The light transmission and distribution in an optical fiber coated with TiO2 particles

The light delivery and distribution phenomena along the optical fiber coated with the P-25 TiO(2) particles by dipping was investigated. The surface properties (coverage, roughness and thickness) of the TiO(2) layer coated on the optical fiber were characterized by SEM micrographs. For TiO(2) layer prepared from solutions containing less than 20 wt.% of TiO(2) slurry, the thickness of layer was increased linearly with the TiO(2) slurry content in solutions. The UV light intensity transmitted along a TiO(2)-coated optical fiber decreased more rapidly than that transmitted along a non-coated fiber. Based on the experimental results, the light intensity distribution around a coated optical fiber was modeled to determine the optimum configuration for the design of optical fiber reactors under various operational conditions.     

An assessment of the emissions inventory processing systems EMS-2001 and SMOKE in grid-based air quality models

In the United States, emission processing models such as Emissions Modeling System-2001 (EMS-2001), Emissions Preprocessor System-Version 2.5 (EPS2.5), and the Sparse Matrix Operator Kernel Emissions (SMOKE) model are currently being used to generate gridded, hourly, speciated emission inputs for urban and regional-scale photochemical models from aggregated pollutant inventories. In this study, two models, EMS-2001 and SMOKE, were applied with their default internal data sets to process a common inventory database for a high ozone (O3) episode over the eastern United States using the Carbon Bond IV (CB4) chemical speciation mechanism. A comparison of the emissions processed by these systems shows differences in all three of the major processing steps performed by the two models (i.e., in temporal allocation, spatial allocation, and chemical speciation). Results from a simulation with a photochemical model using these two sets of emissions indicate differences on the order of +/- 20 ppb in the predicted 1-hr daily maximum O3 concentrations. It is therefore critical to develop and implement more common and synchronized temporal, spatial, and speciation cross-reference systems such that the processes within each emissions model converge toward reasonably similar results. This would also help to increase confidence in the validity of photochemical grid model results by reducing one aspect of modeling uncertainty.     

红壤丘陵区LAI与土壤侵蚀分布特征的关系

叶面积指数(LAI)是常用的一个用于描述植被覆盖的方面指数,土壤侵蚀的分布又与植被的覆盖状况息息相关,这就意味着LAI与土壤侵蚀有一定的相关性,目前有关这二者的相关性研究还鲜有文献报道。基于这此,本研究首先利用2000年的遥感影像(TM)解释出该年度的土壤侵蚀强度图,再利用该遥感影像通过图像的代数运算得出该地区的NDVI栅格图,通过实测该县不同典型植被条件的LAI值,得出实测的LAI与图像NDVI值之间的函数关系式,由图像的代数运算把NDVI图转换成LAI图,即实现了遥感图像的实测LAI纠正。在GIS软件的帮助下,通过将LAI栅格图与土壤侵蚀强度图的空间叠加分析,得到不同LAI条件下的土壤侵蚀分布。结果表明,LAI与土壤侵蚀的分布表现为:大致以LAI=2为分界线,当LAI<2时,土壤侵蚀并未随LAI的增加而迅速减少,LAI>2时,土壤侵蚀的分布随植被指数的增加而减少,当LAI=2左右时,土壤侵蚀的面积最大。这种情况对于轻度、中度及强度土壤侵蚀的影响是类似的,都呈类正态分布的曲线形式,但在曲线的两侧土壤侵蚀类型是有本质区别的,在曲线的左侧土壤侵蚀类型的分布是中度和强度为主,而在曲线右侧则以轻度为主。表明LAI这个指标与土壤侵蚀有很好的相关性,可以用于土壤侵蚀方面的相关研究工作。     

