兰州市大气飘尘的有机地球化学研究--Ⅱ酮和醇脂类化合物的组成和分布特征

首次对兰州市大气飘尘中酮和醇脂类化合物进行了分析和研究。结果表明，兰州市大气飘尘中正烷基-２-酮和直链烷基醇的浓度分别为２０～２７０ｎｇ·ｍ－３和５２０～９１０ｎｇｍ－３，并表现为３月份高于７月和８月份，这与兰州市特殊的地形和气候条件有关；其分布特征指示了它们来自人为活动、微生物和现代高等植物，而且它们在这３种来源中所占的比例分别为２．８%～１９．７%、１５．４%～３４．６%和５０．３%～８１．８%。甾醇化合物的浓度很低，它们由现代生物所提供。丰富的Ｃ_１８类异戊二烯酮化合物的存在，反映了大气飘尘中有机质在大气氧化过程中已经被改造。

Organic Geochemical Studies on Airborne Particulates in Lanzhou City- Ⅱ·Composition and distribution of ketone and alcohol lipid compounds

In this paper, ketone and alcohol lipid compounds in airborne particulates from Lanzhou city have been analy sed and studied.The concent rations of n-alkan-2-ones and n-alkanols are 20-270 ng.m-3 and 520-910 ng.m-3, respectively.They have higher concent rations in March than in July and August, which is related to special topog raphy and climate of Lanzhou area.The dist ribution of these compounds indicates that they are derived anthropogenic activity, microbes and modern higher plants and the assignment of their sources is 2.8 %～ 19.7 % fo r anthropogenic acitivity, 15.4 %～ 34.6 % for microbes and 50.3 %～ 81.8 % for modern higher plant s.Sterols are present at low concent rations,which are provided by modern organisms.The presence of abundant C₁₈ isoprenoid ketone shows that org anic mat ter in airborne particulates f rom Lanzhou city is transformed in the oxidizing process of the atmosphre.