三峡库区夏季万州段底泥甲烷功能菌群落对甲烷排放的影响

三峡水库是世界上最大的人工水库,其潜在甲烷释放近年来备受关注。目前将甲烷排放量与甲烷功能菌的生长与作用机制相结合开展研究的报道较少。为探究三峡库区夏季万州段甲烷功能菌群落对甲烷排放的影响,分别于2019年7月和9月采集了三峡库区万州段底泥,利用16S rRNA基因高通量测序技术,对该区域的万州干流和高阳、黄石支流在属水平上的甲烷功能菌群落组成结构以及甲烷功能菌群落与甲烷排放通量间的关系进行了研究。结果表明：监测期间内高阳、黄石、万州平均甲烷通量为(0.874±0.011)、(0.884±0.234)、(0.507±0.262) μmol·(m²·h)⁻¹,支流大于干流,总体表现为甲烷排放“源”。在产甲烷菌群落中,部分未分类产甲烷古菌unclassified_p_Euryarchaeota、environmental_samples_f_ Methanosarcinaceae以及未命名古菌对产甲烷影响较大,该类细菌可促进甲烷产生。在甲烷氧化菌群落中,Methylobacter、Methylosarcina以及未分类氧化菌对甲烷氧化有较大影响,当该类细菌占比增加时会加速甲烷氧化,从而减少水-气界面中的甲烷排放。除甲烷功能菌群以外,推测温度与河流回水顶托作用也是导致干、支流甲烷排放出现差异的重要因素。以上研究结果可对揭示水库甲烷排放与甲烷功能菌生长和作用机制的关系提供参考。     

污泥与餐厨垃圾联合厌氧发酵产氢余物产甲烷条件优化研究

研究了21、37和47 d产甲烷物料代替新鲜污泥接种于污泥与餐厨垃圾联合厌氧发酵产氢余物的厌氧发酵产甲烷情况,发现接种47 d产甲烷物料的消化系统在最佳接种量50%条件下的产甲烷效能显著优于接种新鲜污泥的消化系统,不仅提高了产甲烷率,还大大缩短了消化时间。并且3种消化系统产甲烷率和比产甲烷率均为47 d37 d21 d,分别为3.78、3.88、6.15 mL/g和0.172、0.277、0.559 mL/(g·d),完成产甲烷过程的消化时间为47 d37 d21 d。在一定的消化时间范围内,产甲烷菌被驯化时间越长,接种于产氢余物中的产甲烷效能越好。     

长链脂肪酸对餐厨垃圾厌氧消化产甲烷的影响

为研究中温条件下长链脂肪酸（LCFA）的含量及代谢对餐厨垃圾厌氧消化过程的影响,考察了LCFA添加量分别为0、0.6、1.2、1.8、2.4、3和3.6 g·L-1条件下产沼气量、累积甲烷产量以及代谢中间产物挥发性脂肪酸/乙醇的浓度和组成。结果表明：在中温餐厨垃圾厌氧产甲烷的过程中,虽然LCFA也能够被微生物代谢转化生成甲烷,但LCFA的存在会对产甲烷过程造成一定程度的抑制作用;当其含量较低时抑制作用较为微弱,当其含量较高（>2.4 g·L-1）时,甲烷产量及产甲烷速率都会受到较大影响;特别是当LCFA含量高于3.6 g·L-1时,体系出现较强的抑制现象。通过实验累积值与理论甲烷产率的对比可以发现,LCFA含量越高的反应器中实验累积值/理论值的比值越低,表明有机物的转化效率越低。通过对厌氧过程中间产物的检测可知,LCFA含量越多的反应器中初期累积的挥发性脂肪酸浓度越高,当反应体系的LCFA浓度超过2.4 g·L-1时,累积的乙酸和丙酸浓度较高,丙酸降解过程和乙酸代谢产甲烷的过程受到一定程度的延滞和抑制作用,降解速率低于正常水平,厌氧发酵的能力和效率受到影响。     

