A Comparison of Measured and Simulated Ozone Concentrations in the Rural Areas of the Eastern United States during Summer 1995

ABSTRACT

The recent regulatory actions toward a longer-term (i.e., 8-hr) average ozone standard have brought forth the potential for many rural areas in the eastern United States to be in noncompliance. However, since a majority of these rural areas have generally few sources of anthropogenic emissions, the measured ozone levels primarily reflect the effects of the transport of ozone and its precursor pollutants and natural emissions. While photochemical grid models have been applied to urban areas to develop ozone mitigation measures, these efforts have been limited to high ozone episode events only and do not adequately cover rural regions. In this study, we applied a photochemical modeling system, RAMS/UAM-V, to the eastern United States from June 1-August 31, 1995. The purpose of the study is to examine the predictive ability of the modeling system at rural monitoring stations that are part of the Clean Air Status Trends Network (CASTNet) and the Gaseous Pollutant Monitoring Program (GPMP).

The results show that the measured daily 1-hr ozone maxima and the seasonal average of the daily 1-hr ozone maxima are in better agreement with the predictions of the modeling system than those for the daily 8-hr ozone maxima. Also, the response of the modeling system in reproducing the measured range of ozone levels over the diurnal cycle is poor, suggesting the need for improvement in the treatment of the physical and chemical processes of the modeling system during the nighttime and morning hours if it is to be used to address the 8-hr ozone standard.     

Do We Understand Trends in Atmospheric Sulfur Species?

ABSTRACT

Anomalies appear to exist in our understanding of atmospheric sulfur compounds, specifically as evidenced in the time trends of the different chemical forms of these compounds. Trends determined at a number of locations by several different groups seem to indicate that, responding to emission reductions across North America, the concentration of SO₂ in the atmosphere is declining more rapidly than that of aerosol SO₄ ^2-. A number of possible reasons for this discrepancy are examined, but it is not possible to provide a definitive answer at this stage. The intent is to stimulate debate, because shortcomings in our understanding of the processes involved could have profound implications for the credibility of abatement strategies and policies for both acid deposition and fine particulate matter (PM).     

Effects of unregulated anthropogenic activities on mixing ratios of volatile organic air pollutants—A case study

During the months of October to November, many important festivals are celebrated in India. Celebration of these festivals are marked by extensive use of fireworks or pyrotechnics, bonfire, incense burning, open air community cooking, and temporary eateries using crude fuel such as coal, wood, kerosene, cow dung, burning of raw/semiwood, and coconut shells. The present study deals with the influence of these unregulated anthropogenic activities on ambient mixing level of volatile organic compounds (VOCs), especially some carbonyl compounds. The study was undertaken in the metropolitan city of Kolkata, India, with very high population density, which is even higher during festival period. The average total carbonyl level at different sites in Kolkata varied from 134.8 to 516.5 μg m^?3 in pre-festival season, whereas in post-festival season the same varied from 252.2 to 589.3 μg m^?3. Formaldehyde to acetaldehyde ratio altered from 0.62 in pre-festival season to 1.78 in post-festival season. Diurnal variation also altered, indicating variation in source composition of carbonyls. The total ozone forming potential calculated for all 14 carbonyls in pre-festival season increased by 35% in post-festival season. The effect of anthropogenic activities typical to the event of Diwali night characterized by intense execution of pyrotechnics resulted in significantly high level of carbonyl VOCs. Principal component analysis study for the event of Diwali shows clear contribution of the event on certain carbonyl VOCs. The results indicate elevated primary emissions of these pollutants and also their effect on formation of secondary pollutants. The study emphasizes the need of generating awareness among the communities in society as well as need for regulations to minimize the emissions and related hazards to the extent possible.

Implications: Altered anthropogenic activities typical of festival season including extensive use of pyrotechnics affect ambient level of volatile organic compounds, especially some carbonyls. Such activities have considerable effect on interspecies ratio and diurnal variation. They also affect formation of secondary pollutants such as tropospheric ozone. Principal component analysis (PCA) study shows clear contribution of the pyrotechnics execution on certain carbonyl VOCs. The findings emphasize the need of generating awareness in society and need for regulations to minimize the emissions.     

