Direct groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States

Knights, Deon; Parks, K.; Sawyer, Audrey H.; David, Cédric H.; Browning, Trevor N.; Danner, Kelsey M.; Wallace, Corey D.

doi:10.1016/j.jhydrol.2017.09.001

Cited by 21 publications

(7 citation statements)

References 73 publications

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“…Most agricultural areas are in the southern portion of the basin (Figure S2) and produce substantial nutrient loads to the lakes . Because of humid continental climates and broad areas with very permeable soils and high aquifer recharge, 43% of the US-GLB coast is vulnerable to groundwater-borne nutrients. , Harmful algal blooms in the GLB have been a critical issue for millions who live in the region, resulting in negative effects on industries (e.g., fishery, tourism, aquaculture), ecology (e.g., fish kills), and public health (e.g., drinking water contamination, toxicity to pets and livestock). − …”

Section: Study Area and Model Inputsmentioning

confidence: 99%

Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport

Wan,

Kendall,

Martin

et al. 2023

Environ. Sci. Technol.

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Nitrogen and phosphorus pollution is of great concern to aquatic life and human well-being. While most of these nutrients are applied to the landscape, little is known about the complex interplay among nutrient applications, transport attenuation processes, and coastal loads. Here, we enhance and apply the Spatially Explicit Nutrient Source Estimate and Flux model (SENSEflux) to simulate the total annual nitrogen and phosphorus loads from the US Great Lakes Basin to the coastline, identify nutrient delivery hotspots, and estimate the relative contributions of different sources and pathways at a high resolution (120 m). In addition to in-stream uptake, the main novelty of this model is that SENSEflux explicitly describes nutrient attenuation through four distinct pathways that are seldom described jointly in other models: runoff from tile-drained agricultural fields, overland runoff, groundwater flow, and septic plumes within groundwater. Our analysis shows that agricultural sources are dominant for both total nitrogen (TN) (58%) and total phosphorus (TP) (46%) deliveries to the Great Lakes. In addition, this study reveals that the surface pathways (sum of overland flow and tile field drainage) dominate nutrient delivery, transporting 66% of the TN and 76% of the TP loads to the US Great Lakes coastline. Importantly, this study provides the first basin-wide estimates of both nonseptic groundwater (TN: 26%; TP: 5%) and septic-plume groundwater (TN: 4%; TP: 2%) deliveries of nutrients to the lakes. This work provides valuable information for environmental managers to target efforts to reduce nutrient loads to the Great Lakes, which could be transferred to other regions worldwide that are facing similar nutrient management challenges.

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Section: Study Area and Model Inputsmentioning

confidence: 99%

Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport

Wan,

Kendall,

Martin

et al. 2023

Environ. Sci. Technol.

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“…The coasts of Michigan harbor the most coastal wetlands of any Great Lakes state or province [100]. Much of the northern lower Michigan coast has high potential for groundwater discharge along the eastern coast of Lake Michigan and the northwestern coast of northern Lake Huron, related to the higher permeability of the glacial till and outwash deposits compared with other areas of shoreline [21,101] and to the height of the groundwater table relative to lake water levels [16]. These geologic conditions indicate that groundwater inputs can impact coastal wetland extent and ecosystem processes throughout the year.…”

Section: Groundwater In the Coastal Wetland Sectormentioning

confidence: 99%

Groundwater in Crisis? Addressing Groundwater Challenges in Michigan (USA) as a Template for the Great Lakes

et al. 2022

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Groundwater historically has been a critical but understudied, underfunded, and underappreciated natural resource, although recent challenges associated with both groundwater quantity and quality have raised its profile. This is particularly true in the Laurentian Great Lakes (LGL) region, where the rich abundance of surface water results in the perception of an unlimited water supply but limited attention on groundwater resources. As a consequence, groundwater management recommendations in the LGL have been severely constrained by our lack of information. To address this information gap, a virtual summit was held in June 2021 that included invited participants from local, state, and federal government entities, universities, non-governmental organizations, and private firms in the region. Both technical (e.g., hydrologists, geologists, ecologists) and policy experts were included, and participants were assigned to an agricultural, urban, or coastal wetland breakout group in advance, based on their expertise. The overall goals of this groundwater summit were fourfold: (1) inventory the key (grand) challenges facing groundwater in Michigan; (2) identify the knowledge gaps and scientific needs, as well as policy recommendations, associated with these challenges; (3) construct a set of conceptual models that elucidate these challenges; and (4) develop a list of (tractable) next steps that can be taken to address these challenges. Absent this type of information, the sustainability of this critical resource is imperiled.

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“…Trace elements, , mercury, , and nutrients , are examples of redox-sensitive inorganic contaminants of concern in coastal systems. While previous studies have shown that their fate and transport are impacted by transient tidal forcings , and terrestrial groundwater discharge, − the impact of varying wave forcing remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Effect of Transient Wave Forcing on the Behavior of Arsenic in a Nearshore Aquifer

Rakhimbekova

O'Carroll

Andersen

et al. 2018

Environ. Sci. Technol.

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Groundwater–coastal water interactions influence the fate of inorganic chemicals in nearshore aquifers and their flux to receiving coastal waters. This study evaluates the impact of variable wave conditions on the geochemical changes and distribution of mobile arsenic (As) in a nearshore aquifer. Field measurements in a sandy nearshore aquifer on Lake Erie, Canada, are presented with geochemical changes analyzed over a period of high waves. A numerical model of wave-induced groundwater flow dynamics, validated against field data, is used to provide insight into the physical flow processes underlying the observed geochemical changes. Rapid changes in dissolved As, Fe, Mn, and S demonstrate the importance of reactions as well as dynamic transport in controlling the behavior of reactive species, especially those that are redox sensitive. Field data suggest the presence of sediment traps, which under certain hydrological and geochemical conditions may result in a “hot moment” with episodic release of As. The study provides new insight into factors controlling the fate of reactive species in dynamic coastal environments as required to better predict chemical fluxes to coastal waters. Additionally, it highlights the need to pay particular attention to “hot moments” for reaction and transport caused by storms and waves.

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Direct groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States

Cited by 21 publications

References 73 publications

Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport

Important Role of Overland Flows and Tile Field Pathways in Nutrient Transport

Groundwater in Crisis? Addressing Groundwater Challenges in Michigan (USA) as a Template for the Great Lakes

Effect of Transient Wave Forcing on the Behavior of Arsenic in a Nearshore Aquifer

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