分子技术在湿地微生物群落解析中的应用

人工湿地的研究和应用近年来受到了广泛重视。微生物是人工湿地系统的重要组成部分,其群落结构对于湿地的净化功能的发挥具有重要影响。与传统的微生物分析技术相比,分子生物学技术在解析人工湿地微生物群落结构时无需纯培养,具有高效、快速、简便的特点,使其广泛应用于环境微生物的研究。文章综述了近年来在聚合酶链反应技术（Polymerase Chain Reaction,PCR）基础上发展起来的几种新的分子生物技术,包括PCR-DGGE、LH-PCR、T-RFLP、PCR-SSCP和ARDRA,以及其在人工湿地微生物研究中的应用现状。通过这些分子技术,可以分析湿地处理特定废水过程中微生物的数量、丰度、多样性及优势种;鉴定湿地中特定功能菌群（如氨氧化细菌、反硝化细菌、除硫菌等）的数量、活动分布、空间变更及与污染物去除的关系;判断各种系统条件（如不同基质、植物、水力负荷等）的设置对微生物多样性和稳定性的影响。最后,对分子技术在湿地领域的未来发展进行了展望。     

Microalgae Scenedesmus obliquus as renewable biomass feedstock for electricity generation in microbial fuel cells （MFCs）

Renewable algae biomass, Scenedesmus obliquus, was used as substrate for generating electricity in two chamber microbial fuel cells （MFCs）. From polarization test, maximum power density with pretreated algal biomass was 102mW·m^2 （951mW·m^3） at current generation of 276mA·m^-2. The individual electrode potential as a function of current generation suggested that anodic oxidation process of algae substrate had limitation for high current generation in MFC. Total chemical oxygen demand （TCOD） reduction of 74% was obtained when initial TCOD concentration was 534mg · L^-1 for 150 h of operation. The main organic compounds of algae oriented biomass were lactate and acetate, which were mainly used for electricity generation. Other byproducts such as propionate and butyrate were formed at a negligible amount. Electrochemical Impedance Spectroscopy （EIS） analysis pinpointed the charge transfer resistance （112Ω ） of anode electrode, and the exchange current density of anode electrode was 1214 nA·cm^-2.     

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

A stormwater wetland treating non-point source pollution (NPS) from a 64 ha agricultural watershed was monitored over a period of five months. The results indicated that pH and dissolved oxygen (DO) were increased in the wetland due to the algal growth. The highest total suspended solids (TSS) concentration was observed in the aeration pond due to the resuspension of solids, decreased in the wetland. The respective decreases in total nitrogen (TN) and total kjeldahl nitrogen (TKN) were 15.9% and 28.7% on passing through the wetland. The nitrate and ammonia were increased by 45.4% and decreased by 79.9%, respectively. These variations provided strong evidence for the existence of nitrification. The total phosphorus (TP) and phosphate had respective reductions of 52.3% and 58.2% over the wetland. The total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) were also decreased. Generally, the TN, TP and phosphate removal efficiencies were positive. These positive removal efficiencies were mainly due to microbial activities, uptake by plants, and chemical precipitation at high pH. Negative removal efficiencies can be caused by continuous rainfall activities, with short antecedent dry days (ADDs) and unstable hydraulic conditions, some other biogeochemical transformations and algal growth also being important parameters.     

Up to 399 mV bioelectricity generated by a rice paddy-planted microbial fuel cell assisted with a blue-green algal cathode

Environmental Chemistry Letters - Microbial fuel cells are used as an alternative source of energy and for microbial degradation of waste and pollutants. Different types of microbial fuel cells...     

Shipboard bilge water treatment by electrocoagulation powered by microbial fuel cells

Reveals the synergy between microbial fuel cells and electrocoagulation. Demonstrates MFC-ECC shipboard wastewater treatment is advantageous. MFC-ECC integration enables energy neutral bilge water treatment. Ships generate large amounts of wastewater including oily bilge water, blackwater and greywater. Traditionally they are treated separately with high energy consumption. In this study we demonstrate the feasibility that these waste streams can be treated using an integrated electrocoagulation cell (ECC) and microbial fuel cell (MFC) process, which not only synergized the contaminants removal but also accomplished energy neutrality by directly powering EC with MFC electricity. Results showed that MFC stack powered ECC removed 93% of oily organics, which is comparable to the performance of an external DC voltage powered ECC. In the meantime, more than 80% of COD was removed from MFCs when fed with either acetate or municipal wastewater. Moreover, the ECC electrode area and distance showed notable effects on current generation and contaminants removal, and further studies should focus on operation optimization to enhance treatment efficiency.     

