酸性冲击对微生物电解产氢阳极菌群影响及功能基因变化解析

微生物电解产氢工艺是借助能够直接与电极传递电子的功能菌在阳极降解有机质并将产生的电子在阴极与质子结合回收氢气能源的新技术.采用市政废水在固定外加电压相同条件下直接启动15个反应器,以葡萄糖为碳源驯化获得电极功能菌群,稳定运行1个月获得反应器稳定产氢和伴随产甲烷效能.初始稳定时采用pH为7的磷酸盐缓冲液可以获得稳定的产气量,平行反应器表现出不同的氢气和甲烷产量.最高产氢反应器的氢气转化率为32.2%,氢气产率为(3.9±0.6)mol·mol-1(以每mol葡萄糖产生的H2量(mol)计,下同);相同条件下最低产氢效率反应器的甲烷转化率则可达到48.4%.通过48 h阳极生物膜的酸性冲击试验对阳极菌群功能恢复效果进行分析,发现消除冲击10~15 d反应器的电子传递效率得到恢复,但功能菌群多样性增加,氢气与甲烷比例发生变化.最高产氢反应器氢气产率降低1.8 mol·mol-1,而甲烷增量为0.4 mol·mol-1(以每mol葡萄糖产生的CH4量(mol)计,下同).通过关键功能基因分析发现,初始产氢效能高的反应器功能菌群中电子传递功能菌优势较大;阳极功能菌群受到短暂酸性冲击后,基于细胞色素C基因的相关菌群能够较快恢复,其电子传递能力恢复更快;与碳源降解和产甲烷相关基因群落受酸性冲击后变化较为显著,甲烷增量与氢气减少量基本符合反应计量关系.     

气体分离循环对高温厌氧消化过程的影响

采用厌氧序批式反应器,研究了气体循环(包括气体直接循环和脱除气体中的氢气后循环)对以葡萄糖和乙酸钠配制的模拟废水在高温厌氧消化过程中乙酸代谢速率、出水性质及微生物相的影响,并采用尺寸排除色谱和三维荧光光谱技术,对溶解性微生物产物(SMP)的分子量分布和荧光物质组成进行了分析.结果显示,气体循环使得出水中残余挥发性脂肪酸的浓度由238.2mg/L(未脱氢)和129.6mg/L(脱氢)分别减少至8.5mg/L和8.2mg/L,并最终降低了SMP产量,45d时分别降至气体循环前的36.8%和59.2%.脱氢气体循环促进了乙酸化和乙酸氧化,导致了微生态环境和甲烷化基质浓度的差异,促进了高分子量SMP向低分子量SMP的转化,污泥中的微生物形态亦发生了较大变化.可见气体循环改善了基质与微生物的混合状况,改善了出水水质,而脱氢气体循环加速了乙酸的代谢,有望更快速地解除易降解有机物高温厌氧消化过程中的酸抑制,提高厌氧消化效率.     

A comparative study on the alternating mesophilic and thermophilic two-stage anaerobic digestion of food waste

An alternating mesophilic and thermophilic two stage anaerobic digestion(AD) process was conducted. The temperature of the acidogenic(A) and methanogenic(M) reactors was controlled as follows: System 1(S1) mesophilic A-mesophilic M;(S2) mesophilic A-thermophilic M; and(S3)thermophilic A-mesophilic M. Initially, the AD reactor was acclimatized and inoculated with digester sludge. Food waste was added with the soluble chemical oxygen demand(SCOD) concentrations of41.4–47.0 g/L and volatile fatty acids of 2.0–3.2 g/L. Based on the results, the highest total chemical oxygen demand removal(86.6%) was recorded in S2 while S3 exhibited the highest SCOD removal(96.6%). Comparing S1 with S2, total solids removal increased by 0.5%; S3 on the other hand decreased by 0.1 % as compared to S1. However, volatile solids(VS) removal in S1, S2, and S3was 78.5%, 81.7%, and 79.2%, respectively. S2 also exhibited the highest CH4 content, yield, and production rate of 70.7%, 0.44 L CH4/g VSadded, and 1.23 L CH4/(L·day), respectively. Bacterial community structure revealed that the richness, diversity, evenness, and dominance of S2 were high except for the archaeal community. The terminal restriction fragments dendrogram also revealed that the microbial community of the acidogenic and methanogenic reactors in S2 was distinct. Therefore,S2 was the best among the systems for the operation of two-stage AD of food waste in terms of CH4production, nutrient removal, and microbial community structure.     

