顶空-毛细管柱气相色谱法测定气样中甲醇

对自动顶空进样器与气相色谱法联用技术测定环境空气和废气中甲醇的方法进行了研究。结果表明：当样品加入4g氯化钠,顶空平衡温度为80℃,平衡时间为20min,用HP—FFAP毛细管柱分离,氢火焰离子化检测器检测时,得到甲醇标准曲线方程为y=23415x＋237．2,相关系数（R）0．9994;检出限为0．002mg／m2,相对标准偏差（n=6）为0．5％,加标回收率为98．9％。该方法简单、灵敏、分离度好、检出限低。     

Nano-TiO2 enhances the toxicity of copper in natural water to Daphnia magna

The acute toxicity of engineered nanoparticles (NPs) in aquatic environments at high concentrations has been well-established. This study demonstrates that, at a concentration generally considered to be safe in the environment, nano-TiO₂ remarkably enhanced the toxicity of copper to Daphnia magna by increasing the copper bioaccumulation. Specifically, at 2 mg L⁻¹ nano-TiO₂, the (LC₅₀) of Cu²⁺ concentration observed to kill half the population, decreased from 111 μg L⁻¹ to 42 μg L⁻¹. Correspondingly, the level of metallothionein decreased from 135 μg g⁻¹ wet weight to 99 μg g⁻¹ wet weight at a Cu²⁺ level of 100 μg L⁻¹. The copper was found to be adsorbed onto the nano-TiO₂, and ingested and accumulated in the animals, thereby causing toxic injury. The nano-TiO₂ may compete for free copper ions with sulfhydryl groups, causing the inhibition of the detoxification by metallothioneins.     

潞城市大气PM_（10）中化学元素分布特征

利用ICP-AES分析了潞城市采暖期和非采暖期4个不同功能区PM10样品中16种化学元素,对不同元素的时空分布特征进行了研究,并采用富集因子和主成分分析初步研究了潞城市PM10中元素的主要来源。结果表明,潞城市PM10中重金属污染较为严重,且各元素在采暖期的平均浓度均明显高于非采暖期。PM10中Ca、V、Cr、As、Ni、Mn、Cu、Zn、Al和Pb的富集因子EF〉10,主要来源于人为污染;而Na、Mg、Si、Fe和K的EF〈10,除部分来自人为活动外,主要来自土壤风沙等自然来源。主成分分析结果显示,潞城市PM10中元素的主要来源按贡献率大小依次为：煤烟尘和工业粉尘50.39%,自然源34.37%和机动车尾气15.24%。     

新型改性聚丙烯酰胺的合成及对污泥调理效果的研究

采用原位聚合法,在聚丙烯酰胺的聚合过程中引入金属离子进行改性,合成了一种新型改性聚丙烯酰胺.通过正交实验确定了改性聚丙烯酰胺的最佳合成条件.红外图谱显示,该聚丙烯酰胺是一种具有特殊结构的有机高分子化合物.以污泥脱水率和污泥比阻为考察指标,研究了改性聚丙烯酰胺对污水处理厂剩余活性污泥脱水性能的影响,结果表明,在每1000...     

Enhancement of chlorophenol sorption on soil by geophagous earthworms (Metaphire guillelmi)

Earthworms are the dominant soil biomass of many terrestrial ecosystems and markedly influence the physico-chemical and biological properties of soil; however, little is known about the effects of earthworm activities on the environmental behavior of micropollutants in soil. We studied the sorption and desorption of 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol on geophagous earthworm (anecic Metaphire guillelmi) casts of various aging times and on the parent soil. The casts were characteristic of lower pH and higher content of fine particles (silt and clay) than the parent soil. The sorption of the chlorophenols on the soil and casts were well fitted to linear isotherms, with sorption capacity in the order of pentachlorophenol > 2,4-dichlorophenol > 2,4,6-trichlorophenol. The sorption on the cast with different aging time was quite similar and was higher than on the parent soil. The sorption on the soil did not change between pH 7.07 of the soil and pH 6.76 of the casts. The desorption hysteresis of the chlorophenols on the soil and casts was compound specific and 2,4,6-trichlorophenol showed the highest hysteresis. The higher sorption capacity of the casts was not owing to the lowered pH of the casts, but mainly to the higher fine particles in the casts and the possible changes of nature of the soil organic matter through the earthworm gut passage. Our results indicate that geophagous earthworms may change sorption behavior and thus the bioavailability and transport of chlorophenols in soil. Earthworm effects should be considered when evaluating the environmental behavior and risk of organic pollutants in the ecosystems where earthworms are abundant.     

