Search

Se is an environmental concern as it can be toxic if present in high concentrations even though it is a dietary requirement for all animals. Se levels are a special concern in the Fountain Creek Watershed located in southeastern Colorado whose geological source is the Se-rich Pierre Shale. Segments of Fountain Creek have Se water levels that exceed the current EPA limit of 5 µg/l. In the studies described here, the effects of river water containing selenium were examined on fish populations at different sites along the Fountain Creek Watershed. Based on the hypothesis that high levels of Se present in the Creek and resident bryophytes should be an indicator of diversity in the river fish we explored the possibility that the low toxicity of the selenium could be due to speciation. A speciation analysis was conducted to determine the selenium(IV) and selenium(VI). Our results show that sites with higher ratios of the more toxic Se(IV) relative to total selenium exhibit lower fish diversity and number of fish. Our results indicate that factors, other than total Se, such as Se speciation may be involved in controlling the bioavailability and toxicity of this element to aquatic organisms in Fountain Creek. [ABSTRACT FROM AUTHOR]

A new dicationic ring [(water)-(ammonium)] was found as a building block for a 3D supramolecular assembly of the compound [(CH)NCHNH](NH)[VO]·8HO, 1, where (CH)NCHNH = 4-( N, N-(dimethylamino)pyridinium) (DMAP). The title compound was synthesized and characterized by single crystal X-ray diffraction at 100 K, infrared spectroscopy and thermogravimetric analysis. Compound 1 crystallizes in space group P-1 in the triclinic system with cell parameters: a = 11.1296(4) Å, b = 11.4790(4) Å, c = 11.8691(4) Å, α = 109.631(1)°, β = 100.601(1)°, γ = 92.909(1)° and R( F) = 0.021. The three-dimensional supramolecular structure is driven by intermolecular hydrogen bonds O···H-N and O···H-O from decavanadate anion with NH and [(CH)NCHNH] cations, as well as those formed between water molecules and decavanadate ions. The embedded rings consist of two sets of water-water-water-ammonium chains joint together in a twisted chair conformation, in which water-ammonium pairs are at the top and bottom sites. The ring is hydrogen bond stabilized and represents to our knowledge, the first example of building block with this composition for a supramolecular structure to be reported. [ABSTRACT FROM AUTHOR]