Effect of land use and groundwater flow path on submarine groundwater discharge nutrient flux

Bishop, James M.; Glenn, Craig R.; Amato, Daniel W.; Dulai, Henrietta

doi:10.1016/j.ejrh.2015.10.008

Cited by 71 publications

(74 citation statements)

References 37 publications

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“…Following the hydrological characterization by Bishop et al [53], SGD inputs were present at all locations as evidenced by reduced salinity and elevated radon in nearshore waters relative to offshore sites during the period of this study. Further, gradients were observed in marine surface water at all locations with lower salinity and higher nutrient concentrations at nearshore sites compared to offshore sites.…”

Section: Resultssupporting

confidence: 58%

“…At the NE corner of the bay, salt marshes at Keālia Pond National Wildlife Refuge provide a buffer between surgarcane fields and a sandy beach. A concurrent study, Bishop et al [53] provided estimates of SGD-derived nutrient fluxes, groundwater flow paths, and land use assessments for all these study locations.…”

Section: Methodsmentioning

confidence: 99%

“…The purpose of this study was to test for links among land use, N content of CGW, water quality of marine surface waters, and reef biota at locations where SGD input and associated nutrient sources were characterized via a concurrent study [53]. Using common marine algae as bioindicators of available nitrogen in coastal settings, we hypothesized that algal tissue N (δ 15 N and N %) would be related to the dominant N source and amount of biologically available N in CGW and marine surface waters of Maui.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Submarine Groundwater Discharge on Marine Water Quality and Reef Biota of Maui

et al. 2016

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Generally unseen and infrequently measured, submarine groundwater discharge (SGD) can transport potentially large loads of nutrients and other land-based contaminants to coastal ecosystems. To examine this linkage we employed algal bioassays, benthic community analysis, and geochemical methods to examine water quality and community parameters of nearshore reefs adjacent to a variety of potential, land-based nutrient sources on Maui. Three common reef algae, Acanthophora spicifera, Hypnea musciformis, and Ulva spp. were collected and/or deployed at six locations with SGD. Algal tissue nitrogen (N) parameters (δ15N, N %, and C:N) were compared with nutrient and δ15N-nitrate values of coastal groundwater and nearshore surface water at all locations. Benthic community composition was estimated for ten 10-m transects per location. Reefs adjacent to sugarcane farms had the greatest abundance of macroalgae, low species diversity, and the highest concentrations of N in algal tissues, coastal groundwater, and marine surface waters compared to locations with low anthropogenic impact. Based on δ15N values of algal tissues, we estimate ca. 0.31 km2 of Kahului Bay is impacted by effluent injected underground at the Kahului Wastewater Reclamation Facility (WRF); this region is barren of corals and almost entirely dominated by colonial zoanthids. Significant correlations among parameters of algal tissue N with adjacent surface and coastal groundwater N indicate that these bioassays provided a useful measure of nutrient source and loading. A conceptual model that uses Ulva spp. tissue δ15N and N % to identify potential N source(s) and relative N loading is proposed for Hawaiʻi. These results indicate that SGD can be a significant transport pathway for land-based nutrients with important biogeochemical and ecological implications in tropical, oceanic islands.

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Section: Resultssupporting

confidence: 58%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Submarine Groundwater Discharge on Marine Water Quality and Reef Biota of Maui

et al. 2016

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“…Despite being situated in an oligotrophic region with naturally occurring, low nutrient concentrations, anthropogenic nutrient loading to coastal waters via sustained SGD is driving nearshore eutrophication (Dailer et al, 2010Bishop et al, 2015;Amato et al, 2016;Fackrell et al, 2016), with algal δ 15 N signatures at Kahekili Beach Park indicative of wastewater effluent (Dailer et al, 2010. In response, there has been a shift in benthic cover from abundant corals to turf or macro-algae over the last two decades.…”

