Decomposition of Methyl Nitrite in Solutions and Soils

The role of hydrolysis as a process affecting the concentration of CH 3 ONO in the soil atmosphere was investigated by measuring the sorption of CH 3 ONO and the formation of NO ‐ 2 and NO ‐ 3 in two soils (−33‐kPa soil water potential) and three solutions in the dark at 20°C for 10 h. Soil pH and the pH of distilled H 2 O decreased on absorption of CH 3 ONO. In acidic solutions (distilled H 2 O and 0.1 M H 2 SO 4 ), > 90% of CH 3 ONO was recovered as NO ‐ 3 , whereas to an alkaline soil and 0.2 M NaOH, > 80% was recovered as NO ‐ 2 . Only 0 to 7% of CH 3 ONO remained in the atmosphere. In an acid soil only 50% of CH 3 ONO was recovered as [CH 3 ONO + NO ‐ 2 + NO ‐ 3 ]‐N. Recoveries of N in γ‐irradiated and nonirradiated soils did not differ significantly. The data indicate that CH 3 ONO was rapidly hydrolysed in solutions and in soils [CH 3 ONO + H 2 O ⇌ CH 3 OH + HNO 2 ], and that NO ‐ 3 formed via the self‐decomposition of HNO 2 . The low recovery of N in the acid soil may have been due to the participation of HNO 2 in chemodenitrification reactions. The rapid hydrolysis of CH 3 ONO is likely to inhibit the emission of CH 3 ONO formed in soils, and to cause the sorption of CH 3 ONO evolved from soils in closed systems.