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An estimate of the uptake of atmospheric methyl bromide by agricultural soils
Author(s) -
Varner Ruth K.,
Crill Patrick M.,
Talbot Robert W.,
Shorter Joanne H.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900071
Subject(s) - soil water , environmental chemistry , bromide , temperate climate , environmental science , chemistry , atmospheric sciences , soil science , biology , botany , geology , organic chemistry
Published estimates of removal of atmospheric methyl bromide (CH 3 Br) by agricultural soils are 2.7 Gg yr −1 (Gg = 10 9 g) [ Shorter et al., 1995] and 65.8 Gg yr −1 [ Serça et al., 1998]. The Serça et al. estimate, if correct, would suggest that the current value for total removal of atmospheric CH 3 Br by all sinks of 206 Gg yr −1 (based on Shorter et al., 1995) would be 30% too low. We have calculated a new rate of global agricultural soil uptake of atmospheric CH 3 Br from a larger sampling of cultivated soils collected from 40 sites located in the United States, Costa Rica, and Germany. First order reaction rates were measured during static laboratory incubations. These data were combined with uptake measurements we reported earlier based on field and laboratory experiments [ Shorter et al. 1995]. Tropical (10.2°–10.4°N) and northern (45°–61°N) soils averaged lower reaction rate constants than temperate soils probably due to differing physical and chemical characteristics as well as microbial populations. Our revised global estimate for the uptake of ambient CH 3 Br by cultivated soils is 7.47±0.63 Gg yr −1 , almost three times the value that we reported in 1995.