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.     

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 .     

过二硫酸盐降解碱液吸收的甲硫醇恶臭

甲硫醇(CH3SH)是一种高毒、高腐蚀性的酸性气体,是恶臭的重要组成部分.碱液吸收是最常用的CH3SH处理方法之一,但吸收液需要进一步处理.过二硫酸盐(persulfate,PS)作为氧化剂用于降解碱液吸收的CH3SH尚鲜见报道.为此,建立一连续循环的吸收降解体系,进行CH3SH的碱液吸收及PS降解实验,并探讨了PS在碱性条件下的稳定性,及反应条件对CH3SH吸收和降解动力学的影响.结果表明,PS在碱液中的稳定性较好,能够有效地降解碱液吸收的CH3S-;随着PS浓度的增加,CH3SH的吸收速率呈先增加后减小的趋势,CH3S-的降解速率不断增大;随着pH的增加,CH3SH的吸收和降解效果均明显增加.在pH为12,CH3SH进气浓度80 mg·m-3,进气速率1.5 L·min-1,PS浓度为1.4 g·L-1时,碱液吸收的CH3S-90%被降解.     

有机硫恶臭物质采样和分析检测技术研究

本研究以二甲二硫醚和甲硫醇为代表对有机硫恶臭物质的采样浓缩,热解析和ＧＣ,ＧＣ／ＭＳ的色谱分离,定性鉴定和定量检测方法进行了实验技术研究。与此同时研制开发了恶臭污染监测的系列配套装置－采样管,微型采样泵,热解析色谱进行装置和标准气体物质发生装置。经筛选确认,国产ＧＤＸＥ１０５采样管可对ＤＭＤＳ和ＣＨ３ＳＨ实现直接常温采样浓缩,样品回收率分别为１００％和６０％。ＧＣ／ＦＰＤ对二种硫化物的检出下限分别     

Design of a straight inlet diffusion scrubber. Comparison of particle transmission with other collection devices and characterization for the measurement of hydrogen peroxide and formaldehyde

Particle deposition characteristics of several diffusion scrubber (DS) designs of annular geometry were studied and a straight inlet geometry was selected for further performance evaluation. At sample flow rates of 1–5 ℓ min⁻¹, 5–17% of Boltzmann charged 0.1–3 μm aerosol is deposited in the device, with 0.5–2.5% deposition on the membrane tube, the central collecting element. Most of the wall deposition appears to be due to electrostatic effects caused by the PTFE wall; this is accentuated by dry air (⩽5% r.h.) test conditions. Significant deposition loss is observed with glass denuders under the same test conditions as well. Extensive performance tests were made with the new geometry DS; Nafion® membrane based DS devices are recommended for the measurement of H₂O₂ and HCHO. For NH₃, reasonably fast response times are difficult to attain with Nafion membrane DS devices, however. Some unexpected new findings regarding the transmission of acid gases through a Nafion membrane and their implications are discussed.     

GC determination of dimethyl selenide and trimethyl selenonium ions in aquatic systems using element specific detection

Dimethyl selenide has been postulated to be an organoselenium compound in seawater. In this study, dimethyl selenide was detected in seawater along with a non-identified sulfur compound other than COS, CH₃SH, CS₂, DMS, and DMDS. Additionally, trimethyl selenonium ions could be detected in a moorland lake water sample.     

铁活化过二硫酸盐湿法氧化去除一甲胺恶臭气体

CH₃NH₂(一甲胺)作为一种重要的工业原料而被大量使用,其嗅阈值低,具有刺鼻的鱼臭味,是一种典型的恶臭气体. 选取PS(过二硫酸盐)作为氧化剂,采用湿法吸收氧化去除CH₃NH₂. 在探讨CH₃NH₂的吸收性能的基础上,比较了4种方式〔Fe2+活化PS、CA(柠檬酸)螯合Fe2+活化PS、Fe0活化PS、CA联合Fe0活化PS〕对CH₃NH₂湿法氧化去除效果的影响. 结果表明:CH₃NH₂ 气体在酸性条件下易溶于水;单独用Fe2+或Fe0活化PS处理CH₃NH₂时,Fe0活化后的去除效果明显优于Fe2+;然而,在联合使用螯合剂CA之后,Fe2+活化的去除效果反而优于Fe0. CA螯合Fe2+的CH₃NH₂去除率由单独Fe2+活化时的32%升至64%,Fe0活化与CA联合Fe0活化去除率均提升至40%. 究其原因,可能是由于不同活化方式下Fe2+释放速率不同所致,释放速率直接影响了Fe2+的存在时间,Fe2+活化PS速率对于氧化去除效果有影响,并最终影响CH₃NH₂的脱除.      