Section: Discussionmentioning

confidence: 99%

Carbonate system parameters of an algal-dominated reef along West Maui

et al. 2018

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Abstract. Constraining coral reef metabolism and carbon chemistry dynamics are fundamental for understanding and predicting reef vulnerability to rising coastal CO 2 concentrations and decreasing seawater pH. However, few studies exist along reefs occupying densely inhabited shorelines with known input from land-based sources of pollution. The shallow coral reefs off Kahekili, West Maui, are exposed to nutrient-enriched, low-pH submarine groundwater discharge (SGD) and are particularly vulnerable to the compounding stressors from land-based sources of pollution and lower seawater pH. To constrain the carbonate chemistry system, nutrients and carbonate chemistry were measured along the Kahekili reef flat every 4 h over a 6-day sampling period in March 2016. Abiotic process -primarily SGD fluxes -controlled the carbonate chemistry adjacent to the primary SGD vent site, with nutrient-laden freshwater decreasing pH levels and favoring undersaturated aragonite saturation ( arag ) conditions. In contrast, diurnal variability in the carbonate chemistry at other sites along the reef flat was driven by reef community metabolism. Superimposed on the diurnal signal was a transition during the second sampling period to a surplus of total alkalinity (TA) and dissolved inorganic carbon (DIC) compared to ocean endmember TA and DIC measurements. A shift from positive net community production and positive net community calcification to negative net community production and negative net community calcification was identified. This transition occurred during a period of increased SGD-driven nutrient loading, lower wave height, and reduced current speeds. This detailed study of carbon chemistry dynamics highlights the need to incorporate local effects of nearshore oceanographic processes into predictions of coral reef vulnerability and resilience.

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“…Several cases studies have been approached using geochemical tools to quantify nutrient fluxes from groundwater discharge both in continental areas [4,9,18,19] or in islands [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Nitrates in Groundwater Discharges from the Azores Archipelago: Occurrence and Fluxes to Coastal Waters

Cruz

Andrade

Pacheco³

et al. 2017

Water

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Abstract:Groundwater discharge is an important vector of chemical fluxes to the ocean environment, and as the concentration of nutrients is often higher in discharging groundwater, the deterioration of water quality in the receiving environment can be the result. The main objective of the present paper is to estimate the total NO 3 flux to coastal water bodies due to groundwater discharge in the volcanic Azores archipelago (Portugal). Therefore, 78 springs discharging from perched-water bodies have been monitored since 2003, corresponding to cold (mean = 14.9 • C) and low mineralized (47.2-583 µS/cm) groundwater from the sodium-bicarbonate to sodium-chloride water types. A set of 36 wells was also monitored, presenting groundwater with a higher mineralization. The nitrate content in springs range between 0.02 and 37.4 mg/L, and the most enriched samples are associated to the impact of agricultural activities. The total groundwater NO 3 flux to the ocean is estimated in the range of 5.23 × 10 3 to 190.6 × 10 3 mol/km 2 /a (∑ =~523 × 10 3 mol/km 2 /a), exceeding the total flux associated to surface runoff (∑ =~281 × 10 3 mol/km 2 /a). In the majority of the islands, the estimated fluxes are higher than runoff fluxes, with the exception of Pico (47.2%), Corvo (46%) and Faial (7.2%). The total N-NO 3 flux estimated in the Azores (~118.9 × 10 3 mol/km 2 /a) is in the lower range of estimates made in other volcanic islands.

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Effect of land use and groundwater flow path on submarine groundwater discharge nutrient flux

Cited by 71 publications

References 37 publications

Impact of Submarine Groundwater Discharge on Marine Water Quality and Reef Biota of Maui

Impact of Submarine Groundwater Discharge on Marine Water Quality and Reef Biota of Maui

Carbonate system parameters of an algal-dominated reef along West Maui

Nitrates in Groundwater Discharges from the Azores Archipelago: Occurrence and Fluxes to Coastal Waters

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