Potentially Toxic Elements Infuence Diazinon Degradation Rate in Soil

The kinetics of diazinon degradation in
soils as aected by the presence of potentially toxic
elements was studied. Metal (Zn2+, Cd2+, V3+ and
Mn2+) treated soils as well as the control soils were
spiked with diazinon at two concentrations of 10,
and 50 mg kg-1. The residual diazinon concentrations
were measured by corona discharge-ion mobility
spectrometry at 0, 1, 10, 30, and 60 d. Degradation
time (DT50) was calculated using three kinetic
models. At 10 and 50 mg kg-1 of diazinon, no residual
concentration could be detected at the day 30 and 60,
respectively. In the Shervedan soil, the DT50 values
for 10 and 50 mg kg-1 spiked diazinon concentration
ranged from 0.51 to 2.3 d and 2.87 to 5.31 d, respectively.
The greatest and the lowest DT50 values were
consistently obtained in the control and V-treated
soil. In the Lavark and Chamaseman soil, the pattern
was similar to that of the Shervedan soil, except that
Zn was more stimulatory than V in the Lavark soil. In
general, metal-treated soils revealed lower diazinon
concentrations. For the rst time, it is reported that V
can enhance the rate of diazinon degradation in soils.