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A discussion is presented which shows the types of information that may be gleaned from the chemical, mineralogical, and biological analyses of lake muds. Illustrations are taken from a variety of studies carried out in various countries.
Substantial rises in the concentration of sulfur in the recently deposited mud as well as in the surface water of Linsley Pond (North Branford, Connecticut) are indicative of industrial expansion in the region over the past five decades. Similarly, stack emissions produced by the combustion of fossil fuels have caused rises in sulfur concentrations and subsequent changes in pH in unbuffered waters of Southern and Southwestern Scandinavia. These phenonmena have brought about shifts in population size and distribution among the lake plankton.
Recent technological growth has resulted in a progressive increase in mercury in the sediments of Lake Windermere, United Kingdom, Lake Huleh, Israel, and Lake Biwa, Japan. No doubt reflecting man's global activities, similar rises in concentrations of lead, cadmium, and silver have been noted in recently deposited muds in various sections of the world. The steady rise of phthalates noted in recently deposited sediments is indicative of the advent of the use of plastics in the many areas of human endeavor.
To ascertain which of the various hypotheses advanced to explain the sudden collapse of the ancient Mayan culture in Central America were valid, a series of lake cores were taken in Guatemala and subjected to chemical and biological analyses. The ecologically oriented hypothesis appears to be invalid. Furthermore, these studies showed that a high agricultural civilization developed and that under modern conditions a larger agricultural population employing indigenous methods can be supported. In addition, these investigations showed that early man changed a savanna to a tropical forest and that his activities brought about only a small increase in the erosion rate.
Additionally, paleoecological methods may be used to elucidate past climates, the advent of agriculture in a region, processes of plant selection and domestication, effects of slash and burn agriculture, the size of one time plankton populations, the chemical concentration of the atmosphere in ancient times, the history of a landscape, and the effect of road building on nearby lakes.
uses of the past, sulfur, mercury, cadmium, silver, ancient Maya, seasonal swamps, Laguna de Petenxil, phthalates, ice cores, slash and burn agriculture
Associate environmental consultant, Health and Environmental Sciences, Mammalian and Environmental ToxicologyThe Dow Chemical Co., Midland, MI