More than 100 t of nitrobenzene (NB) and related compounds were discharged into the Songhua River, the fourth longest river in China, because of the world-shaking explosion of an aniline production factory located in Jilin City on November 13, 2005. As one of the efforts to predict the fate of residual NB in the river, NB biodegradation abilities of the microbes in the water and sediments from different river sections were evaluated systematically. The results indicated that microbial communities from any section of the river, including one section at the upper stream of the NB discharging point, had the ability to biodegrade NB under aerobic (for river water samples) conditions at 22±1℃ or anaerobic (for sediment samples) conditions at 10±1℃. NB degradation rates of microbial communities in the downstream sites were markedly higher than those in the upstream site, indicating that the NB degradation abilities were enhanced because of the pollution of NB. Aerobic degradation got neglected at a temperature of 10℃ or lower. The production of nitrosobenzene and aniline during the aerobic biodegradation suggested the existence of at least two different NB degradation pathways, and the occurrence of the catechol-2,3-dioxygenase (C23O) gene and the significant decrease of dissolved organic carbon (DOC) indicated that NB could be mineralized under aerobic conditions. Although it was a fact that the river have frozen-up during the NB accident, it was speculated that biodegradation was not the major process responsible for the decrease of NB flux in the river. 相似文献
In this research, we constructed a three-dimensional fire risk analysis technique (3D-FRAT) for common building fires. To demonstrate its effect, the 3D-FRAT employed a self-developed 3D risk-calculating module in combination with the Fire Dynamics Simulator (FDS) software to simulate the Welcome Restaurant accident that happened on February 15, 1995 in Taichung City, Taiwan. This study only focuses on thermal radiation and provide a preliminary method to quantify a fire risk. Different firefighting equipment that comply with the related building and fire-preventive regulations have been used in the simulations to test their mitigating effectiveness on the accident. The results were shown by animation, 3D pictures, and sliced pictures to facilitate the researchers’ understanding of human hazards caused by thermal radiation or smoke in a specific fire accident. The minimal personnel escaping times for different hazardous factors were estimated; various firefighting designs that can reduce loss of human life and property were also perused. According to the simulation results, the individual risk values in Welcome Restaurant were between 3.108 × 10−9 to 2.719 × 10−5 (deaths/year). It is foreseeable that the 3D-FRAT can become a useful tool for related organizations to choose better fire-resistant buildings or fire-fighting equipment in the future. 相似文献
Objective: The objective of this study was to estimate the effect of the Brazilian zero-tolerance drinking and driving law on mortality rates due to road traffic accidents according to the type of victim, sex, and age.
Methods: An interrupted time series design was used to compare yearly mortality rates due to road traffic accidents in Rio de Janeiro, Brazil, before and after the zero-tolerance drinking and driving law came into effect on June 19, 2008. Yearly mortality rates were compared according to the type of victim: pedestrian, cyclist, motorcyclist, and vehicle occupant. We used the Prais-Winsten procedure of autoregression in the analysis of time series; the outcome of this analysis was the annual percentage change in the rates. Overall and stratified analyses were conducted to investigate whether the zero-tolerance drinking and driving law may have had a distributional effect on mortality rates due to road traffic accidents depending on sex and age group; a significance level of P < .01 was accepted.
Results: From 1999 to 2016, there were 15,629 deaths due to road traffic accidents in Rio de Janeiro. The effect of the zero-tolerance drinking and driving law on overall mortality rates due to road traffic accidents in Rio de Janeiro was not statistically significant. However, among cyclists and motorcyclists aged ≥60 years and among pedestrians of both sexes and aged ≥20 years, the effect of the zero-tolerance drinking and driving law was to decrease mortality due to road traffic accidents at a yearly rate.
Conclusion: There is evidence of reduced mortality rates due to road traffic accidents among cyclists and motorcyclists aged ≥60 years and among pedestrians of both sexes aged ≥20 years in the second major Brazilian capital 9 years after the zero-tolerance drinking and driving law was adopted. 相似文献