Abstract: By using DLY-3G air ion meter, this paper measured the air negative ion concentrations (ANIC) in the greenbelts of Guangzhou, and investigated their relations to the vegetation type, water body status, elevation above sea level, weather conditions, and human activities. The results revealed that the ANIC in Guangzhou greenbelts ranged from 103 to 3 367 ions·cm^-3, with an average of 426 ions·cm^-3 and close to those reported from Shanghai and Shenzhen. The ANIC in test greenbelts decreased in the order of bamboo plantation>Podocarpus nagi plantation > flower plantation >Eucalyptus exserta plantation > nursery ≥turf meadow > residential area, and of broadleaved stand > coniferous and broadleaved mixed stand > coniferous stand. ANIC was higher at the places near running water than near still water, and decreased significantly with increasing distance from running water. It also had an increasing trend with the increase of elevation above sea level. Sunny days had significantly higher ANIC than cloudy ones. Both the number of passers-by and that of vehicles showed significant negative correlations with ANIC.

Key words: Huolin River catchment wetland Soil organic carbon, Total nitrogen, Spatial distribution characteristics, Ecological effect