Abstract: Surface albedo is a key factor of surface energy and hydrological cycles. Based on continuous monitoring of meteorological factors in an urban greenland in the Beijing Olympic Forest Park from 2013 to 2015, we explored the dynamics of surface albedo and its controlling factors. The diurnal variation in surface albedo gradually decreased from 08:30 am to 12:00 pm, and then remained relatively constant to 17:00 pm. Surface albedo in the morning was 0.03 higher than that in the afternoon. The asymmetry of daily surface albedo was due to the formation of dew on leaf surface in the morning. Surface albedo was the highest in winter (0.15) and lowest in summer (0.11). Surface albedo in spring and autumn was 0.13 and 0.12, respectively. During the growing season, surface albedo was affected by temperature and soil water content. During leaf expanding period, surface albedo was mainly affected by air temperature but not by soil water content, showing a negative linear relationship with air temperature. During expanding leaf and deciduous periods, surface albedo was affected by both air temperature and soil water content, showing a negative exponential relationship with air temperature and soil water content. However, surface albedo was decoupled with air temperature when it was greater than 24.0 ℃.

Key words: Constant charge soil colloid, Adsorption, Desorption, Lead(Ⅱ), Low-molecular-weight organic acids