Methyl halides in and over the eastern Pacific (40 /sup 0/N-32 /sup 0/S)

Journal Article · Wed Apr 20 04:00:00 EST 1983 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JC088iC06p03684· OSTI ID:5982618

Singh, H B; Salas, L J; Stiles, R E

Methyl chloride, methyl bromide, and methyl iodide measurements in and over the eastern Pacific (40 /sup 0/N and 32 /sup 0/S latitude) show mean air concentrations of 633 parts per trillion (ppt), 23 ppt, and 2 ppt, and mean surface seawater concentrations of 11.5 ng/l, 1.2 ng/l, and 1.6 ng/l respectively. Long-term ambient measurements at a marine Pacific site (39 /sup 0/N) show an essentially unchanging background, with some indication of high concentrations of methyl bromide and methyl iodide during summertime. The oceanic data indicate a mean surface supersaturation of 275%, 250%, and 340%, respectively, for these three methyl halides. Depth profiles show that methyl halides are most abundant in the top mixed layer of the ocean. Oceanic concentrations of methyl chloride and methyl bromide are significantly correlated (linear regression coefficient of 0.85), suggesting a common source. No relationship between oceanic methyl iodide concentrations and the other two halides could be found. Coexistence of high concentrations of methyl iodide with relatively low concentrations of methyl chloride and vice versa provided no direct support for the hypothesis that chloride ion reactions with methyl iodide may be the dominant oceanic source of methyl chloride. For the eastern Pacific, mean ocean to air fluxes (in units of 10/sup -7/ g cm/sup -2/ yr/sup -1/) of 13,1, and 1 are determined for methyl chloride, methyl bromine, and methyl iodide, respectively. When extrapolated to global waters, they provide an adequate source to explain the atmospheric reservoir of these organic halides. Total organic bromine and iodine measurements would suggest that methyl bromide and methyl iodide contribute predominately to the tropospheric bromine and iodine organic reservoir.

• Research Organization: Atmospheric Science Center, SRI International, Menlo Park, California 94025
• OSTI ID: 5982618
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 88:C6; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ABUNDANCE
AIR
AIR-WATER INTERACTIONS
BROMINATED ALIPHATIC HYDROCARBONS
CHEMICAL COMPOSITION
CHEMISTRY
CHLORINATED ALIPHATIC HYDROCARBONS
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
FLUIDS
GASES
GEOGRAPHICAL VARIATIONS
HALOGENATED ALIPHATIC HYDROCARBONS
IODINATED ALIPHATIC HYDROCARBONS
LATITUDE EFFECT
METHYL BROMIDE
METHYL CHLORIDE
METHYL IODIDE
ORGANIC BROMINE COMPOUNDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PACIFIC OCEAN
SEAS
SURFACE AIR
SURFACE WATERS
TROPOSPHERE
VARIATIONS
WATER CHEMISTRY