A kinetic study of the gas-phase reaction between the hydroxyl radical andatomic mercury

The atom is the dominating species of mercury in the atmosphere. Its oxidat ion processes are of great interest since it is mainly oxidised mercury tha t undergoes deposition and thereby spreads into the ecosystems and becomes bioaccumulated. The kinetics of the gas-phase reaction between atomic mercu ry and hydroxyl radical has been determined at room temperature and atmosph eric pressure of air by relative rate technique. OH radicals were produced by photolysis employing methyl nitrite. By using cyclohexane as the referen ce compound, the rate coefficient obtained was k(Hg-o + OH) = (8.7 +/- 2.8) x 10(-14) cm(3) s(-1) leading to natural lifetimes of mercury at global me an conditions of 4-7 month due to this reaction. (C) 2001 Elsevier Science Ltd. All rights reserved.