Izvorni znanstveni članak

Trophic Characteristics of the Sapanca Lake (Turkey)

Enis Morkoç ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Süleyman Tugfrul ; Institute of Marine Sciences, Middle East Technical University, P.O.B. 28, TR-33731 Erdemli, Icel, Turkey
Murat Öztürk ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Hüseyin Tufekçi ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Leyla Egesel ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Vildan Tüfekçi ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Oya S. Okay ; Environmental Engineering Department, TUBITAK-Marmara Research Center, TR-41440 Gebze, Kocaeli, Turkey
Tarzan Legović ; Center for Marine and Environmental Research, Ruđer Bošković Institute, P.O.B. 1016, HR-10001 Zagreb, Croatia

Sažetak

Systematic measurements of optical properties, concentrations of major and minor chemicals and primary production throughout 1989-1992 enabled us to identify the oligotrophic state of Sapanca lake, Marmara region, Turkey. Lake waters which have low concentrations of major anions and cations (total = 49 μM) overturn every February-March, ventilating the bottom waters and enriching the surface waters with nutrients. Surface waters cool down to 6.5 °C by late winter and then warm steadily to 26 °C by late summer, while temperatures in deep waters range between 6.5 and 10.0 °C throughout the year. When the seasonal thermocline develops, the dissolved oxygen profiles exhibit a subsurface maximum in the thermocline, while in the hypolimnion water, the content varies seasonally from 11.5-12.0 ppm (350-375 μM) in March to 0.5-1.7 ppm (16-56 μM) in late autumn. Surface nitrate concentrations vary markedly with season, from < 0.15 μM in summer to 5.7 μM in early March, whilst the bottom water concentrations range from 13.5-14.0 μM in late autumn to 5.7 μM after the winter overturn. Phosphate concentrations are always less than 0.1 μM throughout the entire water column. Subsurface chlorophyll-a maximum descends in late summer to 20-25 m depths, where the light intensity is less than 1% of the surface value. Below 10-15 m depths, corresponding to the upper thermocline, primary productivity is very low. The range was from 35 to 93 mg C/ m2 day-1 during 1989-1991, consistent with the values in other oligotrophic lakes.

Ključne riječi

Hrčak ID:

132349

URI

https://hrcak.srce.hr/132349

Datum izdavanja:

4.5.1998.

Posjeta: 684 *