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341.
利用火灾现场中燃烧物沉积物所特有的火灾原始信息,可以帮助火灾调查人员准确辨识与鉴别起火部位或起火点附近可燃物分部情况,辅助判断初始起火材料和起火部位的特点,通过燃烧模拟试验,开展了木材、化纤织物、棉织物、PVC制品、聚氨酯泡沫等常见固体可燃物燃烧沉积物微观形貌特征研究。首先,利用SEM 分析了不同材料沉积物中粒子分布、微观形貌等结构性差异。接着,进行了颗粒物的形貌学测量和组成成分测定。最终,得到了样本的量化差异特征。研究结果表明:5种固体可燃材料燃烧沉积物存在结构性差异,但并不显著;对组成粒子进行的形貌学测量和成分测定,可以量化区分材料属性。该方法可以为建立火灾现场起火部位可燃材料的燃烧时序性提供技术支持。 相似文献
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比较了稳健统计法和误差系数法在水中苯系物实验室间比对结果中的应用,分别采用两种方法对比对结果进行了分析,探讨了两种统计方法的差异和适用范围。结果显示,两种方法对此次比对结果的分析结论基本一致,在实际应用中应跟据实验室间比对的目的和样品特点选择合适的统计方法。 相似文献
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Rapid economic growth in the last two decades in Shanghai has had a great adverse influence on its air quality. Therefore, the atmospheric pollutants of Shanghai have received much concern. In this study, concentrations of 2,3,7,8-substituted PCDD/Fs and PBDD/Fs congeners were measured in the ambient air of four districts in Shanghai. The mean atmospheric concentrations (TEQs) of total 2,3,7,8-PCDD/Fs and 2,3,7,8-PBDD/Fs were 8031 fg m(-3) (497.1 fg I-TEQ m(-3)) and 1358 fg m(-3) (304.1 fg I-TEQ m(-3)) for Jiading District, 5308 fg m(-3) (289.0 fg I-TEQ m(-3)) and 709 fg m(-3) (146.9 fg I-TEQ m(-3)) for Zhabei District, 4014 fg m(-3) (144.4 fg I-TEQ m(-3)) and 1239 fg m(-3) (256.9 fg I-TEQ m(-3)) for Pudong District, 3348 fg m(-3) (143.2 fg I-TEQ m(-3)) and 699 fg m(-3) (148.4 fg I-TEQ m(-3)) for Huangpu District, respectively. Our results showed that almost all the PCDD/Fs and PBDD/Fs congeners were partitioned into the particulate phase except the lower chlorinated or brominated ones. The logarithm of the gas/particle partitioning coefficient K(p) has good linear correlation with that of the sub-cooled vapor pressure p(L). Concentrations of PCDD/Fs and PBDD/Fs were both positively correlated to elemental carbon in all districts except Pudong District, suggesting elemental carbon could be a good indicator for dioxins' air pollution. It is intensively suggested that more detailed and deeper studies about PBDD/Fs should be carried out due to their relatively high atmospheric concentrations in Shanghai. 相似文献
348.
A mathematical model was developed in this paper to describe the nonylphenol (NP) accumulation in the effluent of a wastewater recycling system. The model quantitatively presented the relationships among the NP concentrations in the raw wastewater and the system effluent, the number of wastewater recycling cycles, the water recycling ratio, the system NP removal efficiency, and the NP accumulation factor. The mathematical model was then verified through experimental modeling of a wastewater recycling process, and it was indicated that the Pearson correlation coefficient between mathematical simulation and experimental modeling results was 0.652. The study results indicated that the NP accumulation factor of a wastewater recycling system would approach a constant for large number of wastewater recycling cycles given the wastewater recycling ratio and system NP removal efficiency. The results also revealed that the NP concentration in the effluent increased with the wastewater recycling ratio given the system NP removal efficiency, and the increase of NP removal efficiency would decrease the NP accumulation in the system effluent under a given wastewater recycling ratio condition. The model was then applied to compute the maximum wastewater recycling ratio, predict reclaimed water quality and direct the design and management of sewage recycling systems in China. 相似文献
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土壤性质对单一及复合污染下外源镉稳定化过程的影响 总被引:4,自引:2,他引:4
通过对11个性质差异较大的土壤进行室内培养(土壤水分65%~70%WHC,温度25℃),观测了镉(Cd)单一和镉-铅(Cd-Pb)复合污染360 d内有效Cd含量随时间的变化,利用动力学模型对其稳定化过程进行模拟,并采用相关和逐步回归分析讨论了土壤理化性质对外源Cd稳定化过程的影响.结果表明,不同土壤中有效态Cd含量均在培养开始的15 d内迅速下降,随后变化减缓,培养60 d后基本达到平衡,其稳定化过程可用二级动力学方程、一阶指数衰减函数进行模拟.Pb的存在提高了Cd的有效性.模型的动力学参数稳定化平衡含量和表观速率常数可用来表征Cd的稳定化过程.土壤性质对这2个关键参数有显著影响,高pH值和高阳离子交换量(CEC)对Cd平衡含量有极显著的抑制作用,且pH值的直接抑制作用最大;土壤质地影响Cd的稳定化速率常数,在黏粒含量少、砂粒含量多的土壤中Cd能够更快达到平衡. 相似文献