Dissolved organic carbon and fluorescence in Lake Hovsgol: factors reducing humic content of the lake water |
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Authors: | K Hayakawa T Sekino T Yoshioka M Maruo M Kumagai |
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Institution: | (1) Lake Biwa Research Institute, 1-10 Uchidehama, Otsu, Shiga 520-0806, Japan Tel. +81-77-526-4800; Fax +81-77-526-4803 e-mail: hayakawa@lbri.go.jp, JP;(2) Research Institute for Humanity and Nature, Kyoto, Japan, JP;(3) University of Shiga Prefecture, Hikone, Japan, JP |
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Abstract: | Lake Hovsgol is a large tectonic lake located in northern Mongolia, which has extremely transparent lake water. In our survey,
the dissolved organic carbon of the lake water was 80–100 μM-C, and the fluorescence intensity in an excitation and emission
matrix was very low. The brown color and high content of humic substances in river water flowing from a watershed consisting
of grassland and forests rapidly declined in the coastal area of the lake. The decrease in humic content may be due not only
to dilution by the lake water but also to flocculation and photobleaching. Among tectonic lakes in Asia, Lake Hovsgol would
appear to have unique biological and hydrological features that reduce humic content and help to maintain water transparency.
Received: June 25, 2002 / Accepted: January 10, 2003
Acknowledgments The authors acknowledge helpful discussion with Dr. J. Urabe. We thank Dr. T. Galbaatar, Mongolian Academy of Science, Mongolia,
for his arrangements on the expeditions in 1999. We are also indebted to Mr. D. Hadbaatar, B. Ganbat, and the cruise staff
of the R/V Suchbaatar for their assistance in the course of the study. This study was supported by Grant-in-Aid No. 09041159 and 13575034 for Scientific
Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Correspondence to:K. Hayakawa |
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Keywords: | Water color Dissolved organic carbon Fluorescence Excitation and emission matrix Humic substances |
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