Gaseous emissions from compressed natural gas buses in urban road and highway tests in China

The natural gas vehicle market is rapidly developing throughout the world, and the majority of such vehicles operate on compressed natural gas(CNG). However, most studies on the emission characteristics of CNG vehicles rely on laboratory chassis dynamometer measurements, which do not accurately represent actual road driving conditions. To further investigate the emission characteristics of CNG vehicles, two CNG city buses and two CNG coaches were tested on public urban roads and highway sections. Our results show that when speeds of 0–10 km/hr were increased to 10–20 km/hr, the CO_2, CO, nitrogen oxide(NO_x), and total hydrocarbon(THC) emission factors decreased by(71.6 ± 4.3)%,(65.6 ± 9.5)%,(64.9 ± 9.2)% and(67.8 ± 0.3)%, respectively. In this study, The Beijing city buses with stricter emission standards(Euro Ⅳ) did not have lower emission factors than the Chongqing coaches with Euro Ⅱ emission standards. Both the higher emission factors at 0–10 km/hr speeds and the higher percentage of driving in the low-speed regime during the entire road cycle may have contributed to the higher CO_2 and CO emission factors of these city buses. Additionally, compared with the emission factors produced in the urban road tests, the CO emission factors of the CNG buses in highway tests decreased the most(by 83.2%), followed by the THC emission factors, which decreased by 67.1%.     

城市污水管网污染物沉积与冲刷释放规律研究

为明确城市污水管网中污染物沉积、冲刷释放及微生物降解作用对有机物去除的贡献,以管网中城市污水为研究对象,通过建立有沉积与无沉积的模拟管道,在首次冲刷的理论基础上得到管道污染物沉积释放计算模型,进而研究了不同流量下有机污染物的沉积与冲刷释放规律,并对不同流量下进出水的粒径分布及颗粒组成进行分析。结果表明,在管道6 h水力循环条件下,当流速为0.32 m/s时,污水中有机物变化以沉积贡献为主;当流速增加为管网最小设计流速0.6 m/s时,污染物沉积现象得到显著改善,冲刷释放效应增强;当流速进一步增加为0.9 m/s时,冲刷释放成为主要作用,生物降解作用微弱。     

盐度水平对不同盐渍化程度土壤氧化亚氮排放的影响

选取内蒙古河套灌区3种不同盐渍化程度土壤(盐土、重度盐渍化土壤和轻度盐渍化土壤),采用室内培养方法,用不同浓度KCl溶液调节不同盐渍化程度土壤盐含量分别为原土壤盐含量(对照)的2倍和3倍,研究盐分对不同盐渍化程度土壤氧化亚氮(N_2O)排放的影响.结果表明,盐分含量显著影响不同盐渍化程度土壤N_2O排放.无外源盐分加入时,不同盐碱程度土壤中盐土N_2O排放量最高,重度盐渍化土壤次之,轻度盐渍化土壤最低.外源盐加入后,随盐度梯度升高,与其对照相比,盐土N_2O排放量降低;重度盐渍化土壤N_2O排放量呈现先增加后降低趋势;轻度盐渍化土壤N_2O排放量升高.与其对照相比,土壤的盐分含量增加2倍时,盐土N_2O排放量减少90%;轻度盐渍化土壤N_2O排放量增加9倍.外源盐加入不同盐渍化程度土壤对N_2O排放的影响程度取决于土壤培养前后铵态氮含量差值,加入外源盐后,N_2O累积排放变化量的94.6%由土壤NH_4~+-N含量差值解释(R2=0.95,p0.01).     

The effect of organic solvent washing on the structure of hydrochar-based dissolved organic matters and its potential environmental toxicity

Environmental Science and Pollution Research - With the increased interest in the practical use of hydrochar, concerns about the possible environmental biotoxicity of hydrochar and its released...     

Regeneration of nano-ZnO photocatalyst by the means of soft-mechanochemical ion exchange method

Nano-crystalline ZnO particles synthesized via an ion exchange method were used in a methyl-orange photocatalytic degradation process. An ion exchange resin mixed bed system was used in the suspension for separation of nano-ZnO and methyl-orange after photocatalysis reaction. Ion exchange resin, photocatalyst and water were mixed evenly by airflow. Nano-ZnO photocatalyst and soluble carboxyl zinc were gathered in the soft-mechanochemical process simultaneously. Ion exchange reaction ZnO photocatalyst and counterion transfer process on resin were all improved. Byproducts and other inorganic ions were transfered into resin phase. Nano-ZnO photocatalyst can be regenerated and reused.     

废弃地的景观与生态恢复研究

废弃地是一种对生态环境造成重大破坏并且造成土地资源浪费的土地类型,如何进行合理的改造以形成可持续的土地利用模式是十分棘手的问题.利用新乡市北站区世利生态园的废弃地改造项目进行了废弃地"变废为宝"的探索,对合理进行废弃地的景观与生态恢复进行了较为深入的研究.通过对该废弃地现状的分析,得出对其进行合理的景观与生态恢复迫在眉睫.依据景观设计与生态恢复的理论、方法与原则,提出了景观恢复与生态恢复的具体措施,该措施可满足废弃地在自然生态、景观、经济和社会发展等方面可持续发展的要求.      

百花湖入库河流麦西河河口消落带土壤磷形态及其分布特征研究

应用磷形态标准测定方法（SMT）对百花湖（水库）入库河流麦西河河口消落带土壤不同形态的磷进行了分级测定,分析了各形态磷及与有机质、pH之间的相关性。结果表明：消落带A区(岸边土壤)总磷含量平均为1 298.8 mg/kg,B区(交界面土壤)平均为1 1712 mg/kg,C区(淹没区土壤)平均为1 0762 mg/kg。各种形态的磷在消落带分布特点不同：（1）各点OP含量A区>B区>C区,OP/TP的平均值为592%、607%、633%;（2）各点IP以Fe/Al P为主,消落带A区Fe/Al P占无机磷的比例平均为789%,B区为642%,而C区则为546%;（3）Ca P含量C区（1017 mg/kg）>B区（849 mg/kg）>A区（621 mg/kg）;（4）消落带A区土壤中活性磷组份（OP+Fe/Al P）占TP百分数为738%,B区为744%,C区为771%。消落带土壤活性磷组份较高,在适宜的条件下容易引起水体的二次污染,加快水体富营养化的进程     

活性炭复合床层对动活性的影响试验

本文通过对KZ1床层、KZ2床层、KZ1和KZ2复合床层在不同床层厚度条件下,对氯化氰蒸气的动活性进行对比试验,并对试验结果进行分析,得出了后者并非前两者之和,而有了大幅提高的结论。     

煤化工煤焦油逸出废气回收利用技术研究

通过对河北省秦皇岛市耀华玻璃工业园有限公司地下300m,储油罐煤焦油逸出废油气进行实验室模拟实验,现场实际工程设计、制造、安装、调试、检验等实践研究,采用“冷凝＋自激吸收器＋吸收＋活性炭吸附”油气处理回收技术,并独创了自激吸收器新技术,处理后的煤焦油逸出废气完全达到了国家《炼焦化学工业污染物排放标准》（GB16171—2012）的相关要求。