The Zn isotopic compositions of SPM (suspended particulate materials)and biological samples from the Hongfeng Lake and the Aha Lake as well as theirmain branches were analyzed with multiple collector inductively coupled plasma-mass spectrometry. The results show that the variations in Zn isotopic composition of SPM in the Aha Lake and in its main branches are -0.18‰～0.27‰ and -0.17‰～0.46‰ respectively, while the variations in the Hongfeng Lake and in its main branches are -0.29‰～0.26‰ and -0.04‰～0.48‰ respectively, indicating that the heavy zinc isotopes are enriched in the SPM in their branches. The zinc isotope compositions in biological material show a larger variation from -0.35‰ to 0.57‰, suggesting that different materials from the lacustrine ecosystem have their respective unique isotopic signatures. It is shown that the zinc isotope composition in the Aha Lake is mainly controlled by the water inputs from the catchment, and hence the zinc isotope composition can be used as a good tracer of source materials. It is also found that δ66Zn variation versus chlorophyll contents shows positive correlation (R=0.97) in the Hongfeng Lake in summer, which can be probably ascribed to the process of adsorption or absorption of zinc onto algae. In addition,the zinc isotope ratio of SPM in the Hongfeng and Aha Lakes in summer is lower than that in winter, implying that the atmospheric deposition might have served as another significant source of lighter zinc isotopes. Moreover, the variation of δ66Zn values in biological material is wider than that in SPM, indicating that inorganic processes controlling zinc isotope fractionation should be of subordinate importance compared with biological factor