我国典型季风海洋型冰川积累区冰雪剖面的环境记录

运用多种方法,对白水1号冰川积累区冰雪剖面的主要阴、阳离子和δ18O的环境意义分析表明,受强烈淋溶作用影响,离子和δ18O的季节变化不明显,剖面离子浓度显著低于雪坑,离子流失量较大。NH4+年际变化最为显著,与丽江降水表现出相同的变化趋势,Mg2+和Ca2+浓度与冰雪剖面净积累量呈反向变化。分析表明,阴离子主要是湿沉降产物,阳离子主要是干沉降产物。该剖面所反映的13年δ18O比率变化介于-11.8‰～-14.6‰。冰雪剖面中δ18O与西南季风指数、冰雪剖面积累量、丽江降水和丽江气温呈反向变化,表现出显著的"降水量效应"。     

发展清洁化学 保护生态环境

传统的化学工业在为人类社会发展提供强大物质基础的同时,由于工艺和原料的原因,也不可避免带来了严重的环境污染问题,对生态环境构成严重威胁。清洁化学的出现,为我们解决环境污染问题带来了新的希望。     

绿色化学与可持续发展

绿色化学是一门从源头上阻止污染的化学,它吸收了传统化学化工、环境、物理、生物、材料和信息等学科的最新理论和技术,代表了化学化工科学理念的重大变革,具有可持续发展的意义。本文介绍了绿色化学的一般概念及绿色化学与环境保护的关系,从主要研究内容及发展现状和趋势等方面阐明了绿色化学是可持续发展的必由之路。     

有机磷农药对海洋扁藻毒性构效关系的密度泛涵理论研究

采用密度泛函理论方法,在B3LYP/6-311G**水平上,计算了11个有机磷农药化合物的结构参数,将结构参数作为理论描述符,导出了有机磷类化合物的分子结构参数与2种盐度(S=20,S=30)下扁藻毒性(-lgEC50)的定量关系式(式(3)和(6)),并用交叉验证法验证,相关系数R分别为0.923 2和0.893 3,交叉验证相关系数q2分别为0.527 0和0.540 5.在此基础上,预测了11种有机磷农药的毒性.研究表明,所得预测方程有较好的稳定性和较强的预测能力.可用于有机磷化合物的-lgEC50预测.     

核桃果皮基活性炭对苯酚吸附的热力学研究

吸附法因具有处理设备简单、无二次污染等优点广泛应用于废水处理中.以核桃果皮基活性炭为吸附剂,研究其对苯酚吸附的热力学性质.结果表明,温度对吸附无显著影响,在20～60℃范围内,随温度升高,吸附量略有减小;苯酚溶液在酸性至中性条件下的吸附去除率较高.吸附符合经典的Langmuir与Freundlich等温方程,并存在吸附剂和吸附质浓度效应,Langmuir与Freundlich等温方程参数不确定为常数,而是随吸附质质量浓度ρo和吸附剂质量浓度W0变化而变化.研究表明,核桃果皮基活性炭能高效、快速地吸附去除苯酚,是一种有应用前景的净水材料.     

Is there a silver lining? Aggregation and photo-transformation of silver nanoparticles in environmental waters

Is the aggregation of silver nanoparticles in environmental waters a silver lining? The answer is not simple. Clearly, however, the aggregation and photo-transformation of AgNPs are complicated and could be more significant than previously thought. The difference in the water chemistry that controls the aggregation and photo-transformation of AgNPs results in the varying behavior and fate of AgNPs among different water bodies.     

