表面活性剂对多壁碳纳米管吸附Pb~(2+)的影响

多壁碳纳米管(MWNT)在吸附有毒气体和重金属离子方面具有极高的应用价值.针对MWNT对水溶液中Pb2+的净化吸附进行了研究,从吸附量,吸附速率、动力学角度考察了表面活性剂、Pb2+浓度对MWNT吸附Pb2+的影响.结果表明,司班-60、吐温-20、阿拉伯树胶等表面活性剂的加入,促进了MWNT在溶液中的分散,导致在Pb2+摩尔浓度为3～18 mmol/L的Lang-muir和Freundlich等温吸附方程中的吸附常数(K)变大,使得MWNT对Pb2+的吸附速率和平衡吸附量都得到提高;随着溶液中Pb2+浓度的增大,MWNT对其吸附量渐至饱和,随后由于Pb2+的位阻作用.吸附量下降;在这3种表面活性剂中,由于司班-60具有相对较小的分子量,其分散的MWNT在Pb2+摩尔浓度为14 mmol/L时,吸附量最大,为230 mg/g.     

GC/MS法测定润滑油基础油中多环芳烃

对润滑油基础油中多环芳烃的气相色谱/质谱(GC/MS)测定方法进行了研究,探讨了样品的提取,固相萃取柱净化等前处理方法,同时也对仪器测定条件进行了优化.结果表明,在检测润滑油基础油中多环芳烃时,经优化的GC/MS法的加标回收率和精密度均达到较满意的水平.     

土壤重金属的植物污染化学研究进展

针对中国土壤重金属污染加剧的趋势,为改善土壤环境质量和保障农产品安全,提出了土壤重金属的植物污染化学研究领域.结合多年的研究工作,从土壤重金属的植物根际化学行为、土壤重金属的植物吸收与解毒机制和重金属污染土壤的植物-微生物交互作用等方面简要阐述了土壤-植物系统中重金属的分布、存在形态、迁移转化、累积及生物学效应和控制规律的研究进展,并对将来的植物污染化学理论研究提出了展望.     

Continuous measurement of peroxyacetyl nitrate (PAN) in suburban and remote areas of western China

Knowledge on atmospheric abundance of peroxyacetyl nitrate (PAN) is important in assessing the severity of photochemical pollution, and for understanding chemical transformation of reactive odd nitrogen and its impact on the budget of tropospheric ozone (O₃). In summer 2006, continuous measurements of PAN were made using an automatic GC–ECD analyzer with an on-line calibrator at a suburban site of Lanzhou (LZ) and a remote site of Mt. Waliguan (WLG) in western China, with concurrent measurements of O₃, total reactive nitrogen (NO_y) and carbon monoxide (CO). At LZ, several photochemical episodes were observed during the study, and the average mixing ratio of PAN (plus or minus standard deviation) was 0.76 (±0.89) ppbv with the maximum value of 9.13 ppbv, compared to an average value of 0.44 (±0.16) ppbv at remote WLG. The PAN mixing ratios in LZ exhibited strong diurnal variations with a maximum at noon, while enhanced concentrations of PAN were observed in the evening and a minimum in the afternoon at WLG. The daily O₃ and PAN concentration maxima showed a strong correlation (r² = 0.91) in LZ, with a regression slope (PAN/O₃) of 0.091 ppbv ppbv^?1. At WLG, six well-identified pollution plumes (lasting 2–8 h) were observed with elevated concentrations of PAN (and other trace gases), and analysis of backward particle release simulation shows that the high-PAN events at WLG were mostly associated with the transport of air masses that had passed over LZ.     

Polychlorinated biphenyls and organochlorine pesticides in various bird species from northern China

Little data are available on organochlorine contamination in Chinese terrestrial birds of prey. This study examined the presence of PCBs, DDTs and other organochlorine pesticides in various raptors from northern China. DDE exhibited the highest concentrations among targeted compounds. Greatest levels (23.5-1020 mg/kg lipid weight) were observed in Eurasian sparrowhawks. This may be due to their stopover in southeastern China, where high DDT and dicofol applications have been documented. Residential kestrels exhibited much lower DDE, but similar PCB and HCH concentrations. ΣTEQs and PCB-126/-77 concentration ratios exhibited significant positive correlations with ΣPCB concentrations, respectively. Similar results were also demonstrated by a meta-analysis of previously published data across avian species. Possible hepatic sequestration of coplanar PCB-77, -126, -169 and -118 was observed as liver TEQs increased in Eurasian sparrowhawks. These observations may indicate an induction of CYP1A enzymes, as a result of elevated contamination in some species.     

