An Assessment of the Mobile Source Contribution to PM10 and PM2.5 in the United States

Mobile sources are significant contributors to ambient particulate matter (PM) in the United States. As the emphasis shifts from PM₁₀ to PM_2.5, it becomes particularly important to account for the mobile source contribution to observed particulate levels since these sources may be the major contributor to the fine particle fraction. This is due to the fact that most mobile source mass emissions have an aerodynamic diameter less than 2.5 µm, while the particles of geological origin that tend to dominate the PM₁₀ fraction generally have an aerodynamic diameter greater than 2.5 µm. A common approach to assess the relative contributions of sources to observed particulate mass concentrations is the application of source apportionment methods. These methods include material balance, chemical mass balance (CMB), and multivariate receptor models. This paper describes a number recent source attribution studies performed in the United States in order to evaluate the range of the mobile source contribution to observed PM. In addition, a review of the methods used to apportion source contributions to ambient particulate loadings is presented.     

Natural and Anthropogenic Contributions to PM10 and PM2.5 in an Urban Area in the Western Mediterranean Coast

Source apportionment analysis was used to identify the factors contributing to atmospheric pollution at a monitoring location in the Southeast of Spain, a well documented area with an arid climate and high insolation favouring two sources of particulate matter: secondary transformation in the atmosphere and resuspension of crustal dry soils to the air. These conditions are further complicated by numerous industrial facilities in the area of the historical city of Cartagena. This paper describes the air quality of an area which includes a zinc metallurgical industry, a petrochemical factory, an oil power station, a shipyard and natural phenomena including African dust transport and resuspension of regional and/or local crustal materials. Major and trace element concentrations in PM10 and PM2.5 were determined at two monitoring stations in Cartagena (one PM10 sampler located at a traffic hotspot and the PM2.5 sampler at a suburban station), during 2004 and 2005. Results showed that in the PM10 fraction, the zinc metallurgical activity was linked to high levels of Cd, Zn and Pb; shipyard emission was associated with high levels of Cr and Ni; and high Ni and V levels were associated with the secondary aerosol indicating the contribution from oil combustion (oil-fired power station or petrochemical facilities). In the PM2.5 size fraction, the zinc source is defined by Zn and Pb; V, Ni and As appear with the oil combustion emissions. In contrast to PM10, shipyard activity is not consistently defined. Consistent sources found in both size fractions include crustal materials and traffic emissions.     

PM10 and PM2.5 Levels in the Eastern Mediterranean (Akrotiri Research Station, Crete, Greece)

Particulate matter measurements (PM₁₀, PM_2.5) using a beta radiation attenuation monitor were performed at the Akrotiri research station (May 2003–March 2006) on the island of Crete (Greece). The mean PM₁₀ concentration during the measuring period (05/02/03–03/09/04) was equal to 35.0?±?17.7 μg/m³ whereas the mean PM_2.5 concentration (03/10/04–04/02/06) was equal to 25.4?±?16.5 μg/m³. The aerosol concentration at the Akrotiri station shows a large variability during the year. Mean concentrations of particulate matter undergo a seasonal change characterised by higher concentrations during summer [PM₁₀, 38.7?±?10.8 μg/m³ (2003); PM_2.5, 27.9?±?8.7 μg/m³ (2004) and 27.8?±?9.7 μg/m³ (2005)] and lower concentrations during winter [PM₁₀, 28.7?±?22.5 μg/m³ (2003/2004); PM_2.5, 21.0?±?13.0 μg/m³ (2004/2005) and 21.4?±?21.9 μg/m³ (2005/2006)]. Comparative measurements of the PM₁₀ concentration between the beta radiation attenuation monitor, a standardized low volume gravimetric reference sampler and a low volume sequential particulate sampler showed that PM₁₀ concentrations measured by the beta radiation attenuation monitor were higher than values given by the gravimetric samplers (mean ratio 1.17?±?0.11 and 1.21?±?0.08, respectively). Statistical and back trajectory analysis showed that elevated PM concentrations (PM₁₀, 93.8?±?49.1 μg/m³; PM_2.5: 102.9?±?59.9 μg/m³) are associated to desert dust events. In addition regional transport contributes significantly to the aerosol concentration levels whereas low aerosol concentrations were observed during storm episodes.     

