Methyl tert-butyl ether (MTBE) in urban and rural precipitation in Germany

The use of the oxygenate methyl tert-butyl ether (MTBE) in gasoline has led to detectable concentrations in urban and rural air up to 160 ppbV. Results from MTBE measurement in precipitation have not been reported so far. In the present study, 120 samples of precipitation collected at 17 sampling locations all over Germany have been analyzed for their MTBE content. Analysis is performed by a combination of headspace-solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC-MS). A 75 μm poly(dimethylsiloxane)/Carboxene fiber and a cryostat is used for SPME. The detection limit is 10 ng/l. In precipitation samples, MTBE was detected in wintertimes only with a maximum concentration of 85 ng/l. Measurement at Frankfurt/M City from 6 September 2000 to 12 March 2001 provided for 49% of the data concentrations in the range of 30–85 ng/l (n=17). Sampling in winter 2000/2001 at several German cities and rural locations showed that MTBE is more often detectable in urban (86%, n=78) than in rural (18%, n=42) precipitation. By comparing the results with corresponding temperatures and amounts of precipitation it can be concluded that the detection of MTBE in urban precipitation is observed at ambient temperatures lower than about 10–15°C. Moreover, the first precipitation after a dry period accumulates more MTBE than precipitation during or at the end of a wet period (wash-out effect). Highest concentrations occurred in snow samples. Corresponding mean air equilibrium concentrations of 0.04 ppbV (urban samples) and 0.01 ppbV (rural samples) are calculated. This is about one magnitude lower than year round and summertime measurements in the US and in Switzerland. Urban runoff (n=12) and corresponding precipitation sampling indicate that urban runoff might be composed of about 20% MTBE that is already transported by air and precipitation, whereas about 80% may be attributed to direct uptake of vehicle emissions and leakage near the road during precipitation.     

电生成羟基自由基及其对染料降解脱色的研究

以电化学循环伏安法和红外光谱分析 (IR) ,研究了茜素红及酸性铬蓝在电解槽中处理前后的电化学行为的变化 ,进一步阐明Fenton试剂的作用机制。电解生成的过氧化氢与阳极溶解的Fe2+ 进行随后反应 ,生成羟基自由基 (Fenton试剂 ) ,进而对有机染料进行氧化反应 ,使其不饱和的—N＝N—双键断裂 ,分解成萘胺与氨基苯酚磺酸两个部分 ,从而达到有机染料降解、脱色的效果。测试结果表明 ,电解处理15min内 ,脱色率和COD_cr的去除率变化较大 ,电解处理 1h ,COD_cr的去除率达 80 % ,脱色率达 98%.      

水质条件对膜-羧基官能团之间微观作用力的影响特征

为了探讨pH值、离子强度及膜材料对膜-污染物间相互作用力的影响特征,利用自制的典型膜污染物羧基官能团胶体探针,结合原子力显微镜定量考察了羧基官能团与PVDF及EVOH超滤膜间的相互作用力随pH值及离子强度的变化特征.结果表明:带有羧基基体的污染物与PVDF及EVOH超滤膜之间的相互作用力皆随着pH值的增大而减小;但是上述作用力随着离子强度的增加呈现特殊的变化趋势:在离子强度为0~10mmol/L时,膜-带有羧基基体的污染物之间相互作用力随着离子强度的增加而增大;在离子强度为10~500mmol/L时,膜-羧基之间相互作用力随着离子强度的增大而减小.在特定的水质条件下,EVOH-羧基间的作用力远小于PVDF-羧基之间的作用力.     

