BENZENE, AROMATIC compounds, ALKYLBENZENE sulfonates, CHEMICAL reactions, ORGANIC chemistry, WATER pollution, HYDROLOGY, WASTE disposal in rivers, lakes, etc., and CLIMATE change
The methodology of solid phase microextraction (SPME) with O-(2,3,4,5,6)-pentafluorobenzylhydroxyla mine hydrochloride (PFBHA) on-fiber derivatization for the determination of carbonyls has been applied to the photo-oxidation of benzene and toluene carried out in the EUPHORE chambers. This work focuses on the results obtained for a number of highly reactive carbonyls, crucial in the determination of branching ratios and confirmation of the carbonylic route. The observed yields and kinetic behavior were compared to simulations with the Master Chemical Mechanism model, version 3.1 (MCMv3.1). The following yields were measured in the toluene system: glyoxal, (37 ± 2)%; methylglyoxal, (37 ± 2)%; 4-oxo-2-pentenal, >(13.8 ± 1.5)%; and total butenedial, (13 ± 7)% [cis-butenedial, (6 ± 3)%; trans-butenedial, (7 ± 4)%]. For benzene, the experimental glyoxal yields were (42 ± 3) and (36 ± 2)% for the two successive experiments (September 24 and 25, 2003), (17 ± 9)% for total butenedial [(8 ± 4)% cis-butenedial and (9 ± 5)% trans-butenedial (September 24, 2003)] and (15 ± 6)% total butenedial (September 25, 2003) [(7 ± 3) and (7 ± 3)% for the cis and trans isomers, respectively]. PTR-MS estimations for butenedial also allowed the two isomers of butenedial to be distinguished, but the measurements showed signs of interference from other products. The results presented confirm the fast ring cleavage and provide further experimental confirmation of the dicarbonylic route. [ABSTRACT FROM AUTHOR]
EMISSIONS (Air pollution), AIR pollution, EMISSIONS trading, AIR pollution monitoring, ORGANIC chemistry, WATER pollution, HYDROLOGY, WASTE disposal in rivers, lakes, etc., and CLIMATE change
Impact of climate change alone and in combination with currently planned emission control strategies are investigated to quantify effectiveness in decreasing regional ozone and PM2.5 over the continental U.S. using MM5, SMOKE, and CMAQ with DDM-3D. Sensitivities of ozone and PM2.5 formation to precursor emissions are found to change only slightly in response to climate change. In many cases, mass per ton sensitivities to NOx and SO2 controls are predicted to be greater in the future due to both the lower emissions as well as climate, suggesting that current control strategies based on reducing such emissions will continue to be effective in decreasing ground-level ozone and PM2.5 concentrations. SO2 emission controls are predicted to be most beneficial for decreasing summertime PM2.5 levels, whereas controls of NOx emissions are effective in winter. Spatial distributions of sensitivities are also found to be only slightly affected assuming no changes in land-use. Contributions of biogenic VOC emissions to PM2.5 formation are simulated to be more important in the future because of higher temperatures, higher biogenic emissions, and lower anthropogenic NOx and SO2 emissions. [ABSTRACT FROM AUTHOR]
ORGANIC chemistry, WATER pollution, HYDROLOGIC cycle, HYDROLOGY, WATER utilities, PHYSICAL organic chemistry, WATER quality, WASTE disposal in rivers, lakes, etc., and CALCITE
Biofilms of sulfate-reducing bacteria Desulfovibrio desulfuricans G20 were used to reduce dissolved U(VI)and subsequently immobilize U(IV) in the presence of uranium-complexing carbonates. The biofilms were grown in three identically operated fixed bed reactors, filled with three types of minerals: one noncarbonate-bearing mineral (hematite) and two carbonate-bearing minerals (calcite and dolomite). The source of carbonates in the reactors filled with calcite and dolomite were the minerals, while in the reactor filled with hematite it was a 10 mM carbonate buffer, pH 7.2, which we added to the growth medium. Our five-month study demonstrated that the sulfate-reducing biofilms grown in all reactors were able to immobilize/reduce uranium efficiently, despite the presence of uranium-complexing carbonates. [ABSTRACT FROM AUTHOR]
ORGANIC chemistry, BIOPOLYMERS, BIOMOLECULES, WATER pollution, HYDROLOGIC cycle, HYDROLOGY, WATER utilities, PHYSICAL organic chemistry, WATER quality, and WASTE disposal in rivers, lakes, etc.
Sorption of phenanthrene and naphthalene by chitin and cellulose, as well as these biopolymer-derived chars, was examined. Carbon contents were much higher in the chars than their respective biopolymers, and nitrogen was dramatically accumulated in the chitin-derived chars. After charring, sorption Of these two compounds was greatly increased, which was attributed to the newly created surface area, porosity, and aromatic components. The aromatic carbon content of the biopolymer chars increased with an increase in the charring temperature. Sorption of phenanthrene and naphthalene to chitin and cellulose was dominated by partitioning. However, after charring, sorption of these two compounds became much more of an adsorption process, because of the newly created surfaces and micropores. The maximum mass sorption capacity of phenanthrene and naphthalene by the original biopolymers and their chars was positively correlated with their surface areas, suggesting that active sorption sites were largely on the surfaces of chars. At low solute concentrations, sorption of phenanthrene and naphthalene by biopolymer chars was dominated by the micropore-filling mechanism; with an increase in the solute concentration, sorption of these two compounds by biopolymer chars shifted to a surface-sorption-dominant process. The maximum mass sorption capacity and Kow-normalized sorption amount of phenanthrene were lower than those of naphthalene by the biopolymers and their chars, showing the influence of molecular dimension on sorption. This study demonstrates the significantly enhanced sorption of hydrophobic organic compounds by highly polar biopolymers through charring and the joint roles of surface area, porosity, and surface functionalities of biopolymer-derived chars in governing sorption. [ABSTRACT FROM AUTHOR]