北京市六种针叶树叶面附着颗粒物的理化特征

对北京市6种针叶树叶面颗粒物附着密度、叶表面微形态、颗粒物矿物与元素组成的研究结果表明：同一树种叶面颗粒物附着密度随大气颗粒物浓度增加而增大；同一地点不同树种叶面颗粒物附着密度存在很大差异，圆柏、侧柏颗粒物附着密度最高，其次为雪松、白皮松，油松、云杉最低；受地面扬尘影响，低矮叶片较高处叶片颗粒物附着密度大；受降雨和新生叶片稀释影响，夏季颗粒物附着密度小于冬季.叶表面粗糙程度越大，颗粒物附着密度越高.SiO₂、CaCO₃、CaMg(CO₃)₂、NaCl、2CaSO₄·H₂O、CaSO₄·2H₂O、Fe₂O₃ 7种主要矿物占叶面颗粒物总质量的10%～30%，其中,SiO₂含量最高，其次为CaMg(CO₃)₂ 、CaSO₄·2H₂O和CaCO₃.此外，还含有蒙脱石、伊利石、高岭石等粘土矿物及长石.21种测定元素占叶面颗粒物总质量的16%～37%，其中Ca、Al、Fe、Mg、K、Na、S 7种元素占测定元素总质量的97%以上，其它痕量污染元素含量很少，并且受采样地点和树种影响较小.

Physico-chemical characteristics of ambient particles settling upon leaf surface of six conifers in Beijing

The study on the density of ambient particles settling upon the leaf surface of six conifers in Beijing, the micro-configurations of the leaf surface, and the mineral and element compositions of the particles showed that at the same sites and for the same tree species, the density of the particles settling upon leaf surface increased with increasing ambient pollution, but for various tree species, it differed significantly, with the sequence of Sabina chinensis and Platycladus orientalis > Cedrus deodara and Pinus bungeana > P. tabulaeformis and Picea koraiensis. Due to the effects of road dust, low height leaf had a larger density of particles. The density of the particles was smaller in summer than in winter because of the rainfall and new leaf growth. The larger the roughness of leaf surface, the larger density of the particles was. In the particles, the overall content of SiO2, CaCO3, CaMg(CO3,), NaCl, 2CaSO4 . H2O, CaSO4 . 2H2O and Fe2O3 was about 10%-30%, and the main minerals were montmorillonite, illite, kaolinite and feldspar. The total content of 21 test elements in the particles reached 16%-37%, among which, Ca, Al, Fe, Mg, K, Na and S occupied 97% or more, while the others were very few and less affected by sampling sites and tree species.