PM2.5特征及森林植被对其调控研究进展

随着工业化进程的加快,人类活动对自然环境的影响越来越大,大气中PM2.5对人类健康的威胁逐步加剧,如何减轻PM2.5对人类的危害已经成为一个迫切需要解决的问题。通过分析国内外学者对PM2.5的研究成果,总结PM2.5的时空分布特征、组成特性、来源分类,以及世界主要国家、地区对PM2.5的监测标准,并基于森林植被对PM2.5的调控作用,指出通过合理建设森林植被达到有效调控PM2.5、降低PM2.5对人类的危害的目的。     

Al and Fe in PM 2.5 and PM 10 Suspended Particles in South-Central Florida: The Impact of the Long Range Transport of African Mineral Dust

Aluminum and iron were measured in daily samples collected at urban and rural sites near Ft. Myers, Florida, in 1995–1996 using a dichotomous sampler. Al and Fe concentrations were low during most of the year but they increased dramatically duringsummer when African dust was advected into Florida. The ratioof fine (less than 2.5 m diameter) to coarse (2.5–10 m) Al and Fe is relatively constant in African dust events with the fine accounting for a third to a half of the total. Also the mass ratio of Al-to-Fe is relatively constant at 1.8, a value similar to average crustal material. In contrast, in non-African dust the fine-to-coarse and Al-to-Fe ratios are extremely variable and generally much lower than those duringAfrican events when dust concentrations ranged up to 86 g m^-3. The timing and magnitude of the Ft. Myers dust peaks closely matched those measured concurrently in Miami, 200 km to the southeast. Large areas of the eastern United States are frequently impacted by African dust every summer. Although dustconcentrations can reach very high values it seems unlikely that African dust events alone will cause a violation of the Environmental Protection Agency's standards for PM 2.5 or PM 10. However, African dust in conjunction with emissions from local and regional sources could conceivably present a problemwith compliance. The probability of such an occurrence is heightened by the fact that dust concentrations are highest in the summer when pollution levels are often at a maximum in theeastern states.     

Source regions of summertime ozone and haze episodes in the eastern United States

During the summer of 1979, the mobile Atmospheric Research Laboratory (ARL) was sited near the Louisiana Gulf Coast to monitor the concentrations of air contaminants in air masses moving northward from the Gulf. Using the ARL data in conjunction with O₃ and visibility measurements across the entire eastern United States as well as synoptic meteorological data and satellite photographs, major source areas were identified. The haze which was observed on the Louisiana Gulf Coast appears to be primarily due to aged sulfate aerosols. The evidence presented strongly suggests that the sulfates were largely due to SO₂ emissions in the northeastern and midwestern United States. The haze initially formed over and downwind of these source areas and was transported to the Gulf Coast area. In the last two episodes, the haze was subsequently transported back to the Midwest source region. Elevated levels of O₃ were also associated with the haze. Again, the Northeast and Midwest appear to be the most significant source areas for the regional O₃ episodes. Occasionally, O₃ formed from emissions in the east Texas area also appear to affect a large portion of the Gulf Coast. In addition, each episode appeared to have a significant stratospheric air component based on⁷Be measurements. All three episodes followed the passage of upper levels troughs which produce stratospheric intrusions due to tropopause folding.     

