下水処理水の放流を受ける河川感潮部におけるN₂Oの挙動

抄録

Transport of nitrous oxide and treated waste water was investigated in an estuary receiving treated waste water. Seasonal change of water quality were also observed to assure origins of N₂O and to estimate the influence of treated waste water on N₂O production in the survey area. Based on nitrous oxide concentration profiles in the survey area, discharged treated waste water were traced, which flowed upstream at the flood tide and downstream at the ebb tide with concentration maxima. It is assumed that nitrous oxide discharged from treated waste water is transported to the survey area with partial and vertical mixture. To determine the production of N₂O in survey area, flux at each sampling sites were calculated and 25% of the produced N₂O was originated from treated waste water in result. The remaing percentage of the production, and also assumed to be the discharge from the sediment layers.