Japanese geochemical studies on the McMurdo Sound region in Antarctica during the 1983-84 austral summer

Abstract

During the 1983-84 austral summer, Japanese geochemical studies in the Dry Valleys and Ross Island of the McMurdo Sound region in Antarctica were carried out to observe the annual variation of the vertical distribution of physicochemical properties of waters for Lakes Bonney and Vanda, to clarify the changes of water quality of Lake Vanda for day and night, to characterize the physicochemical natures of lakes and ponds in the Labyrinth, South Fork and near Lake Vanda of the Wright Valley and around McMurdo Station of Ross Island, and to determine total carbonate materials (H_2CO_3+HCO^-_3+CO^_3=ΣCO_2) in lake and pond waters. The vertical distribution of physicochemical properties of Lakes Bonney and Vanda was similar to those of previous studies, indicating that the stratification of lake waters is still stable. Any remarkable changes in the vertical distribution of the water quality of Lake Vanda for day and night were not observed. The lakes and ponds in the Labyrinth (18 ponds), South Fork (3), near Lake Vanda (2), and sorroundings of McMurdo Station (2) studied were generally small and thus chlorinity varied considerably during these 10 years. The ponds with high pH values (>10) found in the Labyrinth and South Fork were considered to be mainly attributable to the photosynthetic activity of epibenthic organisms, which are widely distributed there. The ponds with extremely high dissolved oxygen (20-35ml/l) were also found in the Labyrinth as in the case of the surface waters of Lakes Bonney and Joyce in the Dry Valleys. The contents of the total carbonate materials for a depth of 15m to the bottom in the west lobe of Lake Bonney (55-69mM) were much higher than those of the lakes and ponds (>0.05-7.5mM) in the McMurdo Sound region, interesting in relation to their sources.