Geochemical characteristics of Antarctic lakes and ponds

Abstract: General characteristics of lakes and ponds, distributions, changes and sources of major ionic components (Na, K, Mg, Ca, Cl and SO4), nutrients and organic components in lake and pond waters and/or sediments of the McMurdo and Syowa Oases, Antarctica have been discussed from a geochemical viewpoint. Chloride ion contents of lake and pond waters range from 0.17 to 251 100 mg/kg. Total salt contents show bimodal distributions presumably reflecting the presence and absence of outflows, respectively. Generally, the relative abundances of Na, K, Ca, Mg and SOi decrease with increasing Cl contents, indicating that these ionic components deposit during concentration of dissolved salts in lakes and ponds through fractional freezing and/or evaporation of waters. Although contents of nitrate in the coastal lakes and ponds of the Syowa and Vestfold Oases are generally low, those in the oxic zones of the inland lakes and ponds of the McMurdo Oasis are often high. Nitrite concentrations in freshwater and saline lakes and ponds are generally low. Ammonium, phosphate and/or silicate released by the degradation of settled plankton are generally highly con