清潩河是典型的基流匮乏型河流,水生态环境质量空间差异明显,为探究浮游生物群落结构特征及其与水环境的关联性,于2021年7月在清潩河(许昌段)开展浮游生物及环境因子调查,基于综合水质标识指数及生物多样性指数分析水体污染程度,并利用典范对应分析法分析干流与支流河段浮游生物群落结构的关键影响因子.结果显示:本次调查共检出浮游植物8门204种,群落结构为绿藻-硅藻-蓝藻型;检出浮游动物4 门88种,群落结构以轮虫、原生动物为主;浮游生物多样性指数及综合水质标识指数均显示清潩河(许昌段)水质为轻度污染,但浮游生物优势种显示其有富营养化可能.典范对应分析结果显示,不同河段影响浮游生物优势种密度的关键影响因子有所不同:干流及支流浮游植物群落结构分别受WT、TP、DO、NO3--N和CODCr、TN、NO2-N、原生动物的影响,干流及支流浮游动物群落结构分别受TSS、甲藻和NO2--N、CODCr、金藻、隐藻的影响.

There are a number of small and medium-sized rivers throughout China, which are the closest to humans. But they are also affected by man-made transformation and production and life activities and show more obvious ecological degradation. Taking the Xuchang section of the Qingyi River as the study area, a mass-balance food web model was established with "Ecopath with Ecosim" according to the data of aquatic organisms collected in the summer and autumn of 2021. The achieved results reveal that the Qingyi River ecosystem mainly consists of five integrated nutrient levels (1.00-3.29), and due to the low transfer efficiency of trophic levels I and II, the energy flow to the higher nutrient level was seriously hindered, and the conversion efficiency of the whole system was only 1.08% and 1.82%. The mixed trophic impacts did not alter in summer and autumn, and predators except Culter alburnus exhibited a strong inhibitory effect on the bait organisms. A comprehensive analysis of multiple indicators, including parameters close to maturity, resilience and stability of the system, indicate that the total flow rates of the Qingyi River ecosystem were 2 571.06 and 1 472.58 t·km-2 in summer and autumn, respectively, and the size of the ecosystem in summer is greater than that in autumn and Finn′s cycling index (FCI) and Finn′s mean path length (FML) also revealed that the ecosystem maturity and stability in summer were superior to those in autumn. Finally, according to the food web model, three key functional groups at various nutrient levels in the Qingyi River ecosystem have been selected as phytoplanktons, molluscs, and Culter albus, while maintaining the appropriate requirements of key functional habitats and growth habits, the pertinent suggestions for restoring the ecosystem, such as limiting the growth of dominant phytoplankton species, increasing mollusk predator pressure, and restoring the Culter alburnus population are presented. The findings of this study could provide decision-making basis and scientific support for the ecological restoration of the Qingyi River and similar rivers.

为明确生态修复类型河流的微生物群落结构、功能及其影响因素,以许昌市清潩河为例,采用高通量测序的方法研究生态修复措施对河流水体和沉积物微生物群落结构的影响,并在此基础上分析碳氮硫功能菌群在生态修复措施中的净化作用及水体病原菌分布状况.结果表明:在人类干扰较少的河段,近自然河岸带对陆源污染起着较好的拦截效果,生态滤坝设施的截留和复氧能力有助于河流对化学需氧量(COD)的去除;城区段河流受人类活动影响水质变化较大,生态修复措施净化效果不明显;城郊段人类干扰较少,河流自净能力提升,总磷(TP)、氨氮(NH4+-N)等指标逐渐恢复原有水平.清潩河沉积物中微生物多样性和丰富度均高于水体,且变形菌门(Proteobacteria)是沉积物和水体中的优势物种.部分河段参与氮循环的蓝藻菌门(Cyanobacteria)相对丰度达到 4.7%,说明清潩河仍存在富营养化河段.清潩河水体中相对丰度最高的致病菌群为不动杆菌(Acinetobacter),而沉积物中相对丰度最高的致病菌群为梭状芽孢杆菌属(Clostridium)、黄杆菌属(Flavobacterium)和拟杆菌门(Bacteroidetes),其中拟杆菌门在城区段相对丰度最高.Spearman相关性分析表明,水体中微生物多样性与温度、pH、COD有显著相关性(P<0.05),城郊段沉积物中微生物群落结构的主要影响因子为NH4+-N、总氮(TN)和TP.生态修复河流城区段微生物丰度和多样性较高,致病风险大;城郊段碳氮硫功能菌群丰度高,是物质循环的主要场所.

为了提高厂网一体化系统有机物的利用效率,构建"降解-沉积-冲刷"管网COD变化模型,考察了管网与污水厂对COD去除的贡献规律.结果表明在不受降雨影响时,管内COD呈整体下降趋势,管网对COD去除贡献率为15.91％,且ΔCOD与HRT呈正相关(相关系数0.865).污水厂进水COD浓度越低,其去除单位COD耗电量越高(相关系数-0.862).从合理利用COD强化污水厂脱氮除磷角度出发,建设分散式污水处理厂、选择分流制排水体制是缩短管内污水停留时间、提高污水厂进水碳源的有效方式.