生物强化和生物刺激对土壤中PAHs降解的影响

采用生物强化(农田土中添加PAHs污染土或污泥)和生物刺激(PAHs污染土中添加(NH4)2HPO4)2种措施,研究了土壤中13种PAHs的降解及CO2的释放量.结果显示,农田土壤中的微生物对2~5环的PAHs都有较强的降解能力,添加污染土显著增强了对5环PAHs的降解,表明污染土中的微生物对高环PAHs的降解能力更强;添加污泥对促进PAHs降解的作用不明显,可能是好氧培养条件不适合厌氧菌的生长.添加N、P营养盐可显著提高污染土中3~4环PAHs的降解,但5环PAHs在添加和未添加N、P中的降解率始终较低,均小于10%.CO2的释放呈现先增加再降低,再略微增加直至平稳的过程,且与PAHs的降解高度响应,说明PAHs的降解与微生物活性密切相关.

Effects of bioaugmentation and biostimulation on PAHs degradation in soil

Degradation of 13 PAHs in clean agricultural soil and CO_2 emission was studied with the measures of (I) bioaugmentation, by adding aged PAH-polluted soil or PAH- polluted sludge; (ii) biostimulation, by introducing nutrition source of (NH_4)_2HPO_4. Meanwhile, the release of CO_2 was also determined. 2～5-ring PAHs were well degraded in agricultural soil confirming the degradation capacity of indigenous microorganisms. Additionally, the degradation of 5-ring PAHs was improved significantly after introducing of PAH-polluted soil, which indicated that the microbes in polluted soil were more powerful than those in clean agricultural soil in degrading high-molecular-weight PAHs. In contrast, no significant improvement in PAHs degradation occurred with addition of polluted sludge, possibly due to the aerobic condition in the experiment. With addition of nutrition sources ((NH_4)_2HPO_4), the degradation of PAHs in aged soil increased significantly, except for the 5-ring PAHs with a degradation rate less than 10%. The release of CO_2 during the incubation experienced an initial of rapid increase followed by a sharp decrease, then stabilized after a slight increase, highly corresponding to PAHs degradation, which indicated a close relationship between PAHs degradation process and microbial activity.