Influence of Clay Mineralogy On Soil Dispersion Behavior and Water Quality.

Currently, there is very little research available on nonpoint source pollution from rural watersheds. Government regulatory agencies are desperate for what little information they can gather on the causes of nonpoint source pollution which includes soil indicators such as clay dispersivity and the relationship between clay dispersivity and resulting suspended loads in surface waters. Since soil dispersion is dependent on clay mineralogy, knowing the clay mineralogy of an area can help predict sediment loads entering the surrounding surface waters. This information is necessary to protect the resource value of our rivers, lakes, and estuaries, as well as to protect recreational activities such as fishing or hunting; but most importantly, this information is necessary to ensure the safety of our drinking water supply. Clay mineralogy and its influence on dispersion, as well as dispersion and its relation to water quality are the focus of this study. Soil mineralogy affects water quality in several ways: Soil mineralogy determines the dispersivity of the clay portion of the soil and dispersive clays are likely to end up as suspended sediment in surface waters, weathering reactions contribute elements to water as dissolved load, and clay minerals, with their sorption properties, contribute to soils' ability to filter and carry pollutants. Through the use of X-ray diffraction, dispersivity, atomic absorption spectrometry, cation exchange capacity, and petrographic microscopy this study will show that the clay mineral fraction of a soil determines the dispersivity, and that dispersed clay minerals contribute excess nutrients and metals as nonpoint source pollutants to surface waters.