城市空气中铅在国槐树体内的积累

Lead in city air accumulated be the green tree, Sophora japonica

研究了山西省太原市、榆次市和太谷县城３个规模大小和污染程度不同的城市，主要街道两侧行道树国槐杖叶内铅内铅的含量．结果表明：国槐对街道污染空气中的铅有很强的吸收和富集作用．枝条内含铅量与街道上交通车辆密度呈正相关，最高含铅量区域在太原市火车站和五一广场一带从市区中心向郊外延伸空气污染强度减弱，国槐枝叶内含铅量也呈梯度降低趋势３个城市的国槐枝叶内含铅量与其污染强度相吻合一年四季国槐都能通过枝、叶吸收和积累铅污染物，但其含量与树木生理活动。

The city street is an artificial ecosystem, where the lead pollutant discharged from traffic vehicles seriously pollutes the street. This paper studied the variety of lead content in the body of green tree, Sophora japonica, in the walkways besides the main streets in three cities of different urban area and pollution degree in Shanxi Province. The results show that Sophora japonica is a superior antipollution tree which has strong absorption and accumulation of lead in the polluted air. The variety of lead content in its branches is Positively related to the density of traffic vehicles, with the highest content in the railway station and the public square of Taiyuan City. From the center area of Taiyuan stretching to the outskirts, the lead air pollution and its content within tree body tend to decrease. The lead contents in the tree they markedly differentiate in these three cities, and coincide with their pollution degree. In whole year, the tree can absorb and accumulate lead pollutants through branches and leaves; but variety of the content is closely related to the Physiological action and growing cycle of the trees.