长期石油污染土壤腐殖质组成的研究

Humus Composition of Petroleum Hydrocarbon-Contaminated Soil

选择1口开采约20 a的废弃油井,在距离井口0.5、1.5、2.5、3.5、4.5、5.5、6.5、7.5和10.5 m处进行多点采样,应用腐殖质组成修改法和Simon-Kumada法,分别研究了上述长期不同程度石油污染土壤的全土及不同结合形态腐殖质组成.结果表明,土壤石油含量随距井口距离加大而降低,最远处（10.5 m）和最近处（0.5 m）分别为0.08 g/kg和153.3 g/kg.随石油含量增加,土壤有机碳和水溶性有机碳含量增加;全土腐殖质中,可提取腐殖质（HE）含量和胡敏酸（HA）含量下降而胡敏素（HM）含量增加,HA/HE的百分比（PQ 72.0%-8.05%）下降而HM/HE（31.4-76.7）增加;不同结合形态腐殖质中,松、稳结合态腐殖质（HI、HII）的含量呈下降趋势而紧结合态腐殖质（HIII）的含量增加,HI/HII（0.19-0.39）呈增加趋势,而HI/HIII（0.032-0.003）和HII/HIII（0.096-0.009）下降,HI、HII的PQ（3.21%-1.42%、58.1%-35.5%）也下降,并且HI的PQ变化幅度小于HII;水溶性有机质（WSOM）的色调系数（Δlogk）下降而HA则变化不大.以上结果说明,随石油污染程度增加,土壤HM的形成增强而HA形成减弱,对HA形成的影响主要表现为对稳结合态HA形成的抑制作用,WSOM分子结构趋于复杂而HA没有明显变化.

An abandoned petroleum well which had been exploited for about twenty years in Songyuan city of Jilin Province, China, was selected to study the compositions and characteristics of soil humus using revised humus composition method and Simon-Kumada method. Soil samples were collected at 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5 and 10.5 m apart from the well head. Results show that the petroleum contents increase from 0.08 g/kg （10.5 m to the well head） to 153.3 g/kg （0.5 m to the well head）. With the increase in petroleum content, the contents of soil organic carbon and water soluble organic carbon increase ; for total soil humus, the contents of extractable humus （HE） and humic acid （HA） decrease whereas that of humin （HM） increase ; the percentage of HA/HE （ PQ 72.0 % -8.05 % ） decrease and HM/HE ratio （31.4-76.7） increase; for different combined humus, the contents of loosely combined humus （HI） and stably combined humus （HII） have a decrease tendency while that of tightly combined humus （HIII） increase; the HI/HII ratio （0.19-0.39） shows an increase tendency, whereas HI/HIII ratio （0.032-0.003） and HII/HIII ratio （0.096-0.009） decrease; the PQs of HI （3.21%-1.42%） and HIII （58.1%-35.5%） also decrease, and the range of PQ change is less in HI than in HII; the color coefficient （△logk） of water soluble organic matter （WSOM） decreases, whereas no obvious change for HA. The above results indicate that petroleum hydrocarbon promotes the formation of HM but not HA. The decrease in HA is mainly due to the restraining effect of petroleum hydrocarbon on the formation of stably combined HA. Petroleum hydrocarbon leads molecular structure of WSOM more complex but no effect on molecular structure of HA.