rate constants (k(obs)) were measured for the reduction of pCNB in nitrate-reducing, iron-reducing, sulfate-reducing, and methanogenic sediment slurries. Reduction was extremely slow in nitrate-reducing slurries but increased in slurries exhibiting TEAPs with significant concentrations of solution phase Fe(ll). As the reduction of pCNB progressed in the Fe(ll) rich systems, significant but nonstoichiometric decreases in aqueous Fe(ll) concentration were measured. Normalization of k(obs) to initial aqueous Fe(ll) concentrations (k(obs)/[Fe(ll)]t=0) gave values ranging from 0.0040 to 0.0052 d(-1) microM(-1) for nitrate-reducing, iron-reducing, and methanogenic sediment slurries as well as sulfate-reducing sediment slurries in which lactate served as a source of organic carbon. The k(obs)/ [Fe(ll)]t=0 ratios were 1-fold greater for sulfate-reducing batch slurries amended with acetate and iron-reducing slurries equilibrated with a 3% H2 atmosphere indicating that the electron source and system parameters such as pH play a determinant role in the reaction kinetics. Although these data demonstrate that aqueous phase Fe(ll) must be present for significant reduction to occur, a limited role for aqueous phase Fe(ll) as a quantitative indicator of reactivity is suggested.