腐殖酸和产甲烷抑制剂对厌氧污泥发酵产氢效能的影响

为提高厌氧污泥的发酵产氢能力,采用间歇培养方式考察了不同产甲烷抑制剂与腐殖酸联合作用对厌氧污泥发酵葡萄糖产氢效能的影响,并通过Illumina MiSeq测序揭示了微生物群落结构的变化规律.结果表明,在葡萄糖初始浓度为500 mg·L^-1条件下,经过120 h的连续培养后,对照的累计产氢量为1.2 mL,存在明显的耗氢现象.当加入0.02%氯仿（V/V）、0.04%氯仿（V/V）或2-溴乙酸磺酸钠（10 mmol·L^-1）后,耗氢现象得到有效控制,它们的累计产氢量分别为15.7、13.2和9.4 mL.当向发酵系统同时加入产甲烷抑制剂和腐殖酸后,可以显著提高厌氧污泥的产氢效能.其中,0.02%氯仿和腐殖酸联合作用的促进效果最佳,其累计产氢量和最大产氢速率（R_max）分别达到了17.4 mL和0.24 mL·L^-1.相反,当替硝唑作为产甲烷抑制剂时,仍然存在耗氢现象.Illumina MiSeq测序结果表明,发酵系统中优势菌群的相对丰度存在显著差异.在对照系统中,Ottowia、Ignavibacterium、Nitrospira、Saccharibacteria_genera_incertae_sedis和Terrimona为优势菌群,其相对丰度为2.2%~4.2%.当0.02%氯仿和腐殖酸加入发酵系统后,Ottowia和Saccharibacteria_genera_incertae_sedis的相对丰度较对照分别增加了11.9%和31.8%,而Nitrospira的含量显著减少.     

Town-scale microbial sewer community and H2S emissions response to common chemical and biological dosing treatments

Controlling hydrogen sulfide (H₂S) odors and emissions using a single, effective treatment across a town-scale sewer network is a challenge faced by many water utilities. Implementation of a sewer diversion provided the opportunity to compare the effectiveness of magnesium hydroxide (Mg(OH)₂) and two biological dosing compounds (Bioproducts A and B), with different modes of action (MOA), in a field-test across a large sewer network. Mg(OH)₂ increases sewer pH allowing suppression of H₂S release into the sewer environment while Bioproduct A acts to disrupt microbial communication through quorum sensing (QS), reducing biofilm integrity. Bioproduct B reduces H₂S odors by scouring the sewer of fats, oils and grease (FOGs), which provide adhesion points for the microbial biofilm. Results revealed that only Mg(OH)₂ altered the microbial community structure and reduced H₂S emissions in a live sewer system, whilst Bioproducts A and B did not reduce H₂S emissions or have an observable effect on the composition of the microbial community at the dosed site. Study results recommend in situ testing of dosing treatments before implementation across an operational system.     

脱硫石膏对稻田CH4释放及其功能微生物种群的影响

为探究脱硫石膏对温室气体CH_4排放及其功能微生物种群的影响,采用静态暗箱/气相色谱法,高通量测序和荧光定量PCR技术,研究了FGDG0(0 t·hm~(-2))、FGDG1(2 t·hm~(-2))、FGDG2(4 t·hm~(-2))、FGDG3(8 t·hm~(-2))、FGDG4(16 t·hm~(-2))这5个施加脱硫石膏处理下CH_4排放特征、稻田细菌群落结构及产甲烷菌和甲烷氧化菌丰度的变化.结果表明施加脱硫石膏后,土壤p H显著提高(P0.05),土壤氧化还原电位、有机质、速效钾含量增加,但处理间无显著差异(P0.05);稻田CH_4平均排放通量随着脱硫石膏用量增加而降低,且FGDG1FGDG2FGDG3FGDG4,较对照分别减少31.56%、57.30%、83.60%、90.66%;与对照相比,FGDG1、FGDG2处理增加了土壤细菌丰富度和多样性,但用量超过4 t·hm~(-2)后,细菌丰富度和多样性逐渐降低;与对照相比,稻田土壤硫酸盐还原菌属相对丰度显著提高6.98%~13.56%,甲烷氧化菌pmo A基因丰度增加0.3%~6.2%,产甲烷菌mrc A基因丰度显著下降2.4%~15.8%,且丰度比(pmo A/mcr A)随着脱硫石膏用量增加而增大;相关性分析表明,CH_4平均排放通量与土壤中硫酸盐还原菌属相对丰度呈显著负相关,与产甲烷菌mcr A基因丰度呈显著正相关,与pmo A/mcr A比呈显著负相关.综上,脱硫石膏能够提高稻田土壤细菌群落多样性,抑制稻田CH_4排放.     

