Air Anion Density and its Affecting Factors in Greenbelts of Changsha

Air anion has obviously biochemical effect and function, and it is beneficial to human\´s health. With the improvement of people\´s living standard, more and more people are careful about environmental quality, especially air anion density. With ALC1000 air anion meter, we measured the air anion density in the greenbelt of Changsha and investigated how it was affected by the vegetation type, water bodies, altitude, weather conditions, and human activities. These studies reveal that the air anion density in Changsha greenbelts ranges from 93 to 4168 ions.cm"3, with the average 468 ions.cm^-3, which is close to the reports from Shanghai and Shenzhen. The air anion density in the greenbelts decreases in order of bamboo grove>flowers and plants area > Martyr park > lawn > residential districts; coniferous forest > foliage forest > lawn > residential districts .The air anion is higher near running water than that near static water, and it decreases obviously with increase of distance from running water. It also has a trend, that is, it decreases with the increase of altitude. The air anion density is high in sunny days, and low in cloudy days. Both the number of passers-by and that of vehicles have negative correlations with the air anion density.