周丛生物存在下不同水层氧化还原带的分布及其与微生物的关联

目前人工水草、弹性填料等多种载体广泛用于地表水体净化,通过载体表面富集的周丛生物去除污染物达到净化效果.尤其在周丛生物存在情况下,不同水层的氧化还原带分布情况与污染物的去除有着直接或间接的关系,因此,研究周丛生物存在下不同水层氧化还原带的分布及其微生物特征具有重要的实际意义.在模拟的水柱装置中,加入玄武湖采集的富营养化水,再悬挂弹性填料富集周丛生物,待周丛生物生长达到稳定期之后,监测不同水层氧化还原因子及其微生物.结果表明,周丛生物作用下,水柱中不同水层自上而下依次出现5条氧化还原带,周丛生物在每个带所利用的最终电子受体分别为O2、NO-3、Fe3+、CO2和SO2-4,依次称为氧还原带、NO-3还原带、铁还原带、产甲烷带和SO2-4还原带;各带的标志性物质DO、NO-2、Fe2+、HCO-3和硫化物的最高值分别为11.290、4.950、38.326、120.000和12.180 mg·L-1.通过Biolog技术监测微生物特征显示:不同水层对应的周丛生物其组成、代谢活性、碳源利用能力存在显著差异,由此造成了不同水层氧化还原带的分布.不同水层氧化还原带分布及其微生物特征的研究,为揭示周丛生物净化不同深度水体水质提供了科学解释,也为发展高效的基于周丛生物净化水质的技术提供了理论依据.

Distribution of Redox Zone at Different Water Layers in the Presence of Periphyton and the Responsible Microorganisms

So far, many types of carriers (such as artificial mat, industrial soft carriers) have been widely used in removing pollutants, purifying water quality via the periphyton attached on the surface of these carriers. In the presence of periphyton, the distribution of redox zone at different water layers is directly or indirectly associated with the removal rate of pollutants. Therefore, it is more practically significant to study the distribution of redox zone at different water layers and the microbial diversity in the presence of periphyton. In this study, the pilot experiment was performed in a simulated water column bioreactor. Firstly, the eutrophic water collected from XuanWu Lake was added into the simulated water column bioreactor. The industrial soft carriers were then suspended into the water column in order to enhance the growth of periphyton. After periphyton gained a steady growth state, the oxidation reduction zones (redox zones) and the responsible microorganisms at different water layers were monitored. The results showed that five sequent redox zones (i.e. oxygen reduction, nitrate reduction, iron reduction, methanogenic and sulfate reduction zones, respectively) appeared in different water layers from top-down in the presence of periphyton and their responsible terminal electron acceptors were O₂, NO₃^-, Fe³⁺, CO₂ and SO₄^2- respectively. The indicators of the different zones were DO, NO₂^-, Fe²⁺, HCO₃^- and sulfide, and the highest concentrations were 11.290 mg ·L^-1, 4.950 mg ·L^-1, 38.326 mg ·L^-1, 120.000 mg ·L^-1 and 12.180 mg ·L^-1, respectively. The results of microbiological characteristics tested by Biolog EcoPlate^TM technology revealed that there were significant differences in the composition, metabolic activity, carbon utilization of periphyton at different water layers, causing the difference in the distribution of redox zones at different water layers. These findings implies that study on the distribution of redox zones and microbiological characteristics in the presence of periphyton provides a better understanding that periphyton is capable of improving water quality at different layer, and also provides some theoretical basis for the development of technology for purifying water quality based on periphyton.