Natural methyl bromide and methyl chloride emissions from coastal salt marshes

• Published in: Nature (London) Vol. 403; no. 6767; pp. 292 - 295
• Main Authors: Rhew, Robert C, Miller, Benjamin R, Weiss, Ray F
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 20.01.2000; Nature Publishing Group
• Subjects: Animal, plant and microbial ecology; Anthropogenic factors; Applied ecology; Applied sciences; Atmosphere - chemistry; Atmospheric pollution; Biological and medical sciences; Biomass; Brackish; California; Circadian Rhythm; Coasts; Dispersed sources and other; Ecosystem; Ecotoxicology, biological effects of pollution; Emissions; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrocarbons, Brominated - analysis; Hydrocarbons, Brominated - metabolism; Hydroxyl radicals; Marine; methyl bromide; methyl chloride; Methyl Chloride - analysis; Methyl Chloride - metabolism; Natural gas; Oceanography; Oxidation; Ozone; Ozone depletion; Pollution; Pollution sources. Measurement results; Salt marshes; Seasons; Soil; Terrestrial environment, soil, air; Terrestrial environments; Water; Wetlands; California; United States; North America; America; Gas emission; Methyl chloride; Diurnal variation; Vegetation effect; Coastal zone; Biogenic factor; Salt marsh; Spatial distribution; Seasonal variation; Pollution source; Air pollution; Air ground interface; Quantitative analysis; Anthropogenic factor; Methyl bromide
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/35002043

Atmospheric methyl bromide (CH3Br) and methyl chloride (CH 3Cl), compounds that are involved in stratospheric ozone depletion, originate from both natural and anthropogenic sources. Current estimates of CH3Br and CH3Cl emissions from oceanic sources, terrestrial plants and fungi, biomass burning and anthropogenic inputs do not balance their losses owing to oxidation by hydroxyl radicals, oceanic degradation, and consumption in soils, suggesting that additional natural terrestrial sources may be important. Here we show that CH3Br and CH 3Cl are released to the atmosphere from all vegetation zones of two coastal salt marshes. We see very large fluxes of CH3Br and CH 3Cl per unit area: up to 42 and 570 µmol m-2 d -1, respectively. The fluxes show large diurnal, seasonal and spatial variabilities, but there is a strong correlation between the fluxes of CH 3Br and those of CH3Cl, with an average molar flux ratio of roughly 1:20. If our measurements are typical of salt marshes globally, they suggest that such ecosystems, even though they constitute less than 0.1% of the global surface area, may produce roughly 10% of the total fluxes of atmospheric CH3Br and CH3Cl.