不同生态区土壤溶磷微生物的分布特征及影响因子

研究了盐渍区、重金属污染区和磷矿区土壤中溶磷微生物的数量、组成及与部分土壤化学因子的关系。结果表明,溶磷微生物在不同生态区土壤中的分布各不相同,磷矿区土壤中溶磷微生物数量和种群丰度普遍高于重金属污染区和盐渍区,但优势种属间数量差异不明显。重金属污染土壤中溶磷细菌比例较高,但种群单一,主要以巨大芽孢杆菌(Bacillus megaterium)为优势种,重金属污染区溶磷细菌比例与土壤重金属综合污染指数呈显著正相关(P<0.01),溶磷细菌丰度与有机质含量呈显著正相关(P<0.05)。盐渍土中溶磷细菌比例小,优势种群为巨大芽孢杆菌、假单胞杆菌属(Pseudomonassp.)和黄单胞杆菌属(Flavobacteriumsp.),其数量和种群丰度分别与有机质和有效磷含量呈显著相关关系(P<0.05)。     

Effect of wetland plant fermentation broth on nitrogen removal and bioenergy generation in constructed wetland-microbial fuel cells

● Fermentation broth facilitates N removal and energy yields in tertiary CW-MFC. ● Carbon sources are preferred for nitrogen removal over electricity generation. ● A mutual promotion relationship exists between acetic and humic acid in N removal. ● Humic acid boosts the abundances of functional genes relate to nitrogen metabolism. Constructed wetlands (CWs) are widely used as a tertiary treatment technology, and the addition of carbon sources can significantly improve advanced nitrogen removal. However, excessive carbon sources would lead to an increase in the effluent chemical oxygen demand in CWs, and microbial fuel cells (MFCs) can convert these into electricity. In this study, constructed wetland-microbial fuel cells (CW-MFCs) were built to achieve simultaneous nitrogen removal and electricity generation, using wetland plant litter fermentation broths as carbon sources. The total nitrogen removal in the groups with fermentation broth addition (FGs) reached 83.33%, which was 19.64% higher than that in the CG (group without fermentation broth), and the mean voltages in the FGs were at least 2.6 times higher than that of the CG. Furthermore, two main components of the fermentation broths, acetic acid (Ac) and humic acid (HA), were identified using a three-dimensional excitation emission matrix and gas chromatograph and added to CW-MFCs to explore the influence mechanism on the treatment performance. Denitrification and electrogenesis presented the same tendency: Ac&HA > Ac > CG’ (groups without Ac and HA). These results indicate that Ac and HA increased the abundance of functional genes associated with nitrogen metabolism and electron transfer. This study demonstrated that CW-MFC fermentation broth addition can be a potential strategy for the disposal of secondary effluent and bioelectricity generation.     

景观人工湿地微生物群落结构的季节变化

采用PCR-DGGE技术对梦清园人工芦苇湿地不同季节的细菌群落变化进行了研究。结果表明,随着水体流动和季节更替,人工湿地中优势细菌一直在变化。测序结果显示芽孢杆菌在系统中较占优势,4个季节里都可以检测出来。恶臭假单胞菌在春夏秋3季比较有优势,而冬天枯草芽孢杆菌比较适合在该芦苇湿地中生存。经湿地处理后,水体细菌群落的多样性下降,相似性升高,部分细菌被淘汰出水体,但适应的细菌生长较快,整体细菌数量上升。对底泥的研究中,随运行时间的增加,进水口与出水口的细菌相似性分别下降,且进水口的相似性下降要明显快于出水口。     

Improved electricity production and nitrogen enrichment during the treatment of black water using manganese ore-modified anodes

Environmental Chemistry Letters - The decline of fossil fuel availability is calling for alternative energy such as electricity produced by degradation of waste in microbial fuel cells. The...     

