北京郊区树冠穿透水中多环芳烃的污染特征与通量计算

PAHs Concentration and Flux in Canopy Throughfall in Beijing Sub-urban Area

2006年和2007年雨季,作为农村非点源污染研究的组成部分,以北京西北郊区城乡结合部的公路绿化带为采样点,对雨水和树冠穿透水中多环芳烃(PAHs)的污染特征和通量进行了研究。共采集10场降雨,分析了雨水和树冠穿透水中溶解相和颗粒相PAHs的浓度。结果显示,树冠穿透水中颗粒相∑16PAHs浓度大于雨水,而溶解相∑16PAHs浓度则小于雨水。降雨过程中树冠叶面对颗粒相PAHs具有释放作用;对溶解相PAHs则有截留作用,降雨后期截留作用的影响减弱。净通量计算结果表明,各场降雨树冠穿透水中溶解相PAHs的净通量大多为负值,颗粒相PAHs的净通量多为正值,树冠穿透水中PAHs的净通量主要来自于颗粒相PAHs。

During the raining season of 2006 and 2007, as part of the research project on the rural non-point pollution, a landscape catchment in the northwestern sub-urban area of Beijing was selected to study PAHs concentration and flux in canopy throughfall. In the sampling campaign of two years, samples in total ten rainfall events were collected. The concentrations of sixteen PAHs in both dissolved and particle phases were measured in rainwater and canopy throughfall. Measurement of PAHs in canopy throughfall water and rainwater showed that, in canopy throughfall water, the concentration of particle-bound PAHs was higher than those in rainwater, while the PAHs in dissolved phase was lower than those in rainwater. The canopy leaves have interception effect on dissolved PAHs and release effect on particle-bound PAHs. The result of net flux calculation illustrated that the net flux of dissolved PAHs was negative in most rainfall events, and the net flux of particle-bound PAHs was mostly positive. The net flux of PAHs from canopy throughfall water was dominated by PAHs in particle phase.