垃圾填埋场甲烷氧化菌及甲烷通量的研究

采用静态箱法、滚管计数法和气相色谱法,对6个不同封场时间填埋区的甲烷通量、覆土层甲烷氧化菌数量和甲烷氧化速率的变化趋势进行了测定,并分析了它们与封场时间、植被覆盖率等因素之间的相关性。结果发现6个填埋区甲烷通量的变化范围在-0.34～5.31 mg/(m2.h)之间;覆土层甲烷氧化菌的数量范围为3.10×107～20.77×107 cfu/g干土,甲烷氧化速率在1.65×10-8～4.34×10-8mol/(h.g)之间。覆土层甲烷氧化菌的数量与甲烷氧化速率呈正相关,但前者并不是后者的决定性因素;甲烷通量高时可刺激甲烷氧化菌数量及氧化速率的提高,且三者均与封场时间呈显著负相关,与植被覆盖率呈负相关;当含水率大于15%时,随着覆土层含水率的增加,甲烷氧化速率呈下降趋势;覆土pH、有机质和铵态氮与甲烷氧化速率等无明显相关性。提高覆土层的甲烷氧化速率可有效减少垃圾填埋场的甲烷排放。     

渗滤液回流对不同填埋结构甲烷变化规律的影响研究

建立了大型模拟填埋试验装置,研究了渗滤液回流对不同填埋结构甲烷变化规律的影响.每周对填埋气体中甲烷浓度进行监测.结果表明:厌氧填埋中回流操作使甲烷浓度峰值提前了147 d,峰值为59.6%(体积分数,下同);准好氧填埋中回流操作使甲烷浓度峰值提前259 d,峰值为44.7%.回流操作使甲烷产气高峰提前,增加产气量,加快填埋垃圾稳定,减轻渗滤液污染.厌氧填埋中进行回流操作有利于甲烷的回收利用;准好氧填埋结构可有效减少甲烷的排放,减小对环境的危害.稳定期的垃圾填埋体进行回流产生一定的甲烷,但浓度较低,最高仅26.0%,没有利用价值.     

不同好氧预处理方式对餐厨垃圾产甲烷的影响

为了研究不同好氧预处理方式对餐厨垃圾厌氧消化产甲烷的影响,通过建立3个模拟厌氧生物反应器,研究了传统厌氧生物反应器C1、上层好氧预处理-厌氧生物反应器C2和底部好氧预处理-厌氧生物反应器C3 3种不同操作条件下的产甲烷过程。结果表明,挥发性有机酸的累积使C1始终处于产甲烷滞后阶段;而C2、C3的好氧预处理通过加快易水解酸化组分和过量挥发性有机酸的好氧降解,有效缓解了酸性抑制,产甲烷滞后时间明显缩短至10 d内。第32天C2停止上层曝气后,在27 d内甲烷浓度达到了50%以上,同时,产甲烷速率迅速上升,并在第81天可达到峰值773 mL/(kg·d)。C3在第11天停止底部曝气后,虽然经过22 d的时间甲烷浓度即上升至50%,但之后产甲烷速率经历回落阶段后再次逐渐上升,在实验结束时仅达到517 mL/(kg·d)。上层曝气的好氧预处理方式所需曝气时间相对较长,但其产甲烷启动快,与底部曝气相比,其后期的甲烷化过程更稳定并可达到较高的产甲烷速率。     

Theoretical consideration of methane emission from sediments

A stationary theory of gas emission from sedimentary (active) layers of wetlands is developed. The theory takes into account methane generation in a sedimentary layer (W1) and its depth dependence, (W1(z)), the solubility, determined by Henry's constant (K1), and the mobility of methane molecules set by the methane diffusion coefficient (D1). The exponential dependence of methane generation rate decay with depth is considered in more detail. The penetration of atmospheric nitrogen into the active layer is also taken into consideration. It is shown that the value of diffusion methane flux from sedimentary layers is proportional to square root(K1D1P0W10) where P0 characterizes the atmospheric pressure and W10 characterizes the maximum generation rate. Coefficients relating the diffusion methane flux to the square root(K1D1P0W10) value are calculated for the different depth dependencies of methane generation rate. The values of these coefficients are not much different from unity for most real cases.     

