Source partitioning of anthropogenic groundwater nitrogen in a mixed-use landscape, Tutuila, American Samoa

Shuler, Christopher K.; El‐Kadi, Aly I.; Dulai, Henrietta; Glenn, Craig R.; Fackrell, Joseph K.

doi:10.1007/s10040-017-1617-x

Cited by 18 publications

(40 citation statements)

References 37 publications

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“…The three primary anthropogenic land use types (i.e. nutrient sources) previously identified on Tutuila include: On-Site wastewater Disposal Systems (OSDS), smallscale pig farms, and agricultural fertilizers (Shuler et al 2017).…”

Section: Study Locationmentioning

confidence: 99%

“…The SWB2 component represents the water budget model used to determine water discharge rates and observed streamflow and nutrient fluxes are from field data used to calibrate and validate the model. The DIN release rates were initially parameterized with values from Shuler et al (2017) and final rates were determined through loading model calibration. Steps marked with Xs indicate multiplication of values used to calculate derived components…”

Section: Modeling Frameworkmentioning

confidence: 99%

“…We obtained existing water quality data from stream and coastal spring samples taken throughout Tutuila by Comeros-Raynal et al (2019), Shuler et al (2017. Stream sampling data from Comeros-Raynal (2019) were collected from 38 individual stream sites for a one-year period from September 2016 to September 2017 (Fig 3), and consisted of a total of 424 individual stream samples.…”

Section: Water Sampling and Nutrient Concentrationsmentioning

confidence: 99%

“…We grouped additional coastal spring data collected at 31 locations from 2013 and 2018 (Shuler et al 2017 with the Comeros-Raynal coastal spring data to supplement the groundwater end-member dataset (Fig 3) for a total of 81 coastal spring samples. All stream and coastal spring samples were analyzed for nitrate (NO3 -), nitrite (NO2 -) and ammonium (NH4 + ) concentrations, which when summed, represent the DIN concentration.…”

Section: Water Sampling and Nutrient Concentrationsmentioning

confidence: 99%

“…We considered four terrestrial DIN sources as drivers for the model: three anthropogenic sources (OSDS, piggeries, and agricultural fertilizer input), and DIN from natural sources such as leaf litter and animal waste (Shuler et al 2017). To resolve the spatial distribution of anthropogenic DIN sources to the watershed scale, we obtained the locations of every OSDS unit, every pig, and all known agricultural land on the island and geospatially intersected these anthropogenic DIN sources with watershed boundaries (Fig 4).…”

Section: Step 3 Identification Of Terrestrial Din Sourcesmentioning

confidence: 99%

See 4 more Smart Citations

Ridge to Reef Management Implications for the Development of an Open-Source Dissolved Inorganic Nitrogen Loading Model in American Samoa

Shuler

Comeros-Raynal

2020

Preprint

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Excessive nutrient discharge to tropical island coastlines drives eutrophication and algal blooms with significant implications for reef ecosystem condition and provision of ecosystem services.Management actions to address nutrient pollution in coastal ecosystems include setting water quality standards for discharging surface waters. However, these standards do not account for the effects of groundwater discharge, variability in flow, or dilution, all of which may influence assessment of true nutrient impacts on nearshore reef habitats. We developed a method to estimate dissolved inorganic nitrogen (DIN) loads to coastal zones by integrating commonly available datasets within a geospatial modeling framework for Tutuila, American Samoa. The DIN loading model integrated an open-source water budget model, water sampling results, and publically available streamflow data to predict watershed-scale DIN loading to the island's entire coastline. When compared to surface water pathways, submarine groundwater discharge (SGD) was determined to be the most important coastal delivery mechanism of terrigenous DIN, which supports findings from other tropical islands. Onsite wastewater disposal systems were also found to be the primary anthropogenic sources DIN to coastal waters. Our island-wide DIN loading model provides a simple and robust metric to define spatially-explicit sources and delivery mechanisms of nutrient pollution to nearshore reef habitats. Understanding the sources and primary transport modes of inorganic nitrogen to nearshore reef ecosystems can have significant implications for place-based management interventions aimed at increasing the adaptive capacity of unique island ecosystems to environmental variation and disturbances.

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Section: Study Locationmentioning

confidence: 99%

Section: Modeling Frameworkmentioning

confidence: 99%

Section: Water Sampling and Nutrient Concentrationsmentioning

confidence: 99%

Section: Water Sampling and Nutrient Concentrationsmentioning

confidence: 99%

Section: Step 3 Identification Of Terrestrial Din Sourcesmentioning

confidence: 99%

See 3 more Smart Citations

Ridge to Reef Management Implications for the Development of an Open-Source Dissolved Inorganic Nitrogen Loading Model in American Samoa

Shuler

Comeros-Raynal

2020

Preprint

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Risk to native marine macroalgae from land‐use and climate change‐related modifications to groundwater discharge in Hawaiʻi

Dulai

Smith

Amato

et al. 2021

Limnol Oceanogr Letters

Self Cite

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Coastal groundwater-dependent ecosystems and associated species, including native macroalgae, are highly adapted to the lowered salinity and nutrient subsidies of natural flows of submarine groundwater discharge (SGD). However, with climate and land-use change-induced shifts in SGD, invasive macroalgae are outcompeting native species, with drastic implications for these important ecosystems. This article contributes to a synthetic understanding of these processes by providing a salient case study from Oʻahu, Hawaiʻi, and by reviewing evidence on the links between SGD and the composition of macroalgal communities. Results point to the critical importance of sound land, water, and wastewater management policies to reduce impacts on SGD and native coastal groundwater-dependent ecosystems, particularly in the context of climate change.

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Coastal Tourism and Its Influence on Wastewater Nitrogen Loading: A Barrier Island Case Study

O’Driscoll

Bean

Mahoney³

et al. 2019

Environmental Management

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Source partitioning of anthropogenic groundwater nitrogen in a mixed-use landscape, Tutuila, American Samoa

Cited by 18 publications

References 37 publications

Ridge to Reef Management Implications for the Development of an Open-Source Dissolved Inorganic Nitrogen Loading Model in American Samoa

Ridge to Reef Management Implications for the Development of an Open-Source Dissolved Inorganic Nitrogen Loading Model in American Samoa

Risk to native marine macroalgae from land‐use and climate change‐related modifications to groundwater discharge in Hawaiʻi

Coastal Tourism and Its Influence on Wastewater Nitrogen Loading: A Barrier Island Case Study

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