Hydrogen gas production in a microbial electrolysis cell by electrohydrogenesis

Electrohydrogenesis is a bio-electrochemical process where organic material is microbially oxidized to protons and electrons, which in turn are reduced to form hydrogen gas (H₂). The reactor in which these reactions occur is termed a microbial electrolysis cell (MEC). The microorganisms that colonize the anode are known as electricigens and behave as biological catalysts, significantly reducing the energy required to drive this process. Electricigens are capable of complete substrate degradation, leading to very high cathodic H₂ recovery efficiencies from sources previously considered organic waste. In this short review, the origination of the bio-electrochemical system (BES) is introduced, mechanisms for electron transfer between microbe and electrode are discussed, the challenges these electrochemical systems face are presented, and finally an overview of current MEC systems and their respective performance is evaluated. Electrohydrogenesis has established itself as a promising technology for sustainable H₂ production from renewable sources.     

Methanogene Bakterien

Methanogenic bacteria area diverse group of anaerobic procaryotes that ferment CO₂ plus H₂ to CH₄. Besides their unusual energy metabolism they are unique in that their cell walls do not contain murein, and in that their cell membranes are composed of isoprenoid lipids. Coenzymes occur which are not found in any other living organism. The translation apparatus differs, e.g., in not being affected by antibiotics known to be inhibitors of procaryotic protein synthesis. Most of the methanogens can grow on CO₂ as sole carbon source; autotrophic CO₂ fixation does not, however, proceed via reactions of the Calvin cycle. Molecular genealogical analysis has revealed that methanogenic bacteria constitute a grouping phylogenetically distinct from most other procaryotes.     

Microbial community structures in an integrated two-phase anaerobic bioreactor fed by fruit vegetable wastes and wheat straw

The microbial community structures in an integrated two-phase anaerobic reactor（ITPAR）were investigated by 16 S r DNA clone library technology. The 75 L reactor was designed with a 25 L rotating acidogenic unit at the top and a 50 L conventional upflow methanogenic unit at the bottom, with a recirculation connected to the two units. The reactor had been operated for 21 stages to co-digest fruit/vegetable wastes and wheat straw, which showed a very good biogas production and decomposition of cellulosic materials. The results showed that many kinds of cellulose and glycan decomposition bacteria related with Bacteroidales,Clostridiales and Syntrophobacterales were dominated in the reactor, with more bacteria community diversities in the acidogenic unit. The methanogens were mostly related with Methanosaeta, Methanosarcina, Methanoculleus, Methanospirillum and Methanobacterium; the predominating genus Methanosaeta, accounting for 40.5%, 54.2%, 73.6% and 78.7% in four samples from top to bottom, indicated a major methanogenesis pathway by acetoclastic methanogenesis in the methanogenic unit. The beta diversity indexes illustrated a more similar distribution of bacterial communities than that of methanogens between acidogenic unit and methanogenic unit. The differentiation of methanogenic community composition in two phases, as well as pH values and volatile fatty acid（VFA） concentrations confirmed the phase separation of the ITPAR. Overall, the results of this study demonstrated that the special designing of ITPAR maintained a sufficient number of methanogens, more diverse communities and stronger syntrophic associations among microorganisms, which made two phase anaerobic digestion of cellulosic materials more efficient.     

基于针铁矿强化乙酸产甲烷过程的ADM1模型修正与模拟研究

为探究针铁矿对乙酸产甲烷途径的调控作用,利用ADM1模型（厌氧消化1号模型）对添加针铁矿的产甲烷过程进行模拟研究.首先引入氧化还原介质作为新变量,模拟SAO（syntrophic acetate oxidation,互营乙酸氧化）过程中的种间电子转移,进而建立包含DIET（direct interspecies electron transfer,直接种间电子传递）产甲烷过程的ADM1修正模型,最后利用该模型对各产甲烷途径的贡献进行评价.结果表明:①c（乙酸）分别为12和20 mmol/L时,添加40~2 000 mg/L针铁矿明显提高了乙酸体系的产甲烷速率.②修正的ADM1模型能够有效地模拟针铁矿强化乙酸产甲烷过程.③12、20 mmol/L乙酸体系的敏感性参数km_Xst（最大比乙酸氧化速率）校准值分别从1.02、1.46升至1.76、2.03,km_DIET（最大比电子消耗速率）校准值分别从0.78、1.48升至2.44、3.99,表明添加针铁矿提高了互营体系的种间电子传递速率.修正的ADM1模型对各产甲烷途径贡献的计算结果显示,针铁矿对DIET过程的强化作用与其添加量呈正相关,添加2 000 mg/L针铁矿试验组[c（乙酸）为12 mmol/L]中DIET和SAO产甲烷的贡献率相比对照组分别提升了117.99%和130.73%.研究显示,修正的ADM1模型能够有效地模拟针铁矿对乙酸产甲烷过程的强化作用,并且能用于评价各产甲烷途径的贡献.      

