Pedosphere 7(1): 9--14, 1997
ISSN 1002-0160/CN 32-1315/P
©1997 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| A unified model for the degradation kinetics of pesticides applied continually to soils |
| WANG Zong-Sheng, LIU Duo-Sen and ZHANG Shui-Ming |
| Institute of Soil Science, Academia Silica, P. O. Box 821, Nanjing 210008 (China) |
| ABSTRACT |
This paper deduces a kinetic model for microbial degradation of pesticides in soils:
x = x0 (M/M-m0+m0exp(μt))km/μ
where x is the concentration of pesticide at time t, x0 the initial concentration of the pesticide, m0 the initial number of pesticide-degrading microorganisms, M the carrying capacity for the microorganisms, Ea the specific growth rate of the microorganisms, and k the rate constant for the pesticide degradation. In periodic applications of pesticides, this model can be used to continuously describe every degradation curve. Whether a lag phase occurs or not, we can obtain the minimum residue of the pesticide (xe):
xe = xdexp(-kMτ)/1-exp(-kMτ)]
where τ is the regular time intervals between applications, and xd the dosage of the pesticide. |
| Key Words: microorganisms, pesticide degradation, unified model |
| Citation: Wang, Z. S., Liu, D. S. and Zhang, S. M. 1997. A unified model for the degradation kinetics of pesticides applied continually to soils. Pedosphere. 7(1): 9-14. |
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