1959-2008年乌鲁木齐河源1号冰川融水径流变化及其原因

采用数理统计、 Morlet小波分析和Mann-Kendall突变检验对乌鲁木齐河源1号冰川1959-2008年径流序列进行分析,揭示了冰川融水径流的变化趋势、 周期特征和突变特性,并对径流与气候、 冰川变化关系进行了探讨。结果表明:乌鲁木齐河源1号冰川近50 a来径流增加趋势显著,特别是在1993年发生突变后,平均径流较1993年前增加了69.4%。径流序列第一主周期为15 a,第二主周期为6 a。在13~16 a时间尺度上看,1号冰川融水径流在未来的几年将继续保持偏多趋势,但是从5~7 a和超长期时间尺度上看则相反。冰川融水径流与冰川物质平衡、 年均气温、 消融期气温及年降水量存在良好的瞬时响应关系,其中消融期气温的振动对冰川融水径流振动能量贡献最大,在气温超过2 ℃时,径流将加速增长。物质平衡变化100 mm可引起河流径流变化22.9×10⁴ m³,1号冰川过去50 a累积物质平衡为-13 693 mm,相当于额外补给河流径流量3 135.7×10⁴ m³,约是年径流量的16.1倍。     

Numerical studies on minimum ignition energies in methane/air and iso-octane/air mixtures

In this study, the dependence of minimum ignition energies (MIE) on ignition geometry, ignition source radius and mixture composition is investigated numerically for methane/air and iso-octane/air mixtures. Methane and iso-octane are both important hydrocarbon fuels, but differ strongly with respect to their Lewis numbers. Lean iso-octane air mixtures have particularly large Lewis numbers. The results show that within the flammability limits, the MIE for both mixtures stays almost constant, and increases rapidly at the limits. The MIEs for both fuels are also similar within the flammability limits. Furthermore, the MIEs of iso-octane/air mixtures with a small spherical ignition source increase rapidly for lean mixtures. Here the Lewis number is above unity, and thus, the flame may quench because of flame curvature effects. The observations show a distinct difference between ignition and flame propagation for iso-octane. The minimum energy required for initiating a successful flame propagation can be considerably higher than that required for initiating an ignition in the ignition volume. For iso-octane with a small spherical ignition source, this effect was observed at all equivalence ratios. For iso-octane with cylindrical ignition sources, the phenomenon appeared at lower equivalence ratios only, where the mixture's Lewis number is large. For methane fuel, the effect was negligible. The results highlight the significance of molecular transport properties on the decision whether or not an ignitable mixture can evolve into a propagating flame.     

Intensification of adsorption process by using the pyrolytic char from waste tires to remove chromium(Ⅵ) from wastewater

Pyrolysis has the potential of transforming waste into valuable recyclable products. Pyrolytic char(PC) is one of the most important products from the pyrolysis of used tires. One of the most significant applications for pyrolytic char recovered is used for the removal of Cr(Ⅵ) in the wastewater effluent to control waste by waste. The surface chemistry properties of surface element distribution / concentration and chemical structure were examined for the pyrolytic char and the commercial activated carbon(CAC) respectively. The results showed that surfaces of PC possesses a large amount of ester and hydrocarbon graft, whereas there are mainly carbon functional components of C-OH, C=O and COOH on the surface of CAC. Therefore the surface electronegativity of PC is lower than that of CAC in the water. The repulsive interactions between the surfaces of PC and the negatively charged Cr(Ⅵ) ion are weaker than that of CAC, which results in an intensification of the adsorption process by the utilization of PC. The adsorption isotherms of Cr(Ⅵ) ion on the two kinds of carbons were determined experimentally. The larger adsorption amount on the PC in the case of Cr(Ⅵ) may be attributed mainly to its special surface micro-chemical environment. The mechanism of the removal Cr(Ⅵ) from aqueous solution was assumed to be the integration of adsorption and redox reaction. The adsorption was the rate-controlled step for Cr(Ⅵ) removal. The adsorption of Cr(Ⅵ) has been identified as pseudo-second- order kinetics. The rate constants of adsorption have been evaluated.     

凉水河流域地下水水化学特征和时空变化规律

北京凉水河流域的同位素和水化学特征分析表明:1)地下水水质在100m以浅相对较差,但到2017年为止,水质保持稳定.2)浅层地下水与平原区河水同位素相对富集,且落在同一条蒸发线上;但整体上河水与浅层地下水水化学类型不同,据此推断山前冲洪积扇河水入渗是区域地下水补给的重要来源,下游地下水主要受到侧向径流影响.3)同位素平...