26 Groundwater Quality Degradation and Protection: Water Quality Assessment, Modeling and Uncertainty Analysis, and Water Supply Management

Tuesday, 19 May 2020
8:00 AM - 12:00 PM
Lake Superior Ballroom MN

EVALUATING THE ADVECTIVE CAPACITY OF REGIONAL FLOW REGIMES TO TRANSPORT LEGACY PHOSPHORUS ON A TILED FARM FIELD, NORTHWEST OHIO

Paper number: 26-3
Program: Theme Sessions
Time: 8:25 AM – 8:45 AM

Authors

Abstract

Harmful and nuisance algal blooms resulting from excess phosphorus loads is an issue of increasing importance for the water quality of the western Lake Erie basin. Dissolved reactive phosphorus (DRP) is delivered to Lake Erie from the Maumee River watershed which is dominated by agricultural land use. After decades of farmers adopting conservation land and crop management practices in the Maumee watershed, many fields still test above recommended soil phosphorus levels due to the presence of legacy phosphorus in the near surface soil profile. Legacy phosphorus non-point sources are currently exacerbating DRP loading in the Maumee watershed.

A demonstration farm field located in the lower Maumee watershed was selected as a study area to evaluate the contributions of regional groundwater flow regimes and flow paths to the advective transport of legacy phosphorus. A network of piezometers was installed throughout the farm field to monitor the regional potentiometric surface and to allow for groundwater sampling. A modified current flow meter and datalogger were placed in the tile effluent outlet to record discharge velocities and volumes. Preliminary results indicate elevated concentrations of DRP present in piezometers (0.142mg/L) and in tile drain effluent (0.200mg/L) during the late spring months of 2019. A positive correlation between elevated DRP concentrations in discharge effluent, DRP concentration gradients in piezometers, and discharge hydrograph frequency indicate groundwater transport of legacy DRP. These preliminary data sets highlight the importance groundwater flow regimes play in transporting legacy phosphorus within an artificially drained unconfined aquifer characteristic of the lower Maumee watershed.

Geological Society of America Abstracts with Programs. Vol. 52, No. 5

doi: 10.1130/abs/2020NC-347478

© Copyright 2020 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.