Polycyclic aromatic hydrocarbons (PAHs) have high hydrophobic properties, and the adsorption of PAHs on soils makes the bioremediation of PAHs contaminated soil difficult. The dissoluble organic matter (DOM) accounts only a small part of soil organic matter, but it is key factor influencing the transformation and transportation of PAHs in soil. In order to understand the effect of DOM on the bioremediation of PAHs contaminated soil, pyrene of four rings was chosen as the target pollutant, earthworm feces or pig manure as the main source of DOM. The difference of the adsorption of pyrene onto soils before and after removal of endogenous DOM was investigated. The effects of different molecular weights, different dosages and different sources of DOM on the adsorption of pyrene by soil were studied. The results showed that: (1) the endogenous DOM could inhibit the adsorption of pyrene onto soil; the removal of the endogenous DOM might benefit the adsorption of pyrene onto soil. (2) The positive or negative role of DOM during the adsorption of organic pollutants in different soils depends on the critical value of DOM, the ratio of soil to water and its adsorption mechanism. When the ratio of soil to water was 124, the action of DOM and pyrene changed with the critical value. When the ratio of soil to water was 49, the increase of DOM concentration could promote the adsorption of pyrene. When the ratio of soil to water is 24, the increase of DOM concentration could inhibit the adsorption of pyrene. And (3) the large molecular weight component of DOM might be helpful for the dissolution of pyrene, which could lead to the inhibition of pyrene adsorption by soil. The effect of small molecular weight component of DOM was opposite. The effect of DOM with medium molecular weight on adsorption of pyrene by soil was similar to that of macromolecular DOM. The work is significant to the remediation of PAHs contaminated.%多环芳烃(PAHs)有高疏水特性,再加上土壤对PAHs的吸附作用,使得PAHs污染土壤的生物修复十分困难.水溶性有机物(Dissolved Organic Matter,DOM)虽仅占土壤有机质的很小部分,却是影响PAHs在土壤中的转化、迁移的重要因子.为了认清DOM在生物修复PAHs污染土壤中的影响作用,以四环的芘作为目标污染物,以蚯蚓粪和生猪粪作为DOM的主要来源,研究了去除内源DOM土壤和原土壤吸附PAHs的区别,探索了不同用量、不同分子量、不同来源的DOM对土壤吸附芘的影响.结果表明,(1)内源DOM抑制土壤对芘的吸附作用,去除内源DOM可促进土壤对芘的吸附.(2)不同用量DOM对土壤吸附有机污染物的作用取决于DOM的临界值质量浓度、水土比及其吸附机理.当水土比为124,DOM小于临界值时,DOM对有机物增溶起主要作用,DOM的增加抑制芘的吸附;当DOM大于临界值时,共吸附和累积吸附起主要作用,DOM促进芘的吸附.当水土比为49时,DOM质量浓度的增大能促进芘的吸附.当水土比为24时,DOM质量浓度的增大抑制芘的吸附.(3)DOM的大分子量组分质量浓度越高,对芘的增溶作用越大,更能促进芘的溶解,从而抑制土壤对芘的吸附,小分子量组分DOM的作用则相反;中分子量DOM对土壤吸附芘的影响类似于大分子量DOM.研究DOM对土壤吸附芘的影响,对于PAHs污染土壤的修复有着重要的意义.
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