干降尘中高分子有机质的组成及其来源

Composition and source of macromolecule organic matter in dry falling dust

大气降尘作为地气交换的一种重要物质,一直受到研究学者的关注。传统研究较多的是无机元素和小分子有机物,对于占干降尘有机质中相当部分的高分子有机质研究很少,因此研究降尘原样中有机大分子的组成和来源有着重要意义。用裂解-气相色谱-质谱(pyrolysis-gas chromatography–mass spectrometry,Py-GC-MS)技术对分别代表市区和郊区的五山和大学城两个采样点冬夏两季样品中的高分子有机质的组成和来源进行探讨表明,有来源于多糖类的化合物、来源于木质素类的化合物、来源于蛋白质/氨基酸类的化合物、脂肪酸、正构烷烃/烯烃以及一些不能确定其来源的化合物,其中正构烷烃/烯烃和芳香化合物是干降尘中高分子有机质的主要裂解产物。研究同时表明其来源首先取决于采样点的环境,同时也会受到气候的影响。

Many researches focus on the atmospheric falling dust regarding its important role in material cycle on Earth’s surface and the atmosphere. Inorganic elements and low-molecular-weight compounds in organic matter have been intensively studied, in contrast to little knowledge on polymeric matter of the bulk organic matter which represents a significant part of the falling dust. It is very important to study the composition and source of macromolecule organic matter in falling dust. We made analysis on four samples collected at Wushan and University City during summer and winter, using pyrolysis-gas chromatography-mass spectrometry （Py-GC-MS）. The result showed that the source of macromolecules was polysaccharides, lignin, proteins/amino acids, fatty acids, n-alkanes/alkenes and some uncertain origins. The main pyrolysates were n-Alkanes/alkenes and aromatic compounds. It was indicated that sampling site was the primary factor affected on the composition of organic matter, and another factor was seasonal variation.