Effects of adsorbed natural organic matter on the erosion of kaolinite sediments

Author： Dennett Keith E. Sturm Terry W. Amirtharajah Appiah Mahmood Talat

ISSN： 1061-4303

Source： Water Environment Research, Vol.70, Iss.3, 1998-05, pp. : 268-275

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Abstract

The erosion of kaolinite sediments with various concentrations of adsorbed natural aquatic organic matter was studied. Experiments were conducted in a recirculating flume under uniform flow conditions. The erosion rates were generally lower at the lowest and highest concentrations of adsorbed natural organic matter (NOM) tested. The erosion rates for the intermediate concentrations of adsorbed NOM were slightly higher. As the concentration of adsorbed NOM increased, the water content of the sediment decreased dramatically. This was probably the result of the reorientation of the sediment particles from mostly edge-to-face associations at lower NOM concentrations to mostly face-to-face associations at higher NOM concentrations. The erosion rates increased linearly as bed shear stress increased for all concentrations of adsorbed NOM. The critical shear stress generally decreased as the concentration of adsorbed NOM increased. This result is significant because sediments with higher concentrations of organic matter may be more reactive with environmental contaminants and may also be more susceptible to erosion.