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991.
992.
Eight heavy metals (Cu, Zn, Fe, Mn, Cd, Cr, Ni, and Pb) in 14 different wild-growing edible mushroom species (Coprinus comatus, Voluariella volvacea, Pleurotus nebrodensis, Hypsizigus marmoreus, Hericium erinaceus, Agrocybe aegerita, Lenfinus edodes, Collybia velutipes, Agaricus bisporus, Russula albida, Clitocybe conglobata, Pleurotus eryngii, Lepista sordida, and Pleurotus ostreatus) collected from Yunnan province, China, were determined by inductively coupled plasma-atomic emission spectrometry after microwave digestion. All element concentrations were determined on a dry weight basis. The ranges of element concentrations for copper, zinc, iron, manganese, cadmium, chromium, nickel, and lead were 6.8-31.9, 42.9-94.3, 67.5-843, 13.5-113, 0.06-0.58, 10.7-42.7, 0.76-5.1, and 0.67-12.9 mg/kg, respectively. In general, iron content was higher than other metals in all mushroom species. The levels of zinc, cadmium, and lead in some edible mushroom samples were found to be higher than legal limits. The relative standard deviations were found below 10%. The accuracy of procedure was confirmed by certified reference material. 相似文献
993.
Polycyclic aromatic hydrocarbons in effluents from wastewater treatment plants and receiving streams in Tianjin, China 总被引:1,自引:0,他引:1
Weixiao Qi Huijuan Liu Jiuhui Qu Chengzhi Hu Huachun Lan Michael Berg Huimin Ren Wei Xu 《Environmental monitoring and assessment》2011,177(1-4):467-480
Surface water, suspended particulate matter, pore water, and sediment samples were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) in Yongding New River, South Drainage Canal and North Drainage Canal, which receive most of wastewater from industrial city of Tianjin. PAH concentrations in effluent samples of wastewater treatment plants (WTP) discharging into the South Drainage Canal and North Drainage Canal were quantified for the first time. The results showed that the discharge of the WTPs recently only contributed to the PAH contamination in the canals near the outlets of the WTPs. PAH levels in sediments of the streams were greatly higher than those in soils by riverbank probably due to receiving large amounts of untreated wastewater. Unusually high benz[a] anthracene concentration strongly influenced the seasonal and spatial variation of total PAH concentrations in South Drainage Canal. Paired samples t test of ??Nap, Fl, Phe, Fluo and ??Nap, Phe, Fluo, Chry concentrations, which were dominant components in the air samples from non-heating and heating season, respectively, in the suspended particulate matters from the streams showed that PAH source from air deposition was more important for Yongding New River than that for South Drainage Canal and North Drainage Canal. Source apportionment based on PAH profiles indicated that coal combustion was the major PAH contamination source, and coke oven sources and wood combustion also contributed to the PAH contamination of the streams. This was further indicated by organic petrography analysis. 相似文献
994.
温带阔叶红松林中不同树种和倒木对土壤性质的影响 总被引:1,自引:0,他引:1
以长白山温带阔叶红松林为研究对象,通过野外采集土壤样品,综合研究老龄树及倒木对周边表层土壤性质的影响。研究结果显示,在本研究样地条件下,不同树种周边的表层土壤性质存在显著性差异,红松(Pinus koraiensis)周边土壤中水溶性有机碳WSOC的质量分数和特征吸光系数SUVA254值都高于紫椴(乃砌amurensis)和水曲柳(Fraxinus mandshurica),但是土壤水溶性总氮WSTN和交换性无机氮的质量分数却是红松低于紫椴和水曲柳。对倒木影响的森林表层土壤性质的研究结果显示,倒木下方森林表层土壤中WSOC、WSTN以及交换性矿质氮的质量分数都明显地高于林间土壤,说明在小尺度空间区域内,倒木可能是森林表层土壤活性碳、氮库的重要输入源。此外,本研究还利用主成分分析探讨了受树种影响的森林表层土壤不同性质之间的关联性,并对树种和倒木影响周边土壤性质的可能性机制进行分析。 相似文献
995.
