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401.
砂对海水中溶解油的吸附及影响因素研究 总被引:2,自引:0,他引:2
以柴油污染的海水为对象,研究了砂对海水中溶解油的吸附作用及吸附的影响因素。结果表明,砂对溶解油的吸附符合Henry型吸附等温式,其吸附量随着砂粒粒径的减小、温度的降低和盐度的增加而增大。在影响吸附的3种因素中,粒径对吸附的影响最大。通过吸附热力学分析,推断砂对溶解油的吸附属于物理吸附。 相似文献
402.
The measurement of roadway PM10 emission rates using atmospheric tracer ratio techniques 总被引:2,自引:0,他引:2
Ravi Kantamaneni Glen Adams Lee Bamesberger Eugene Allwine Hal Westberg Brian Lamb Candis Claiborn 《Atmospheric environment (Oxford, England : 1994)》1996,30(24):4209-4223
In this work, stationary and mobile point source tracer release techniques have been used to determine PM10 emission rates from four-lane commercial/residential paved roads under sanded and unsanded conditions, and from unpaved roads relative to site-specific vehicular and ambient parameters. Measured street (4 + lanes; ? 10,000 vehicles per day) emission factors for unsanded and sanded roads were 40 and 20% lower, respectively, than the EPA approved reference value. The sanded road emission factor was approximately 40% higher than that for the unsanded road. These results indicate a consistent relationship between PM10 and relative humidity under unsanded conditions. There is some evidence to suggest that street sweeping has a measurable effect on PM,, emission reduction during periods of low relative humidity (i.e. ? 30%). Within the constraints imposed by the variable experimental conditions, the emission factors determined for unpaved roads agreed reasonably well with the unpaved road empirical formula. Limited correlations were observed with ambient meteorological parameters. The capability of the “upwind-dowiawind” concentration modeling method to predict accurate emission was tested using a Gaussian dispersion model (SIMFLUX). Predictions agreed well with the experimentally determined emission factors. 相似文献
403.
Kazuhiko Sakamoto Hisae Takada Kazuhiko Sekiguchi 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):6961
To evaluate the influences of O3, relative humidity (RH), and flow rate on the reaction between yellow sand and SO2, the SO2 deposition velocity and the oxidation state of sulfur were investigated by means of exposure experiments in a cylindrical flow reactor. Early in the reaction, the deposition velocity was not influenced by the RH or the presence of O3; as the reaction progressed, however, the deposition velocity increased in the presence of O3 and at high humidity. The oxidation of sulfur from S(IV) to S(VI) was also enhanced under these conditions. The amount of sulfur oxidation was positively correlated with the amount of deposited O3. Furthermore, the SO2 deposition velocity increased with increasing flow rate. However, changes in the flow rate had no noticeable effect on the amount of SO2 oxidation. 相似文献
404.
Michael J. Hilton 《Environmental management》1994,18(6):815-829
The purpose of New Zealand's Resource Management Act (1991) is to promote the sustainable management of natural and physical
resources. Coastal sand mining may be consistent with this purpose where: (1) extractions occur from sediment systems open
to inputs of sediment, and the volumes extracted do not limit the natural development, physical characteristics, and ecological
diversity of the coastal environments affected; or (2) extractions from palimpsest or relict sedimentary deposits occur at
a rate where the rate of extraction is insignificant compared with the volume of the resource.
The response of coastal sand mining companies and consent-granting authorities to the requirements of the Resource Management
Act (1991) are examined with respect to recent applications to mine sand from a coastal sand body in the Hauraki Gulf, New
Zealand. The assessments of environmental effects (AEE) submitted in support of these applications do not establish the sustainability
of the sand mining operations. Specifically they do not define the dimensions of the active sediment system, quantify the
volume of the related resource, or state the period within which sustainability is achievable. Further, the AEE do not consider
the cumulative effects of the extractions, either in terms of the total volume of sand mined or the cumulative effects of
different anthropogenic activities.
The test of sustainability demands a quality of information and understanding of coastal systems that is well beyond that
obtained in the past or accepted at present. There is a clear need for New Zealand's resource management legislation to be
supplemented by technical guidelines that help ensure the test of sustainability is rigorously applied. 相似文献
405.
