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

DISSOLVED PHOSPHATE CONCENTRATIONS IN IOWA SHALLOW GROUNDWATER

Paper number: 26-2
Program: Theme Sessions
Time: 8:05 AM – 8:25 AM

Authors

Abstract

Regional groundwater phosphorus (P) concentrations are rarely reported and it is important to develop a better understanding of background concentrations in shallow groundwater to help develop strategies to mitigate environmental risks. In this study, results collected from 17 different Iowa-based studies conducted from 2006 to 2019 and a total of 210 discrete locations of water table dissolved phosphate (DPO43-) measurements were summarized to:1) assess the occurrence, range and statistical distribution of groundwater DPO43- concentrations in Iowa; and 2) evaluate state-wide patterns of DPO43-concentrations related to land use/land cover and landscape position. DPO43- concentrations ranged from 0.02 to 1.56 mg L-1, averaged 0.15±0.19 mg L-1 with a median value of 0.10 mg L-1 (95% CI of 0.08 to 0.11 mg L-1). Variations were observed among land cover class and landscape position, but concentrations exhibited remarkable uniformity across the state, likely attesting to the legacy of P from historical agricultural management. Median concentrations are higher than typical water quality criteria used to assess risk to surface water systems, implying that simply discharging groundwater DPO43-- to streams, rivers and lakes would be sufficient to cause environmental degradation.

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

doi: 10.1130/abs/2020NC-347858

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