Eddy flux measurements of methane over the fen “Murnauer Moos”, 11°11′E, 47°39′N,using a fast tunable diode laser spectrometer

Eddy covariance measurements of methane were carried out over the fen “Murnauer Moos” in the south of Germany in order to evaluate the performance of a newly developed eddy covariance measurement system, based on a frequency-modulated tunable diode laser spectrometer as a fast chemical sensor. During a six-day period, an average daytime methane emission of (5.4±1.8) mg CH₄ m⁻² h⁻¹ was measured. We find this value moderate, considering the favorable meteorological and soil conditions for methane emission. Diurnal cycles of the fluxes of methane and carbon dioxide as well as of sensible and latent heat are presented. Results are discussed in terms of relevant micrometeorological quantities, and quality control procedures based on Allan variance and spectral analysis are discussed.     

Methanol measurements in the lower troposphere near Innsbruck (047°16′N; 011°24′E), Austria

Diurnal variations on a time scale of minutes of the mixing ratios of methanol were measured using proton transfer reaction mass spectrometry (PTR-MS) technique during 67 days throughout the time span from November 1996 to July 1998 together with benzene and other volatile organic compounds at the western outskirts of Innsbruck, Austria. Comparison with the course of the mixing ratio of benzene, which served as marker for traffic emissions, as well as the observation of a seasonal variation allowed to distinguish between different sources for methanol release into the troposphere. Strong evidence for methanol removal via deposition on dew-wetted surfaces is obtained from the comparison of meteorological data with methanol mixing ratios. The mean volume mixing ratio of total methanol was 7.5 nmol mol⁻¹. Mixing ratios ranged from 0.03 up to 45 nmol mol⁻¹.     

Simultaneous measurements of ammonia and nitric acid in ambient air at Agra (27°10′N and 78°05′E) (India)

Simultaneous measurements of ammonia and nitric acid in ambient air were conducted at Dayalbagh, Agra using the mist chamber technique. The sampling site is located near a cattle shed. A total of 120 samples were collected during the period July–September and November–February (1997–1998). Sampling was performed during six different times a day. Gas-phase HNO₃ was estimated as NO₃⁻ using ion chromatographic technique while ammonia was determined colorimetrically as NH₄⁺ using indophenol blue method. The mean levels of NH₃ and HNO₃ for the entire data set were 16.3±2.8 and 1.6±1.4 ppbv, respectively. In the monsoon, mean values for NH₃ and HNO₃ averaged to 16.4±3.5 and 0.9±0.7 ppbv while the winter means were 11.8±4.4 and 2.1±1.2 ppbv, respectively. Concentration of both the species (NH₃ and HNO₃) did not show any significant diurnal behaviour in both the seasons. However, concentration of both NH₃ and HNO₃ were lower at dawn than the previous night's value. This has been ascribed to their removal through dew. Concentrations of HNO₃ are observed to increase during the daytime, consistent with its formation by photochemical reactions. Nitric acid and ammonia concentrations show a significant seasonal variation. Levels of HNO₃ are higher in winter but lower in monsoon, while ammonia shows a reverse trend with higher monsoon and lower winter values. Observed trends in nitric acid and ammonia concentration are due to seasonal variation in emission sources, chemistry and meteorology. Gaseous ammonia and nitric acid are in equilibrium with NH₄NO₃ (solid or aqueous) in the atmosphere. The existence of this equilibrium was examined from simultaneous measurements of NH₃ and HNO₃ in the ambient air. It is found that for the monsoon data, measured concentrations are qualitatively below the predicted equilibrium value, while in the winter, concentration product ([NH₃] [HNO₃]) lies consistently above the predicted values. These deviations may be explained due to local sources of both [NH₃] and [HNO₃], presence of coarse nitrate particles and low-temperature and high-humidity conditions.     

The composition of individual aerosol particle in the troposphere and stratosphere over Xianghe (39.45°N, 117.0°E), China

A balloon observation was carried out on 22 August in 1993 from Xianghe Scientific Balloon Base (39.75°N, 117.0°E) near Beijing in China. Individual aerosol particles in the five samples collected in the troposphere and lower stratosphere were analyzed by using a transmission electron microscope equipped with an energy-dispersive X-ray (EDX) analyzer. Types of particles were classified by the quantitative EDX analysis and particle morphology. Following results were obtained by the analyses of aerosol particles in the radius range of 0.1–0.5 μm: (1) Sulfate particles were dominant (80%) in aerosol particles collected between 4 and 6 km altitude. (2) Sulfuric acid particles were present in 74% of particles at ∼8 km altitude, 91% at 11 km, 95% at 17 km and 88% at 21.2 km. (3) “S-rich” particles with K were collected both in the troposphere and lower stratosphere. It was considered that the particles containing K found at ∼5, ∼8 km altitude could originate from burning processes in the continent including the Tibetan plateau and be transported to the middle troposphere. (4) Sulfuric acid particles with Fe were present in 20–30% of sulfuric acid particles in the lower stratosphere. (5) Particles mainly composed of minerals were present in 6, 11% of particles at ∼5, ∼8 km, indicating the vertical transport to the upper troposphere. (6) Mineral particles which contain sulfuric acid and sulfate suggest the formation of sulfuric acid and sulfate on mineral particles by heterogeneous processes in the troposphere. (7) Sea-salt particles with and without minerals were collected in the troposphere and lower stratosphere, suggesting the vertical transport by convective clouds.     

