Petrographic and spectroscopic characterization of phosphate-stabilized mine tailings from Leadville,Colorado

The use of soluble PO4(3-) and lime as a heavy metal chemical stabilization agent was evaluated for mine tailings from Leadville, Colorado. The tailings are from piles associated with the Wolftone and Maid of Erin mines; ore material that was originally mined around 1900, reprocessed in the 1940s, and now requires stabilization. The dominant minerals in the tailings are galena (PbS), cerrusite (PbCO3), pyromorphite (Pb5(PO4)3Cl), plumbojarosite (Pb0.5Fe3(SO4)2(OH)6), and chalcophanites ((Pb,Fe,Zn,Mn)Mn2O5 x 2H2O). The tailings were treated with soluble PO4(3-) and lime to convert soluble heavy metals (principally Pb, Zn, Cu, Cd) into insoluble metal phosphate precipitates. The treatment process caused bulk mineralogical transformations as well as the formation of a reaction rind around the particles dominated by Ca and P. Within the mineral grains, Fe-Pb phosphosulfates, Fe-Pb sulfates (plumbojarosite), and galena convert to Fe-Ca-Pb hydroxides. The Mn-Pb hydroxides and Mn-(+/-Fe)-Pb hydroxides (chalcophanites) undergo chemical alteration throughout the grains during treatment. Bulk and surface spectroscopies showed that the insoluble reaction products in the rind are tertiary metal phosphate (e.g. (Cu,Ca2)(PO4)2) and apatite (e.g. Pb5(PO4)3Cl) family minerals. pH-dependent leaching (pH 4,6,8) showed that the treatment was able to reduce equilibrium concentrations by factors of 3 to 150 for many metals; particularly Pb2+, Zn2+, Cd2+, and Cu2+. Geochemical thermodynamic equilibrium modeling showed that apatite family and tertiary metal phosphate phases act as controlling solids for the equilibrium concentrations of Ca2+, PO4(3-) Pb2+, Zn2+, Cd2+, and Cu2+ in the leachates during pH-dependent leaching. Both end members and ideal solid solutions were seen to be controlling solids.     

Ecotoxicity of oil sludges and residuals from their washing with surfactants: soil dehydrogenase and ryegrass germination tests

Environmental Science and Pollution Research - Oil sludge washing (OSW) with surfactants and co-solvents is used to recover the oil, and this process leaves some residuals (sediments and surfactant...     

Traplining by purple-throated carib hummingbirds: behavioral responses to competition and nectar availability

We examined the effects of nectar availability and competition on foraging preferences and revisit intervals of traplining female purple-throated caribs hummingbirds (Eulampis jugularis) to Heliconia patches shared by two individuals or visited solely by one individual. Birds at both shared and solitary patches preferred multiflowered to single-flowered inflorescences, but the magnitude of this preference depended on food availability and competition. During a year of low flower availability, females visited multiflowered inflorescences more frequently than single-flowered inflorescences only when nectar availability was experimentally enhanced; similarly, females at shared patches exhibited a significant preference for multiflowered inflorescences only after experimental increases in nectar availability. Experimental manipulations of nectar availability also had different effects on revisit intervals of birds at shared vs solitary patches. Birds at shared patches responded to patch-wide increases in nectar rewards by increasing the duration of their visit intervals, whereas birds at solitary patches did not. In contrast, birds at solitary patches responded to abrupt losses of nectar at flowers (simulating competition) by decreasing the duration of their visit intervals, whereas a bird at a shared patch did not alter its return interval. The contrasting results between shared vs solitary patches suggest that future studies of traplining behavior should incorporate levels of competition into their design.     

Influence of sewage inputs and fish farm effluents on dissolved nitrogen species in a chalk river

Nitrate, ammonium and dissolved organic nitrogen (DON) concentrations were measured in the lower reaches of the River Test in Hampshire to assess the impact of two effluent point sources. An 18-month survey from July 2001 to December 2002 was carried out at locations above and below fish farm inputs and a sewage effluent outfall. The concentration of nitrate exceeded 400 μM at the four sites on all sample dates. A consistent increase in ammonium concentration was measured downstream of the fish farm, but not the sewage effluent input. DON samples collected downstream of the fish farm did not show a consistent increase in concentration, compared with the upstream sampling location, whereas the sewage effluent input at Romsey was a point source of DON to the River Test with a mean increase of 15 μM. Nitrate was the major component of dissolved nitrogen in this aquifer-fed chalk-bed river system, with up to 10% being DON and ammonium comprising <1%.     

Relocation attitudes and adjustment: A longitudinal study

This study identified correlates of attitude toward an impending employer-initiated relocation, then followed up by predicting post-transfer attitude and adjustment difficulty in the same sample. Predictors suggested by past research on mobility attitudes (i.e. demographic characteristics and attributes of the pre-move location) were less important in explaining pre-move attitude toward the transfer than were expected attributes of the new location. After the move, experienced aspects of the new location such as role ambiguity, degree of advancement, and community and job satisfaction were the strongest predictors of overall post-move attitude and adjustment difficulty. In many cases, pre-move expectations about attributes of the new location were not related to affect or adjustment after the move, suggesting that pre-move expectations may have been inaccurate. Implications for theory, research, and organizational practice are discussed.     

The Identification of Atmospheric Nitric Oxide by a Spectroscopic Scan

Lines of the 1-0 band of NO near 5.3 jum have been observed in spectra of approximately 500 m of ground-level air at Columbus, Ohio, on several occasions between October 1970 and January 1971. The estimated NO abundances lie between 0.0 and 0.08 ppm with uncertainties of ±0.01 ppm.     

A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater

A 6-month soil column experiment was conducted to compare the upward migration and plant uptake of radiochlorine and radioiodine from shallow, near-surface contaminated water tables. Both fixed and fluctuating water tables were studied. After 6 months, (36)Cl activity concentrations were relatively uniform throughout the soil profile apart from an accumulation at the soil surface, which was especially marked under a fluctuating water table scenario. In contrast, (125)I (a surrogate for (129)I) tended to accumulate at the boundary between the anoxic conditions at the base of the column and the oxic conditions above, due to its redox-dependent sorption behaviour. The uptake of (36)Cl by perennial ryegrass was much greater than that of (125)I due to its greater migration into the rooting zone and its ready availability in soil solution. In the context of radioactive waste disposal, where these radionuclides may potentially be released into groundwater, (36)Cl would be expected to present a greater potential for contamination of the biosphere than (129)I.