生物水解法处理尿素废水

一、概述 尿素合成反应中,每生成1mol尿素同时生成1mol水,加上其它工艺过程排出的水,化肥厂每生产一t尿素大约要排放0.5—0.7t工艺废水,其中含有1—2％的尿素,2—5％的氨。通常先将这股水进行解吸以回收     

Deposition and forest canopy interactions of airborne sulfur: Results from the integrated forest study

The Integrated Forest Study (IFS) was a long-term research project designed to determine the effects of atmospheric deposition on forest nutrient cycles. Concentrations and fluxes of airborne sulfur compounds were determined for several years at the 13 IFS research forests in North America and Europe using a standard set of protocols. Annual mean air concentrations of sulfur ranged from ∼1.5 to 8 μgSm⁻³ and were generally dominated by SO₂ (∼60% of total sulfur on the average). Atmospheric deposition of sulfate at these forests was highest at the high elevation (∼ 1000–2000 eq ha⁻¹yr⁻¹) and at the southeastern U.S. sites (∼800–1000 eq ha⁻¹yr⁻¹), and lowest in the Pacific northwest (∼300 eq ha⁻¹yr⁻¹). Cloud water contributed significantly to the sulfur flux at the mountain sites (45–50%), and dry deposition was comparable to wet at the drier southeastern sites (>40% of total). Deposited sulfur appeared to behave more or less conservatively in these canopies, showing little net uptake (ofSO₂) and minor foliar leaching (of soil-derived, internal SO₄²⁻) relative to the total atmospheric flux. The estimated fluxes in total deposition were generally within 15% of the measured fluxes in throughfall plus stemflow, indicating that useful estimates of total atmospheric deposition of sulfur can be derived from measurements of throughfall.     

节水灌溉模式对稻田CH4排放规律的影响

基于水稻节水灌溉技术和密闭静态箱技术田间原位采集甲烷气样,试验研究了水稻节水控制灌溉模式对稻田CH₄排放规律的影响.结果表明,控制灌溉稻田CH₄排放呈现明显的下午极大值型日变化,CH₄排放高峰主要出现在下午13:00,淹水处理CH₄排放峰值在1 d中各个时刻的出现具有一定的随机性.控制灌溉稻田CH₄排放呈现明显的单峰型季节排放规律,排放高峰发生在分蘖前期,比淹水处理提前了10 d.所以,控制灌溉模式在水稻返青期后的水分调控及生产性用水等水管理措施对稻田CH₄排放的影响至关重要.控制灌溉水稻全生育期的稻田CH₄排放总量为24.46 g·m^-2,比淹水稻田减少了39%,平均排放率为7.96 mg·(m²·h)^-1,但返青期和分蘖前期的CH₄平均排放率比淹水稻田高,在以后的各个生育阶段均低于淹水稻田.     

盐碱区不同开发年限水田温室气体排放规律及影响因素

以吉林省前郭盐碱水田区为研究对象,采用野外采样和小区试验相结合的方法,监测水稻生长期土壤温室气体(CH4和N2O)排放、土壤p H和土壤有机碳(SOC)变化,分析水田温室气体排放规律及其影响因素.结果表明,水田N2O排放季节变化特征明显并呈现3个峰值,肥料的施入提供了更多的反应底物,对水田N2O的排放量影响显著.在淹水条件下,N2O的主要来源于反硝化过程,而排水后,硝化作用则占据了主导地位.CH4排放呈现单峰,在水稻生长旺盛的分蘖期,稻田较深水层以还原环境为主,为产生CH4的微生物提供了适宜的条件,进而导致CH4排放呈高峰值;土壤p H对N2O和CH4排放的影响不明显,但土壤SOC含量与CH4的排放规律呈现显著正相关.     

The near U.V. absorption spectra of dimethyl sulfide,diethyl sulfide and dimethyl disulfide at T=300 K

Absorption cross-sections are reported for dimethyl sulfide (CH₃SCH₃), diethyl sulfide (C₂H₅SC₂H₅), and dimethyl disulfide (CH₃SSCH₃) at wavelengths greater than 200 nm, a temperature of 300 K, and a nominal spectral resolution of 0.10 nm. In general, the results are in good agreement with previous measurements of the spectra of these molecules, but are of higher precision and resolution than past measurements. New features in the spectra, including a previously unobserved vibrational progression for diethyl sulfide, are discussed. Finally, the data are used to calculate a photodissociation lifetime for dimethyl disulfide, the only one of the three molecules that absorbs light in the actinic u.v. region of the spectrum. Loss of dimethyl disulfide by photodissociation is expected to be 5 – 10 times slower than loss due to reaction of the compound with OH under atmospheric conditions.     

