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构筑根孔湿地氧化还原状况及其与水质净化的关系

文献类型：学位论文

作者王宝玲
学位类别硕士
答辩日期2014-11
授予单位中国科学院研究生院
授予地点北京
导师王为东
关键词构筑根孔湿地 氧化还原状况 根孔净化区 Biolog 生态板 磷脂脂肪酸 温室气体排放,constructed root-channel wetland (CRCW) redox condition root-channel purification zone Biolog ECO Plate phospholipid fatty acid (PLFA) greenhouse gas emission
其他题名Redox conditions and its relationship with water purification in constructed root-channel wetlands
学位专业环境科学
中文摘要      浙江省嘉兴市地处长江三角洲平原河网地区，其饮用水直接取自河流。但河网密集，污染源众多，水体呈有机微污染特征。构筑根孔湿地是仿照白洋淀自然湿地而构 建的饮用水源处理湿地，其景观格局布设借鉴了白洋淀天然芦苇型水陆交错带，核心技术是人工湿地生态根孔技术与多级塘/植物床-沟壕系统协同净化技术，以植 物床-沟壕系统为主要净化结构单元，其中各种塘系统和植物床-沟壕系统的复合串并联景观结构的异质性、人造生态根孔的微观结构异质性和优先导流效应以及合 理变化的水力调控手段使得湿地中存在着较多的物质持留和生物化学反应的“关键区域”。大规模生态根孔人工湿地在南方平原水网地区水源地保护和修复中的推广 和应用，迫切需要我们对该湿地系统中各功能区和结构单元的净化机理进行深入研究。
       本文将从氧化还原状况的角度，研究构筑根孔湿地水质净化与氧化还原状况变化存在的密切响应机制及耦合作用，研究构筑根孔湿地中特定氧化还原状况下的微生物 群落结构、浮游植物群落结构、微生物碳源利用情况、土壤酶分布、温室气体减排效应及对特征污染物如重金属、多环芳烃等的去除效果，深入探讨根孔湿地的水质 净化机理。通过本文的研究，深刻阐释构筑根孔湿地的根孔作用机制，为构筑根孔湿地的优化运行提供新的理论指导，为身处源水微污染地区的发展中国家解决城乡 饮用水安全问题提供了示范经验。
       本文主要结论如下：
      （1）湿地中氧化还原环境与土壤酶的分布：不同的氧化还原形态特征在构筑根孔湿地中已经初步形成，人造根孔周围土壤为氧化还原贫化区，呈还原状态，而自然 根孔周围土壤氧化还原形态特征为氧化还原新生体，呈局部氧化状态。长水塘中试湿地不同功能区中，随着水力流程的进行，水体中的溶解氧增加，湿地介质的氧化 性不断增加。石臼漾湿地沉积物中二价铁含量远高于三价铁含量，表明湿地总体上为还原状况，而氧化还原状态随着水力流程发生了剧烈的变化。 Fe(II)/Fe(III)的变化趋势表明湿地经历了还原性增加，后氧化性增加的趋势。贯泾港湿地前段二价铁含量和Fe(II)/Fe(III)较高， 源水沉积物还原性极强。根孔净化区植物床土壤中的还原性物质二价铁与铁离子对含量发生剧烈的波动，根孔净化区是氧化还原的剧烈交替区域。石臼漾湿地沉积物 中过氧化氢酶、脱氢酶、多酚氧化酶和过氧化物酶等多种氧化还原酶活性受湿地的污染负荷和氧化还原状况影响，在根孔净化区呈现剧烈的波动。常规土壤酶脲酶、 β-葡糖苷酶、磷酸酶等相关分析表明酶活性受底物水平和氧化还原状况因素影响较多。湿地中段的根孔净化区是氧化还原的剧烈交替区域，运行多年的石臼漾湿地 中氧化还原状况变化比运行初期的贯泾港湿地更加剧烈。
       （2）湿地中微生物群落结构特征分析：以Biolog ECO板和磷脂脂肪酸（PLFA）技术为基础，分析石臼漾构筑根孔湿地岸边带表层沉积物和植物根际土壤中的微生物群落结构特征。湿地入口有极高的生物量， 随着水力流程的变化，湿地内部生物量逐渐增加。湿地以磷脂脂肪酸表征的微生物生物量在表层沉积物中(7.19 nmol/g)高于岸边带土壤(6.47 nmol/g)，高于植物床-沟壕土壤(5.81 nmol/g)。湿地不同功能区具有不同的群落结构特征和代谢功能，核心根孔区的末端植物床土壤中微生物活动最剧烈，平均颜色变化率（AWCD）值和多样 性指数最大，其次是湿地岸边带前段预处理区沉积物及芦苇植物床-沟壕系统核心区土壤，反应相对最小的为湿地的后段表层沉积物和湿地中少数存在的香蒲植物床 根际土壤。石臼漾湿地六种碳源的利用效率依次为糖类>氨基酸类>聚合物类>双亲化合物类>羧酸 类>胺/氨基化合物类。湿地内反映氧化还原状况的微生物群落结构产生空间差异性，氧化还原状况剧烈交叠的根孔区微生物反应最为剧烈，磷脂脂 肪酸、碳源利用等手段可有效表征构筑根孔湿地氧化还原状况的空间分布格局。
      （3）湿地对典型污染物重金属、多环芳烃的累积作用：在嘉兴地区广泛性开展水体环境中的重金属普查，重金属元素的溶解总量大小依次为Sr > Zn > Ni > Li > Mn > Ti > Cu > Sb > Cr > V > As > Co > Sn > Hg > Pb > Cd > Tl，大多分布在水体中的颗粒物。长水塘中试构筑根孔湿地中，金属元素在中试湿地内部多累积在预处理区和根孔净化区，湿地对源水中的Cu、Ni、Zn和 Pb有很高的去除率。湿地重金属沉积的量占到总量的63.30%，植物床土壤累积量占到36.67%。植物吸收量仅不到0.1%。湿地自运行起经过494 天，总共可累积约86.18 kg的重金属。预处理塘为多环芳烃主要的沉积区，根孔生态净化区发挥重要的截留作用。随着水力流程，低分子量/高分子量（LMW/HMW）比值显著增加。 植物床-沟壕系统中，多环芳烃总量呈现高位沟>低位沟>植物床的分布，LMW/HMW比值在植物床土壤中明显高于高、低位小 沟中的比值。塘系统沉积物对多环芳烃持留量占38.63%，高于植物床土壤累积（34.52%），高于沟壕沉积物（26.86%）。因此构筑根孔湿地富集 可富集典型污染物重金属和多环芳烃，大大增加水体中的去除效率、降低其生态风险，而还原性较强的湿地前段预处理区和氧化还原状况剧烈交叠的根孔净化区是作 用的关键区域。
