Binding of nitrite-N on polyphenols during nitrification |
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Authors: | Sayed El Azhar R Verhe M Proot P Sandra W Verstraete |
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Institution: | (1) Faculty of Agriculture, University of Gent, L 653 Coupure, Belgium;(2) Faculty of Sciences, University of Gent, Krijgslaan 281 (S4), B-9000 Gent, Belgium |
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Abstract: | Summary 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 α naphthol. The factors influencing the nitrification processi.e. pH, NH
4
+
−N, NO
2
−
−N, NO
3
−
−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 identifiedi.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. |
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Keywords: | Azido nitro benzene Nitrapyrin Nitrification Nitro and nitroso aromatic compounds Organic nitrogen Phenolic compounds |
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