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231.
Xuefeng Li Qixing Zhou Yi Luo Guang Yang Tong Zhou 《Environmental science and pollution research international》2013,20(2):957-966
Aquatic ecosystems are vulnerable to the exposure with petrochemicals such as toluene, ethylbenzene, and xylene (o-, m-, and p-xylene) (TEX) and their adverse effects. Considering the widespread use, occurrence, and high toxicity of TEX, the aim of this work was to investigate the differential toxicity of TEX against midge (Chironomus plumosus) larvae and reveal the joint action of binary and ternary mixtures of TEX using the predictive concentration addition model. More importantly, this research can afford the basic toxicity data and scientific reference for the establishment of water quality criteria or benchmark, water pollution control, and aquatic risk assessment. Single and joint toxic effects of TEX on C. plumosus larvae were investigated using a semi-static bioassay, and the type of joint effects of TEX was ascertained. In the single toxicant experiments, the toxicity of the three pollutants could be sequenced as ethylbenzene > xylene > toluene. Specifically, LC50s of T, E, and X after a 48-h exposure were 64.9, 37.8, and 42.0 mg/L, respectively. In the binary mixture experiments, the interaction between toluene and ethylbenzene, ethylbenzene and xylene, and toluene and xylene was largely in conformity with partial additive or additive effect as determined by isobologram representation and toxic unit models. In the ternary mixture experiments, the interaction was basically dependent on the use of additive index and mixture toxicity index methods. However, the antagonistic and synergistic actions were not significant. Thus, the tertiary mixture interaction could be regarded as additive action. The concentration addition model could successfully predict the joint action of TEX mixtures on C. plumosus larvae. Particularly, the additive action of TEX on C. plumosus larvae can be further recommended to evaluate water quality criteria of TEX. 相似文献
232.
Lei Tong Xu Liao Jinsheng Chen Hang Xiao Lingling Xu Fuwang Zhang Zhenchuan Niu Jianshuan Yu 《Environmental science and pollution research international》2013,20(4):2603-2615
With the rapid urbanization, the southeast coastal cities of China are facing increasing air pollution in the past decades. Large emissions of VOCs from vehicles and petrochemical factories have contributed greatly to the local air quality deterioration. Investigating the pollution characteristics of VOCs is of great significance to the environmental risk assessment and air quality improvement. Ambient VOC samples were collected simultaneously from nine coastal cities of southeast China using the Tedlar bags, and were subsequently preprocessed and analyzed using a cryogenic preconcentrator and a gas chromatography–mass spectrometry system, respectively. VOC compositions, spatial distributions, seasonal variations and ozone formation potentials (OPFs) were discussed. Results showed that methylene chloride, toluene, isopropyl alcohol and n-hexane were most abundant species, and oxygenated compounds, aromatics and halogenated hydrocarbons were most abundant chemical classes (62.5–95.6 % of TVOCs). Both industrial and vehicular exhausts might contribute greatly to the VOC emissions. The VOC levels in the southeast coastal cities of China were sufficiently high (e.g., 6.5 μg?m?3 for benzene) to pose a health risk to local people. A more serious pollution state was found in the southern cities of the study region, while higher VOC levels were usually observed in winter. The B/T ratio (0.26?±?0.09) was lower than the typical ratio (ca. 0.6) for roadside samples, while the B/E (1.6–7.6) and T/E (7.2–26.8) ratios were higher than other cities around the world, which indicated a unique emission profile in the study region. Besides, analysis on ozone formation potentials (OFPs) indicated that toluene was the most important species in ozone production with the accountabilities for total OFPs of 22.6 to 59.6 %. 相似文献
233.
本文采用超声-生化(两级好氧)联用的方法,对8-羟基喹啉废水的降解工艺进行了研究。对废水的预处理方法为超声降解法,文中分析了溶液初始浓度、超声时间、超声全程时间以及超声细胞粉碎机的变幅杆直径大小对废水预处理效果的影响。实验结果表明,变幅杆直径为25mm,溶液初始浓度为0.6g/L,超声全程时间在20min,最佳超声时间为2s时降解效率最高,CODcr去除率可以达到40.4%。本实验生化处理方法为普通活性污泥法(两级好氧),一级好氧反应池停留时间选择10h,去除率为69.4%;二级好氧反应池停留时间选择6h,去除率为71.7%。超声-生化(两级好氧)联用对8-羟基喹啉废水处理效果良好,CODcr总去除率达到94.4%。 相似文献
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在Ti(Ⅳ)和过氧化氢存在条件下,考察了臭氧化酸性苯乙酮溶液、硝基苯溶液和垃圾渗滤液(浙江衢州某垃圾填埋场)的预处理效能。结果表明,在pH2.86条件下,单独臭氧化处理对苯乙酮、硝基苯和垃圾渗滤液的COD去除率分别为10.1%、44%和28.6%。BOD,/COD值分别从原来的0.039、0.060和0.085提高到了0.130、0.158和0.174,仍属生化难降解废水。当体系加入Ti(Ⅳ)后,臭氧化苯乙酮和硝基苯的COD去除率分别达到了75.5%和65%,BOD;/COD则提高到了0.679和0.314,可生化性提升明显。对于垃圾渗滤液,只有当体系加入Ti(Ⅳ)和H22后,臭氧化COD的去除率达到66.6%,BOD、/COD提高至0.425。上述结果对酸性难降解废水的处理实际意义非常突出。 相似文献
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239.
文章介绍了三燃式危险废物焚烧技术,该新型焚烧炉采用回转热解窑作为一次燃烧处理方式,再由往复式炉排炉进行二次焚化燃烧,未燃尽的气体、粉尘进入三燃室充分分解燃烧,因此烧尽率高、热能效率高. 相似文献
240.
通过对近年来的城市燃气管道事故抢险统计数据的分析与研究,管道事故抢险方案的选择存在着很大的主观性和片面性.为了克服应急抢修方案的种种局限,笔者应用模糊综合评判方法建立了城市燃气管道事故应急抢修方案评价选择模型;考虑可靠性、抢修时间、事故损失、抢险费用、社会影响及政治影响等6类影响因素来评判抢修方案的优劣,可以科学合理地选择最佳的管道事故应急抢修方案,达到经济合理、快速可靠的目的;实例验证,评判模型对城市燃气管道事故抢险具有重要的现实意义和参考价值. 相似文献