基于AOD数据的新疆大型露天煤炭开采区PM2.5和PM10反演

MODIS气溶胶产品AOD与PM2.5、PM10浓度高度相关,已广泛应用在PM2.5、PM10浓度模拟.该研究以新疆维吾尔自治区大型露天煤炭开采区准东矿区为研究对象,结合实测的2014年5月、7月、9月、12月PM2.5、PM10质量浓度数据与经过垂直湿度订正的MODIS气溶胶产品AOD,利用多元回归进行拟合建模,从建立的40个模型中选取最优模型并据此对研究区PM2.5、PM10的质量浓度进行定量估算.结果表明:AOD与PM2.5、PM10呈极显著正相关;4个月AOD与PM2.5、PM10质量浓度估算模型最优模型均为多项式模型;其中7月AOD与PM2.5质量浓度拟合模型较好(R2=0.6258),实测值与预测值拟合趋势线R2为0.8057;9月PM10拟合模型效果理想(R2=0.7329),实测值与预测值拟合趋势线R2为0.8077;将AOD代入最优模型反演PM2.5,从空间层面上反映出各区域PM2.5浓度差异明显.研究结果可为AOD的深度利用与PM2.5、PM10浓度的遥感估算提供参考,在大气污染物空间分布、监测大气环境质量、污染预测等方面都具有重要意义.     

Spatial and Temporal Variation of PM10 Mass Concentrations within the Greater Area of Athens,Greece

The formation of chlorination by-products (CBPs) was investigated through bench-scale chlorination experiments with river water. The compounds selected for analysis belonged to the groups of trihalomethanes, haloacetic acids, haloketones and haloacetonitriles. Trihalomethanes and haloacetic acids were the major species formed during chlorination, while haloketones and haloacetonitriles occurred at lower levels. The factors affecting the formation of these compounds were examined by two sets of experiments; the first with varying pH and reaction time, and the second with varying chlorine dose and temperature. Different effects of these factors were observed for different categories of CBPs, and in many cases, these effects were compound-specific, as confirmed by statistical analysis. Optimization of chlorination conditions in water treatment plants is a critical issue that should take into account the influence of chlorination parameters on the formation of individual CBPs.     

A Study of PM2.5 and PM2.5-Associated Polycyclic Aromatic Hydrocarbons at an Urban Site in the Po Valley (Bologna, Italy)

PM_2.5 and PAHs bound to PM_2.5 were investigated in downtown Bologna, from January to June 2003, in order to determine the burden of the fine fraction in the aerosol of a typical urban environment of the Po Valley, a critical area in Northern Italy in terms of atmospheric pollution. The sampling campaign was divided into three parts: a winter sub-campaign, an intermediate campaign where PM_2.5 and PM₁₀ were simultaneously sampled and which identified PM_2.5 as the major component of PM₁₀, and a summer sub-campaign. Critical concentrations of both PM_2.5 and PAHs were observed in winter time; for example, in January 2003 the mean value for the 24-h average PM_2.5 concentration was 58 μg/m³, much higher than the annual arithmetic mean of 15 μg/m³ established by the US ambient air quality standard (NAAQS). Correspondingly, the mean value for benzo[a]pyrene (BAP) in PM_2.5 was 1.79 ng/m³, again higher than the annual mean of 1 ng/m³, required by European regulations for BAP in PM₁₀. In summer time the BAP concentration considerably decreases to 0.10 ng/m³ as the likely effect of photolysis and dilution on a higher boundary layer; PM_2.5 decreases too, but the mean concentration (22 μg/m³) is still higher than the NAAQS value. Further analysis included TEM microscopy of collected particles and correlations between PM_2.5, PAHs and gases (benzene, O₃, CO, NO₂, SO₂). All these observations identified on-road mobile sources as the main source of emissions and, in general, of the poor air quality level in the city of Bologna.     

