西安城区植被净化大气污染物的时间变化

基于植被净化大气的机理,分析了净化量与污染物浓度、叶面指数等的关系,系统收集1991～2000年西安市TSP、SO2、NOX月均浓度,结合实验观察,得出:①西安市针叶林、阔叶林TSP、SO2、NOX净化量计算的经验公式。②TSP、SO2、NOX浓度在年内变化呈U字型,叶面指数年内变化呈倒U字型,二者变化不同步,植被对污染物净化量的年内变化整体也呈倒U字型。③1991～2000年TSP、SO2、NOX浓度的年际变化整体都是下降的,其中都有波动;10年来的植被覆盖率基本不变;植被对TSP、SO2、NOX的净化量与其浓度的年际变化同步,即成正比关系。

Variation of atmosphere purification by vegetation among different time in a year in Urban area of Xi'an

Based on mechanism of atmosphere purification by vegetation, the relations between amount of purification and pollution concentration, leaf area index were analyzed. The average monthly concentrations of TSP, SO2 and NOX in Xi'an city from 1991 to 2000 were used in the analyses in combination with experimental observations. The following results were obtained: 1) Empirical formulas for calculating amounts of purified TSP, SO2 and NOX for coniferous and broad-leaved forests; 2) The changes of TSP, SO2 and NOX concentrations withina year were in a U-formed curve, and the changes of leave area index was in an inversed U curve; 3) The overall trends of yearly changes of TSP, SO2 and NOX concentrations were declining during 1991 to 2000, but all with fluctuations; the vegetation coverage was basically unchanged; the changes in amount of purified TSP, SO2 and NOX were synchronous with their concentrations, in a positive correlations.