Broadband UV spectroscopy system used for monitoring of SO2 and NO emissions from thermal power plants

A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO₂) and nitric oxide (NO) from a 220-ton h^?1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO₂ and NO from the CFB boiler fluctuated in the range of 750–1300 mg m^?3 and 100–220 mg m^?3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO₂ and lower for NO. The relatively high emission concentrations of SO₂ were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.     

Population dynamics,rural livelihoods and environmental degradation: some experiences from Tanzania

Population growth and environmental degradation are closely linked. Increasing population has in many rural areas of Tanzania contributed to changes in land use/cover patterns, land fragmentation and livelihood insecurity. Increasing demand for food, energy and other environmental services has contributed to expansion of agriculture, including marginal areas, and deforestation often leading to environmental degradation. Increased reliance on natural resources for rural livelihoods, subsistence nature of the agricultural sector and limited economic opportunities in rural areas are among the factors leading to rural–rural and rural–urban migrations searching for better livelihood opportunities. The high urban demand for food and biomass energy from rural areas has also contributed to rural deforestation and overall environmental degradation. This paper addresses the linkages between population and environmental degradation in Tanzania. It argues that effective implementation of development and resources management policies can lead to environmental sustainability even with growing populations. It provides evidence from successful land management interventions such as HADO, HASHI and SECAP, which support the argument that with effective implementation of resource management initiatives even larger populations can be supported by the available resources. Such successful interventions ought to be emulated elsewhere with similar environmental problems.     

The development of a more risk-sensitive and flexible airport safety area strategy: Part II. Accident location analysis and airport risk assessment case studies

This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing Airport Safety Areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The second part of the paper presents the analysis of accident locations, including the plotting of Complementary Cumulative Probability Distributions for the relevant accident types. These were then used in conjunction with the improved accident frequency models to produce Complementary Cumulative Frequency Distributions that could be used to assess risks related to specific runways and determine Airport Safety Area (ASA) dimensions necessary to meet a quantitative target level of safety. The approach not only takes into account risk factors previously ignored by standard risk assessments but also considers the operational and traffic characteristics of the runway concerned. The use of the improved risk assessment technique and risk management strategy using ASAs was also demonstrated in two case studies based on New York LaGuardia Airport and Boca Raton Airport in Florida.     

The development of a more risk-sensitive and flexible airport safety area strategy: Part I. The development of an improved accident frequency model

This two-part paper presents the development of an improved airport risk assessment methodology aimed at assessing risks related to aircraft accidents at and in the vicinity of airports and managing airport safety areas (ASAs) as a risk mitigation measure. The improved methodology is more quantitative, risk-sensitive, flexible and transparent than standard risk assessment approaches. As such, it contributes to the implementation of Safety Management Systems at airports, as stipulated by the International Civil Aviation Organisation.The first part of the paper presents the methodological advances made in the development of accident frequency models; namely the building of a single comprehensive database of all relevant accident types, the collection and use of normal operations data in quantifying the criticality of a series of risk factors, and modelling accident frequency using multivariate logistic regression. The resulting models have better goodness-of-fit, sensitivity and specificity than standard risk assessment methodologies.     

Emergency response study for chemical releases in the high-tech industry in Taiwan—A semiconductor plant example

In the past two decades, there has been continuous investment and expansion of semiconductor, photoelectric panel, or solar cell plants in the high-tech industry. For example, establishing a semiconductor plant costs about US$ 3 billion. In addition, the output value of integrated circuits (IC) of Taiwan as a whole is estimated to be about US$ 5.215 billion, and globally of US$ 275.2 billion in 2008. A large amount and a variety of specialty gases or chemicals are applied during processes in high-tech facilities and these chemicals are characterized by inflammability, toxicity, and corrosiveness. Accidents may result once errors or leaks occur in any part of the supply chain, which consists of storage facilities, supply equipment, process machines, and tail gas elimination devices. Personnel casualties can result in serious situations. This study discusses the emergency response procedures and common response defects in semiconductor plants with a view to enhancing emergency response effects and capabilities, avoiding casualties, reducing property loss and shortening operation interruption.     

Behavior of buoyancy and momentum controlled hydrogen jets and flames emitted into the quiescent atmosphere

As an effort to improve the prediction of hydrogen dispersion in the atmosphere, effects of buoyancy acting on the hydrogen jets formed by releasing from high pressure vessels are investigated analytically and experimentally. For the analytical study, an integral analysis for buoyant jets and flames is carried out to yield the closed formula describing the jet and flame shapes, including their trajectory and horizontal and vertical lengths corresponding to the critical concentrations. Because the density of hydrogen after releasing from high pressure storage conditions is much close to that of helium than that of hydrogen at room temperature, helium is used as the hydrogen surrogate for the buoyant jet experiments, which were performed by visualizing the jet dispersing in the atmosphere up to the jet Reynolds number Re ～ 2400. The trajectories obtained by the integral analysis and experiments agree relatively well until the transition to turbulence occurs. A further estimate for jets and flames is made by using the integral analysis as a preliminary design to the experiments involving a much greater hydrogen release. Once the comparative investigation of the larger scale experiments with the integral analysis, we anticipate that a more universal hydrogen jet and flame data can be obtained, which perhaps leads to a better safety distance of hydrogen stations.     

