Review of heterogeneous photochemical reactions of NOy on aerosol－A possible daytime source of nitrous acid (HONO) in the atmosphere

As an important precursor of hydroxyl radical, nitrous acid (HONO) plays a key role in the chemistry of the lower atmosphere. Recent atmospheric measurements and model calculations show strong enhancement for HONO formation during daytime, while they are inconsistent with the known sources in the atmosphere, suggesting that current models are lacking important sources for HONO. In this article, heterogeneous photochemical reactions of nitric acid/nitrate anion and nitrogen oxide on various aerosols were reviewed and their potential contribution to HONO formation was also discussed. It is demonstrated that HONO can be formed by photochemical reaction on surfaces with deposited HNO3 , by photocatalytic reaction of NO2 on TiO2 or TiO2 -containing materials, and by photochemical reaction of NO2 on soot, humic acids or other photosensitized organic surfaces. Although significant uncertainties still exist in the exact mechanisms and the yield of HONO, these additional sources might explain daytime observations in the atmosphere.     

成都市部分中小型污水处理厂运行情况调查

本文以成都市部分中小型污水处理厂运行情况调查资料为基础,对10个污水处理项目的处理效果、投资、土地占用、运行费用等情况进行了分析,提出了一些带普遍性的问题。     

苯并(a)芘和芘暴露对梭鱼肝脏超氧化物歧化酶活性的影响

在实验生态条件下，浓度范围0．1－0．5ug/L的苯并（a)芘和芘的短期暴露（7d),50ug/L浓度组造成梭鱼肝脏SOD活性先抑制后诱导的效应，5ug/L浓度在7d的暴露中，SOD活性未出现诱导而是抑制。同样在50ug/L浓度下，苯并（a)芘暴露4d后SOD活性出现诱导，而芘在暴露7d后才出现诱导，这间接反映了苯并（a)芘和芘的毒性大小。这些结果说明梭鱼肝脏SOD活性与苯并（a)芘和芘暴露有一定的相关性，可以作为海洋环境多环芳烃污染监测的一种生物标志物。     

针铁矿改性生物炭对砷吸附性能

为了提高生物炭(BC)对砷的吸附能力,本研究选取小麦秸秆作为原料,采用共沉淀方法制备了针铁矿(Goethite)改性生物炭材料(Goethite@BC).比较了BC、Goethite和Goethite@BC对As(Ⅲ)的吸附特性,同时使用SEM-EDS、BET、FT-IR、XRD和XPS等技术对改性吸附剂的理化性质和吸附机制进行表征.结果表明,扫描电子显微镜分析显示有纳米级针铁矿附着在生物炭表面,可有效提高生物炭的比表面积和总孔容; 3种吸附剂对As(Ⅲ)的吸附符合伪二级动力学模型和Langmuir等温吸附模型,Goethite@BC对As(Ⅲ)的最大吸附量为65. 20 mg·g~(-1),与BC相比吸附量提高了62. 10倍. Goethite@BC吸附机制包括非特异性吸附(静电引力)和特异性吸附(配位、络合、离子交换等),纳米针铁矿颗粒在Goethite@BC表面对污染物的吸附起到重要作用. Goethite@BC在污染物修复领域具有很好地应用前景.     

First-trimester diagnosis of hydrolethalus syndrome in a Chinese family

We report a case resembling hydrolethalus syndrome in a Chinese family. Fetal polydactyly, syndactyly, encephalocele and cardiac malformation were detected on ultrasound examination at 12 weeks' gestation. Termination of pregnancy was performed, and postmortem examination confirmed the findings. This is the first report of a first-trimester prenatal diagnosis of hydrolethalus syndrome in the Chinese population. Copyright © 2004 John Wiley & Sons, Ltd.     

选择试验模型法在耕地资源保护中的应用——以浙江省温岭市为例

选择试验模型法是目前国际上用于评估具有公共物品特性的自然资源和环境物品经济价值的一种相对较新的方法。论文以浙江省温岭市耕地资源保护为例,探讨选择试验模型法在耕地资源保护经济价值评估实践的可行性。在专家咨询和小组讨论的基础上,确定耕地景观、田间设施、土壤肥力和耕地保护费为温岭市耕地资源保护的4个属性。在对温岭市246名居民进行随机抽样调查的基础上,分析了温岭市耕地资源保护不同属性的价值以及耕地资源保护不同替代方案的相对价值。结果表明,对于温岭市全体居民来说,今后耕地资源保护的实施应该重点改善田间设施和提高土壤肥力,而耕地景观的改善也同样可以增加温岭市居民的福利水平。     

