A series of laboratory-based incubations using a stable isotope tracer technique was applied to measure the net and gross fluxes of CH 3Cl and CH 3Br as well as the net fluxes of CHCl 3 from surface soils of the Sacramento-San Joaquin Delta of California. Annually averaged flux measurements show that these mineral/oxidized peat soils are a net source of CH 3Cl (140 ± 266 nmol m -2 d -1) and CHCl 3 (258 ± 288 nmol m -2 d -1), and a net sink of CH 3Br (-2.3 ± 4.5 nmol m -2 d -1). Gross CH 3Cl and CH 3Br fluxes are strongly influenced by both soil moisture and temperature: gross production rates of CH 3Cl and CH 3Br are linearly correlated with temperature, whereas gross consumption rates exhibit Gaussian relationships with maximum consumption at soil moisture levels between 20 and 30% volumetric water content (VWC) and a temperature range of 25 to 35 °C. Although soil moisture and soil temperature strongly affect consumption rates, the range of gross consumption rates overall is limited (-506 ± 176 nmol m -2 d -1 for CH 3Cl and -12 ± 4 nmol m -2 d -1 for CH 3Br) and is similar to rates reported in previous studies. CHCl 3 fluxes are not correlated with methyl halide fluxes, temperature, or soil moisture. The annual emission rates of CHCl 3 from the Sacramento-San Joaquin Delta are found to be a potentially significant local source of this compound.
|Original language||American English|
|Number of pages||9|
|Journal||Journal of Environmental Monitoring|
|State||Published - Jan 2012|
ASJC Scopus subject areas
- Public Health, Environmental and Occupational Health
- Management, Monitoring, Policy and Law