TABLE 6.

Half-lives of dibromomethane and methyl bromide due to bacterial oxidation, chemical consumption, and volatilization

Water	Half-lives (days) of:
	Dibromomethane			Methyl bromide
	Bacteriala	Chemicalb	Voltili-zationc	Bacteriala	Chemicald	Voltili-zationc
Freshwater	2			5	∼30
Estuarine	2			36	8–15
Seawater	2			82	∼5
Hypersaline-alkaline	1			298	∼3
All waters		4 × 104	∼1–16			∼1–16

^aValues were determined by using equation 2 and the k_app values in Table 4. 

^bData from reference 25. 

^cValues were determined by using the following expression: ln 2/KL, where K is the transfer velocity (1 to 4.2 m day⁻¹) (seasonal wind speeds, 0 to 20 m/s) and L is the mixed-layer depth (4 to 6 m for Searsville Lake, 2 to 40 m for San Francisco Bay, 11 to 23 m for Mono Lake, and 2 to 100 m for coastal seawater) (3, 14, 23, 28) (see also the following website: http://sfbay.wr.usgs.gov/access/wqdata). 

^dData from references 16 and 19. The temperature used was 23°C. Salinities are given in Table 1.