Rate of reaction between the nitrate radical and dimethyl mercury in the gas phase

Rate coefficients for the reaction of the nitrate radical with dimethyl mercury (DMHg) have been determined. The absolute rate was measured at temperatures from 258 to 358 K in the pressure range between 2.7 and 5.0 hPa using the fast-flow-discharge technique. The Arrhenius expression is 3.2 × 10−11 exp[−(1760 ± 400)/T] cm3 molecule−1 s−1, corresponding to a rate coefficient of 8.7 × 10−14 cm3 molecule−1 s−1 at 298 K and an activation energy of 14.6 ± 3.3 kJ mol−1. The atmospheric lifetime of DMHg with respect to NO3 radicals is 4 h at a radical concentration of 1 × 109 molecules cm−3. Elemental mercury was identified as a minor reaction product.