珠江三角洲典型生态系统有机含硫气体地气交换通量比较

选取珠江三角洲森林、稻田和城市草地和菜地为研究对象,运用静态箱法,测量土壤COS、DMS、CS2和DMDS通量,并分析了环境因子对含硫气体交换速率的影响。结果表明,稻田和菜地交换速率最大,城市草地次之,森林土壤交换速率最小。森林土壤吸收COS,释放DMS,有凋落物土壤气体交换速率高于无凋落物土壤,CS2和DMDS源与汇存在很大不确定性。森林COS通量受温度、土壤含水量、土壤肥力、土壤微生物和土壤呼吸的共同影响;有水稻稻田吸收COS,无水稻稻田释放COS,有水稻稻田DMS释放速率显著高于无水稻稻田。干旱稻田土壤吸收COS,水淹土壤释放COS,但DMS、CS2和DMDS释放速率两者间无显著影响;城市草地吸收COS释放DMS,CS2和DMDS存在不确定性,有草土壤COS和DMS交换速率高于无草土壤,割草前后气体释放速率无显著变化;菜地释放VOSCs,其中DMDS占75%。     

挥发性有机硫化合物释放及对全球环境的影响

介绍了几种挥发性有机硫化合物：甲硫醚（DMS）、羰基硫（COS）、甲硫醇（MSH或CH3SH）、二硫化碳（CS2）和二甲基二硫（DMDS)从各种自然源（主要是生物源）释放的情况，并论述了有机硫气体释放对全球环境和气候的影响。着重阐述了在海洋、陆地生态系统中，各种生物硫源的释放情况和有机硫气体的迁移、转化规律。讨论了大气中痕量有机硫气体的分析方法，并提出一些建议。     

水稻土中硫酸二乙酯分解产生含硫气体的研究

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。结果从该淹水土壤中测出3种含硫气体；硫化氢（H2S），羰基硫（COS）和二甲基硫（DMS）气体。当土壤中加入硫酸二乙酯后，不仅上述3种气体的释放量增加了，而且还明显测出甲硫醇（CH3SH）和二硫化碳（CS2）。据此推测，水稻土中硫酸二乙酯的分解可能是CH3SH、CS2、COS、H2S、DMS5种气体产生释放的来源之一。在好氧条件（普通大气）下：（1）H2S和COS的释放量低于厌氧条件（充氮）。（2）CS2和CH3SH的释放量高于厌氧条件。（3）DMS的释放量不受空气中氧气含量的影响。分析了培养前后土壤pH和Eh的变化和影响。     

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 .     

青岛环境大气和海洋表层水中挥发性硫化物的测定

建立了采用预浓缩和GC FPD测定环境大气和海洋表层水中挥发性硫化物(COS、DMS和CS2)的方法.该方法对气态COS、DMS和CS2的回收率分别为(95±4)%,(86±3)%和(91±6)%(n=5),精密度分别为4 75%,8 26%和7 55%(n=5).对水体中COS、DMS和CS2的回收率分别为(86±8)%,(80±6)%和(97±12)%(n=5),精密度分别为8 17%,5 59%和11 70%.COS、DMS和CS2检出限分别为33pg,387pg和22pg.采用该方法测定了青岛近岸海域大气和表层海水中COS、DMS和CS2的浓度.结果表明,COS是近岸海域大气中主要挥发性硫化物,DMS是表层海水中最主要的挥发性硫化物.3种挥发性硫化物的浓度有明显的季节差异,夏季浓度远高于冬季浓度.     

