Identifying influencing factors on paved roads silt loading

The factors that influence the increase or decrease of silt loadings on paved roadways have not been fully quantitatively investigated. They were identified in this study based on the quarterly silt loading sampling data collected from 20 sites by the Clark County Department of Air Quality and Environmental Management in Southern Nevada for the period from 2000 to 2003. The silt loading and associated data collected over these years at one sampling site may inherently possess site-specific characteristics that can be better incorporated by using panel data models. The factors that are identified as significant are the presence of curbs and gutters, shoulder type, pavement conditions, and the presence of construction activities in the vicinity of roadways. The presence of curbs and gutters, stabilized shoulders, and good pavement conditions would result in decreased silt loadings. Conversely, the presence of construction activities within the immediate vicinity of sampled areas would result in increases of silt loadings on the roadway surfaces. Based on the analysis of the results, it was recommended that constructing curbs, gutters and stabilized shoulders, preventing or reducing construction track-out from construction activity, and improving pavement conditions be the preferred control measures to reduce silt loading on paved roadways.     

高度分散TiO2催化超声降解乙基紫及与悬浮TiO2催化活性的比较

采用输出功率为50 W,频率为40 kHz的超声波作为激发源激发TiO2,比较了分散和悬浮2种不同形态TiO2存在时超声降解乙基紫的情况.结果表明,在高度分散TiO2存在的条件下,超声降解乙基紫的效果要远远好于悬浮TiO2,超声照射40 min降解率达到78.45%,而在悬浮TiO2存在下降解率只有27.12%,在单纯超声波作用下同样时间内降解率只有10%.另外还研究了不同因素包括:反应时间、初始浓度、催化剂加入量、超声功率和温度等对TiO2催化超声降解乙基紫反应的影响,讨论了TiO2催化超声降解乙基紫可能的反应机理.     

Effect of SiO2 addition on NH4HSO4 decomposition and SO2 poisoning over V2O5–MoO3/TiO2–CeO2 catalyst

The deposition of NH₄HSO₄ and the poisoning effect of SO₂ on SCR catalyst are the main obstacles that restrict the industrial application of CeO₂-doped SCR catalysts. In this work, deposited NH₄HSO₄ decomposition behavior and SO₂ poisoning over V₂O₅–MoO₃/TiO₂ catalysts modified with CeO₂ and SiO₂ were investigated. By the means of characterization analysis, it was found that the addition of SiO₂ into VMo/Ti–Ce had an impact on the interaction existed between catalyst surface atoms and NH₄HSO₄. Temperature-programmed methods and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments indicated that the doping of SiO₂ promoted the decomposition of deposited NH₄HSO₄ on VMo/Ti–Ce catalyst surface by reducing the thermal stability of NH₄HSO₄ and enhancing the NH₄HSO₄ reactivity with NO in low temperature. And this improvement may be the reason for the better catalytic activity than VMo/Ti–Ce in the case of NH₄HSO₄ deposition. Accompanied with cerium sulfate species generated over catalyst surface, the conversion of SO₂ to SO₃ was inhibited in SiCe mixed catalyst. The addition of SiO₂ could promote the decomposition of cerium sulfate, which may be a potential strategy to enhance the resistance of SO₂ poisoning over CeO₂-modifed catalysts.     

垃圾渗滤液有机组分和氨氮在孔隙介质中的迁移特征

通过室内土柱淋滤模拟实验研究了垃圾渗滤液中有机组分(用CODCr表示)和氨氮在不同含水介质中的迁移规律和特征,并通过实验数据计算了延迟因子、COD衰减率和氨氮的单位质量介质吸附量等参数.结果显示,COD在中砂、细砂和粉土中迁移的延迟因子分别为1.13、1.23和1.24,表明有机物在三种实验介质中只发生轻微的延迟作朋;CODCr在三种介质中的自然衰减率分别为50.8%、55.2%和64.8%;氨氮的迁移由于吸附作用发生明显的延迟,其在上述三种介质中迁移的延迟因子和单位质量介质吸附最分别为3.30和194 mg·kg-1、3.91和223 mg·kg-1,以及5.12和280 mg·kg1;饱和条件下渗滤液中的氨氮较难发生硝化作用.上述结果可为评价垃圾渗滤液对地下水环境的影响提供技术参数.     

