The Larsemann Hills is an ice-free area of over 150 lakes that are not ice covered in summer. Despite being located at 69°30'S the area is not characterized to any extent by expected glacial indicators such as till, moraine or striations. Although the lakes show signs of evaporative lowering of water levels evolution to a saline state has not advanced to any great degree. While some evidence has been advanced to suggest only recent deglaciation (less than 10000yrBP) and large accumulations of ice (200–500m) it is now suggested that the area has not been glaciated during the Wisconsin to the extent previously claimed. The paper reports moss deposits aged 24950 yrBP that are significantly older than those previously reported for the area.

Abstract:This study aimed to use nutrients in lake inflows as proxies for assessing human impact and separating this from natural transformations of material in the soil active layer. Nutrients, conductivity and δ 18 O were monitored in surface and subsurface (using ceramic tipped piezometers) lake inflows during summer in near natural and human impacted catchments. The nutrient levels were highly variable but generally higher during the last weeks of the flow, in both subsurface waters and in human impacted catchments. Up to 2000 µgN l -1 subsurface dissolved inorganic nitrogen (DIN) was measured in human impacted catchments but only 315 µg N l -1 in natural catchments. Subsurface levels of dissolved reactive phosphorus (DRP) were up to 310 µgP l -1 in natural catchments and up to 108 µgP l -1 in human impacted catchments. The maximum levels of both DIN and DRP in surface inflows were much higher in human impacted than in natural catchments. Conductivity and δ 18 O data showed general enrichment of snowbank meltwater presumably through evaporation from the active layer. This combined with fluctuating nutrient levels in catchment waters indicated that soil brines and decaying organic matter of natural and human origin were possible sources for nutrients and other salts. Marked salinization and substantially increased DIN levels near the research stations indicated that lake waters were receiving nutrients generated by humans.

No abstract

No abstract