Zum indirekten Photoabbau chlororganischer Verbindungen durch OH-Radikale in der Atmosphäre

The substituent chlorine is generally considered to be an agent which reduces the reactivity of organic molecules with regard to the indirect photodegradation by OH radicals. A systematic study of selected, representative classes of compounds, however, reveals that the deactivating influence of chlorine on the OH radical reactivity is actually rather moderate. In individual cases, for instance, chlorine substitution can even lead to an increase in this reactivity. This study is based on both experimental data and on the molecular orbital calculations of OH radical reactivity.     

Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system

Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net effects of climate change on terrestrial feedbacks to the climate system. This uncertainty applies to magnitude, and even direction of some of the feedbacks.     

A Survey Technique for Determining The Representativeness of Urban Air Monitoring Stations With Respect to Carbon Monoxide

An air quality survey technique for measuring the horizontal spatial variation of carbon monoxide concentrations in urban areas is described; it was used to determine how representative an urban air monitoring station is of concentrations throughout the city.

The survey technique was applied in San Jose, Calif., where 1128 samples were collected over a six-month period and were compared with the values recorded simultaneously at the urban air monitoring station. All samples were collected at “breathing height” within a 13-square-mile grid which included the downtown area as well as surrounding residential and industrial locations. Three basic sampling strategies were employed to answer specific questions about the distribution of carbon monoxide concentration: (7) walking sampling, in which samples were obtained while walking along the sidewalks of congested downtown streets, (2) random spatial sampling, in which samples were collected at randomly selected points in the urban grid, and (3) specialized sampling in the immediate vicinity of the air monitoring station.

The results indicate that pedestrians on downtown streets in San Jose can be exposed to concentrations above the federal air quality standards without these values being observed at the air monitoring station. There also is evidence that, at any instant of time, similar values of carbon monoxide exist throughout this city (within a 13-square mile area), provided that measurements are not made in close proximity to streets. Furthermore, the higher concentrations observed in the immediate vicinity of streets decrease quite rapidly with increasing horizontal distance from these streets.

These findings, in the view of the authors, raise serious doubts as to whether it is possible to determine if air quality standards as currently defined are actually being met in urban areas using data from present-day air monitoring stations.     

Betriebliche Umweltinformationssysteme (BUIS) Anforderungen und struktureller Aufbau

Appropriate organization structures, environmental controlling systems, and corporate environmental information systems (CEIS) are generally considered to be the essential instruments of a modern environmental management. Frequently, acceptance problems have been observed with respect to the installation of a CEIS due to the facts that there are no legal demands to implement such a system and, on the other hand, that theoretically based definitions of standards and structural principles of an CEIS are not yet available. As a consequence, different isolated solutions with rather low efficiency were hurriedly implemented by various companies. Regarding more precise request profiles for CEI systems, the present paper deals with the structural environment and the priority targets of an enterprise and with the organizational integration of environmental tasks. The operationalization into typical function fields yields tools to derive rough enterprise models, to analyze information streams and to select enviromentally relevant information as well as the routes which they tend to go. Based on these fundamental instruments, a CEIS architecture (structure and organization) can be developed whose realization is eventually supported by a ten-step plan. Existing EDP solutions are deliberately excluded in order to verify the general validity of the system architecture and to encourage creative potentials. The CEIS concept presented here, however, requires a transformation into operative practices, i.e. adjustment, completion, and combination of the elements concerning the detailed conditions of the enterprise under study.     

A prospective study on rapid exome sequencing as a diagnostic test for multiple congenital anomalies on fetal ultrasound

Objective

Conventional genetic tests (quantitative fluorescent-PCR [QF-PCR] and single nucleotide polymorphism-array) only diagnose ~40% of fetuses showing ultrasound abnormalities. Rapid exome sequencing (rES) may improve this diagnostic yield, but includes challenges such as uncertainties in fetal phenotyping, variant interpretation, incidental unsolicited findings, and rapid turnaround times. In this study, we implemented rES in prenatal care to increase diagnostic yield.

Methods

We prospectively studied 55 fetuses. Inclusion criteria were: (a) two or more independent major fetal anomalies, (b) hydrops fetalis or bilateral renal cysts alone, or (c) one major fetal anomaly and a first-degree relative with the same anomaly. In addition to conventional genetic tests, we performed trio rES analysis using a custom virtual gene panel of ~3850 Online Mendelian Inheritance in Man (OMIM) genes.

Results

We established a genetic rES-based diagnosis in 8 out of 23 fetuses (35%) without QF-PCR or array abnormalities. Diagnoses included MIRAGE (SAMD9), Zellweger (PEX1), Walker-Warburg (POMGNT1), Noonan (PTNP11), Kabuki (KMT2D), and CHARGE (CHD7) syndrome and two cases of Osteogenesis Imperfecta type 2 (COL1A1). In six cases, rES diagnosis aided perinatal management. The median turnaround time was 14 (range 8-20) days.

Conclusion

Implementing rES as a routine test in the prenatal setting is challenging but technically feasible, with a promising diagnostic yield and significant clinical relevance.     

Modeling eelgrass spatial response to nutrient abatement measures in a changing climate

For many coastal areas including the Baltic Sea, ambitious nutrient abatement goals have been set to curb eutrophication, but benefits of such measures were normally not studied in light of anticipated climate change. To project the likely responses of nutrient abatement on eelgrass (Zostera marina), we coupled a species distribution model with a biogeochemical model, obtaining future water turbidity, and a wave model for predicting the future hydrodynamics in the coastal area. Using this, eelgrass distribution was modeled for different combinations of nutrient scenarios and future wind fields. We are the first to demonstrate that while under a business as usual scenario overall eelgrass area will not recover, nutrient reductions that fulfill the Helsinki Commission’s Baltic Sea Action Plan (BSAP) are likely to lead to a substantial areal expansion of eelgrass coverage, primarily at the current distribution’s lower depth limits, thereby overcompensating losses in shallow areas caused by a stormier climate.     

Intra-industry trade in intermediate products, pollution and internationally increasing returns

This paper examines the relationship between intra-industry trade in intermediate products, pollution and increasing returns. We develop a two-country model in which production occurs in two stages, final and intermediate good production. Intermediate goods are produced under monopolistic competition and final good production exhibits increasing returns with respect to the number of varieties of intermediates. Pollution occurs in the production of the final good when polluting intermediates are used. We analyze the effects of international trade in intermediate products on pollution, output and welfare under an endogenous tax scenario and with two types of pollution functions. The results show that, because of increasing returns, international trade either leads to lower total pollution in each country or lower pollution per unit of output in at least one country. In addition, intra-industry trade causes countries to import the environmental quality of their trading partners.     

Studies of the oxidative photoinduced degradation of silicones in the aquatic environment

During irradiation of aqueous solutions of a mixture of oligomeric dimethylsiloxanes with artificial sunlight in the presence of nitrate ions, a reduction in the concentration of the siloxanes was demonstrated. This was verified by atomic absorption spectroscopy and proton nuclear magnetic resonance spectroscopy.In two separate tests, average halflives of 9 and 4 days, respectively, were determined after extraction of the aqueous solutions and analysis by atomic absorption spectroscopy.Silicate was demonstrated to be the final photodegradation product of these water soluble siloxanes. Photometric determination of silicate after 35 days showed nearly complete transformation, based on the original quantity of siloxanes.When an aqueous emulsion of high molecular-weight poly(dimethylsiloxane) was irradiated in the presence of nitrate ions under similar experimental conditions, a level of silicate corresponding to 1.7% of the original quantity of poly(dimethylsiloxane) was found after 5 weeks.