CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Fortin, M.-C.; and Gajewski, K.;
Date : 2007.
Title : Biogenic silica profiles spanning the Holocene for two Canadian Arctic lakes from Victoria Island.
Publication : CANQUA Ottawa 2007. Canadian Quaternary Association Conference, June 4-8, 2007. Carleton University, Ottawa, Ontario, Canada.
Issue :
Page(s) :
Abstract
An important goal of paleolimnological studies is to quantify past changes in the trophic status of Arctic lakes. Identifying these fluctuations in nutrient availability through time can help us better understand the effects of climate change on the productivity of the northern lakes. Biogenic silica extracted from the sediment matrix can be used as an indication of nutrient content as well as diatom concentration of lakes (Conley and Schleske, 1993; 2002). A high-resolution biogenic silica analysis was performed on sediment cores taken from two lakes on Victoria Island in the Canadian Arctic. Both lakes, of comparable depth and surface area, are located in polar desert vegetation, and have similar bedrock with moderate to high carbonate content. The cores span 8,500 and 12,000 years. The biogenic silica extraction from these cores was completed through the use of a wet-alkaline digestion technique (Conley, 1998). The sediment core WB02 from the Wynniatt Bay area of Western Victoria Island, has very low biogenic silica concentrations, with values less than 2.5 weight % BSi. These results, coupled with the absence of diatoms at most levels in this core, may strongly indicate chemical or mechanical silica dissolution in this lake throughout the Holocene. The second core, KRO2, taken from western Victoria’s Kuujjua River area, has much higher biogenic silica concentrations, ranging from 0 to 39 weight % BSi throughout the core. In both lakes, periods of marked increases of biogenic silica occur at around 6,600 and 3,500 years BP, and during the last 100 years BP. In site KR02, which is the longer of the two cores, there is also a strong peak in biogenic silica concentrations, at about 10,000 year BP. In both cores, one of the most rapid increases in biogenic silica concentrations occurs during the last 100 years. However, it is still unclear if this is a response to changes in the lake’s environment, or if it is simply because this more recent sediment has not yet undergone diagenesis.
Bibliography of Canadian Geomorphology