Characterizing Long-Term Land Use/Cover Change in the United States from 1850 to 2000 Using a Nonlinear Bi-analytical Model

We relate the historical (1850–2000) spatial and temporal changes in cropland cover in the conterminous United States to several socio-economic and biophysical determinants using an eco-region based spatial framework. Results show population density as a major determinant during the nineteenth century, and biophysical suitability as the major determinant during the twentieth century. We further examine the role of technological innovations, socio-economic and socio-ecological feedbacks that have either sustained or altered the cropland trajectories in different eco-regions. The cropland trajectories for each of the 84 level-III eco-regions were analyzed using a nonlinear bi-analytical model. In the Eastern United States, low biophysically suitable eco-regions, e.g., New England, have shown continual decline in the cropland after reaching peak levels. The cropland trajectories in high biophysically suitable regions, e.g., Corn Belt, have stabilized after reaching peak levels. In the Western United States, low-intensity crop cover (<10 %) is sustained with irrigation support. A slower rate of land conversion was found in the industrial period. Significant effect of Conservation Reserve Program on planted crop area is found in last two decades (1990–2010).     

Biodiversity Conservation in a Changing Climate: A Review of Threats and Implications for Conservation Planning in Myanmar

High levels of species richness and endemism make Myanmar a regional priority for conservation. However, decades of economic and political sanctions have resulted in low conservation investment to effectively tackle threats to biodiversity. Recent sweeping political reforms have placed Myanmar on the fast track to economic development—the expectation is increased economic investments focused on the exploitation of the country’s rich, and relatively intact, natural resources. Within a context of weak regulatory capacity and inadequate environmental safeguards, rapid economic development is likely to have far-reaching negative implications for already threatened biodiversity and natural-resource-dependent human communities. Climate change will further exacerbate prevailing threats given Myanmar’s high exposure and vulnerability. The aim of this review is to examine the implications of increased economic growth and a changing climate within the larger context of biodiversity conservation in Myanmar. We summarize conservation challenges, assess direct climatological impacts on biodiversity and conclude with recommendations for long-term adaptation approaches for biodiversity conservation.     

抗生素最小抑制浓度法(MICs)评估环境大肠杆菌抗生素抗性

2015年世界卫生组织将抗生素的滥用列为21世纪最大的挑战之一,全球范围内抗生素抗药性的散播已严重威胁人类的健康。如何检测环境中的细菌抗药性,并有效评估抗药性感染的风险,是环境微生物研究的一项重要课题。本文通过改进的培养基微量稀释(broth micro-dilution)法,确定了2个地区(中国成都和美国夏威夷)不同环境来源(天然水系和市政污水)的大肠杆菌的抗生素最小抑制浓度(minimum inhibitory concentrations,MICs)。计算所得的MIC分位数(MIC50和MIC90)、菌体抗性百分比及多抗药性指数(multiple antibiotic resistance indexes,MARIs)显示两地不同环境区划的抗生素抗性存在明显的差异。天然水系(成都锦江)中的抗生素抗性是随时间可变的,与当地的降雨事件相关。环境菌株的抗药性模式通过聚类和非度量多维测度(non-metric multidimensional scaling,NMDS)进行分析。广谱β-内酰胺酶基因筛查显示出抗性基因与抗性表型之间的正相关性。结合现有的两地抗生素的使用数据讨论了两地环境抗生素抗性与当地人类活动及抗生素的使用实践之间的紧密联系。采集环境菌株抗生素MIC数据的实验及数据分析方法实现了环境抗药性的跨时空对比,为规范抗生素的区域性使用提供了指导作用。     

Characterization of Super Paramagnetic Nanoparticles Coated with a Biocompatible Polymer Produced by Dextransucrase from <Emphasis Type="Italic">Weissella cibaria</Emphasis> JAG8

