Abstract: By using static replacement method, this paper studied the effects of different Pb concentrations (0, 0.2, 0.8, and 1.6 mg·L^-1) in water on the activities of alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and creatine kinase (CK) in the blood of juvenile Chinese sturgeon (Acipenser sinensis). To start with the zygote having developed for 96 hours, the juveniles were exposed to Pb for 16 weeks, and then transferred to Pb-free water for 6 weeks. After Pb exposure, the ALP activity in the blood presented a downward trend with increasing Pb concentration, and the decrease was significant when the Pb concentration was 1.6 mg·L^-1 (P<0.01). The activities of LDH and CK in the blood increased with increasing Pb concentration, and only LDH activity had a significant increase when the Pb concentration was 1.6 mg·L^-1 (P<0.05). The CK activity in the blood was more sensitive to Pb, which was 7 times higher when the Pb concentration was 0.8 mg·L^-1, and 19 times higher when the Pb concentration was 1.6 mg·L^-1, compared with the control (P<0.01). After 6-week recovery in Pb-free water, the ALP activity in the blood still presented a downward trend with increasing Pb concentration, but no significant differences were observed among all treatments (P＞0.05). The LDH activity in the blood also had no significant differences among the treatments (P>0.05). After transferring to Pb-free water, the ALP activity in the blood had somewhat recovery, whereas the LDH activity recovered significantly. It was considered that after exposure to 1.6 mg·L^-1 of Pb, the juvenile A. sinensis could have metabolic abnormality and tissue (liver or muscle) injury. The CK activity in the blood was more sensitive than the ALP and LDH activities, and thus, could be used as a useful index of Pb pollution for fish.

Key words: Urban forest, Landscape element, Scale, Interior habitat, Landscape pattern