Max Planck Institutes and Experts

Novel in-situ mass spectrometric techniques offer new possibilities for the investigation of traffic related particle emissions. Measurements performed on an engine test facility showed that ultrafine particles (<100 nm) in diesel exhaust consist of freshly nucleated compounds as sulfuric acid and organics, which have been emitted as gaseous substances. Since it was found that the formation efficiency of these nucleation particles is strongly dependent on the fuel sulfur content, it was concluded that sulfuric acid plays a major role in this process. Measurements of mass concentrations and size distributions of various aerosol compounds in the vicinity of a German motorway and in New York City showed the various influences of traffic emissions on the composition of ambient aerosol in the different size ranges at different times.

Stable isotopes, in particular of nitrogen and carbon, are a new tool to study the structure of food webs in aquatic ecosystems. These isotopes show characteristic enrichment when organic material is passed from one step in the food chain to the next. Moreover, the isotopic composition of organisms provides information on the origin of their resources. Scientists in the Department of Physiological Ecology of the Max Planck Institute for Limnology used this method to show how carbon from methane produced in lake sediments is transferred through bacteria and midge larvae to spiders outside of the water. In another project, they were able to demonstrate that different morphotypes of the same fish species specialize on different habitat and food resources in a lake.

Earth system research is the science of global change, whether caused naturally or by humans. Earth system research requires the amalgamation of previously unrelated scientific disciplines and the appreciation of the Earth as a system of interacting compartments. In-situ measurements, satellite remote sensing, and numerical modelling are the pillars of Earth system research and have advanced dramatically in recent years. The Earth System Research Partnership is the association of the Max Planck Institutes dedicated to Earth system research, with further contributions by several Max Planck and other institutes.

Many environmental pollutants are slowly degrading (persistent) and very mobile. Results of simulations using a global multicompartment model which is based on an atmosphere general circulation model are presented. The integration of soils, vegetation, air, ocean and ice is mandatory in order to describe the environmental fate, i.e. transports and transformations, of slowly degrading and semivolatile substances. This class of substances includes the so-called persistent organic pollutants (POPs) and other pesticides and industrial chemicals. The investigations elucidate the combined effects of climate and substance properties on transport and distribution of pollutants and allow to quantify persistence and long-range transport potential.

Denitrifying microorganisms play a key role in the global nitrogen cycle. Denitrification is one of the main processes of this cycle and trace gases originating from it cause climatic effects. Application of molecular techniques in the field of microbial ecology allowed fundamental insights into diversity and structure of denitrifier communities. This is a prerequisite to understand the interrelationship of structure and function of denitrifier communities and the influence of parameters that drive the development of these microbial communities and their activity in the environment.