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景观水体是湿地公园、城市旅游景点的重要组成部分,然而城市景观水体大部分是封闭或者是半封闭状态[1],其自净能力弱,环境容量小,生态系统相对简单[2],水质稳定性差,易发生富营养化[3]。由于地表径流、无组织排放污水的流入以及内源性污染物的释放,导致景观水体藻类大量生长,甚至出现黑臭,大大降低了其景观价值[4]。因此,如何修复治理污染景观水体,使其水质长期维持稳定,成为生态环保领域急需解决的环境问题。
污染景观水体的修复方法主要包括物理、化学、生物生态处理法,如曝气、化学药剂或微生物菌剂的投加、水生植被恢复等[5]。由于化学药剂的使用成本高,容易产生二次污染,而投加微生物菌剂的治理效果不稳定,且存在一定生态风险[6],因此,曝气增氧和水生植物恢复成为污染水体修复常用措施。
尽管曝气增氧是水体污染修复的一个重要手段,但是传统鼓风曝气产生的气泡大、氧传质效率低、能耗大[7]。近年来,微纳米曝气技术因产生的气泡体积小、比表面积大、在水中停留时间长、氧传质效率高、能产生活性氧等优点,而备受关注[8]。苦草是我国地表水体典型沉水植物,其繁殖速度快,根系较发达,对天然水体水质净化,维持水生态平衡发挥重要作用,是地表污染水体生态修复优先选择的物种[9]。已有微纳米曝气应用在生物膜污水处理、微纳米气泡浮选、“微纳米曝气-臭氧”耦合处理技术在生活污水、工业废水、地表水体及地下水污染修复等方面的研究报道[10-13],但微纳米曝气联合水生植物修复城市污染景观水体的研究处于起步阶段,尚未探明微纳米曝气联合植被恢复作用对污染景观水体微生态结构的调控机理。
鉴于此,本研究采用微纳米曝气联合苦草 (micro-nano aeration combined with Vallisneria natans,MAVS) 对合肥湿地公园污染景观水体进行修复治理,考察COD、NH4+-N、TP、TN的处理效果及微生物种群结构的动态变化规律,旨在为MAVS技术修复污染城市景观水体提供理论依据和技术支撑。
微纳米曝气联合苦草对污染景观水体的修复效果及对微生物群落结构的影响
Effects of micro-nano aeration combined with Vallisneria natans on the remediation of polluted landscape water bodies and microbial community structure
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摘要: 为探索微纳米曝气联合苦草 (micro-nano aeration combined with Vallisneria natans,MAVS) 对污染水体修复效果及微生物种群调控机理,以合肥国家湿地公园一处污染水体为修复对象并结合示范工程实验,考察了MAVS对景观水体修复效果及该水体水质及微生物种群结构的动态变化规律。结果表明:经过MAVS修复后,污染景观水体水质得到了明显改善,水体DO逐步提升,COD、NH4+-N、TN、TP分别降低了50%、85%、75%和75%左右;底泥微生物群落结构多样性随修复进程的推进而不断增加,而优势微生物种群结构组成保持相对稳定,但其丰度随修复进程而变化;在门分类水平上,优势菌门为Proteobacteria、Bacteroidetes、Acidobacteria和Chloroflexi,其中Proteobacteria、Bacteroidetes的丰度随修复过程的进行而下降,而Acidobacteria、Chloroflexi的丰度逐步增加;在属分类水平上,优势菌属为Rhodocyclus_uncultured、Xanthomonadales Incertae Sedis_uncultured、Alcaligenes_uncultured和Bacteroidetes vadinHA17_norank,其丰度随修复过程的进行而下降,修复进程停止后丰度逐渐增加;随着修复过程的进行,污染景观水体底泥优势微生物群落丰度呈现出与COD相同、DO相反的变化趋势,但在时间上存在一定的滞后性。由此可以看出,修复水体微生物群落结构随修复进程、水质特性的变化而变化,COD是驱动微生物群落结构及丰度变化的最大贡献者,同时DO、TP也对其变化产生一定影响。微纳米曝气联合苦草能有效修复污染水体,调控水体底泥微生物种群结构,具有良好的推广应用价值。Abstract: To explore the effect of micro-nano aeration combined with Vallisneria natans (MAVS) on the remediation of polluted water bodies and the mechanism of microbial population regulation, a polluted water body in Hefei National Wetland Park was used as a remediation object, and the restoration effect of landscape water body by MAVS and the dynamic change rule of water quality and microbial population structure of this water body were investigated with the demonstration project experiment. The results showed that after MAVS remediation, the water quality of the polluted landscape water body was significantly improved, its DO increased gradually, and the COD, NH4+-N, TN, and TP decreased by about 50%, 85%, 75%, and 75%, respectively; the structural diversity of the substrate microbial community increased with the remediation process, and the structural composition of the dominant microbial population remained relatively stable, but its abundance changed with the remediation process. At the phylum classification level, the dominant phyla were Proteobacteria, Bacteroidetes, Acidobacteria, and Chloroflexi, of which the abundance of Proteobacteria and Bacteroidetes