Distribution of seasonal SO2 emissions from fuel combustion and industrial activities in Shanxi province,China, with 1/6°×1/4° longitude/latitude resolution

Spatial distribution of SO₂ emission inventory for 1994 from fuel combustion and industrial activities in Shanxi province, the Peoples’ Republic of China, has been created with 1/6°×1/4° latitude/longitude resolution. Total annual SO₂ emissions in 1994 in the province were estimated to be 669 GgS, of which 180 GgS were emitted in winter, 170 GgS in spring, 156 GgS in summer, and 163 GgS in fall. For the first time this emission inventory includes SO₂ emissions from village and township enterprises. Although SO₂ emissions from major industries were under control, SO₂ emissions from village and township enterprises became the major threat to the environment in the province.     

Partitioning of formaldehyde between air and ice at −35°C to −5°C

The equilibrium partitioning of formaldehyde (HCHO) between air and snow was studied in a series of laboratory experiments conducted at −5°C, −15°C, and −35°C, in order to understand how partitioning of HCHO between air and polar snow varies with temperature, and thus seasonally on the ice sheet. Measured partitioning coefficients were 56, 93, and 245 mol l⁻¹ atm⁻¹ for −5°C, −15°C and −35°C, respectively, showing a similar trend as the values previously estimated from field observations. Estimates of the pseudo-first-order rate coefficient for air–snow exchange for the same three temperatures were 4.1×10⁻⁴, 1.1×10⁻⁴, and 1.1×10⁻⁵ s⁻¹, respectively. This implies a time scale for air–snow equilibration of the order of hours to days for HCHO accumulated at or near the ice–air interface on snow grains. Comparing the current laboratory partitioning coefficients with those estimated from measurements of air and freshly fallen snow in Greenland during summer demonstrates that the snow is supersaturated and should degas HCHO to the surrounding air. During this degassing, polar snow should be a significant source of HCHO to the lower troposphere.     

A straightforward synthesis in aqueous medium of enantiomerically enriched S(-)2,2′-dihydroxy-1,1′-binaphthyl

Chiral, atropisomeric 2,2'-dihydroxy-1,1'-binaphthyl has been extensively used to direct asymmetric processes. Its key role in asymmetric catalysis has spurred efforts to synthesize it in the optically pure form, but the reported synthetic routes have a significant environmental impact. In an aqueous peroxydase-cyclodextrin system the oxidative coupling of 2-naphthol took place very rapidly in almost quantitative yield and resulted in an enantiomeric excess. This one-pot synthesis do not require any organic solvents and oxidising metal cations.     

超声协同TiO2光催化降解4,4′-二溴联苯

以纳米TiO2膜为光催化剂,对4,4′-二溴联苯水溶液进行了超声光催化（US＋UV）、光催化（UV）和超声（US）降解,探讨了初始浓度、超声的声强和频率等对降解4,4′-二溴联苯的影响。结果表明,4,4′-二溴联苯的超声光催化降解存在协同效应,降解率随4,4′-二溴联苯初始浓度的增大而下降,随声强和频率的增大而增大。超声光催化过程符合一级动力学方程,反应数率常数为0.011 min^-1。超声光催化与光催化的降解产物不同。     

超声协同TiO_2光催化降解4,4′-二溴联苯

以纳米TiO2膜为光催化剂,对4,4′-二溴联苯水溶液进行了超声光催化(US+UV)、光催化(UV)和超声(US)降解,探讨了初始浓度、超声的声强和频率等对降解4,4′-二溴联苯的影响。结果表明,4,4′-二溴联苯的超声光催化降解存在协同效应,降解率随4,4′-二溴联苯初始浓度的增大而下降,随声强和频率的增大而增大。超声光催化过程符合一级动力学方程,反应数率常数为0.011 min-1。超声光催化与光催化的降解产物不同。     

′93首届中国国际环境标志产品博览会将在京举办

“环境标志”是一种印在商品或其包装上的图形,用来表明该产品从生产、使用及回收处置的过程中均符合环境保护要求。实行环境标志是人类认识和解决环境问题的一大进步,也是国际贸易中出现的新趋势。为进一步推动我国环保事业的发展,促进我国对外贸易,中国未来研究会和国家环保局将于10月20日     

Basiswissen Umwelttechnik Wasser, Luft, Abfall, L?rm, Umweltrecht Hrsg: Bank, Matthias

