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661.
Hye-Jin Kim Kyung-Suk Cho Mark N. Goltz Jee-Hyeong Khim Jae Young Kim 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1237-1244
ABSTRACT To test the possible use of composted food waste and wastewater sludge as biofilters to treat gas-phase volatile organic compounds (VOCs), batch experiments were conducted with an isolated strain that could degrade aromatic compounds under aerobic conditions. A benzene and trichloroethylene (TCE) mixture was used as the gas-phase pollutant in experiments with composted food waste, sludge, and soil. Under aerobic conditions, benzene was degraded as a primary substrate and TCE was degraded cometabolically, with water contents varying from 6 to 60% (volume of water added/volume of solid). Optimal water content for VOC removal was 12% for the soil, 36% for the composted food waste, and 48% for the sludge. The extent of VOC sorption and biodegradation at the optimal water content was different for each material. With the same initial VOC concentration, more VOCs were removed by sorption onto the composted food waste and the sludge, while less VOCs were biodegraded in comparison with the results using soil. The reason the biodegradation in the soil was greater may be partly attributed to the fact that, due to less sorption, the aqueous-phase concentration of VOCs, which microorganisms could utilize as a carbon source or cometabolize, was higher. We also speculate that the distribution of microorganisms in each medium affects the rate of biodegradation. A large number of microorganisms were attached to the composted food waste and sludge. Mass transfer of VOCs and oxygen to these microorganisms, which appear to have been heterogeneously distributed in clusters, may have been limited, resulting in hindered biodegradation. 相似文献
662.
Thuli N. Mdluli Coleen H. Vogel 《Mitigation and Adaptation Strategies for Global Change》2010,15(3):205-222
South Africa faces several development challenges including those linked to climate change. Energy usage in South Africa,
for example, is already constrained because of a range of development challenges (the dependence on cheap coal as a heating
source; energy availability; access; affordability of alternative energy sources; and a range of health impacts, including
air pollution). Notwithstanding calls for a transition to a low carbon economy, there have been few, recent assessments in
South Africa of the costs associated with such a transition, particularly the social and economic costs for the poor who use
energy in a variety of ways. In this paper we focus on trying to unravel some of the complex energy-use behaviour including
understanding what drives consumers in resource-poor areas to choose and use persistently risky energy options. Analysis of
qualitative data in two township areas, Doornkop and Kwaguqa, shows that township households, whether electrified or not,
continue to burn coal. In both study areas, an estimated 80% of electrified households burn coal for space heating and cooking
and also make use of multiple fuel sources for a range of activities. Although the major obstacles preventing people from
discontinuing domestic coal combustion are poverty, the ready availability and social acceptability of coal together with
other social customs cannot be underrated. This paper therefore highlights some of the persistent challenges associated with
sustainable energy transitions in South Africa including implications for improved mitigation and adaptation for the energy
sector in wider climate change efforts. 相似文献
663.
664.
N. Selvaraju S. Pushpavanam N. Anu 《Environmental monitoring and assessment》2013,185(12):10115-10129
Rapid urbanization and population growth resulted in severe deterioration of air quality in most of the major cities in India. Therefore, it is essential to ascertain the contribution of various sources of air pollution to enable us to determine effective control policies. The present work focuses on the holistic approach of combining factor analysis (FA), positive matrix factorization (PMF), and chemical mass balance (CMB) for receptor modeling in order to identify the sources and their contributions in air quality studies. Insight from the emission inventory was used to remove subjectivity in source identification. Each approach has its own limitations. Factor analysis can identify qualitatively a minimal set of important factors which can account for the variations in the measured data. This step uses information from emission inventory to qualitatively match source profiles with factor loadings. This signifies the identification of dominant sources through factors. PMF gives source profiles and source contributions from the entire receptor data matrix. The data from FA is applied for rank reduction in PMF. Whenever multiple solutions exist, emission inventory identifies source profiles uniquely, so that they have a physical relevance. CMB identifies the source contributions obtained from FA and PMF. The novel approach proposed here overcomes the limitations of the individual methods in a synergistic way. The adopted methodology is found valid for a synthetic data and also the data of field study. 相似文献
665.
