Harmful Nitrogen Compounds in the Atmosphere
A Pressing Environmental Problem
Caption: Current levels of ammonia emissions from agricultural activities are much too high, and must be reduced – for example by the systematic use of low-emission techniques for spreading liquid manure. | |||
In 2008 Switzerland emitted only about half the amount of nitrogen-containing pollutants as it did at the end of the 1980’s. Enough reason to be complacent? “Not at all!” says Empa physicist Christoph Hueglin. Nitrogen oxide concentrations are still too high, above all in towns and cities and along major traffic routes. This is shown by measurements made by the National Air Pollution Monitoring Network (NABEL), which Empa operates in conjunction with the Swiss Federal Office for the Environment (FOEN). Nitrogen oxides, which are produced during the burning of fuels, among other processes, are damaging to human health, as are other pollutants such as ozone and fine particulates, in that they can encourage diseases affecting, for example, the respiratory organs. | |||
A global problem | |||
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| Nitrogen oxide concentrations are still too high, above all in urban areas and along major traffic routes. | ||
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And it is precisely when dealing with nitrogen oxide emissions by motor vehicles that significant improvements can be achieved thanks to effective technical measures. Through the systematic implementation of emission reducing technologies, such as catalytic converters based on ceramic foams (developed at Empa), it should be possible to solve the problem within the foreseeable future, according to Christian Bach, Head of Empa’s Internal Combustion Engines Laboratory. | |||
In addition to their disreputable role as precursor compounds in the generation of ozone and fine particulates, nitrogen oxides also have damaging effects on agriculture. True, ammonia was originally held in high regard in the 19th century as the raw material from which many chemical products could be made (including synthetic fertilizers) and as such vaunted as an important agent in the battle against hunger. Fertilizers did indeed mean improved harvests, but the nitrogen compounds they contained caused acidification and eutrophication (over-fertilization) of the soil. Among the other consequences, not least were the negative effects on the balance of greenhouse gas emissions and associated ecosystems. Albrecht Neftel of the Agroscope Reckenholz-Taenikon Research Station ART explained how these ecosystems are currently being investigated in the «NitroEurope» European research project. It is vitally important that we drastically reduce agricultural ammonia emissions, which are far too high – for example by using low-emission spreading techniques for liquid manure application to fields. Despite the fact that some reduction measures are already implemented, ammonia emissions from agricultural activities in Switzerland and large areas of Europe remain stubbornly unchanged at excessively high levels. | |||
Emissions must be halved | |||
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| Powerful analytical measuring instruments are required to undertake the extremely complex investigations of air pollutant chemistry. One example is the new quantum cascade laser spectrometer developed at Empa, which uses new spectroscopic methods. | ||
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Für diese äusserst komplexen Untersuchungen der Luftschadstoffe sind leistungsstarke analytische Messtechniken gefragt – zum Beispiel neue spektroskopische Methoden wie das von Empa-Forscher Lukas Emmenegger entwickelte Quantenkaskadenlaser-Spektrometer, das sehr schnelle und empfindliche Analysen ermöglicht und sogar verschiedene Lachgas-Isotope (N2O) unterscheiden kann. Dadurch lassen sich emittierte Lachgasmoleküle aus Verbrennungsprozessen in Kraftwerken von «biologisch produzierten» N2O-Molekülen aus Kläranlagen unterscheiden. To undertake such extremely complex investigations, high performance analytical measuring instruments are required. One example of such an instrument using new spectroscopic techniques is the quantum cascade laser spectrometer developed by Empa researcher Lukas Emmenegger. This device is capable of rapid and very sensitive analyses, and can even differentiate between isotopically different kinds of N2O (nitrous oxide, also known as laughing gas). This means that it can separate nitrous oxide emissions sourced from combustion processes and “biologically produced” N2O emissions from sewage treatment works. | |||
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