9.12.1917 (Bredkälen, Sweden) -
Erik Eriksson was born on 9 December 1917 in a small village, Bredkälen, in the northern part of Sweden, where his parents had a small farm. After 6 years of primary school he worked for 10 years at the farm during summer and as a woodsman in winter. Preparing for a future profession as a farmer he attended a six months course at a farming school in 1937/1938. With the desire to know more, and supported by one of his teachers, he applied for The Special High School for Students in Agriculture, Forestry and Diary (Vilan, Åkarp) from which he graduated in 1942, after two years of study. After military service he began studying at Royal Agricultural College of Sweden in Uppsala (later included in Swedish Agricultural University, SLU) in 1943. He later commented this as “My life as a farmer ended there”.
Now he aimed toward being a senior advisor to farmers, taking courses in agricultural chemistry, soil science, botany, physics, mathematics, statistics, soil management, plant husbandry and hydrotechniques. During his studies he was appointed as assistant at the Department of Physics and Meteorology, later at the Department of Agricultural Chemistry (Prof. Hans Egnér), and finally at the Institute of Pedology (Soil Science, Prof. Sante Mattson) where he stayed for some years after having obtained the grade of agronomist in 1949. He became so absorbed in his new job that he “forgot all about the extension service which had been my original aim”. 1950/51 he spent one year at the Macaulay Institute for Soil Research in Aberdeen on a British Council scholarship and in 1952 he graduated Agronomie Licentiate in Soil Science.
In 1954 Professor Carl-Gustaf Rossby invited Erik Eriksson as an assistant at the Meteorological Department at Stockholm University. In 1957/1958 Eriksson spent one year in the US making research on sulfur isotopes in rainwater and atmospheric carbon dioxide circulation at the Institute of Zoology, Yale University (Prof. G. Evelyn Hutchinson), developing a method for tritium analysis in natural waters at the Department of Meteorology, University of Chicago (Prof. H. Byer), and working with data on sea salts in the atmosphere at Woods Hole Oceanographic Institution (Al Woodcock). In 1959 he received PhD grade with the thesis “Atmospheric transports of oceanic constituents in their circulation in nature” making him associate professor (docent). With a few leaves of absence for various missions he remained at the Meteorological department until 1970.
Erik Eriksson was responsible for the rainwater chemistry sampling in Project Shower, an international project on cloud physics in Hawaii in 1954. The aim of this project was to get insight into rainfall generating processes in a warm climate. In 1956 Erik Eriksson took part in an adventurous expedition with the Soviet icebreaker Ob in the Arctic, in which his mission was to make observations of atmospheric carbon dioxide between Greenland and Svalbard in order to better understand its exchange with sea water. Erik Eriksson and two Scandinavian and two Russian scientists happened to get stuck on the Vestfonna Glacier on Nordaustlandet, Svalbard, to which they were flown by helicopter for a short stay to make installations for glacier mass budget measurements. Due to a persistent fog and a helicopter accident they could not be flown back to the ship as planned and had to stay in a tent on the glacier for two weeks, waiting for rescue, without radio communication.
Erik Eriksson was invited by IAEA (International Atomic Energy Agency, formed in 1957) to an expert group on the peaceful use of isotopes, which initiated the setting up of the Global Network of Isotopes in Precipitation (GNIP) for sampling of tritium, oxygen-18 and deuterium in precipitation. During 1961 and 1962 he was employed as a Senior Officer at IAEA in Vienna, where he built up and led The Isotope Hydrology group, which later consolidated into The Section of Isotope Hydrology.
In 1970 he was invited to the just created professorship in Hydrology at Uppsala University, the first hydrology professorship in Sweden. He held this chair until his retirement in 1982 after which he continued research as professor emeritus. He also worked as a consultant, with Swedish projects, e.g., on the hydrologic effect of regulations for water power and international projects such as problems related to management of acidic soils in the Mekong delta.
Erik Eriksson was elected to The Royal Swedish Academy of Sciences in 1979.
Erik Eriksson is a generalist. He has daringly tackled scientific questions within a wide range of topics related to the circulation of water and matter, from the soil pore to the global scale. His production comprises theoretical works within soil physics, geochemistry, atmospheric chemistry, chemical oceanography, meteorology, hydrology and hydrochemistry. With his background as a farmer he had personal experience of many processes in nature and how to solve practical problems. In combination with curiosity and intellectual capacity this might have contributed to his ability to tackle problems within wide fields of research. With his broad knowledge and creativity, he could see problems from new sides, inspiring students and making valuable contributions to discussions in scientific meetings.
As a student he developed a method for analyzing ammonia in rain, which was later used in the atmospheric chemistry network. His first papers were on polarographic investigations of pyrophosphate complex (1948). His research at the Department of Soil science focused on the interaction between water and clay, including construction of an automatic instrument for differential thermal analysis of clays for identifying clay minerals and, with his own words, he “became so fascinated by the theory of heat flow in such instruments that it resulted in three papers filled with formulas of almost every conceivable kind but, presumably, hardly ever read!”
