Phosphorus Concentrations and Loads in Surface Waters in Central Illinois. (6363)
Authors:
L.E. Gentry* - Univ. of Illinois M.B. David - Univ. of Illinois K.M. Starks - Univ. of Illinois C.A. Mitchell - Univ. of Illinois
Abstract:
Phosphorus (P) is considered to be the primary growth limiting factor of algae and other aquatic plants in freshwater systems. In this study we compare P concentrations and annual loadings in the upper reaches of three extensively tile-drained agricultural watersheds in central Illinois (Embarras, Kaskaskia, and Sangamon Rivers). Our longest data set has been collected on the Embarras River at Camargo IL, and during the past ten years the annual flow-weighted mean dissolved reactive P (DRP) concentration has ranged from 0.13 to 0.21 mg/L. In general, DRP concentrations in surface waters of central Illinois were high (greater than 0.20 mg/L) during storm runoff events, and low (less than 0.03 mg/L) during baseline flow in the summer and fall; however, total P concentrations tend to increase at this time due to algal growth. For all three watersheds, the highest DRP concentrations occurred on January 30, 2001 during a modest discharge event following a period of snowmelt and 2.3 cm of rainfall. These conditions created a worse case scenario for P movement and river samples contained 0.63, 0.73, 1.25 mg/L of DRP for the Embarras, Kaskaskia, and Sangamon Rivers, respectively. These data, as well as data collected throughout Illinois during the next year, will be used by ILEPA to establish an ambient P nutrient standard to facilitate the Total Maximum Daily Load process.
Speaker Information: Lowell Gentry, Univ. of Illinois, 1102 S. Goodwin Ave., Urbana, IL 61801; Phone:
217-333-1769; E-mail: [email protected]
Session Information: Tuesday, November 2, 2004, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 0601) Keywords: phosphorus; agricultural; tile drained; watersheds