湿地生态系统还原性硫气体自然释放研究

还原性硫气体是重要的痕量生源气体,对全球硫循环和大气化学具有重要作用。湿地是还原性硫气体的重要排放源,二甲基硫(DMS)、硫化氢(H2S)、羰基硫(COS)和二硫化碳(CS2)是湿地系统释放明显的还原性硫气体。开展湿地生态系统还原性硫气体自然释放的研究,可在全球尺度上估算还原性硫气体对大气循环的具体贡献提供基础数据。DMS、H2S和CS2的日变化规律表现为昼释放率大于夜释放率,COS释放速率表现为夜大于昼,在季节变化上都呈现生长季释放率大于非生长季;空间释放规律上也有较大差异性,水稻田硫气体释放量较为明显。温度通过影响酶活性进而影响硫气体释放,土壤、植被和潮周期等也是影响湿地生态系统还原性硫气体释放的重要因素。在探讨目前该研究领域存在不足的同时,对未来的研究工作进行了展望,以期对湿地生态系统还原性硫气体释放取得更深入的探究。     

春季东海挥发性有机硫化物(VSCs)分布的研究

于2017年3~4月首次对东海表层海水及大气中3种主要挥发性有机硫化物（VSCs）即羰基硫（COS）、二甲基硫（DMS）、二硫化碳（CS₂）的浓度分布进行观测,研究了海水中3种主要VSCs的相关性,并估算了3种VSCs的海-气通量.结果表明,东海表层海水COS、DMS和CS₂的浓度平均值分别为（1.0±0.4）、（6.8±6.8）和（0.6±0.4）nmol/L,总体来看东海表层水中3种VSCs呈现出近岸高、远海低的分布趋势.相关性分析表明DMS与Chl-a存在显著相关性,表明浮游植物生物量是影响东海海水中DMS分布的主要因素;同时DMS与CS₂存在着显著的相关性,表明这2种物质的来源有着一定的共性.大气中COS、DMS和CS₂的浓度平均值分别为：（294.7±158.8）、（22.7±18.0）和（108.8±88.1）×10^-12,分布呈现出近岸高,远海低的趋势,主要受到人为活动等陆源输入的影响.此外春季东海COS、DMS和CS₂的海-气通量平均值分别为（4.0±3.4）、（25.8±33.8）和（2.6±2.9）μmol/（m²⋅d）,表明春季东海是大气中3种VSCs重要的源.     

气相色谱法测定二硫化碳和甲硫醚

利用气相色谱(配火焰光度检测器,采用3mxφ2mm玻璃填充柱分离)对CS2和甲硫醚(DMS)两种含硫化合物进行了分离检测。该方法具有较高的灵敏度和良好的线性关系。结果表明:该分析对含硫气体的最小检测浓度在mg/m3级,在柱温为70℃,检测器温度为180℃,气化室温度为150℃,氮气流速为50mL/min时,CS2的回收率为98.66%,变异系数为2.12%;甲硫醚的回收率为98.66%,变异系数为1.56%。     

二甲基硫醚光解及二甲基二硫醚生成速率研究

用低压汞灯照射二甲基硫醚（ＤＭＳ）,在２０ｍ的长光池中用富里叶红外光谱仪测量其光解产物,结果表明二甲基硫醚光解生成二甲基二硫醚（ＤＭＤＳ）和乙烷。测量其不同光照时间的光解产物,结果表明Ｉｎ＾ｃ０／ｃｔ在直解坐标上是一条直线,说明了二甲基二硫醚生成按生一极反应进行,其生成的速率常数为８．７０×１０＾－５ｓ＾－１用低压汞灯照射ＤＭＳ＋Ｈ２Ｏ２体系,富里叶红外光谱检测其产物,在有足够的Ｈ２Ｏ２情况下,生     

2017年9月东海海水和大气中挥发性有机硫化物的浓度分布及其来源

挥发性有机硫化物（volatile organic sulfur compounds，简称VSCs）是硫循环的主要参与者，在全球气候变化和大气化学中发挥重要作用.于2017年9月运用冷阱捕集气相色谱和气-质联用法对东海海水与大气中3种重要的VSCs即羰基硫（COS）、二甲基硫（DMS）、二硫化碳（CS₂）的浓度进行了测定，并计算了它们的海-气通量.研究结果表明，秋季东海表层海水中COS、DMS和CS₂的浓度平均值分别为（0.14±0.08）、（3.58±2.81）和（0.06±0.06）nmol·L^-1.大气中COS、DMS和CS₂的平均浓度分别为（414.9±107.4）×10^-12、（39.7±29.9）×10^-12和（92.9±55.6）×10^-12，COS是大气中含量最丰富的VSCs.相关性分析表明，海水中DMS与CS₂存在相关性，推测两者具有相似的来源途径.大气中COS和CS₂的浓度相关性较为显著，显示大气中CS₂是COS的主要源.此外，海水中COS、DMS和CS₂都呈过饱和状态，海-气通量平均值分别为（0.45±0.58）、（13.15±12.66）和（0.20±0.22）μmol·m^-2·d^-1，表明秋季东海是大气中3种VSCs的源.     