好氧反硝化菌种DF2的分离鉴定及生理生化特性分析

分离了新型的高效反硝化细菌并研究其生物脱氮效率。通过观察形态学、生理生化鉴定和16SrRNA基因同源分析来鉴定菌种,致力于研究微生物污水脱氮处理的实际效果和克服反硝化过程中有害中间产物的积累。利用BTB培养基从水平潜流人工湿地基质中初步筛选出了9株平板阳性菌,革兰阴阳性均有。经试验研究发现该9种菌株在好氧条件下均具有一定的脱氮能力,其中以DF2和DF3 2种菌株脱氮能力最为显著,在3 d时间内NOX--N去除率达到了95%以上,NO2--N仅有微量积累;而其它7种菌株对NO3--N的去除率可以达到98%以上,但是NO2--N积累比较严重,积累量达到了NO3--N去除的50%~70%左右。经测序分析鉴定DF2和DF3分别属于德克斯氏菌属(Derxia)和假单胞菌属(Pseudomonadaceae)。德克斯氏菌属作为除氮的反硝化菌属在以往的研究中鲜有报道,该菌在好氧条件下可以合成周质NAR的亚基基因(napA)。     

湿地生态系统碳汇与碳源过程的控制因子和临界条件

湿地生态系统由于其自身的结构组分特征,已成为地球表层系统中最为重要的碳汇。但是近年来对于湿地系统的不合理开发利用、降水减少等原因使其碳＂汇＂功能减弱,湿地的碳蓄积能力下降且有转变为碳＂源＂的趋势。文章从湿地生态系统的水份、植物类型、土壤厚度、微生物（底物、pH、温度、氧化还原条件）等方面总结了影响湿地碳汇/源过程的控制因子和临界交替条件。湿地水位的高低决定湿地的氧气环境,与甲烷产生量成正相关,但却与二氧化碳产生量有一定的负相关关系。湿地植物通过通气组织与根系分泌物等影响湿地碳的吸收与排放通量,湿地植株的高度、覆盖率等也是影响湿地作为碳汇与碳源的重要因素。不同深度土层由于其产甲烷菌、甲烷氧化菌等微生物活性不同导致各个土层碳吸收、排放通量的差异,通常浅层土壤中的CO2、CH4的产生率高于深层土壤。微生物的活跃程度直接影响到湿地碳的吸收与排放,影响活跃程度的因素包括湿地底物、pH、温度与氧化还原条件等。湿地底物浓度的增加会在一定程度上提高甲烷的产生率,中性或者是弱碱性环境是产甲烷菌的最适宜条件,在一定范围内温度越高,甲烷产生量越大,而温度对于二氧化碳的影响则是通过改变光合作用来实现。氧化还原电位与甲烷产生量成负相关关系,-150 mV是产甲烷菌产生甲烷的最高电位。总体上,由于湿地生态系统的复杂性和碳吸收与排放过程的复杂,以上这些因子相互作用,且在一定条件下会相互转化。最后针对如何充分发挥湿地生态系统的碳＂汇＂功能,控制湿地向碳＂源＂转化的条件措施方面进行了讨论,包括间歇灌溉、种植多年生草本植物或木本植物等来增强湿地的固碳能力。     

崇明岛新围垦区不同土地利用条件下的土壤呼吸研究

土地利用方式是影响温室气体减排的关键因子之一。新围垦土地因其土壤本底均一、土地利用历史简单短暂,使得评价短期土地利用对温室气体排放的影响成为可能。为此,在崇明东滩湿地新围垦区选取了本底均匀、利用历史简单的几种土地利用类型（旱田、水旱轮作农田、人工林带）,研究其土壤呼吸的变化及其与土壤环境间的关系,以期评价其各自的固碳和温室气体减排潜力。研究表明,2009年整个春季,土壤呼吸速率强度的顺序为水旱轮作[（0.30±0.08）mol.m-2.d-1]〉旱田[（0.18±0.04）mol.m-2.d-1]〉林带[（0.09±0.01）mol.m-2.d-1];春季各月份,水旱轮作田土壤呼吸速率变化波动较大,旱田较平稳,4、5月份最先达到日最高值,人工林带最为平稳,且始终具有较低的呼吸强度;旱田土壤呼吸速率均不能简单用土壤5 cm处温度及湿度进行解释,林带与水旱轮作田土壤呼吸速率与土壤5 cm处温度显著相关（P〈0.05）;整个春季,林带土壤呼吸与5 cm处温度及湿度均显著相关,其中与温度极显著相关（P=0.01）,水旱轮作田与旱田的土壤呼吸速率与两者均不相关。     

Sediment microbial fuel cell with floating biocathode for organic removal and energy recovery