Cr~(3+)胁迫对小球藻生理生化特性的影响

水体重金属污染较难处理,且会对水生物造成严重的影响。为探讨水体中重金属对藻类的毒性影响,以普通小球藻(Chlorella vulgaris)和铬(Cr~(3+))为材料,研究不同浓度Cr~(3+)对普通小球藻生理、生化特性的影响,检测不同浓度的Cr~(3+)对小球藻的毒性效应。结果表明,小球藻的最优生长温度为31℃。此条件下,Cr~(3+)浓度为3 mg·L~(-1)时,小球藻的生物量最大。Cr~(3+)的浓度低于3 mg·L~(-1)时,Cr~(3+)能促进小球藻的生长,且藻细胞中光合色素、蛋白质、可溶性糖、丙二醛(MDA)的含量及超氧化物歧化酶(SOD)的活性也逐渐增加。当各胁迫组的Cr~(3+)浓度超过3 mg·L~(-1)时,随着Cr~(3+)浓度的提高,C.vulgaris的生长受到明显的抑制,藻细胞的光合色素、蛋白质和可溶性糖含量呈现逐渐下降的趋势,而MDA含量持续增加,SOD和脯氨酸则表现出先持续增高后降低(Cr~(3+)浓度为7 mg·L~(-1)时)的趋势。证明不同浓度的Cr~(3+)对小球藻的生理生化特性有不同程度的毒性效应。     

Multistep, microvolume resin fractionation combined with 3D fluorescence spectroscopy for improved DOM characterization and water quality monitoring

Conventionally, resin fractionation (RF) method has been widely used to characterize dissolved organic matter (DOM) found in different source waters based on general and broad DOM fractions grouping. In this study, a new refined method using multistep, microvolume resin fractionation combined with excitation emission matrix fluorescence spectroscopy (MSM-RF-EEMS) was developed for further isolation and characterization of subfractions within the primary DOM fractions separated from using the conventional RF method. Subsequently, its feasibility in indicating the occurrence of urban pollution in source waters was also assessed. Results from using the new MSM-RF-EEMS method strongly illustrated that several organic subfractions still exist within the regarded primary pure hydrophobic acid (HoA) fraction including the humic- and fulvic-like organic matters, tryptophan- and tyrosine-like proteins. It was found that by using the MSM-RF-EEMS method, the organic subfractions present within the primary DOM fraction could be easily identified and characterized. Further validation on the HoA fraction using the MSM-RF-EEMS method revealed that the constant association of EEM peak T1 (tryptophan) fraction could specifically be used to indicate the occurrence of urban pollution in source water. The correlation analysis on the presence of EEM peak T2 (tyrosine) fraction could be used as a supplementary proof to further verify the presence of urban pollution in source waters. These findings on using the presence of EEM peaks T1 and T2 within the primary HoA fraction would be significant and useful for developing a sensory device for online water quality monitoring.     

Urban stormwater harvesting and reuse: a probe into the chemical, toxicology and microbiological contaminants in water quality

Stormwater is one of the last major untapped urban water resources that can be exploited as an alternative water source in Australia. The information in the current Australian Guidelines for Water Recycling relating to stormwater harvesting and reuse only emphasises on a limited number of stormwater quality parameters. In order to supply stormwater as a source for higher value end-uses, a more comprehensive assessment on the potential public health risks has to be undertaken. Owing to the stochastic variations in rainfall, catchment hydrology and also the types of non-point pollution sources that can provide contaminants relating to different anthropogenic activities and catchment land uses, the characterisation of public health risks in stormwater is complex, tedious and not always possible through the conventional detection and analytical methods. In this study, a holistic approach was undertaken to assess the potential public health risks in urban stormwater samples from a medium-density residential catchment. A combined chemical–toxicological assessment was used to characterise the potential health risks arising from chemical contaminants, while a combination of standard culture methods and quantitative polymerase chain reaction (qPCR) methods was used for detection and quantification of faecal indicator bacteria (FIB) and pathogens in urban stormwater. Results showed that the concentration of chemical contaminants and associated toxicity were relatively low when benchmarked against other alternative water sources such as recycled wastewater. However, the concentrations of heavy metals particularly cadmium and lead have exceeded the Australian guideline values, indicating potential public health risks. Also, high numbers of FIB were detected in urban stormwater samples obtained from wet weather events. In addition, qPCR detection of human-related pathogens suggested there are frequent sewage ingressions into the urban stormwater runoff during wet weather events. Further water quality monitoring study will be conducted at different contrasting urban catchments in order to undertake a more comprehensive public health risk assessment for urban stormwater.     

Synergistic effect of N- and F-codoping on the structure and photocatalytic performance of TiO2

Three types of TiO₂ nanostructures were synthesized via a facile hydrolysis method at 195 °C. Effects of the preparation method and doping with N and F on the crystal structure and photocatalytic performance of TiO₂ were investigated. The nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller porosimetry, ultraviolet–visible diffuse reflectance spectroscopy and fluorescent emission spectra. Their photo-catalytic activity was examined by the photodegradation of methylene blue in aqueous solution under both ultra-violet and visible light irradiation. The results show that nitrogen and fluorine co-doped anatase TiO₂ had the characteristics of a smaller crystalline size, broader light absorption spectrum and lower charge recombination than pure TiO₂. Most importantly, more efficient photocatalytic activity under both ultra-violet and visible light was observed. The obtained N–F-TiO₂ nanomaterial shows considerable potential for water treatment under sunlight irradiation.