Rapeseed (Brassica napus) was quantified as one of the important terrestrial natural emitters of methyl bromide (CH₃Br) to the atmosphere. In this study, we planted rapeseed (B. napus "Empire") in the field (Oxford Tract, UC Berkeley) and measured weekly methyl halide fluxes (CH₃Cl, CH₃Br and CH₃I) using static-chamber measurements. The meteorological and physiological data, including air tempearture, plant height, leaf area, flowering number, biomass were also recorded over the life cycle of rapeseed.

Methyl halide fluxes were measured by static-chamber methods and the concentrations were analyzed by gas chromatography coupled with a mass spectrometry (GC/MS; Agilent 6890N/5973, Agilent Technologies, Santa Clara, CA).  Air temperature was recorded for every 10 minutes via sensors (HOBO U23 Pro v2 Data Logger, Onset Computer Corporation, Bourne, MA). For soil chloride and bromide measurements : a known amount (~10g) of soil powder was then placed into a centrifuge tube (BD Falcon, Becton, Dickinson and Company, Franklin Lakes, NJ) with 35 mL of deionized water and then shaken thoroughly for 20 min (Vortex Genie 2 Mixer, Fisher Scientific, Hampton, NH) to mix soil and water suspension to extract ions into the liquid phase. Afterwards, the mixed slurry was centrifuged for approximately 40 minutes at high speed setting to ensure that pellet and supernatant are well separated and packed. The aqueous extract was filtered with a #5 Whatman filter paper and a Buchner funnel, then being analyzed by chloride/bromide ion selective electrodes (Thermo Scientific, Waltham, MA).