Estimation of nitrogen and phosphorus fluxes into a Barrier Island lagoon via meteoric groundwater discharge

Al-Taliby, Wissam; Pandit, Ashok K.

doi:10.1016/j.scitotenv.2023.163927

Cited by 2 publications

(3 citation statements)

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“…Seawater enters the lagoon mainly through the inlets (Figure 1). Due to the ongoing mixing of seawater and freshwater, the IRLS water is brackish, and its salinity may vary between 21 -31 (Al-Taliby and Pandit, 2023). Owing to the presence of the Barrier Island that constrains the connection of the lagoon to the Atlantic Ocean, all three lagoons in the system are microtidal, with a tidal range not exceeding 10 cm.…”

Section: Site Hydrogeology and Hydrologymentioning

confidence: 99%

“…The last few decades have witnessed the advent of several approaches and techniques to quantify SGD including seepage meters studies (Belanger and Walker, 1990;Michael et al, 2003;Taniguchi et al, 2006), radon and radium isotopes such as 223,224,226,228 Ra and 220,222 Rn as geochemical tracers (Cable et al, 1996;Moore, 1996;Burnett et al, 2001;Chanyotha et al, 2014;Cabral et al, 2023), hydrogeological groundwater modeling (Oberdorfer, 2003;Al-Taliby et al, 2016;Russoniello et al, 2018;Evans et al, 2020;Al-Taliby and Pandit, 2023), thermal imaging using infrared sensors (Johnson et al, 2008;Wilson and Rocha, 2012), and geophysical methods like electrical resistivity (Swarzenski et al, 2006;Dimova et al, 2012). The majority of SGD flux measurement research employed Ra and Rn isotopes and seepage meters (Burnett et al, 2006;Santos et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Hydrogeologic modeling easily enables the incorporation of meteoric sources of groundwater and thus provides a good tool for tracking and quantifying TGD. Hydrogeologic modeling has been used in fewer research studies to quantify SGD (Kaleris et al, 2002;Langevin, 2003;Oberdorfer, 2003;Russoniello et al, 2018;Evans et al, 2020;Al-Taliby and Pandit, 2023). To properly account for density effects in coastal aquifers, some of the numerical modeling studies dedicated to SGD research have utilized variable-density models, albeit most of them (Kaleris et al, 2002;Langevin, 2003;Smith and Zawadzki, 2003;Evans et al, 2020) have concentrated on calculating the total SGD rate and not the fresh component (TGD), which is the main conduit that contributes new SGD-born terrestrial nutrients to coastal waters.…”

Section: Introductionmentioning

confidence: 99%

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Groundwater nutrient loading into the northern Indian River lagoon: measurements and modeling

Al-Taliby,

Mamoua,

Pandit

et al. 2023

Front. Mar. Sci.

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The Indian River Lagoon System (IRLS) has been impacted by the surrounding development, leading to excessive nutrient loads that have resulted in frequent and prolonged phytoplankton blooms in the northern reaches. Our study focused on estimating terrestrial groundwater discharge (TGD) and associated nutrient loads by combining field measurements and hydrogeologic modeling at four transects: Eau Gallie (EGT), River Walk (RWT), Banana River (BRT), and Mosquito Lagoon (MLT) across the IRLS. Multiple monitoring stations were installed to collect groundwater and surface water levels, salinity, and nutrient concentrations during 2014-2015. Samples were analyzed for dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). Numerical modeling was accomplished using SEAWAT to simulate TGD rates, whereas nutrient loads were calculated by multiplying simulated TGD by measured concentrations. TGD rates and nutrient loads were also estimated specifically for the “near-shore zone” along each transect. The effect of recharge from underlying Hawthorn Formation was also evaluated by incorporating estimated recharge rates into the models. Porewater and lagoon water samples showed that ammonium predominated over (NO2+NO3) and PO4 at all sites, resulting in DIN/DIP ratio surpassing the Redfield ratio. Low nitrite/nitrate, coupled with elevated ammonium concentrations at RWT, BRT, and MLT, may be attributed to biogeochemical transformations catalyzed by mangroves and wetlands. Simulated TGD showed mild temporal but significant spatial variation, especially between EGT and RWT compared to BRT and MLT. The highest average TGD of 0.73 and 0.77 m3/d.m occurred at RWT and EGT, respectively, whereas the lowest rates were predicted at BRT and MLT. The highest estimated average DIN loads of 507 and 428 g/yr.m were received at EGT and RWT, respectively, whereas MLT and BRT exhibited lower loads. The DIP loads were remarkably lower than the DIN loads and were significantly different in space and time between sites. Elevated DIN combined with reduced DIP resulted in DIN/DIP exceeding the Redfield ratio, thereby encouraging the blooming of harmful algae. Although the majority of seepage occurs through the near-shore zone, small amounts are received along the entire transect at all sites. The Hawthorn Formation does not contribute significant recharge to the aquifer at the transect locations.

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Section: Site Hydrogeology and Hydrologymentioning

confidence: 99%