Effects of Vertical Temperature Difference on Soiling Index

Changes in contaminant levels at monitoring stations do not necessarily represent changes in emission levels, since variations in meteorological parameters determine the transport and diffusion of contaminants between sources and receptors. To estimate annual changes in emission levels, and thus of control program effectiveness, the meteorological stratification of data was employed to provide “comparable days.”

For San Francisco Bay Area photochemical oxidant data, simple criteria based on maximum temperature and on height of inversion base were selected. Temperature provided a readily available integrated index of solar energy input and of ventilation, while the inversion data added a vertical dilution factor.

An earlier study, employing only the temperature criteria, showed that oxidant levels on comparable warm days had nearly doubled from 1954 through 1962. The current study of oxidant data for 1962 through 1969 shows a gradual rise through 1965, and a sharp reversal in 1966, when for the first time a simultaneous decrease was noted at each benchmark station. Data through 1969 show that average oxidant levels have been maintained at this 25% lower plateau, with minor fluctuations at individual stations.

The general improvement in air quality since 1965 is attributed to the reduction of reactive organics emitted from stationary and automotive sources.     

Size Distribution of Particles That May Contribute to Soiling of Material Surfaces

ABSTRACT

This study investigated the effect of adding vanadium (V) to natural manganese oxide (NMO) in ammonia (NH₃) selective catalytic reduction (SCR). The addition of V to NMO decreased the catalytic activity at low temperatures by blocking the active site. However, the enhancement of catalytic activity was achieved by controlling NH₃ oxidation at high temperatures. From the NH₃ temperature programmed desorption and oxygen on/off test, it was confirmed that the amount of Lewis acid site and active lattice oxygen of the catalyst affects the catalytic performance at low temperature

IMPLICATIONS Recently, NMO and manganese oxide have been reported as SCR catalysts. They usually have only reported the reaction characteristics and catalytic activity on the NH₃ SCR over NMO or manganese/metal oxide catalysts. There are no studies about the effect of addition of V to NMO. Therefore, this study investigates the catalytic activity and reaction characteristics on the NH₃ SCR over NMO and V/NMO, and a new application is proposed based on the conclusions of this study.     

酸雨对建筑材料的影响及防治研究综述

综合分析了酸雨对建筑外墙的涂料、石材、混凝土等主要建筑构件的腐蚀原理,并提出了防治措施,来预防酸雨对建筑材料的侵害。     

Materials and sustainable development

Environmental Science and Pollution Research -     

Materials for alternative plant protection

Abstract

Information will be presented as to the use of various materials for alternative protection of crop plants against fungal pathogens.     

绿色高分子材料及其发展展望

介绍了环境友好的绿色高分子材料的重要性，列举了几种可降解高分子材料的类型及其特性，从可降解塑料的研制方面谈及充分、合理地利用资源，同时展望绿色高分子材料的应用前景。     

Selection of Adhesive-Coated Materials for Particulate Sampling

The use of adhesive surfaces for the collection and evaluation of airborne particulates, including radioactive dusts and aeroallergens, is steadily increasing. Although many types of adhesives and adhesive-coated materials are commercially available, very few are suitable for continuous monitoring applications. Late in 1 964, the Cincinnati Division of Air Pollution Control received a U. S. Public Health Service, Division of Air Pollution, Research Grant for the refinement and standardization of a method of particulate sampling utilizing adhesive surfaces as collection media. One of the first phases of this project was to select the adhesive-coated material best suited for the method. The research which led to this selection, from a group of 37 different materials, is reported.     

The Effects of Photochemical Oxidants on Materials

The excessive cracking of rubber products was one of the earliest indicators of the presence of atmospheric photochemical oxidants. It has been demonstrated that this excessive cracking of rubber is caused by atmospheric ozone formed in the photochemical smog formation process. Depending on the formulation of the rubber, cracking under stress can readily be detected within 3/4 hr when atmospheric oxidant levels are as low as 0.03 ppm. Natural and certain synthetic rubbers are particularly vulnerable. These rubbers when stressed show cracking when exposed to 0.02 ppm laboratory ozone for about 1 hr. Other materials known to deteriorate under atmospheric photochemical smog conditions are textiles and certain dyed fabrics, particularly under conditions of high humidity. Loss of tensile strength of cotton textiles when wet or moist, and similar fading of these dyed fabrics, particularly under high humidity, can be also produced by laboratory exposure of these textiles to pure ozone. Ozone effects on asphaltic materials ate also reported.     

Green Biomass Materials in Polyurethane Foams

Flexible polyurethane foams were prepared using naturally derived materials as alternatives to conventional auxiliary blowing agents. This research was based on the concept held by some that natural chemicals are better as a part of industrial ecology. The authors have attempted to define the foam manufacturing suitability of natural chemicals, but have not defined or defended the policy implications of such choices. Natural chemicals are often less suitable than those refined from petroleum and may then need some environmental credit related to greater discharge to be viable substitutes. Modest decreases in density (relative to foams without any auxiliary blowing agent) were obtained with the addition of solid CO₂ but other physical properties were not measured. It is unclear whether the reduction in density is a result of the phase change of CO, from solid to liquid within the polyurethane cell matrix or simply a bubbling effect of C02 in solution causing voids within the final product. Although it was anticipated that the high boiling point of limonene, from citrus peeis, would negate effectiveness as an auxiliary blowing agent, there were analogous decreases in foam density. The observed effect might be rationalized by the significant vapor pressure of limonene at temperatures lower than the boiling point. The limonene may be sweptf rom the foam system coincident with the loss of in situ generated CO₂ isoprene, naturally emitted from deciduous vegetation as well as from the combustion of carbonaceous fuels, provides a useful, if not complete, range of foam densities and may then be a partial substitute for halogenated auxiliary blowing agents. Switching from methyiene chloride to isoprene as the auxiliary blowing agent of choice would immediately decrease organic emissions from polyurethane foam plants by 20 percent (molecular weight effect). Regulation as a VOC and the residual acrid odor may be potential drawbacks to commercial utilization of isoprene.     

