EMISSIONS OF MERCURY-VAPOR FROM TREE BARK

Measurements of the rate of elemental Hg vapor (Hg degrees) emissions from the bark of red maple (Acer rubrum L.), yellow-poplar (Liriodendr on tulipifera L.), chestnut oak (Quercus prinus L.) and white oak (Que rcus alba L.) were conducted in a controlled laboratory chamber with a mean air Hg degrees concentration of 1.6 ng m(-3). Measured Hg degree s emissions for the four bark species studied ranged from a maximum of 10.8 ng m(-2) h(-1) for white oak to a minimum of 1.2 ng m(-2) h(-1) for red maple. Chestnut oak, yellow-poplar, and red maple bark all had similar Hg degrees emission rates with a mean of 1.9 ng m(-2) h(-1), but the mean emission rates from white oak were up to five times great er. This discrepancy was correlated with higher rates of evaporation f rom the white oak bark samples. When compared to published values of H g degrees emissions from foliage and soils, it was concluded that bark surfaces would contribute less than 10% of all Hg degrees emissions f rom a forest landscape. Copyright (C) 1996 Elsevier Science Ltd.