Erik Eriksson was a pioneer within atmospheric chemistry. In the early 1950s agricultural research saw the nutrient supply to soils from the atmosphere as a resource that needed to be understood and quantified. With this starting point he published papers on the composition of atmospheric precipitation and the global circulation of chemical compounds. Together with Rossby and Egnér he initiated a long-term atmospheric chemistry program, which developed into the European Atmospheric Chemistry Network (EACN) which became operational around 1955. Erik Eriksson made great contributions to the understanding of the global circulation of matter such as nitrogen, phosphorous, sulfur and chloride in the 1950s and 1960s. He analyzed the transport mechanism for sea salt particles from the oceans to the atmosphere by breaking waves and the wet and dry deposition over land areas, particularly of chloride and sulfur, and its effect in soils and on groundwater and streamwater composition. He showed the potential of using chloride as a hydrologic tracer, for instance for regional evaporation estimates.
The effect of carbon dioxide on atmospheric heating was well known in the 1950s, but the trend of increasing carbon dioxide was still considered uncertain due to lack of data, and the contribution from combustion of fossil carbon was debated. Erik Eriksson developed conceptual models for ocean mixing and global carbon flux and, based on equilibrium conditions for carbon dioxide pressure, he analyzed the possibilities for the ocean to act as a sink or a source for atmospheric carbon. In some cases he came to conclusions that today seem less probable. In 1956 he presented, together with Pierre Welander, a mathematical model of carbon cycle in the atmosphere-biosphere-sea and concluded that the observed increase in atmospheric carbon dioxide probably is a part of an oscillation on the time scale of several hundred years due to the feedback mechanism between assimilation by vegetation and atmospheric carbon dioxide. It was concluded that the injection of carbon dioxide from combustion of fossil carbon would increase the carbon in the biosphere, but only have a small effect on the atmospheric concentration. In a later paper, co-authored with Bert Bolin in 1961, the role of human supply by fossil carbon was, on the other hand, clearly shown. The forecasted increase in atmospheric carbon dioxide up to the year 2000 was remarkably similar to what now has been observed.
In an extensive paper on the conditions for glaciations, “Air-ocean-icecap interactions in relation to climatic fluctuations and glaciation cycles” (1968), Erik Eriksson suggests that historical changes in atmospheric carbon dioxide are not sufficient as an explanation for the dynamics of glaciations. From an analysis of the heat budget of the atmosphere and the earth’s surface he shows that variations in the solar constant could be the explanation, but he points out that there is no historical time series on solar data to test this hypothesis. According to his analysis there are possibilities for a “flip-flop” mechanism for rapid changes between equilibrium states for the extension of the ice-cap.
The increasing levels of tritium in the atmosphere, due to the hydrogen bomb testing starting in 1954, resulted in a growing interest among researchers for using tritium as a tracer in global circulation and hydrologic studies. Erik Eriksson was one of the pioneers in this and his most important achievement in hydrology, with a more limited definition of hydrology, lies within isotope hydrology. In “The possible use of tritium for estimating groundwater storage” (1958) he developed a method for interpreting tracer data from streamwater in terms of reservoir storage and distribution of transit times for groundwater. He introduced the exponential model for transit time distribution for a mixed reservoir in hydrology, and stressed that what from tracer data may look as the result of mixing during groundwater flow is caused by mixing in the streamwater of water with different flow path lengths and transit times in the groundwater zone. Methods for analyzing reservoirs with respect to ages and transit times were further developed in “Natural reservoirs and their characteristics” (1961), where reservoirs are classified and analyzed according to whether addition and subtraction boundaries are separated (e.g. groundwater/streamwater), the same (e.g. the ocean) or not possible to define (e.g. humus in a soil layer). The transit time distribution was estimated from an equation system which he pointed out was similar to the convolution integral, commonly used by later researchers in isotope hydrology. In “Atmospheric tritium as a tool for the study of certain hydrologic aspects of river basins” (1963) the theory was applied to tritium data for Ottawa river giving the result that about half of the discharging water had a transit time less than 3-4 years. The theories and concepts were further systematized in “Compartment models and reservoir theory” (1971).
In addition to the studies on how to get hydrologic information from environmental tracers, such as tritium, Erik Eriksson analyzed atmospheric transport processes for the tracers. Tritium transport in the atmosphere and the exchange of tritium between the atmosphere and land and ocean respectively were analyzed in “An account of the major pulses of tritium and their effects in the atmosphere” (1965). This contributed to the understanding of the global distribution of tritium in precipitation. In “Deuterium and oxygen-18 in precipitation and other natural waters, some theoretical considerations” (1965) atmospheric transport processes for these stable isotopes, much used in hydrology, were analyzed. The isotope fractionation plays a decisive role in labeling the vapor during this transport and Erik Eriksson’s analysis indicated a smaller fractionation coefficient when the transport is due to eddy motion than when the flow is purely advective.