EFFECTS OF LAND COVER AND GEOLOGY ON STREAM CHEMISTRY IN WATERSHEDS OF CHESAPEAKE BAY1

ABSTRACT: We measured the base‐flow stream chemistry in all the major physiographic provinces of the Chesapeake Bay drainage basin. The spatial variation of stream chemistry was closely related to differences in geology and land cover among the sampled watersheds. Some stream chemistry variables were strongly affected by geological settings in the watersheds while others were more influenced by land cover. The effects of land cover differed among chemical constituents and regions. Concentrations of Ca²⁺, Mg²⁺, pH, total alkalinity, and conductivity were mainly functions of carbonate bedrock, especially in the Great Valley. Nitrate‐N and total dissolved N were closely related to cropland and increased as the percentage of cropland increased. The rate of increase varied from region to region with the highest in the Piedmont. Na⁺ and Cl^? were mainly affected by the percentage of developed area in a watershed, especially in the Coastal Plain and Piedmont. We observed no significant effects of region or land cover on species of phosphorus because samples were collected under base flow conditions and only dissolved forms were measured. Dissolved silicate (DSi) was not related to any other water chemistry variables. DSi increased as developed area decreased and cropland increased in the Coastal Plain, but these patterns were reversed in the Piedmont. There was no consistent pattern in the spatial variation of land cover effects on the reduced forms of N, dissolved organic P, dissolved organic matter, and K⁺.     

土壤吸附菲的灰色关联分析

在分析吸附机理研究方法的基础上,提出了一种判别吸附机理与模型的新方法.从影响吸附的诸因素入手,用灰色关联分析方法计算了不同颗粒粒径(26.9～38.9 μm)、SOC(8.85～17.15mg/g)和CEC(12.49～38.74 cmol/kg)的6种土壤吸附菲的反应中,SOC、CEC及颗粒粒径对吸附量的影响.结果表明,各影响因素的重要性顺序为:颗粒粒径＞SOC＞CEC;表面吸附理论是土壤吸附菲的主要吸附机理,分配理论次之.还讨论了描述此反应的吸附模型,认为多端元反应模型能较好地解释土壤吸附菲的反应.最后得到了一种判定土壤对有机污染物吸附机理与模型的数学方法,对机理研究有一定的指导意义.     

汉江上游金水河流域河水的化学特征

本文以汉江上游金水河流域为研究区域,通过对大气降水、河水的水化学及氢氧稳定同位素分析,揭示河水水化学特征及其补给来源.结果表明,(1)流域内大气降水和河水的水化学类型为Ca2+-HCO3-型,主要占优势的阴阳离子分别为HCO3-和Ca2+;(2)河水水质总体表征良好,其离子、金属及微量元素和营养盐的含量较低;(3)河水的δD和δ18O关系表明,河流的主要补给来源为大气降水.     

石油化工装置火灾灭火救援力量需求计算模型

消防用水流量的确定是灭火救援力量需求分析的关键,也是准确调集力量到达火灾现场实施灭火救援的前提和基础。针对《石油化工企业设计防火规范》(GB50160-2008)对石油化工装置消防用水流量的规定存在比较宽泛和模糊的问题,借鉴国外的一般做法,通过分析化工工艺装置的火灾危险性,确定石油化工装置的火灾爆炸危险性等级;再根据火灾爆炸危险性等级和装置的规模,分级确定石油化工装置一次灭火的消防用水流量;进而建立了一种基于火灾爆炸危险性分析的石油化工装置灭火救援力量需求计算模型。该模型的建立为科学准确地调集石油化工装置火灾灭火救援力量提供了重要决策依据。     

A Comparison of Loch Chemistry from 1955 and 1999 in the Cairngorms,N.E. Scotland

