Biogenic Versus Anthropogenic Sources of CO in the United States

Aircraft observations of carbon monoxide (CO) from the ICARTT campaign over the eastern United States in summer 2004 (July 1–August 15), interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem), show that the national anthropogenic emission inventory from the U.S. Environmental Protection Agency (93 Tg CO y−1) is too high by 60% in summer. Our best estimate of the CO anthropogenic source for the ICARTT period is 6.4 Tg CO, including 4.6 Tg from direct emission and 1.8 Tg CO from oxidation of anthropogenic volatile organic compounds (VOCs). The biogenic CO source for the same period from the oxidation of isoprene and other biogenic VOCs is 8.3 Tg CO, and is independently constrained by ICARTT observations of formaldehyde (HCHO). Anthropogenic emissions of CO in the U.S. have decreased to the point that they are now lower than the biogenic source in summer.Earth and Planetary SciencesEngineering and Applied Science

Evolution of Asian pollution over the Pacific Ocean : the effect of clean warm conveyor belts.

(6-11 avril 2003)

Biogenic versus anthropogenic sources of CO in the United States

Aircraft observations of carbon monoxide (CO) from the ICARTT campaign over the eastern United States in summer 2004 (July 1–August 15), interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem), show that the national anthropogenic emission inventory from the U.S. Environmental Protection Agency (93 Tg CO y−1) is too high by 60% in summer. Our best estimate of the CO anthropogenic source for the ICARTT period is 6.4 Tg CO, including 4.6 Tg from direct emission and 1.8 Tg CO from oxidation of anthropogenic volatile organic compounds (VOCs). The biogenic CO source for the same period from the oxidation of isoprene and other biogenic VOCs is 8.3 Tg CO, and is independently constrained by ICARTT observations of formaldehyde (HCHO). Anthropogenic emissions of CO in the U.S. have decreased to the point that they are now lower than the biogenic source in summer

Reactive Nitrogen over the Pacific Ocean during PEM-West A.

Measurements of NO and NOy were carried out during NASA\u27s Pacific Exploratory Mission-West A. In total, 18 aircraft flights were made over the Pacific Ocean, predominantly over the western Pacific Ocean in September and October 1991. NO and NOy were measured using a chemiluminescence instrument, and NOx was calculated from NO using a chemical box model. The measurements were carried out from 0.3 to 12 km in altitude. The NO, calculated NOx ((NOx)mc), and NOy mixing ratios in continental air were significantly higher than in maritime air. In maritime air, NO increased with altitude. The median values of NO in the boundary layer and the lower, middle, and upper troposphere were 3.7, 5.1, 11.5, and 26.6 parts per trillion by volume (pptv), respectively. In continental air, NO and (NOx)mc mixing ratios revealed a C-shaped profile. The median NO values observed in the four altitude regions were 37.8, 17.5, 18.2, and 53.2 pptv, respectively. NOy did not show any apparent altitude dependence either in maritime or in continental air. In maritime air, median NOy values in the lower, middle, and upper troposphere ranged between 211 and 226 pptv and in continental air between 382 and 401 pptv. The lowest values of NOy, PAN, and O3 were observed in tropical air masses throughout the entire altitude region. In the middle and upper troposphere of the high-latitude air masses, NO and (NOx)mc values were the lowest, although NOy mixing ratios were similar to those in continental air masses. PAN, O3, CO, CH4, and C2H6 data were used to study the budget of reactive nitrogen over the Pacific Ocean. O3 mixing ratios were found to be correlated with those of (NOx)mc, NOy, PAN, and CH4, although the degree of correlation .varied with air mass and altitude. These correlations, together with the profiles of these species, suggest that photochemical production of O3 from precursor species over the continent is important for the O3 budget in the troposphere over the western Pacific Ocean. Copyright 1996 by the American Geophysical Union

High Temporal Resolution Inverse Modeling of CO Emissions from North American Boreal Fires and Their Injection Height During the Summer of 2004

(invited)info:eu-repo/semantics/nonPublishe

Assessment of activity levels for CYP2D6*1, CYP2D6*2, and CYP2D6*41 genes by population pharmacokinetics of dextromethorphan

The pharmacokinetics of dextromethorphan (DM) is markedly influenced by cytochrome P450 2D6 (CYP2D6) enzyme polymorphisms. The aim of this study was to quantify the effects of the CYP2D6*1, *2, and *41 variants on DM metabolism in vivo and to identify other sources of pharmacokinetic variability. Concentrations of DM and dextrorphan (DO) in plasma and urine were evaluated in 36 healthy Caucasian men. These volunteers participated in three clinical studies and received a single oral dose of 30 mg DM-HBr. Data were modeled simultaneously using the population pharmacokinetics NONMEM software. A five-compartment model adequately described the data. The activity levels of the alleles assessed differed significantly. The clearance attributable to an individual CYP2D6*1 copy was 2.5-fold higher as compared with CYP2D6*2 (5,010 vs. 2,020 l/h), whereas the metabolic activity of CYP2D6*41 was very low (85 l/h). Urinary pH was confirmed as a significant covariate for DM renal clearance. These results refine genotype-based predictions of pharmacokinetics for DM and presumably for other CYP2D6 substrates as well