11 Geomorphology, Hydrology, and Critical Zone Processes in the Anthropocene (Posters)

Monday, 18 April 2016
8:00 AM - 12:00 PM
Illinois Ballroom AB

LOAD CALCULATION OF NUTRIENTS IN CEDAR RIVER WATERSHED IN SUPPORT OF IOWA’S NUTRIENT REDUCTION STRATEGY

Paper number: 11-1
Program: Theme Sessions
Time: 8:00 AM – 12:00 PM

Authors

  • M. Iqbal Presenting Author
    University of Northern Iowa, Cedar Falls, IA
  • S. Tuladhar
    University of Northern Iowa, Cedar Falls, IA
  • A. Petrov
    University of Northern Iowa, Cedar Falls, IA
  • A. Worthy
    University of Northern Iowa, Cedar Falls, IA

Abstract

Surface water from eighteen (18) sites within the Cedar River watershed in Iowa were sampled for total suspended sediments (TSS), dissolved nitrogen (N) and total phosphorus (TP) from April through October of 2014. The selected sites are located from Charles City all the way to LaPorte City, Iowa. The Cedar River has a total drainage area of 7,815 mi2, where 81% of all land use is agriculture. Iowa farm fields are known sources of nutrients that are responsible for developing hypoxia in the Gulf of Mexico. In recent years, the 12 states along the Mississippi River have taken important initiatives against loss of nutrients from their agricultural fields.

Nitrogen loads were high from early to mid-summer due to the rapid conversion of fertilizer nitrogen into nitrate before the crops entered the period of maximum uptake. The levels went up again toward the later part of fall being derived from the residual organic nitrogen converting into nitrate through the process of nitrification. This was also because nitrogen uptake by crops was considerably reduced by mid to late August. The average nitrogen (as nitrate-N) loads in the watershed ranged from 8.4 tons/day in site 17 (Wolf Creek) to 156.6 tons/day in site 13 (Cedar River at Waterloo). The average load over all sites was 45 tons/day. The total loss of nitrogen for the season was calculated as 9450 tons. Loads of TP directly correlate with the transport of TSS in the watershed. Phosphorus is heavily adsorbed to soil particles and is transported to the streams with eroded soils. The TP loads ranged from 0.12 tons/day in site 17 (Wolf Creek) to 3.12 tons/day in site 12 (Cedar River at Cedar Falls). The average load over all sites was 1.05 tons/day. The total loss of phosphorus for the season was calculated as 221 tons. Taking Cedar River as an example, it is clear that rivers in eastern Iowa contribute high amounts of nutrients to the formation of hypoxia in the Gulf of Mexico.

Geological Society of America Abstracts with Programs. Vol. 48, No. 5

doi: 10.1130/abs/2016NC-274913

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.