基于DCCA方法的成都市市区与周边城镇大气污染长程相关性分析

利用2008年1月～2012年12月期间成都市市区与其周边14个城镇的逐日空气污染指数（API）数据,采用去趋势互相关分析法（DCCA分析）研究区域城市间大气污染的相关性及其随时间演变规律。结果表明:成都市区与其周边城镇大气污染的空气污染存在一定程度的相关性,并且在不同的月份,相关性会随之发生变化。这种相关性具有长期持续特征,具体表现为在一定的时间尺度上成都市区与其周边城镇大气污染的相关性随时间的变化并不遵循经典的马尔可夫过程,即不随时间呈现指数快速衰减,而是以幂律形式随时间缓慢衰减。进一步,结合不同月份间区域大气平均流场的分布特征,探讨了DCCA分析结果的科学性。研究结果说明,在特定地理环境和气象条件控制下,成都市及其周边城市之间已经存在明显的相互输送和耦合作用,成都地区大气污染已由局地性污染转变为区域性大气污染。城市间污染物输送的长期相关影响机制极有可能在特定月份加重成都市区的空气污染状况,这在成都市区及其周边城镇的规划建设中必须加以特别重视     

UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯

酞酸酯是环境中普遍存在的有机污染物(内分泌干扰物)之一。利用UV/TiO2光催化降解水体中的邻苯二甲酸二甲酯(DMP),讨论了溶液pH、TiO2投加量及DMP初始浓度等因素对DMP降解的影响。结果表明,DMP为10mg/L左右时,TiO2投加量为0.2～0.5g/L、pH=7是比较理想的降解条件;DMP初始浓度越高,其降解率则越低。研究了Langmuir-Hinshelwood模式下DMP在TiO2表面的吸附与催化活性的关系,发现DMP主要通过吸附在催化剂的表面而非在溶液本体中发生降解。线性回归计算所得光照条件下的吸附常数远大于无光照条件下的吸附常数,可能是由于UV和TiO2体系之间产生协同效应,提高了UV/TiO2体系对DMP的降解效果。另外,初步分析了可能的降解反应机制。     

Speciated Hydrocarbon Emissions from the Combustion of Single Component Fuels. I. Effect of Fuel Structure

Speciated hydrocarbon emissions data have been collected for six single-component fuels run in a laboratory pulse flame combustor (PFC). The six fuels include n-heptane, isooctane (2, 2, 4-trimethylpentane), cyclohexane, 1-hexene, toluene, and methyl-t-butyl ether (MTBE: an oxygenated fuel extender). Combustion of non-aromatic fuels in the PFC (at a fuel/air equivalence ratio of Φ = 1.02) produced low levels of unburned fuel and high yields of methane and olefins (> 75 percent combined) irrespective of the molecular structure of the fuel. In contrast, hydrocarbon emissions from toluene combustion in the PFC were comprised predominantly of unburned fuel (72 percent). With the PFC, low levels of 1, 3-butadiene (0.3-1.8 percent) were observed from all the fuels except MTBE, for which no measurable level (<0.2 percent) was detected; low levels of benzene were observed from isooctane, heptane, and 1-hexene, but significant levels (9 percent) from cyclohexane and toluene. No measurable amount of benzene (< 0.2 percent) was observed in the MTBE exhaust.

For isooctane and toluene the speciated hydrocarbon emissions from a spark-ignited (SI) single-cylinder engine were also determined. HC emissions from the SI engine contained the same species as observed from the PFC, although the relative composition was different. For the non-aromatic fuel isooctane, unburned fuel represented a larger fraction (50 percent) of the HC emissions when run in the engine. HC emissions from toluene combustion in the engine were similar to those from the PFC.     

Pilot-Scale Study of the Effect of Selective Catalytic Reduction Catalyst on Mercury Speciation in Illinois and Powder River Basin Coal Combustion Flue Gases

Abstract

A study was conducted to investigate the effect of selective catalytic reduction (SCR) catalyst on mercury (Hg) speciation in bituminous and subbituminous coal combustion flue gases. Three different Illinois Basin bituminous coals (from high to low sulfur [S] and chlorine [Cl]) and one Powder River Basin (PRB) subbituminous coal with very low S and very low Cl were tested in a pilot-scale combustor equipped with an SCR reactor for controlling nitrogen oxides (NO_x) emissions. The SCR catalyst induced high oxidation of elemental Hg (Hg⁰), decreasing the percentage of Hg⁰ at the outlet of the SCR to values <12% for the three Illinois coal tests. The PRB coal test indicated a low oxidation of Hg⁰ by the SCR catalyst, with the percentage of Hg⁰ decreasing from ～96% at the inlet of the reactor to ～80% at the outlet. The low Cl content of the PRB coal and corresponding low level of available flue gas Cl species were believed to be responsible for low SCR Hg oxidation for this coal type. The test results indicated a strong effect of coal type on the extent of Hg oxidation.     

