Ionic imbalance due to hydrogen carbonate from Asian dust

In an attempt to identify the ionic imbalance, hydrogen carbonate, HCO₃⁻ (bicarbonate), was determined together with the commonly determined nine major ions because the imbalance was frequently encountered in the chemical analysis of samples with high pHs. Titration method was applied for the determination of the samples with pH higher than 5.6. These samples amounted to 102 of the 1536 samples collected in Hokkaido, Northern Japan, from April 1998 to December 2002. Of the 102 samples, 74 (Group A) showed an acceptable ion balance without including HCO₃⁻. In the other 28 (Group B), however, inclusion of HCO₃⁻ successfully improved the ion balance. These results suggested that hydrogen carbonate was a potential candidate for explaining the imbalance. The hydrogen carbonate concentrations showed a strong correlation with the corresponding non-sea salt calcium (nss-Ca²⁺) concentrations, which implied that hydrogen carbonate was derived from calcium carbonate particles incorporated into falling raindrops or cloud droplets. For Group A, the relationship between hydrogen carbonate and the nss-calcium ion concentration was very similar to that for commonly suspended particles in Hokkaido. On the other hand, Group B exhibited a stronger but significantly different correlation. To the samples of Group B, a back-trajectory analysis was applied to demonstrate that the samples were associated with aerosol travelling from Northern China or Mongolia, which indicated that alkaline aerosol affected the chemistry. In consideration of these findings, the current standard of the ion balance should be critically reviewed for modification in regard to the contribution of hydrogen carbonate not only in source areas but also in receptor areas of alkaline aerosol.     

北京市发展CNG汽车的条件与前景分析

北京市汽车排放污染物贡献率已达到：HC73.5％，CO63．4％，NOx46％。用CNG代替汽油作汽车燃料，可使CO减少97％、HC减少72％、NOx减少39％、CO2减少24％、SO2减少90％。建立CNG加气站和CNG汽车改装这两个CNG应用关键问题在技术上、经济上都是可行的。北京市CNG燃料来源有保障。北京市车辆都比较适合使用CNG气体燃料。北京有很强的CNG汽车产业科技力量。对北京市当前发展CNG汽车产业提出了一些建议。     

环境水体中痕量酚类化合物气相色谱-质谱联用测定法研究

建立了液-液萃取-气相色谱/质谱联用仪测定环境水体中痕量酚类化合物的方法。用乙酸乙酯萃取环境水中的痕量酚类化合物,加入萘-d8作为内标,利用气相色谱-质谱联用仪选择离子监测(SIM)的方式进行检测,内标法定量,定性、定量准确,线性响应良好,回归曲线的相关系数均>0.999,平均回收率在89.4%~104%之间,精密度好,相对标准偏差<7.4%;抗干扰能力强,检测灵敏度高,水样中最低检测浓度可达0.001mg/L,经实际样品测定完全能满足环境水体中痕量酚类化合物监测的要求。     

固相萃取-气相色谱法测定水中硝基苯类有机污染物的方法研究

建立了固相萃取、毛细柱气相色谱-电子捕获检测器定量分析水中硝基苯类化合物的分析方法。通过对固相萃取柱的选择、固相萃取条件(样品溶液的pH值、上样速度、上样体积、洗脱液选择及配比)的优化,得出了最佳实验条件。穿透体积可达1.5L,回收率在80%~105%,最小检出浓度在0.00037~0.072μg/L之间,均大大低于GB13194-91的规定。相对标准偏差在0.7%~5.3%之间。该方法准确、简单,重现性好、回收率高,污染小。     

气相和颗粒物中邻苯二甲酸酯的采样与检测技术

对邻苯二甲酸酯的性质及其在环境空气中的存在状态、样品采集技术与分析方法进行了综述,侧重介绍了样品的采集、净化、采样效率和采样与分析全过程的质量控制。     

助催化无汞盐快速测定水中化学需氧量

在ψ（Ｈ２ＳＯ４）＝５６％硫酸介质，重铬酸钾的氧化体系中，以钼权铵，硫酸铝钾为助催化剂，可减少量化剂硫酸银的用量，消解１５ｍｉｎ即可测定水中化学需氧量，用硝酸银溶液代替硫酸汞去除水氯离子，避免了汞盐的污染，工业废水回收率在９７％～１０１％之间，有较好的准确度。     

环境中萘和甲基萘的气相色谱测定

针对发生的甲基萘油车泄漏事故进行了水样和空气样品中萘和甲基萘的测定，水样中直接进样，对空气样品则以甲醇为吸收液吸收，富集，氢火焰毛细管色谱法测定。     

用液相催化法和脱硫除尘器脱除烟气中SO_2

在由旋风水膜和两块旋流塔板组成的处理气量为７５０ｍ￣３／ｈ的二级脱硫除尘器中，进行了用含催化剂Ｍｎ￣（２＋）的水溶液吸收ＳＯ_２的扩大试验。结果表明，在确定的条件下，脱硫率达到７３％，板效率为０．２５～０．２８。在同一设备中同时完成除尘与脱硫过程，设备投资少；以水为吸收剂，运行费用低；中性条件下吸收，长期运转不结垢，可靠性高。     

毛细管气相色谱法分析1,3—丁二烯中炔烃杂质含量

介绍了一种毛细管毛相谱法测定１，３－丁烯中炔烃质含量的新试验方法，该方法以氮气为载气，采用氢火焰离子化检测器，样品经分离后，采用外标法定量，操作简便，准确。该方法还可用于１，３－丁二烯纯度分析 。     

燃煤锅炉氨法烟气脱硫

通过氨法脱硫工艺在75t燃煤锅炉烟气脱硫工程中的运用,阐述了氨法脱硫的原理及工业条件,并对运行指标及处理效果进行分析。