环境因素对土壤含硫气体释放的影响

研究了温度、光照条件两种环境因素对添加不同硫源（胱氨酸、硫酸二乙酯和硫酸钠）土壤含硫气体释放的影响。结果表明,随着培养温度升高,含硫气体释放量增大,而且释放气体种类增多。COS在各种不同处理的土样中均有释放。除添加硫酸二乙酯的土样外,其它各种土样COS释放量与培养温度有很好的相关性,相关系数在0．95以上。添加胱氨酸的土样,含硫气体释放明显高于其它土样,光照条件变化对各种含硫气体释放量影响不大,但在弱光和无光照条件下检出的含硫气体种类较多。     

稻田中有机硫气体释放的研究

分析测定了水稻生长期内含硫气体的释放通量 .分析表明 ,水稻的生理活动对含硫气体的释放有显著的影响 ,水稻主要释放二硫化碳 (CS2 )和二甲基硫 (DMS)气体 .而对羰基硫 (COS)有一定的吸收作用 .水稻田中总硫平均释放强度约为 5 0mg·m- 2 ,施肥对稻田硫的释放有影响     

陆地生态系统含硫气体释放研究进展

由自然生态系统释放的含硫气体在全球硫循环中起着重要作用。陆地生态系统主要的自然硫释放源有湿地、土壤、植被、内陆水体和火山等，由自然源释放的含硫气体主要产生于有机硫化物的降解和硫酸盐的还原，同时受温度、光照等环境因素的影响。文章主要综述了对人类有影响的几种含硫气体(DMS、H2S、COS、CH3SH、CS2和DMDS等)从各种自然源释放的情况，同时简要介绍了环境因素如温度、光照、土壤状况、氧化还原条件等对自然源释放含硫气体的影响，最后结合中国的研究现状，指出今后应开展和加强陆地生态系统含硫气体释放通量监测、释放机理及在大气中的转化等方面的研究，以及在此基础上建立含硫气体释放模型。     

水稻土中半胱氨酸分解产生含硫气体的研究^1）

在室内培养条件下,测定了水稻土中含硫气体的释放,结果表明,该土壤中有硫化氢（H2S）,羧基硫（COS）,二甲基硫（DMS）三种气体释放,当土壤中加入半胱氨酸后,COS和H2S气体的浓度有了明显增加,并有CS2和CH3SH测出,而DMS的浓度变化不大,这些结果表明法胱氨酸的分解可能是COS,H2S,CS2和CH3SH的产生源之一,在好氧（正常大气）条件下,H2S,COS,CS2和CH3SH的释放量低于氧（氮气氛围）条件下的释放量,DMS则高于厌氧条件下,这表明水稻土中半胱氨酸分解产生H2S,COS,CS2和CH3SH需较强的还原条件,产生这四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,在光照条件下,各含硫气体的释放量普遍高于无光照条件下的释放量,释放含硫气体的大多数微生物适宜的含水率为50％且对土壤的pH值有一定要求。     

水稻土中半胱氨酸分解产生含硫气体的研究

在室内培养条件下,测定了水稻土中含硫气体的释放．结果表明,该土壤中有硫化氢(Ｈ２Ｓ),羰基硫(ＣＯＳ),二甲基硫(ＤＭＳ)三种气体释放．当土壤中加入半胱氨酸后,ＣＯＳ和Ｈ２Ｓ气体的浓度有了明显增加,并有ＣＳ２和ＣＨ３ＳＨ测出,而ＤＭＳ的浓度变化不大．这些结果表明半胱氨酸的分解可能是 ＣＯＳ,Ｈ２Ｓ,ＣＳ２和 ＣＨ３ＳＨ的产生源之一．在好氧(正常大气)条件下,Ｈ２Ｓ,ＣＯＳ,ＣＳ２和ＣＨ３ＳＨ的释放量低于厌氧(氮气氛围)条件下的释放量,ＤＭＳ则高于厌氧条件下．这表明水稻土中半胱氨酸分解产生 Ｈ２Ｓ,ＣＯＳ,ＣＳ２和 ＣＨ３ＳＨ需较强的还原条件,产生这四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．在光照条件下,各含硫气体的释放量普遍高于无光照条件下的释放量．释放含硫气体的大多数微生物适宜的含水率为５０%且对土壤的ｐＨ值有一定要求．     

