常青道路景观配置对交通噪声的衰减效果

选取重庆市主城区常见的3种道路景观植物——石楠(阔叶类植物)、小叶黄杨(中等叶子类植物)和雪松(针叶类植物),研究常青道路植物对交通噪声的衰减效果。结果表明:(1)在相同排列条件下,3种植物的降噪能力依次为石楠>小叶黄杨>雪松。对单一植物种,植物间交叉排列的绿化带对交通噪声的衰减效果比平行排列好。(2)不同种类植物对噪声的插入损失峰值所处的频段不同。针叶类植物对低频(<500Hz)噪声有很好的衰减效果,阔叶类植物对高频(>2 000Hz)噪声有很好的衰减效果,中等叶子类植物对中频(500～2 000Hz)噪声有很好的衰减效果。(3)选择针叶类植物和较大冠幅的阔叶类植物搭配种植,如雪松和石楠,可有效地提高绿化带对各频段的交通噪声的吸收能力。     

道路交通噪声预测模式预测结果的比较

为了分析实际环境影响评价中常用的各种公路交通噪声预测模型预测结果之间存在的差异,并验证各预测方式与实测值之间的相符性,通过对选取的高速公路和市政快速公路采用各种预测模型计算比较,并用实际监测值对各模型预测结果进行验证,结果发现,不同的预测方式会造成预测结果之间昼间4～9 dB、夜间5～10 dB的差异,采用2006版规范计算车速和单车噪声源强,距离衰减考虑车流量大小的预测方式得到的预测结果与实测值最为接近。     

Natural attenuation/phytoremediation in the vadose zone of a former industrial sludge basin

The natural attenuation of polyaromatic hydrocarbons (PAHs) in the vadose zone of a naturally revegetated former industrial sludge basin (0.45 ha) was examined. This was accomplished by comparing the concentration of 16 PAH contaminants present in sludge collected below the root zone of plants with contaminants present at 3 shallower depths within the root zone. Chemical analysis of 240 samples from 60 cores showed the average concentration of total and individual PAHs in the 0-30 cm, 30-60 cm, and bottom of the root zone strata were approximately 10, 20, and 50%, respectively, of the 16, 800 ppm average total PAH concentration in deep non-rooted sludge. Statistically significant differences in average PAH concentrations were observed between each strata studied and the non-rooted sludge except for the concentrations of acenaphthene and chrysene present at the bottom of the root zone in comparison to sludge values. The rooting depth of the vegetation growing in the basin was dependent on both vegetation type and plant age. Average rooting depths for trees, forbs (herbaceous non-grasses), and grasses were 90, 60, and 50 cm, respectively. The deepest root systems observed (100-120 cm) were associated with the oldest (12-14 year-old) mulberry trees. Examination of root systems and PAH concentrations at numerous locations and depths within the basin indicated that plant roots and their microbially active rhizospheres fostered PAH disappearance; including water insoluble, low volatility compounds, i.e. benzo(a)pyrene and benzo(ghi)perylene. The reduced concentration of PAHs in the upper strata of this revegetated former sludge basin indicated that natural attenuation had occurred. This observation supports the concept that through appropriate planting and management practices (phytoremediation) it will be possible to accelerate, maximize, and sustain natural processes, whereby even the most recalcitrant PAH contaminants (i.e. benzo(a)pyrene) can be remediated over time.     

Spatial and diurnal variations in concentration of atmospheric NOx along urban-rural roadways in Nanjing, Southeastern China

Atmospheric NO_x concentrations (including NO₂ and NO) on the roadside environments of urban trunk, belt highway and suburban road as well as a reference in a forest area were measured. NO_x concentrations on roadside environments tended to be higher than that on the reference. With the exception of suburban road, NO_x concentrations over both of the urban trunk and belt highway exceeded the limited value of National Air Environmental Quality Standards. Gradient measurement of NO_x on the downwind side of the belt highway shows that it declined to background level over 100 m from the road edge.     

PAH dissipation in spiked soil: impacts of bioavailability, microbial activity, and trees

While trees have demonstrated potential in phytoremediation of several organic contaminants, little is known regarding their ability to impact the common soil contaminant PAHs. Several species of native North American trees were planted in soil artificially contaminated with three PAHs. Plant biomass, PAH dissipation, and microbial mineralization were monitored over the course of one year and environmental conditions were allowed to follow typical seasonal patterns. PAH dissipation and mineralization were not affected by planting. Extensive and rapid loss of PAHs was observed and attributed to high bioavailability and microbial activity in all treatments. The rate of this loss may have masked any significant planting effects. Anthracene was found to be more recalcitrant than pyrene or phenanthrene. Parallel soil aging studies indicated that sequestration to soil components was minimal. Contrary to common inferences in literature, amendment with decaying fine roots inhibited PAH degradation by the soil microbial community. Seasonal variation in environmental factors and rhizosphere dynamics may have also reduced or negated the effect of planting and should be taken into account in future phytoremediation trials. The unique root traits of trees may pose a challenge to traditional thought regarding PAH dissipation in the rhizosphere of plants.     

Shade trees reduce building energy use and CO2 emissions from power plants

Urban shade trees offer significant benefits in reducing building air-conditioning demand and improving urban air quality by reducing smog. The savings associated with these benefits vary by climate region and can be up to $200 per tree. The cost of planting trees and maintaining them can vary from $10 to $500 per tree. Tree-planting programs can be designed to have lower costs so that they offer potential savings to communities that plant trees. Our calculations suggest that urban trees play a major role in sequestering CO2 and thereby delay global warming. We estimate that a tree planted in Los Angeles avoids the combustion of 18 kg of carbon annually, even though it sequesters only 4.5-11 kg (as it would if growing in a forest). In this sense, one shade tree in Los Angeles is equivalent to three to five forest trees. In a recent analysis for Baton Rouge, Sacramento, and Salt Lake City, we estimated that planting an average of four shade trees per house (each with a top view cross section of 50 m2) would lead to an annual reduction in carbon emissions from power plants of 16,000, 41,000, and 9000 t, respectively (the per-tree reduction in carbon emissions is about 10-11 kg per year). These reductions only account for the direct reduction in the net cooling- and heating-energy use of buildings. Once the impact of the community cooling is included, these savings are increased by at least 25%.     

从竣工环境保护验收调查分析公路噪声环评的有效性

从所选的40条公路的竣工环境保护验收报告入手,对公路建成后与环境影响评价阶段噪声敏感点的数量变化、噪声实测值与环评预测值的差异、实际的噪声防治措施与环评确定措施的差异进行了对比分析.结果表明,以上3个方面在公路建成后与环评阶段均存在较大变化,公路噪声环境影响评价的有效性亟待提高.造成这一状况的主要原因包括项目投资机制、运营期相关条件变化等.通过分析,提出了实现全过程的环境影响评价与管理、提高预测的准确性及增强防噪措施的可操作性等促进环评有效性的相关对策建议.     

Heavy metals in fresh snow collected at different altitudes in the Chamonix and Maurienne valleys,French Alps: initial results

