原 文：
Causes of Soil Contamination in the Urban Environment
Dust Deposition
Extensive dust deposition is mainly caused by industrial emission. It is deposited in dry conditions and as suspended particulate matter. The size of particulate matter varies. The fraction of less than 10 μm designated as respirable particulate matter is most dangerous for human health. A portion of cement dust and fly ash may exceed that value, but there are some kinds of particulate matter with a general size distribution of less than 10 μm like asbestos dust and smoke derived from oil-fired power stations. It should be borne in mind that the smaller the suspended matter is the higher the contaminant concentration is due to the enhanced sorption capacity.
Contaminated particulate matter can be transported from outdoors into rooms. There, a dust accumulation occurs, particularly if windows remain opened during daytime. Of interest is the comparison between garden soil and house dust concentration. In England it has been found that the Cd, Cu, Pb and Zn values were larger in house dust than in the associated gardens (Thornton 1991).
Dust formation in urban areas may play an important role, in particular in arid and semi-arid regions, where dry conditions dominates, but also in humid climates dust is of importance for soil formation. For instance, in the city of Hanover (Germany) with a population of 520,000, an enormous accumulation of 5–8 cm within 50 years was observed (Burghardt and Höke 2005). When dust development and deposition occurred without any filter technique systems, the deposited layer can reach enormous thickness as observed in vicinity of a coal processing factory in Halle (Germany) with its 230,000 inhabitants (Fig. 3.2).
One important feature of urban areas is the often exposed land surface you can never discover in woodland and pasture and over long periods percentages of bare soils are private gardens and allotments in wintertime, playing fields, cemeteries, demolition and building sites, derelict and disused, mostly industrial land, waste heaps, railway embankments, and storage sites, where permanent dust deposition occurs (Thornton 1991). In urban and industrial areas sealed sites are influenced as well, since dust may easily penetrate into gaps between pavement stones, cobbles as well as railway embankments, constantly filling them up. It is supposed that dust will be laterally transported on the pavement stones and ultimately concentrated in gaps downslope (Burghardt and Höke 2005).
It is logical to expect that urban soils show higher contamination levels than the rural areas because of their proximity to a number of potential pollution sources. Big cities like New York (USA) with 23,200,000 inhabitants are affected by several contamination sources, for instance simultaneous industrial emission, impact of traffic, deposits of technogenic substrates, etc. Consequently, a decline in e.g. Cu, Ni and Pb concentrations was found with increasing distance from the city centre (Manhattan) into the rural district outside of the city. While in Manhattan Pb topsoil values of more than 130 mg kg−1 were measured, at a distance of 50–60 km the values decreased to about 40 mg kg−1, and at a distance of 120–130 km to about 30 mg kg−1 (Pierzynski et al. 2005).
The urban-to-rural gradient has frequently been found in developed countries of the northern hemisphere. Figure 3.3 presents the lead concentrations of five relatively small towns in the United States. The contamination level of the urban lawn is comparably high, as would be expected by the vicinity and exposure to high levels of air pollution in urban environments. The air pollution is related to metallic aerosols from heavy industry as well as combustion of fossil fuel. The investigations referred to lawns close to houses and in parks. The high level has not to be restricted to the upper horizons and forest floors. The activity of earthworms and ants (bioturbation) may play a role in the long-term mixing of the humic topsoil and the mineral subsoil, causing translocation of contaminants like Pb (Craul 1992) (see Section 6.3).
A city – suburb gradient has been confirmed by the soil investigations of the upper 5 cm in Marrakech (Morocco) with 1,200,000 inhabitants (El Khalil et al. 2008). They collected material from nine sites according to a gradient from suburban (No. 1) to urban zones (No. 9) (Fig. 3.4a–c). It is obvious that the Cd, Cu, Ni and Zn values tend to increase the shorter the distance to the city centre is. However, other factors as well as the expected dust deposition close to the city influence the situation. With increasing distance to the historic city centre the anthropogenic disturbance of the soil profiles showed distinct fingerprints as well. The technogenic fraction in the upper soil layer reaches 14% at site No. 9, indicating the huge disturbance. The coarse technogenic fraction revealed similar values at a distance of approximately 500 m from historic centre. Behind this distance the percentage ranged between 1% and 2%. Because of their relatively high contamination level the findings may contribute to the soil pollution significantly (see Section 4.3). Both the factors dust deposition and the presence of technogenic substrates overlaps each other with reference to the topsoil contamination.
In general, dust concentration in industrial areas tends to be much higher than in residential and rural areas. In particular, in regions with factories that have a relatively low number of air pollution filter systems the differences between the areas are enormous. For instance, the emission of suspended particulate matter ranged between 360 and 500 μg m−3 in industrial catchments of several Indian cities, whilst in residential and rural areas the values varied from 140 to 200 μg m−3 only. In relation to the respirable particulate matter with a diameter less than 10 μm, the results were 120–150 μg m−3 for industrial areas and 60–100 μg m−3 for residential and rural areas (CPCB 2004).
If some industrial complexes with very high emissions such as heavy metal works are present, the soil contamination is going to reach extremely high values. As seen in Fig. 3.5a and b, the non-ferrous metallurgy plot in Pirdop (Bulgaria) with a population of 8,000 influenced the soil properties not only in the immediate proximity of the industrial plot. Apart from lead, the elements Cu and Zn revealed the same tendencies of decreasing values with increasing soil depth and with increasing distance from the source. Moreover, it is obvious that there is a dependence on the wind direction, since the concentrations may be enhanced predominantly in the main wind direction. Very high concentrations of heavy metals accumulated especially in the upper portion of the humic topsoils (Penin and Tschernev 1997).
The tendencies described associated with the heavy metal gradients are basically applicable to organic pollutants as well. Near the town of Strazske (Slovakia) with 5,000 inhabitants which is dominated by a chemical factory that produced technical Polychlorinated Biphenyls (PCB) mixtures between 1959 and 1984, samples were taken on an adjacent mountain slope influenced by the intensive dust emission and nearby deposition. As shown in Table 3.2, the accumulation of PCB (and Polycyclic Aromatic Hydrocarbons) in the organic layer exceeded the results from the mineral subsoil (depth gradient) and higher values tended to be found at the lower position of the neighbouring slope in direct contact with the emission source than at the central and upper position. In contrast to the heavy metals, the distance gradient seemed obviously to be less significant (Wilcke et al. 2003).
Industrial and mining processes influence increasingly the inventory of contaminants in the upper parts of the soils in the course of time. Trace elements usually in the earth’s crust in very small quantities reach high concentrations that would never have been found in the absence of industrial development. For instance, in Wyoming and Idaho, USA, dust-inducing surface mining of coal and phosphorus led to an increase of selenium in the environment due to the exposure of Se containing overburden (Pierzynski et al. 2005).
If soils of an urban environment are compared with heavy metal mining soils, an appreciable difference can be noticed. Thornton (1991) analysed topsoils of special mining villages and the British capital London, with a population of 13,200,000, with reference to all locations investigated in England and Wales (Table 3.3). In general, it was stated that the results from London are much higher than from all locations investigated as everybody would expect, but surprisingly, the concentrations of the mining villages exceeded the London results considerably, apart from cadmium. In other words, the urban impact apparently seems to be less significant than the mining impact.
With reference to urban environments, in the two Norwegian cities Bergen, with 230,000 inhabitants, and Trondheim, with 160,000 inhabitants, sensitive uses like gardens, parks, kindergartens and playgrounds were checked in order to ascertain the influence of dust deposition. Consequently, the upper 2 cm of the 661 (Bergen) and 631 (Trondheim) soil samples were taken into consideration. Bergen’s most important economic sectors are trade, shipping, the maritime industry and the public service. Trondheim has got a large number of companies producing and processing agricultural goods. For both cities, the main pollution sources discovered were in building maintenance (especially painting), industrial waste treatment, energy production, car traffic and the use of Cu-Cr-As impregnated wood. Much attention was paid to the latter source, because sand-pits in playgrounds and kindergartens were impregnated by copper, chromium and arsenic. Table 3.4 provides information about the soil concentrations of the two Norwegian municipalities. In detail, some areas were considered in order to confirm close correlations between some emitting factors and topsoil pollution nearby. The metals As, Cd, Cu, Pb, Se and Zn were more highly concentrated in the harbour area, where shipment of copper ore previously took place. Mercury was enhanced in proximity to a crematorium and a hospital incinerator. Near main roads there were accumulations of Hg, Pb and Zn (see Section 3.3.1). In general, some elements like Cd, Hg, Pb and Zn revealed increasing concentrations in the older parts of the city (Ottesen et al. 2000a, 2000b).
