崇明岛东部不同年代围垦区土壤有机质组成变化研究

Four typical soil cores(CM2, CM4, CM5, CM6)in reclamation areas built from 1960s to 1990s in the Eastern Chongming Island, were selected in this study for deciphering the stability nature of organic matters in buried salt marsh strata. A amount of different kinds of pyrolysis products in soil organic matter(SOM)were determined by pyrolysis gas chromatography-mass spectrometry(Py-GC-MS). The variation of SOM composition in the buried salt marsh strata was obtained at molecular level and the stability of the SOM from different-time reclamation areas was studied. The results showed there were 53, 80, 47 and 21 kinds of pyrolysis products of organic matter for CM2, CM4, CM5, CM6, respectively. The dominant kinds of the pyrolysis products in all SOM are as aliphatic compounds (alkanes, olefins, fatty acids, etc.), aromatic compounds (aromatic, polyaromatic, etc.), heterocyclic compounds, phenolic compounds, polysaccharides, N-compounds and S-compounds. Amounts of aliphatic compounds, N-compounds, phenolic compounds and other components with relatively high chemical stability in the pyrolysis products of SOM increased with time from CM6, CM5, CM4 to CM2. The increase in the content of heterocyclic compounds and the content ratio of polyaromatic to aromatic indicated that refractory components accumulated and the chemical stability of SOM was enhanced with time.