Transition metal-modified zinc oxides for UV and visible light photocatalysis

In order to use photocatalysis with solar light, finding more active and especially visible light active photocatalysts is a very important challenge. Also, studies of these photocatalysts should employ a standardized test procedure so that their results can be accurately compared and evaluated with one another. A systematic study of transition metal-modified zinc oxide was conducted to determine whether they are suitable as visible light photocatalysts. The photocatalytic activity of ZnO modified with eight different transition metals (Cu, Co, Fe, Mn, Ni, Ru, Ti, Zr) in three different concentrations (0.01, 0.1, and 1?at.%) was investigated under irradiation with UV as well as with visible light. The employed activity test is the gas-phase degradation of acetaldehyde as described by the ISO standard 22197-2. The results suggest that the UV activity can be improved with almost any modification element and that there exists an optimal modification ratio at about 0.1?at.%. Additionally, Mn- and Ru-modified ZnO display visible light activity. Especially the Ru-modified ZnO is highly active and surpasses the visible light activity of all studied titania standards. These findings suggest that modified zinc oxides may be a viable alternative to titanium dioxide-based catalysts for visible light photocatalysis. Eventually, possible underlying mechanisms are proposed and discussed.     

Spatial distribution and seasonal variation of char-EC and soot-EC in the atmosphere over China

A previous study on PM_2.5 carbonaceous aerosols measured with the thermal optical reflectance (TOR) method in fourteen Chinese cities is extended by subdividing total EC into char-EC and soot-EC. Average char-EC concentrations show great differences between the fourteen cities and between winter and summer periods, with concentrations of 8.67 and 2.41 μg m^?3 in winter and summer, respectively. Meanwhile spatial and seasonal soot-EC variations are small, with average concentrations of 1.26 and 1.21 μg m^?3 in winter and summer, respectively. Spatial and temporal distributions of char-EC, similar to EC, are mainly influenced by local fuel consumption, as well as the East Asian monsoon and some meteorological factors such as the mixing height and wet precipitation. The small spatial and seasonal variation of soot-EC is consistent with its regional-to-global dispersion, which may suggest that soot carbon is not local carbon, but regional carbon. Char-EC/soot-EC ratios show summer minimum and winter maximum in all cities, which is in good agreement with the difference in source contributions between the two periods. As OC/EC ratio is affected by the formation of the secondary organic aerosol (SOA), char-EC/soot-EC ratio is a more effective indicator for source identification of carbonaceous aerosol than previously used OC/EC ratio.     

Fish Mercury and Surface Water Sulfate Relationships in the Everglades Protection Area

Few published studies present data on relationships between fish mercury and surface or pore water sulfate concentrations, particularly on an ecosystem-wide basis. Resource managers can use these relationships to identify the sulfate conditions that contain fish with health-concerning total mercury (THg) levels and to evaluate the role of sulfate in methyl-mercury (MeHg) production. In this study, we derived relationships between THg in three fish trophic levels (mosquitofish, sunfish, and age-1 largemouth bass) and surface water sulfate from 1998 to 2009 for multiple stations across the Everglades Protection Area (EPA). Results show the relationship between sulfate and fish THg in each fish type is nonlinear and largely skewed, similar to the relationship between MeHg production and sulfate concentration in peatland sediment pore water identified by other researchers. Peak fish THg levels occurred in ~1 to 12 mg/L sulfate conditions. There was significant variability in the fish THg data, and there were several instances of high-fish THg levels in high-sulfate conditions (>30 mg/L). Health-concerning fish THg levels were present in all surface water sulfate conditions; however, most of these levels occurred in 1–20 mg/L sulfate. The data in this study, including recent studies, show consistent and identifiable areas of high- and low-fish THg across the spectrum of surface water sulfate concentration, therefore, applying an ecosystem-wide sulfur strategy may be an effective management approach as it would significantly reduce MeHg risk in the EPA.     