Photochemical production of carbonyl sulfide, carbon disulfide and dimethyl sulfide in a lake water

Photochemical production of carbonyl sulfide(COS),carbon disulfide(CS_2) and dimethyl sulfide(DMS) was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids(cysteine and methionine),and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.     

Carbonyl sulfide and dimethyl sulfide fluxes in an urban lawn and adjacent bare soil in Guangzhou, China

Carbonyl sulfide (COS) and dimethyl sulfide (DMS) fluxes from an urban Cynodon dactylon lawn and adjacent bare soil were measured during April–July 2005 in Guangzhou, China. Both the lawn and bare soil acted as sinks for COS and sources for DMS. The mean fluxes of COS and DMS in the lawn (–19.27 and 18.16 pmol/(m2 sec), respectively) were significantly higher than those in the bare soil (–9.89 and 9.35 pmol/(m2 sec), respectively). Fluxes of COS and DMS in mowed lawn were also higher than those in bare soils. Both COS and DMS fluxes showed diurnal variation with detectable but much lower values in the nighttime than in the daytime. COS fluxes were related significantly to temperature and the optimal temperature for COS uptake was 29°C. While positive linear correlations were found between DMS fluxes and temperature. COS fluxes increased linearly with ambient COS mixing ratios, and had a compensation point of 336 ppt.     

小麦田中有机硫气体的释放

采用密闭箱法对不同施肥条件下小麦田中羰基硫(COS)、二硫化碳(CS₂)和二甲基硫(DMS)的释放情况进行了监测.结果表明,小麦生长过程对COS、CS₂和DMS释放影响显著,小麦对COS有明显吸收作用,DMS和CS₂是麦田中释放的主要含硫气体.COS和CS₂释放速率昼夜变化明显.仅施用有机肥的麦田,硫释放总量高于其它田块.不同施肥条件的田块,硫释放总量范围在-1.40～0.79mg·ml^-2之间.     

Sulfur-containing amino acid methionine as the precursor of volatile organic sulfur compounds in algea-induced black bloom

After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds (VOSCs): methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and dimethyl tetrasulfide (DMTeS). Even in the untreated control without a methionine addition, methionine and its catabolites (VOSCs, mainly DMDS) were found in considerable amounts that were high enough to account for the water’s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine+glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.     

不同有机基质诱发的水体黑臭及主要致臭物(VOSCs)产生机制研究

目前在研究湖泛发生方面还主要停留在视觉(黑色)水平,嗅觉(臭味)因为更加难以判断,有关致臭机制及致臭物质的研究仍停留在检测分析和理论假设方面,缺乏有效的证据证实.采用自制室内模拟装置研究不同有机基质作用下黑臭发生的情况,以确定挥发性有机硫化物(VOSCs)的前驱物并初步研究其降解机制.结果表明,有机物只要达到一定负荷水平(1.0 g.L-1)对水体均有致黑作用,但含硫有机物能使水体在7～13 d就变黑,而不含硫有机物需要13 d以上才能使水体变黑,且含硫有机物能使水体颜色变得更深(最高色度值达410度以上).只有含硫有机物才具有致臭作用,其中二甲基二硫醚(DMDS)、二甲基三硫醚(DMTS)和二甲基四硫醚(DMTeS)是黑臭水体主要的致臭物质.根据蛋氨酸降解产生的VOSCs情况,可确定蛋氨酸为VOSCs的主要前驱物.蛋氨酸以生物降解为主,硫酸还原菌(SRB)是水环境中重要的蛋氨酸降解菌之一,添加SRB使蛋氨酸快速分解为以DMDS、DMTS和DMTeS为主的VOSCs,降解率在第35 d高达95%,并使黑臭暴发的时间从13 d提前至8 d;产甲烷菌对蛋氨酸降解有抑制的趋势,其大量存在可能会抑制小分子硫化物的形成,因此添加甲烷菌抑制剂使黑臭暴发时间提前1 d.非生物降解是蛋氨酸降解的次要途径,仅能使蛋氨酸发生初步降解而水体始终未变黑.     