The Chamonix and Maurienne valleys, French Alps, are major pathways for international truck and automobile traffic in Western Europe since they give access to the transalpine Mont Blanc and Frejus road tunnels. Moreover, the seasonal snow pack, which accumulates from autumn to spring in these two valleys, is a major contributor to fresh water resources for a large number of people, especially in large cities such as Geneva, Lyon and Grenoble. During winter 1998, we have collected a series of snow samples from two well-identified snowfall events at various altitudes ranging from 1150 to 3532 m on the sides of these two deep valleys. They were analysed for Li, B, Ti, V, Mn, Fe, Co, Cu, Zn, Mo, Pd, Ag, Cd, Sn, Sb, Ba, Pt, Au, Pb, Bi and U by double focusing inductively coupled plasma mass spectrometry with micro concentric nebulization (DF-ICP-MS-MCN). Ultraclean procedures were used for field sampling and laboratory analysis. The results show surprisingly low concentration values. With the exception of Li, B, Pd, Sn, Pt and Au, concentrations are found to decrease with increasing altitude. Crustal enrichment factors larger than ±10 times the mean crustal abundance are observed for Cu, Zn, Li, Mo, Pb, Ag, Bi, B, Sb, Sn, Cd, Au, Pt and Pd, strongly suggesting contributions from non-crustal sources for these metals, especially local and/or regional anthropogenic sources. Significant contributions are likely to originate from truck and automobile traffic, electrometallurgical and electrochemical industries and municipal incinerators. These data provide with a unique snapshot of the situation which prevailed in the two valleys before the disaster which occurred on 24 March 1999 in the tunnel of Mont Blanc, which resulted into a massive fall of the traffic in the Chamonix valley and a parallel rise in the traffic in the Maurienne valley.     

Temporal changes in kerosene content and composition in field soil as a result of leaching

A field experiment was designed to determine the combined effect of leaching and natural attenuation on the redistribution dynamics of kerosene--a volatile petroleum hydrocarbon mixture (VPHM)--and of its selected individual components in the soil subsurface. Variables included the composition of contaminant spilled, the soil water content before contamination and the leaching pattern. Temporal changes in the residual kerosene concentration and composition in the soil subsurface of the experimental field during 39 days and leaching by 500 mm of irrigation water were determined to a depth of 100 cm. The main processes controlling contaminant attenuation were volatilization and redistribution with depth. Soil hydration status was found to affect the attenuation, redistribution and composition of VPHM in the porous media. An initial relative increase of n-alkanes in the subsurface compared with the total VPHM in the first leaching period was a result of the volatilization of low vapor pressure compounds. The redistribution of individual components in the soil profile during leaching was in accordance with their physico-chemical properties.     

How to select the best tree planting locations to enhance air pollution removal in the MillionTreesNYC initiative

Highest priority zones for tree planting within New York City were selected by using a planting priority index developed combining three main indicators: pollution concentration, population density and low canopy cover. This new tree population was projected through time to estimate potential air quality and carbon benefits. Those trees will likely remove more than 10 000 tons of air pollutants and a maximum of 1500 tons of carbon over the next 100 years given a 4% annual mortality rate. Cumulative carbon storage will be reduced through time as carbon loss through tree mortality outweighs carbon accumulation through tree growth. Model projections are strongly affected by mortality rate whose uncertainties limit estimations accuracy. Increasing mortality rate from 4 to 8% per year produce a significant decrease in the total pollution removal over a 100 year period from 11 000 tons to 3000 tons.     

Impacts of pavement types on in-vehicle noise and human health

Noise is a major source of pollution that can affect the human physiology and living environment. According to the World Health Organization (WHO), an exposure for longer than 24 hours to noise levels above 70 dB(A) may damage human hearing sensitivity, induce adverse health effects, and cause anxiety to residents nearby roadways. Pavement type with different roughness is one of the associated sources that may contribute to in-vehicle noise. Most previous studies have focused on the impact of pavement type on the surrounding acoustic environment of roadways, and given little attention to in-vehicle noise levels. This paper explores the impacts of different pavement types on in-vehicle noise levels and the associated adverse health effects. An old concrete pavement and a pavement with a thin asphalt overlay were chosen as the test beds. The in-vehicle noise caused by the asphalt and concrete pavements were measured, as well as the drivers’ corresponding heart rates and reported riding comfort. Results show that the overall in-vehicle sound levels are higher than 70 dB(A) even at midnight. The newly overlaid asphalt pavement reduced in-vehicle noise at a driving speed of 96.5 km/hr by approximately 6 dB(A). Further, on the concrete pavement with higher roughness, driver heart rates were significantly higher than on the asphalt pavement. Drivers reported feeling more comfortable when driving on asphalt than on concrete pavement. Further tests on more drivers with different demographic characteristics, along highways with complicated configurations, and an examination of more factors contributing to in-vehicle noise are recommended, in addition to measuring additional physical symptoms of both drivers and passengers.Implications: While there have been many previous noise-related studies, few have addressed in-vehicle noise. Most studies have focused on the noise that residents have complained about, such as neighborhood traffic noise. As yet, there have been no complaints by drivers that their own in-vehicle noise is too loud. Nevertheless, it is a fact that in-vehicle noise can also result in adverse health effects if it exceeds 85 dB(A). Results of this study show that in-vehicle noise was strongly associated with pavement type and roughness; also, driver heart rate patterns presented statistically significant differences on different types of pavement with different roughness.     