为了对挖掘荷载冲击下输气管道的动力响应情况与影响因素进行分析,利用ANSYS AUTODYN有限元软件对挖掘荷载冲击管道的过程进行数值模拟,根据仿真结果分析不同挖掘环境下管道的受损程度。研究结果表明:当受到挖掘荷载的作用时,管道的应力分布成对称状,在荷载作用位置单元处,有效应力达到最大值,且挖掘荷载大小与斗齿数对管道受损程度的影响较为明显。 相似文献
406.
《环境科学学报(英文版)》2023,35(7):104-114
Thallium contamination in water can cause great danger to the environment. In this study, we synthesized manganese oxide-coated sand (MOCS) and investigated the transport and retention behaviors of Tl(I) in MOCS under different conditions. Characterization methods combined with a two-site nonequilibrium transport model were applied to explore the retention mechanisms. The results showed that Tl(I) mobility was strongly inhibited in MOCS media, and the retention capacity calculated from the fitted model was 510.41 mg/g under neutral conditions. The retention process included adsorption and oxidative precipitation by the manganese oxides coated on the sand surface. Cotransport with the same concentration of Mn(II) led to halving Tl(I) retention due to competition for reactive sites. Enhanced Tl(I) retention was observed under alkaline conditions, as increasing pH promoted electronegativity on the media surface. Moreover, the competitive cation Ca2+ significantly weakened Tl(I) retention by occupying adsorption sites. These findings provide new insights into understanding Tl(I) transport behavior in water-saturated porous media and suggest that manganese oxide-coated sand can be a cost-effective filter media for treating Tl-contaminated water. 相似文献
407.
铁锰复合氧化物包覆海砂的吸附除磷研究 总被引:6,自引:1,他引:5
利用铁锰复合氧化物包覆海砂制备了一种用于污水除磷的新型颗粒状吸附剂,并对其表面特性与磷吸附行为进行了研究.扫描电镜(SEM)分析结果表明,包覆后海砂颗粒表面凹凸不平且多孔,BET比表面积由0.06增至2.52 m2·g-1.磷吸附实验结果表明,包覆后海砂对磷的吸附能力显著提高,最大吸附容量为1.01~1.23 mg·g-1,优于多数文献报道的负载改性砂颗粒吸附剂;吸附动力学更符合准二级动力学方程,推测磷在包覆海砂表面发生了化学吸附;溶液p H对磷吸附有一定影响,离子强度则影响不大;共存阴离子对磷吸附影响的大小顺序为Si O2-3CO2-3F-SO2-4Cl-. 相似文献
408.
409.
针对综掘工作面掘进过程中粉尘污染问题,设计了一种新型高效的风幕控尘除尘系统,利用风幕风速衰减试验分析了风幕风速与距出口距离衰减的关系,当风幕末端风速达到2 m/s以上就能够有效控制呼吸性粉尘逃逸,另外,利用数值模拟的方法,对风幕控尘除尘系统工作原理进行了模拟,当风幕初速度为15 m/s、除尘风筒负压为-250 Pa时,风流到达巷道壁时的风速均达到了3m/s以上,风幕控尘除尘系统起到了很好的控尘和除尘作用.并对压入式通风+湿式除尘机除尘的方式进行了数值模拟,压入式通风的风流大部分被除尘风筒吸入,掘进头和压入式风筒与除尘风筒重叠段形成了无风区,大部分粉尘颗粒和瓦斯不能够及时排出,给生产带来了极大的安全隐患. 相似文献
410.
Foam technology is more efficient than water sprays for dust control in coal mines, but the traditional foam system is complex and poses problems related to foam production and spraying application, with high water consumption, unstable equipment and relatively low utilization efficiency of foam. This paper describes an optimized foam system which overcomes these disadvantages. The proposed foam generator has a self-suction unit that uses a turbulent-flow water jet to automatically draw in ambient air and foaming agent, thereby eliminating the need for compressed-air hoses and pipes. As well as simplifying the system, it solves the current problem of water backflow created by high-pressure compressed air. A refined foam spraying structure was developed for use in conjunction with an operating roadheader as it produces and diffuses dust. The structure consists of foam distribution supports and arc-fan nozzles. It can produce a more focused, continuous and uniform coverage at the source of the dust. The optimized system consumes less water and foaming agent, and achieves greater dust-suppression efficiency than methods in current use. 相似文献