河北省海域承载力多层次模糊综合评价

借鉴有关承载力的研究成果,利用多层次模糊综合评判法对河北省海域承载力进行了评价分析。结果表明:1996—2006年间河北省近海海域承载力一直处于超载状态,但承载状况总体趋于好转;人口和环境污染的加剧、环境治理能力和科技发展水平缓慢、资源供给能力不足是导致河北省海域承载力超载的主要因素。基于此提出了改善河北省海域承载状况的对策建议。     

城镇圩区排涝模数计算方法及其与河道调蓄库容关系研究

农业圩区原有的排涝模数计算方法已不适用于城镇圩区.针对城镇圩区的排涝特殊性,通过分析排涝计算的原理,充分考虑圩区内河道的调蓄能力,得到适应城镇圩区排涝计算的方法.以南京市江宁区为例,对城镇圩区的排涝模数进行计算,得到排涝模数与调蓄库容之间的定量关系.     

了解外企文化,面试顺利闯关

作为人类社会中的一个重要组成部分,文化无时无刻不在影响和制约着人们的社会行为。外资企业因其所在的不同文化,形成了独特的企业文化与用人理念。真正了解外企文化及其价值观,才能在面试中充分发挥并展示出企业所需要的素养与品质,最终轻松进入职场。     

Performance of Gd-doped Ti-based Sb-SnO2 anodes for electrochemical destruction of phenol

The performance of electrodes for the electro-catalytic decomposition of a model pollutant (phenol) was enhanced using Gd-doped Ti/SnO(2)-Sb electrodes prepared by a thermal deposition method. Phenol degradation followed first-order rate kinetics, with the maximum rate achieved using a 2% Gd doping level (molar ratio based on Gd:Sn) for tests conducted over a doping range of 1-10%. The first-order rate constant with 2% Gd was 0.044 min(-1), versus 0.026 min(-1) obtained with the control (plain Ti/SnO(2)-Sb). TOC removal and UV scans revealed that different intermediates were produced for different Gd contents, and that destruction efficiencies of these intermediates also varied with Gd doping levels of 1-5%. Electrodes were characterized by scanning electron microscopy, X-ray diffraction, electron dispersive spectrometry, and X-ray photon-electron spectroscopy. It is suggested that the state of specific active sites on the electrode surface and the oxygen transfer activity at the electrode/electrolyte interface affect the performance of anodes with different compositions.     

Enhanced photocatalytic activities of silicon nanowires/graphene oxide nanocomposite: Effect of etching parameters

Homogeneous and vertically aligned silicon nanowires (SiNWs) were successfully fabricated using silver assisted chemical etching technique. The prepared samples were characterized using scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Photocatalytic degradation properties of graphene oxide (GO) modified SiNWs have been investigated. We found that the SiNWs morphology depends on etching time and etchant composition. The SiNWs length could be tuned from 1 to 42 µm, respectively when varying the etching time from 5 to 30 min. The etchant concentration was found to accelerate the etching process; doubling the concentrations increases the length of the SiNWs by a factor of two for fixed etching time. Changes in bundle morphology were also studied as function of etching parameters. The SiNWs diameter was found to be independent of etching time or etchant composition while the size of the SiNWs bundle increases with increasing etching time and etchant concentration. The addition of GO was found to improve significantly the photocatalytic activity of SiNWs. A strong correlation between etching parameters and photocatalysis efficiency has been observed, mainly for SiNWs prepared at optimum etching time and etchant concentrations of 10 min and 4:1:8. A degradation of 92% was obtained which further improved to 96% by addition of hydrogen peroxide. Only degradation efficiency of 16% and 31% has been observed for bare Si and GO/bare Si samples respectively. The obtained results demonstrate that the developed SiNWs/GO composite exhibits excellent photocatalytic performance and could be used as potential platform for the degradation of organic pollutants.