PM10-PM2.5冲击采样器的研制与开发

在颗粒物研究中,分级采样是一种常用的监测方法,而冲击采样器是颗粒物分级采样的重要仪器.根据斯托克斯数,对PM10-PM2.5冲击采样器设计参数进行了详细分析,并对PM10-PM2.5的捕集效率特征进行了分析.结果表明,PM10-PM2.5冲击采样器具备理想的PM10和PM2.5捕集效率,PM10冲击采样器、PM2.5冲击采样器切割粒径分别为9.94、2.43μm,均在其允许误差范围内.     

Single particle mass spectrometry of oxalic acid in ambient aerosols in Shanghai: Mixing state and formation mechanism

Oxalic acid in individual aerosol particles was measured using single particle aerosol time-of-flight mass spectrometry (ATOFMS) in the summer of 2007 in Shanghai, China. Oxalate was found in 3.4% of total particles with diameters in the range of 0.2 – 2.0 μm. Size, chemical composition and hourly temporal counts of single particles that contained oxalic acid were measured. The predominant types of oxalate-containing particles were characterized to distinguish the primary and secondary sources of oxalic acid. Biomass burning was revealed as a major primary source of oxalic acid which contributed more than 20% of the oxalate-containing particles. Evidences for two different formation pathways of oxalic acid were observed in our experiment. The number fraction of oxalate-containing particles correlated with that of sulfate particles and the changes of air parcel backward trajectories, suggesting that in-cloud processing played important roles in oxalic acid formation. The diurnal patterns of dust and sea salt particle counts fitted well with the ambient relative humidity variation, suggesting that heterogeneous reactions occurring in hydrated/deliquesced aerosols also contributed to the production of oxalic acid.     

An important pathway for ozonolysis of alpha-pinene and beta-pinene in aqueous phase and its atmospheric implications

The aqueous ozonolysis of α-pinene and β-pinene was conducted under simulated tropospheric conditions at different pHs and temperatures. Three kinds of products, peroxides, carbonyl compounds, and organic acids, were well characterized, and the detection of these products provides effective evidence for understanding the atmospheric aqueous reaction pathway. We have two interesting findings: (1) the unexpected formation of methacrolein (MACR), with a yield of ～40%, in the α-pinene–O₃ aqueous reaction indicates a potentially new SOA formation pathway, because MACR is one of the important precursors of SOA; and (2) the surprisingly high yields of H₂O₂, ～60% for the α-pinene–O₃ reaction and ～100% for the β-pinene–O₃ reaction, indicates that H₂O₂ can be a significant contributor to the origin and transformation of oxidants in the atmosphere, especially in the humid regions. Moreover, we have determined the rate constant for aqueous reaction between MACR and H₂O₂ in pH 2 to 7 and obtained its upper limit as 0.13 M L^?1 s^?1. A mechanism concerning the formation of the species mentioned above is proposed, and it differs from that in the gas-phase reaction. We suggest that water plays a key role in the mechanism, by participating in the reactions as a direct reactant and by removing the excess energy of intermediates formed in the reactions.     

新型悬浮填料澄清池中填料对澄清作用的影响初探

为考察可取代传统二沉池的新型悬浮填料澄清池技术的原理及关键参数,小试试验研究了填料对新型悬浮填料澄清池固液分离过程中附着污泥形成及其絮凝性能的影响,并对填料在澄清中的作用机理进行了探讨。结果表明,当泥水界面上升至填料区后,可以形成较悬浮污泥更加致密稳定的附着污泥区,并形成孔道流,强化了对混合液中污泥颗粒的絮凝效果;填料区可以捕捉去除从悬浮污泥区中“逃逸”的微小污泥絮体,并降低出水浊度,有效地保证了出水水质的稳定性。填料的存在发挥了强大的整流作用,降低了雷诺数Re,提高了弗汝德数Fr,从而改善了污泥絮凝的水力条件,提高了澄清能力。     

土壤中零价铁还原3-氯硝基苯的作用

利用零价铁在常温常压下对土壤中的3-氯硝基苯的还原,对反应物和产物随时间的变化及反应的各个影响因素进行了研究。实验结果表明,零价铁能够有效地将3-氯硝基苯还原为3-氯苯胺,反应过程中没有检测到脱氯产物。其反应速率随铁粉用量、反应体系含水量的增加以及反应温度的升高而升高,随土壤初始pH值的升高而降低。在土壤中3-氯硝基苯含量约为2.5×10^-6 mol/g,铁粉使用量为25 mg/g,反应体系中含水量为0.75 mL/g,pH值为6.8时,在恒温生化培养箱(25±1)℃反应5 h后,3-氯硝基苯的还原率达到92.75％。