Dominant Processes that Affect Nutrient Retention in Small Streams of the Missouri Ozarks
Cem Selman, Dev K. Niyogi, and Mark W. Fitch. Civil, Architectural & Environmental Engineering, University of Missouri-Rolla, Butler Carlton Civil Engineering Hall, Rolla, MO 65409-0030
Nutrients, mostly produced from human activities, are carried through streams to open-water systems (lakes, estuaries, and coastal areas) that are sensitive to nutrient pollution. As nutrients are transported in streams, they may be taken up by stream microorganisms, adsorbed, or transformed into other compounds. However, the exact mechanisms of nutrient retention in streams are still not well understood. The object of this research is to quantify the major mechanisms that affect nutrient retention and uptake in several small streams in the Missouri Ozarks. Experimental systems were used to measure the effects of single parameters, such as discharge, nutrient concentration, light intensity, and algal abundance and type, on uptake rates of phosphorus. Uptake rates were highest under intermediate discharge. Uptake rates under varying phosphorus concentrations followed Michaelis-Menten kinetics, but with a very high half-saturation concentration. Surprisingly, light did not have a significant effect on uptake rates. After determination of dominant processes, an engineering solution that will enhance nutrient removal in lotic systems will be developed.