pH-Dependent iron oxide precipitation in a subterranean estuary

Spiteri, Claudette; Regnier, Pierre; Slomp, Caroline P.; Charette, Matthew A.

doi:10.1016/j.gexplo.2005.08.084

Cited by 94 publications

(88 citation statements)

References 10 publications

(16 reference statements)

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“…These values are consistent with the extensive intrusion of seawater that can occur in karst aquifers and the large volume of fresh and saline water movement in such systems. The mixed brackish/saline water discharging in many coastal karst systems is chemically different than either the meteoric or surface seawater due to reactions in the subterranean estuary (Slomp and Van Cappellen, 2004;Spiteri et al, 2006) and should be explicitly determined as this water may have significant impact on coastal ecosystems (Moore, 2010). Young et al (2008) found that the Celestun Lagoon on the northwest corner of the Yucatan Peninsula had different groundwater sources, (1) a low salinity, low radium and high nitrate source, and (2) a brackish source with high radium and less nitrate.…”

Section: Sgd: Ojos and Beach Facementioning

confidence: 99%

Composition and fluxes of submarine groundwater along the Caribbean coast of the Yucatan Peninsula

Null

Knee

Crook

et al. 2014

Continental Shelf Research

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a b s t r a c tSubmarine groundwater discharge (SGD) to the coastal environment along the eastern Yucatan Peninsula, Quintana Roo, Mexico was investigated using a combination of tracer mass balances and analytical solutions. Two distinct submarine groundwater sources including water from the unconfined surficial aquifer discharging at the beach face and water from a deeper aquifer discharging nearshore through submarine springs (ojos) were identified. The groundwater of nearshore ojos was saline and significantly enriched in short-lived radium isotopes ( 223 Ra, 224 Ra) relative to the unconfined aquifer beach face groundwater. We estimated SGD from ojos using 223 Ra and used a salinity mass balance to estimate the freshwater discharge at the beach face. Analytical calculations were also used to estimate wave set-up and tidally driven saline seepage into the surf zone and were compared to the salinity-based freshwater discharge estimates. ). Discharge at the beach face was in the range of 3.3-8.5 m 3 d À 1 m À 1 for freshwater and 2.7 m 3 d À 1 m À 1 for saline water based on the salinity mass balance and wave-and tidally-driven discharge, respectively. Although discharge from the ojos was larger in volume than discharge from the unconfined aquifer at the beach face, dissolved inorganic nitrogen (DIN) was significantly higher in beach groundwater; thus, discharge of this unconfined beach aquifer groundwater contributed significantly to total DIN loading to the coast. DIN fluxes were up to 9.9 mol d À 1 m À 1 from ojos and 2.1 mol d À 1 m À 1 from beach discharge and varied regionally along the 500 km coastline sampled. These results demonstrate the importance of considering the beach zone as a significant nutrient source to coastal waters for future management strategies regarding nutrient loading to reef environments and coastal development. This study also identifies the importance of understanding the connectivity of submarine spring discharge to the nearshore coastal environment and the impact of inland anthropogenic activities may have on coastal health.

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Section: Sgd: Ojos and Beach Facementioning

confidence: 99%

Composition and fluxes of submarine groundwater along the Caribbean coast of the Yucatan Peninsula

Null

Knee

Crook

et al. 2014

Continental Shelf Research

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“…The process controlling this removal is not obvious from the current dataset, although scavenging onto authigenic iron oxides may play a role (Andersson et al, 1994). Sorption by Fe-oxyhydroxides may be especially important in the STE, due to extensive 250 formation of such precipitates during mixing of meteoric and marine groundwaters (Charette et al, 2002;Charette et al, 2005;Spiteri et al, 2006). However, Sr removal from solution by this mechanism does not appear to be ubiquitous, given that Sr depletion was not evident at some sites where Fe precipitation has been clearly documented (e.g., Waquoit Bay and Great South Bay; Charette andSholkovitz, 2006, Beck et al, 2010).…”

Section: Sr In the Subterranean Estuary 240mentioning

confidence: 93%

Dissolved strontium in the subterranean estuary – Implications for the marine strontium isotope budget

Beck¹,

Charette²,

Cochran³

et al. 2013

Geochimica et Cosmochimica Acta

100

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15Submarine groundwater discharge (SGD) to the ocean supplies Sr with less radiogenic 87 Sr/ 86 Sr than seawater, and thus constitutes an important term in the Sr isotope budget in the modern ocean. However, few data exist for Sr in coastal groundwater or in the geochemically dynamic subterranean estuary (STE). We examined Sr concentrations and isotope ratios from nine globally-distributed coastal sites and characterized the behavior of Sr in the STE. Dissolved Sr 20 generally mixed conservatively in the STE, although large differences were observed in the meteoric groundwater end-member Sr concentrations among sites (0.1 -24 µM Sr). Strontium isotope exchange was observed in the STE at five of the sites studied, and invariably favored the meteoric groundwater end-member signature. Most of the observed isotope exchange occurred in the salinity range 5-15, and reached up to 40% exchange at salinity 10.

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“…They found a significant correlation between Fe and P in aquifer sediments, and suggested that the iron curtain could act as a natural permeable reactive barrier for in situ removal of chemical species such as phosphate (PO4-P) that have a strong affinity for Fe (hydr)oxides. Later, Spiteri et al [2006] used a reactive transport model to demonstrate that the iron curtain's formation is driven largely by pH (rather than redox) gradients, and that this process may be responsible for greatly reduced (PO4-P) transport to the coastal ocean via SGD.…”

Section: Metalsmentioning

confidence: 99%

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Robinson¹,

Xin²,

Santos³

et al. 2018

Advances in Water Resources

202

148

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Sustainable coastal resource management requires sound understanding of interactions between coastal unconfined aquifers and the ocean as these interactions influence the flux of chemicals to the coastal ocean and the availability of fresh groundwater resources. The importance of submarine groundwater discharge in delivering chemical fluxes to the coastal ocean and the critical role of the subterranean estuary (STE) in regulating these fluxes is well recognized. STEs are complex and dynamic systems exposed to various physical, hydrological, geological, and chemical conditions that act on disparate spatial and temporal scales. This paper provides a review of the effect of factors that influence flow and salt transport in STEs, evaluates current understanding on the interactions between these influences, and synthesizes understanding of drivers of nutrient, carbon, greenhouse gas, metal and organic contaminant fluxes to the ocean.Based on this review, key research needs are identified. While the effects of density and tides are well understood, episodic and longer-period forces as well as the interactions between multiple influences remain poorly understood. Many studies continue to focus on idealized nearshore aquifer systems and future work needs to consider real world complexities such as geological heterogeneities, and non-uniform and evolving alongshore and cross-shore morphology. There is also a significant need for multidisciplinary research to unravel the interactions between physical and biogeochemical processes in the STE, as most existing studies treat these processes in isolation. Better understanding of this complex and dynamic system can improve sustainable management of coastal water resources under the influence of anthropogenic pressures and climate change.

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pH-Dependent iron oxide precipitation in a subterranean estuary

Cited by 94 publications

References 10 publications

Composition and fluxes of submarine groundwater along the Caribbean coast of the Yucatan Peninsula

Composition and fluxes of submarine groundwater along the Caribbean coast of the Yucatan Peninsula

Dissolved strontium in the subterranean estuary – Implications for the marine strontium isotope budget

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

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