The major source of cloud-condensation nuclei (CCN) over the oceans appears to be dimethylsulphide, which is produced by planktonic algae in sea water and oxidizes in the atmosphere to form a sulphate aerosol Because the reflectance (albedo) of clouds (and thus the Earth's radiation budget) is sensitive to CCN density, biological regulation of the climate is possible through the effects of temperature and sunlight on phytoplankton population and dimethylsulphide production. To counteract the warming due to doubling of atmospheric CO2, an approximate doubling of CCN would be needed.

Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate

http://joenschem.com/yahoo_site_admin/assets/docs/atkinson2000r.93190106.pdf

Atmospheric chemistry of VOCs and NOx

Atmospheric degradation of volatile organic compounds

A model for the photochemistry of the global troposphere constrained by observed concentrations of H2O, O3, CO, CH4, NO, NO2, and HNO3 is presented. Data for NO and NO2 are insufficient to define the global distribution of these gases but are nonetheless useful in limiting several of the more uncertain parameters of the model. Concentrations of OH, HO2, H2O2, NO, NO2, NO3, N2O5, HNO2, HO2NO2, CH3O2, CH3OOH, CH2O, and CH3CCl3 are calculated as functions of altitude, latitude, and season. Results imply that the source for nitrogen oxides in the remote troposphere is geographically dispersed and surprisingly small, less than 107 tons N yr−1. Global sources for CO and CH4 are 1.5 × 109 tons C yr−1 and 4.5 × 108 tons C yr−1, respectively. Carbon monoxide is derived from combustion of fossil fuel (15%) and oxidation of atmospheric CH4 (25%), with the balance from burning of vegetation and oxidation of biospheric hydrocarbons. Production of CO in the northern hemisphere exceeds that in the southern hemisphere by about a factor of 2. Industrial and agricultural activities provide approximately half the global source of CO. Oxidation of CO and CH4 provides sources of tropospheric O3 similar in magnitude to loss by in situ photochemistry. Observations of CH3CCl3 could offer an important check of the tropospheric model and results shown here suggest that computed concentrations of OH should be reliable within a factor of 2. A more definitive test requires better definition of release rates for CH3CCl3 and improved measurements for its distribution in the atmosphere.

/pdf/tropospheric-chemistry-a-global-perspective-29u7u1il4s.pdf

Tropospheric chemistry: A global perspective

Atmospheric mercury—An overview

Long-path FTIR spectroscopic product studies were made of mixtures containing part-per-million concentrations of O/sub 3/ and (CH/sub 3/)/sub 2/C double bonded C(CH/sub 3/)/sub 2/ (TME) in 700 Torr of O/sub 2/-N/sub 2/ to determine the formation and reactions of the dimethyl-substituted Criegee intermediate (CH/sub 3/)/sub 2/COO expected from O/sub 3/ + TME ..-->.. (CH/sub 3/)/sub 2/COO + (CH/sub 3/)/sub 2/C double bonded O. The observed stoichiometry, ..delta..-(TME)/..delta..(O/sub 3/), was typically 1.7, and among the products were CO, CO/sub 2/, HCHO, CH/sub 3/OH, CH/sub 3/OOH, CH/sub 3/C(double bonded O)OH, CH/sub 3/C(double bonded O)OOH, (CH/sub 3/)/sub 2/C double bonded O, CH/sub 3/C(double bonded O)CHO, CH/sub 3/C(double bonded O)OCH/sub 3/, CH/sub 3/C(double bonded O)CH/sub 2/(OH), and products tentatively identified as (CH/sub 2/)/sub 2/C(OH)-C(CH/sub 3/)/sub 2/OOH AND CH/sub 3/C(double bonded O)CH/sub 2/(OOH). In addition, /sup 16/O- and /sup 18/O-labeled products were identified in /sup 18/O/sub 3/-TME-air mixtures, and the effects of added HCHO, CH/sub 3/CHO, and NO/sub 2/ (or /sup 15/NO/sub 2/) on the product distribution were determined. The results indicate that ca. 25% of the (CH/sub 3/)/sub 2/COO moiety formed was thermally stable, and that the remainder largely dissociated to yield the following free radicals, i.e., (CH/sub 3/)/sub 2/COO ..-->.. CH/sub 3/C(OOH)double bondedmore » CH/sub 2/ ..-->.. CH/sub 3/C(double bonded O)CH/sub 2/ + HO. The HO-initiated oxidation of TME was shown to account for the excess consumption of TME over O/sub 3/ as well as for some of the major products observed.« less

Paul D. Maker

Papers

FTIR spectroscopic study of the mechanism for the gas-phase reaction between ozone and tetramethylethylene

An FTIR study of mechanisms for the HO radical initiated oxidation of C2H4 in the presence of NO: detection of glycolaldehyde

Fourier transform IR spectroscopic observation of pernitric acid formed via HOO + NO2 → HOONO2

Spectroscopic and kinetic studies of a new metastable species in the photooxidation of gaseous formaldehyde

Mechanism for hydroxyl radical initiated oxidation of olefin-nitric oxide mixtures in parts per million concentrations