       （4）湿地夏季浮游植物群落结构分析与水质净化效果：运行初期的贯泾港湿地共鉴定出浮游植物5门70种，运行五年的石臼漾湿地共鉴定浮游植物6门68种。 贯泾港湿地浮游植物群落结构属于绿藻-蓝藻型，细胞数量均值为9374.69×104 cells/L；石臼漾湿地浮游植物群落属于绿藻-硅藻型，细胞数量整体低于贯泾港，均值为2526.36×104 cells/L。浮游植物群落多样性指数表明贯泾港和石臼漾湿地水体水质基本处于β-中污型到α-中污型，根孔净化区后水质显著好于湿地入口。浮游植物群 落指标受水体氧化还原电位、pH和各种营养盐指标影响较大，整体上石臼漾湿地水质优于贯泾港湿地。贯泾港构筑根孔湿地的水质净化效果较好，经过根孔净化区 和深度净化区处理后的水源水质相对较好。湿地对营养物质、各种叶绿素、藻类密度和重金属元素具有很高的去除效率，且受到湿地氧化还原状况的影响，主要发生 在根孔净化区。
      （5）湿地温室气体排放效应及影响因素：构筑根孔小试湿地中，甲烷整体上为吸收特征，二氧化碳和氧化亚氮为排放特征。二氧化碳在不同日期、不同季节的通量 变化幅度最大。二氧化碳的排放通量随着水力流程不断增加，氧化亚氮与甲烷在中段水力流程上有最大通量。大气温度显著影响了二氧化碳和氧化亚氮的排放特征。 甲烷的吸收通量在4%粗秸秆和4%细秸秆高于对照组，且粗秸秆的吸收通量更大，与随着混合秸秆比例成正比。二氧化碳排放通量排序为4%细秸秆 组< 空白对照组< 4%粗秸秆组，2%混合组< 对照组< 4%混合组< 3%混合组。氧化亚氮的排放通量排序为4%细秸秆< 4%粗秸秆< 空白对照组，2%混合组< 4%混合组< 3%混合组< 空白对照组。构筑根孔湿地对三种温室气体呈现出不同程度的减排效应，且与埋植秸秆粗细、混合比例有关。微生物生物量碳、微生物生物量氮、微生物生物量磷、 脲酶、β-葡糖苷酶、磷酸酶、磷脂脂肪酸、生态板碳源利用等手段表征了微生物对温室气体通量的影响。
英文摘要      Jiaxing is located within the stream network of the middle Yangtze River delta, Zhejiang Province and takes drinking water directly from rivers. But the river water was micro-polluted for complex stream network and various pollution sources. Constructed root-channel wetland (CRCW) was intended to purify and restore the healthy drinking source water. It is an innovative wetland configuration that includes the macroscopic plant-bed/ditch landscapes and mesoscopic root-channel structures originated from Baiyangdian Lake in North China. This wetland was based on constructed root-channel patented technologies, and the core technology focused on the combination of multilevel ponds and plant-bed/ditch systems and referred the plant-bed/ ditch system as the major purification structural units. The heterogeneity of various functioning zones such as macroscopic plant-bed/ditch landscapes and mesoscopic root-channel structures, the preferential flow effect and the reasonable hydraulic control measurement became the fundamentary reason that the wetland had many hotspots for removal and retention of pollutants and biochemical reactions. The wide development and application for constructed root-channel wetlands for protection and restoration of drinking water in southern stream network forced us to deep explore the mechanism of water purification.
