In:
Journal of Geophysical Research: Atmospheres, American Geophysical Union (AGU), Vol. 106, No. D18 ( 2001-09-27), p. 20875-20882
Abstract:
Flux measurements in coastal sage scrub, chamise chaparral, and creosote bush scrub environments show that methyl bromide (CH 3 Br) and methyl chloride (CH 3 Cl), compounds that are involved in stratospheric ozone depletion, are both produced and consumed by southern California shrubland ecosystems. CH 3 Br and CH 3 Cl are produced in association with a variety of plants and are consumed by the soils, although there is a large variability in the fluxes, depending on predominant vegetation and environmental conditions. At sites with a net uptake of both compounds the fluxes of CH 3 Cl and CH 3 Br show a strong correlation, with a molar ratio of roughly 40:1, pointing to a similar mechanism of consumption. In contrast, the net production rates of these compounds show no apparent correlation with each other. The average observed net CH 3 Br uptake rates are an order of magnitude smaller than the previously reported average soil consumption rates assigned to shrublands. Extrapolations from our field measurements suggest that shrublands globally have a maximum net consumption of 〈 1 Gg yr −1 for CH 3 Br and 〈 20 Gg yr −1 for CH 3 Cl and may, in fact, be net sources for these compounds. Consequently, the measured net fluxes from shrubland ecosystems can account for part of the present imbalance in the CH 3 Br budget by adding a new source term and potentially reducing the soil sink term. These results also suggest that while shrubland soil consumption of CH 3 Cl may be small, soils in general may be a globally significant sink for CH 3 Cl.
Type of Medium:
Online Resource
ISSN:
0148-0227
DOI:
10.1029/2001JD000413
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
2001
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