Binding of nitrite-N on polyphenols during nitrification

Abstract

The conversion of substantial amounts of ammonia nitrogen into organic nitrogen as a direct result of nitrification at neutral pH-values, was monitored in soil suspensions amended with ammonium nitrogen. The influence of the chemolithotrophic nitrifying bacteria was verified by applying nitrapyrin as a selective inhibitor in control experiments. In addition, the role of phenolic compounds was examined by adding a naphthol. The factors influencing the nitrification process i.e. pH, NH+-N, NO~-N, NO~-N were measured during a 60 days incubation period. Nitrification started to be active after 5 and 10 days in the normal and the naphthol spiked soil suspensions respectively; it was inhibited in the nitrapyrin controls. Parallel with nitrification, formation of organic nitrogen was observed. The humic matter fractions were extracted and analyzed by I.R. spectroscopy which revealed the valence vibration ranges of nitro and nitroso groups fixed in different positions on aromatic compounds, both for normal and naphthol spiked samples. High resolution gas chromatography combined with mass spectroscopic analysis indicated the formation of nitrosonaphtholes. In addition a novel organic nitro compound was identified i.e. an azido nitro benzene. No nitrogen was fixed in the samples treated with nitrification inhibitor. A mechanism for the fixation of nitrite nitrogen during nitrification is proposed.

Effects of liming on carbon and nitrogen mineralization in coniferous forests

“…Chemical immobilization of NO2-, as suggested by Azhar E1 Sayed et al (1986), seemed to be of lesser quantitative importance for the reduction of the amount of inorganic N.…”

Fast nitrate immobilization in N saturated temperate forest soils

“…Microbial immobilization (Myrold and Tiedje, 1986;Paul and Clark, 1996) and abiotic ®xation (Nommik and Vahtras, 1982;Schimel and Firestone, 1989;Strickland et al, 1992;Vitousek and Matson, 1985) of ammonium (NH 4 + ) in soils have been well documented. While microbial immobilization of NO 3 À has been documented (Davidson et al, 1992;Stark and Hart, 1997), abiotic immobilization of the nitrite formed during nitri®cation (via nitrosation reactions) is the only known abiotic mechanism for NO 3 À immobilization (Azhar et al, 1986) and its signi®cance in the ®eld has not been demonstrated. Nonetheless, NO 3 À may comprise half or more of the N deposited on terrestrial ecosystems (Lovett, 1994) and may be produced by nitri®cation in N enriched stands.…”

Functional role of DNRA and nitrite reduction in a pristine south Chilean Nothofagus forest

“…In old-growth forests (''climax ecosystems'') the inhibition of autotrophic nitrification is caused by the absence of Nitrobacter, a bacterial group responsible for the NO 2 -oxidation to NO 3 - (Rice and Pancholy 1972). Furthermore, other processes such as nitrifierdenitrification (Wrage et al 2001), chemo-denitrification, a non-enzymatic chemical reaction of NO 2 -with organic N (Paul 2007;Sprent 1987), nitrosation, a mechanism of NO 2 -reaction with phenols to form organic N (Azhar et al 1986;Paul and Clark 1996), self-decomposition to NO 3 -under acidic conditions (Van Cleemput and Baert 1976) and the recently discovered anaerobic NH 4 ? oxidation (anammox) (Mulder et al 1995;Paul 2007) are also involved in the soil NO 2 -dynamics and in the production of gaseous N components.…”