利用沉积色素恢复湖泊古紫外强度研究综述

自从南极臭氧空洞被发现以来,平流层臭氧浓度下降导致到达地表的紫外辐射增强的现象引起了人们的广泛关注,目前这一状况还在不断加剧并将在未来很长一段时间里持续下去。为了更好地理解这种现象在长时间尺度上的意义以及合理预测未来地球表面紫外环境的变化以及生态系统的响应过程,科学家开始尝试恢复历史时期地球表面紫外辐射的变化。Scytonemin是蓝绿藻细胞外鞘上的一种抗UV色素,高UV强度照射能够促使细胞合成更多的这种色素以保护细胞免受紫外辐射的伤害,并且这种色素在湖泊沉积物中能够很好地保存。因此,我们可以通过分析不同时间段蓝绿藻细胞的scytonemin含量来反映历史时期湖泊紫外环境的变化。进一步的研究可以推测造成这种变化的原因以及生态系统对这些过程的响应,为预测未来地表紫外环境的变化及生态系统的响应提供合适的理论和证据。     

纳米TiO2催化臭氧化对松花江水中氨氮的影响

研究了以负载于陶粒、硅胶、沸石表面的纳米TiO₂作为催化剂时,催化臭氧化松花江水过程中氨氮浓度的变化.结果表明,在单独臭氧化过程中,氨氮浓度先升高后下降,反应30 min后的氨氮浓度与初始浓度相近.在以TiO₂/陶粒、TiO₂/硅胶为催化剂的催化臭氧化过程中,氨氮浓度也是先升高后下降,但反应过程中氨氮的平均浓度要高于单独臭氧化过程.以TiO₂/沸石为催化剂时,催化臭氧化过程中氨氮浓度先下降,然后略有升高,继而又下降,30 min时对氨氮的去除率接近80%.单独臭氧化和催化臭氧化过程中,增大臭氧投量,氨氮浓度最大值出现的时间提前,并且反应过程中氨氮浓度平均值降低.增大催化剂TiO₂/陶粒、TiO₂/硅胶的投量,催化臭氧化过程中氨氮浓度平均值升高.增大TiO₂/沸石投量,有利于氨氮的去除,但投量增大到50g以上时,对氨氮的去除效果影响很小.温度从10℃升高到30℃,对TiO₂/陶粒、TiO₂/硅胶催化臭氧化过程中氨氮浓度的变化影响不大.而以TiO₂/沸石为催化剂时,温度升高有利于催化臭氧化过程中氨氮的去除.     

臭氧/混凝预处理工艺降低膜污染的研究

采用臭氧和混凝工艺分别处理黄浦江原水后进行MF膜过滤试验,考察2种预处理工艺对有机物的作用,进而考察其对MF膜过滤特性的影响.结果表明,2种预处理工艺都存在一个使膜污染下降率达到最大的最佳投药量.2种预处理工艺中,混凝降低膜污染的效果要好于臭氧,这主要与2种预处理工艺所去除的有机物性质有关.黄浦江水中有机物相对分子质量主要集中在3×103～5×103范围内,膜化学清洗液的分析表明造成膜污染的有机物相对分子质量主要集中在4.5×103附近,臭氧对相对分子质量在3×103附近的有机物去除效果较好,而混凝主要去除5×103附近的较大相对分子质量的有机物,因而混凝对这部分污染膜物质的去除效果要好于臭氧,从而有效降低了膜污染.     

低温等离子体-催化协同降解挥发性有机废气

低温等离子体-催化协同技术适合于各类挥发性有机物的治理,特别是大气量低浓度的有机废气的处理.高效催化剂的加入可 以显著提高等离子体反应中有机废气的降解效率,减少有害副产物的生成以及提高反应器的能量利用率.从反应器、催化剂以及背景气体等方面探讨了该技术实现产业化需要解决的问题,结合低温等离子体与催化剂的相互作用、等离子体...     

臭氧处理循环冷却水节能减排效益分析

文章基于臭氧(O3)处理法处理循环冷却水因可以同时达到阻垢脱垢、缓蚀、杀菌等多重功能,其在国外已得到广泛应用,同时国内也逐步普及应用的环境下,结合国内外长期的工程实践经验,从节水、节能、减排和公共卫生效益四个方面,详细分析了臭氧处理循环冷却水所带来的巨大经济效益、社会效益和环境效益。     

Carbonyl emissions from heavy-duty diesel vehicle exhaust in China and the contribution to ozone formation potential

Fifteen heavy-duty diesel vehicles were tested on chassis dynamometer by using typical heavy duty driving cycle and fuel economy cycle. The air from the exhaust was sampled by 2,4- dinitrophenyhydrazine cartridge and 23 carbonyl compounds were analyzed by high performance liquid chromatography. The average emission factor of carbonyls was 97.2 mg/km, higher than that of light-duty diesel vehicles and gasoline-powered vehicles. Formaldehyde, acetaldehyde, acetone and propionaidehyde were the species with the highest emission factors. Main influencing factors for carbonyl emissions were vehicle type, average speed and regulated emission standard, and the impact of vehicle loading was not evident in this study. National emission of carbonyls from diesel vehicles exhaust was calculated for China, 2011, based on both vehicle miles traveled and fuel consumption. Carbonyl emission of diesel vehicle was estimated to be 45.8 Gg, and was comparable to gasolinepowered vehicles （58.4 Gg）. The emissions of formaldehyde, acetaldehyde and acetone were 12.6, 6.9, 3.8 Gg, respectively. The ozone formation potential of carbonyls from diesel vehicles exhaust was 537 mg O3/km, higher than 497 mg O3/km of none-methane hydrocarbons emitted from diesel vehicles.     

