咪唑烟酸在浙江4种代表性土壤中的光解深度研究

运用模拟太阳光研究了咪唑烟酸在浙江4种代表性土壤中的光解深度，分析了土壤不同湿度对光解深度的影响，并初步探讨了光解深度与土壤各性质之间的相关性．结果表明：咪唑烟酸在4种风干土壤的光解深度分别在0．07～0．14mm之间，并以黄红壤的光解深度最浅，海涂土的光解深度最深；而在60％田间持水量的土壤中，4种土壤的光解深度比风干土壤平均提高2～3倍，并以黄红壤的光解深度最浅，小粉土的光解深度最深．湿度的加大，使得咪唑烟酸在土壤表面的吸附作用减弱，影响了其光化学行为，并且在土壤中其它化学物质的光诱导下，水分子可以产生羟基自由基，这些氧化剂可深入到土壤深部加速了咪唑烟酸的氧化分解，从而提高了其光解深度．不同土壤影响咪唑烟酸光解深度的关键因素为其pH值，土壤中OH^-可催化咪唑烟酸的光解反应，起到了一种光敏剂的作用．光解速度的加快，进一步可促进下层咪唑烟酸的向上迁移，导致其光解深度明显增加．

Study on photolytic depth of imazapyr in four representative soils of Zhejiang province

The photolytic depth of imazapyr was studied in four soils,which were representative in Zhejiang province,under simulated sunlight,and the effects of moisture and characteristics of the soils on it were also investigated.Results showed that the photolytic depth of imazapyr varied from 0.07 to 0.14 mm in four air-dried soils,among which the greatest depth and the slightest depth occurred in coast soil and yellow red loam soil,respectively.However,the photolytic depth in the presence of 60% of maximum water-holding capacity(WHC) increased 2~3 fold over that of the air-dried soil,and the greatest and slightest depth were monitored in powder soil and yellow red loam soil,respectively.Firstly,the increase of moisture resulted in the weak adsorption of(imazapyr) in soil, which influenced its photolytic behavior in soil surface.In addition,under the light-inducing of other soil chemicals,the water molecule can be converted to OH~-,which can oxidate imazapyr,thus,accelerating its degradation and enhancing its photolytic depth in soil.By comparison of the effect of each soil parameter on imazapyr photolytic depth,the most remarkable factor was pH value.