Hidrológiai Közlöny 1989 (69. évfolyam)
6. szám - Hegedűs János: A Duna bekterio- és fitoplanktonjának karbamid és laktóz felhasználási sebessége összetett szintetikus tápoldatban
332 HIDROLÓGIAI KÖZLÖNY 1989. 69. ÉVFOLYAM, 6. SZAM ve rates of the two parallel processes are thus readily monitored. The studies were performed in 1973, on samples taken from the Danube at River Station 1659 km. and having temperatures of 22—24 °C and of the prevailing Danube water. For the samples of 22—24 °C temperature lactose decompositon was found to predominateat the first reading (24 hours), the nutrient solution becoming acidified. Exceptions to this were observed in the summer period with alga counts higher than 25 million litre, when the higher rate of carbamide decomposition predominated. The readings on the second day (48 h) indicated invariably higher lactose decomposition rates. The results obtained on the samples maintained at the prevailing temperature of Danube water were as follows: 1. At low temperatures between 0 and +10 °C (Nov. to March) no activity wasd detected by the method applied over the firts two days. 2. Activity became detectable above 10 °C. 3. Interesting phenomena were observed when the Danube water fx is between 10.1 and 14.5 °C. The samples maintained at 22—24 °C show pronounced acidification on the first and second days alike. On the other hand those studied at temperaratures between 10.1 and 14.5 °C show slight alkalinization (pH=7.1) following the first day, the process continuing thereafter (pH=7.5). This phenomen is observable in the spring and autum periods alike, but only in the aforementioned temperature interval. It appears in summed, too, whenever the temperature of Danube water sinks below 14.5 °C. 4. At water temperatures between 14.6 and 16.0 °C the two processes have approximately identical rates. 5. At temperatures from 16.1 up to 22.8 °C lactose decomposition predominated on both days. Exceptions to this are the periods with alga counts higher than 25 million/1, when carbamide decomposition was more pronounced after the first day. Keywords: bacterioplancton, phytoplancton, carbamide, lactose, temperature, activity, Danube. HEGEDŰS JÁNOS Szakmai munkásságának összefoglalóját a Hidrol. Közlöny 1989. 5. számában közöltük. Budapesti árvízi képek : III. A fazekas-tér Budin. (Fénvkep ut»n.)