A sediment microbial fuel cell (SMFC) with three dimensional floating biocathode (FBC) was developed for the electricity generation and biodegradation of sediment organic matter in order to avoid negative effect of dissolved oxygen (DO) depletion in aqueous environments on cathode performance and search cost-effective cathode materials. The biocathode was made from graphite granules with microbial attachment to replace platinum (Pt)-coated carbon paper cathode in a laboratory-scale SMFC (3 L in volume) filled with river sediment (organic content 49±4 g·kg^-1 dry weight). After start-up of 10 days, the maximum power density of 1.00W·m^-3 (based on anode volume) was achieved. The biocathode was better than carbon paper cathode catalyzed by Pt. The attached biofilm on cathode enhanced power generation significantly. The FBC enhanced SMFC performance further in the presence aeration. The SMFC was continuously operated for an over 120-day period. Power generation peaked within 24 days, declined gradually and stabilized at a level of 1/6 peak power output. At the end, the sediment organic matter content near the anode was removed by 29% and the total electricity generated was equal to 0.251 g of chemical oxygen demand (COD) removed.     

Recent advances in three typical configurations and applications of bioelectrochemical systems北大核心CSCD

As the world's freshwater resources and available energy are alarmingly decreasing, the bioelectrochemical system (BES) is a cutting-edge technology for the resolution of the resource and energy issue. Researchers have paid much attention to t he application of t he BES configuration. Based on t he brief i ntroduction of m icrobial f uel cell a nd m icrobial electrolytic cell structure, principles, and domestic and foreign research, the BES and its influencing factors are introduced, specifically including: microbial activity, electrode materials, and configuration. Three important aspects (i.e., the electrode chamber, the reaction chamber, and micro-sensor) are summarized, and the advantages and disadvantages of single-electrode and multi-electrode chambers are compared, based on the microbial desalination cell. Microbial electrolysis desalination cell: Microbial electrolysis desalination and chemical-production cell have been discussed to introduce increasing reaction chamber configuration; this review focuses on the research of BES monitoring with regards to biochemical oxygen demand. The potential applications of the research progress are explored. The results show that the configuration of multi-chamber microbial fuel cell is complex and its efficiency is low, while the single chamber configuration is advantageous. The reaction chamber added is mainly aimed at desalination, and the study of the desalination pool still needs to be focused on optimizing the cation exchange membrane to maintain the anode pH balance and reduce the air cathode dissolved oxygen. Microbial electrode sensor can be applied in more areas, and its sensitivity and long-term stability need to be further improved. However, there is relatively less research on the abundance and activity of electricigen communities; the configurations and scopes of application of BES are still the research priority. © 2018 Science Press. All rights reserved.     

Aquatic herbivores facilitate the emission of methane from wetlands

Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate methane emission from wetlands. Diffusive methane emission was monitored inside and outside bird exclosures, using static flux chambers placed over whole vegetation and over single shoots. Both methods showed significantly higher methane release from grazed vegetation. Surface-based diffusive methane emission from grazed plots was up to five times higher compared to exclosures. The absence of an effect on methane-cycling microbial processes indicated that this modulating effect acts on the gas transport by the plants. Modulation of methane emission by animal-plant-microbe interactions deserves further attention considering the increasing bird populations and changes in wetland vegetation as a consequence of changing land use and climate change.     

几种植物在生长过程中对人工湿地污水处理效果的影响

不同的植物及植物的不同生长阶段对人工湿地系统污水处理效果都有影响。对几种华南地区常见的湿地植物在其不同生长阶段处理污水的效果进行了研究,采用了不种植物的沙滤系统作对照。结果表明:(1)植物生长过程中,植物高度能反映污水处理效果总体上的变化;(2)在植物的生长过程中,各人工湿地系统污水处理能力总体上持续增强,各水质指标pH、DO、TN、NH3-N、NO3-N、TP和CODCr等均呈下降趋势,其中TP和CODCr呈逐步下降,pH、DO、TN、NH3-N、NO3-N则呈现锯齿形波动,但总体上仍是下降过程;(3)植物系统氮处理能力好于无植物沙滤系统,而对磷TP和CODCr的去除则恰好相反;(4)不同植物对人工湿地污水的处理效果影响不明显。研究结果对探讨人工湿地污水处理规律和植物在人工湿地中的作用提供了新的科学依据,并为指导人工湿地工程的运行提供了参考。     

Impact of hydraulic loading on removal of polycyclic aromatic hydrocarbons (PAHs) from vertical-flow wetland