Effects of in utero di-butyl phthalate and butyl benzyl phthalate exposure on offspring development and male reproduction of rat

The study was conducted to assess the effects of in utero di-butyl phthalate (DBP) and butyl benzyl phthalate (BBP) exposure during late gestation on offspring’s development and reproductive system of male rats. Pregnant rats were treated orally with DBP (2, 10, 50 mg/kg), BBP (4, 20, 100 mg/kg), and diethylstilbestrol (DES) 6 μg/kg (positive control) from GD14 to parturition. A significant reduction in dams’ body weight on GD21 in DBP-, BBP-, and DES-treated groups was observed. The gestation length was considerably elevated in the treated groups. Decline in male pups’ body weight was significant at PND75 in DBP- (50 mg/kg), BBP- (20,100 mg/kg), and DES-treated groups. The weight of most of the reproductive organs and sperm quality parameters was impaired significantly in DBP- (50 mg/kg) and BBP- (100 mg/kg) treated groups. Further, a non-significant decline in testicular spermatid count and daily sperm production was also monitored in treated groups. A significant reduction in serum testosterone level in BBP (100 mg/kg), whereas the testicular activity of 17β-HSD was declined non-significantly in the treated groups with respect to control. The data suggests that DBP and BBP exposure during late gestation period might have adverse effects on offspring’s development, spermatogenesis, and steroidogenesis in adult rats.     

Comparison of stack measurement data from R&D facilities to regulatory criteria: A case study from PNNL

Chemical emissions from research and development (R&D) activities are difficult to estimate because of the large number of chemicals used and the potential for continual changes in processes. In this case study, stack measurements taken from R&D facilities at Pacific Northwest National Laboratory (PNNL) were examined, including extreme worst-case emissions estimates and alternate analyses using a Monte Carlo method that takes into account the full distribution of sampling results. The objective of this study was to develop techniques to estimate emissions from stack measurement data that take into account a high degree of variability in the actual emissions. The results from these analyses were then compared to emissions estimated from chemical inventories. Results showed that downwind ambient air concentrations calculated from the stack measurement data were below acceptable source impact levels (ASILs) for almost all compounds, even under extreme worst-case analyses. However, for compounds with averaging periods of a year, the unrealistic but simplifying extreme worst-case analysis often resulted in calculated emissions that were above the lower level regulatory criteria used to determine modeling requirements or to define trivial releases. Compounds with 24-hr averaging periods were nearly all several orders of magnitude below all, including the trivial release, criteria. The alternate analysis supplied a more realistic basis of comparison and an ability to explore effects under different operational modes.

Implications:

Air emissions from research operations are difficult to estimate because of the changing nature of research processes and the small quantity and wide variety of chemicals used. Stack measurements can be used to verify compliance with applicable regulatory criteria. This study shows that while extreme worst-case assumptions can be used for a relatively simple initial comparison, methods that take into account the full range of measurement data are needed to provide a more realistic estimate of emissions for comparison to regulatory criteria, particularly those criteria that define trivial levels of environmental concern.     

Response of photosynthetic and growth characteristic of Mosla chinensis and congenerous weed M. scabra to soil water content

Heterogeneity of precipitation could influence various physiological and ecological processes of plants. We present a comparative study on the ecophysiological responses of two congenerous species, Mosla chinensis (an endemic species) and M. scabra (a weedy species), to four soil water content (20%, 40%, 60% and 90% of water holding capacity (WHC), referred to as W20, W40, W60 and W90, respectively) to understand their ecophysiological responses and ecological differentiation. Results showed that both species grew well from W40 to W90, as they showed higher photosynthetic rate and biomass and bigger plants under these soil water content. However, biomass, chlorophyll a to b ratio (Chl _a/b) and root to shoot ratio (R/S) of M. scabra but not M. chinensis were significantly reduced under W20, indicating M. chinensis showed stronger capacity of sun-acclimation under severe drought than M. scabra. M. chinensis showed priority in adapting severe drought in comparison with M. scabra. We hypothesize that the different adaptive abilities to soil water content are partly responsible for their ecological differentiation observed in the field and may affect their fate in their native habitat.