The Cairngorms in north-east Scotland is remote from pollutant sources although it currently receives ca. 10 kg ha¹ yr¹ S and ca. 11 kg ha¹ yr¹ N deposition from the atmosphere.In 1955, 15 lochs (lakes) at a range of altitudes were sampled and analysed for major ion concentrations. A new survey of these and an additional 23 lochs and their catchment soils was conducted in 1999 to determine the impact of acid deposition, and the changes in loch chemistry since the 1955 survey. The bedrock geology of this region has a strong influence on the loch chemistry. Surface waters were generally more acidic in high altitude areas due to predominantly poorly buffered, thin alpine soils developed on granitic parent material (mean acid neutralising capacity (ANC) for 23 lochs = 30 eq L¹). At lower altitudes where the geology is dominated by Dalradian metamorphic rocks surface waters are comparatively base rich and have higher ANC (mean ANC for 15 lochs = 157 eq L¹). Surface water nitrate concentrations show a negative relationship with soil C:N status, in that higher nitrate only occurs at low soil C:N ratios. A comparison of data for 1955 and 1999 shows that sulphate concentrations are significantly lower (67.8 and 47.5 eq L¹, respectively), and pH has improved (pH 5.6 and 5.9) in response to decreased S deposition since the mid 1970s. However, mean nitrate concentrations were found to increase from 2.48 >eq L¹ in 1955 to 5.65 eq L¹ in 1999. Differences in the sampling and laboratory methods from 1955 and 1999 are acknowledged in the interpretation of data.     

A kinetic study of phenol nitration and nitrosation with nitrous acid in the dark

We studied the transformation of phenol in the presence of nitrous acid in the dark. The main detected intermediates were 2-nitrophenol, 4-nitrophenol and 4-nitrosophenol. For the first time a kinetic analysis of the reaction in a pH interval relevant to environmental chemistry has been carried out. The kinetic data are consistent with phenol transformation being initiated by HNO₂. The results are relevant to the chemistry of the atmosphere, where HNO₂ forms upon heterogeneous conversion of ^·NO₂, and to water treatment techniques.     

The U.S. Experience in Promoting Sustainable Chemistry (9 pp)

- Sustainable chemistry - Section editors: Klaus Günter Steinhäuser, Steffi Richter, Petra Greiner, Jutta Penning, Michael AngrickBackground, Aim and Scope Recent developments in European chemicals policy, including the Registration, Evaluation and Authorization of Chemicals (REACH) proposal, provide a unique opportunity to examine the U.S. experience in promoting sustainable chemistry as well as the strengths and weaknesses of existing policies. Indeed, the problems of industrial chemicals and limitations in current regulatory approaches to address chemical risks are strikingly similar on both sides of the Atlantic. We provide an overview of the U.S. regulatory system for chemicals management and its relationship to efforts promoting sustainable chemistry. We examine federal and state and examine lessons learned from this system that can be applied to developing more integrated, sustainable approaches to chemicals management.Main Features There is truly no one U.S. chemicals policy, but rather a series of different un-integrated policies at the federal, regional, state and local levels. While centerpiece U.S. Chemicals Policy, the Toxic Substances Control Act of 1976, has resulted in the development of a comprehensive, efficient rapid screening process for new chemicals, agency action to manage existing chemicals has been very limited. The agency, however, has engaged in a number of successful, though highly underfunded, voluntary data collection, pollution prevention, and sustainable design programs that have been important motivators for sustainable chemistry. Policy innovation in the establishment of numerous state level initiatives on persistent and bioaccumulative toxics, chemical restrictions and toxics use reduction have resulted in pressure on the federal government to augment its efforts.Results and Conclusions It is clear that data collection on chemical risks and phase-outs of the most egregious chemicals alone will not achieve the goals of sustainable chemistry. These alone will also not internalize the cultural and institutional changes needed to ensure that design and implementation of safer chemicals, processes, and products are the focus of the future. Thus, a more holistic approach of ‘carrots and sticks’ – that involves not just chemical producers but those who use and purchase chemicals is necessary. Some important lessons of the US experience in chemicals management include: (1) the need for good information on chemicals flows, toxic risks, and safer substances.; (2) the need for comprehensive planning processes for chemical substitution and reduction to avoid risk trade-offs and ensure product quality; (3) the need for technical and research support to firms for innovation in safer chemistry; and (4) the need for rapid screening processes and tools for comparison of alternative chemicals, materials, and products.