Effect of Cu on the carbon transfer from medium to Daphnia magna has been studied. The concentration of Cu in the medium containing mixed algae was 0.1 ppm, 0.3 ppm and 0.5 ppm. The13C added in the medium was 20 mg/50mL as NaH13CO3. The temperature in the room used for incubation was controlled at 24°C and the light intensity at the medium (in 50 mL beaker) was about 3000 lux (14 hours: light, 10 hours : dark) . After 24 hour incubation, The Daphnia magna and the phytoplankton were dried and13C abundance of each sample were measured by a13CO2analyzer. The13C abundance in Daphnia magna were 2.9 atom% excess in control, 1.1 atom% excess in 0.1 ppm, 0.6 atom% excess in 0.3 ppm and 0.6 atom% excess in 0.5 ppm, respectively. And in phytoplankton, they were 6.7 atom% excess in control, 6.5 atom% excess in 0.1 ppm, 6.1 atom% excess in 0.3 ppm and 4.0 atom% excess in 0.5 ppm. The13C abundance in phytoplankton was not so decreased as in Daphnia magna. The lower13C abundance observed in Daphnia magna were mainly caused by the less intake of phytoplankton derived by the Cu in the medium.
The stable hydrogen isotope ratio (δD) in precipitation in Hachinohe is analyzed for the period from January 2000 to December 2003. The non-weighted mean δD for this period was -53.8‰, although the data exhibited wide scatter (5‰ to -200%‰) . The scatter is most pronounced in winter, attributable to the combination of precipitation originating from the Sea of Japan and the Pacific Ocean in this season. Lower δD values were observed in the Bai-u season and δD values of higher than -10‰ were recorded in spring and autumn. A rapid decrease in δD values following local dissipation of a typhoon was also recognized.