Friedrich Schwille: an historical appreciation.

In 1675, Isaac Newton wrote to Robert Hooke, his fellow physicist, ‘‘If I have seen further it is by standing on the shoulders of giants.’’ This Historical Note posthumously honors one particular giant, Friedrich Schwille, who died on April 15, 2000, in Koblenz, Germany. He is survived by his wife Margret and two children—Martin and Christine—and their families. Friedrich Schwille (Figure 1) was born in Neckartailfingen (a small town in southern Germany near Stuttgart) on March 4, 1920. He grew up there and graduated high school (i.e., gymnasium) in nearby Reutlingen in 1938. During World War II, he was a mountain soldier in the German Army and was injured during fighting in the Caucasus in 1942 and repatriated. He entered the University of Tübingen in 1945 and later the Technical University of Darmstadt and completed the Diploma in Geology (M.Sc.) in 1949 and the Ph.D. in Geology in 1950. He joined the Geological Survey of the RheinlandPfalz as a hydrogeologist in 1953, and in 1960 became chief hydrogeologist of the Federal Institute of Hydrology in Koblenz. Because this institute was part of the Federal Ministry of Transport, it had particular responsibility for the construction and maintenance of the German waterway system, hence its location where the Mosel River enters the Rhine. Schwille’s early work in the Federal Institute focused on the effects of fuel hydrocarbons, i.e., light non–aqueous phase liquids, on ground water quality. Schwille developed an innovative experimental approach of using glass-lined tanks (Figure 2) to study the migration and fate of immiscible liquids in ground water. Schwille (1975) presented the results of this work at the 1971 IAHS Symposium on Groundwater Pollution in Moscow. Those familiar with his later studies of dense non–aqueous phase liquid (DNAPL) will find in this paper many similar themes such as the importance of the volume of fuel released, trapping in the vadose zone, retention capacity, migration of dissolved components, gaseous migration, and the need for integrated studies involving many disciplines. He also drew attention to the importance of water table fluctuations in developing the ‘‘smear zone.’’ His first trip to North America was probably in 1975 to present a paper on the nature of reduced ground water at the International Symposium on the Geochemistry of Natural Waters, which was held at the Canada Centre for Inland Waters in Burlington, Ontario. Again, he was far ahead of his time in looking at the effects of oxygen depletion on the biogeochemistry of ground water, a topic that is at the forefront of our concern with growing interest in monitored natural attenuation. In this paper, he outlined the general nature of the redox zonation of ground water and summarized European research on this topic. In the early 1980s, Friedrich Schwille and his colleagues at the Federal Institute of Hydrology in Koblenz developed the conceptual model of the migration and fate of DNAPL (Schwille et al. 1984). Their 1984 report on laboratory experiments of the migration and fate of dense chlorinated solvents established the principal features of the DNAPL paradigm, including rules and experiments that hydrogeologists and others would subsequently follow. Specifically, they showed the patterns of migration and trapping of solvents in sands of various particle sizes and the retention of this DNAPL by these same sands above and below the water table. Furthermore, they demonstrated the solubilization of the DNAPL to form dissolved-phase plumes and the importance of the volume of solvent spilled and the geometrical arrangement of zones of differing permeability in determining the spatial distribution of DNAPL in the subsurface. The DNAPL paradigm, therefore, identified the spreading, trapping, and dissolution phenomena that characterize the migration and fate of chlorinated solvents in the subsurface and the fate of dissolved and vapor phases. While most of the 1984 report referred to granular aquifer materials, he also devoted one chapter to DNAPL spreading in fractured or karstic media. This report was translated into English by Pankow (Schwille et al. 1988), although elements of the paradigm appeared in English in Schwille (1981) and more completely in Schwille (1984). In many ways, Schwille anticipated the problems contaminant hydrogeologists would INTERA Inc., Niwot, CO 80544; [email protected] Copyright a 2006 The Author(s) Journal compilationa 2006National GroundWater Association. doi: 10.1111/j.1745-6584.2006.00209.x