中文摘要：

选择一口开采约20a的废弃油井,在距离井口0.5,1.5,3.5,5.5和7.5 m处进行多点采样,应用元素分析、傅里叶变换红外光谱和固态13C核磁共振方法,研究了长期不同程度石油污染土壤中胡敏酸的结构特征。结果表明：随与油井口距离的减小,胡敏酸的C/H,O/C和（N＋O）/C原子比值分别由0.74,0.41和0.45增加到0.80,0.83和0.88;红外光谱分析显示,胡敏酸的2 921,2 851,1 454 cm^-1吸收峰相对强度下降,2 921/1 600比值由0.22减少到0.11;固态13C核磁共振分析显示,胡敏酸中烷基C的相对含量由49.9%下降到30.9%,而烷氧C、芳香C和羧基C的相对含量分别由20.1%,13.1%和14.3%增加到28.0%18.8%和19.3%。上述结果说明,随石油含量增加,胡敏酸的脂族性和疏水性降低,而芳香性和极性增强,其分子结构变得老化。为了促进受石油污染土壤的修复,有必要采取适当措施使其中老化的胡敏酸得以更新和活化。

英文摘要：

Petroleum contamination in soil decreases with the increase in the distance of soil to the drilling well. Accordingly, an abandoned petroleum well which had been exploited for about twenty years in Songyuan city of Jilin Province, China, was selected to investigate the structural characteristics of soil humic acids （HAs） under different petroleum contamination levels. Surface （0-20 cm） soil samples were collected at 0. 5, 1.5, 3.5, 5. 5 and 7. 5 m deep from well head, and the petroleum contents were respectively 153.3, 148. 4, 129.2, 50.5 and 5.62 g · kg^-1. HAs were extracted with 0. 1 mol · L^-1 NaOH and 0.1 mol · L^-1 Na4 P2O7 and were characterized with elemental analysis, Fourier transformed infrared （FTIR） spectroscopy and solid-state ^13C cross polarization magic angle spinning nuclear magnetic resonance （^13 C CPMAS NMR） spectroscopy. Results showed that the atomic C/H, O/C and （N＋O）/C ratios of HAs increased from 0. 74, 0. 41 and 0. 45 for 7.5 m to 0. 80, 0. 83 and 0. 88 for 0. 5 m, respectively. The relative intensity of the peaks assigned to aliphatie carbon （2 921, 2 851 and 1 454 cm^-1） in the FTIR spectra gradually decreased with increasing contamination levels, while that of the peak assigned to aromatic C（1 600 cm^-1 ） increased, and the calculated absorption intensity ratio of 2 921 to 1 600 cm^-1 （2 921/1 600） declined from 0. 22 for 7. 5 m to 0. 11 for 0. 5 m. The solid-state ^13C NMR data suggested that the relative content of alkyl C（0-50 ppm ） decreased from 49.9% for 7.5m to 30. 9% for 0. 5 m, while that of O-alkyl C（50-110 ppm）, aromatic C（110-160 ppm） and carboxyl C（160-190 ppm） increased respectively from 20. 1 %, 13.1 % and 14. 3 % to 28. 0%, 18.8% and 19.3 %. These results showed substantial chemical, structural, and molecular differences among these HAs. The aliphaticity and hydrophobicity of HAs decreased while aromaticity and polarity increased with the increase in petroleum content. Namely, HAs tended to become aged in molecular