沙尘暴事件中大气颗粒物化学组分的浓度变化和硫酸盐的形成

应用电感耦合等离子体原子发射光谱、质谱和离子色谱分析了2002年3月28日-4月8日在山东长岛县采集的共11对粗、细大气颗粒物样品的化学组成,探讨4月6-8日沙尘暴事件中大气颗粒物化学组分的变化和硫酸盐的形成.沙尘暴事件应区分前锋和后续部分,前锋与大气中各种污染物相互作用,具有硫富集的特征.后续部分较好地保持了长距离传输风沙尘本身的特征.硫酸盐的形成机理可能是多相氧化而不是简单的酸碱中和.硫酸铵是首先生成的含硫物种,这是细颗粒主导的形成过程.硫酸铵逐渐转化为其他硫酸盐,硫的成分也逐渐向粗颗粒转移.在沙尘暴事件中含硫污染物不但有一个从气相向颗粒物转变的过程,也有一个从细颗粒向粗颗粒转化的过程.      

环境样品中杀菌剂的多残留分析

苯并咪唑类化合物(benzimidazoles)如涕必灵(thiabendazole)常作为杀菌剂普遍用在瓜果及农作物上．用液相色谱法分析这些物质比较困难：例如涕必灵,在硅胶基质的色谱柱上会发生严重的拖尾现象,酸性条件下尤为明显。涕必灵和多菌灵(carbendazim)在pH10的情况下使用XTerra MS C18色谱柱会得到较好的峰形,但在较高的pH值下,其它类型杀菌剂或杀虫剂可能不稳定,故难以用适合这些碱性杀菌剂的高pH值条件进行同时分析．     

Ozonation catalyzed by homogeneous and heterogeneous catalysts for degradation of DEHP in aqueous phase

Di-(2-ethyl hexyl) phthalate (DEHP), a recalcitrant and an endocrine disrupting chemical, was studied for its removal from wastewater by advanced oxidation process. The effects of pH, transition metal ions, and granular activated carbon (GAC) were investigated. Removal of DEHP increased with increase in pH and among metal ions Cr(III) was found to be the most active catalyst to remove DEHP. In the case of GAC, original carbon (G0) and GAC pre-ozonated in gas phase for 10 min (G10) were tested as catalysts in catalytic ozonation and found G0 to be more active than G10. This is because, during pre-ozonation, basic groups like chromene, pyrones and also graphene layers were oxidized to acidic surface oxygen groups. These basic surface groups are reported to be active catalytic centres for ozone decomposition into .OH which is a strong oxidant. According to kinetic manipulations, DEHP degradation rate constant due to .OH was affected by the catalyst while that due to direct ozonation is same in all cases with or without catalyst. G0 was doped with chromia gels (G0/CrA) to combine the benefits of homogeneous and heterogeneous catalysis. G0/CrA showed lower catalytic efficiency than that of only G0. This might be because of changes in surface structure of GAC caused by doping of chromia gel and changes in chemical nature of Cr(III) during formation of gel. A good correlation was found between the rate constants of ozone decay and DEHP degradation (R2=0.96). This correlation confirms that ozone decomposition into .OH is a critical factor for the activity of a catalyst during ozonation.     

Coupled infrared extinction spectra and size distribution measurements for several non-clay components of mineral dust aerosol (quartz, calcite, and dolomite)

Simultaneous size distributions and Fourier transform infrared (FTIR) extinction spectra have been measured for several representative components of mineral dust aerosol (quartz, calcite, and dolomite) in the fine particle size mode (D=0.1–1 μm). Optical constants drawn from the published literature have been used in combination with the experimentally determined size distributions to simulate the extinction spectra. In general, Mie theory does not accurately reproduce the peak position or band shape for the prominent IR resonance features in the 800–1600 cm⁻¹ spectral range. The resonance peaks in the Mie simulation are consistently blue shifted relative to the experimental spectra by 20–50 cm⁻¹. Spectral simulations, derived from a simple Rayleigh-based analytic theory for a “continuous distribution of ellipsoids” particle shape model, better reproduce the experimental spectra, despite the fact that the Rayleigh approximation is not strictly satisfied in these experiments. These results differ from our previous studies of particle shape effects in silicate clay mineral dust aerosols where a disk-shaped model for the particles was found to be more appropriate.     

