The Holocene 13,4 (2003) pp. 517–526 Holocene lake succession and palaeo-optics of a Subarctic lake

Abstract: Two diatom-based transfer functions for the reconstruction of past levels of dissolved organic carbon (DOC) and water colour were applied to fossil diatom species assemblages from a coastal isolation basin on the eastern shore of Hudson Bay. Diatom stratigraphic changes and the diatom-infe...

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Bibliographic Details
Main Authors: Northern Québec Canada, Reinhard Pienitz, Warwick F. Vincent
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2002
Subjects:
Key words
Diatoms
succession
lake sediments
dissolved organic carbon
DOC
water colour
palaeo-optics
ultraviolet radiation
UVR
Holocene
Subarctic
Québec
Canada
Hudson
Hudson Bay
Tyrrell
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.525.3345
http://www.cen.ulaval.ca/warwickvincent/pdffiles/167.pdf
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Summary:Abstract: Two diatom-based transfer functions for the reconstruction of past levels of dissolved organic carbon (DOC) and water colour were applied to fossil diatom species assemblages from a coastal isolation basin on the eastern shore of Hudson Bay. Diatom stratigraphic changes and the diatom-inferred patterns of limnological change following the retreat of Holocene marine waters of the Tyrrell Sea revealed a highly variable Holocene lake trajectory associated with successional shifts in lake catchment vegetation and soil development. The main trends observed in the Holocene history of Lake Kachishayoot are: (1) a progressive loss of alkalinity over time; and (2) abrupt increases in DOC and water colour that coincide with the arrival of spruce (Picea mariana) in the catchment. Reconstructed DOC allowed the estimation of past depths of ultraviolet (UV) penetration in the water-column of Lake Kachishayoot. Past variations in biological UV exposure were inferred using optical models based on DOC concentrations and the response curves for DNA damage and UV photoinhibition of photosynthesis. The palaeoecological analyses revealed large changes in the underwater photobiological environment over the course of the Holocene period, from extremely high UV exposure after the initial forma-tion of the lake and its isolation from the sea, to an order-of-magnitude lower biological UV exposure under the present conditions of catchment vegetation.

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