Impacts of Upstream Building Width and Upwind Building Arrangements on Airflow and Pollutant Dispersion in a Street Canyon

A two-dimensional numerical model for evaluating the wind flow and pollutant dispersion within a street canyon was first developed using the FLUENT code, which was then validated against a wind tunnel experiment. Then, the effects of the upstream building width and upwind building arrangement on the airflow and pollutant dispersion inside an isolated street canyon were investigated numerically. The numerical results revealed that: (1) the in-canyon vortex center shifts downwards as the upstream building width increases; (2) the recirculation zone covers the entire upstream building roof for the cases when W/H = 0.5, 1.0, 1.5, and 2.0 (W is the upstream building width and H is the building height), whereas the flow reattaches the upstream building roof for the cases when W/H = 2.5 and 3.0; (3) when the upstream building width is shorter than the critical width W_C (= 2H), an increase in the upstream building width leads to an increase in the pollution level on the leeward wall of the canyon and a decrease in the roof-level concentrations at the upstream building; (4) when the upstream building width is longer than the critical width, the roof-level concentrations at the upstream building are negligibly small and the pollution level on the leeward wall of the canyon is almost unaffected by a further increase in the upstream building width; (5) when the buildings are placed upwind of the canyon, the flow attaches the upstream building roof and, therefore, almost none of the pollutants are distributed on the upstream building roof; and (6) the pollution levels inside the canyon and on the downstream building roof increase significantly with the number of upwind buildings.     

Update on Building and Structure Decontamination

Cleanup of the nation’s hazardous waste sites is a top environmental priority. Since the ultimate objective of many cleanup programs is to return the contaminated site and buildings on the site to active use, additional information regarding both established and emerging technologies for building decontamination is needed.

A pilot scale study was performed at an actual Superfund Site to evaluate, side by side, the efficacy of PCB removal using two decontamination processes. One process entails use of a shotblasting technique in which contaminated concrete surfaces are cut away and physically removed. The other process involves application of an alkali metal/polyethylene glycolate mixture directly to contaminated concrete surfaces for insitu degradation of PCBs.     

工业含锌废料制备氧化锌纳米粒子

以工业含锌废料为原料，加硫酸，然后除杂，得硫酸锌，再加碳酸铵溶液，制备出径粒细小的碱式碳酸盐前驱体，干燥后，600℃焙烧1h，得到ZnO纳米粒子。     

绿色建筑的雨水收集和中水回用

文中介绍了绿色建筑中雨水收集的方案和流程,区域建筑中中水处理和回用以及目前存在的问题和雨水、中水的利用及前景。     

Air-Surface Exchange of Mercury with Soils Amended with Ash Materials

Abstract

Air-surface exchange of mercury (Hg) was measured from soil low in Hg (0.013 mg/kg) amended with four different ash materials: a wood ash containing ～10% coal ash (0.070 mg/kg Hg), a mixture of two subbituminous coal fly ashes (0.075 mg/kg Hg), a subbituminous coal ash containing ～10% petroleum coke ash (1.2 mg/kg Hg), and an ash from incinerated municipal sewage sludge (4.3 mg/kg Hg) using a dynamic flux chamber. Ash was added to soil to simulate agricultural supplements, soil stabilization, and pad layers used in livestock areas. For the agricultural amendment, ～0.4% ash was well mixed into the soil. To make the stabilized soil that could be used for construction purposes, ～20% ash was mixed into soil with water. The pad layer consisted of a wetted 1-cm layer of ash material on the soil surface. Diel trends of Hg flux were observed for all of the substrates with significantly higher Hg emissions during the day and negligible flux or deposition of Hg during the night. Hg fluxes, which were measured in the summer months, were best correlated with solar radiation, temperature, and air O₃ concentrations. Mean Hg fluxes measured outdoors for unamended soils ranged from 19 to 140 ng/m² day, whereas those for soil amended with ash to simulate an agricultural application ranged from 7.2 to 230 ng/m² day. Fluxes for soil stabilized with ash ranged from 77 to 530 ng/m² day and for soil with pads constructed of ash ranged from ?50 to 90 ng/m² day. Simple analytical tests (i.e., total Hg content, synthetic precipitation leaching procedure, heating, and indoor gas-exchange experiments) were performed to assess whether algorithms based on these tests could be used to predict Hg fluxes observed outdoors using the flux chamber. Based on this study, no consistent relationships could be developed. More work is needed to assess long-term and seasonal variations in Hg flux from (intact and disturbed) substrates before annual estimates of emissions can be developed.     

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m^?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m^?3), followed by styrene (21.24 μg m^?3), 2-ethyltoluene (17.11 μg m^?3), n-hexane (10.21 μg m^?3) and benzene (9.42 μg m^?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.     

浅议环境预警监测常态化建设

阐述了中国环境预警监测存在的主要问题:监测信息支持系统不够先进、科学;优先监测对象未经优化论证;预警监测能力滞后;应急监测在应急处置工作中处于被动局面。在此基础上,笔者提出了强化环境预警监测应当确立常态化管理意识;开发监测信息支持系统;加强应急监测能力建设;组织各种应急演练等对策建议,对基层环境监管具有借鉴作用。