LETTERS Werner Stumm: Environmental chemist, teacher, and advocate The extraordinary scientific career of Werner Stumm, spanning almost five decades, ended with his death in April of this year. His students and colleagues mourn his passing. He touched the lives of so many environmental scientists and engineers through his research leadership, his brilliant teaching, his extensive writings, and his personal concern for the well-being of his students and collaborators. He was a strong voice for the importance of environmental scientists and engineers joining in protecting the water environment, which he regarded as an endangered ecosystem. For Werner Stumm, the pursuit of a deeper understanding of the processes governing all natural water environments was a unifying theme of his life. He believed that information at the molecular level was needed to understand local, regional, and global aspects of elemental cycles and impacts of pollution. Professor Stumm took great pleasure in his studies of natural water systems. He drew upon his strong early background in solution chemistry and physical chemistry in order to attack problems. He received his Ph.D. with Ceroid Schwarzenbach at the University of Zurich in 1952. He discovered his interest in the water environment in his first job as a research chemist at the Swiss Federal Institute for Environmental Science and Technology (EAWAG). A postdoctoral year at Harvard University deepened his understanding of iron corrosion and calcium carbonate precipitation on surfaces. In 1956, he joined the Harvard faculty in environmental engineering and science. His delight in identifying and describing the chemical reactions underlying speciation and biological availability of trace elements, weathering rates of minerals, and more efficient methods for characterizing
water and wastewater was well known and admired by his colleagues. Paralleling his love of research into natural water chemistry was his great dedication and enthusiasm for teaching and mentoring young environmental scientists and engineers. Werner Stumm was extremely generous in giving his time and energy to students and colleagues interested in environmental research. His doctoral students and postdocs valued the challenging questions that he could be relied upon to raise concerning their research. He was "Doctor Father" to 43 Ph.D. students. In 1970, he returned to his native Switzerland, and during his 22 years as Professor at ETH and Director of EAWAG in Zurich, he guided the research of 33 Ph.D. students. Postdoctoral researchers in similar numbers went to Harvard and later to EAWAG to collaborate with Stumm. During his career, he authored or coauthored 300 research papers and produced 16 books. He authored 18 papers in the years following his retirement in 1992. Werner Stumm pioneered aquatic chemistry, which he introduced to the vocabulary of environmental science in 1967 in the Advances in Chemistry Series 67, Equilibrium Concepts in Natural Water Systems, a goal of which was "to stimulate research in aquatic chemistry." His conception of aquatic chemistry was that it would draw on basic chemical principles to arrive at a quantitative description of the processes that determine the composition of natural waters. He made substantial contributions to environmental chemistry, environmental engineering, geochemistry, limnology, oceanography, and other environmental sciences. His application of chemical principles to explain the composition of different natural waters followed in the tradition of van't Hoff, Arrhenius, Goldschmidt, and Sillen, among others. Stumm's studies of corrosion, coagulation, and filtration in water treatment systems enriched earlier chemical
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contributions by Tillmans, Langelier, Buswell, Larson, Black, and others. The early foundations of aquatic chemistry were found in acid-base chemistry, coordination chemistry, precipitation and dissolution equilibria, interphase transfer processes, oxidation-reduction processes, and surface chemistry. These were augmented over time to draw upon photochemical principles, rates of solid dissolution, and particle transport processes. During the last two decades of his career, Werner Stumm dedicated his research to the chemistry of interfaces. As director of EAWAG, Stumm shaped it along multidisciplinary lines, and it became a pre-eminent worldwide institution for the study of natural water science and engineering. He argued vigorously for an ecosystem approach toward protection of aquatic systems, integrating the study of chemical, geochemical, biological, and physical processes. He was awarded the Tyler Prize for Environmental Achievement in 1986. The study of the chemistry of the solid-water interface in relation to natural water systems is one of Werner Stumm's greatest scientific successes. From 1970 to 1992, he and his students demonstrated the major role that speciation at particle surfaces can play in trace element regulation, rates of mineral dissolution, oxidation-reduction reactions, and surface catalysis of electron transfer processes. Stumm's work at EAWAG was paralleled by similar research at the University of Bern by the coordination chemist Paul Schindler. They dubbed their companion works on surface chemistry the "Swiss Cheese Model" (tongue in cheek). It stimulated an enormous body of further research. Werner Stumm made many lasting contributions during his career. He also made a difference for many environmental scientists and engineers. His legacy will be cherished. JIM MORGAN California Institute of Technology
