Kinetics of Losses of PCNB and DCNA in Three California Soils
1972
Wang, Zhenhua | Broadbent, F. E.
The losses of two fungicides, PCNB (pentachloronitrobenzene) and DCNA (2,6-dichloro-4-nitroaniline) in three California soils differing in their properties were measured in laboratory experiments. Under controlled temperature and moisture content, both fungicides were lost according to first-order kinetics. The calculated half-time (t½) was employed to indicate the stability or the persistence of the fungicides. The half-times of PCNB were found to be 4.7, 7.6, and 9.7 months for Columbia fine sandy loam, Sacramento clay, and Staten peaty muck, respectively, while those of DCNA were 30, 16.2, and 13.6 months, respectively. Thus higher soil organic matter was associated with slower PCNB loss but enhanced DCNA loss. It was also found that clay affected losses of the fungicides in a similar way. Evidence was obtained to show that PCNB was lost mainly through volatilization whereas DCNA was lost through microbial degradation and other processes.
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