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Degradation and adsorption of tebuconazole and tribenuron-methyl in wheat soil, alone and in combination
Wang, Feifei; Wang, Zhi; Zhang, Baohua & Zhang, Qingming
Abstract
In practice, pesticides are usually simultaneously applied
or one after another for crop protection. This often leads
to a coexistence of pesticide mixtures in soil. One of
the most important processes influencing the behavior
of a pesticide in the environment is its degradation and
adsorption in soil. Thus, the degradation and adsorption
behaviors of tebuconazole (TEB) and tribenuron-methyl
(TBM) alone and combined application in wheat soil
(pH 7.28) were studied. The concentrations of TEB and
TBM in soil were determined using a quick, easy, cheap,
efficient, rugged and safe method (QuEChERS) with ultrahigh-
performance liquid chromatography tandem mass
spectrometry (UHPLC-MS/MS). Results showed that TEB
has longer half-lives compared with TBM in the tested
soils when they were applied individually. The degradation
of TEB was markedly affected by concentration and soil
microorganisms. In the non-sterilized soil, half-lives of 0.8
and 80 mg kg-1 TEB were 16.4 and 69.3 d, respectively,
and half-lives of 0.8 and 80 mg kg-1 TEB were 20.4 and
73.5 d in the sterilized soil, respectively. The degradation
of TBM was not affected by TEB in both soils; however,
TBM could reduce the degradation of TEB. Compared to
TEB alone, the rates of degradation of 80 mg kg-1 TEB
in presence of 32 mg kg-1 TBM were reduced 15.9% and
18.2% in non-sterilized and sterilized soils, respectively.
Soil adsorption affinity of TEB was significantly higher
than TBM. When used combined, adsorption capacity of
TEB was not affected by TBM. However, the adsorption
of TBM was obviously inhibited in presence of TEB.
Keywords
Adsorption; combined pollution; degradation; tebuconazole; tribenuron-methyl.
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