General Interests: I am interested in the trace gas chemistry of the atmosphere, the oceans, and large lakes
with emphasis on long-lived anthropogenic trace gases
and their use as tracers of fluid motion. I am also
interested in climatically relevant and biogeochemically active trace gases in particular the
cycling of these trace gases between the atmosphere, the technosphere, the oceans, and the biosphere.
This interest extends to a temporal variability
of these trace gases on inter-annual and decadal to centennial time scales.
Currently my research focus is on the atmospheric chemistry of 'Montreal' and 'Kyoto' Protocol
substances such as CFCs, HCFCs, and HFCs.
Ongoing and Past Activities:
One of my main current activities is the long-term observations of climate gases at the
high-altitude global GAW observatory at Jungfraujoch, Switzerland. Using most advanced gas-chromatography
mass spectrometry (Medusa) we are measuring a suite of trace gases that are climatically relevant. In particular,
we measure the Montreal Protocol species (CFCs, HCFCs) but also their replacement compounds, the hydrofluorocarbons (HFCs).
Among these are the recently introduced fluorocarbons (HFCs) HFC-245fa and HFC-365mfc in the world's foaming market,
for which we have captured their atmospheric onsets.
Another exciting ongoing project is SOGE-A
(System for observations of Greenhouse Gases in Europe and Asia).
This is a European-Chinese collaboration. For the first time, we are conducting quasi-continuous ground-based high-precision
measurements of halogenated compounds at the Chinese regional GAW station of Shangdianzi. The purpose of this project is to
conduct long-term measurements and to use these for estimating Chinese halocarbon emissions.
I am also involved in many smaller exciting atmospheric project, for example one involving the use of SF5CF3/SF6 as
deliberate-release tracers, which has now been applied to estimate ammonia emissions from cow stables.
Atmospheric molecular hydrogen (H2, mixing ratios and stable isotopes) has recently caught my interest, mainly because of
its potential future importance in a hydrogen energy economy.
A larger project that I am currently
managing is to build 4 state-of-the-art 'Medusa' GC-MS systems in collaboration with Chinese and Norwegian scientists. Some
of these instruments are planned for field installations at the end of 2009 in China and in Spitzbergen for the continuous
measurements of a suite of nearly 50 halogenated compounds (CFCs, HCFCs, HFCs).
Some of my other past activities in atmospheric science was the participation in a project that deals with the
response of the Eurasian continent to a rapid climate change . This is a
Max Planck Society project lead by the Max Planck Institute for Biogeochemistry in Jena.
Another activity in atmospheric sciences was concerned with the atmospheric
abundance of SF6, and
its temporal evolution. I made use of my high-precision analytical SF6 measurement technique and I have been
analyzing flask samples from the clean air monitoring sites at Cape Grim
and Trinidad Head. Using my analytical techniques for SF6 and CFC measurements I have been able to analyze
extremely low concentrations of SF6 and CFCs from firn air and ice air
samples. Based on these measurements we have been able to derive an estimate of the preanthropogenic abundance
of natural SF6 in the atmosphere. We have also collected air samples from the outgassing at the dormant
Mammoth Mountain volcano in Northern California. However the samples, which we collected through the 1m snow
layer in spring 2002, were 'too good', they contained up to 60% CO2 thereby creating instrumental difficulties
which didn't allow us to make accurate measurements the compounds we are interested in.
My activities in aquatic sciences include studies in limnology and
oceanography as well as research on old groundwaters. As part of my graduate studies
I have studied the renewal rates of the deepwaters in Lake
Malawi/Nyasa/Niassa and Lake Issyk-Kul using modern anthropogenic tracers (SF6, CFCs, tritium/helium).
Some of the work on Lake Malawi is ongoing and my interest in large lakes is still very high. My current
oceanographic activity is a Black Sea project which involved an
expedition to this marginal sea in spring 2003.
Past
oceanographic projects are the 1997 WOCE/ACCE A24 North Atlantic expedition
(transient tracer study) and some short trips in the Northeast Pacific (Ventilation of the Hydrate Ridge/
Eel River areas, methane gas hydrate studies). One of the most exciting activity has been the
study of naturally-occuring SF6 and carbon tetrafluoride
(CF4) in old groundwater.
(Update: 1/2009)
