LFU:online

- Der Kurs vermittelt einen detaillierten Überblick über die chemischen Reaktionen, die die Konzentrationen von Schlüsselspezies in der Atmosphäre kontrollieren; kein Vorwissen in Atmosphärenchemie ist nötig.

- Fokus ist “schnelle Photochemie”, und die zugrundeliegende physikalische Chemie, die die katalytische Radikal Chemie, Ozon und Schadstoff Konzentrationen kontrolliert.

- Themen mit hohem wissenschaftlichen Interesse und Sozialrelevanz in Bezug auf den menschlichen Einfluss auf Luftqualität und Klima werden behandelt: Urbane Luftchemie, Feinstaub, und Chemie-Klima Kopplung.

- Ein Schwerpunkt des Kurses liegt in der Integrierung der neuesten wissenschaftlichen Studien in das Verständnis der Spurenstoffe in der Troposphäre (sekundäre Schadstoffe und Treibhausgase; behandelte Themen sind Bildung neuer Partikel und Wolkenbildungskeime einschließlich “Isopren-Unterdrückung, Rolle der Viskosität von Aerosolen, Limitierungen des Verständnisses der oxidativen Kapazität der Atmosphäre, Autooxidationschemie, die in schnellen chemischen Prozessen resultiert, Rolle von Wasser in Aerosolchemie.

In diesem Kurs werden die wichtigsten Aspekte der Chemie der Troposphäre aufgebaut ohne dass Vorwissen in diesem Bereich erforderlich ist. Ziel des Kurses ist Verständnis der chemischen und physikalischen Prozesse der Troposphäre zu entwickeln. Der Fokus liegt in Prozessen die Emissionen in sekundäre Schadstoffe, die Umwelt, Gesundheit und Klima beeinträchtigen, umwandeln, insbesondere in Bezug auf anthropogenen Einfluss. Nachdem die Grundlagen etabliert sind, wird evaluiert, wie die neusten Studien unser Verständnis der besprochenen Prozesse beeinflusst.

The first part of the course will generate a framework of tropospheric chemistry. After that three topics will be discussed in more detail:

Topic 1: Impact of recently discovered auto-oxidation/auto-catalysis

Recently discovered atmospheric auto-oxidation reactions of hydrocarbons are changing our understanding of how secondary pollutants, in particular secondary organic aerosol, and new particles are formed. After an initial oxidation reaction molecules undergo a number of internal reactions that rapidly increase the oxygen content of the molecules, which affects their physical and chemical properties, and also has direct implications for our understanding of the oxidative capacity of the atmosphere. The rapid oxidation, compared to a slower, step-wise mechanism represents a fascinating chemical system that is changing our understanding of tropospheric oxidation with direct implications for the environment.

Topic 2: Implications of the physical state of atmospheric aerosol:

In the last years “glassy” atmospheric aerosol (aerosol = fine particulate matter suspended in air) has received intense study. The term refers to aerosol with very high viscosity. It is important to fully understand this phenomenon, which has a strong dependence on humidity and temperature. Diffusion in high viscosity aerosol can be extremely slow, preventing equilibration, e.g., with the gas-phase, and effectively trapping molecules inside the aerosol. The viscosity state of aerosol impacts environmentally important aerosol properties, such as the amount (mass) of aerosol, chemical and, in particular, physical properties, all of which impact the environment ranging from health to climate effects. “Glassy” aerosols represent another fascinating system in which fundamental physical and chemical processes have direct implications for the environment.

Topic 3: The role of aqueous (aerosol) chemistry:

(Secondary) organic aerosol, (organic aerosol formed in the atmosphere and not directly emitted) plays an important role in the environment as it affects climate and human health. However, the physical and chemical processes of OA formation remain poorly understood. Traditional aerosol studies were conducted almost exclusively under dry conditions, largely as this is experimentally much easier. Clearly, reactions in water can follow different pathways than in organic solutions. Furthermore, some molecules will be highly soluble in water but not in organic solutions. In recent years aqueous aerosol - in contrast to dry aerosol only consisting of organic compounds and inorganic salts – has therefore received a lot of attention. However, unambiguous evidence for the importance of aqueous aerosol remains elusive. This topic will explore to which degree evidence for the role of aqueous chemistry in controlling important physical and chemical aerosol properties has been uncovered and discuss what experiments are needed.

Class presentation: Each student will give one 20-minute lecture to the class on a current atmospheric chemistry technique or approach (measurement/modelling). These will be given throughout the semester, with the specific topic related to that day’s lecture. Intended as an overview of the subject, with citations from the recent literature. Topics/schedule determined in the second week of class.

Die meisten Texte werden aus aktueller Literatur ausgewählt.

Nützliche Lehrbücher:

• Jacob, Introduction to Atmospheric Chemistry, (Princeton, 1999); Text online erhältlich (http://acmg.seas.harvard.edu/people/faculty/djj/book/index.html)

• Seinfeld and Pandis, Atmospheric Chemistry and Physics, 2^nd ed. (Wiley, 2006) 1^st edition okay, obwohl Seitenzahle unterschiedlich sind.

• Finlayson-Pitts and Pitts, Chemistry of the Upper and Lower Atmosphere (Academic Press, 2000)