The effects of polycyclic aromatic hydrocarbons (PAHs) removal on lab-simulated vertical wetland systems, each containing eight dominant species, under continuous- and intermittent-flow feeding modes, were determined. The main results were: (1) PAHs removal effect was greater in intermittent-flow system than in continuous-flow system, with the exception of the floating plant Hydrilla verticillata wetland. This may be due to pollutants remaining stable for longer duration under intermittent-flow mode, which is conducive to microbial, plant, and water absorption of PAHs, as well as to microbial decomposition and absorption by plant roots; (2) absorption and degradation rates of PAHs varied among wetland body plants in different periods with removal efficiencies of 30%–70% observed following the first and fifth cycles, and under high-performance degradation conditions; (3) mean removal rates of PAHs by hydrophytes under continuous-flow mode were as follows: H. verticillata (34.4%), Arundo donax (Gramineae) (33.2%), Phragmites australis (28.7%), Ipomoea aquatica Forsk (Convolvulaceae) (28.5%), Zizania aquatic (27.6%), Calla palustris (Araceae) (27.2%), Acorus calamus (26.8%), and Hardy canna (17.9%); (4) average rates of PAHs removal by hydrophyte under intermittent-flow mode were as follows: A. donax (40.5%), Z. aquatic (37.9%), A. calamus (37.0%), P. australis (36.9%), Hardy canna (34.6%), C. palustris (33.9%), I. aquatica (31.2%), and H. verticillata (29.3%).     

One-step ball milling-prepared nano Fe2O3 and nitrogen-doped graphene with high oxygen reduction activity and its application in microbial fuel cells

• Nano Fe₂O₃ and N-doped graphene was prepared via a one-step ball milling method. • The maximum power density of Fe-N-G in MFC was 390% of that of pristine graphite. • Active sites like nano Fe₂O₃, pyridinic N and Fe-N groups were formed in Fe-N-G. • The improvement of Fe-N-G was due to full exposure of active sites on graphene. Developing high activity, low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel cells. The full exposure of active sites in catalysts can enhance catalytic activity dramatically. Here, novel Fe-N-doped graphene is successfully synthesized via a one-step in situ ball milling method. Pristine graphite, ball milling graphene, N-doped graphene and Fe-N-doped graphene are applied in air cathodes, and enhanced performance is observed in microbial fuel cells with graphene-based catalysts. Particularly, Fe-N-doped graphene achieves the highest oxygen reduction reaction activity, with a maximum power density of 1380±20 mW/m² in microbial fuel cells and a current density of 23.8 A/m² at –0.16 V in electrochemical tests, which are comparable to commercial Pt and 390% and 640% of those of pristine graphite. An investigation of the material characteristics reveals that the superior performance of Fe-N-doped graphene results from the full exposure of Fe₂O₃ nanoparticles, pyrrolic N, pyridinic N and excellent Fe-N-G active sites on the graphene matrix. This work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.     

Effects of salinity on soil bacterial and archaeal community in estuarine wetlands and its implications for carbon sequestration: verification in the Yellow River Delta

Soils from two typical tidal salt marshes with varied salinity in the Yellow River Delta wetland were analysed to determine possible effects of salinity on soil carbon sequestration through changes in soil microbiology. The mean soil respiration (SR) of the salt water–fresh water mixing zone (MZ) was 2.89 times higher than that of the coastal zone (CZ) (4.73 and 1.63?μmol?m^?2?s^?1, respectively, p?Pseudomonas sp. and Limnobacter sp. that might have led to its higher dehydrogenase activity and respiratory rates. Additionally, the CZ possessed more Halobacteria and Thaumarchaeota with the ability to fix CO₂ than the MZ. Significantly lower soil salinity in MZ (4.25?g?kg^?1) was suitable for β-Proteobacteria, but detrimental for Halobacteria compared with CZ (7.09?g?kg^?1, p?相似文献   

Wetland Loss and Biodiversity Conservation

Abstract: Most species of wetland-dependent organisms live in multiple local populations sustained through occasional migration. Retention of minimum wetland densities in human-dominated landscapes is fundamental to conserving these organisms. An analysis of wetland mosaics was performed for two regions of the northeastern United States to assess the degree to which historical wetland loss alters the metrics of wetland mosaics and to assess potential future effects mediated by differently structured wetland regulations. These analyses indicated that profound reductions in wetland density and proximity are associated with increased human populations and that protections for all wetlands > 1 acre (0.4 ha) are likely required to retain wetland densities minimally sufficient to sustain the wetland biota.