水稻土中甲硫氨酸分解释放挥发性含硫气体的影响因素

为了探讨水稻土中含硫气体产生和释放的途径 ,在室内培养条件下 ,测定了南京水稻土中含硫气体的释放 .从该淹水土壤中测出 3种含硫气体 ;羰基硫 (COS)、二甲基硫 (DMS)和少量硫化氢 (H₂S)气体 .当土壤中加入甲硫氨酸后 ,DMS气体的释放量有了明显增加 ,此外还有大量甲硫醇 (CH₃SH)和二甲基二硫 (DMDS)气体测出 .而 COS在好氧条件 (普通大气淹水 )下的释放量明显增加 ,在厌氧条件 (充氮淹水 )下的释放量变化不明显 ;只有 H₂S的释放量几乎没变 .这些结果表明 ,甲硫氨酸的分解可能是 COS、DMS、CH₃SH和 DMDS的产生源之一 ,且释放含硫气体的种类明显不同于胱氨酸和半胱氨酸 .在好氧 (普通大气 )条件下 ,DMDS和 CH₃SH的释放量低于厌氧情况 (充氮气 )下的释放量 ,DMS则高于厌氧条件下的释放量 .这表明 ,水稻土中甲硫氨酸分解产生 DMDS和 CH3SH需较强的还原条件 ,产生这 2种气体的微生物需要严格的厌氧条件 .产生 DMS的微生物则比前者需要高一些的含氧量 .土壤 pH值和含水量及光照对甲硫氨酸分解释放含硫气体均有影响 .各含硫气体在持水率 50%、普通大气、光照条件下的释放量明显高于无光照条件下的释放量 .     

投加颗粒活性炭和二氧化锰对剩余污泥厌氧消化的影响

厌氧系统添加碳和金属纳米材料是强化厌氧消化的有效策略.为考察投加GAC和MnO₂对剩余污泥厌氧消化过程的影响,设置了空白组（R0）、GAC组（R1）、MnO₂组（R2）以及GAC/MnO₂组（R3）4组间歇实验,研究GAC和MnO₂的投加对剩余污泥厌氧消化效率、微生物活性和微生物群落结构的影响.结果表明,反应器运行28 d后,与R0相比,R1和R3的产CH₄速率分别提高了68.18%和51.35%,R2的产CH₄量降低了21.25%.GAC和MnO₂的单独或者混合投加,对厌氧发酵过程均有促进作用.Mn²⁺与剩余污泥释放的磷酸盐生成磷酸盐沉淀对厌氧代谢通道的阻塞作用,造成R2产CH₄效率变低.GAC优良导电性、吸附能力和MnO₂/Mn²⁺的催化作用是R3产CH₄效率增强的主要原因.正常代谢条件下,投加GAC、MnO₂和GAC/MnO₂均可以提高污泥厌氧消化系统微生物活性.微生物群落分析表明,GAC和MnO₂促进了产甲烷菌Methanobacterium和Methanosaeta的富集,强化了发酵细菌和产甲烷菌的种间电子传递,促进了剩余污泥厌氧发酵过程和CH₄的产生.     

SCAR处理城市生活污水的效能及其微生物群落动态分析

利用强化循环厌氧反应器(SCAR)处理模拟城市生活污水,研究不同负荷条件下的反应器运行特征、污泥特性及微生物种群结构.结果表明,水力停留时间(HRT)为6 h可以作为反应器高效运行的关键控制参数,该条件下污水化学需氧量(COD)去除率达到75%以上.随着反应器容积负荷的逐渐提高,颗粒污泥中辅酶F420和产甲烷活性(SMA)逐渐增加,胞外聚合物(EPS)含量也不断提高,其中紧密黏附EPS(TB-EPS)含量的增加尤其明显.厌氧颗粒污泥性状和反应器对污染物的去除效率同时受到污泥负荷和HRT的影响,微生物的群落结构及其在反应器中的空间分布也受到污泥负荷的影响,不同代谢特征微生物在反应器不同空间位置的相对丰度随着污泥负荷的调整而改变.     

