OH radical reactions are the major removal pathway for PCBs from the atmosphere
- Indiana Univ., Bloomington, IN (United States)
Polychlorinated biphenyls (PCBs) are transported through the environment primarily in the atmosphere and may undergo chemical reactions with the OH radical while in the vapor phase. Rate constants for the gas-phase reaction of 14 PCB congeners with the OH radical over the temperature range of 323-363 K were measured. The calculated temperature dependences of the reactions were used to estimate OH-PCB reaction rate constants at 298 K. These constants agree well with literature rate constants for PCBs containing 0-2 Cl and with rate constants estimated from a structure-activity method. Calculated atmospheric lifetimes of PCBs due to OH-initiated reactions varied from 2-34 days for PCBs with 0-5 Cl. A simple model for the vertical concentration gradient of PCBs in the troposphere was developed and used to calculate the total global loss rate (8,300 tonnes/yr) of PCBs from the atmosphere due to removal by OH. This pathway is very large in comparison to other known permanent PCB loss processes from the environment, such as deep ocean sediment burial (240 tonnes/yr).
- OSTI ID:
- 369993
- Report Number(s):
- CONF-960376--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Increasing PCB Radiolysis Rates in Transformer Oil
Aqueous-phase oxidation of polychlorinated biphenyls by hydroxyl radicals