淮北煤田煤中有机硫的测定与分析

以淮北煤田16 个煤样品为研究对象,对每个样品均进行了元素分析,并进行了索氏抽提实验,采用气相色谱-质谱仪对提取液进行测试分析.结果表明,淮北煤田4煤层和5煤层是以低硫煤为主的烟煤,煤中的有机硫主要为含硫多环芳烃(PASHs),其中又以二苯并噻吩及其甲基取代物和苯并萘并噻吩及其甲基,二甲基取代物为主.通过比较相对含量,发现5煤层的PASHs普遍比4煤层高,且PASHs的含量与O/C值成反相关,与煤的变质程度关系密切,煤化程度愈高,煤组成的芳构化程度也愈高,PASHs含量亦愈高.同时还发现当煤中硫含量在0.5%左右时,煤中PASHs含量达最高.     

煤的化学脱硫研究

以我国的三种高硫煤－山东兖州、四川南楠、东林煤为试验煤样，考察了Ｆｅ２（ＳＯ４）３溶液和ＮａＯＨ溶液加热处理的脱硫作用，以及热解时煤中有机硫的变化。试验发现，用２ｍｏｌ／ｌＦｅ２（ＳＯ４）３在反应温度１００℃，反应时间４ｈ下，可脱除近８０％的硫铁矿硫；经６％ＮａＯＨ溶液处理后再用５％ＨＣｌ浸煮，即可有效脱除煤中矿物质，也能明显脱硫；在煤热解时，煤中有机硫大部分滞留于煤焦中，被脱除的硫主要以Ｈ２Ｓ形     

矿物质对煤热解气化过程中NH3形成的影响

以酸洗脱灰煤、原煤及添加含铁化合物的煤样作为研究对象,考察了煤中的矿物质和添加物铁对平朔气煤热解、CO2气化和水蒸气气化过程中形成的NOx前驱物NH3释放的影响．结果表明：煤中的矿物质和添加物铁在煤的热解和气化过程中,对NH3的释放均有明显的作用;煤中矿物质的脱除和添加剂的存在均可以减少NH3的释放,但其作用机理并不同．     

生物除硫理论与技术研究进展

现今含硫废水、废气的处理并没有得到应有的重视,使得技术发展缓慢。以往通常采用物化方法,这种处理方式不仅投资量大,而且对含硫有害物质的去除并不彻底,而生物方法与物化方法相比,在投资和环保效益方面都有相当积极的作用。文章从硫的生物循环入手,分别介绍了生物除硫的机理和影响因素;描述了下水道中的生物硫循环,提出抑制其中H2S气体释放的经验模型及具体措施。在对厌氧消化系统中硫酸盐还原菌的研究中发现:ρ(COD)/ρ(SO42-)比、碳源、pH值等各影响因素相互作用,共同决定厌氧消化系统中硫酸盐还原菌、产甲烷菌和产酸菌三者之间的抑制及共生关系;无论三者之间的关系如何变化,只要底物中含有一定量的硫酸根,它们必然共同存在于厌氧系统中,并产生硫化氢气体,造成污染。在反硫化细菌的研究中得出:当污水中同时含有硫化物和硝酸根,缺氧条件下,必然产生反硝化除硫的生物代谢过程。利用这一过程,不但能够在无需碳源的条件下有效去除硝酸根,节约的碳源可以用于消化产能;而且能够减少游离硫化氢的排放,或直接以含硫化氢的废气作为硫源。而抑制下水道中硫化氢气体释放的主要手段包括:降低水的紊流程度,增加入流污水的碱度,向下水道内充氧,改善通风环境。文章最后结合理论,介绍了部分用于含硫污水、尾气的生物除硫工艺,并提出了日后的研究方向。     