Perturbations to tropospheric oxidants, 1985–2035: 2. Calculations of hydrogen peroxide in chemically coherent regions

Increasing global emissions of trace gases NO, CH₄, and CO, along with perturbations initiated by changes in stratospheric O₃ and H₂O, may cause tropospheric hydrogen peroxide (H₂O₂) levels to change. Specific scenarios of CH₄CONO emissions and global climate changes are used to predict HO₂ and H₂O₂ changes from 1985 to 2035 in a one-dimensional model that simulates different chemically coherent regions (e.g. urban, non-urban continental and marine mid-latitudes; marine and continental low latitudes).If CH₄ and CO emissions continue to increase throughout the troposphere at current rates (1% yr⁻), there will be large increases in H₂O₂, for example, more than 100% in the urban boundary layer from 1985 to 2035. Globally, H₂O₂ will increase 22% with HO₂ increasing 8% and O₃ increasing 13%. When CH₄, CO and NO emissions are specified on a regionally varying basis and are parameterized for high and low potential growth rates, globally averaged increases in surface concentrations are 12% for H₂O₂ and 18% for O₃. A global warming (with increased H₂O vapor) or stratospheric O₃ depletion superimposed on CH₄, CO and NO emissions changes will cut O₃ increases but add to peroxide, increasing levels as much as 150% above present day in some regions.Both globally uniform and region-specific scenarios predict a 10–15% loss in global OH from 1985 to 2035. Thus, conversion of OH to HO₂ and H₂O₂ in the atmosphere may signify a loss of gaseous oxidizing capacity in the atmosphere and an increase in aqueous-phase oxidizing capacity.     

化学预氧化对苏氨酸生成三氯乙醛的影响

以具有最大比三氯乙醛生成潜能(SCHFP)的苏氨酸为研究对象,分析了次氯酸钠(NaClO)、二氧化氯(ClO_2)、高锰酸钾(KMnO_4)、过氧化氢(H_2O_2)、臭氧(O_3)和臭氧过氧化氢(O_3/H_2O_2)等预氧化剂对三氯乙醛(CH)生成的影响,以确定合适的预氧化剂及其适宜投加量,为CH的控制提供指导.结果表明,能够有效去除一天CH生成量(CH1d)的预氧化方式依次为H_2O_2、ClO_2、KMnO_4和NaClO,适宜投加量分别为3、0.5、0.6和0.5mg·L-1,对CH1d相应的去除率分别为61.54%、47.63%、29.77%和10.94%;能够有效去除CH生成潜能(CHFP)的预氧化方式依次为KMnO_4、NaClO、H_2O_2和ClO_2,适宜投加量分别为0.6、0.5、3和0.5mg·L~(-1),对CHFP相应的去除率分别为41.01%、33.38%、8.36%和2.40%;O_3和O_3/H_2O_2预氧化能够使CH1d和CHFP增加,不适用于对CH的控制.     

Structure and function of rhizosphere and non-rhizosphere soil microbial community respond differently to elevated ozone in field-planted wheat

To assess the responses of the soil microbial community to chronic ozone(O_3), wheat seedlings(Triticum aestivum Linn.) were planted in the field and exposed to elevated O_3(e O_3)concentration. Three treatments were employed:(1) Control treatment(CK), AOT40 = 0;(2) O_3-1, AOT40 = 1.59 ppm·h;(3) O_3-2, AOT40 = 9.17 ppm·h. Soil samples were collected for the assessment of microbial biomass C, community-level physiological profiles(CLPPs), and phospholipid fatty acids(PLFAs). EO_3 concentration significantly reduced soil microbial carbon and changed microbial CLPPs in rhizosphere soil, but not in non-rhizosphere soil.The results of the PLFAs showed that e O_3 concentrations had significant effects on soil community structure in both rhizosphere and non-rhizosphere soils. The relative abundances of fungal and actinomycetous indicator PLFAs decreased in both rhizosphere and non-rhizosphere soils, while those of bacterial PLFAs increased. Thus the results proved that e O_3 concentration significantly changed the soil microbial community function and composition, which would influence the soil nutrient supply and carbon dynamics under O_3 exposure.     

