PCBs对红树林沉积物中微生物及酶活性的影响

Effect of PCBs on microbial and enzyme activities in vegetated and non-vegetated mangrove sediments

研究了多氯联苯(PCBs)对沉积物及红树植物秋茄根区沉积物微生物及酶活性的影响。结果表明,种植秋茄可提高沉积物中细菌和放线菌的数量,但不能提高真菌的数量。PCBs处理可显著提高沉积物中细菌和放线菌的数量。土壤呼吸与微生物量具有相似的变化趋势。由于细菌在沉积物微生物中占有绝对的优势,因此细菌的数量是微生物多样性指数的决定性因素。与未种植红树植物的相比,种植沉积物微生物多样性指数相对较低,PCBs处理与对照相比,微生物多样性指数差异不显著。在试验过程中,未种植的PCBs处理组多酚氧化酶和过氧化物酶活性均高于对照组,表明这两种酶是沉积物PCBs污染的敏感指标,而这两种酶被报道在植物修复中与PCBs的降解有关。

Microcosms were employed to study the effect of polychlorinated biphenyls （PCBs） in vegetated （with Kandelia obovata seedlings） and non-vegetated sediment on microbial and enzyme activities. The sediment was treated with 180, 900, 1800, 2700μg· kg ^-1 of 2,2＇ ,4,4＇ - tetrachlorobiphenyl and 2,2＇ ,4,4＇ , 6,6＇ -hexachlorobiphenyl. Both vegetated and non-vegetated sediment were sampled at 1, 30, 90, 180 d and 270 d respectively following planting. Microbial enumeration, intensity of sediment respiration and microbial diversity were determined. Polyphenol oxidase and peroxidase activity were also analyzed. Results demonstrated that vegetation increased the amount of sediment bacteria and actinomycetes rather than fungi. PCB addition increased the sediment bacteria and actinomycetes population. The amount of bacteria in non-vegetated sediments was related significantly to concentrations of PCBs at day 30 and 90 with an r value of 0.974 and 0. 942 respectively. Microbial respiration intensity paralleled microbial populations over course of experiments ; increasing in the present of PCBs. Bacteria was the predominate microorganism population in sediment, and the determinant of microbial diversity. Microbial diversity of vegetated sediment were lower than that in non-vegetated sediment. In contrast, there were no significant differences in microbial diversities between PCBs treatments and the control. Polyphenol oxidase produced by sediment microorganism were stimulated by PCB addition. However, peroxidase was initially inhibited at the beginning of the experiment but increased with time. Results indicated that these two enzymes are sensitive to PCBs contamination.