苯并芘[a]不同污染方式对黄褐土微生物区系的影响

为研究苯并[a]芘(B[a]P)在土壤中逐步累积后对土壤微生物区系的影响,试验采用低剂量叠加的方式模拟B[a]P在黄褐土中的累积过程,研究B[a]P不同污染方式对土壤B[a]P含量和微生物可培养种群数量的影响。结果表明:在B[a]P累积和一次污染方式下,土壤B[a]P可提取态和有效含量随培养时间的延长而降低,培养前期(1~28 d)下降速率较快,后期(28~56 d)下降速率减缓。B[a]P累积污染在整个培养期内显著地增加了土壤可培养细菌的数量,降低了真菌和放线菌的数量;一次污染在初期降低了可培养细菌和放线菌的数量,增加了真菌的数量。B[a]P累积污染对土壤微生物数量的抑制率为放线菌真菌细菌;一次污染对土壤微生物数量的抑制率为放线菌细菌真菌。放线菌对土壤B[a]P污染最为敏感,且与土壤B[a]P含量的相关性高于细菌和真菌,可作为多环芳烃类污染物污染土壤的生物学指标。累积污染以低剂量叠加方式研究了土壤微生物区系对B[a]P污染的响应,反映了B[a]P在实际土壤中的环境风险。

Effects of benzo[a]pyrene pollution over one-time and cumulative patterns on microbial flora in yellow-cinnamon soil

This study examined the effects of accumulated benzo[a]pyrene(B[a]P) on soil microorganisms. The bioavailability of B[a]P and its influence on microbial populations in yellow-cinnamon soil were investigated using one-time and accumulated pollution methods under simulated conditions. The results showed that the extractable and available B[a]P content in soil declined quickly in the first 28 days, then decreased slowly from 28 to 56 days in each of the two pollution conditions. During the incubation period, the number of soil bacteria significantly increased, while that of fungi and actinomycetes decreased in the accumulated pollution condition. However, decreased populations of bacteria and actinomycetes and an increased number of fungi were observed in the initial stage of the incubation period in the one-time pollution condition. The inhibition rates of accumulated pollution on the activities of different soil microbial species were actinomycetes > fungi > bacteria. For one-time pollution, the inhibition rates were actinomycetes > bacteria > fungi. In conclusion, actinomycetes were the most sensitive of the three microorganisms to B[a]P pollution, and their population size was more correlated with soil B[a]P content than that of either bacteria or fungi. Therefore, actinomycetes could be used as biological indicators for polycyclic aromatic hydrocarbon-contaminated soil. In this study, responses of soil microbial flora to accumulated B[a]P pollution were investigated using a low dose accumulation method, which was an optimum approach that reflected the environmental risk of B[a]P under natural soil conditions.