Herbicde application may affect dissolved oxygen DO, dissolved carbon dioxde and in ponded water, and of the water which is the water aerated with the atmoosphere.ln the presentstudy,DO concentration did not reach supersaturated state after herbicide application,and variation in DO decreased. The herbicide application reduced the diurnal variation in dissolved and increased the overall concentration,During the day, before the herbicide application, variaons in and were large,with highre than allowing absorption of from the air,whereas at night,the relationship between inverted.Application of the herbicide caused a reduction in exceeded throughout the reminder of the day. After the herbicide application, average air throughout the day.Morrover,the ponded water apsorbed oxygen from the air during the day because DO in the ponded water did not ponded water absorbed oxygen from the air during the day brcause DO in the ponded water did not reach saturated concentions. These facts indicated that the ponded water absorbed from the air and emitted to the air throughout the day indicated that the ponded water absorbed from the and emitted the air throughout the day after the herbicide application.thus,herbicide application affects not only ponded water,but also the surrouding atmosphere.Key words herbicide application,paddy fied,dissolved oxygen DO