Degradation of Pyridine Derivatives in Soil1
- Gerald K. Sims and
- Lee E. Sommers2
The fate of pyridine and 25 substituted pyridines in soil (Aeric Ochraqualfs) was examined by measuring the quantity remaining and the inorganic N released as a result of degradation of the pyridine ring for a period of 64 d. Each compound was added to soil at 2 mmol kg−1. Compounds studied included pyridine substituted with one or two hydroxyl, carboxyl, chlorine, amine, or methyl groups. During the 64-d incubation period, extractability of pyridine derivatives with 2 M KCl + 0.01 M HC1 decreased from an average of 88 ± 8.8% to essentially 0 for all compounds except aminopyridines. From 36 to 94% of added aminopyridines was recovered after 64 d of incubation. Degradation of the majority of pyridine derivatives was confirmed by accumulation of N in amounts equivalent to 61 to 80% of the decrease in extractable pyridines at 64 d of incubation. Degradation of unsubstituted pyridine occurred within 8 d, whereas most hydroxypyridines were degraded within 32 to 64 d. Pyridinecarboxylic acids appear to be the most labile group of pyridine derivatives and were dissipated from soil in 4 to 16 d. Most chloropyridines persisted in soil and became weakly associated with some insoluble soil component. However, 4-chloropyridine degraded in 16 d. Aminopyridines resisted degradation in soil while methylpyridines were degraded in 8 to 32 d. Degradability of the compounds generally followed the order pyridinecarboxylic acids > pyridine = mono-hydroxypyridines > methylpyridines > aminopyridines and chloropyridines. This trend was consistent with previous results on biodegradability of the compounds in soil suspension cultures.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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