Critical
key buffer capacity points in the soil pesticide tolerance
1Department
for Soil Science and Agricultural Chemistry, Szent István University, Páter
Károly Street, H-2103 Gödöllő, Hungary, imre.czinkota@gmail.com
2Department of Environmental
Engineering and Chemical Technology,
3Institute for Veterinary
Medicinal Products
Abstract: The bioavailability and mobility of a compound is
not only influenced by concentration and quantity, but also by the ability of
soil to recharge the compounds that plants have taken up from soil solution or
removed by the moving ground water. The effective diffusion and mass flow of
the compounds depends on the soils buffer capacity for that compound. The
buffer capacity in function of equilibrium concentration (EBC) can be calculated
as the first derivative of sorption isotherms. Using the measured and modelled
multi-step isotherms for this calculation we could get wave-shaping functions
where the maximums are bigger even ten times than the minimums in the 5-10%
interval of the whole soluble pesticide concentration. This result is
highlighting some problems what we have never been taken into account before:
Very small difference in the measured concentration can cover even ten times
more or less amount of pesticide in the soil and the capacity of the soil to
tolerate disturbance may also change even a magnitude in the aforementioned
interval.
Keywords: pesticide, adsorption,
buffering capacity