煤烟粒子中PAHS光化学降解的动力学

 利用TEFLON薄膜室内光化学烟雾箱研究了光强、湿度和温度对燃煤烟颗粒物上多环芳烃（PAH_s）的光化学降解速率的影响。结果表明，PAH_S光解速率常数随光强、湿度和温度的升高而增大。在冬季低光强和低水蒸汽浓度的条件下，PAH_s降解速率很小，可在大气中停留数日，因而可传输较远距离。在夏季高光强和高水蒸汽浓度条件下，PAH_s在数小时内即全部降解。通过对光强、水蒸汽浓度和温度的实验数据进行多元回归，得到了降解速率常数与各参数的函数式，即降解反应的动力学方程式。     

Photocatalytic degradation of the dye sulforhodamine-B： A comparative study of different light sources

The photocatalytic degradation of dye pollutant sulforhodamine-B （SRB） in aqueous titanium dioxide （TiO2） dispersions was examined under three lighting regimes： UV light （330 nm〈λ〈 380 nm）, sunlight, and visible light （λ〉450 nm）, all investigated at pH=2.5. Total organic carbon （TOC） and chemical oxygen demand （CODer） assays show that the degradation rate of SRB is much higher when irradiated with UV and sunlight compared with visible light. The temporal concentration changes of SRB illustrated a first-order reaction and the rate constant, k, is 0.197 min^-1, 0.152 min^-1, 0.027 min^-1, respectively, under the three lighting conditions. The final mineralized products were amine compounds identified by infrared spectrophotometry. When irradiated with visible light, the photocatalytic degradation rate could be improved by lowering the H2O2 concentration and inhibited by increasing the H2O2 concentration, but results contrary to the above were obtained when UV light was used for irradiation.     

中国能源消费碳排放的空间化与时空动态

近年来全球多地遭遇极端天气,给人类社会的生产生活带来极大影响,共同应对全球气候变化已成为国际共识,在此背景下如何通过科学方法摸清二氧化碳排放情况成为响应国家"双碳"战略的重要工作.通过省级尺度的碳排放统计数据,综合夜间灯光数据和人口数据,将碳排放量分配到栅格尺度,并对中国2000、2005、2010、2015和2018年碳排放的时空格局、演变特征及碳排放与经济增长的关联性进行综合分析.结果表明：①从2000~2018年,中国的CO₂排放总量持续增长,但增长速率呈现放缓的趋势,碳排放年均增长速率由2000~2010年的9.9%下降至2010~2018年的7.4%.从空间分布来看,无碳排放地区主要分布在西北无人区及东北的林区和山区,低碳排放主要分布在广大的中小城镇地区,高碳排放则集中分布于华北、华中、东部沿海以及西部的省会城市及城市群附近;②碳排放在地级市尺度上存在高值聚集或低值聚集现象,且该聚集现象整体趋于稳定,在2005年之后有所加强;低低集聚区主要分布在西部的连片地区和海南岛,且随着经济社会的发展,低低集聚区开始破碎,规模减小;高高集聚区主要分布在京津冀城市群、太原城市群、长江三角洲城市群和珠江三角洲城市群地区且规模在逐步加强巩固;高低、低高集聚区则主要出现在社会经济发展水平差异较大的邻近城市;③中国大部分地区的碳排放量相对稳定,碳排放发生较大变化的地区主要分布在省会城市和重点城市的外围地区,即存在中心城区碳排放无变化,外围区域碳排放变化的圈层结构;④在2000~2018年中国城市发展进程中,整体上遵循一个由"低排放-低收入"转向"高排放-低收入"再转向"高排放-高收入"最终转向"低排放-高收入"的发展规律.从整体来看,中国碳排放的增速在放缓,在实行"双碳"战略的大背景下,各地区由于不同的社会经济发展情况和能源需求情况所面临的碳减排任务与压力也不尽相同,因而应分地区和分行业实施差异化的碳减排政策.     