Exploring Land Developer Perspectives on Conservation Subdivision Design and Environmentally Sustainable Land Development

Insight into land developers’ perspectives on alternative residential developments and the barriers they experience in trying to develop them can be crucial in efforts to change environmentally damaging low-density, large-lot, and automobile-dependent residential patterns. Using a semi-structured interview instrument followed by short surveys, I examined the views of 16 developers in Waukesha County, WI, USA, a county that has experienced significant development pressures and widespread implementation of conservation subdivision design. The land developer investigation focused on conservation subdivision design familiarity and implementation, and identified a number of barriers that developers experienced in implementing the design. While the majority of the developers appeared familiar with the design and had experience developing conservation subdivisions, their motivations for developing them varied, as did their on-site conservation practices. The barriers included the lack of land use regulations supporting the design, economic factors, community opposition, and a lack of knowledge about sustainable residential development practices. Strategies to promote more environmentally sustainable residential land development patterns include providing a more supportive institutional environment, enacting different regulations and guidelines for natural resources protection, and offering education on ecologically sound development and planning practices.     

Sensitivity of future ozone concentrations in the northeast USA to regional climate change

An air quality modeling system was used to simulate the effects on ozone concentration in the northeast USA from climate changes projected through the end of the twenty-first century by the National Center for Atmospheric Research’s (NCAR’s) parallel climate model, a fully coupled general circulation model, under a higher and a lower scenario of future global changes in concentrations of radiatively active constituents. The air quality calculations were done with both a global chemistry-transport model and a regional air quality model focused on the northeast USA. The air quality simulations assumed no changes in regional anthropogenic emissions of the chemical species primarily involved in the chemical reactions of ozone creation and destruction, but only accounted for changes in the climate. Together, these idealized global and regional model simulations provide insights into the contribution of possible future climate changes on ozone. Over the coming century, summer climate is projected to be warmer and less cloudy for the northeast USA. These changes are considerably larger under the higher scenario as compared with the lower. Higher temperatures also increase biogenic emissions. Both mean daily and 8-h maximum ozone increase from the combination of three factors that tend to favor higher concentrations: (1) higher temperatures change the rates of reactions and photolysis rates important to the ozone chemistry; (2) lower cloudiness (higher solar radiation) increases the photolysis reaction rates; and (3) higher biogenic emissions increase the concentration of reactive species. Regional model simulations with two cumulus parameterizations produce ozone concentration changes that differ by approximately 10%, indicating that there is considerable uncertainty in the magnitude of changes due to uncertainties in how physical processes should be parameterized in the models. However, the overall effect of the climate changes simulated by these models – in the absence of reductions in regional anthropogenic emissions – would be to increase ozone concentrations.     

广州街道空气中挥发烃类特征和来源分析

采用固相吸附－热脱附－色谱／质谱检测器联用的方法分析了广州市街道空气中的发挥有机物。样品采自广州市区街道的３２个采样点,主要探讨了其中单环芳烃和正构烷烃的特征和可能来源;选取１３种烃类化合物进行进一步的因子分析,结果表明,这些挥发烃类可能主要来自汽油机车、工业和柴油机车的排放。多元线性回归分析表明３种源对所选挥发烃类的平均贡献分别为６４％、２３％和１３％。     

Isolation of five Rubrobacter strains from biodeteriorated monuments

In the last few years, the microbial colonisation of mural paintings in ancient monuments has been attracting the attention of microbiologists and conservators. The genus Rubrobacter is commonly found in biodeteriorated monuments, where it has been reported to cause rosy discolouration. However, to date, only three species of this genus have been isolated, all from thermophilic environments. In this paper, we studied three monuments: the Servilia and Postumio tombs in the Roman Necropolis of Carmona (Spain), and Vilar de Frades church (Portugal), in search of Rubrobacter strains. In all cases, biodeterioration and the formation of efflorescences were observed, and five Rubrobacter strains were isolated. These isolates showed different physiology and migration in denaturing gradient gel electrophoresis, suggesting they might represent new species within this genus. The isolates reproduced some biodeterioration processes in the laboratory and revealed their biomediation in crystal formation.