毕业论文外文翻译
外文题目: Causes of Soil Contamination in the Urban Environment
出 处: Contaminated Urban Soils Environmental Pollution
作 者: Helmut meuser
译 文：
城市环境土壤污染的原因
粉尘沉积
广泛的灰尘沉积，主要是工业排放造成的。这是存放在干燥的条件和悬浮颗粒物。这些颗粒物大小各不相同。不到10微米的可吸入颗粒物含量指定是最适合人类健康的危险界限。部分的水泥粉尘和粉煤灰可能超过该值，但也有一些小于10微米的微粒一般像石棉粉尘粒度因烟油发电厂而得的。应该注意的是较小的悬浮物，是高浓度的污染物，其吸附能力的增强污染越严重。
污染颗粒物可由户外运进入房间。在那里，一旦积尘发生，尤其是当窗户在白天开放时候。令人感兴趣的是、花园土壤和屋尘浓度比较。在英国已经发现镉，铜，铅，锌值在屋尘大于其在相关的花园（桑顿1991年）。
市区粉尘的形成可能起着重要作用，特别是在干旱和半干旱地区，那里干燥的环境下占主导地位，而且灰尘是土壤潮湿气候条件形成的重要部分。例如，在汉诺威（德国）52万人口的城市，一个在50年内5-8厘米的巨大积累的粉尘（瑞光和霍克2005年）。当灰尘发展和沉积技术没有任何过滤系统，巨大的沉积层厚度可以达到在一个在哈雷（德国）煤炭厂加工的情况。
城市地区的一个重要特点是经常暴露地表，你永远无法发现在林地和草场和在长期内裸土的百分比大部分是是私人花园和冬季拨款，运动场，墓地，拆迁和建筑工地，废弃和废弃，主要是工业用地，废物堆，铁路路基，和储存地点，在那里发生永久性的尘埃沉积（桑顿1991年）。在城市和工业区设密封网站的影响，以及，因为灰尘容易渗透到路面的石头之间的缝隙，卵石以及铁路路堤，不断填补起来。据推测灰尘会在人行道上横向运动，并最终在下坡（瑞光和霍克2005年）集中。
这是合乎逻辑的期望，城市土壤表明不是因为它们靠近潜在污染源的如农村地区高污染水平。大城市如纽约，二千三百二十〇万居民（美国）遭受多种污染源，如工业排放的同时，对交通的影响，存款技术性基板等，在如下降铜，镍，铅含量，发现随着进入农村地区距离市中心（曼哈顿）以外的城市。虽然在曼哈顿铅值超过130毫克公斤表土- 1的测量，在50-60公里的值下降到约40毫克公斤- 1的距离，并在该120-130公里的距离约30毫克公斤-1（Pierzynski等。2005年）。
在北半球的发达国家城市到农村梯度经常被发现。图3.3介绍了五个相对较小的美国城镇的铅浓度。城市草坪的污染程度相对比较高，这将由附近，暴露于高浓度的空气污染城市环境的预期。空气污染是重工业以及化石燃料的有关金属气溶胶的燃烧。该调查称草坪靠近房屋和公园。高级别并没有被限制到上层的视野和森林地板。可能是蚯蚓，蚂蚁（生物扰动）的活性在腐植表土和底土的矿物长期混合作用，导致污染物如铅（见6.3节）易位。
一个城市 - 郊区梯度已经证实了在高5马拉喀什（摩洛哥）厘米，1,200,000人（2008年萨尔瓦多哈利勒等。）土壤调查。他们收集的材料，从九个地点据来自郊区（第一号）梯度（第9号）（图3.4a - C）的城市区域。很明显，镉，铜，镍和锌的量往往会离城市中心距离较短。然而，其他因素以及预期的尘埃沉积靠近城市的影响情况。历史悠久的城市中心，人为干扰的土壤剖面也显示不同的指纹。在上面的土层技术性分数达到14％，9号在现场，显示了巨大的干扰。技术性部分的粗发现了约500米的距离历史中心相似的价值观。这个距离后面的百分比介于1％和2％。由于其相对较高的污染水平，这一发现可能有助于土壤污染研究（见4.3节）。这两个因素粉尘沉积和技术上存在重叠基板参考表层土污染对方。