      In this thesis, from the view of redox reactions, we studied the close internship between the redox conditions and water purification in constructed root-channel wetlands. The specific work involved in the distribution of reduction materials, the microbial community structure by PLFA and Biolog Eco plates, soil enzyme activities, the removal and retention of typical pollutants such as heavy metals and PAHs, the phytoplankton community structure and the emission of greenhouse gas to deep understand the mechanism of water purification. Our study deeply revealed the mechanism of root channels in CRCW, exhibited the new theories for the better operation of wetland and provided a meaningful example for other developing countries that may be facing similar problems relating to micro-pollution of their drinking water.
      The major findings are as follows:
      (1) The distribution of redox circumstance and soil enzyme in constructed root-channel wetlands: different redoximorphic features had developed that the soil close to artificial root channel was RMFs depletion with reduction condition and the soil close to natural root channel was RMFs concentration in relatively oxidability. In Changshuitang pilot wetland, dissolved oxygen increased along with hydraulic flow pathways, and that’s to say the oxidability was increased from the inlet to outlet in wetland. The Fe(II) was higher than Fe(III) in Shijiuyang wetland sediment and the wetland was whole in reduction condition. The redox conditions in surface sediments had spatial variation along with hydraulic flow pathways. Fe(II)/Fe(III) changed dramatically and the reducibility increased first and then the oxidability increased. The source water sediment had the highest Fe(II) and Fe(II)/Fe(III) in Guanjinggang wetland, showing high reduction condition in source sediment. Root-channel purification zones had much variation for Fe(II) and Fe(II)/Fe(III) and revealed dramatic redox conditions. Catalase, dehydrogenase, polyphenol oxidase and peroxidase had much variation in Shijiuyang wetland, especially in root-channel purification zones and the redox enzyme activities were influenced by pollution loads and redox conditions. The enzyme of phosphatase, β-glucosidase and urease were also influenced by substance level and redox conditions. The root-channel purification zones which were located in the middle part of wetland were the area for overlapped reduction and oxidability. The redox variation in Shijiuyang wetland (in operation for five years) was rather higher than that in Guanjinggang wetland (in operation for one year).
      (2) The microbial community structure:    Two technologies PLFA and Biolog Eco plates were  used to study  the microbial community  structure in Shijiuyang weltland.The inlet  had the rather  high biomass  and the biomass  indicated by  PLFA increased along with  hydraulic flow  pathways in  the inner  part  of wetland.  The average  total biomass   contents  marked   by   PLFAs  declined   as   the  following   order:  surface sediments  (7.19 nmol/g)  >  riparian plant-bed  soils  (6.47 nmol/g)  >  plant-bed/ditch system soils  (5.81 nmol/g). From  Biolog Eco plates,  different functioning zones  had various  microbial   communities  and   the  community-level   physiological  profiling (CLPP).  The end  part  of  reed plant-bed  soil  in  purification zones  had  the  highest average  well  color  development  (AWCD),  richness  indices,  evenness  indices  and diversity indices, indicating  the most active reaction  for microbes. Then the  first part sediment and  reed plant-bed soil  in core  purification zones had  relative high indices while  the latter  part  of  surface  sediment and  cattail  plant-bed  soil  had  the lowest activities.  The efficiency  of  sole-carbon-source in  Shijiuyang  wetland followed  the descending order: Carbohydrates>Amino acids>Polymers>Miscellaneous>Carboxylic acids>Amines/amides.  The  microbial  communities influenced  by  redox  conditions had spatial variation in surface sediment and plant-bed  soils in Shijiuyang constructed root-channel  wetland.   The  root-channel   purification  zones   had  the   most  active microbial activities for its overlapped reduction and oxidability. The PLFA and Biolog Eco plate  technologies were  effective  to symbolize  the spatial  distribution of  redox conditions in constructed root-channel wetlands.