Effectiveness of compacted soil liner as a gas barrier layer in the landfill final cover system

A compacted soil liner (CSL) has been widely used as a single barrier layer or a part of composite barrier layer in the landfill final cover system to prevent water infiltration into solid wastes for its acceptable hydraulic permeability. This study was conducted to test whether the CSL was also effective in prohibiting landfill gas emissions. For this purpose, three different compaction methods (i.e., reduced, standard, and modified Proctor methods) were used to prepare the soil specimens, with nitrogen as gas, and with water and heptane as liquid permeants. Measured gas permeability ranged from 2.03x10(-10) to 4.96x10(-9)cm(2), which was a magnitude of two or three orders greater than hydraulic permeability (9.60x10(-13) to 1.05x10(-11)cm(2)). The difference between gas and hydraulic permeabilities can be explained by gas slippage, which makes gas more permeable, and by soil-water interaction, which impedes water flow and then makes water less permeable. This explanation was also supported by the result that a liquid permeability measured with heptane as a non-polar liquid was similar to the intrinsic gas permeability. The data demonstrate that hydraulic requirement for the CSL is not enough to control the gas emissions from a landfill.     

Evaluation of marine outfall with three-dimensional hydrodynamic and water quality modeling

Numerical models are often used to evaluate the potential impact of human alternation of natural water bodies and to help the design of the alternation to mitigate its impacts. In the past decade, three-dimensional hydrodynamic and reactive transport modeling has matured from a research subject to a practical analysis technology. This paper presents a practical study in which a three-dimensional hydrodynamic and water quality model [hydrodynamic eutrophication model (HEM-3D)] was applied to determine the optimal location for treated wastewater discharged from marine outfall system in the Keelung harbor and the adjacent coastal sea. First, model validation was conducted with respect to surface elevation, current, and water quality variables measured in the Keelung harbor station and its coastal sea. The overall performance of the model was in qualitative agreement with the available field data. The model was then used to evaluate several scenarios of the locations from marine outfall system. Based on model simulation results, a location at the northeast of Ho-Ping Island was recommended for adoption because the environmental impact is smaller than any other alternative.

Public Nutrition in Emergencies: An Overview of Debates, Dilemmas and Decision-making

This paper introduces and discusses the main themes and issues arising from the workshop 'International Public Nutrition in Emergencies: The Potential for Improving Practice'.
Good co-ordination within the nutrition sector of the international humanitarian response system has led to a range of achievements in recent years. Major constraints to improving programme impact remain, however, including misconceptions about the scope of nutrition among the wider humanitarian system, which tends to give it a narrow focus on malnutrition and feeding people. In contrast to this limited view, the Public Nutrition approach brings a more broad-based emphasis to assessing and responding to nutritional problems in emergencies, and takes into account the wider social, economic and political causes of malnutrition.
Six case study presentations illustrated the various components of a Public Nutrition approach, including in-depth assessment, analysis and tailoring programmes accordingly. Additional presentations considered the nature of vulnerability, the concept of Public Nutrition, the responsibilities for addressing nutritional problems and some of the operational tools and frameworks in current use.
Participants agreed on the necessity of raising levels of awareness and understanding among all actors in the humanitarian sphere about the impact of their actions on nutrition. Strategies for achieving this included developing better multi-sectoral working relationships and also strengthening relationships with donors and key decision-makers in the humanitarian system. Other related strategies included institutional learning, training and capacity building, particularly in relation to institutions based in developing countries and building upon initiatives such as the Sphere Project, which has successfully brought together the various actors within the humanitarian system in order to improve quality of response.     

