H4SiW12O40/TiO2/beads光催化降解亚甲基蓝的研究

以钛酸四丁酯为原料,空心微珠为载体,采用溶胶凝胶法制备TiO₂/beads光催化剂载体,然后浸渍法制备出H₄SiW₁₂O₄₀/TiO₂/beads表面负载修饰型复合光催化剂,并运用SEM、XRD、FT-IR和DRS对催化剂进行表征和分析。研究了H₄SiW₁₂O₄₀/TiO₂/beads对亚甲基蓝降解的光催化活性,考察了光强度、pH值、曝气量、底物浓度和催化剂用量等对催化效率的影响。实验结果表明,在中性条件下,H₄SiW₁₂O₄₀/TiO₂/beads催化剂的投加量为0.25 g/L,浓度为7.5 mg/L的亚甲基蓝溶液在250 W的紫外灯和600 W的可见光灯下光照60 min降解率分别可达到94.5%和55%。     

The Tucson Mineral Show and the market for collector minerals: The potential for artisanal and small scale miners

Minerals that are sold to collectors are often produced by artisanal and small scale miners in many developing countries. The market for collector minerals is not well understood by most government agencies or NGOs but has a large impact on the artisanal and small miners that have the opportunity to produce these minerals because of the high prices that can be realized. This paper describes the collector mineral market that is held annually in Tucson, Arizona, that analyzes the competitive forces that affect the profitability of the mineral dealers at the show and describes potential methods for artisanal and small scale miners to participate successfully in the show. Most collector minerals produced by artisanal and small-scale miners are valued for their aesthetic qualities instead of mineral content. The 43 shows that operate during the first two weeks in February make up the largest gem and mineral show in the world, the Tucson Show. The Tucson Mineral Show is a subgroup of six shows that specialize primarily in collector minerals.There are several competitive forces at the Tucson Mineral Show that can affect the profit potential of dealers that participate in the show. These forces include potential entrants, suppliers, buyers, substitutes, and rivalry among existing competitors. New entrants face several barriers to entering the market place including the supply side economies of scale, demand side benefits of scale, and capital requirements. Because of these barriers, the cost of doing business and the way that promoters organize and manage the shows, it is difficult for artisanal and small scale miners to enter the show and compete with established dealers. However, with support from entities such as local governments, non-profit organizations, and international organizations the artisanal and small scale miners have the potential to have their minerals sold at the Tucson Shows for prices that would be greater than what can be achieved in the local market. Methods to help the artisanal and small scale miners compete include direct sales or consignments to retail dealers, tailgating, development of sales co-operatives, and the creation of an artisanal/small scale mineral show.     

近40年来中国自然灾害的时空统计特征

利用约2000个中国自然灾害记录,我们计算分析得到了中国自然灾害的统计规律,它们可总结为:1.中国的灾害可以以胡焕庸线和34°N为界划分为西域、北域、南域三个区,并且沿胡线可能存在过渡带区域;2.中国自然灾害的月特征是旱灾主要发生于3-10月,洪涝主要发生于6-9月;3.灾害的最频发区位于黄淮海地区。     

Validation of the stomatal flux approach for the assessment of ozone visible injury in young forest trees. Results from the TOP (transboundary ozone pollution) experiment at Curno, Italy

This paper summarises some of the main results of a two-year experiment carried out in an Open-Top Chambers facility in Northern Italy. Seedlings of Populus nigra, Fagus sylvatica, Quercus robur and Fraxinus excelsior have been subjected to different ozone treatments (charcoal-filtered and non-filtered air) and soil moisture regimes (irrigated and non-irrigated plots). Stomatal conductance models were applied and parameterised under South Alpine environmental conditions and stomatal ozone fluxes have been calculated.The flux-based approach provided a better performance than AOT40 in predicting the onset of foliar visible injuries. Critical flux levels, related to visible leaf injury, are proposed for P. nigra and F. sylvatica (ranging between 30 and 33 mmol O₃ m⁻²). Soil water stress delayed visible injury appearance and development by limiting ozone uptake. Data from charcoal-filtered treatments suggest the existence of an hourly flux threshold, below which may occur a complete ozone detoxification.     

Ozone Deposition to a Coniferous and Deciduous Forest in the Czech Republic

Estimates of ozone concentration and deposition flux to coniferous and deciduous forest in the Czech Republic on a 1 × 1 km grid during growing season (April–September) of the year 2001 are presented. Ozone deposition flux was derived from ozone concentrations in the atmosphere and from its deposition velocities. To quantify the spatial pattern in surface concentrations at 1 km resolution incorporating topography, empirical methods are used. The procedure maps ozone concentrations from the period of the day when measurements are representative for the forest areas of countryside. The effects of boundary layer stability are quantified using the observed relationship between the diurnal variability of surface ozone concentration and altitude. Ozone deposition velocities were calculated according to a multiple resistance model incorporating aerodynamic resistance (R _a ), laminar layer resistance (R _b ) and surface resistance (R _c ). Surface resistance (R _c ) comprises stomatal resistance (R _sto ). R _sto was calculated with respect to global radiation, surface air temperature and land cover. Modelled total and stomatal ozone fluxes are compared with the maps describing equivalent values of AOT40 (accumulated exposure over threshold of 40 ppb). For forests, the critical level (9,000 ppbh May–July daylight hours) is exceeded over 50% of forested territory. This indicates the potential for effects on large areas of forest. There is significiant correspondence between the exposure index AOT40 and the total ozone flux, but the relation between the total ozone flux and AOT40 exposure index is not clear in all parts of the forest territory.     

