Speciation of volatile mercury species present in digester and deposit gases

Volatile mercury compounds have been speciated in gases evolved from fermen tation of sewage sludge as well as municipal waste, The species were trappe d by sequential sampling, using a noble-metal trap in series with an activa ted-carbon trap. Thermally desorbed Hg-0 and (CH3)(2)Hg were separated by G C at 70 degrees C and detected by cold vapour atomic fluorescence spectrosc opy after thermal reduction. The amounts of mercury detected in the sewage gas correspond to concentrations in the range 50-110 ng m(-3) for both spec ies whereas the deposit gases were found to contain only elemental mercury. Monomethylmercury species could not be positively identified in any of the gas samples. Copyright (C) 1999 John Wiley & Sons, Ltd.