抄録
The sampling time in a day and the day of the week were investigated to evaluate the effects of unchlorinated activated sludge effluent from the municipal sewage plant on the growth of Porphyra yezoensis by means of in vitro shaking culture. Effluents examined were sampled, before the chlorination occurred in the sewage plant, every two hours in one day and every day at 15:00 over one week. To clarify the difference in the effects on the Porphyra thalli, the thalli length and the absorbance spectra were measured, and dead cells were observed. Hourly sampled efliuents (Thursday-Friday) were classified roughly into three time zones from a standpoint of the effects on the growth ofPorphyra thalli, they were 11:00-17:00, 21:00-next day 5:00 and transition time zone. Effluent sampled daily at 15:00 were classified roughly.into three types from a standpoint of the growth of the Porphyra thalli: samples collected from Tuesday to Friday, on Saturday and from Sunday to Monday.
The above mentioned results suggested that normally, the sampling time zone and day of the week to evaluate the effects of activated, unchlorinated effluent may be (1) 13:00-17:00 on Sunday, on Monday and on one of the day's from Tuesday to Thyrsday and (2) 23:00-next day 1:00 on Sunday and on one of the day's from Tuesday to Friday.
