Observation of atmospheric nitrous acid with DOAS in Beijing, China

Measurements of nitrous acid （HONO） and nitrogen dioxide （NO2） in Beijing City have been performed by means of a developed differential optical absorption spectroscopy （DOAS） system based on photodiode array （PDA）, during the autumn of 2004. HONO and NO2 were simultaneously identified by their characteristic absorption bands in the spectral region between 337 nm and 372 nm with high sensibility and time resolution. The concentrations of HONO exhibit obviously diurnal variation with a nocturnal maximum and a daytime minimum. The highest HONO value up to 11.8 μg/m^3 was observed during the night of 2/3 September. Possible sources of the observed HONO were discussed. Good correlation to NO2 indicates that NO2 is a main source component. The measurement also shows direct emission of HONO is an imnortant source in strongly polluted urban area.     

不同气源压缩气体泡沫灭石油醚火灾性能比较

采用实验室压缩气体泡沫系统,通过缩尺油盘火试验,分别考察基于不同气源的压缩气体泡沫对于石油醚火灾的灭火性能,分析探讨适用于低沸点的石油醚类燃料火灾扑救的气源类型和供气方案。结果表明,在泡沫溶液供给强度为2.5 L/(min·m2)的条件下,压缩氮气泡沫和压缩空气泡沫均可扑灭石油醚火灾,具有良好的抗烧性能;二者相比,压缩氮气泡沫比压缩空气泡沫的控灭火性能和抗烧性能均有一定提升;对于石油醚类的低沸点易燃液体火灾,建议采用以氮气作为气源的压缩氮气泡沫系统;该研究可为压缩气体泡沫系统在石油化工行业工程应用提供技术支撑。     

液氮泡沫发生器内流动特性研究

低温液氮与泡沫混合液直接接触产生氮气泡沫是一种新型的掺混形式,利用液氮高汽化比的特点,搭建液氮泡沫可视化实验装置,进行氮气-水两相流及液氮泡沫流动特性的研究。结果表明,液氮相变产生大量氮气,其与泡沫液混合产生泡沫,温度有所回升,最终趋于泡沫混合液温度;管路沿程压降较小;液氮射流破碎及流动过程可分为6个区域:低温液氮区、向上循环翻滚区、滞留区、泡沫与泡沫混合液混合区、致密泡沫区、泡沫混合液区。流体向下游流动过程中持续发泡;为防止管路结冰,需合理控制泡沫混合液与液氮流量。     

呼吸效应对矿井封闭火区氧浓度的影响分析

为避免因火区封闭导致重大安全事故发生,通过采集某矿井1 d内3个不同监测点的大气压力变化情况,建立大气压力波动模型并分析计算,同时建立火区内外压差100,750 Pa情形下的氧浓度模型进而获得火区内侧氧气浓度因呼吸效应,在不同压差、体积大小火区、风阻、瓦斯涌出量、封闭时刻等多因素耦合影响下随时间的变化规律,以评估火区危险性。研究结果表明:井下大气随地面大气周期波动,封闭火区内、外侧之间的气压差因外界大气波动呈现16 h的余弦波动和8 h的线性波动周期变化;密闭质量好的火区具有更好地抗干扰性,内侧氧浓度的降低主要依靠瓦斯稀释;密闭质量差的火区,内侧氧浓度易受到火区涌出瓦斯、外界涌入大气双重影响;火区氧浓度在2%~12%之间波动,以至火区存在发生瓦斯爆炸的可能性;火区内外压差较大时,氧浓度波动变化幅度更大,危险作用持续时间更长。结合火区氧浓度波动模型,可有效地对矿井火区采取安全的防范措施,避免瓦斯爆炸事故发生。     

Using Ion-Exchange Resins to Study Soil Response to Experimental Watershed Acidification

Ion-exchange resins (IER) offer alternative approaches to measuring ionic movement in soils that may have advantages over traditional approaches in some settings, but more information is needed to understand how IER compare with traditional methods of measurement in forested ecosystems. At the Bear Brook Watershed in Maine (BBWM), one of two paired, forested watersheds is treated bi-monthly with S and N (28.8 and 25.2kgha⁻¹yr⁻¹ of S and N, respectively). Both IER and ceramic cup tension lysimeters were used to study soil solution responses after ∼11 years of treatment. Results from both methods showed treatments resulted in the mobilization of base cations and Al, and higher SO₄—S and inorganic N in the treated watershed. Both methods indicated similar differences in results associated with forest type (hardwoods versus softwoods), a result of differences in litter quality and atmospheric aerosol interception capacity. The correlation between lysimeter and IER data for individual analytes varied greatly. Significant correlations were evident for Na (r=0.75), Al (r=0.65), Mn (r=0.61), Fe (r=0.57), Ca (r=0.49), K (r=0.41) and NO₃—N (r=0.59). No correlation was evident between IER and soil solution data for NH₄—N and Pb. Both IER and soil solution techniques suggested similar interpretations of biogeochemical behavior in the watershed.     