Synthesis of surface sulfated BiWO with enhanced photocatalytic performance

Sulfated BiWO (SBiWO) was synthesized by an impregnation method to enhance the visible-light-driven photoactivities of BiWO (BiWO). The characterization results verified that sulfate anion mainly anchored on the catalyst surface greatly extended the visible-light-responsive range without destroying the crystal lattice. Moreover, the SBiWO-based photoactivities were evaluated with the removal of Malachite Green (MG) under UV-Vis irradiation emitted from two microwave-powered electrodeless discharge lamps (MPEDL_-2) and under visible light (λ > 420 nm). The results demonstrated that the kinetic constant was increased 2.25 times, varying from 0.1478 (BiWO) to 0.3328 min^-1 (SBiWO-1). Similar results were also obtained for the visible light-driven reaction. Furthermore, radical scavengers such as t-butanol restricted the visible-light induced degradation of MG over BiWO and SBiWO-1. This indicated that the sulfating process increased the generation of reactive oxygen species, which was further verified by molecular probe with salicylic acid. Thus, more blue-shifting at λ = 618 nm was observed over SBiWO. On the basis of the above results, the photocatalytic mechanism over the sulfated catalyst was also discussed.     

Evaluation of the International Vehicle Emission （IVE） model with on-road remote sensing measurements

Intemational Vehicle Emissions （IVE） model funded by U.S. Environmental Protection Agency （USEPA） is designed to estimate emissions from motor vehicles in developing countries. In this study, the IVE model was evaluated by utilizing a dataset available from the remote sensing measurements on a large number of vehicles at five different sites in Hangzhou, China, in 2004 and 2005. Average fuel-based emission factors derived from the remote sensing measurements were compared with corresponding emission factors derived from IVE calculations for urban, hot stabilized condition. The results show a good agreement between the two methods for gasoline passenger cars＇ HC emission for all 1VE subsectors and technology classes. In the case of CO emissions, the modeled results were reasonably good, although systematically underestimate the emissions by almost 12%-50% for different technology classes. However, the model totally overestimated NOx emissions. The IVE NOx emission factors were 1.5-3.5 times of the remote sensing measured ones. The IVE model was also evaluated for light duty gasoline truck, heavy duty gasoline vehicles and motor cycles. A notable result was observed that the decrease in emissions from technology class State II to State I were overestimated by the IVE model compared to remote sensing measurements for all the three pollutants. Finally, in order to improve emission estimation, the adjusted base emission factors from local studies are strongly recommended to be used in the IVE model.     

紫外辐射对高岭土混凝过程的影响机制

高岭土普遍存在于水源水体中,对水处理过程以及污染物的迁移转化有着重要的影响.本文以聚合氯化铝作为混凝剂,通过烧杯实验系统考察了紫外辐射对高岭土混凝过程的影响规律.结果表明,在中性和偏酸性环境下,紫外辐射对高岭土悬浊液的混凝过程具有一定的促进作用.当溶液pH、混凝剂投量以及辐射时间分别为7.0、30 mg·L~(-1)和2.0 h时,紫外辐射后高岭土在混凝出水中的去除率可由原来的81.05%增至93.90%.这可能与光辐射后高岭土结构中的—OH伸缩振动吸收强度降低,Si—O伸缩振动吸收峰和Si—O弯曲振动吸收峰有所增强有关,使得高岭土表面的活性位点(—OH)数量下降;宏观上表现为微粒表面所带负电性下降,有利于在混凝过程中脱稳沉降.然而,在碱性条件下,其沉降性能却略低于未经紫外辐射处理的水样.     