一般来说，在工业区粉尘浓度往往比在住宅和农村地区高。特别是在工厂有一个空气污染过滤系统地区的数量与相对较少的地区之间的差别是巨大的。例如，悬浮颗粒物的排放量不等的几个印度城市，而工业集水区360和500微克之间的M - 3的住宅和农村地区介于140至200微克的M - 3只值。关于可吸入颗粒物的直径小于10微米的事，结果是120-150微克在工业区和60-100微克在住宅和农村地区（CPCB 2004年）。
如果具有非常高排放重金属等一些工业园区存在的话，土壤污染是要达到非常高的指标。Pirdop（保加利亚）有色金属冶金8000人口与密度不仅影响在工业小区紧邻的土壤性状。除铅，铜和锌的内容揭示了随着土壤深度的下降，并伴随着距离值相同的倾向。此外，很明显，有一个风向的依赖，因为浓度可能会随着主风向的方向浓度越高为主。非常高浓度的重金属积累了（Penin和Tschernev 1997年）土壤的上半部分，特别是胡敏表土。
所描述的与重金属梯度有关，以及有机污染物，基本上是适用的倾向。附近的Strazske（斯洛伐克）5000这是由化学工厂在1959年和1984年之间生产技术多氯联苯（PCB）的混合物产生的污染，样本被送往附近的山上在一个密集的沉积粉尘排放及附近斜坡的影响。如表3.2，PCB的积累在有机层（和多环芳香烃）所示底土的矿物超过了从（深度梯度）和高价值的结果往往是在邻近斜坡下的直接接触位置与发现其在中部和上部正电子发射源。与此相反的重金属，距离梯度似乎不那么明显差异（Wilcke等。2003年）。
在适当的时候工业和采矿过程中越来越多的影响土壤的上部污染物清单。高浓度的微量元素在地球的地壳通常是在非常小的数量达到，这个情况永远也不会在工业发展的情况下发现。例如，在怀俄明州和爱达荷州，美国，因为含有硒的（Pierzynski等。2005）磷矿开采，防尘表面诱导煤与导致环境中硒的增加。
如果拿一个城市环境与土壤重金属矿山土壤的环境相比，一个明显的差异就可以被看到。桑顿（1991）分析了表层土壤的特殊开采的村庄和英国首都伦敦的情况，参考了拥有13,200,000人口的英格兰和威尔士（表3.3）的调查的所有地点。在一般情况下，有人说，从伦敦的结果看大家都期望从调查的所有地点较高，但奇怪的是，从镉来说采矿村的浓度大大超过了伦敦的浓度结果。换句话说，城市的影响的显著性显然小于矿山采矿影响。
关于城市环境，在这两个挪威城市卑尔根的23万居民，和特隆赫姆16万居民，也喜欢花园，从公园，幼儿园及游乐场敏感的用途是检查，以确定粉尘沉积的影响。因此，高2661（卑尔根）和631厘米（Trondheim）的土壤样品进行了检查。卑尔根最重要的经济部门是贸易，航运，海运业和公共服务。特隆赫姆已得到了生产和加工农产品的大量企业。对于这两个城市的主要污染源建筑维修中发现（尤其是绘画），工业废物处理，能源生产，汽车行驶和使用的铜铬作为浸渍木材。许多注重后者的根源，因为砂坑在操场和幼儿园是由铜，铬，砷浸渍。表3.4提供了有关这两个挪威直辖市土壤浓度信息。具体而言，一些地区被认为是为了确认两者之间的一些因素和表层土壤污染状况的密切相关。金属砷，镉，铜，铅，硒，锌更高度集中在海港区，因为这里以前装运铜矿发生。特隆赫姆附近主要道路有汞，铅和锌的积累（见3.3.1节）。一般来说，像镉，汞，铅和锌的一些内容显示增加了城市的土壤浓度（Ottesen等。2000A型，2000年b）。
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