Formation of Methyl Nitrite in Soil Treated with Nitrous Acid

The formation of methyl nitrite was detected when two clay soils were treated with nitrous acid (260 ± 20 mg N kg −1 soil) in the dark in a closed chamber. The presence of the gas was positively identified by mass spectrometry. There was a consistent trend with time in the concentrations of methyl nitrite in the atmospheres above the soils. A rapid buildup occurred following addition of nitrous acid, but this was soon followed by a gradual decline in concentration. The peak concentrations occurred approximately 15 min or 30 min after nitrous acid addition, and 5‐h concentrations were < 50% of peak concentrations. Methyl nitrite was formed under mildly to moderately acid conditions (pH 6.3 and 4.8) at −33 kPa soil water potential. The results indicate that methyl nitrite may form under conditions encountered in the field, and that soil can be a sink as well as a source of methyl nitrite.