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941.
Peroxyacyl nitrates (PANs) are important secondary pollutants in ground-level atmosphere. Accurate prediction of atmospheric pollutant concentrations is crucial to guide effective precautions for before and during specific pollution events. In this study, four models based on the back-propagation (BP) artificial neural network (ANN) and multiple linear regression (MLR) methods were used to predict the hourly average PAN concentrations at Peking University, Beijing, in 2014. The model inputs were atmospheric pollutant data and meteorological parameters. Model 3 using a BP-ANN based on the original variables achieved the best prediction results among the four models, with a correlation coefficient (R) of 0.7089, mean bias error of ? 0.0043 ppb, mean absolute error of 0.4836?ppb, root mean squared error of 0.5320?ppb, and Willmott's index of agreement of 0.8214. Based on a comparison of the performance indices of the MLR and BP-ANN models, we concluded that the BP-ANN model was able to capture the highly non-linear relationships between PAN concentration and the conventional atmospheric pollutant and meteorological parameters, providing more accurate results than the traditional MLR models did, with a markedly higher goodness of R. The selected meteorological and atmospheric pollutant parameters described a sufficient amount of PAN variation, and thus provided satisfactory prediction results. More specifically, the BP-ANN model performed very well for capturing the variation pattern when PAN concentrations were low. The findings of this study address some of the existing knowledge gaps in this research field and provide a theoretical basis for future regional air pollution control. 相似文献
942.
衍生化处理对于气相色谱检验环境中微量有机物有着重要的作用,酯化反应作为最常用的方法,正越来越广泛的运用在多种酸性物质的衍生化处理中。根据酯化反应催化原理,在实验中发现反应的最佳条件为:温度为80℃,选用硫酸氢钠或三氯化铁催化剂,催化剂用量为2g。 相似文献
943.
通过对舞阳、襄城凹陷原油及烃源岩样品的有机地化分析 ,研究了该区未熟油地球化学特征、判别标志及成因类型。认为盐湖盆地原油具“两高、两低”特征 ,族组成上表现为饱和烃含量较低 ,“非烃 +沥青质”含量较高。正烷烃呈双峰态分布 ,OEP值 >1。具植烷优势 ,Pr/Ph <0 .2 5。萜烷以伽玛蜡烷含量高 ,Tm/Ts >1。脱羟基维生素E普遍存在 ,其分布型式主要有倒“V”字型和不对称“V”字型。根据C2 9甾烷 2 0S/ (2 0S +2 0R) ,C2 9甾烷 ββ/ (ββ +αα) ,C3 2 藿烷 2 2S/ (2 2S +2 2R)等成熟度参数 ,认为原油属于未熟油。伽玛蜡烷、脱羟基维生素E及碳同位素组成特征反映原油属咸水湖相、盐湖相成因。 相似文献
944.
945.
冷凝法回收油气问题的探讨 总被引:12,自引:0,他引:12
彭国庆 《石油化工环境保护》1999,(2):30-33
着重探讨在石油化工厂中利用引进的DE4800型油气回收装置回收轻质油品装车系统油气的经济效益与社会效益 相似文献
946.
彭友德 《安全.健康和环境》2002,2(1):11-14
针对消防水系统存在的问题,进行了系统可靠性分析.从提高系统可靠性方面,提出了优化消防水系统结构,提高系统可靠性的改造方案,并论证实施后的效果. 相似文献
947.
948.
农药与未来农业的发展 总被引:6,自引:0,他引:6
评述现代农业生产中使用农药所带来的负面效果,对农作物,畜禽,人体及其他方面所造成的危害,阐明农业生产中减少农药用量,走持续发展道路的现实性和必要性。 相似文献
949.
The environmental effect of degraded ecosystem‘ s vegetation restoration in low subtropical China was studied. Results indicated that the vegetation recovery on degraded lands slgnificantly ameliorates surrounding environment, increases species diversity, improves soil structure, raises soil fertility, enhances productivity, and promotes regional agricultural production and social economic development dramatically. Through the combining engineering and biological measures, the restoration of degraded ecosystem in low subtropical area is possible and economical. The restoration experience in Xiaoliang, Wnhua and other sites are valuable for other degraded subtropical area was introduced. 相似文献
950.
Influence of nonionic surfactant on the solubilization and biodegradation of phenanthrene 总被引:4,自引:0,他引:4
Phenanthrene was solubilized in two different nonionic surfactants, Tween80 and Triton X-100. The bioavailability of phenanthrane to the bacteria isolated from the petroleum contaminated soils was studied based on the rotary flasks experiments. The results showed that the concentration of nonionic surfactants above the critical micelle concentration (CMC) can increase the solubility of phenanthrene in water andwere innoxious to the phenanthrene-degrading bacteria; phenanthrene solubilized in the micelles of Tween80 was bioavailable and biodegradable. The research demonstrated the potential of surfactant-enhanced bioremediation of soils contaminated by hydrophobic organic comoounds( HOCs). 相似文献