常压和真空下CS2的光氧化反应

利用原位FTIR、XPS 和GC-MS等技术手段,研究了常温紫外光辐照下常压及真空状态中,CS₂的光氧化反应.结果表明,常压及真空状态下CS₂光氧化反应的产物均为COS、SO₂、CO 和 CO₂,反应均遵循表观一级反应动力学规律,但中间产物COS的浓度变化有较大的差异.常压下COS浓度先迅速增大,然后减少; 真空条件下COS浓度增加到常压下COS浓度的 1/10后基本持平,然后逐渐减小,整个变化趋势缓慢; 2种条件下CS₂的半衰期分别为31.6 s和39.8 s, 中间产物COS降解 98% 所需时间分别为 55 min和22 min.在相同的光照条件下,O₂浓度的增加有助于CS₂光氧化反应的进行.以CS₂光氧化中间产物COS为初始物的光氧化反应主要产物为CO₂和SO₂,后者可以进一步被氧化为SO2-4.适量增加O₂的浓度可以促进COS光氧化反应的进行,但O₂的浓度增加至一定程度后反应速率基本保持恒定.以上结论对揭示CS₂和COS的源和汇以及全球S物质循环具有重要价值.     

Effect of liming on sulfate transformation and sulfur gas emissions in degraded vegetable soil treated by reductive soil disinfestation

Reductive soil disinfestation (RSD), namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils. However, there is little information available about sulfate (SO₄^2 −) transformation and sulfur (S) gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO₄^2 − transformation and S gas emissions, two SO₄^2 −-accumulated vegetable soils (denoted as S1 and S2) were treated by RSD, and RSD plus lime, denoted as RSD₀ and RSD₁, respectively. The results showed that RSD₀ treatment reduced soil SO₄^2 − by 51% and 61% in S1 and S2, respectively. The disappeared SO₄^2 − was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide (H₂S), carbonyl sulfide (COS), and dimethyl sulfide (DMS) were detected, but the total S gas emission accounted for < 0.006% of total S in both soils. Compared to RSD₀, lime addition stimulated the conversion of SO₄^2 − into undissolved form, reduced soil SO₄^2 − by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H₂S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD₁ treatment. The results indicated that RSD was an effective method to remove SO₄^2 −, liming stimulates the conversion of dissolved SO₄^2 − into undissolved form, probably due to the precipitation with calcium.     

生物滴滤塔净化含硫混合废气

利用甲硫醚(DMS)降解菌Alcaligenes sp.SY1和丙硫醇(PT)降解菌Pseudomonas putida.S-1强化生物滴滤塔(BTF)处理DMS和PT的混合废气,研究了其挂膜启动及稳定运行阶段的降解性能,并考察了该系统同时去除H2S的能力.结果表明,BTF在DMS和PT进口浓度均为50 mg·m-3,EBRT为30 s的条件下,运行11 d即可完成挂膜启动,填料上的生物量明显增加,DMS、PT的去除率分别可达到90%和100%.系统稳定运行时,DMS和PT的最大去除负荷分别为8.7 g·(m~3·h)~(-1)和12.4 g·(m~3·h)~(-1),PT的去除效果更佳.DMS和PT混合废气在降解过程中,PT对DMS的降解有较明显的抑制作用,当PT进气浓度大于51 mg·m-3时,DMS的去除效率下降.BTF还能同时有效去除H2S,当混合废气中H2S浓度达到230 mg·m-3时,H2S去除率仍能高达98%,但是115 mg·m-3以上的H2S会对DMS的降解产生不利影响.