关键词: 车流量, 城市绿地系统, 叶面积指数, CO₂浓度, 稳定碳同位素

Abstract: The functions of extracellular polymeric substances (EPS) on microbial degradation of PAHs and the remediation of heavy metal polluted soil have been widely examined, but the mechanism of heavy metal stressing on the characteristics of EPS is not clear. In this study, the highly efficient PAHsdegrading fungus, Mucor mucedo, was cultured under the stresses of copper and lead ions, and their EPS characteristics were evaluated. Results showed that as the concentration of stressful metal ions increased from 0 to 80 mg·L^-1, M. mucedo EPS production (TOC), polysaccharide concentration (PS), protein concentration (PN), surface tension, emulsification index and Zeta potential (absolute value) gradually increased, with corresponding maximum values being 706.4 mg·L^-1, 1.035 mg·L^-1, 0.907 mg·L^-1, 57.63 mN·m^-1, 44.5%, and -26.21 mV, respectively. Except for emulsification index, M. mucedo EPS production, PS, PN, surface tension and Zeta potential (absolute value) decreased when the concentration of metal ions was over 80 mg·L^-1. Moreover, the physicochemical properties of EPS varied more obviously under Cu²⁺ stress than those under Pb²⁺ stress. The production, PS, PN, surface tension, emulsification index and Zeta potential (absolute value) of M. mucedo EPS could be enhanced under the copper and lead ion stress.

Key words: CO₂ concentration, traffic volume, stable carbon isotope, urban green space system, leaf area index