    (3) The  distribution and  accumulation effect of  heavy metals  and PAHs:  In the wide  survey  of  heavy  metals   in  surface  stream  water  of  Jiaxing   area,  the  total dissolved concentration ordered as follows: Sr > Zn  > Ni > Li > Mn > Ti > Cu > Sb > Cr > V > As > Co > Sn  > Hg > Pb > Cd > Tl. Most heavy metals were  retained in the particle parts. In surface sediment, plant-bed subsurface soil, water,  and aquatic plants of Changshuitang pilot wetland,  monitoring results showed that pond/ditch sediments and   plant-bed  soil   retained   a  significant   amount   of   heavy  metals,   mainly   in pre-treatment and root-channel  purification zones. Water monitoring results  indicated that Cu, Ni, Zn, and  Pb had good removal rate. Rough estimation  revealed that heavy metal mass  in the  pond/ditch sediments  accounted for 63.30%  and that  in plant-bed soil  36.67%,  while  plant  uptake  occupied  only  0.03%.  The  1.83  ha  wetland  has retained about 86.18  kg total heavy  metals within 494 days  after operation. Contents of  sumPAHs in  pretreatment  zones were  higher  than  those in  other  zones  of pilot wetland. The ratio of low-molecular-weight  (2-3 rings) to high-molecular-weight (4-6 rings) PAHs  (LMW/HMW) increased  with the hydraulic  process in  five functioning zones. In four plant-bed/ditch systems, any mean LMW/HMW was the highest among the small  units  and the  mean LMW/HMW  ratio in  plant-bed  soils was  higher than LMW/HMW in  both  low ditches  and high  ditches.  Concentration of  total PAHs  in water   declined   obviously   after   root-channel  purification   zones.   Mass   balance estimation  revealed that  PAHs  mass in  the  pond  sediments accounted  for  38.63%, with  26.86%  in  ditch  sediments  and  34.52%   in  plant-bed  soil.  Constructed  root channel wetland  is  proved to  be effective  in  the retention  of typical  pollutants like heavy metals and PAHs and provide effective guarantee  for the safe usage of drinking water.  The  pretreatment  and  root-channel  purification  zones  with  complex   redox conditions were the key area.
    (4)  Phytoplankton  community   structure  and  water  purification  efficiency   of constructed root-channel wetlands: A total of 70 phytoplankton species belonging to 5 phyla  were  identified in  Guanjinggang  wetland  during  its initial  operation  period, while  Shijiuyang  wetland  had  68  phytoplankton  species  belonging  to  6  phyla  at five-year operation period. Guanjinggang  wetland had average phytoplankton density 9374.69×104 cells/L  and  the  phytoplankton  type was   Chlorophyta-Cyanophyta. While Shijiuyang   wetland    had   phytoplankton   density    2526.36×104   cells/L   and   the phytoplankton  type  was  Chlorophyta-Bacillariophyta.  Water  quality  of  both  wetlands ranged  from β-mesosaprobic  pattern  to α-mesosaprobic  pattern.  The phytoplankton community structure was influenced by Eh、pH and many nutrient indexes. Shijiuyang had  better  water   quality  than  Guanjinggang   wetland  on  the  whole.   Purification efficiency of Guanjinggang  wetland on polluted  water source was  rather high during its commissioning  period.  After root  channel zones  and deep  purification zone,  the wetland  had  improved  the water  quality  and  rather  good  removal  rates  on  major indexes such as nutrients, chlorophyll, algae density and heavy metals.
      (5) Emission of greenhouse gases in pilot  constructed root-channel wetland: CH4 was negatively  emitted.  CO2 and  NO2 were  positively emitted.  The sampling  dates and season had  the biggest effects  on the CO2  fluxes. Along with  the hydraulic flow pathways, the fluxes  of CO2 increased while the fluxes  of NO2 and CH4 had  both the
highest value  in the  middle part.  Temperature significantly  influenced the  fluxes of CO2 and NO2.  In different treatment of buried  stalks, the fluxes of CH4  were ordered as thick 4% >thin 4%  >control and increased with the percentage of  mixed treatment. The   fluxes   of   CO2   were   ordered   as   thin    4%
源URL[http://ir.rcees.ac.cn/handle/311016/34512]  
专题生态环境研究中心_环境水质学国家重点实验室
推荐引用方式
GB/T 7714		 王宝玲. 构筑根孔湿地氧化还原状况及其与水质净化的关系[D]. 北京. 中国科学院研究生院. 2014.

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来源：生态环境研究中心

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