Boundary Layer Evolution and its Influence on Ground-Level Ozone Concentrations

Accurate determination of the planetary boundary layer (PBL) height (i.e., mixing height (MH)) is critical to properly simulating pollutant levels with the grid-based photochemical models. In this study, the daytime mixing heights based on the parcel and bulk Richardson number methods are compared with those obtained directly from a numerical mesoscale meteorological model in an effort to evaluate the uncertainties in the estimation of the PBL evolution. Mixing heights are estimated from hourly outputs of meteorological variables of the Penn State/NCAR Mesoscale Model Version 3.3 (MM5V3) with two PBL schemes (Blackadar and Gayno-Seaman) during July 1999 over Philadelphia, PA. An analysis of the diurnal variation in the urban PBL and its influence on ground-level ozone (O₃) levels is presented in this paper. The results indicate that on average, the MHs determined from the bulk Richardson number were larger than those estimated from the parcel method. The MHs from the MM5V3 output were much smaller than those derived from the parcel and bulk Richardson number methods, especially for the Gayno-Seaman scheme that is based on turbulent kinetic energy. The MH and ground-level O₃ concentration have been found to be twice as much on episode days than on non-episode days. The average hourly MH growth rate and O₃ tendency (i.e. rate of change in O₃) were largest during the morning hours (0700 to 1000 eastern standard time (EST)), suggesting that vertical mixing contributes significantly to the accumulation of ground-level O₃ in urban areas in the morning hours.     

PM2.5 exposure induces age-dependent hepatic lipid metabolism disorder in female mice

Particulate matter exposure has been described to elevate the risk of lung and cardiovascular diseases.An increasing number of recent studies have indicated positive correlations between PM_(2.5)(the fraction of airborne particles with an aerodynamic diameter less than2.5 μm) exposure and the risk of liver diseases.However,research on the effects of PM_(2.5)exposure on liver fat synthesis,secretion,and clearance mechanisms under normal diet conditions is limited,and whether these effects are age-dependent is largely unknown.Female C57BL/6 mice at different ages(4 weeks(4 w),4 months(4 m),and 10 months(10 m))were treated with 3 mg/kg body weight of PM_(2.5) every other day for 4 weeks.Subsequently,the ultrastructural changes of liver,the expression of genes involved in oxidative damage and lipid metabolism in the liver were examined.Observation of hepatic ultrastructure showed more and larger lipid droplets in the livers of 4-week-old and 10-month-old mice exposed to PM_(2.5).Further analysis showed that PM_(2.5) exposure increased the expression of genes related to lipid synthesis,but decreased the expression of genes involved in lipid transport and catabolism in the livers of 10-month-old mice.Our findings suggest that exposure to PM_(2.5) disrupts the normal metabolism of liver lipids and induces lipid accumulation in the liver of female mice in an age-dependent manner,with older mice being more susceptible to PM_(2.5).     

Quality of groundwater contaminated by leachates from seven Polish landfills – chemical and ecotoxicological classifications

The article presents the results of screening research on acute toxicity of groundwater contaminated by leachates to the bacterium Vibrio fischeri (ToxAlert 100® test) and crustacean Daphnia magna (Daphtoxkit F? magna test according to PN-EN ISO 6341), as well as on chronic toxicity to D. magna (test according to ISO 10706). The groundwater samples were taken from seven large city landfills in the Pomeranian province (Poland), which were open before 1990 and designed without proper attention to being leak-tight. Due to the lack of either European or Polish classification of ecotoxicological qualities of surface and underground waters, an attempt was made to evaluate the ecotoxicological quality of the examined waters on the basis of the Helsinki Committee's recommendations for industrial effluents, the classification of sediment according to Krebs (Krebs F. The pT-value as a classification index in aquatic toxicology. GIT Edition Umweltanalytik-Umweltschutz 1988;1:57–63) and the classification system of toxicity levels for natural waters and sewers, recently proposed by Persoone et al. (Persoone G, Marsalek B, Blinova, I, Törökne A, Zarina D, Manusadzianas L, Nalecz-Jawecki G, Tofan L, Stepanova N, Tothova L, Kolar B. A practical and user-friendly toxicity classification system with microbiotests for natural waters and wastewaters. Environ. Toxicol. 2003;18 (6):395-402).     

Fates and partitioning of heavy metals in municipal solid waste incineration process

The fate and partitioning of heavy metals (including Hg, Cd, Pb, Zn, As, Cr, Ni, and Cu) from MSW incinerators located in Taiwan were determined. Results of stack sampling indicate that most Hg and As (more than 80%) exists in the gas phase while other metals partition differently among bottom ash, fly ash, and flue gases. Removal efficiencies of existing air pollution control devices for Hg and As are lower (about 70%) than other metals. Bottom ash contains higher concentration of Cd compared with European incinerators. In addition, strong enrichment of Cd on fly ash particles is observed.     