Magnetic nanoparticles (MNPs) synthesised by chemical co-precipitation method was subjected to dextran coating by sonication method. The dextran was enzymatically synthesised by extracellular dextransucrase isolated from Weissella cibaria JAG8. The crystalline nature of MNPs and dextran coated MNPs were confirmed by X-ray diffraction studies with average particle size of 25 nm, which was confirmed further by high resolution transmission electron microscopy. The surface morphology of MNPs and dextran coated MNPs were monitored by scanning electron microscopy studies. The vibrating sample magnetometer investigation displayed the super paramagnetic nature of MNPs and dextran coated MNPs. FT-IR analysis of MNPs and dextran coated MNPs, displayed characteristic band of Fe–O bond at 582 cm^?1. Thermo-gravimetric analysis of MNPs and dextran coated MNPs (1:1) ratio displayed a weight loss of 15 and 18 %, which clearly indicated 3.0 % of dextran was coated on to the MNPs. The elemental composition study by scanning electron microscopy confirmed the association of dextran with MNPs. The in vitro effect of MNPs and dextran coated MNPs was performed on human colon cancer (HT-29) cell lines and the results showed that dextran coated: MNPs (2:1) displayed good biocompatibility results over dextran coated: MNPs (1:1) and un-coated MNPs.     

Inconsistent definitions of "urban" result in different conclusions about the size of urban carbon and nitrogen stocks

There is conflicting evidence about the importance of urban soils and vegetation in regional C budgets that is caused, in part, by inconsistent definitions of "urban" land use. We quantified urban ecosystem contributions to C stocks in the Boston (Massachusetts, USA) Metropolitan Statistical Area (MSA) using several alternative urban definitions. Development altered aboveground and belowground C and N stocks, and the sign and magnitude of these changes varied by land use and development intensity. Aboveground biomass (live trees, dbh > or = 5 cm) for the MSA was 7.2 +/- 0.4 kg C/m2 (mean +/- SE), reflecting a high proportion of forest cover. Vegetation C was highest in forest (11.6 +/- 0.5 kg C/m2), followed by residential (4.6 +/- 0.5 kg C/m2), and then other developed (2.0 +/- 0.4 kg C/m2) land uses. Soil C (0-10 cm depth) followed the same pattern of decreasing C concentration from forest, to residential, to other developed land uses (4.1 +/- 0.1, 4.0 +/- 0.2, and 3.3 +/- 0.2 kg C/m2, respectively). Within a land use type, urban areas (which we defined as > 25% impervious surface area [ISA] within a 1-km(2) moving window) generally contained less vegetation C, but slightly more soil C, than nonurban areas. Soil N concentrations were higher in urban areas than nonurban areas of the same land use type, except for residential areas, which had similarly high soil N concentrations. When we compared our definition of urban to other commonly used urban extents (U.S. Census Bureau, Global Rural-Urban Mapping Project [GRUMP], and the MSA itself), we found that urban soil (1 m depth) and vegetation C stocks spanned a wide range, from 14.4 +/- 0.8 to 54.5 +/- 3.4 Tg C and from 4.2 +/- 0.4 to 27.3 +/- 3.2 Tg C, respectively. Conclusions about the importance of urban soils and vegetation to regional C and N stocks are very sensitive to the definition of urban used by the investigators. Urban areas, regardless of definition, are rapidly expanding in their extent; a systematic understanding of how our development patterns influence ecosystems is necessary to inform future development choices.     

Estimation of fecal Coliform removal from domestic sewage in two sand filter column systems

The objective of the present research is to compare fecal coliform removal from two different sand column systems treating septic tank effluent over a range of hydraulic loading rates. Drain time measurements were performed to compare the hydraulic characteristic of the column systems at different hydraulic loading rates. Biochemical oxygen demand (BOD), total suspended solids (TSS), and pH were also measured for the septic tank effluent. A removal of the order of 99% for fecal coliform, TSS, and BOD in column effluent was achieved using the sand filter columns. The ‘break‐in’ period for determining the effectiveness of the sand filter columns is also discussed.