Biogenic, biomass and biofuel sources of trace gases in southern Africa.

Biogenic processes in southern African savannas are estimated to produce 1.0 Tg NO yr -1 , 44.2-87.8 Tg C yrlsupg-1l/supg as non-methane hydrocarbons (NMHCs) and to consume 0.23 Tg CHlsubg4l/subg yr -1 . Floodplains and wetlands in southern Africa are estimated to generate between 0.2 and 10 Tg CHlsubg4l/subg yrlsupg-1l/supg (excluding the effects of aquatic vegetation on emissions). Biogenic emissions from the subcontinent's savannas constituted twice the amount of NO, and significantly exceeded the amount of NMHCs produced from biomass burning (0.55 Tg yr -1 for NO and 0.49 Tg yrlsupg-1l/supg as NMHCs) as well as that of industrial emissions (1.75 Tg NO yrlsupg-1l/supg and 0.61 Tg yrlsupg-1l/supg as NMHCs). Methane emissions from floodplains and wetlands could be more important than the combined effect of savanna burning (0.38 Tg yr -1 ), biofuel burning (0.24 Tg yr -1 ) and anthropogenic (2.59 Tg yr -1 ) emissions in the region. Biofuel combustion produces similar amounts of CO and NMHCs, half the amount of COlsubg2l/subg and CH 4 , and a quarter of the NO x that savanna burning does. Industrial emissions are shown to be important contributors to regional CO (5.6 Tg yr -1 ) and COlsubg2l/subg (360.0 Tg yr -1 ) emissions. These results indicate that biogenic, pyrogenic and anthropogenic sources all need to be considered in regional and national emission budgets, and as bases for the recommendation of policy and mitigation strategies within the region.