Study on degradation law and residue level of pesticides in crop and environment are the most important basis for the evaluation of pesticide effects on environment and the building of regulations for the use of pesticides. Photodecomposition of pesticides is one of the most important degradation pathways occurring in natural environment and that has a direct impact on the efficiency and the degradation dynamics of pesticides. lodosulfuron-methyl-sodium is one of prospective high efficiency herbicides, the ...