Behaviour of echinoid larvae around sharp haloclines: effects of the salinity gradient and dietary conditioning

We examined larval response to a range of sharp haloclines and determined the effect of dietary conditioning on that response in the sea urchins Echinometra lucunter and Arbacia punctulata. We reared larvae in the laboratory under a high or low concentration of either single (Isochrysis galbana) or mixed (Isochrysis galbana, Dunaliella tertiolecta, Thalassiosira weissflogii) microalgal species. For both species of sea urchins, rate of larval development was faster and age-specific larval length and width were greater in high-ration than low-ration diets. We examined the distribution of two- and four-arm larvae of E. lucunter from each diet treatment and of four-arm larvae of A. punctulata from the high-ration diets in cylinders with experimentally constructed haloclines. In three of the halocline treatments, the salinity of the bottom layer was 33‰ and that of the top layer was 21, 24 or 27‰ (21/33, 24/33 and 27/33) and in a fourth one, the salinities of the bottom and top layer were 30 and 21‰, respectively (21/30). The position of larvae in the cylinders varied with the steepness of the halocline and with dietary conditioning for both sea urchin species and all developmental stages tested. Significantly more larvae crossed the haloclines into water of 24 and 27‰ salinity than into water of 21‰ salinity. We observed an effect of diet on the position of larvae in the cylinders, and that effect varied among halocline treatments for both species. The proportion of larvae of E.lucunter that crossed the halocline was greater in low- than high-ration diets in the 24/33 and 27/33 treatments. Position of four-arm larvae in the cylinders also varied with food quality in high-ration diets: for E.lucunter in the 24/33 treatments, and for A. punctulata in the 21/30 treatments, more larvae from the single- than from the mixed-species diets were present above the halocline. Salinity in the adult habitat during most of the active reproductive period ranged from 15 to 40‰. We showed that larvae can respond to gradients in salinity, and therefore can remain within a water mass of higher salinity overlying the adult habitat. However, survival of poorly fed larvae may be increased if they are introduced into a new water mass and carried away from a nutritionally poor environment. Received: 9 July 1997 / Accepted: 12 January 1998     

First-trimester screening for Down syndrome; the role of nasal bone assessment in the Korean population

Objectives The aim of this study was to evaluate the role of nasal bone assessment in first-trimester screening for Down syndrome (DS) in the Korean population. Methods From July 2004 to March 2006, we prospectively evaluated the fetal nasal bones at 11–14 weeks' gestation in the Korean population. Results A successful evaluation was possible in 6490 of 6787 fetuses (95.6%). Absent, hypoechoic, and short nasal bones were seen in 4 (26.7%), 4 (26.7%), and 1 (6.7%) of 15 fetuses with DS, respectively, whereas in 5 (0.1%), 11 (0.2%), and 246 (3.8%) of 6456 normal fetuses. The incidence of absent and hypoechoic nasal bone showed significant differences between normal fetuses and fetuses with DS (P < 0.0005, both). Screening for DS using an absent or hypoechoic nasal bone resulted in a sensitivity of 53.3%, a specificity of 99.8%, a positive likelihood ratio of 215.2, and a negative likelihood ratio of 0.5. Conclusion Our study showed that nasal bone abnormality at 11–14 weeks of gestation had a high association with DS in the Korean population. This suggests that nasal bone assessment can be used to supplement the current first-trimester screening for DS in the Korean population. Copyright © 2007 John Wiley & Sons, Ltd.     

Influence of sponges on invertebrate recruitment: A field test of allelopathy

We manipulated live sponges in Belize, Central America, Big Pine Key, Florida (USA), and Indian River lagoon, Florida (USA) in summer/autumn, 1988. At each location, live sponges of three species were placed within 0.5 cm of ceramic tiles. Tiles with synthetic sponges positioned in the same manner and tiles with no sponges served as controls. Of 26 recruiting species analyzed, only one (Sponge sp. 6 — Indian River) was inhibited by living sponges. Four species (Perophora regina — Belize;Aiptasia pallida — Big Pine Key; andCrassostrea virginica andAscidia nigra — Indian River) recruited in greater numbers in the presence of sponges, suggesting that some larvae may be attracted rather than repelled by sponge allelochemicals. Allelopathic effects were less important than small-scale flow effects and patchy larval supply in determining recruitment patterns on surfaces adjacent to sponges.