She later completed a master's degree in Environmental Sciences (1983) and Habilitation Geochemistry (1992) at Université Libre de Bruxelles.
[1] In this role, she published "High‐precision isotopic characterization of USGS reference materials by TIMS and MC‐ICP‐MS" in the journal Geochemistry, Geophysics, Geosystems.
[9] Weis' innovative use of trace element and isotopic geochemistry spans a wide range of applications in the Earth and environmental sciences.
This includes defining the source and evolution of igneous and metamorphic rocks, the interactions between different reservoirs (mantle, crust and atmosphere) and the role of tectonic settings.
Other interests include geochemical and isotopic studies of sedimentary rocks, global changes and reconstitution of past environments; distribution of pollutants in natural and anthropogenic systems; application of non-traditional heavy stable to environmental issues and analytical technique developments, techniques for high precision chemical and isotope analysis.