MODIS气溶胶光学厚度对城市空气质量的指示

空气污染指数API(Air Pollution Index)是关系大众生产生活的一个重要指标,论证了一种由MODIS(中分辨率成像光谱仪)反演的气溶胶光学厚度产品AOT(Aerosol Optics Thickness)预报空气质量的方法,即依据API的分级标准,将API用特定的步长分组,再把各组的AOT和API均值建立相关模型,并用该模型来预测空气质量指数,经验证,预测值和实际值之间的精度为77.59%,基本达到业务运行的要求。     

湖南骑田岭岩体北东部角闪石黑云母二长花岗岩的40Ar-39Ar定年及其意义

对骑田岭岩体主体仰天湖单元粗中粒斑状角闪石黑云母二长花岗岩进行了黑云母40Ar-39Ar年龄测定,获得坪年龄为(155.1±1.8)Ma,等时线年龄为(154.7±1.8)Ma.该年龄样品提高了骑田岭岩体形成时代的面上控制程度,与前人有关高精度年代资料一起说明骑田岭序列为中侏罗世末-晚侏罗世初形成的大岩基,基本排除其内部有其它时代成分的可能.结合骑田岭地区锡矿与花岗岩的关系,认为江口一带具有寻找锡矿的前景.     

Ozone distribution in central Italy and its effect on crop productivity

The focus of the present study was to assess the ozone levels in a typical area of the Mediterranean basin, viz. Tuscany (central Italy). Eighty-thousand hourly mean ozone concentrations were recorded by 10 automatic analysers in the districts of Florence, Pisa, Lucca and Prato, from May to September 1995 to 1997. The highest daily mean concentrations were reached in Florence, with a maximum hourly average of 197 ppb. In Lucca and Pisa, the peaks were close to 100 ppb. Data from Prato were much lower. Long-term critical levels for vegetation, as set by United Nations Economic Commission for Europe (UNECE), were constantly exceeded in Florence and Pisa, occasionally in Lucca, never in Prato. The results were used to fit exposure/yield response relationships proposed by UNECE and US National Crop Loss Assessment Network for some important crops. The estimated yield losses varied in Florence from 8% for corn and alfalfa to 27% for soybean, in Pisa from 5% for corn to 24% for soybean, in Lucca from 3% for corn to 17% for soybean. A preliminary economic estimate for corn, wheat, barley, soybean, tomato and alfalfa, calculated annual damage to be 4.6 M Euro in Florence, 0.5 M Euro in Lucca and 3 M Euro in Pisa. The picture must be regarded as only partial, as exposure/yield response relationships for important Italian crops (such as grapevine and vegetables) are not available.     

气候变化情景下地表O3对水稻产量的潜在风险评估

利用2013~2015年水稻生长季期间气象因子、O₃浓度和气孔导度的实测数据,分析了O₃浓度与AOT40的变化,引入并修订了水稻气孔导度模型,模拟了水稻气孔O₃吸收通量的动态变化,评估了当前和未来气候变化情景下O₃污染所造成的水稻产量损失.结果表明：2013~2015年水稻生长季期间的白天时段,平均O₃浓度分别为35.8,42.0,47.9nL/L,AOT40值分别为5.33,9.03,11.25μL/（L·h）.修订后的模型可用于本地区水稻气孔导度的模拟,2013~2015年水稻气孔O₃通量AF_st02分别为2.02,6.42,7.79mmol/m².2013~2015年地表O₃造成水稻平均相对产量损失分别为4.9%、11.7%和14.3%.在未来气候变化情景下若不考虑O₃浓度的变化,O₃对水稻的胁迫效应将会降低,若考虑未来O₃浓度的变化,O₃造成水稻产量的损失将增加4.7~5.7%.     

高级氧化技术处理垃圾渗滤液的研究进展

垃圾渗滤液是一种成分复杂、有机物、氨氮浓度高的难处理废水,介绍了高级氧化技术在垃圾渗滤液处理中的研究与应用现状。主要介绍了臭氧氧化、光催化氧化、Fenton试剂、电氧化以及湿式氧化在处理垃圾渗滤液中的应用,分析了高级氧化技术处理垃圾渗滤液的原理,对国内外各种氧化技术在垃圾渗滤液处理中的应用进行了总结,并探讨了它们的优缺点。最后,提出了当前应用高级氧化技术处理垃圾渗滤液所存在的问题和发展方向。