Emission of Volatiles from Polymers — A New Approach for Understanding Polymer Degradation

Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms, to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing. The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix, these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further to predict the long-term properties and remaining lifetime of the product.     

What factors control soil profile nitrogen storage?

Factors influencing soil profile nitrogen storage (SPNS) in GB have been investigated. The SPNS values of moorland peats and podzols in the South Pennines, of permanent grassland in Yorkshire, and of adjacent arable-, semi-permanent grassland- and ancient woodland-soils in Worcestershire have been compared to assess land use effects. The soils exhibited similar SPNS values, because changes in bulk density and organic matter composition offset increases in N concentrations in highly organic soils. Data from the Soil Survey of Scotland were used to show effects of soil parent material on SPNS were also small. Data on Scottish podzol soils under heather moorland and derived from sandstone or quartzite were used to show that SPNS declined with increasing precipitation, but increased with the amount of pollutant N deposited from the atmosphere.     

Sensitivity analysis of ground-level ozone concentration to emission changes in two urban regions of southeast Texas

Air pollutant emission is one of the predominant factors affecting urban air quality such as ground-level ozone formation. This paper assesses the impact of changing emission inventory scenarios, based on combinations of point, mobile, area/non-road and biogenic sources, on the tropospheric ozone concentration in two southeast Texas urban areas, i.e. Houston-Galveston and Beaumont-Port Arthur, during the rapid ozone formation event (ROFE) on August 25, 2000. The EPA's Community Multiscale Air Quality (CMAQ) modeling system with 1999 national emission inventory (NEI99) estimates and updated SAPRC99 chemical mechanism are used in the sensitivity analysis for twelve different emission scenarios. Based on model results, it is found that the point source emission of NOx and VOC contributes the greatest ozone peak in the ROFE. Removing Texas point sources of VOC and NOx emission from the inventory results in a reduction in peak O3 concentration by 128 and 70 ppbv in Houston urban area, respectively. Similar but less drastic impact from point source is also observed in the Beaumont-Port Arthur area. The effect on peak ozone concentration due to mobile, area and non-road sources emissions are less significant compared to that of point source emission. Reducing VOC emission appears to be more effective than reducing NOx emission in lowering peak O3 concentration in the studied region. Although biogenic emission can contribute up to 37 ppbv of peak ozone level over a large area, the affected area is away from the urban region of concern, and should not be the main cause for O3 non-attainment in the two urban areas. Removing CO emission from mobile sources does not lead to significant reduction (< 1 ppbv) in ozone concentrations. The modeled data also show that the transport of O3 precursors from adjacent states can cause a significant ozone plume near Beaumont due to its proximity to the state border based on the conditions during the August 25, 2000 O3 episode.     

Chemistry,Mineralogy and Morphology of Spodosols at Two Swedish Sites Used to Assess Methods of Counteracting Acidification

The chemistry, mineralogy and morphology of two soil profiles developed on till material of granitic and gneissic composition in south-western Sweden were studied in relation to podzolization processes. These soils were used for treatments with lime and wood ash. The profiles do not show characteristic Podzol morphology but qualify as Spodosols under Soil Taxonomy criteria and are probably typical for the coniferous forest soils of south-western Sweden. Podzolization features are clear but less well expressed than in classic Podzols. The distribution of major elements shows podzolization features with accumulation of sesquioxides in the B horizons and depletion in the eluvial horizons. Quartz and feldspars dominate the bulk soils reflecting the clear relationship between the composition of the soil and the underlying bedrock. Low amounts of clay contain an interlayered vermiculitic phase as the main phyllosilicate in which the degree of interlayering, known to be pH dependent, varies with depth and is at a maximum in the Bhs horizon. In the B horizons there are small but significant amounts of imogolite-type material which affect the adsorption of sulphate.     

从理论到实践的美国排污交易

阐述了排污交易产生的背景，排污权与排放许可证的概念，ＴＤＰ的理论研究和实践应用，排污交易政策在美国的发展等。美国的排污交易政策由补偿政策、气泡政策、净得政策和排污银行４项组成，以美国酸雨计划为例说明了排污交易的巨大环境经济效益，并给出了建议。     

重庆市污染源结构对大气SO_2浓度贡献的数值分析

运用三维欧拉传输、转换、迁移模式对重庆城区各种大气污染源对大气ＳＯ２浓度的贡献数值进行模拟，分析重庆城区ＳＯ２污染形成的原因。结果表明，民用源和低矮工业源对地面ＳＯ２污染浓度贡献最大，而中高架源则主要影响高层大气，是高空大气污染及酸雨形成的重要原因。     

汽车代用燃料及应用前景

介绍了已经开发使用的代用燃料氢气，甲醇，乙醇，新配方汽油，天然气，液化石油气，电动汽车等，并对代用燃料车和汽油车的环境安全性，成本，能耗消耗等方面作了比较，指出天然气，液化石油气是当前最有前途的代用燃料。     

关于温室气体限排目标的确定（巴西提案）

巴西提案是巴西代表团在联合团气候变化谈判中，提出的一套系统的全新的对中国家有利的理论体系，文章在对巴西提案中的有效排放量、简单气候模式、斐和限额分配方法、消沽发展基金等，进行深入睥评价的基础上，提出应将有效排放量与人均排放量与有机结合， 交圾效人均排放量曙室气体限排目标的指标。     

总量控制目标与环境影响评价的探讨

根据实施主要污染物总量控制，对环境影响评价提出的新课题，探讨了其在评价范围、评价标准、参与方式和评价内容上的变化；据此，结合总量控制的环境影响评价工作程序以及给涉及环评的有关部门带来的新要求，提出了见解。     

捷达车实测排放因子和MOBILE6预测值的对比分析

OEM是最新的基于车辆实际行驶路况的车载尾气检测系统，文中利用OEM在实际道路上对不同捷达车的实时尾气排放进行测量，得到10天测试车辆每秒的尾气排放数据，并利用数据库统计、排放数据匹配行驶周期等方法，计算出每天的平均尾气排放因子。同时使用了美国的MOBILE6软件，确定相对应的输入参数，得到相应排放因子。最终将两者进行比较分析，探讨MOBILE6在中国的适用性。