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161.
随着国家节能减排工作的大力推进,COD作为减排中四个重要约束性指标之一,其分析的准确性极大地影响着COD减排工作的顺利实施。本文根据《水质化学需氧量的测定重铬酸盐法》(GB11914—89),结合《水质采样技术指导》(HJ494-2009)要求及笔者多年COD分析测试工作经验,着重探讨重铬酸盐法中水样中悬浮物及氯离子对测定结果的影响,以求在实际工作中能更准确、更方便地完成水样中COD的分析工作。 相似文献
162.
Hong Zhao Yunshan Ge Tiezhu Zhang Jipeng Zhang Jianwei Tan Hongxin Zhang 《环境科学学报(英文版)》2014,26(10):2027-2033
The alteration and formation of toxic compounds and potential changes in the toxicity of emissions when using after-treatment technologies have gained wide attention. Volatile organic compound(VOC), carbonyl compound and particle-phase polycyclic aromatic hydrocarbon(PAH) emissions were tested at European Steady State Cycle(ESC) to study unregulated emissions from a diesel engine with a fuel-borne catalyst and diesel particulate filter(FBC–DPF). An Fe-based fuel-borne catalyst was used for this study. According to the results, brake specific emissions of total VOCs without and with DPF were 4.7 and4.9 mg/kWh, respectively, showing a 4.3% increase. Benzene and n-undecane emissions increased and toluene emission decreased, while other individual VOC emissions basically had no change. When retrofitted with the FBC–DPF, total carbonyl compound emission decreased 15.7%, from 25.8 to 21.8 mg/kWh. The two highest carbonyls, formaldehyde and acetaldehyde, were reduced from 20.0 and 3.7 to 16.5 and 3.3 mg/kWh respectively. The specific reactivity(SR) with DPF was reduced from 6.68 to 6.64 mg/kWh. Total particle-phase PAH emissions decreased 66.4% with DPF compared to that without DPF. However, the Benzo[a]pyrene equivalent(BaPeq) with DPF had increased from 0.016 to 0.030 mg/kWh.Fluoranthene and Pyrene had the greatest decrease, 91.1% and 88.4% respectively. The increase of two- and three-ring PAHs with DPF indicates that the fuel-borne catalyst caused some gas-phase PAHs to adsorb on particles. The results of this study expand the knowledge of the effects of using a particulate filter and a Fe-based fuel-borne catalyst on diesel engine unregulated emissions. 相似文献
163.
Carbonyl emissions from heavy-duty diesel vehicle exhaust in China and the contribution to ozone formation potential 总被引:6,自引:0,他引:6
Fifteen heavy-duty diesel vehicles were tested on chassis dynamometer by using typical heavy duty driving cycle and fuel economy cycle. The air from the exhaust was sampled by 2,4- dinitrophenyhydrazine cartridge and 23 carbonyl compounds were analyzed by high performance liquid chromatography. The average emission factor of carbonyls was 97.2 mg/km, higher than that of light-duty diesel vehicles and gasoline-powered vehicles. Formaldehyde, acetaldehyde, acetone and propionaidehyde were the species with the highest emission factors. Main influencing factors for carbonyl emissions were vehicle type, average speed and regulated emission standard, and the impact of vehicle loading was not evident in this study. National emission of carbonyls from diesel vehicles exhaust was calculated for China, 2011, based on both vehicle miles traveled and fuel consumption. Carbonyl emission of diesel vehicle was estimated to be 45.8 Gg, and was comparable to gasolinepowered vehicles (58.4 Gg). The emissions of formaldehyde, acetaldehyde and acetone were 12.6, 6.9, 3.8 Gg, respectively. The ozone formation potential of carbonyls from diesel vehicles exhaust was 537 mg O3/km, higher than 497 mg O3/km of none-methane hydrocarbons emitted from diesel vehicles. 相似文献
164.
Yuguang Zhang Jing Cong Hui Lu Guangliang Li Yuanyuan Qu Xiujiang Su Jizhong Zhou Diqiang Li 《环境科学学报(英文版)》2014,26(8):1717-1724
Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units(OTUs). A significant single peak distribution pattern(P 0.05) between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased(P 0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship(P 0.01) with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure. 相似文献
165.
Huirong Lin Chengsong Ye Lu Lv Clark Renjun Zheng Shenghua Zhang Lei Zheng Yidong Zhao Xin Yu 《环境科学学报(英文版)》2014,26(8):1763-1768
A combined approach of physicochemical extraction and sulfur K-edge X-ray absorption near-edge structure(XANES) spectroscopy was applied to characterize the extracellular polymeric substances(EPS) of typical bacterial biofilms in this study. Physicochemical analysis showed variation of the contents of DNA,polysaccharide and protein in different fractions of EPS in different mediums. The sulfur K-edge XANES analysis yielded a variety of spectra.Spectral fitting of the XANES spectra utilizing a large set of model compounds showed that there was more reduced sulfur in both LB-EPS(loosely bound EPS) and TB-EPS(tightly bound EPS) of all the biofilms in LB medium than in R2 A medium. More oxidized sulfur was identified in LB-EPS than that in TB-EPS,suggesting different niches and physiological heterogeneity in the biofilms. Our results suggested that the sulfur K-edge XANES can be a useful tool to analyze the sulfur speciation in EPS of biofilms. 相似文献
166.
167.
垂直流人工湿地LDHs覆膜改性沸石基质强化除磷效果及其机制 总被引:6,自引:5,他引:1
采用碱性水热-共沉淀法,将6种金属化合物(CaCl2、ZnCl2、MgCl2、FeCl3、AlCl3、CoCl3)两两组合生成9种不同类型的层状双金属氢氧化物并覆膜于常用垂直流人工湿地沸石基质表面;利用分别填充原始沸石及9种LDHs覆膜改性沸石基质的模拟垂直流人工湿地小试系统进行除磷净化实验,并结合10种沸石基质的等温吸附实验结果,对LDHs覆膜改性沸石基质的强化除磷机制进行研究.结果表明,相对于原始沸石基质,9种不同组合方式生成的LDHs覆膜改性沸石基质除磷效果均有不同程度的提高;Zn2+参与合成的改性基质除磷效果优良,其中ZnFe-LDHs改性沸石基质对总磷、溶解性总磷及磷酸盐的平均去除率超过90%,其最大理论吸附量达到了原始沸石基质的3倍;LDHs覆膜改性沸石基质通过增加化学吸附容量、提高物理吸附能力达到强化除磷效果的目的. 相似文献
168.
建立了二氯甲烷液液萃取-气相色谱法同时测定地表水中17种有机氯农药的方法。标准曲线线性良好,17种化合物的相关系数R2均大于0.999。当取样量为200 mL时,方法检出限在0.015μg/L~0.062μg/L之间。以超纯水样品进行基质加标实验,重复测定6次的相对标准偏差为1.2%~6.2%,平均加标回收率为72.8%~93.5%。方法简单快捷,精密度良好,准确性高,适用于地表水中痕量有机氯农药的测定。 相似文献
169.
170.