Selenium bioaccumulation and hazards in a fish community affected by coal fly ash effluent.
ABSTRACT Bioaccumulation of selenium (Se) in the fish community of Pigeon River/Pigeon Lake, which receives inputs of Se from a coal fly ash disposal facility, was studied to assess potential hazards of Se to fish, wildlife, and humans. Se concentrations in fish from sites receiving seepage and effluents from fly ash disposal ponds were significantly greater than those in fish from upstream, where Se concentrations were near background concentrations. Se concentrations differed among fish species, and interspecific variation was greatest at the most contaminated locations. Differences in Se bioaccumulation among fish species were not consistently associated with differences in trophic status. Although Se concentrations in northern pike were consistently less than those in likely prey species, large yellow perch contained Se concentrations as great as those in spottail shiners, their likely prey. Se bioaccumulation may have been influenced by differences in habitat preferences, as limnetic species generally contained greater Se concentrations than benthic species. Se concentrations in fish from the lower Pigeon River and Pigeon Lake did not exceed lowest observable adverse effect concentrations (LOAECs) for Se in tissues of fish species, but exceeded LOAECs for dietary Se exposure of sensitive species of birds and mammals. Human consumption of moderate quantities of fish from the areas studied should not result in excessive Se intake.
- Biophysical Journal 02/2011; 100(3). · 3.83 Impact Factor
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ABSTRACT: This paper describes the development and use of time-dependent density functional theory (TDDFT) methods for determining surface enhanced Raman scattering (SERS) spectra, with emphasis on pyridine interacting with a 20 atom silver cluster as a model of a molecule/nanoparticle system of interest to SERS. The calculations use a new implementation of a TDDFT linear response module in a locally modified version of NWChem for the TDDFT calculations. This code enables us to explore the influence of basis set effects and different choices of density functionals on the Raman spectra, including studies of correlation-consistent basis sets, and of hybrid density functionals. Previous work had employed the BP non-hybrid GGA functional, which works already quite well. Hybrid-GGA functionals such as B3LYP are better at reproducing the experimental spectra of the pyridine silver complex. However for relatively inexpensive calculations, the combination of BP with the DZVP basis set is able to provide semi-quantitative accuracy at reasonable cost, especially in conjunction with an appropriate pseudopotential for the silver atom.Computational and Theoretical Chemistry 01/2011; · 1.37 Impact Factor