Premium
Inhibition of Methane Oxidation in a Slurry Surface Crust by Inorganic Nitrogen: An Incubation Study
Author(s) -
Duan YunFeng,
Elsgaard Lars,
Petersen Søren O.
Publication year - 2013
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2012.0230
Subject(s) - slurry , anaerobic oxidation of methane , methane , oxidizing agent , environmental chemistry , chemistry , nitrogen , nitrate , ammonium , nitrite , incubation , inorganic chemistry , environmental engineering , biochemistry , environmental science , organic chemistry
Livestock slurry is an important source of methane (CH 4 ). However, depending on the dry matter content of the slurry, a floating crust may form where methane‐oxidizing bacteria (MOB) and CH 4 oxidation activity have been found, suggesting that surface crusts may reduce CH 4 emissions from slurry. However, it is not known how MOB in this environment interact with inorganic nitrogen (N). We studied inhibitory effects of ammonium (NH 4 + ), nitrate (NO 3 − ), and nitrite (NO 2 − ) on potential CH 4 oxidation in a cattle slurry surface crust. At headspace concentrations of 100 and 10,000 ppmv, CH 4 oxidation was assayed at salt concentrations up to 500 mM. First‐order rate constants were used to evaluate the strength of inhibition. Nitrite was the most potent inhibitor, reducing methanotrophic activity by up to 70% at only 1 mM NO 2 − . Methane‐oxidizing bacteria were least sensitive to NO 3 − , tolerating up to 30 mM NO 3 − at 100 ppmv CH 4 and 50 mM NO 3 − at 10,000 ppmv CH 4 without any decline in activity. The inhibition by NH 4 + increased progressively, and no range of tolerance was observed. Methane concentrations of 10,000 ppmv resulted in 50‐ to 100‐fold higher specific CH 4 uptake rates than 100 ppmv CH 4 but did not change the inhibition patterns of N salts. In slurry surface crusts, MOB maintained activity at higher concentrations of NH 4 + and NO 3 − than reported for MOB in soils and sediments, possibly showing adaptation to high N concentrations in the slurry environment. Yet it appears that the effectiveness of surface crusts as CH 4 sinks will depend on inorganic N concentrations.