The Mississippi River Basin Nitrogen Problem: Past History and Future Challenges to Solve It

Ritter, William F.; Chitikela, S. Rao

doi:10.1061/9780784483060.010

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…The open Gulf of Mexico is subtropical, permanently stratified and oligotrophic (Yuan et al., 2004). Consequently, discharge from the Mississippi River to the northern coast promotes phytoplankton growth (Ritter & Chitikela, 2020) on a scale which can be detected easily using the methodology used in this paper. This is crucial information because discharges from Mississippi and Atchafalaya rivers have repeatedly resulted in far‐reaching algae blooms which deplete oxygen from the water column with the devastating consequence of mass fish kills.…”

Section: Resultsmentioning

confidence: 99%

“…In 2019, after several years under the implementation of a Hypoxia Task Force by the US Environmental Protection Authority, the Gulf of Mexico hypoxic zone covered an area of ~18 005 km 2 . This was the eighth largest extent recorded since 1985 and was far larger than the goal of 5000 km 2 set by the task force (Ritter & Chitikela, 2020). Usually, the coverage of the anoxic area is estimated by conducting cruises off the coast, and taking in situ measurements (Fennel & Laurent, 2018;Lohrenz et al, 2008;Walker, 1996).…”

Section: Patterns Of Influence In Tropical and Subtropical Regionsmentioning

confidence: 99%

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Mapping the long‐term influence of river discharge on coastal ocean chlorophyll‐a

Auricht

Mosley

Lewis

et al. 2022

Remote Sens Ecol Conserv

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Although the potential of river discharge to support ocean productivity and marine ecosystems is known, the specifics of this relationship are poorly understood in many regions of the world. Global estimates of river flow indicate that river discharge is decreasing due to the increasing fragmentation, extraction and regulation of rivers. This likely means that the contribution of river flow to coastal productivity and water quality is changing, potentially leading to fewer and smaller magnitude ocean fertilisation events. We developed a simple analysis method, based on Earth observation data, to investigate where coastal ocean chlorophyll-a is most strongly influenced by river discharge. The per-pixel spatiotemporal correlation technique (implemented using Python) correlates chlorophyll-a concentration (a proxy for phytoplankton biomass and indicator of primary productivity) from MODIS ocean colour data with river discharge data. The method was tested globally on 11 different rivers discharging into coastal ocean regions. Our findings suggest some of the world's largest river systems, such as the Amazon River, have zones of elevated coastal chl-a that extend hundreds to thousands of km from the river mouth. These findings suggest the influence of river discharge may have been underestimated in many coastal regions of the world. The method appears more effective for larger river systems discharging to ocean waters with less complex nutrient dynamics and weaker seasonal productivity patterns, most notably in temperate regions. Increasing our understanding of the specific areas influenced by river discharge, and the degree of influence over space and time, is an important step towards the improved river and coastal management. This method will increase the capacity of researchers to monitor how, when and where coastal waters are affected as river discharge continues to change into the future.

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Section: Resultsmentioning

confidence: 99%

Section: Patterns Of Influence In Tropical and Subtropical Regionsmentioning

confidence: 99%

Mapping the long‐term influence of river discharge on coastal ocean chlorophyll‐a

Auricht

Mosley

Lewis

et al. 2022

Remote Sens Ecol Conserv

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“…Excessive nutrient loads can contribute to eutrophication, leading to adverse effects on aquatic ecosystems and water quality (Carpenter et al, 1998). For instance, excessive nutrient loading from cropland in the Mississippi River Basin is a significant contributing factor to the formation of the hypoxic zone in the northern Gulf of Mexico (Ritter and Chitikela, 2020). Assessing the immediate and long-term 55 impact of hurricanes on water quality in the affected ecosystems is challenging due to logistical constraints associated with sampling during these events (Filippino et al, 2017).…”

Section: Introduction 30mentioning

confidence: 99%

Short-term effects of hurricanes on nitrate-nitrogen runoff loading: a case study of Hurricane Ida using E3SM land model (v2.1)

Fang,

Tran,

Leung

2024

Preprint

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Abstract. When nutrient level in the soil surpasses vegetation demand, nutrient losses due to surface runoff and subsurface leaching are the major reasons for the deterioration of water quality. The Lower Mississippi river basin (LMRB) is one of the sub-basins that deliver the highest nitrogen loads to the Gulf of Mexico. Potential changes in episodic events induced by hurricanes may exacerbate water quality issue in the future. However, uncertainties in modeling the hydrologic response to hurricanes may limit the modeling of nutrient losses during such events. Using a machine learning approach, we calibrated the land component of the Energy Exascale Earth System model (E3SM), or ELM, version 2.1, based on the water table depth (WTD) of a calibrated 3D subsurface hydrology model. While the overall performance of the calibrated ELM is satisfactory, some discrepancies in WTD remain in slope areas with low precipitation due to the missing lateral flow process in ELM. Simulations including biogeochemistry performed using ELM with and without model calibration showed important influences of soil hydrology, precipitation intensity, and runoff parameterization on the magnitude of nitrogen runoff loss and leaching pathway. Despite such sensitivities, both ELM simulations produced reduced WTD and increased runoff and accelerated nitrate-nitrogen runoff loading during Hurricane Ida in August 2021, consistent with the observations. With observations suggesting more pronounced effects of Hurricane Ida on nitrogen runoff than the simulations, we identified factors for model improvement to provide a useful tool for studying hurricane-induced nutrient losses in the LMRB region.

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Sustainable Agriculture Water Management

Ritter¹

2023

Encyclopedia of Sustainability Science and Technology Series

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The Mississippi River Basin Nitrogen Problem: Past History and Future Challenges to Solve It

Cited by 6 publications

References 11 publications

Mapping the long‐term influence of river discharge on coastal ocean chlorophyll‐a

Mapping the long‐term influence of river discharge on coastal ocean chlorophyll‐a

Short-term effects of hurricanes on nitrate-nitrogen runoff loading: a case study of Hurricane Ida using E3SM land model (v2.1)

Sustainable Agriculture Water Management

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