苯并[a]芘累积污染对土壤微生物群落功能多样性的影响

Effects of cumulative benzo( a) pyrene pollution on functional diversity of microbial community in soil

本文采用低剂量叠加的方式模拟苯并[a]芘(Benzo(a)pyrene,Ba P)在实际土壤中的累积过程,利用Biolog-ECO方法研究Ba P不同污染方式对土壤微生物群落功能的影响,以期揭示Ba P累积污染对土壤微生物群落功能多样性的影响.结果表明,在累积和一次污染方式下,土壤Ba P可提取态和有效态含量随土壤培养时间的延长而降低,前期(1—28 d)下降速率较快,后期(28—56 d)下降速率减缓.土壤微生物代谢活性AWCD值在培养初期(1 d)表现出L>CK-Y>Y>CK-L的规律,培养7 d表现为Y>CK-Y>CK-L>L,而后(8—56 d)各处理的AWCD值表现与培养7 d的规律一致.微生物群落物种丰富度指数和常见物种优势度指数的变化趋势与AWCD值变化规律一致.累积污染处理在土壤培养过程中先促进(1 d)后抑制(7—56 d)了土壤微生物群落功能多样性;一次污染处理与之相反,先抑制(1 d)后刺激(7—56 d)了土壤微生物群落功能多样性.累积污染处理的微生物代谢活性和多样性指数与Ba P含量的相关性大于一次污染.累积污染更能反映Ba P在土壤中的真实生物毒性.

To reveal the impact of accumulated pollution of Benzo（ a） pyrene（ Ba P） on the functional diversity of soil microbial community,Ba P was added to soil by low-dose superposition method to simulate the cumulative pollution of Ba P in natural soil,and the effects of different Ba P pollution on microbial community functions in soil was investigated by the Biolog-ECO method. The results showed that the extractble and available Ba P contents in soil declined quickly in the first 28 days and then decreased slowly from 28 to 56 days under the one-time and accumulated pollution conditions. AWCD,reflecting the soil microbial metabolic activity,followed the order of LCK-YYCK-L at the beginning of incubation period（ 1 d）,and Y CK-Y CK-LL on the 7th day. Then the order of AWCD during the rest of incubation period（ 8—56 d） was the same as that on the 7th day. Moreover,Shannon and Simpson index showed similar patterns as the AWCD under the onetime and accumulated pollution conditions. Compared with CK-L and CK-Y,accumulated pollutionpromoted the functional diversity（ 1 d） and then inhibited microbial activities（ 7—56 d）. One-time pollution treatment inhibited the functional diversity（ 1 d） and then stimulated microbial activities（ 7—56 d）. Besides,there was higher positive correlation between the contents of Ba P and microbial community functional diversity index in the accumulated pollution soil than in one-time pollution soil.The low-dose superposition method is more appropriate to reflect environmental risk of Ba P in soil.