decreased with the restoration process, while the abundance of Acidobacteria and Chloroflexi increased gradually; at the genus classification level, the dominant genera were Rhodocyclus_uncultured, Xanthomonadales Incertae Sedis_uncultured, Alcaligenes uncultured and Bacteroidetes vadinHA17_norank, their abundance decreased with the remediation process, and gradually increased after the remediation process stopped. With the remediation process, the abundance of the dominant microbial community in the substrate of polluted landscape water bodies showed the same trend as COD and the opposite trend of DO, but it had a certain time lag. It can be seen that the microbial community structure of the remediated water body changed with the remediation process and water quality characteristics, and COD was the largest contributor to the change of microbial community structure and abundance, DO and TP also had some influence on this change. The micro-nano aeration combined with Vallisneria natans could effectively remediate polluted water bodies and regulate the microbial population structure of the water body substrate, which has good value of popularization and application.
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表 1 景观水体初始水质
Table 1. Initial water quality of landscape water body
采样点 NH4+-N/(mg·L−1) TP/(mg·L−1) COD/(mg·L−1) TN/(mg·L−1) DO/(mg·L−1) A1 0.80±0.006 0.34±0.004 28.26 1.04±0.065 3.30±0.25 A2 0.84±0.023 0.38±0.047 33.76 2±0.032 3.50±0.18 A3 0.87±0.006 0.40±0.009 28.94 2.02±0.041 2.35±0.30 A4 1.01±0.005 0.52±0.14 30.78 2.07±0.057 2.97±0.26 Ⅲ类水标准
(GB 3838-2002)1.0 0.2 20 1.0 5 表 2 微生物群落OTUs及相关指数的变化
Table 2. Changes of OTUs and related indices of microbial community
月份 OUTs Chao指数 覆盖度 Shannon指数 3 2 366.67 2 919 0.969 0 5.95 6 2 189.33 2 779.67 0.971 1 5.81 9 2 263.67 2 835 0.971 1 6.09 10 2 382.67 3 077.33 0.967 2 6.22 12 2 642.67 3 406 0.962 8 6.22 表 3 不同时间段微生物群落在门水平上相对丰度
Table 3. Relative abundance of microbial communities in different time periods (phylum)
菌门 相对丰度/% 3月 6月 9月 10月 12月 Acidobacteria 9.51 10.39 9.59 16.21 7.30 Actinobacteria 2.17 2.37 2.43 2.98 5.72 Bacteroidetes 9.95 3.71 3.22 2.19 3.37 Chloroflexi 6.14 9.49 13.98 11.43 17.90 Firmicutes 3.74 12.74 2.73 5.43 5.40 Ignavibacteriae 2.30 1.34 1.55 1.46 0.97 Nitrospinae 2.38 1.94 0.97 0.80 1.84 Nitrospirae 2.27 2.83 6.00 5.45 2.68 Proteobacteria 53.54 44.65 46.86 37.13 45.47 Verrucomicrobia 1.47 1.88 1.16 0.77 1.66 Others 6.52 8.66 11.53 16.16 7.68 表 4 不同时间段微生物群落在属水平上的变化
Table 4. Changes of microbial community abundance at genus level in different time periods
菌属 相对丰度/% 3月 6月 9月 10月 12月 Rhodocyclus_uncultured 8.81 5.06 3.20 1.42 6.44 Xanthomonadales Incertae
Sedis_uncultured8.50 9.00 6.25 2.37 7.49 Crenothrix 0.79 0.89 0.81 0.29 1.19 Syntrophaceae_uncultured 0.71 0.80 1.24 1.49 0.88 Gaiellales_norank 0.30 0.55 0.35 0.48 1.18 Alcaligenaceae_uncultured 2.94 3.90 2.60 1.23 2.82 Clostridium sensu stricto 13 2.32 1.83 0.06 0.10 0.09 Bacteroidetes vadinHA17_norank 2.73 1.28 1.38 0.77 1.06 Lentimicrobiaceae_norank 2.40 0.42 0.21 0.18 0.32 -
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