Abraham Lerman Professor Ph.D., Harvard University, 1964 847-491-7385 abe@earth.northwestern.edu

Research Interests
Global biogeochemical cycles in the geologic past and present; geochemical and transport processes in the surficial and underground environment; natural and anthropogenic controls of geochemical systems.

Research Projects

Biogeochemical Cycles and Global Change [A. Lerman, F. T. Mackenzie (Honolulu)]
We are studying the global biogeochemical cycles of such life-important elements as carbon, phosphorus and nitrogen, and developing conceptual and mathematical models of these cycles that are compatible with the available data and our understanding of the C-N-P-O system in the geological past. A continuing effort in this direction is a study of the geochemical cycles and pathways of biologically important heavy metals tied to the cycles of the biota-building C and P. This involves studying the major geomaterial fluxes on the continents and from the continents to the oceans. Work on the basic geochemical mechanisms controlling the fluxes on the Earth's surface includes theoretical and modelling studies of the feedback mechanisms in lakes, solid-solution reactions in suspended materials, and acidification or alkalinization of continental waters in relation to the global CO ₂ increase in the atmophere. Human activity that creates wastes often competes with the magnitudes of sedimentary and geochemical processes on environmentally large scales. Human-made perturbations of the geochemical processes and their long-term consequences are being studied within the major biogeochemical cycles and within specific environments. The broader goals of this research are to understand the responses and geologically preservable records of global change in the past, present, and future.

Transport of contaminants in salt deposits [A. Lerman, P. A. Domenico (College Station, Texas)
Salt beds and other structures underground are being used as repositories or disposal sites for a variety of wastes and industrially needed materials (e.g., petroleum and gas). Nuclear and other solidified wastes, placed in large-scale cavities or excavated caverns in salt structures pose dangers of gas generation and waste dissolution, with potential migration and entry of hazardous chemicals in the biosphere. In the generic case of solidified wastes that come in contact with halite-saturated brines in a salt formation underground, we identified the main mechanisms of potential release of contaminants by dissolution and gas generation. We also developed models for the rates of travel of dissolved and gaseous contaminants in a radially isotropic medium, and demonstrated the conditions under which they would not reach the biosphere on time scales of thousands to tens of thousands of years.

Development and Consumption of Acidity in Natural Waters [A. Lerman, B. Fritz (Strasbourg)]
We are looking at detailed records of acidity in two streams, draining geologically different terrains in the Vosges Mountains, in order to asses the mechanisms and rates of neutralization of acidity in surface and shallow subsurface waters. The goal of this work, started recently, is to separate anthropogenic from natural acidity sources, and to identify the mechanisms of acidity neutralization by water-rock reactions.

Ar/K ratios as indicators of diagenesis in sedimentary sequences [A. Lerman, N. Clauer (Strasbourg), S. Chaudhuri (Manhattan), D. Eberle (Denver)]

Bibliography 1990 to present

Lerman, A., Transport and kinetics in surficial processes, in W. Stumm (ed.), Aquatic Chemical Kinetics , pp. 505-534, Wiley, New York, 1990.

Lerman, A., Biogeochemical cycles, in S. F. Singer (ed.), The Ocean in Human Affairs, pp. 23-42, Paragon House, New York, 1990.

Lerman, A., Weathering and erosional controls of geochemical cycles, Chem. Geol., 84, 13-14, 1990.

Mackenzie, F. T., L. M. Ver, C. Sabine, M. Lane, and A. Lerman, C,N,P,S global biogeochemical cycles and modeling of global change, NATO ASI Series I, 4, pp. 1-62, Springer-Verlag, New York 1993.

Lerman, A., F. T. Mackenzie and L. M. Ver, Global nitrogen cycle within the couples C-N-P system, Chem. Geol., 107, 389-392, 1993.

Lerman, A., and P. A. Domenico, Dissolved and gaseous contaminant transport in salt deposits, Chem. Geol., 107, 427-430, 1993.

Lerman, A., Surficial weathering fluxes and their geochemical controls, in Material Fluxes on the Surface of the Earth, pp. 28-45, 1994.

Ver, L.M.B., Mackenzie, F.T., and Lerman, A., Modeling pre-industrial C-N-P-S biogeochemical cycling in the land-coastal margin system, Chemosphere, 29, pp. 855-887, 1994.

Books

Lerman, A. (ed.), Lakes: Chemistry, Geology, Physics , Springer-Verlag, New York, 385 pp., 1978.

Lerman, A., Geochemical Processes-Water and Sediment Environments, Wiley-Interscience, New York, 480 pp., 1979. Reprint edition, Krieger Publishing Company, Malabar, Fla., 481 pp., 1988.

Lerman, A. and M. Meybeck (eds.), Physical and Chemical Weathering in Geochemical Cycles, Kluwer Academic Publishers (NATO ASI Ser. C-251), Dordrecht and Boston, 375 pp., 1988.

Lerman, A., Gat, J.R., and Imboden, D.M. (ed.), Lakes , Springer-Verlag, Heidelberg, in press 1995.