矿物质与矿物离子对煤中硒释放行为的影响

利用固定床热解反应装置研究了煤中不同类矿物质及不同矿物离子(Ca2+、Si4+、Al3+、Mg2+)对黑代沟烟煤、霍林河褐煤及各自的酸抽提(HCl、HF、HNO3脱矿物质)样品中硒释放行为的影响.研究发现,热解过程中,碳酸盐、硫酸盐、单硫化物、磷酸盐与氧化物(HCl脱除的矿物质)抑制了两种煤中硒的释放,且对黑代沟烟煤中硒释放的抑制作用较强;铝硅酸盐类(HF脱除的矿物质)对两种煤中硒释放的抑制作用均较强;而煤中黄铁矿类(HNO3进一步脱除的矿物质)在其分解转化过程中会形成更加稳定的新物质而抑制硒的释放.担载的Ca2+、Si4+、Al3+、Mg2+对黑代沟与霍林河煤的HCl/HF-抽提样品中硒的释放均有抑制作用,但作用的强弱顺序不同.对黑代沟煤为:Ca2+>Si4+>Al3+>Mg2+,而对霍林河煤为:Ca2+>Al3+>Si4+>Mg2+.     

二种高硫煤中硫氮化学形态的研究

利用ＸＰＳ技术研究了贵定煤和西班牙Ｍｅｑｕｉｅｎｚａ煤中硫和氮化学形态的分布，并结合硫Ｋ－边ＸＡＮＥＳ和Ｍｏｓｓｂａｕｅｒ谱着重考察贵定煤中硫化学形态。结果表明，贵定煤中含硫化合物主要以噻吩形态存在，其次为有机硫化物；而Ｍｅｑｕｉｅｎｚａ煤中以有机硫化物含量最大，噻吩硫次之，有关含氮化合物，Ｍｅｑｕｉｅｎｚａ煤以吡咯和吡啶氮为主，但在贵定煤中观察到较大浓度的氧化氮化合物。     

酸性矿山废水治理过程中产生二次污染的研究

在易氧化的硫化物矿物尾矿上叠加生活污水或乙酰丙酮等阻断尾矿向酸性矿山废水转移过程中,引发了硫化物矿物氧化产生的还原性硫与有机污水中一些水溶性有机物以及乙酰丙酮的作用,生成以CS_2为主的新的二次污染物.     

Lead in Chinese coals: distribution,modes of occurrence,and environmental effects

Lead (Pb) has gained much attention since the 1970s because of its potential and cumulative toxicity. As one of the most hazardous elements in coals, Pb can be released into the environment during coal mining, processing, and utilization. This study presents a synthesis on the abundance, distribution, modes of occurrence, and environmental impacts of Pb in Chinese coals. Using the expected coal reserves as the weighting factor and based on the previously published Pb content in 4,304 coal samples (including results obtained in our laboratory) from main coalfields or coal mines in China, the weighted mean Pb content in Chinese coals is 13.0 μg/g, which is higher than that of the American coals (11 μg/g) and average world coals (7.8 μg/g). With respect to regional distribution of Pb in Chinese coals, Pb content can be arbitrarily divided into three groups (<20, 20–40, >40 μg/g). Following this classification, coals from Tibet have the highest average Pb content (128.94 μg/g). The abundance of Pb in coals varies with coal-forming periods and coal ranks, with the late Triassic and higher rank coals having the highest Pb content, which could be ascribed to regional geochemical differences and later geological evolution as well as magma hydrothermal activities. The enrichment of Pb in coals is influenced by several geological factors, including coal-forming plants, source rocks, hydrothermal fluid, and depositional environment. Pb, dominantly associates with sulfide minerals, especially galena in coals. During coal combustion or pyrolysis, Pb is partly emitted into the atmosphere and partly partitioned to solid residues. Accumulation of Pb from coal utilization in human body could lead to a range of health problems and increase the risk of cancer.     

Lead distribution in Permo-Carboniferous coal from the North China Plate,China

The content and distribution of the lead in coal, gangue and the sulfur ball and the pyritic gangue of the Permo-Carboniferous in the North China Plate have been systematically studied (nearly 300 samples) in this paper. The Permo-Carboniferous coals in the North China Plate account for nearly 44.45 of total Chinese coal resources, and most of the steam coals in China come from the Permo-Carboniferous coals in the North China Plate. The result shows that lead content in the coal varied from 1.45 to 63.60 mg kg^–1, averaging 23.95 mg kg^–1; the lead content of the sulfur ball and the pyritic gangue in the coal seam ranges from 70.26–1060 mg kg^–1, with an average of 271.28 mg kg^–1; the lead content of the gangue is from 29.5 to 77.81 mg kg^–1, averaging at 40.77 mg kg^–1. The lead in the coal seam is mainly concentrated in the pyrite, such as sulfur ball, pyritic gangue or pyrite, and is the least concentrated in the organic of coal. The content of the lead has a direct ratio with the ash and the pyretic sulfur. Coal washing can reduce the content of the pyretic sulfur and the lead.     

