Hydrochemical composition of glacial lakes on inshore Russian Antarctic stations
Introduction
The total area of Arctic and Antarctic polar regions amounts to about 10% of the Earth’s surface, 50% of which is occupied by landmass (Ryanzhin et al., 2010). Lakes are a sizable portion of polar regions’ ecosystems. There are a large number of lakes in Antarctica; in the current study region in the Larsemann oasis there are about 150 lakes, the majority of which are fresh-water lakes (Polar, 2008). About 60 lakes are situated on Fildes peninsular (Simonov, 1973). Analysis of the chemical composition of Antarctic lake waters is mainly confined to single measurements, from after the 1970s (Shmideberg and Bardin, 1985; Burgess et al., 1988; Kaup et al., 1988; Galchenko, 1994; Klokov et al., 1989; Burgess and Kaup, 1997; Andronikov and Foley, 2001; Lyons et al., 2002; De Carlo and Green, 2002; Quayle and Convey, 2006). The dominant type of water in the majority of Antarctic lakes is chloride water, of the sodium family (Azarova et al., 2008; Skorospekhova et al., 2016).
Polar lakes are particularly sensitive to human-induced impacts. Early data on the content of heavy metals in Antarctic lakes were presented in the work of Boswell and Wilson (1967). Then the investigations of heavy metals geochemistry were proceeded in studies (Gasparon and Burgess, 2000; Kaup and Burgess, 2003; Gasparon and Matschullat, 2006; Polar, 2008). Lake sediments reflect physical, chemical and biological information on the ecological changes which take place in the lakes, as well as on their watersheds. The study of the lakes’ sediments gives insights into the anthropogenic influence of long-range transmission of pollution to the Antarctic. Thus, enrichment of surface layers of bottom deposits with lead in two Antarctic lakes may be indicative of long-range transmission of foreign matters (Berry et al., 1985). Similarly, Mentasti et al. (2015) examined water from several Antarctic lakes, bottom deposits, weeds and adjacent soils to determine human-induced impacts on water composition. Factor analysis showed that soil samples around the lakes and samples of bottom deposits had identical chemical compositions, with a correlation of 0.988. High inter-annual variability of concentrations of metals was also observed (Mentasti et al., 2015). Contamination of the Southern oceans’ waters, Antarctic snow sheets, soils and biota was reviewed by Bargagli (2005), who demonstrated that the most persistent atmospheric pollutants originate from man-made sources of other continents, located mainly in the Southern hemisphere. These regions have experienced large increases in population and it is highly likely that in the near future their contribution to global emissions of greenhouse gases and persistent pollutants will increase significantly (Bargagli, 2005). In surface waters of Antarctic lakes concentrations of lead and other metals are low (Osamlj et al., 1979; Ornella et al., 2004). The origin of this mist was determined on the basis of the proportions of lead in deepwater ice cores. A significant contribution of anthropogenic lead from South American sources and low levels of heavy metals in ice cores and in the waters of the Southern oceans were detected (Environmental, 2001).
Ideal conditions for studying biochemical cycles of microelements are available in the Antarctic. An examination of the geochemistry of molybdenum and arsenic and their stratification at low temperatures in two Antarctic lakes on was recently conducted (Yang et al., 2015). Concentrations of both molybdenum and arsenic increased towards the bottom with the formation of iron-sulfide minerals.
This paper presents the chemical composition of water taken from 12 lakes of Western and Eastern Antarctic for the purpose of evaluating the current status of coastal glacial lakes: Progress, Reid, Scandrett, Stepped, Law, Discussion, Cameron, Bazovoe, Haswell, Kitezh, Slalomnoe (Svyatoe), Dlinnoe which are located nearby Russian Antarctic stations Progress, Druzhnaya-4, Mirny in the area of Larsemann Hills (Eastern Antarctica) and the Fildes peninsula (Western Antarctica). The first results detailing chemical composition of these lakes are given in previously published works (Gasparon and Burges, 1999; Burgess and Kaup, 1997; Burgess et al., 1988).
Section snippets
Methods
In Western Antarctica the study was carried out on the Fildes peninsula of King-George island (station Bellingshausen); in the eastern Antarctica on Larcemann’s hills, Princess Elizabeth Land (station Progress, Druzhnaya -4) and on the Mirny peninsula, Queen Mary Land (station Mirny). The lakes are located in proximity to polar camps. The natural regime of some lakes is affected by human activity. Some of the examined lakes are the source of fresh and service water for the polar stations. Water
Ionic composition
The chemical composition of surface waters is determined by a combination of natural and human -induced factors, which influence the behavior of various processes in the water column, bottom sediments and in bottom water at the interface of solid and liquid water. The main source of lake waters is glacial meltwater; nevertheless various studies have revealed both diversity of composition and sources of lake waters (Green et al., 1989; Loopman and Klokov, 1990; Andronikov and Foley, 2001). The
Discussion
To determine the contribution of various sources to the chemical composition of water of the lakes we examined coefficients of enrichment of water in relation to sea water according to:Ki = [(Ci/Na+)lake]/[(Ci/Na+)sw],where (Ci/Na+) is the concentration of i element with respect to Na+ in a lake (lake) and in sea water (sw) and K is the coefficient of enrichment (Tsunogai et al., 1972). The coefficients of enrichment of ions of lake water were essentially close to unity (Fig. 2). This may be
Conclusions
The main factors determining the chemical composition the lakes examined in this study are sea aerosols, glacier melt water runoff in summer, ground waters and growth of flora and fauna. Water of lakes can be classified either as “sweet water” or water with increased mineralization. Mineralization of lakes is unstable and changes from year to year. Water of Lakes Progress, Scandrett, Reid, Law, Discussion, Cameron, Bazovoe, Haswell, Kitezh, Slalomnoe was classified as chloride-sodium, of Lake
Acknowledgements
The reported study was supported by the Russian Foundation for Basic Research (RFBR) [research project No. 15-55-16001].
Authors express profound gratitude to senior research scientist, Cand. Sc. (Chemistry) of Limnologic Institute Chebikin E.P, who participated in samples collection of water from lakes in 55 RAE. We thank two anonymous referees for helpful and constructive comments.
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