水源切换条件下模拟管网铁离子释放控制简

用北京市某供水区域铸铁管段搭建2套模拟管网装置,对水源切换条件下管网铁离子释放的控制进行了研究。实验过程中利用地下水为水源,通过调节进入管网的水中氯浓度为1.0~1.1 mg/L,溶解氧浓度为7~8 mg/L,经过40 d运行后,管垢成分主要为α-FeOOH和Fe₃O₄。切换地表水源后,新的管垢组成更有助于铁氧化物中铁的氧化还原重新达到平衡,从而可以有效减少水源切换条件下铁离子的释放,管网出水浊度也得到很好的控制,保持了管网水质稳定性。     

臭氧对饮用水中氯化消毒副产物生成的影响

以北京市某水厂砂滤池出水为实验原水,研究了臭氧曝气时间对实验原水中天然有机物(NOM)性质、结构及氯化消毒副产物生成的影响。通过高效凝胶色谱、三维荧光光谱、红外光谱等检测分析方法对水中NOM进行表征后发现,经臭氧作用后水样DOC浓度升高、亲水性增加、芳香性及重均分子量下降。有机物中羟基、碳碳双键或碳氮双键及其共轭体系、脱质子羧基官能团与氯反应活性较强。综合考虑臭氧作用后NOM性质、结构变化及氯化消毒副产物生成量的改变,选择最佳臭氧接触时间为12 min。     

中国1997-2006年可持续发展动态测度分析

利用生态足迹分析法对中国1997-2006年的生态足迹与生态承载力进行核算,从而定量测度近10年来中国的可持续发展状况,根据结果对生态足迹的供给和需求进行分析并提出相应的建议和对策.结果表明:10年来,中国的生态足迹快速增长,由1997年的1.287 hm2增长到2006年的1.941 hm2,人均生态赤字从1997年的0.596 9hm2增长到2006年的1.267 0 hm2,自然生态系统处于不可持续的发展状态; 在生态足迹的构成中,能源和水域的生态赤字最为严重,远未满足供需平衡;此外,万元GDP占用生态足迹从1997年的2.014 8 hm2降低到2006年的1.209 8hm2,说明中国资源利用效率提高较快,经济增长方式在向良性发展.     

电子废弃物污染现状及改善对策研究

从环境保护的角度和资源再生利用的角度看,电子废弃物的处理处置已经成为我国面临的一项全新挑战。而且,国内电子废弃物的处理处置正向产业化方向稳步推进。本文介绍了我国目前电子废弃物的特点和处理电子废弃物污染的现状,并且结合我国国情相应地提出了我国在电子废弃物处理处置过程中的预防措施和改善对策。     

西南地区石漠化发生、演变时空特征及成因分析

采用GIS技术对我国西南喀斯特地区石漠化数据进行空间叠加分析,研究了石漠化发生及演变分布、岩性、地貌、区域经济等时空特征,并对我国西南喀斯特地区石漠化成因机理作了初步探讨。研究发现,石漠化发生、演变与碳酸盐岩岩性密切相关;其发生及加剧区域主要分布在较适宜人类活动的峰丛洼地、峰林洼地中;石漠化发生和演变程度与农民人均纯收入水平呈反相关。因此,石漠化治理必须根据石漠化发生和演变的区域、岩性和地貌特点、区域经济发展以及石漠化的程度等条件因地制宜地开展。     

Effect of salinity and sediment characteristics on the sorption and desorption of perfluorooctane sulfonate at sediment-water interface

This study investigated the influence of solution salinity, pH and the sediment characteristics on the sorption and desorption of perfluorooctane sulfonate (PFOS). The results showed that the sorption of PFOS onto sediment increased by a factor of 3 as the CaCl₂ concentration increased from 0.005 to 0.5 mol L⁻¹ at pH 7.0, and nearly 6 at pH 8.0. Desorption hysteresis occurred over all salinity. The thermodynamic index of irreversibility (TII) values increased with increasing concentration of CaCl₂. Maximum irreversibility was found in the sorption systems with CaCl₂ in the concentration of 0.5 mol L⁻¹. The results suggested that PFOS can be largely removed from the water with increasing salinity, and get trapped onto sediments irreversibly. These phenomena could be explained by salting-out effect and Ca-bridging effect. Studies also suggested that the content of total organic carbon is the dominant psychochemical properties of sediment controlling the sorption of PFOS.