甲草胺热裂解气相色谱-质谱分析

甲草胺是一种广泛用于农作物上的酰胺类除草剂.本文利用裂解气相色谱与质谱联用(Py-GC-MS)研究了甲草胺在热裂解温度200℃、400℃、600℃、800℃下的降解产物和热降解机理.实验结果表明,共有60种裂解产物被分离鉴定,随着温度的升高甲草胺显著分解,当裂解温度超过600℃时,大量的芳烃类、喹啉类、吲哚类化合物在高温裂解中产生,温度越高他们的相对含量也越高.基于对裂解产物的定性和它们含量的变化提出了甲草胺的热降解机理.     

Mechanism insight into the formation of H2S from thiophene pyrolysis: A theoretical study

• Possible formation pathways of H₂S were revealed in thiophene pyrolysis. • The influence of hydrogen radicals on thiophene pyrolysis was examined. • Thiophene decomposition starts with hydrogen transfer between adjacent C atoms. • The presence of hydrogen radicals significantly promotes the formation of H₂S. Pyrolysis is an efficient and economical method for the utilization of waste rubber, but the high sulfur content limits its industrial application. Currently, the migration and transformation of the element S during pyrolysis of waste rubber is far from well known. In this work, a density functional theory (DFT) method was employed to explore the possible formation pathways of H₂S and its precursors (radicals HS· and S·) during the pyrolysis of thiophene, which is an important primary pyrolytic product of rubber. In particular, the influence of reactive hydrogen radicals was carefully investigated in the thiophene pyrolysis process. The calculation results indicate that the decomposition of thiophene tends to be initiated by hydrogen transfer between adjacent carbon atoms, which needs to overcome an energy barrier of 312.4 kJ/mol. The optimal pathway to generate H₂S in thiophene pyrolysis involves initial H migration and S-C bond cleavage, with an overall energy barrier of 525.8 kJ/mol. In addition, a thiol intermediate that bears unsaturated C-C bonds is essential for thiophene pyrolysis to generate H₂S, which exists in multiple critical reaction pathways. Moreover, the presence of hydrogen radicals significantly changes the decomposition patterns and reduces the energy barriers for thiophene decomposition, thus promoting the formation of H₂S. The current work on H₂S formation from thiophene can provide some theoretical support to explore clean utilization technologies for waste rubber.     

Arsenic content and distribution pattern in Chinese coals

About 500 samples of coal, pyritic coal balls, pyritic gangue and coal seam gangue were collected from different coal basins and geologic periods of coal formation to determine the arsenic (As) content and distribution pattern in China. The Permian-Carboniferous and Jurassic coals in the North China Plate and Northwest China account for nearly 85% of total Chinese coal reserves and data showed that As content ranged from 0.1 to 94?mg?kg^?1, with the majority between 1 and 14.9?mg?kg^?1. The As content of some Late Permian coals in Southwest Guizhou Province and stone coal in the South Qinling Mountain area were exceedingly high (30–534?mg?kg^?1), but the majority of coal in the Southwest Guizhou Province contained low to medium amounts. Only the coals, which are situated in or near igneous rocks and are not considered a part of Chinese coal reserves, possessed unusually high As content (>30?mg?kg^?1). Arsenic was also concentrated in pyritic coal balls and the pyritic gangue of the coal seam with values ranging from 21.5 to 142.46?mg?kg^?1 and an average of 69?mg?kg^?1 in Shaanxi and 78?mg?kg^?1 in Shandong. Arsenic contents in coal gangue in the Northwest and North China Plate is about 0.2–15?mg?kg^?1, a little lower than coals in the same seam. Washing gangue (waste from coal washing) generally contained more As than coal, because the washed gangue has more pyrite than the natural gangue (black shale). Washing coal reduced the content of the pyritic sulfur, heavy metals and As. Based on amounts of coal used with different As content in Chinese coal reserves, the average As content of Chinese coals is about 4.5?mg?kg^?1.