Bob Maaskant Sebastiaan N. Jonkman Laurens M. Bouwer 《Environmental Science & Policy》2009,12(2):157-169
Potential loss of life is considered an important indicator of flood risk. We examine the future development of potential loss of life due to flooding for a major flood prone area in The Netherlands. The analysis is based on projections and spatial distribution of population under a high economic growth scenario and a loss of life model. Results show that the projected population growth in flood prone areas is higher than average in the Netherlands between 2000 and 2040. Due to this effect the potential number of fatalities is projected to increase by 68% on average for 10 different flood scenarios, not including impacts from climate change and sea level rise. Just sea level rise of 0.30 m leads to an average 20% increase in the number of fatalities. The combined impact of sea level rise and population growth leads to an estimated doubling in the potential number of fatalities. Taking into account increasing probability of flooding due to sea level rise and extreme river discharges, the expected number of fatalities could quadruple by 2040. The presented results give a conservative and upper bound estimate of the increase of the risk level when no preventive measures are undertaken. It is found that the consideration of the exact spatial distribution of population growth is essential for arriving at reliable estimates of future risk of flooding. 相似文献
666.
667.
Exposure to inhaled THM: Comparison of continuous and event-specific exposure assessment for epidemiologic purposes 总被引:2,自引:0,他引:2
Trihalomethanes (THMs) (chloroform, bromoform, dibromochloromethane, and bromodichloromethane) are the most abundant by-products of chlorination. People are exposed to THMs through ingestion, dermal contact and inhalation. The objective of this study was to compare two methods for assessing THM inhalation: a direct method with personal monitors assessing continuous exposure and an indirect one with microenvironmental sampling and collection of time–activity data during the main event exposures: bathing, showering and swimming. This comparison was conducted to help plan a future epidemiologic study of the effects of THMs on the upper airways of children. 30 children aged from 4 to 10 years were included. They wore a 3M™ 3520 organic vapor monitor for 7 days. We sampled air in their bathrooms (during baths or showers) and in the indoor swimming pools they visited and recorded their time–activity patterns. We used stainless steel tubes full of Tenax® to collect air samples. All analyses were performed with Gas Chromatography and Mass Spectrometry (GC-MS). Chloroform was the THM with the highest concentrations in the air of both bathrooms and indoor swimming pools. Its continuous and event exposure measurements were significantly correlated (rs = 0.69 p < 0.001). Continuous exposures were higher than event exposures, suggesting that the event exposure method does not take into account some influential microenvironments. In an epidemiologic study, this might lead to random exposure misclassification, thus underestimation of the risk, and reduced statistical power. The continuous exposure method was difficult to implement because of its poor acceptability and the fragility of the personal monitors. These two points may also reduce the statistical power of an epidemiologic study. It would be useful to test the advantages and disadvantages of a second sample in the home or of modeling the baseline concentration of THM in the home to improve the event exposure method. 相似文献
668.
S.M. Eldridge C.R. Chen Z.H. Xu P.N. Nelson S.E. Boyd I. Meszaros K.Y. Chan 《Waste management (New York, N.Y.)》2013,33(11):2157-2169
Using solid state 13C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes. 相似文献
669.
Suresh Maddila Surjakanta Rana Ramakanth Pagadala Surya N. Maddila Chandrasekhar Vasam 《Journal of environmental science and health. Part. B》2013,48(8):571-583
Triclopyr is a widely used pesticide which is non-biodegradable and enters aquatic systems. The ozone facilitated photocatalyzed degradation and mineralization of Triclopyr using Au-loaded titania as heterogeneous catalyst is reported. The oxidative degradation activity of the hazardous pesticide was investigated at pH 7.8 under varied reaction conditions, including in presence and absence of ozone, titania alone, in presence and absence of light and with different loadings of Au on support. Photocatalysis with 2% Au/TiO2 in the presence of ozone yielded 100% degradation of Triclopyr in 2 h. The extent of degradation of pesticide and its mineralization were confirmed by GC-MS. For 10 mg/L of Triclopyr, 0.1 g/L of catalyst was found to be the optimum for mineralization. Results show that photocatalyzed ozonation with Au/TiO2 as catalyst is a very effective for its removal. No leaching of Au was observed in triplicate runs. Catalyst was fully recoverable and reusable with no loss of activity. 相似文献
670.
We explored the effect of varying pseudo-absence data in species distribution modelling using empirical data for four real species and simulated data for two imaginary species. In all analyses we used a fixed study area, a fixed set of environmental predictors and a fixed set of presence observations. Next, we added pseudo-absence data generated by different sampling designs and in different numbers to assess their relative importance for the output from the species distribution model. The sampling design strongly influenced the predictive performance of the models while the number of pseudo-absences had minimal effect on the predictive performance. We attribute much of these results to the relationship between the environmental range of the pseudo-absences (i.e. the extent of the environmental space being considered) and the environmental range of the presence observations (i.e. under which environmental conditions the species occurs). The number of generated pseudo-absences had a direct effect on the predicted probability, which translated to different distribution areas. Pseudo-absence observations that fell within grid cells with presence observations were purposely included in our analyses. We discourage the practice of excluding certain pseudo-absence data because it involves arbitrary assumptions about what are (un)suitable environments for the species being modelled. 相似文献