A new approach to Assess Atmospheric Nitrogen Deposition by Way of Standardized Exposition of mosses

A standardized method of moss exposition for assessing variations in nitrogen deposition was tested in the western part of Germany. Six pleurocarpous moss species were transplanted to two sites differing in their deposition rates but being comparable as to their climatic conditions. The mosses were exposed in standardized containers over a period of 12 months; the focus of interest was the effect of N deposition on nitrogen content and on ¹⁵N natural abundance (δ¹⁵N-values). Within the first nine months only trends could be observed. However, after one year all species tested showed significantly higher N concentrations at the highly polluted site. Besides, more negative δ¹⁵N-values possibly reflecting the higher ammonium input were detected at this site. Surprisingly, most of the plants though being kept in plastic containers without a favourable substratum did not show any conspicuous deficiency symptoms. The potential advantages of a standardized moss exposition for N monitoring purposes are discussed. It is concluded that the method presented here can yield significant results in particular if the number of testing sites is increased.     

An Analysis of Secondary Pollutants in Buenos Aires City

Air pollutant concentrations from a monitoring campaign in Buenos Aires City, Argentina, are used to investigate the relationships between ambient levels of ozone (O₃), nitric oxide (NO) and nitrogen dioxide (NO₂) as a function of NO _x (=NO + NO₂). This campaign undertaken by the electricity sector was aimed at elucidating the apportionment of thermal power plants to air quality deterioration. Concentrations of carbon monoxide (CO) and sulphur dioxide (SO₂) were also registered. Photo stationary state (PSS) of the NO, NO₂, O₃ and peroxy radicals species has been analysed. The ‘oxidant’ level concept has been introduced, OX (=O₃ + NO₂), which varies with the level of NO _x . It is shown that this level is made up of NO _x -independent and NO _x -dependent contributions. The former is a regional contribution that equates the background O₃ level, whereas the latter is a local contribution that correlates with the level of primary pollution. Furthermore, the anticorrelation between NO₂ and O₃ levels, which is a characteristic of the atmospheric photo stationary cycle has been verified.The analysis of the concentration of the primary pollutants CO and NO strongly suggests that the vehicle traffic is the principal source of them. Levels of continuous measurements of SO₂ for Buenos Aires City are reported in this work as a complement of previously published results.     

铜的大气腐蚀研究

综述了各种因素对铜大气腐蚀的影响,其中介绍了单一气体SO2、NOx、O3及混合气体协同作用对铜大气腐蚀的影响。在铜腐蚀中,SO2 NO2的协同效应只有在一个相对高的湿度(90%)下才发生。SO2 O3的协同效应要强于SO2 NO2的协同效应,这可以解释为什么铜在富含O3的乡村环境中有高的腐蚀率。重点阐述了硫酸铵微粒的影响,在硫酸铵的临界相对湿度(CRH)时,铜的腐蚀率和机制变化很显著;同时介绍了铜的几种腐蚀产物及其形成机制。简述了研究铜大气腐蚀的常用实验方法和几种表征手段,并展望了铜大气腐蚀的研究趋势。     

The Influence of Chironomus plumosus Larvae on Nutrient Fluxes and Phosphorus Fractions in Aluminum Treated Lake Sediment

One of the methods to diminish the internal phosphorus (P) loading is inactivation of P by aluminum (Al). After addition of Al to lake water an Al(OH)₃ floc is formed, which settles to the bottom and initially form a lid on the sediment surface. The effects of Chironomus plumosus larvae on sediment nutrient fluxes and P binding-sites in the sediment after addition of Al were tested. C. plumosus larvae were added to sediment cores in which sediment–water fluxes of nutrients were measured four times. After one month, the sediment was sectioned with depth and P fractions were measured by sequential chemical extraction. The chironomids created burrows through the Al layer which caused a significantly increased efflux of P from the Al treated sediment, because the P had only limited contact to the added Al. The chironomids also affected the P fractions in the sediment by their bioturbating activity. Thus, they caused increased Al concentrations in the upper part of the Al treated sediment. This created an enhanced contact between Al and P in the upper 7 cm of the sediment and, as a result, an increased binding of P to Al and a lowered porewater P. The DIP efflux is therefore expected to be lowered after the initial phase. Al had no effects on the nitrogen fluxes, but the chironomids enhanced the release, and decreased the release or increased the uptake by the sediments.     

开放源对环境空气质量影响的评估技术与实例

开放源排放的颗粒物已经成为城市环境大气颗粒物的主要来源之一,介绍了其对环境空气质量影响的评估技术,采用开放源的动力学经验公式测算S市粉煤灰场、原煤堆场、土堆、沙石料堆4类开放源不同粒径颗粒物的起动风速及扩散距离,并利用箱模型(A值)和源解析(化学质量平衡法,CMB)模型测算开放源的区域年均起尘量及其对环境空气中颗粒物的贡献值.结果表明:开放源排放的颗粒物易升腾而且影响面积很大;S市区开放源类排放的小于100 μm的颗粒物约22.2×104 t/a,小于10 μm的颗粒物约15.8×104 t/a;开放源对环境空气中TSP的贡献值约370 μg/m3,质量浓度分担率达60%,对PM₁₀的贡献值约263 μg/m3,分担率达64%.