土壤和沉积物中不同形式有机质的表征

Characterization of the Different Organic Matter from Soils and Sediments

从北京通州地区3个河流沉积物和天津渤海湾地区4个土壤样品中提取胡敏酸(HA)和非水解碳(NHC),并进行了元素分析、X射线光电子能谱分析(XPS)、傅里叶变换红外光谱(FTIR)和固态13 C核磁共振(13 C NMR)等一系列定性定量的研究。结果显示:同一来源的NHC中H/C和O/C比值低于HA的H/C和O/C比值;NHC和HA表面含氧官能团的含量分别为7.6%～10.7%,40.9%～46.7%;13 C NMR和FTIR显示NHC主要由脂肪碳和芳香碳组成;从土壤中比从沉积物中提取的NHC的芳香度高。研究结果表明,与HA相比,NHC的热成熟度高,疏水性强。

The humic acid （HA） and nonhydrolyzable carbons （NHC） were isolated from three river sediment samples （1, 2, 3） from the rivers in the Tongzhou district of Beijing and four soil samples（4, 5, 6, and 7） from the surface .soils in the vicinity area of Tianjin near Bohai Bay, respectively. The isolated HA and NHC fractions were also characterized using elementary analysis, X-ray photoelectron spectroscopy （XPS）, solid state ^13C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy （^13C NMR）, and Fourier transformed infrared spectroscopy （FTIR）. The results showed that NHC had lower H/ C and O/C atomic ratios than HA from the same source. The sum of surface O-containing groups accounted for 7.6%-10. 7% and 40. 9-46.7% in NHC and HA samples, respectively. ^13C NMR and FTIR spectra of the NHC samples revealed a large contribution of alkyl carbon and aryl carbon. In addition, the NHCs isolated from soils had higher content of aromatic carbon than the NHC form river sediments. Systematic characterization showed that the NHC samples were more condensed and hydro- phobicity than the HA samples.