Photoassisted bleaching of dyes utilizing TiO2 and visible light

Titanium dioxide was shown to be generally effective as a catalyst for photobleaching many structural classes of organic dyes in aqueous solution, using visible light. However, results from study of 15 dyes indicate that photobleaching rates differ significantly from families of dyes with different functionalities, and are dependent on the light source and crystalline form of TiO2 used. Sorption characteristic on the TiO2 surface and the aqueous solubility of the dyes also play an important role in the photobleaching rate. Kinetic analysis indicates that the dye photobleaching rates can usually be approximated as pseudo-first-order kinetics. In addition to the generally proposed photocatalytic oxidation mechanism for TiO2 reactions, we observed evidence for two kinds of electron transfer mechanisms that are "photosensitized reduction" and "photosensitized oxidation". Natural sunlight was effectively used to photobleach some of the dyes.     

Heterotrophic community-level physiological profiles of domestic wastewater following treatment by small constructed subsurface flow wetlands.

Seasonal treatment performance of small-surface flow wetlands was evaluated during their second operational year and compared with community-level physiological profiles (CLPP) of the heterotrophic bacterial community obtained from sole-carbon source utilization patterns in BIOLOG GN (Haywood, California) microplates. The CLPP patterns varied significantly by season, indicating reduced functional diversity in the heterotrophic community during warmer months of active plant growth (April through October). Principal component analysis (PCA) suggested that the functional community differed in planted versus unplanted wetlands during the growing season. Wetlands generally improved wastewater quality; however, treatment performance was reduced in the second year. Despite differences in the heterotrophic community suggested by CLPP, treatment efficiency with respect to removal of five-day biochemical oxygen demand or reduction in fecal indicator organisms generally was not significantly changed as a function of growing season or plant treatment.     

Enhancement of PAH biomineralization rates by cyclodextrins under Fe(III)-reducing conditions

Amendment of a soil slurry with low concentrations of a cyclodextrin, hydroxypropyl-beta-cyclodextrin (HPCD), (0.05-0.5 g l(-1)) increased the phenanthrene mineralization rate of a microbial consortium by 25% under Fe(III)-reducing conditions. Although a higher concentration (5.0 g l(-1)) resulted in a faster initial rate of mineralization, mineralization ceased after 25 days with maximum mineralization 17% lower than the control (no HPCD). At lower HPCD concentrations, mineralization was still taking place at day 76. Although pH should affect Fe(III) solubility, mineralization rates at pH 6.0 and 8.0 were comparable. Decreasing the temperature reduced the extent and rate of mineralization, but mineralization rates at 10 degrees C were still 60% of that obtained at 30 degrees C.     

Source apportionment of Phoenix PM2.5 aerosol with the Unmix receptor model

The multivariate receptor model Unmix has been used to analyze a 3-yr PM2.5 ambient aerosol data set collected in Phoenix, AZ, beginning in 1995. The analysis generated source profiles and overall average percentage source contribution estimates (SCEs) for five source categories:gasoline engines (33 +/- 4%), diesel engines (16 +/- 2%), secondary SO4(2-) (19 +/- 2%), crustal/soil (22 +/- 2%), and vegetative burning (10 +/- 2%). The Unmix analysis was supplemented with scanning electron microscopy (SEM) of a limited number of filter samples for information on possible additional low-strength sources. Except for the diesel engine source category, the Unmix SCEs were generally consistent with an earlier multivariate receptor analysis of essentially the same data using the Positive Matrix Factorization (PMF) model. This article provides the first demonstration for an urban area of the capability of the Unmix receptor model.     

Polycyclic aromatic hydrocarbons storage by Fusarium solani in intracellular lipid vesicles

Accumulation and elimination of polycyclic aromatic hydrocarbons (PAHs) were studied in the fungus Fusarium solani. When the fungus was grown on a synthetic medium containing benzo[a]pyrene, hyphae of F. solani contained numerous lipid vesicles which could be stained by the lipid-specific dyes: Sudan III and Rhodamine B. The fluorescence produced by Rhodamine B and PAH benzo[a]pyrene were at the same locations in the fungal hyphae, indicating that F. solani stored PAH in pre-existing lipid vesicles. A passive temperature-independent process is involved in the benzo[a]pyrene uptake and storage. Sodium azide, a cytochrome c oxidation inhibitor, and the two cytoskeleton inhibitors colchicine and cytochalasin did not prevent the transport and accumulation of PAH in lipid vesicles of F. solani hyphae. F. solani degraded a large range of PAHs at different rates. PAH intracellular storage in lipid vesicles was not necessarily accompanied by degradation and was common to numerous other fungi.     

EFFECTS OF IMPROVED PRECIPITATION ESTIMATES ON AUTOMATED RUNOFF MAPPING: EASTERN UNITED STATES1

ABSTRACT: We evaluated maps of runoff created by means of two automated procedures. We implemented each procedure using precipitation estimates of both 5-km and 10-km resolution from PRISM (Parameter-elevation Regressions on Independent Slopes Model). Our goal was to determine if using the 5-km PRISM estimates would improve map accuracy. Visual inspection showed good general agreement among our runoff maps, as well as between our maps and one produced using a manual method. A quantitative uncertainty analysis comparing runoff interpolated from our maps with gage data that had been withheld showed slightly smaller actual and percentage interpolation errors for the 5-km PRISM-based maps. Our analyses suggest a modest region-wide improvement in runoff map accuracy with the use of PRISM-based precipitation estimates of 5-km (compared to 10-km) resolution.     

Multiple paternity in wild populations of the garter snake,Thamnophis sirtalis

Summary Many adaptations have arisen in response to spern competition. In garter snakes, males produce copulatory plugs that are thought to prevent such competition. We tested this assumption using paternity exclusion techniques with electrophoretic data from 32 litters of snakes collected from two populations. Multiple paternity was confirmed in 50% of the litters examined (13/22 Michigan litters; 3/10 Wisconsin litters), and we estimate that as many as 72% of the litters may have been multiply sired. The presence of multiple paternity was also confirmed using the technique of genotypic regression. Mean relatedness in litters with evidence of multiple paternity was 0.390±0.053; in litters lacking such evidence mean relatedness was 0.498±0.022. Thus our data reveal a high incidence of multiple paternity in these snakes and suggest that their adaptations to prevent sperm competition are surprisingly ineffective.