甲烷氯化物废水治理工艺的技术应用

在氯碱工业加工过程中会产生大量的甲烷氯化物废水,废水中含有大量的甲烷氯化物,该类废水不易处理,极大地影响了后续废水处理工作的开展。本文以某司甲烷氯化物具体试验为例,探讨高分子吸附剂在甲烷氯化物废水处理过程中的应用,在利用高分子吸附剂进行吸附的同时通过蒸汽吹脱使树脂中富集下来的甲烷氯化物得到分离回收,从而实现了废水的资源化,达到治废与资源利用的双重效果。     

Influence of plants on the methane emission from sediments

The previous theory [Chem. Global Change Sci. 3 (2001) 33; Chemosphere 50 (2003) 191] of methane emission is applied to vegetated sediments. The presence of roots in a sediment is taken into account. It is assumed that methane and nitrogen enter a sediment through channels existing in plants and roots. The rate of methane and nitrogen transport through plants and roots is proportional to the difference in concentrations in the layer and on the upper surface. It is established that as the vegetation density increases, the rate of methane transport increases so that with sufficient vegetation density, almost all methane passes to the atmosphere through plants. In this case, the value of bubble emission decreases to zero. The nitrogen transport rate through plants first increases and then decreases with increasing the vegetation density. The theory qualitatively and quantitatively describes the dependence of methane concentration on depth in the presence of plants. A comparison with the available experimental data on dissolved methane concentration and bubble composition indicates satisfactory agreement.     

基于系统动力学模型的城市生活污水处理系统的甲烷排放特征及减排潜力分析

为全面了解我国城市生活污水处理系统的甲烷排放现状及未来趋势,根据政府间气候变化专门委员会(IPCC)清单计算方法核算了2000—2015年我国生活污水处理系统的甲烷排放量。基于嵌入中国生活污水处理系统甲烷排放IPCC清单计算方法的系统动力学(SD)模型,模拟分析了2015—2050年基线情景和7种减排情景下的甲烷排放达峰和减排潜力。结果表明：我国生活污水处理系统甲烷排放总量从2000年的32.15×10⁴ t升至2015年64.78×10⁴ t,其中,污水处理过程中的甲烷排放量增长迅速,生活污水直接排入自然水体及经过处理后排放的甲烷排放量无明显增长;在模拟时段(2015—2050年)内,基线情景、节约用水情景、污水回用情景和节水回用情景中未出现生活污水处理系统甲烷排放峰值,在污水产生源头采取减排措施只能减缓增长速度,无法达到甲烷排放峰值;不同情景下的甲烷排放达峰时间及峰值不同,单一减排情景下的甲烷排放峰值出现在2035年后,而组合减排情景的峰值出现在2035年前,其中全程减排情景峰值出现在2024年;单一减排情景中污水回用减排潜力较好,可将其作为减排重点方向;而组合减排情景中全程减排情景具有最大减排潜力。本研究表明,未来生活污水处理系统甲烷排放量仍呈不断上升趋势,采用多手段协同减排可实现预期时间内污水处理系统甲烷排放达峰.     

昆明市污水排水系统产甲烷规律的模拟实验研究

通过对昆明市餐饮和居民生活污水厌氧模拟实验研究,初步探讨生活污水中CH4的产生规律,实验结果表明,在自然条件下,餐饮和居民生活污水中产生的甲烷浓度最大值分别为1.63 mg/L和3.82 mg/L。并且将COD、硫酸盐、硫化物、TN的浓度变化与甲烷浓度变化进行Pearson简单相关性分析,结果表明,1/COD、COD/硫酸盐和1/TN与甲烷在置信度为0.01时极显著相关,硫化物与甲烷在置信度为0.05时不相关;COD、硫酸盐和TN浓度的变化对生活污水中甲烷的产生起关键性作用。对居民生活污水中甲烷产生规律进行温度和pH控制分析研究,实验结果表明,生活污水在25~30℃时,24 h内甲烷产生量最大值为8.6494 mg/L,明显大于其他温度段的甲烷产生量;在pH为7~8之间时,甲烷的产生量在24 h内达到的最大值为3.0477 mg/L,明显高于其他pH控制段的甲烷产生量。     

