Isotope stratification of meromictic Lake Trekhtzvetnoe at the White Sea coast (Russia)

Annales de Limnologie: International journal of limnology

article

Yurij K. Vasil’chuk¹  Igor V. Tokarev²  Alla C. Vasil’chuk¹  Natalia L. Frolova¹  Nikolay S. Kasimov¹  Frank Winde³  Nadine A. Budantseva¹  Julia N. Chizhova⁴  Ludmila E. Efimova¹  Elena D. Krasnova⁵  Elena V. Terskaya¹ 

[1] Department of Geography, Lomonosov Moscow State University;Centre for Geo-Environmental Research and Modelling (GEOMODEL) at St. Petersburg University;School of Basic Sciences, North-West University Vaal Campus;Institute of Geology of Ore Deposits, Russian Academy of Science;N.A.Pertsov White Sea Biological Station, Lomonosov Moscow State University

关键词: White Sea;    separating lakes;    meromixis;    stratification;    stable isotopes;   

DOI  :  10.1051/limn/2018012

学科分类：地球科学(综合)

来源: EDP Sciences

【 摘 要 】

Postglacial isostatic uplift of the coastal zone resulted in the formation of isolated lakes along the shores of White Sea developed into permanently stratified (meromictic) lakes. On the basis of monitoring the vertical distribution of selected water quality parameters including temperature, salinity, concentration of major ions, microbial activity, dissolved oxygen and hydrogen sulfide, seasonal changes in the structure of the stratified water column are explored and governing factors identified. Lake Trekhtzvetnoe has a strong vertical stratification with seasonal mixing being confined to the upper part of the water column (mixolimnion). Сhemical water composition in the mixolimnion reflects the influence of precipitation with the underlying chemocline being defined by sharp gradients of salinity, dissolved oxygen and hydrogen sulphide levels. We found strong stable isotope stratification of water column in winter-early spring seasons of 2013, 2015 and 2016 and in the early autumn of 2015. The lowest isotope values were obtained near the surface in the mixolimnion. There was a gradual increase of isotope values towards the chemocline reaching the maximum in the bottom layer (monimolimnion). It was found that water in the mixolimnion was isotopically depleted in winter as a result of ice formation and isotopically enriched in the early autumn due to evaporation. Obvious desalination of mixolimnion and upper chemocline from 2012 to 2016 was possibly caused by the increase of precipitation and freshwater inflow in lake supply. Monimolimnion is a stable layer of high salinity, and it has enriched isotope composition that corresponds with meromictic structure of water column.

【 授权许可】

CC BY