Vitamin D and sterol composition of 10 types of mushrooms from retail suppliers in the United States

Vitamin D(2) (ergocalciferol) and sterols were analyzed in mushrooms sampled nationwide in the United States to update the USDA Nutrient Database for Standard Reference. Vitamin D(2) was assayed using HPLC with [(3)H]-vitamin D(3) internal standard and sterols by GC-FID mass spectrometric (MS) confirmation. Vitamin D(2) was low (0.1-0.3 μg/100 g) in Agaricus bisporus (white button, crimini, portabella) and enoki, moderate in shiitake and oyster (0.4-0.7 μg/100 g), and high in morel, chanterelle, maitake (5.2-28.1 μg/100 g) and UV-treated portabella (3.4-20.9 μg/100 g), with significant variability among composites for some types. Ergosterol (mg/100 g) was highest in maitake and shiitake (79.2, 84.9) and lowest in morel and enoki (26.3, 35.5); the range was <10 mg/100 g among white button composites but 12-50 mg/100 g among samples of other types. All mushrooms contained ergosta-5,7-dienol (22,23-dihydroergosterol) (3.53-18.0 mg/100 g) and (except morel) ergosta-7-enol. Only morel contained brassicasterol (28.6 mg/100 g) and campesterol (1.23-4.54 mg/100 g) and no ergosta-7,22-dienol. MS was critical in distinguishing campesterol from ergosta-7,22-dienol.     

Sagebrush conversion projects: An element of contemporary environmental change in the Western United States

Over 40 million ha of the western United States support a vegetative cover of big sagebrush, Artemisia tridentata. The meagre grass understory beneath the woody shrubs offers scant forage for range cattle, the primary economic product of the region. In order to improve grass supplies, both government agencies and private ranchers have undertaken a continuing programme of shrub eradication and grass planting. Various problems arise from this transformation of brushlands into grasslands, including questions of accelerated erosion, herbicide residues, and declining wildlife populations. If planned to produce a heterogeneous plant cover, however, sagebrush conversion projects could improve habitat for both domestic livestock and wildlife, while also maintaining a healthy range ecosystem.     

No-till and conservation agriculture in the United States: An example from the David Brandt farm,Carroll, Ohio

No-till (NT) farming (conservation agriculture) began in the US in the 1960s. The state of Ohio has a university research location that began no-till research in 1962. A few innovative Ohio farmers, including NT pioneers David Brandt and Bill Richards, were early adopters of the new conservation practice. Initially, no-till was most successful on sloping, well drained soils, then with improvements to the system, including cover crops, it became more widely adopted on all soil types. David Brandt was an enthusiastic learner and teacher of no-till practices, working with chemical company representatives and Cooperative Extension Specialists to demonstrate the system.David Brandt's cooperation with Ohio State University researchers continues to provide a valuable site for studying the long term changes in soil health and ecosystem services. Results showed that total microbial biomass as one of the soil biological health indicators significantly increased with an associated decrease in carbon (C) loss under NT compared with conventional tilled soil (CT). Under NT, there was significantly higher total C and total N compared to CT. Active C, as a composite measure of soil health, significantly increased with NT. When cover crops, especially cover crop cocktail mixes, were used, NT substantially improved soil health. Long-term NT with cover crop cocktail mixes significantly increased the soil aggregate stability, compared with CT. The overall rate of C sequestration by NT suggested that the soils on the Brandt farm act as a consistent sink of atmospheric CO2 although this tends to level off after about 20 years. The Brandt farm showed that crop yields are increased under long-term NT with cover crops mixes. Results suggested that starting with a cover crop when switching from CT to NT, is more likely to ensure success and to maintain economic crop yields.Another early adopter, Bill Richards, from Circleville, Ohio, also became a national leader and promoter of no-till farming. He served as head of the United States Department of Agriculture's Natural Resources Conservation Service in the early 1990s and instituted a program that led to rapid expansion of no-till. He advises that farmers who follow conservation agriculture principles need to be more proactive, from local level to national levels, to influence policy decisions that can lead to robust improvement in soil health.     