Continuous Monitoring of Methane and Other Hydrocarbons In Urban Atmospheres

Continuous measurements of total hydrocarbons (and other organic substances) and of methane were made in Cincinnati and Los Angeles for three-month periods. Some of the measurements were made during episodes of photochemical air pollution. Two instruments, one for measurement of total hydrocarbons and the other for methane, were operated in parallel. Both incorporated flame ionization detectors having greater sensitivity than commercial flame ionization instruments. The flame ionization analysis for methane was made specific by use of an adsorbent carbon column preceding the analyzer to retain all organic substances except methane. Subtracting the methane concentration values from those for total hydrocarbons gave nonmethane hydrocarbon concentrations. The data showed diurnal patterns of concentrations of methane and nonmethane hydrocarbons in the atmosphere. Average hourly values for methane were strikingly similar in Los Angeles and in Cincinnati (2.6 and 2.4 ppm, respectively); those for nonmethane hydrocarbons were four times as high in Los Angeles (3.0 and 0.8 ppm, respectively). A bimodal frequency distribution pattern of the concentrations suggested that atmospheric ventilation was either good or poor, with less than a random amount of time in intermediate stages. The width of the methane frequency distribution peak was about half the width of that for nonmethane hydrocarbons, indicating a different and more constant source for the former.     

基质组分对厨余与污泥共发酵动力学特性的影响

通过厌氧发酵4阶段动力学实验、产甲烷抑制实验及单一VFA的产甲烷动力学实验,探明了厨余和污泥共发酵过程中,典型组分对其潜在的酸积累类型以及甲烷化过程的影响。结果表明,不同基质组分在厌氧发酵过程中的VFA组成比例以及单一VFA的产甲烷化动力学特性,对其产甲烷潜能及速率有着决定性影响。乙酸的甲烷化速率高达44.80 mL·d-1,丁酸略慢于乙酸,而丙酸和戊酸的甲烷化速率不足乙酸的1/2,其中丙酸的延滞期长达1.76 d。因此,产酸类型以乙酸为主的污泥、菜类在产甲烷阶段不存在延滞期;而蛋肉类及油的产甲烷速率受到丙酸、戊酸动力学特性的影响相对较慢。通过调整共发酵基质配比不仅能够提高发酵潜能,还能够优化VFA组成比例,实现较高的甲烷产率及甲烷化速率。     

模拟生物反应器加速产甲烷过程研究

渗滤液原液回灌易导致填埋垃圾产甲烷过程的滞后,从而对甲烷收集利用产生不利影响。通过3根实验室模拟生物反应器,研究了原液回灌(C1)、渗滤液好氧预处理后回灌(C2)和原液回灌+垃圾层上部通风曝气(C3)3种填埋方式下的填埋气产气规律。结果表明,C1甲烷浓度经历短暂上升,达到19.5%后开始逐渐降低,产甲烷速率和产甲烷总量均很低;C2甲烷浓度逐渐上升,在第121天时甲烷浓度达到50%,产甲烷最高速率和产甲烷总量分别为0.31 L/(kg·d)和25.2 L/kg。在停止上部垃圾层通风曝气后,C3甲烷浓度迅速上升,在81 d时甲烷浓度便达到50%以上,最大产甲烷速率和产甲烷总量分别为0.22 L/(kg·d)和16.0 L/kg。对各模拟柱填埋气可回收性评价结果表明,C3填埋气可回收利用比例最高,C2略低,C1在实验期间内则无可回收利用气体产生。     

Methane oxidation by Dutch grassland and peat soil microflora

The ability of Dutch grassland soil and Dutch peat soil for methane oxidation was investigated. The kinetics of methane oxidation by soil from different depths were determined in batch cultures incubated with 1; 10; 100; and 10,000 ppmv methane, respectively. All 4 applied concentrations of methane were degraded by both types of soil. Thereby, the highest oxidative activities were observed between 5 and 10 cm soil depth. Most importantly, these experiments demonstrated that this soil acts as a sink for methane even at concentrations well below 1 ppmv. Especially at higher methane concentrations (100 - 10,000 ppmv) much higher degradation rates were found in the peat soil. This also correlates with the higher methane production rates which had been observed in peat soil.     