不同林木种群对紫茎泽兰营养生长和生殖生长的影响

外来植物紫茎泽兰（Eupatorlum adenophorum）入侵我国西南地区并造成了严重的生态灾难,通过研究不同林木种群下紫茎泽兰的生长特性和发生规律,有助于从生态学角度为紫茎泽兰的综合防控提供事实依据。我们分别于2009、2011和2012年在西昌袁家山上开展了不同人工林木群落下紫茎泽兰营养生长和生殖生长特性的调查。调查研究的结果表明,阔叶林（青冈林）、阔叶针叶混交林（油茶柏树混交林）和阔叶混交林（油茶青冈混交林）下光照强度显著低于两种针叶林（落叶松林和柏树林）和空旷地,光照强度较空旷地减少率均在90％以上。空旷地紫茎泽兰的发生密度可达到111-218株·m-2,两种针叶林（落叶松林和柏树林）对紫茎泽兰的发生表现出一定的抑制作用,抑制率能达到46．2％～77．1％。油茶柏树混交林和青冈林下紫茎泽兰只有零星发生,对紫茎泽兰发生抑制率3年均在90％以上,而在油茶青冈混交林下未发现有紫茎泽兰发生。空旷地紫茎泽兰株高和分枝数均要显著高于其他人工林木群落,单株株高可达160．5～180．3cm,单株分枝数达到14．9～17．4,其中两种针叶林下紫茎泽兰的株高和分枝数要显著高于两种混交林和青冈林,株高达到59．5～113．4cm,单株分枝数为6．4～14．8。此外种植人工林木也显著抑制了紫茎泽兰的开花结实,空旷地紫茎泽兰单株种子量能达到8314～15410粒,两种针叶林（落叶松林和柏树林）下紫茎泽兰单株种子发生量为1330-4666-3粒,而两种混交林和青冈林下紫茎泽兰只有零星开花或不开花结实。相关性分析结果显示,光照强度的大小与紫茎泽兰的发生密度、株高、分枝数、单株花苞数、单株种子数都呈显著正相关,即光照强度显著影响着紫茎泽兰的发生密度、生长以及开花结实。阔叶林下光照强度的减弱是导致紫茎泽兰发生量减少原因之一。开展植树造林,采用种植青冈林、油茶青冈、油茶柏树混交林等阔叶混栽的方式对紫茎泽兰的发生不仅能起到显著的生态控制效果,而且能绿化荒山,给农民带来经济效益。     

Surface solar ultraviolet radiation: A theoretical approach of the SUVR reaching the ground in Athens, Greece

Daily total ozone observations made during 1985–1993 by both the Total Ozone Mapping Spectrometer (TOMS) flown on the Satellite Nimbus-7 and the Dobson Spectrophotometer have been used in order to investigate the fluctuations of the daily broad-band and spectral solar ultraviolet radiation reaching the ground. This investigation has been performed by employing a recently developed parametric algorithm for the estimation of the spectral and broad-band solar ultraviolet radiation which takes the total ozone variations into consideration. Total ozone reductions during the summertime from 1985 to 1993 over Athens, Greece (37.6° N, 23.4° E), cause an increase in the ultraviolet irradiance which reaches the ground of 0.54 %, 0.98 %, 2.60 % and 0.79 % per decade for the months of July at 300 nm, 312 nm, 320 nm and UVB (280-320 nm), respectively.     

氮掺杂TiO_2可见光光催化剂的制备及性能

以尿素和钛酸丁酯为原料,通过溶胶-凝胶法低温下制备了高可见光催化活性的氮掺杂TiO2（NDT）光催化剂,采用XRD、TEM、BET和UV-Vis DRS等测试手段对其进行了表征,并在自制光催化反应器中降解甲基橙评价了样品的光催化活性。结果表明,当氮与钛的摩尔比为0.5∶1时,350℃焙烧的样品（NDT350）具有最佳的可见光光谱吸收和光催化活性,该催化剂为锐钛矿晶相,平均粒径为21 nm,比表面积为89.13 m2/g。可见光辐照下,NDT350降解甲基橙的表观反应速率常数为1.381×10-2min-1,是商业P25催化剂的16.85倍。NDT350优良的可见光催化活性与其大的比表面积和强烈的可见光光谱吸收有关。     

纳米TiO2改性可见光催化降解有机物研究进展

光催化降解水中有机污染物是一项颇有发展前途的废水处理技术.目前主要的研究工作由紫外光逐步向可见光催化方向发展,使这项技术向实用性又迈进了一步.系统介绍了纳米TiO2的光催化降解有机污染物的原理,光催化处理水的现状,并从离子掺杂、表面光敏化和分子筛负载几个方面综述了可见光化的研究现状和发展方向.