Ohne Zusammenfassung     

氢氧化铝胶体对2,2′,4,4′-四溴联苯醚的吸附

溴代阻燃剂多溴联苯醚(polybrominated diphenyl ethers,PBDEs)是一种被广泛使用的阻燃剂,其对神经、甲状腺、肝脏等具有潜在毒性。其中,2,2′,4,4′-四溴联苯醚(BDE-47)作为一种重要单体,在环境介质中被广泛检出。胶体是环境中污染物迁移过程中的重要载体,它对有机污染物在土壤-地下水系统中的迁移有不可忽略的影响。开展典型无机胶体氢氧化铝胶体对BDE-47的吸附动力学和吸附热力学研究,以期为BDE-47在土壤-地下水中的迁移提供理论依据。结果表明:Sips等温吸附方程对该吸附过程拟合效果最佳(R_(adj)~2=0.943 94),计算得出氢氧化铝胶体对BDE-47的饱和吸附量为609.37 mg·g~(-1);吸附动力学实验结果显示,准二级反应动力学方程拟合氢氧化铝胶体对BDE-47吸附反应过程最佳(R_(adj)~20.95),同时该吸附反应速率随BDE-47浓度的升高逐渐减小;Van't Hoff方程拟合表明,吸附热力学参数标准反应焓变△H~0=40.506 kJ·mol~(-1)、标准反应熵变△S~0=0.075 7 kJ·(mol·K)~(-1),标准反应吉布斯自由能△G~0(298 K)=17.98 kJ·mol~(-1)。此外,反应体系的pH和阳离子种类及浓度均会影响氢氧化铝胶体对BDE-47的吸附过程。     

原子吸收光谱法测定土壤中铜,铅,锌,铬 锰

土壤中铜、铅、锌、铬、锰的含量是很低的,一般为痕量级.目前大多采用高灵敏度的火焰原子吸收法测定.由于土壤中含有大量的矿质元素Si、Al、Fe、Ca、Mg、K、Na、Ti等,经化学分解后,大多进入待测试样溶液,试液中这些复杂的基体常常对原子吸收测定产生严重的干扰或基体效应,影响分析结果的准确性.为了消除基体的干扰,采用APDC/MIBK体系萃取法可有效地分离基体,消除干扰,能获得可靠准确的测定结果.尽管上述方法是可行的,但手续繁、时间费,尤其是还要接触到有毒性的有机溶剂,因此分析工作者一般不乐意采用.本文采用与土壤样品基体相匹配的、待测元素含量相接近的标准土壤样品,校准计算实际土壤样品中待测金属元素的分析结果.试验结果表明,本法能获得准确可靠的分析结果.     

理清思路,明确重点,加强环境保护宏观管理

自改革开放以来，浙江省的环境保护工作取得了很大的进展，工业污染得到一定程度的控制，城市环境综合整治效果显著，自然生态环境保护获得较快发展，环境科技和环保产业初具规模，国际合作初见成效，环境管理体系初步建成。但是，浙江省人多地少资源贫乏，环境污染形势仍不容乐观，生态破坏现状仍比较严重。学习贯彻十五大精神，把浙江省的环境保护工作推向21世纪，任重而道远。1理清思路适应新形势江泽民总书记在十五大报告中正确地分析了我国国情，强调在现代化建设中必须实施可持续发展战略，坚持环境保护的基本国策，正确处理经济发展…     

Nest placement of the giant Amazon river turtle, Podocnemis expansa, in the Araguaia River, Goiás State, Brazil

The giant Amazon river turtle (Podocnemis expansa) nests on extensive sand bars on the margins and interior of the channel during the dry season. The high concentration of nests in specific points of certain beaches indicates that the selection of nest placement is not random but is related to some geological aspects, such as bar margin inclination and presence of a high, sandy platform. The presence of access channels to high platform points or ramp morphology are decisive factors in the choice of nesting areas. The eroded and escarped margins of the beaches hinder the Amazon river turtle arriving at the most suitable places for nesting. Through the years, changes in beach morphology can alter nest distribution.     

综合利用钢渣,变废为宝

去年年底在山东济南钢铁厂召开了钢渣综合利用技术经验交流会,会上介绍了来自全国各钢铁企业、设计研究单位、情报部门和高等院校等近四十个单位的五十六名代表,就钢渣的处理及其综合利用进行了技术经验交流。目前已经开发的综合利用途径有:     

Stoffhaushalt von Auen?kosystemen: B?den und Hydrologie, Schadstoffe, BewertungenHrsg: K. Friese, B. Witter, G. Miehlich, M. Rode Verlag: Springer Verlag, Heidelberg, 2000, 434 S., 196 Abb., 79 Tabellen, ISBN 3-540-67068-8, DM 169,-

Buchpr?sentationen

Stoffhaushalt von Auen?kosystemen: B?den und Hydrologie, Schadstoffe, BewertungenHrsg: K. Friese, B. Witter, G. Miehlich, M. Rode Verlag: Springer Verlag, Heidelberg, 2000, 434 S., 196 Abb., 79 Tabellen, ISBN 3-540-67068-8, DM 169,-