化学合成类制药行业工艺废气VOCs排放特征与危害评估分析

以浙江台州6家典型化学合成类制药企业为代表,对其排放工艺废气中的18项挥发性有机物(VOCs)特征污染物(如甲苯、甲醛、二氯甲烷等)进行监测和分析,并采用臭氧产生潜力(OFP)和健康风险评价指标对VOCs所产生的环境与健康危害进行初步的评价.结果表明,化学合成类制药企业排放的总VOCs浓度为14.9~308.6 mg·m-3,其产生环境危害的OFP值为3.1~315.1 mg·m-3,主要贡献物质为甲苯、四氢呋喃、乙酸乙酯等6种物质,存在较大的潜在环境危害.另外,健康危害中的非致癌风险指数和总致癌风险指数介于9.48×10-7~4.98×10-4a-1和3.17×10-5~6.33×10-3之间,主要是苯、甲醛和二氯甲烷这3种致癌物.     

Fe-Ce/GAC催化臭氧降解高浓度腐殖酸废水

采用浸渍焙烧法制备了Fe-Ce/GAC催化剂,并用于催化臭氧降解模拟高浓度腐殖酸废水.以废水COD、腐殖酸浓度为考察指标,研究了Fe-Ce/GAC催化剂的前驱体无机铁盐种类、焙烧温度、铁盐浓度、助剂稀土元素种类及浓度、分散剂硝酸钾浓度等不同制备条件对催化臭氧降解腐殖酸的效果.试验表明,在腐殖酸浓度为3.00 g·L~(-1)、pH值约8.0、温度为25℃、臭氧投量为1.24 g·h~(-1),反应40 min后COD、腐殖酸去除率仅为17.1%、43.0%;添加以2.0%硝酸铁、1.5%硝酸铈、1.0%硝酸钾溶液浸渍,经350℃焙烧3 h后制备的Fe-Ce/GAC催化剂,可使COD、腐殖酸去除率分别提高40.3%、31.8%.且Fe-Ce/GAC催化剂具有较好的稳定性,重复使用5次后,COD、腐殖酸去除率仅小幅降低了4.2%、9.1%.SEM图象显示活性炭经改性后,比表面积明显增大,有利于活性物质的负载;EDS分析表明催化剂负载了大量的Fe、Ce等金属物质;XRD图谱显示催化剂含有Fe_2O_3、CeO_2等多种活性物质.Fe-Ce/GAC催化臭氧的机理可解释为:活性成分氧化铁在催化过程中生成的羟基氧化铁会促进羟基自由基的生成,而铈元素在催化过程中不仅会提高催化剂的活性,而且生成的化学吸附氧可促进对有机物的吸附及氧化.     

Types of Ectomycorrhiza of Mature Beech and Spruce at Ozone-Fumigated and Control Forest Plots

In the Kranzberg forest near Freising (Germany) a novel “Free-Air Canopy O₃ Exposure” system has been employed for analysing O₃-induced responses from sub-cellular to ecosystem levels that are relevant for carbon balance and CO₂ demand of 60-year-old beech trees. The below-ground ectomycorrhizal community was studied in two-fold ambient O₃ concentrations (five cores per sampling) and in a control plot with an ambient O₃ concentration (four cores per sampling). Five samplings were taken throughout two vegetation seasons (2003 and 2004). Types of ectomycorrhiza were determined by their morphological, anatomical and molecular characteristics and quantified by counting. The total number of mycorrhizal fine roots was higher at the fumigated plot as compared with the control site. The numbers of ectomycorrhizal types at the fumigated and control plots were 28 and 26, respectively. Cenococcum geophilum was present in all soil cores at all sampling times with a significant increase in abundance under ozone-fumigated trees. Other mycorrhizal types present at higher abundance at the fumigated than at the control plot were identified as Russula densiflora, R. fellea, R. illota, Tuber puberulum, Lactarius sp. 2 and Russula sp. 2. Some mycorrhizal types were present exclusively at the fumigated plot (Fagirhiza fusca, F. setifera, Lactarius acris, Piceirhiza nigra and Russula sp. 1). A possible ecological role for the abundant types of ectomycorrhiza and their putative application in bio-indication is discussed.     

衡阳市区和衡山背景站臭氧浓度变化规律的对比分析

选取衡阳市区和衡山背景站臭氧自动监测数据,分析两地的臭氧污染特征。对空气质量的优良率情况、臭氧作为首要污染物的变化情况、臭氧浓度的日变化特征、典型时段的浓度变化特征、臭氧浓度的月际变化特征和臭氧与PM_(2.5)的关联情况等进行了分析。结果表明,多云及阴雨天气时,衡阳市区的臭氧浓度日变化幅度大于衡山背景站。夏季,衡阳市区和衡山背景站的臭氧浓度的日变化特征规律差异较大,臭氧浓度分布比较分散,前者为典型的单峰形,后者则波动平缓。冬季,日变化幅度不大,但衡阳市区的臭氧浓度明显低于衡山背景站。衡山背景站和衡阳市区的臭氧基本同步变化,但日均值高于衡阳市区。