One of Erik Eriksson’s research interests and expertise has been hydrochemistry. He has published papers and a text book (Principles and applications of hydrochemistry, 1985) on processes that create the chemical composition of groundwater, with special focus on weathering and conditions for equilibrium between mineral and water. From the 1970s to the 1990s there was an abundant research on the acidification problem in Sweden. With his broad knowledge Erik Eriksson played an important role in this research, e.g., with studies of the storage of sulfur in the soil and how it affects the time for recovery of acidified soils if acid deposition decreases.
Throughout his research Erik Eriksson has been interested in modelling and in mathematical treatment of problems. In 1970 he advocated the use of stochastic methods in hydrology for time series analysis and modelling, with two papers dealing with groundwater data from the Uppsala esker. He also showed in some reports the potential of using statistical methods for estimating errors in areal mean values and how statistical methods can be used in designing hydrological networks.
As professor in hydrology at Uppsala University Erik Eriksson inspired his students in discussions on streamflow generation and groundwater flow systems. From these discussions, and the related research, a view of streamflow generation in the Nordic till landscape was developed stressing the active role of shallow groundwater in the runoff process and the different hydrological functions of recharge and discharge areas for groundwater. Erik Eriksson’s main contribution to this was to inspire and give ideas and to teach his students to apply this generalized view to hydrological problems. He published one small conference paper “Groundwater recharge and surface runoff” (1977) where he showed the connection between groundwater recharge and the extension of the discharge area in an idealized hillslope. The developed view of streamflow generation and water flow paths was the hydrologic basis for his textbook in hydrochemistry, in which he treated chemical processes along the flow paths of water in detail, emphasizing the different processes in recharge and discharge areas and the different chemical conditions for young shallow groundwater and deep old groundwater.
To finish up this short review over Erik Eriksson’s professional life, two examples of his broad interests are given. The first example is his excursion into practical electronics in the 1970s, when he constructed instruments and dataloggers for recording temperature, electrical conductivity and water level for his and his students’ field experiments. He designed and soldered the electric circuits at home and built them into tins. The second example is his last published paper which was in social sciences. There he applied statistical thermodynamics, using the method of “the most probable distribution” as discussed by Schrödinger, to model the distribution of income within a population based on the interaction between individuals. The model could be reasonably well fit to Swedish income distribution. He commented that “The stability of the distributions is a result of the random interaction between individuals of the population in its strife for food, shelter and safety”.
Eriksson, E. (2003) På äventyr i Arktis 1956, Geologiskt forum, Geologiska Föreningen, Stockholm, Nr 38, juni 2003, årgång 10. (In Swedish. English title ”Adventure in the Arctic 1956”.)
Taba, H. (1998) The Bulletin Interviews Erik Eriksson, WMO Bulletin, Volume 47, No. 4, October 1998.
Uppsala University Archives, Kansliarkivet, D XV:15
Eriksson, E. (1952) Composition of atmospheric precipitation. I. Nitrogen compounds. Tellus 4, 215-232.
Eriksson, E. (1952) Composition of atmospheric precipitation. II. Sulfur, chloride, iodine compounds. Bibliography. Tellus 4, 280-303.
Eriksson, E. (1955) Air borne salts and the chemical composition of river waters. Tellus 7, 243-250.
Eriksson, E. (1958) The possible use if tritium for estimating groundwater storage. Tellus 10, 472-478.
Eriksson, E. (1959) The circulation of some atmospheric constituents in the sea. In Bolin, B. (Ed) “The Rossby Memorial Volume”, Rockefeller Inst. Press, New York, 147-157.
Eriksson, E. (1959) The yearly circulation of chloride and sulfur in nature: meteorological, geochemical and pedological implications. Part I. Tellus 11(4), 375-403.
Bolin, B. & Eriksson, E. (1959) Changes in the carbon dioxide content of the atmosphere and sea due to fossil fuel combustion. In: Bolin, B. (Ed.) “The atmosphere and the sea in motion: The Rossby memorial volume”, Rockefeller Institute Press, New York, 30-142.
Eriksson, E. (1960) The yearly circulation of chloride and sulfur in nature; Meteorological, geochemical and pedological implications. Part II. Tellus, 12(1), 64-109.
Eriksson, E. (1961) Natural reservoirs and their characteristics. Geofisica International 1, 27-43.
Eriksson, E. (1963) The yearly circulation of sulfur in nature. J. Geoph. Research 68, 4001-4008.
Eriksson, E. (1963) Atmospheric tritium as a tool for the study of certain hydro logic aspects of river basins. Tellus 15, 303-308.
Eriksson, E. (1965) An account of the major pulses of tritium and their effects on the atmosphere. Tellus l7, 118-130.
Eriksson, E. (1965) Deuterium and oxygen-18 in precipitation and other natural waters. Tellus 17, 498-512.
Eriksson, E. (1967) Large-scale utilization of tritium in hydrologic studies. Geoph. Monograph No 11, 153-156.
Eriksson, E. (1971) Compartment models and reservoir theory. Annual Reviews of Ecology and Systematics. Vol. 2, 67-84.
Eriksson, E. (1985) Principles and applications of hydrochemistry. Chapman & Hall, London, New York, 187 pp.