Baseflow nitrate dynamics within nested watersheds of an agricultural stream in Nebraska, USA

Galen Richards; Troy E. Gilmore; Aaron R. Mittelstet; Tiffany L. Messer; Daniel D. Snow

doi:10.1016/j.agee.2020.107223

Baseflow nitrate dynamics within nested watersheds of an agricultural stream in Nebraska, USA

Galen Richards, Troy E. Gilmore, Aaron R. Mittelstet, Tiffany L. Messer, Daniel D. Snow

Research output: Contribution to journal › Article › peer-review

15 Scopus citations

Abstract

There is a need to evaluate high surface nitrate concentrations across agricultural watersheds, both spatially and temporally, to increase understanding of source and timing of nitrogen loads in streams and rivers. Bazile Creek is a high-nitrate stream originating in the agriculturally intensive Bazile Groundwater Management Area of Eastern Nebraska, USA. It is a gaining stream that receives groundwater with high nitrate concentrations originating from nonpoint sources. The objective of this study was to determine spatial and temporal variability of baseflow nitrate concentrations in Bazile Creek and its tributaries and to relate this variability to watershed characteristics. Surface-water nitrate samples were collected monthly from July 2018 through September 2019 from nine sites in the watershed and were analyzed for nitrate concentration. Average surface water nitrate-N concentrations within the watershed ranged from 2.7 to 15 mg L⁻¹ and were significantly different between the sites (p < 0.05). Surface water nitrate-N concentrations varied seasonally in the main channel, recording the highest concentrations in winter (December-February, average = 14.4 mg L⁻¹) when the discharge was minimum. High nitrate-N concentrations were observed in two of the five sampled tributaries, suggesting steady inputs of high-nitrate groundwater. The results of this study reveal substantial spatial variation in surface-water nitrate concentrations in the headwaters despite the close proximity of sampling sites. This study demonstrates that sampling tributaries along with the main channel of a stream is beneficial in determining nitrate inputs, variability and overall contaminant loading to a watershed.

Original language	English
Article number	107223
Journal	Agriculture, Ecosystems and Environment
Volume	308
DOIs	https://doi.org/10.1016/j.agee.2020.107223
State	Published - Mar 1 2021

Bibliographical note

Funding Information:
Funding for this research was provided by Nebraska Department of Environment and Energy Project # 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project 1015698 . The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance.

Funding Information:
Funding for this research was provided by Nebraska Department of Environment and Energy Project# 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project1015698. The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance.

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

Baseflow nitrate-N
Groundwater
Non-point source pollution
Seasonality

ASJC Scopus subject areas

Ecology
Animal Science and Zoology
Agronomy and Crop Science

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10.1016/j.agee.2020.107223

Cite this

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title = "Baseflow nitrate dynamics within nested watersheds of an agricultural stream in Nebraska, USA",

abstract = "There is a need to evaluate high surface nitrate concentrations across agricultural watersheds, both spatially and temporally, to increase understanding of source and timing of nitrogen loads in streams and rivers. Bazile Creek is a high-nitrate stream originating in the agriculturally intensive Bazile Groundwater Management Area of Eastern Nebraska, USA. It is a gaining stream that receives groundwater with high nitrate concentrations originating from nonpoint sources. The objective of this study was to determine spatial and temporal variability of baseflow nitrate concentrations in Bazile Creek and its tributaries and to relate this variability to watershed characteristics. Surface-water nitrate samples were collected monthly from July 2018 through September 2019 from nine sites in the watershed and were analyzed for nitrate concentration. Average surface water nitrate-N concentrations within the watershed ranged from 2.7 to 15 mg L−1 and were significantly different between the sites (p < 0.05). Surface water nitrate-N concentrations varied seasonally in the main channel, recording the highest concentrations in winter (December-February, average = 14.4 mg L−1) when the discharge was minimum. High nitrate-N concentrations were observed in two of the five sampled tributaries, suggesting steady inputs of high-nitrate groundwater. The results of this study reveal substantial spatial variation in surface-water nitrate concentrations in the headwaters despite the close proximity of sampling sites. This study demonstrates that sampling tributaries along with the main channel of a stream is beneficial in determining nitrate inputs, variability and overall contaminant loading to a watershed.",

keywords = "Baseflow nitrate-N, Groundwater, Non-point source pollution, Seasonality",

author = "Galen Richards and Gilmore, {Troy E.} and Mittelstet, {Aaron R.} and Messer, {Tiffany L.} and Snow, {Daniel D.}",

note = "Funding Information: Funding for this research was provided by Nebraska Department of Environment and Energy Project # 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project 1015698 . The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance. Funding Information: Funding for this research was provided by Nebraska Department of Environment and Energy Project# 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project1015698. The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance. Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",

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AU - Gilmore, Troy E.

