Effects of Halomethyl-1, 3, 5-triazines on Nitrification

Abstract

To evaluate the effect of the halogenated methyl groups of 1, 3, 5-triazines on nitrification by nitrifying bacteria, twenty-six halomethyl-1, 3, 5-triazines were examined. Nitrification inhibition activity by the 1, 3, 5-triazines was determined through two experiments; i. e. The inhibition activities were measured for ammonia-oxidation to nitrate (NO₃^--N) in an upland soil and in the second one, for ammonia-oxidation to nitrite (NO₂^--N) by Nitrosomonas europaea ATCC 25978. The 1, 3, 5-triazines bearing trichloromethyl group (s) inhibited nitrification more strongly both in soil and in cell suspension of ATCC 25978 than other partially chlorinated methyl-1, 3, 5-triazines. The 1, 3, 5-triazines having tribromomethyl group (s) exhibited rather weaker nitrification inhibition in soil, although they indicated the strong inhibition in cell suspension. The halomethyl-1, 3, 5-triazines in this study inhibited ammonia-oxidation step, but did not inhibit hydroxylamine-oxidation step in the culture of ATCC 25978. This fact was found that the inhibitory target site of them may be on the ammonia-oxidation step from ammonium (NH₄⁺-N) to hydroxylamine (NH₂OH), as we found for trichloromethyl-1, 3, 5-triazines in our previous study.