The effects of climate warming on microbe-mediated mechanisms of sediment carbon emission

Due to significant differences in biotic and abiotic properties of soils compared to those of sediments, the predicted underlying microbe-mediated mechanisms of soil carbon emissions in response to warming may not be applicable for estimating similar emissions from inland water sediments. We addressed this issue by incubating different types of sediments, (including lake, small river, and pond sediments) collected from 36 sites across the Yangtze River basin, under short-term experimental warming to explore the effects of climate warming on sediment carbon emission and the underlying microbe-mediated mechanisms. Our results indicated that under climate warming CO₂ emissions were affected more than CH₄ emissions, and that pond sediments may yield a greater relative contribution of CO₂ to total carbon emissions than lake and river sediments. Warming-induced CO₂ and CH₄ increases involve different microbe-mediated mechanisms; Warming-induced sediment CO₂ emissions were predicted to be directly positively driven by microbial community network modularity, which was significantly negatively affected by the quality and quantity of organic carbon and warming-induced variations in dissolved oxygen, Conversely, warming-induced sediment CH₄ emissions were predicted to be directly positively driven by microbial community network complexity, which was significantly negatively affected by warming-induced variations in pH. Our findings suggest that biotic and abiotic drivers for sediment CO₂ and CH₄ emissions in response to climate warming should be considered separately when predicting sediment organic carbon decomposition dynamics resulting from climate change.     

基于mcrA基因的厌氧颗粒污泥产甲烷菌群分析

基于mcrA基因对阿维菌素废水处理工业化UASB厌氧颗粒污泥中产甲烷菌群进行分析,并与基于16S rRNA基因的产甲烷菌群分析结果进行比较.结果表明,基于2种目标基因PCR产物的DGGE图谱存在差异,但根据图谱计算所得产甲烷菌群Shannon多样性指数、Margalef丰富度指数和Berger-Parker优势度指数没有差异,表明基于2种目标基因的产甲烷菌群多样性分析基本一致.基于不同目标基因的优势产甲烷菌群系统发育种属的分析结果大体相似,产甲烷杆菌目和产甲烷八叠球菌目是厌氧颗粒污泥样品中的优势产甲烷种群;同时,分析结果的差异表明2种目标基因的检测特异性不完全相同.基于2种目标基因的产甲烷菌群FISH杂交区域具有很高的一致性,但杂交区域面积有所差异.基于mcrA基因FISH检测的产甲烷菌群平均相对丰度为24.25%±6.47%,低于基于16S rRNA基因FISH检测结果(33.42%±2.34%).以上结果表明,基于mcrA基因与基于16S rRNA基因的的产甲污泥菌群分析结果具有较高的相似度,mcrA基因可以作为16S rRNA基因的替代目标基因.     

Structure and function of rhizosphere and non-rhizosphere soil microbial community respond differently to elevated ozone in field-planted wheat

To assess the responses of the soil microbial community to chronic ozone (O₃), wheat seedlings (Triticum aestivum Linn.) were planted in the field and exposed to elevated O₃ (eO₃) concentration. Three treatments were employed: (1) Control treatment (CK), AOT40 = 0; (2) O₃-1, AOT40 = 1.59 ppm•h; (3) O₃-2, AOT40 = 9.17 ppm•h. Soil samples were collected for the assessment of microbial biomass C, community-level physiological profiles (CLPPs), and phospholipid fatty acids (PLFAs). EO₃ concentration significantly reduced soil microbial carbon and changed microbial CLPPs in rhizosphere soil, but not in non-rhizosphere soil. The results of the PLFAs showed that eO₃ concentrations had significant effects on soil community structure in both rhizosphere and non-rhizosphere soils. The relative abundances of fungal and actinomycetous indicator PLFAs decreased in both rhizosphere and non-rhizosphere soils, while those of bacterial PLFAs increased. Thus the results proved that eO₃ concentration significantly changed the soil microbial community function and composition, which would influence the soil nutrient supply and carbon dynamics under O₃ exposure.     

pH对过一硫酸氢盐湿法氧化去除甲硫醇恶臭气体的影响

以过一硫酸氢盐(PMS)作为氧化剂,利用化学吸收氧化法去除甲硫醇(CH3SH)恶臭气体.研究了p H(2~13)对CH3SH吸收过程、PMS氧化降解CH3SH过程的影响.结果表明,PMS不同于H2O2,在p H小于CH3SH p Ka(10.3)的弱碱性条件(p H=8~10)下,也可以有效去除CH3SH,而此时H2O2对CH3SH没有去除效果.可能的原因是,在弱碱性条件(p H=8~10)下PMS或可能产生的活性物种在气液相界面直接快速氧化CH3SH分子.