河口潮滩湿地CH4、CO2排放通量对氮硫负荷增强的响应

以闽江河口区高、中潮滩短叶茳芏湿地为研究对象,于2014年6—11月植物生长季进行氮硫负荷增强实验,利用静态箱-气象色谱法测定土壤CH_4、CO_2排放通量,并同步观测相关环境因子.结果表明,氮硫负荷增强对潮滩湿地CH_4、CO_2排放通量的影响不尽一致.与对照相比,NH_4~+-N输入使高、中潮滩CH4排放通量分别提高了(107.53%,7.19%),使高潮滩CO_2排放通量增加了3.39%,中潮滩减少了3.00%;NO_3~--N输入使高潮滩CH4、CO_2排放通量分别增加了(29.99%,16.99%),使中潮滩分别减少了(3.45%,4.77%);SO_4~(2-)-S输入使高、中潮滩CH4排放通量分别减少了(8.99%,7.67%),使高潮滩CO_2排放通量减少了3.87%,中潮滩增加了5.44%;N-S复合输入使高、中潮滩CH4排放通量分别提高了(72.48%,25.66%),CO_2排放通量提高了(13.32%,13.48%).氮硫负荷增强改变了短叶茳芏沼泽生长季CH_4、CO_2排放通量变化规律,但除了NH+4-N处理对高潮滩CH4通量的影响显著外,其他处理影响均未达到显著性水平.相关分析显示,高、中潮滩湿地CH_4、CO_2排放通量与土壤温度,含水率具有显著的正线性相关关系,与土壤电导率相关性不显著.在全球环境问题日益严重背景下,系统研究湿地生态系统温室气体排放的机制与规律,对于准确估算全球温室气体排放量具有重要而直接的意义.     

The response of a mid- and high latitude peat bog to predicted climate change: methane production in a 12-month peat incubation

There are fears that global warming will lead to degradation of peatlands, higher emissions of greenhouse gases from peat, and accelerated warming. Anaerobic decomposition of organic soils produces methane (CH₄), a potent greenhouse gas. Two peat bogs differing in mean annual temperature, Velke Darko (VD, Czech Republic, 7.2 °C), and Stor Åmyran (SA, Sweden, 4.0 °C), were selected for a comparative study of how organic soils in different climatic zones will respond to warmer and drier conditions. Twenty peat cores from each bog were incubated in growth chambers. Under present-day summer conditions, VD produced 14 times more CH₄ than SA. Two different warming scenarios were used. Peat-core replicates were kept at temperatures of 11 versus 16 °C, and 11 versus 22 °C. From 11 to 16 °C, the CH₄ production slightly decreased at SA, and slightly increased at VD. From 11 to 22 °C, the CH₄ production increased 9 times at SA, but slightly decreased at VD. After an 8-month incubation, peat cores under drying conditions (water table at ?14 cm) were compared to samples with original water table (?2 cm). Drying conditions led to a steeper reduction in CH₄ production at VD, compared to SA. The CH₄ production decreased more than 100 times at VD. Then, the combined effect of simultaneous warming and drying at 11 and 22 °C was studied. We did not find any significant effect of interactions between increasing temperature and decreasing water table level. Overall, the warmer site VD responded more strongly to the simulated climate change than the colder site SA.     

O3/UV反应体系的有机物消解动力学模型

为了提高O₃/UV（臭氧协同紫外）反应体系对有机物的消解效率,降低能源消耗,基于O₃分解的SHB机理和O₃、有机物在紫外辐射下的光解机理,并考虑该反应体系中存在的3种可能的有机物消解途径和反应器出口处O₃气体浓度变化,建立了O₃/UV反应体系的动力学模型.将该模型用于消解过程中有机物消解率变化规律的研究,进一步优化消解工艺参数.结果表明:使用苯酚和乙酸作为目标有机物,以该模型进行仿真,从理论上验证了O₃气体浓度与紫外辐射间存在协同作用和不同工艺参数下所建立模型的灵敏性;将该模型与其他模型、试验测量值进行对比,验证了其优越性和准确性;对比不同pH下的3种消解途径各自贡献率的仿真结果,发现O₃/UV反应体系的pH对其消解有机物效率具有重要影响.研究显示:在O₃/UV反应体系中,紫外辐射强度和投加的O₃气体浓度二者间具有协同作用,同时调节可获得更好的消解效果;在酸性条件下有机物消解以O₃直接氧化为主,碱性条件下则以自由基间接氧化为主.      

Observation of possible elemental sulfur in the marine atmosphere and speculation on its origin

Samples obtained during research cruises in the North Atlantic and the North Pacific showed possible evidence of gas-phase elemental sulfur, S₈. Though the sampling and analytical method are still untested for this sulfur species, these data represent the first suggestion that this sulfur species exists in the marine troposphere. Concentrations of S₈ were ∼ 1 ng m⁻³ or less, though these measurements may represent a lower limit of the true ambient concentration. Though there are only few data, concentrations of elemental sulfur appear to be elevated near coastal or continental margins in the North Atlantic. Possible sources of elemental sulfur include direct vaporization during the sulfur processing, automotive emissions, geothermal emissions, and heterogeneous oxidation of reduced sulfur in cloud droplets.     