Reconstruction of the methane fluxes from the west Siberia gas fields by the 3D regional chemical transport model

A 3D mesoscale tropospheric photochemical transport model of high spatial resolution has been developed and used for assessment of the methane concentrations and methane emission in the West Siberian region of intensive mining of natural gas and oil deposits. The model is validated against the measurements of methane concentration at the surface and in the lower troposphere collected during July 1993 and June 1996 experiments. Comparison of the simulated and observed concentrations allowed to estimate that during the above periods the average natural methane fluxes were as high as 65 mg m⁻² day⁻¹. The anthropogenic methane fluxes (leakage from gas deposits) integrated over model domain during the same time period were about 20% of the total methane emission from relevant areas.     

初始pH值对氨三乙酸促进产甲烷效果的影响

金属离子螯合剂氨三乙酸(nitrilotriacetic acid, NTA)可提高微量金属离子的生物可用性,促进厌氧消化产甲烷。借助气相色谱分析,在探讨系统酸性pH值对厌氧消化甲烷产量影响的基础上,重点研究了初始pH值对NTA促进产甲烷效果的影响。结果表明,系统初始pH值对厌氧消化产甲烷有一定的影响,其影响程度与溶液中游离乙酸的浓度密切相关。NTA对产甲烷的促进作用在pH值为6.5和7.0时较为明显,而在更低pH条件下,几乎没有促进作用。当pH为7.0、添加10 μmol/L NTA时,与对照样相比,累积甲烷产量增加了38.5%,而pH 6.0时,作用却不明显。     

牛粪和玉米秸秆厌氧消化产甲烷潜力及动力学

为了评价牛粪和玉米秸秆的产甲烷潜力,研究其厌氧消化过程动力学方程,采用自制序批式厌氧发酵实验装置对某养殖场牛粪和秸秆的最大甲烷生产潜力及其发酵过程进行研究。通过实验研究,测得接种物、牛粪和玉米秸秆的累计甲烷产量分别为64.87、244.0和466.54 mL CH4/g VS。根据实测的产气量变化曲线,按照modified Gompertz equation模型进行方程拟合,牛粪组和玉米秸秆组拟合方程的相关性系数分别为0.983和0.991,表明运用modified Gompertz equation模型预测牛粪和玉米秸秆的产甲烷潜力方法可行。通过对产甲烷过程的动力学研究得到:接种物、牛粪和玉米秸秆的最大产甲烷潜力分别为66.07、213.93和458.57 mL CH4/g VS,与实测值的误差率分别为1.8%、12.3%和1.7%;牛粪和玉米秸秆的最大甲烷日产气率(Rm)和延滞期时间(λ)分别是13.14 mL CH4/(g VS·d)、30.76 mL CH4/(g VS·d)和0.35 d、0.71 d。综上,玉米秸秆厌氧消化的停滞期长,但总产气量和最大甲烷日产期率都比牛粪高。     

Methane emissions from peat bogs in the vicinity of the Mace Head Atmospheric Research Station over a 12-year period

Methane emissions from the peat bogs in Connemara, Ireland have been inferred from the trace gas observations at the Mace Head Atmospheric Research Station using the nocturnal box method. A total of 237 local events, during April to September, over a 12-year period have been studied. Simultaneous emissions of methane, carbon dioxide and chloroform are routinely observed under nocturnal inversions with low wind speeds from the peat bogs proximal to Mace Head. Night-time deposition of ozone and hydrogen occurs concurrently with these emissions. Using the temporally correlated methane and ozone data we estimate methane emissions from each event. Simultaneous methane and chloroform emissions, together with ozone and hydrogen deposition have been characterised, leading to the estimation of methane emission rates for each event. The mean methane emission flux was found to be 400 ± 90 ng m^?2 s^?1. A strong seasonal cycle was found in the methane emission fluxes but there was little evidence of a long-term trend in the emissions from the peat bogs in the vicinity of the Mace Head station.