996.
997.
为减少化工事故频发造成严重人员伤亡及财产损失,在分析危化品泄漏事故类型的基础上,从事故发生概率和事故后果两方面提出危化品泄漏事故风险评估模型.以中毒事故为例,对重庆长寿化工园区内某企业一液氨储罐进行风险评估.基于概率模型计算中毒事故概率,结果表明该储罐发生泄漏引起中毒的概率较小;数值模拟结果显示:影响范围随时间的增加而... 相似文献
998.
综合交通枢纽运营安全集成管理机制的构建 总被引:2,自引:0,他引:2
为提高综合交通枢纽(ITH)运营安全管理的效率和效果,从脆弱性的角度,分析综合交通枢纽运营安全事故的机理和运营安全管理的特性,构建综合交通枢纽运营安全集成管理机制。该机制以安全信息、安全组织和安全资源的协调、集成和优化为核心,包含干扰监测、威胁预警、漏洞修复、事故控制、鲁棒性提升和应急与恢复等实施机制。建立包含管理措施和技术手段的支撑体系。研究表明:脆弱性是综合交通枢纽运营安全事故发生的根源;该机制以脆弱性为突破口,通过若干管理措施和技术手段,能够实现综合交通枢纽运营安全的全要素、全过程和全资源的集成管理。 相似文献
999.
Introduction
Crossover and rollover crashes in earth-divided, traversable medians on rural divided highways can lead to severe injury outcomes. This study estimated severity models of these two crash types. Vehicle, driver, roadway, and median cross-section design data were factors considered in the models. A unique aspect of the data used to estimate the models were the availability of median cross-slope data, which are not commonly included in roadway inventory data files.Methods
A binary logit model of cross-median crash severity and a multinomial logit model of rollover crash severity were estimated using five years of data from rural divided highways in Pennsylvania.Results
The highest probability of a fatal or major injury in cross-median and rollover crashes was found to occur in cases when a driver was not wearing a seatbelt. While flatter cross-slopes and narrower medians were associated with more severe cross-median crash outcomes, steeper cross-slopes and narrower medians significantly increased rollover crash severity outcomes. The presence of horizontal curves was associated with increased probabilities of high-severity outcomes in a median rollover crash.Impact on Industry
Modeling results in this study confirmed that cross-median and median rollover crash severity outcomes are associated with median cross-section design characteristics. Based on the estimated models, it appears that flatter and narrower medians lead to more severe injury outcomes in cross-median crashes. Steeper median cross-slopes and narrower medians were associated with higher probabilities of more severe outcomes in median rollover crashes. The results presented in this study suggest that there is a trade-off between median cross-section design and cross-median and rollover crashes in earth-divided, traversable medians on rural divided highways. While the severity models can be included in a framework to develop design guidance in relation to this trade-off, models of crash frequency should also be considered. 相似文献1000.
外源微生物对土壤中烟嘧磺隆的降解作用研究 总被引:3,自引:2,他引:1
为了探索外源微生物N80(Serratia marcecens)对烟嘧磺隆污染土壤生物修复的可行性,在实验室条件下,分析了温度、土壤pH值、接菌量、农药初始质量比等因素对N80降解烟嘧磺隆效果的影响.同时以小白菜、甜菜、菠菜为供试作物,采用室内盆栽试验法处理污染土壤,液相色谱仪(UVD)测定土壤中烟嘧磺降残留量.结果表明:1)向污染土壤中添加外源微生物菌株N80可以促进土壤中烟嘧磺隆的降解,第30d时,最高降解率可达79.7%;2)N80降解污染土壤中烟嘧磺隆的最适宜条件为25℃,pH=7.0,接种量108 cfu/g,初始质量比10mg/kg.研究表明,向污染土壤中接种一定量的外源微生物菌株N80可以有效降低土壤中烟嘧磺隆的残留量,减轻烟嘧磺隆对敏感作物的药害,达到了预期的生物修复效果. 相似文献