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土壤粒径对农药在土壤中分布和光解的影响
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摘要:
以500W氙灯为光源研究了氯氰菊酯等农药在土壤不同粒径范围的光解速率以及农药加入土壤经充分平衡后在不同粒径范围的分布。结果表明,土壤粒径对农药在土壤中的分布和光解速率有显著影响。粘质壤土中,几种农药在0.1~0.25mm和0.25~0.5mm粒径范围含量最高,为混合土样的1.2~1.3倍;1.0~2.0mm粒径范围含量最低,为混合土样的0.78~0.9倍;砂质壤土中几种农药含量则随粒径增大而提高。氯氰菊酯等3种农药在粘质壤土和砂质壤土不同粒径范围的光解速率均以0.5~1.0mm范围最快,半衰期分别为34.07~42.78h(砂质壤土)和44.93~55.0h(粘质壤土);0.1~0.25mm粒径范围光解最慢,半衰期分别为56.50~77.70h(砂质壤土)和65.04~88.03h(粘质壤土)。
关键词:  土壤粒径 农药 光解
DOI:
基金项目:
Effects of Soi1 Particle Size on Distribution and Photodegradation of Selected Pesticides in Soil
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Abstract:
This paper reported the distribution and photolytic rates of cypermethrin, deltamethrin, fen-valerate and trifluralin in soil of different particle sizes. The results showed that soil particle sizehad significant effects on equilibrium amounts and photodegradation half-lives of the pesticides insoil. In two clay loam soils, much higher pesticide levels in particles of 0.25 and 0.5mm than thatin particle of 2. 0mm were detected, the levels in particles of 0. 1 and 1.0mm were approximatelyequal to the level in mixed soil samples, but in sandy loam, the pesticide levels increased with soilparticle sizes. Based on the photolytic rates of cypermethrin, deltamethrim, and fenvalerate in dif-ferent soil particles, the fastest photodegradation was observed in the particle size of 1.0mm andthe slowest photodegradation in the particle size of 0. 25mm, with the difference ratio of 1.64-1. 82 fold in sandy loam, and 1. 45-1.60 fold in clay loam.
Key words:  Soil particle size,Pesticides,Distribution,Photodegradation

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