Development of novel environmental friendly polyurethane foams

To prepare materials with improved recycling capability, new flexible biodegradable polyurethane foams, in which non-degradable polyether polyol was partly substituted by the bio-polyols based on cellulose or starch derivatives were synthesized. The incorporation of bio-polyols into the foams’ structures as well as their influence on the foam thermal stability was assessed by Fourier-transformed infrared spectroscopy and thermogravimetric analysis analyses. The ecotoxicological aspects of the newly synthesized foams were investigated by extracting the samples using freshwater as a solvent followed by applying the microbiotest screening toxkit under trade name “Thamnotoxkit F?” with larvae of freshwater shrimps Thamnocephalus platyurus.     

Frontier science and challenges on offshore carbon storage

● The main direct seal up carbon options and challenges are reviewed. ● Ocean-based CO₂ replacement for CH₄/oil exploitation is presented. ● Scale-advantage of offshore CCS hub is discussed. Carbon capture and storage (CCS) technology is an imperative, strategic, and constitutive method to considerably reduce anthropogenic CO₂ emissions and alleviate climate change issues. The ocean is the largest active carbon bank and an essential energy source on the Earth’s surface. Compared to oceanic nature-based carbon dioxide removal (CDR), carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems. This review focuses on the recent state-of-the-art developments in offshore carbon storage. It first discusses the current status and development prospects of CCS, associated with the challenges and uncertainties of oceanic nature-based CDR. The second section outlines the mechanisms, sites, advantages, and ecologic hazards of direct offshore CO₂ injection. The third section emphasizes the mechanisms, schemes, influencing factors, and recovery efficiency of ocean-based CO₂-CH₄ replacement and CO₂-enhanced oil recovery are reviewed. In addition, this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCS hubs. Finally, the upsides, limitations, and prospects for further investigation of offshore CO₂ storage are presented.     

MOE法在土壤侵蚀危险评价中的应用

影响土壤侵蚀的因索很多,有自然因素(如地形、植被、土壤、降雨等)和人为因素,这些因素中既有量化指标如坡度、降雨等自然因素,也有土地利用、土壤母质等不可量化的指标.这些因素的共同作用,使得单纯在GIS下利用叠加的方法对土壤侵蚀潜在危险进行判别带来一定的困难(如人为因素的最化问题等).多标准评价法(Multi-Criteria Evaluation,MCE)可以将难以量化的指标进行量化处理,并综合考虑多种囚素埘口标的影响,通过加权线性合并及布尔叠加的方法,在众多因素或是相互矛盾的客观实际中确定一种折中的优化方案,来对目标作出客观的评价.主要介绍了多标准评价法的概念及其方法原理,并以江西兴国县为例,介绍了该方法在土壤侵蚀评价中的实现过程.在土壤侵蚀评价因子的选用上,先取了植被指数(LAI)、土地利用、坡度、土壤母质、高程、道路、降雨及人口密度八个因子,根据实际情况确定单个因子在不同指标水平下可能造成的潜在土壤侵蚀危险等级;然后将因子组成矩阵,通过两两比较,来判断各因子的权重;把权重与相应的因子图相乘得到带权重值因子的栅格图,这些栅格图再进行统一的标准化处理,最后将标准化处理的栅格图通过叠加生成潜在侵蚀危险分布图.结果表明,兴国县大部分是微度侵蚀危险地区,呈连片分布,中、低度侵蚀危险主要分布在平原及沟谷地带,呈零星态,二者呈相互交错.微度危险、低度危险及中度危险区域分别占兴国县总面积的37.9%、29.2%及30.4%.三者之和为97.5%,高侵蚀危险及极高侵蚀危险的面积只占2.5%,且呈零星分布.这与兴国县的土壤侵蚀分布现状基本一致,多标准评价法应用在土壤侵蚀危险评价上是切实可行的.