From Valuation to Governance: Using Choice Experiment to Value Street Trees

This paper reports a choice experiment used to estimate the value of street trees in the city center of Lodz, Poland, and the broader context of how valuation results helped to improve governance of urban ecosystem services in this city. Based on a simplified inventory of trees, we prepared a set of hypothetical programs which put varying emphasis on the different ways to increase the numbers of trees, along with different levels of a hypothetical tax that would have to be paid by respondents to implement a given program. Our study indicated that the 351 surveyed Lodz residents were willing to pay the highest price for greening those streets where currently there are few or no trees and confirmed the general importance of planting trees. The results provided an argument in the debate on the new development strategy for the city and helped to promote the concept of ecosystem services.     

室内箱式变压器结构声污染及对策

通过对置于住宅楼底层室内箱式变压器引起的结构声污染进行调查实测，在对箱式变压器结构声传播进行声学分析基础上，提出了切实可行的防治对策，经实际工程应用验证，效果较好。对机房正上方住房主卧内降噪量为5.0dB，室内夜间噪声降为30.2dB，各层住户夜间烦恼度普遍从非常烦恼或烦恼降为有点烦恼和不大烦恼。这从噪声污染控制的角度证明了变配电房置于住宅楼等噪声敏感建筑物室内底层甚至更高楼层在技术上是可行性的。同时也为杭州市正在试点推广的箱式变压器置于噪声敏感建筑物底层提供了实践依据。     

Oxygen transfer in a full-depth biological aerated filter

The City of San Diego, California, evaluated the performance capabilities of biological aerated filters (BAFs) at the Point Loma Wastewater Treatment Plant. The City conducted a 1-year pilot-plant evaluation of BAF technology supplied by two BAF manufacturers. This paper reports on the first independent oxygen-transfer test of BAFs at full depth using the offgas method. The tests showed process-water oxygen-transfer efficiencies of 1.6 to 5.8%/m (0.5 to 1.8%/ft) and 3.9 to 7.9%/m (1.2 to 2.4%/ft) for the two different pilot plants, at their nominal design conditions. Mass balances using chemical oxygen demand and dissolved organic carbon corroborated the transfer rates. Rates are higher than expected from fine-pore diffusers for similar process conditions and depths and clean-water conditions for the same column and are mostly attributed to extended bubble retention time resulting from interactions with the media and biofilm.     

柴油发电机噪声控制技术的应用

柴油发电机组噪声强,发热量大.通过对柴油发电机组提出隔声、消声、减振、通风散热的具体措施后,经工程实践证明,方案设计合理,达到预期的降噪效果,昼间等效声级＜60 dB(A),夜间等效声级＜50 dB(A),符合GB12348-90Ⅱ类排放标准.     

