Naturally produced halogen compounds are the central subject of our research unit.
Produced in, and released from soils, salt surfaces, and aerosols, they are of utmost importance for stratospheric
and tropospheric chemistry. Examples are
- CH3Cl, CH3Br for stratospheric ozone depletion
- Br2, BrCl for the
bromine explosion in the polar boundary layer
- I2, CH3I, CH2I2
for reactive iodine chemistry, leading to
new particle formation.
These compounds may pose a hazard to terrestrial ecosystems, which has already been shown for
halogenated carbonic acids such as
The reaction mechanisms prevailing in natural halogenation processes in soil and on aerosols are similar
from the viewpoint of reaction products, pointing to a chemistry where free radicals are involved.
Radical reactions may be induced by
redox-sensitive elements, like iron and/or oxygen,
and organic molecules in soils or on aerosols (as humic
substances and humic-like substances)
- or by photochemistry of molecules like
X2, HOX, OH (where "X" is a halogen or pseudohalogen),
with humic substances as a
photosensitizer, on atmospheric particles.
To address the key open questions, a combined effort of scientists from biogeosciences and atmospheric
science is required. Scientific work groups on the following research fields are
- Atmospheric chemistry
- Inorganic chemistry
- Coordination chemistry
- Environmental physics
- Environmental chemistry
- Meteorology, and
- Physical chemistry.
Our approach is threefold:
Laboratory studies on a molecular level, starting from model compounds to
the complex organic material of soils and aerosols, are conducted in batch systems and in an aerosol smog
- Field campaigns deliver the "real world" constraints for the laboratory studies and serve as test
sites for the laboratory results.
- Atmospheric modelling studies help to combine the results gained in
laboratory experiments and field observations and to assess the significance of the investigated