AU - Mittelstet, Aaron R.

AU - Messer, Tiffany L.

AU - Snow, Daniel D.

N1 - Funding Information: Funding for this research was provided by Nebraska Department of Environment and Energy Project # 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project 1015698 . The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance. Funding Information: Funding for this research was provided by Nebraska Department of Environment and Energy Project# 56-1641 as well as U.S. Department of Agriculture National Institute of Food and Agriculture Hatch Project1015698. The authors appreciate the time and effort that the anonymous reviewers have taken to improve this manuscript. We would like to thank Alan Boldt, Sydney Corcoran, Caner Zeyrek, Mikaela Cherry, and Mason Johnson for assisting with fieldwork, the Lewis and Clark, Lower Elkhorn, Lower Niobrara, and Upper Elkhorn Natural Resources Districts for their support, and the landowners who allowed us access to their property for the purposes of collecting samples and installing equipment; this research would not have been possible without their assistance. Publisher Copyright: © 2020 Elsevier B.V.

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N2 - There is a need to evaluate high surface nitrate concentrations across agricultural watersheds, both spatially and temporally, to increase understanding of source and timing of nitrogen loads in streams and rivers. Bazile Creek is a high-nitrate stream originating in the agriculturally intensive Bazile Groundwater Management Area of Eastern Nebraska, USA. It is a gaining stream that receives groundwater with high nitrate concentrations originating from nonpoint sources. The objective of this study was to determine spatial and temporal variability of baseflow nitrate concentrations in Bazile Creek and its tributaries and to relate this variability to watershed characteristics. Surface-water nitrate samples were collected monthly from July 2018 through September 2019 from nine sites in the watershed and were analyzed for nitrate concentration. Average surface water nitrate-N concentrations within the watershed ranged from 2.7 to 15 mg L−1 and were significantly different between the sites (p < 0.05). Surface water nitrate-N concentrations varied seasonally in the main channel, recording the highest concentrations in winter (December-February, average = 14.4 mg L−1) when the discharge was minimum. High nitrate-N concentrations were observed in two of the five sampled tributaries, suggesting steady inputs of high-nitrate groundwater. The results of this study reveal substantial spatial variation in surface-water nitrate concentrations in the headwaters despite the close proximity of sampling sites. This study demonstrates that sampling tributaries along with the main channel of a stream is beneficial in determining nitrate inputs, variability and overall contaminant loading to a watershed.

AB - There is a need to evaluate high surface nitrate concentrations across agricultural watersheds, both spatially and temporally, to increase understanding of source and timing of nitrogen loads in streams and rivers. Bazile Creek is a high-nitrate stream originating in the agriculturally intensive Bazile Groundwater Management Area of Eastern Nebraska, USA. It is a gaining stream that receives groundwater with high nitrate concentrations originating from nonpoint sources. The objective of this study was to determine spatial and temporal variability of baseflow nitrate concentrations in Bazile Creek and its tributaries and to relate this variability to watershed characteristics. Surface-water nitrate samples were collected monthly from July 2018 through September 2019 from nine sites in the watershed and were analyzed for nitrate concentration. Average surface water nitrate-N concentrations within the watershed ranged from 2.7 to 15 mg L−1 and were significantly different between the sites (p < 0.05). Surface water nitrate-N concentrations varied seasonally in the main channel, recording the highest concentrations in winter (December-February, average = 14.4 mg L−1) when the discharge was minimum. High nitrate-N concentrations were observed in two of the five sampled tributaries, suggesting steady inputs of high-nitrate groundwater. The results of this study reveal substantial spatial variation in surface-water nitrate concentrations in the headwaters despite the close proximity of sampling sites. This study demonstrates that sampling tributaries along with the main channel of a stream is beneficial in determining nitrate inputs, variability and overall contaminant loading to a watershed.

KW - Baseflow nitrate-N

KW - Groundwater

KW - Non-point source pollution

KW - Seasonality

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Baseflow nitrate dynamics within nested watersheds of an agricultural stream in Nebraska, USA

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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