ACETYLENE AS A POSSIBLE SUBSTRATE IN THE DENITRIFICATION PROCESS

• Published in: Canadian journal of soil science 1982-01, Vol.62 (1), p.139-144
• Main Authors: YEOMANS, JANE C., BEAUCHAMP, E. G.
• Format: Article
• Language: English
• ISSN: 0008-4271; 1918-1841
• DOI: 10.4141/cjss82-015

The possible involvement of acetylene (C 2 H 2 ) as a carbon substrate in the denitrification process was studied in the laboratory with Brookston silty clay. Two experiments of 360 and 600 h durations, respectively, were conducted with saturated soil with or without C substrate (1% wt/wt ground alfalfa) and C 2 H 2 (1.0 kPa) in an He environment. Incomplete reduction of NO 3 − to N 2 O and N 2 occurred in the absence of both C substrate and C 2 H 2 . With C substrate but without C 2 H 2 , complete reduction of NO 3 − to N 2 was observed. In the absence of C substrate and in the presence of C 2 H 2 , N 2 O production was higher than in the absence of both C substrate and C 2 H 2 and complete reduction of NO 3 − to N 2 O and N 2 was observed. With both C substrate and C 2 H 2 added, there was complete conversion of NO 3 − to N 2 . A decrease in C 2 H 2 concentration was observed in the absence of C substrate. Production of C 2 H 4 or CO 2 did not account for this decrease in C 2 H 2 concentration. When N 2 O and C 2 H 2 were introduced together into preincubated flasks, N 2 O concentration showed an initial increase and then a decrease. A decrease in C 2 H 2 concentration was also observed. Again, this decrease was not accounted for by either C 2 H 4 or CO 2 production. Increases in the production of N 2 O and N 2 gases and decrease in C 2 H 2 concentration in the absence of C substrate suggested that C 2 H 2 enhanced denitrification. No conclusive data were obtained to suggest that C 2 H 2 acts as a carbon source during denitrification.