A laboratory study of freeze-thaw and the associated factors affecting nitrous oxide emissions during and after soil thawing

The objective of the study reported in this thesis was to investigate freeze-thaw and the associated factors' affecting nitrous oxide (N{dollar}sb2{dollar}O) emissions during and after soil thawing. The study was carried out in a temperature controlled environment. Gas samples were collected from a flow-through soil chamber and a Tunable Diode Laser Trace Gas Analyzer was used to detect the N{dollar}sb2{dollar}O fluxes from the chamber soil. Various experiments were conducted to study the effects of soil freezing and thawing, soil temperature, soil structure, and soil moisture content on N{dollar}sb2{dollar}O emissions; results are presented and discussed.; From the experiments, it was concluded that the significant N{dollar}sb2{dollar}O emissions occurring after soil thawing were mainly due to microbial activity. Freezing and thawing temperature, soil structure and moisture content strongly affect the N{dollar}sb2{dollar}O emissions after soil thawing. A co-existing soil nitrification and denitrification appeared to be the controlling mechanism of this N{dollar}sb2{dollar}O release.