Comparison of quality characteristics of soybeans from Brazil, China, and the United States

Both soybean composition and processing conditions impact the nutritional quality of soybean meal. The objective of this experiment was to compare nutrient compositions of soybeans grown under diverse environmental conditions in a variety of locations. Dry matter, organic matter, and ash concentrations differed in soybeans collected within the countries of Brazil, China, and the United States, although these differences were generally small or due to uniqueness of a particular source. Large differences in dry matter were detected among countries. Differences in crude protein, amino acid, and lipid concentrations of soybeans were detected both within and among countries. Soybeans from China had a greater crude protein concentration (42.14%) than those from Brazil (40.86%), whereas soybeans from China had a lower lipid concentration (17.25%) than those from either Brazil or the United States (18.66 and 18.70%, respectively). Environmental conditions under which soybeans are grown have a great impact on chemical composition and nutrient quality.     

基于泰森多边形的南京市PM2.5时空特征及其与土地利用的相关性研究

[目的]分析南京市PM2.5时空分异规律,探讨PM2.5浓度变化与土地利用的关系,为南京市生态保护和空气污染治理决策提供依据。[方法]基于南京市2013年12个月的日均PM2.5浓度数据以及2013年土地利用数据,利用泰森多边形将南京市划分为9个研究区域,以月、季、年为时间尺度,对各个研究区内的PM2.5浓度的时空特征以及与土地利用的关系进行分析。[结果]时间上,南京市PM2.5浓度冬季呈现最高,达到129.93μg/m^3,夏季最低,达到44.65μg/m^3。空间上,迈皋桥和瑞金路监测区片年均浓度最高,达到78.90和78.56μg/m^3,仙林大学城和中华门监测区片年均PM2.5浓度最低,为72.09和72.64μg/m^3。在与土地利用类型的相关性分析中,与水域用地的相关性较强,春夏秋呈现正相关,冬季呈现负相关;年均PM2.5浓度与5种土地利用类型成不同程度的负相关。[结论]南京市PM2.5浓度具有明显的时空分异规律,土地利用类型对PM2.5浓度变化具有重要影响。     

Just Add Water and Salt: the Optimisation of Petrogenic Hydrocarbon Biodegradation in Soils from Semi-arid Barrow Island, Western Australia

We investigated the potential of soil moisture and nutrient amendments to enhance the biodegradation of oil in the soils from an ecologically unique semi-arid island. This was achieved using a series of controlled laboratory incubations where moisture or nutrient levels were experimentally manipulated. Respired CO₂ increased sharply with moisture amendment reflecting the severe moisture limitation of these porous and semi-arid soils. The greatest levels of CO₂ respiration were generally obtained with a soil pore water saturation of 50?C70%. Biodegradation in these nutrient poor soils was also promoted by the moderate addition of a nitrogen fertiliser. Increased biodegradation was greater at the lowest amendment rate (100 mg N kg^?1 soil) than the higher levels (500 or 1,000 mg N kg^?1 soil), suggesting the higher application rates may introduce N toxicity. Addition of phosphorous alone had little effect, but a combined 500 mg N and 200 mg P kg^?1 soil amendment led to a synergistic increase in CO₂ respiration (3.0×), suggesting P can limit the biodegradation of hydrocarbons following exogenous N amendment.     

Towards Excellence in Environmental Education A View from the United States

Within the United States, a nationwide debate has been raging over how to best provide quality education for all learners. Much of this debate, spurred by poor test scores and other measures of achievement, has centered on the development of national, state and local standards and assessments for the core disciplines (e.g., mathematics, science, geography). For the most part, environmental education has been left out of this debate and out of the various standards development initiatives. Whether one agrees philosophically with academic standards or not, these standards are determining what is being taught in the classroom. By 1993, environmental education in the United States found itself in a conundrum. It has always been argued that environmental education should be interdisciplinary, infused throughout the curriculum. However, with the new standards, environmental education was in real danger of becoming marginalized. To address this situation, the North American Association for Environmental Education (NAAEE) initiated the National Project for Excellence in Environmental Education.