Distribution,bioavailability, and potential ecological risk of Cu,Pb, and Zn in soil in a potential groundwater source area

In this study, we examined three horizontal and vertical soil profiles along a sewage drainage ditch in order to determine the spatial distribution of Cu, Pb, and Zn in soils and to assess the bioavailability and potential ecological risks associated with these metals in a potential groundwater source area. Results showed that the concentrations of Cu, Pb, and Zn were approximately at background level, suggesting that human activities (industrial and agricultural pollution) had a negligible influence on these metals in soil, and that the concentrations reflected the natural background levels in the study area. Cu, Pb, and Zn concentrations were slightly higher in topsoil (0–20 cm) than deeper in the soil profile. Using a modified BCR sequential extraction method to evaluate the mobility and bioavailability of metals showed that the potential bioavailability sequence of Cu, Pb, and Zn at three depths in the soil profile was in the order Cu?≈?Pb?<?Zn. The potential ecological risk from the metals was evaluated using risk assessment code, and the results suggest that Cu and Zn pose no or low risk, while there is a low or medium risk from Pb. Results from groundwater monitoring showed that the groundwater was not polluted by leaching from soil.     

便携式重金属测定仪在龙江河镉离子污染事件应急监测中的应用研究

PDV6000plus便携式重金属测定仪具有体积小、精度高、操作简便等特点,能够快速完成样品分析,为环境管理部门在突发环境污染事件中及时掌握污染变化趋势,作出科学决策提供技术支持。本文通过介绍便携式重金属测定仪在广西龙江河镉离子污染事件应急监测中的具体应用,以期为今后在应急监测中更好地发挥作用提供参考。     

总有机碳分析仪测定水中的游离二氧化碳

利用总有机碳分析仪、结合酸化吹气装置对水样中的游离二氧化碳的测定条件进行试验。结果表明水浴温度80℃,流量150 ml/min通氮气30 min为水样释放游离二氧化碳的最佳条件。总有机碳分析测定水中游离二氧化碳含量方法的建立为水质分析提供了新的方法参考。     

苯酚羟化酶基因工程菌转化4-乙烯基苯酚特性研究

4-乙烯基苯酚广泛用作食品的调味剂及聚4-乙烯基苯酚类聚合物等的合成。近年来,研究发现4-乙烯基苯酚是苯乙烯在小鼠和人体中的次要代谢物,具有肝毒性和呼吸毒性。因此,利用生物定向转化技术降低4-乙烯基苯酚的毒性将具有实际意义。文章考察了含苯酚羟化酶基因的工程菌PH_IND生物转化4-乙烯基苯酚的条件,确定其最优条件为:菌株PH_IND的OD600为2.5,4-乙烯基苯酚的浓度为1 mmol/L,葡萄糖浓度为20 mmol/L,缓冲溶液的pH为8。在该条件下,生物转化呈一级动力学趋势,反应180 min后,转化率为31%。分子对接结果表明,4-乙烯基苯酚可以和苯酚羟化酶大亚基的活性位点结合,液相色谱-质谱联用分析结果表明4-乙烯基苯酚被转化为4-乙烯基儿茶酚。     

草原区煤炭开发的生态问题及其税费改革对策

锡林郭勒盟是我国重要的煤炭能源基地,近年来,煤电一体化开发为地区带来经济效益的同时也给环境带来巨大压力,大面积的草原受到破坏和威胁,引发了一系列生态问题,需要在锡盟未来的地区经济发展中引起注意。应该借鉴国际上对煤炭业开征环境保护税的经验,进行我国草原区煤炭业环境保护税费改革的制度设计和政策落实。     

Effects of penconazole enantiomers exposure on hormonal disruption in zebrafish Danio rerio (Hamilton, 1822)

Environmental Science and Pollution Research - PEN is a widely used triazole fungicide, usually used to control grape white rot. In the process of agricultural use, PEN will be scattered to the...