控制居住区交通噪声的建筑措施

首先分析了交通噪声对居住区声环境的影响,然后重点探讨相应的防治方法,特别是在居住区的规划中,就利用对噪声不敏感的建筑物和绿化隔离带形成小区周边的声屏障、合理布置小区道路系统并防止城市交通穿越、加强住宅建筑设计中隔声构造处理等方面提出了具体的技术措施。     

Effects of oxidant air pollution on Pinus maximartinezii Rzedowski in the México City region

The response of Pinus maximartinezii Rzedowski to photochemical oxidant air pollution was examined using 100 trees, during a 1 year cycle, at Vivero de Coyoacán, a tree nursery located in the south central part of México City, where exposure to polluted air masses has been continuous. The tree response assessment method was based upon documented symptoms of pollutant injury on the foliage. The results showed a homogeneous pattern of health and vigor and only medium sensitivity (based on foliar injury) to photochemical oxidants, although the trees maintained their needles through a three and not the normal 5 year period as at its geographic location of origin (different habitat or environment). Nevertheless, these data suggest that this species of pine could be proposed as good planting material for reforestation in the urban metropolitan area of México city.     

Traffic noise exposure of high-rise residential buildings in urban area

Noise pollution is a major factor of environmental complaints in many cities, which has significant impacts on human health. As a dominating source of environmental noise, the impact of road traffic noise is increasing. Residents living in high-rise buildings along the main road are severely affected by traffic noise. In order to assess the noise level of urban area along the main road in Guangzhou, three buildings were selected to conduct traffic noise measurements, and the questionnaire about traffic noise impact on human being was completed. Through the questionnaire, around 70% of participants consider the traffic noise has negative effect, and about 60% of participants consider the noise has moderate or much higher impact on physical comfort. Around 65% of participants consider the noise had moderately or much higher impact on their psychological comfort. By analyzing the measured data, all of the measured noise levels in three buildings exceed the recommended limit of 55 dB (A) in the daytime and 45 dB (A) in the night for residence, and the exceeded value can be up to 16 dB (A). By comparing the fitting curve of noise level transfer function on each floor relative to the reference floor, the quadratic polynomial was selected to plot the transfer function rather than cubic polynomial.

     

Assessing Secchi and photic zone depth in the Baltic Sea from satellite data

Long-term trends in the Secchi depth of the Baltic Sea have been interpreted in terms of eutrophication. The spectral attenuation coefficient Kd (490) can be estimated from remote sensing data. Given the empirical and theoretical relationships between diffuse attenuation and Secchi depth, it is therefore possible to estimate the trophic state from remote sensing data. This paper considers relationships among remotely sensed and in-water measured K (490), and Secchi depth data obtained during dedicated sea-truthing campaigns in the eastern Baltic Proper in 1999 (4) and in the western Baltic Proper/Himmerfj?rden area during 2001 and 2002. In-water measurements are used to establish the relationship between the PAR and the spectral attenuation coefficient in the Baltic Sea via regression analysis. The analysis showed that in the area of investigation Kd(490) is about 1.48 times higher than Kd (PAR). This relationship is then used to define the link between the photic zone depth and the remote sensing optical depth, Kd (490)-1. The results show that the depth of the euphotic zone is about 6.8 times Kd (490)-1. The regression analysis between Kd (PAR) and Secchi depth confirmed previous work that Kd (PAR) is about 1.7 of the inverse Secchi depth. Furthermore, an in-water algorithm between Secchi depth and Kd (490) is used to simulate a Secchi depth map of the Baltic Sea from SeaWiFS Kd(490) data. This map is verified against sea-truthing data. Kd (490) data derived from satellite is compared to in situ Kd (490), and the sources of error are discussed.     

室外大型空气压缩机的噪声治理技术

某室外安装的大型空气压缩机对环境造成了严重噪声污染,离机器2m远处噪声高达114 5dB(A)。在不允许停机的情况下,充分利用现场条件,采取了为空气压缩机加隔声罩、进气口滤清器加消声百页和管道作隔声包扎等综合治理措施,相应测点噪声已降至88 7dB(A),厂界噪声降至机器安装前背景值。室外机器的噪声控制方法与室内机器有许多不同,分析了这些差异并重点介绍了所设计的隔声罩在声学、通风、耐气候性和结构等方面的设计要点。