Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Water Res. 2002 Feb;36(3):788-92.

Nitrate flux from aquifer storage in excess of baseflow contribution during a rain event.

Author information

  • Department of Earth Science, University of Northern Iowa, Cedar Falls 50614, USA. m.iqbal@uni.edu

Abstract

Nitrate flux from a bedrock aquifer due to a storm was calculated by hydrograph separation. The hydrograph generated by a 20-mm rain in Cedar River of Iowa was separated into the following three components: the constant baseflow, the rainwater, and the water released from aquifer in excess of baseflow. The separation was conducted by using oxygen isotopes, dissolved nitrate, and stream discharge. The peak discharge was 33h long. During this period, the water released from the aquifer storage in excess of baseflow was 36% of the total discharge. The rainwater and the pre-storm baseflow equivalents were 17% and 47%, respectively. The nitrate concentrations in the instantaneous discharge ranged between 8.6 and 10.0 mg/L. The average concentrations in the rainwater and the baseflow were 3.7 and 9.8 mg/L, respectively. A total of 3.6 x 10(5) mol of nitrate was transported by the stream during the 33 h of peak discharge. Approximately 35% (1.3 x 10(5) mol) of this mass was derived from the aquifer storage in excess of baseflow contribution. The rainwater and the constant baseflow equivalentswere 7% (2.6 x 10(4) mol) and 58% (2.1 x 10(5) mol), respectively. The release of a significant amount of nitrate from the aquifer suggests that the local geology is favorable for vertical recharge of rainwater which causes an increased fluid pressure within the aquifer forcing ground water to discharge laterally into the stream. Such observation also implies that the aquifer is effectively flushed out during storms, thus restricting long term build-up of nitrate from agricultural sources.

PMID:
11827340
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk