我国城市街尘重金属污染研究进展与趋势

国外城市街尘重金属污染研究较早,国内相关研究虽起步较晚,但发展迅速。本文搜集了近10a来中国城市街尘重金属污染研究的主要成果,从重金属含量、空间分布特征、赋存形态、污染来源以及污染影响评价等方面进行详细梳理,并就未来我国城市街尘重金属污染研究的发展趋势提出了一些建议。     

WATER POLLUTION AS AFFECTED BY STREET SALTING1

The use of salt to melt ice and snow on streets and roads has become prevalent throughout the Northeast. Several states apply as much as 20 tons per lane-mile. Salt runoff may be sorted in various locations within the hydrologic system. Eventually the salt reaches streams and lakes. In Meadowbrook, it was observed that the chloride content reached a high of 11,000 ppm in December 1969. The runoff from the watershed was emitted in several surges. Chloride concentrations declined with the onset of summer, but still remained high, suggesting that some of the salt applied during the past winter appeared in the summer stream flow. Salt runoff entering a small lake, flowed directly to the lake bottom. The buildup of high density saline water in the lower portion of the lake prevented complete mixing in the spring. Incomplete mixing led to anoxic conditions in the lower lake strata. The population of bent hic fauna of the lake was changed by the flow of salt water into the lake. From a total of 10 species of dipteran larva and oligochaetes, only 4 species of the latter remained.     

三峡库区退化土壤的恢复与重建研究

三峡库区是一个生态环境背景较为脆弱且人口压力巨大的丘陵山区,由于人类长期的过垦与破坏,土壤退化十分严重。因此,加强对库区退化土壤的恢复与重建势在必行。土壤恢复与重建包括土壤结构,养分和环境的恢复三个方面内容。     

城市街道地表物特性分析

通过对城市街道地表物的收集、处理、分析和典型降水的径流冲刷实测,全面探究了城市街道地表物的分布、累积和冲刷规律,并对其污染物的含量和污染物总量进行了定量计算。为现代城市非点源污染截污处理和环境综合整治提供了理论和实践依据。     

Dispersion of Pollutants in Street Canyon under Traffic Induced Flow and Turbulence

A 3-D Eulerian-Lagrangian approach to moving vehicles is presented that takes into account the traffic induced flow rate and turbulence. The method is applied to pollutants dispersion in a street canyon. The approach is based on CFD calculations using Eulerian approach to the continuous phase and Lagrangian approach to the "discrete phase" of moving objects - vehicles. A commercial CFD code StarCD was used into which the Lagrangian model was integrated. As an example a street canyon is taken into consideration. It has the length of 50 m and the aspect ratio of 1.27. The speed of wind was assigned values of 4, 7 and 12 m/s at the altitude of 300 m. The total height of the domain is 115 m. In the study different traffic situations are considered, namely one-way and two-way traffic with different traffic rates per lane. The predictions show that different traffic situations affect pollutants dispersion in the street canyon and that there are also differences in the pollutants dispersion in case of one- and two-way traffic.     

城市街道峡谷空气质量的初步研究

介绍了街道峡谷的定义及特征,通过对其空气质量进行初步研究,分析影响街道峡谷空气质量的因素,选择采样点位及监测技术,探讨了污染物迁移扩散的规律,提出今后街道峡谷研究的方向.     

西北典型工矿型城市街道尘埃重金属污染的环境磁学响应

以甘肃省白银市为研究区域,系统采集43个城区街道尘埃样品,并对其进行环境磁学和重金属元素特征分析.结果表明,白银市街道尘埃磁性特征以低矫顽力的磁铁矿和磁赤铁矿为主导,磁晶体粒径为较粗的假单畴(PSD)和多畴(MD)颗粒;样品低频磁化率(χlf)变化范围为(43.75~1 340.08)×10-8m3·kg-1,平均值为245.98×10-8m3·kg-1,与国内综合型大城市相比,白银市街道尘埃磁性矿物含量相对较低,但呈现明显的空间分布差异,表现为工业区高于带状交通区,带状交通区高于商业区,新城区磁性矿物含量较低;白银市各功能区污染源相对单一,工业污染对强磁性矿物的贡献占主导,污染程度空间分异显著.白银市街道尘埃样品中Cu、Pb、Zn整体含量较高,污染负荷指数(PLI)与低频磁化率(χlf)、非磁滞剩磁化率(χARM)、饱和等温剩磁(SIRM)、"软"剩磁(SOFT)相关性较高,且空间变化特征较为一致,表明反映磁性矿物含量的参数可以有效监测城市重金属污染,进而圈定重金属综合污染区域和范围,为进一步的城市污染治理工作提供快速有效的证据支持.     

Photocatalytic degradation of NOx in a pilot street canyon configuration using TiO2-mortar panels

Titanium dioxide is the most important photocatalysts used for purifying applications. If a TiO₂- containing material is left outdoors as a form of flat panels, it is activated by sunlight to remove harmful NOx gases during the day. The photocatalytic efficiency of a TiO₂-treated mortar for removal of NOx was investigated in the frame of this work. For this purpose a fully equipped monitoring system was designed at a pilot site. This system allows the in situ evaluation of the de-polluting properties of a photocatalytic material by taking into account the climatologic phenomena in street canyons, accurate measurements of pollution level and full registration of meteorological data The pilot site involved three artificial canyon streets, a pollution source, continuous NOx measurements inside the canyons and the source as well as background and meteorological measurements. Significant differences on the NOx concentration level were observed between the TiO₂ treated and the reference canyon. NOx values in TiO₂ canyon were 36.7 to 82.0% lower than the ones observed in the reference one. Data arising from this study could be used to assess the impact of the photocatalytic material on the purification of the urban environment.     

一种新型高铺展性水成膜泡沫的性质以及灭火性能研究

介绍了一种自制的多组分水成膜泡沫溶液,并对该泡沫溶液的各种性能(表面张力,铺展性,灭火性能等)进行了表征,同时与传统的水成膜泡沫进行了对比.试验结果表明,该泡沫溶液的表面张力和界面张力很低.极低的表面和界面张力导致该泡沫在液体燃料表面具有很强的铺展性,能在极短的时间内在燃料表面铺展成一层液膜,使燃料表面迅速隔氧降温,从而达到迅速灭火的作用.在通过压缩空气泡沫系统进行灭火的试验中,不论泡沫浓度处于3%或6%,在液体流量较大的情况下,该泡沫对标准柴油火的熄灭时间都在3秒之内.另外,泡沫溶液的铺展性和所形成的泡沫的灭火性能的试验结果表明水成膜泡沫的灭火速率主要是由其在燃料表面形成水膜的速率决定,而形成水膜的速率主要是由泡沫溶液的铺展速率、即铺展性决定的.     

太阳能路灯技术的国内外研究动态及其在浙江新农村建设中的应用

针对中国太阳能利用技术的现状，分析比较了太阳能路灯在国内利用的可行性，详细介绍了浙江某示范村的太阳能路灯工程情况，并对该工程进行了经济可行性的分析。