Hidrológiai Közlöny 1967 (47. évfolyam)

7. szám - A „Szervesanyag meghatározási problémák édesvizekben” című 1966. szeptember 25–28. között Tihanyben rendezett Szimpózium előadásai - Wetzel, Róbert G.: Oldott organikus vegyületek két indiánai tóban

302 Hidrológiai Közlöny 1967. 7. sz. Wetzel, R. G.: Oldott organikus vegyületek GLUCOSE ACETATE GALACTOSE FRUCTOSE 0 25 50 25 100 0 25 50 25 100 0 25 5

0 0 25JŰ'/0'

sm}l'' GLUCOSE ACETATE GALACTOSE FRUCTOSE ,1 5 10 15 20 300 400 K,*S„ 5 10 15 20 0 5 1

0 OSJO-IO^r'hr 400 0 200 4

00 0 20

0 400HQURS T, 111X64 3mi4 2 VIII64 0 5 10 15 20 / 0 5 10 15 : < 7 5 0 15 0 \> 0 50 100 150 I 100 200 300 0 L \ \ \ K

t+S

n 21 VIII64 21VIII64 26 VIII64 26 V!II64 Figure 3. Verticai distribution of the natural substrate concentrations (Kt + S

n), bacterial uptake velocities (V), and substrate regeneration times (T) for glucose, acetate, galactose, and fructose during stratification in Crooked Laké, Indiana. The progressive seasonal changes and consistent verticai differences in the substrate concentrations and rates of utilization of these four simple organic compounds suggests marked stratification in the bacterial populations. Estimates of the bacterial biomass during the course of this investigation are not available. Observed variations in the verticai and seasonal rates of substrate uptake velocity reflect not only variations in the quantitative bacterial populations but physiological stratification. Variations in species composition is surely the case in the hypolimnion of Little Crooked Laké and the lowermost portion of the hypolimnion of Crooked Laké where anaerobic conditions prevail during the terminál stages of stratification. Moreover, the variations in utilization of simple hexoses and of acetate among the same populations at a particular depth indicate specific uptake mechanisms. Differences in the transport constants may exist, althought they are probably small relative to the concentrations observed (cf. Wright and Hobbié, 1966). The concentrations of dissolved organic compounds observed were greater than anticipated. Further, they represent only a very small fraction of the totál quantity of dissolved organics in laké water. Preliminary investigations by the author with thin-layer chromatographic analyses have shown the presence of a large array of carbohydrates and aminő acids. Axenic cultures of aquatic macrophytes (e. g. Ghara, Najas) excrete moderate quantitites of simple organic compounds, especially aminő acids. Quantitites are increased considerably in contaminated cultures of macrophytes as would be anticipated. Planktonic algae excrete similarly large quantitites of simple organics (e. g. Fogg and Watt, 1965; Hellebust, 1965.). Furthermore, a large pool of more complex dissolved organic compounds are known from fresh waters (Shapiro, 1957, Povoledo, 1961, et segg.). All of these sources contribute to a large reservoir of organics that can influence inorganic biogechemical cycles. Figure 4. Verticai distribution of the natural substrate concentrations ( Kt + S

n), bacterial uptake velocities (V,) and substrate regeneration times (T) for glucose, acetate, galactose, and fructose during stratification in Little Crooked. Laké, Indiana Acknowledgments The author would like to expreSS his sineere appreciation to Dr. John E. Hobbié, now of North Carolina State University, for numerouS periods of fruitful discusSion and, with Dr. Richárd T. Wright, for details of their reSeareh prior to publieation. Harold L. Allén, W. K. Kellogg Biological Station, Michigan State University, alsó has entered into much stimulating discussion on these problems. Dr. Joseph Shapiro, University of Minnesota, kindly consented to preSent this paper at the Hungárián symposion "Problems of organic matter determination in freshwater". Much of the study reported here was undertaken while the author was affiliated with the Department of Zoology, Indiana University, Bloomington. Portions of the studies were supported by the National Science Foundation (Grant GB-1452) and Federal Aid Projects (F-7-R-2, -3, and -4). More recent work is being supported by the Atomic Energy Commission, Contract No. AT(11 —1)—1599, COO-1599—1. REFERENCES CITED Allén, H. A. (1967): Acetate utilization by heterotrophic bacteria in a pond. In: Hungárián SympoSium "Problems of organic matter determination in freshwater". (In preSB) Fogg, G. E. and W. D. Watt (1965): The kinetics of release of extracellular products of photosynthesis by phytoplankton. Mem. Ist. Ital. Idrobiol. 18 (Suppl.) : 165—174. Hellebust, J. A. (1965): Excretion of Somé organic compounds by marine phytoplankton. Limnol. Oceanogr. 10 : 192—206. Hobbié, J. É. and R. T. Wright (1965): Bioassay with bacterial uptake kinetics: glucose in freshwater. Limnol. Oceanogr. 10 : 471—474. Parsons, T. R. and J. D. H. Strickland (1962): On the production of particulate organic carbon by heterotrophic proceSses in Sea water. Deep-Sea Res. 18 : 211—222. Povoledo, D. (1961): Ulteriori Studi Sulle sostanze organiche disciolte nell'acqua del Lago Maggiore: frazionamento e Separazione delle proteine dai peptidi e dagli aminoacidi liberi. Mem. Ist. Ital. Idrobiol. 13 : 203—222. Schelske, G. L. (1962): Iron, organic matter, and other factors limiting primary productivity in a mari lake. Science. 136 : 45—46. Shapiro, J. (1957): Chemical and biological studies on the yellow organic acids of lake water. Limnol. Oceanogr. 2 : 161—179. Sorokin, J. I. (1959): Opredelenie velichin izotopicheskogo effekta pri fotosinteze v kulturakh Scenedes-