三峡澎溪河水华期间水体CH4浓度及其通量变化特征初探

三峡库区温室气体的排放近年来备受关注.为了揭示三峡库区澎溪河地区水华过程中不同氮磷浓度下藻类生长死亡过程中CH₄吸收释放的规律,于2016年4月22日至2016年5月9日,通过添加不同氮磷浓度在澎溪河高阳平湖水域展开野外原位实验.结果表明,在开始实验当日CH₄通量从（1.8093±0.0632）μmol·（m²·h）^-1到6 d急剧减少至（0.0776±0.0146）μmol·（m²·h）^-1.6 d后变化相对较小,相比较于其他水样只添加磷的水样明显有所回升.在本次实验中藻类的生长与死亡受到了不同N、P浓度梯度的影响.N对藻类的生长影响不大,各种指标与未加N、P营养盐的原水基本一致;在适宜的P浓度下,促进藻类的生长.当P浓度过多时,藻类的生长受到抑制.水样中的CH₄通量的吸收与释放和添加的硝态氮有关.     

Methane and nitrous oxide emissions from an integrated rainfed rice–fish farming system of Eastern India

Integration of fish stocking with rice (Oryza sativa L.) cultivation promises an ecologically sound and environmentally viable management of flooded ecosystem. Rice agriculture contributes to the emission of greenhouse gases CH₄ and N₂O, but little is known on the effect of fish rearing in fields planted to rice on the emission of these two greenhouse gases. In a field study, CH₄ and N₂O fluxes were measured from a sub-humid tropical rice field of Cuttack, eastern India, as affected by integrated rice–fish farming under rainfed lowland conditions. Three Indian major carps, Catla catla H., Labeo rohita H. and Cirrhinus mrigala H., and Puntius gonionotus B. were stocked in rice fields planted to two rice cultivars in a split-plot design with no fish and fish as the main treatments and two rice varieties as sub-treatments with three replicates each. Fish rearing increased CH₄ emission from field plots planted to both the rice cultivars with 112% increase in CH₄ emission in cv. Varshadhan and 74% in case of cv. Durga. On the contrary, fish stocking reduced N₂O emission from field plots planted to both the rice varieties. Movement of fish and associated bioturbation coupled with higher dissolved organic-C and CH₄ contents, and lower dissolved oxygen could be the reasons for release of larger quantities of CH₄ from rice + fish plots, while higher dissolved oxygen content might have influenced release of more N₂O from the rice alone treatment. The total greenhouse gas emission, expressed as CO₂ equivalent global warming potential (GWP), was considerably higher from rice + fish plots with CH₄ contributing a larger share (91%) as compared to rice alone plots (78–81%). On the contrary, N₂O had a comparatively lesser contribution with 19–22% share in rice alone plots that was further reduced to 9% in rice + fish plots. However, considering the profit-loss analysis based on the market price of the produce, rice–fish system provided a net profit of $453.36 ha^?1 over rice alone system in spite of higher carbon credit compliance of a rice–fish ecosystem due to larger cumulative GWP.     

鄂南棕红壤区不同植茶年限茶园CH4通量特征

于2014年3月—2015年12月,采用静态箱-气相色谱法测定了鄂南棕红壤丘陵区茶园和樟树林地土壤CH_4通量,研究了不同植茶年限茶园及临近林地土壤CH_4通量特征.结果表明,不同植茶年限对茶园土壤CH_4通量有显著影响,中、低龄茶园土壤CH_4以排放为主,植茶20 a和植茶8 a茶园土壤CH_4累积排放量分别为0.26和0.27 kg·hm~(-2),高龄茶园和对照林地土壤CH_4以吸收为主,植茶50 a茶园和林地土壤CH_4累积吸收量分别为0.39和1.95 kg·hm~(-2).降雨促进了鄂南棕红壤丘陵区茶园和林地土壤CH_4排放,除了植茶8 a茶园外,高、中龄茶园和樟树林地土壤CH_4通量均与7 d累积降雨量呈显著的正相关关系.施肥造成了茶园土壤CH_4排放量增加,同时土壤中矿质氮类型对该地区茶园和林地土壤CH_4通量有不同影响,CH_4排放通量与土壤硝态氮含量呈显著正相关关系,而与铵态氮含量相关关系不显著.研究表明,降雨量是影响鄂南红壤丘陵区茶园和林地土壤甲烷通量的主要因素;随着茶园种植年限的延长,土壤CH_4排放通量呈降低的趋势,高龄茶园土壤为大气CH_4汇.