HR: 0800h
AN: PP31A-0895    [Abstracts]
TI: Fluctuations of Sulfur and Strontium Isotope Ratios of Fish Specimens in Lake Biwa, Japan, During Recent 40 Years
AU: * Ito, T
EM: tito@mx.ibaraki.ac.jp
AF: Ibaraki University, Faculty of Education Bunkyo 2-1-1, Mito, 310-8512 Japan
AU: Tanabe, K
AF: Ibaraki University, Faculty of Education Bunkyo 2-1-1, Mito, 310-8512 Japan
AU: Ishii, R
AF: Ibaraki University, Faculty of Education Bunkyo 2-1-1, Mito, 310-8512 Japan
AU: Nishino, M
EM: nishino@Lbr.go.jp
AF: Lake Biwa Research Institute, Uchidehama, Otsu, 520-0806 Japan
AU: Tsujimura, S
AF: Lake Biwa Research Institute, Uchidehama, Otsu, 520-0806 Japan
AU: Nakajima, T
AF: Lake Biwa Research Institute, Uchidehama, Otsu, 520-0806 Japan
AU: Nakano, T
AF: Research Institute for Humanity and Nature, 335 Takashima-cho, Marutamachi-dori Kawaramachi nishi-iru, Kamigyo-ku, Kyoto, 602-0878 Japan
AU: Kiyokawa, S
EM: kiyokawa@geo.kyushu-u.ac.jp
AF: Kyushu University, Earth and Planetary Science 6-10-1 Hakozaki Higashiku, Fukuoka, 812-8581 Japan
AB: Sulfur and strontium isotopic fluctuations of lake water were reconstructed using fish specimens collected and preserved over 40 years. In this study, the first year and/or the second year fishes of Chaenogobius isaza from the northern part of Lake Biwa, Japan, were used. Each C. isaza was dissected, and the muscle tissue and the bone were subjected to sulfur and strontium isotope analyses, respectively. Delta 34S values of C. isaza showed monotonous decrease from +2.0 per mil of 1963 and -2.5 per mil of 2001. Considering sulfur isotopic fractionation between lake water sulfate to muscle tissue of C. isaza, it is suggested that delta 34S of lake water sulfate decreased from +5.0 per mil to +0.5 per mil during recent 40 years. A relative increase of sulfur contribution originated by human activities (~ - 4.0 per mil; Nakai et al., 1991) might be one of the main factors of the sulfur isotopic decrease, supposing from a rise in population and industrializing of the catchment area. Strontium isotopic ratios (87Sr/86Sr) of C. isaza slightly decreased from 0.7126 to 0.7124 during recent 40 years with distinct negative spikes (0.71195 to 0.71175) at 1980, 1983 and 1986. No specific change was shown in the trends of sulfur (this study) and nitrogen (Ogawa et al., 2001) isotope values at each of three years. Therefore, the drastic changes related to strontium circulation in Lake Biwa may have no influence on sulfur and nitrogen circulations.
DE: 4805 Biogeochemical cycles (1615)
DE: 4870 Stable isotopes
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting