Submarine groundwater discharge is an important net source of light and middle REEs to coastal waters of the Indian River Lagoon, Florida, USA

Johannesson, Karen H.; Chevis, Darren A.; Burdige, David J.; Cable, Jaye E.; Martin, Jonathan B.; Roy, Moutusi

doi:10.1016/j.gca.2010.11.005

Cited by 100 publications

(113 citation statements)

References 111 publications

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“…Budgetary estimates from diffuse benthic REE fluxes, such as SGD or from sedimentary pore water Greaves et al, 1999;Haley and Klinkhammer, 2003;Tachikawa et al, 2003;Johannesson and Burdige, 2007;Schacht et al, 2010;Johannesson et al, 2011Johannesson et al, , 2017Abbott et al, 2015a;Fröllje et al, 2016), suggest that they may dominate the flux of REEs to the oceans. Importantly, such diffuse, or at least hard to quantify, sources are consistent with deep-water isopycnal mixing of ε Nd signals off margins that cannot be explained through surface water sources (Grasse et al, 2012;Grenier et al, 2013).…”

Section: Modern Ocean Rees and Nd Isotopesmentioning

confidence: 99%

The Impact of Benthic Processes on Rare Earth Element and Neodymium Isotope Distributions in the Oceans

Haley

Abbott

et al. 2017

Front. Mar. Sci.

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Neodymium (Nd) isotopes are considered a valuable tracer of modern and past ocean circulation. However, the promise of Nd isotope as a water mass tracer is hindered because there is not an entirely self-consistent model of the marine geochemical cycle of rare earth elements (REEs, of which Nd is one). That is, the prevailing mechanisms to describe the distributions of elemental and isotopic Nd are not completely reconciled. Here, we use published [Nd] and Nd isotope data to examine the prevailing model assumptions, and further compare these data to emergent alternative models that emphasize benthic processes in controlling the cycle of marine REEs and Nd isotopes. Our conclusion is that changing from a "top-down" driven model for REE cycling to one of a "bottom-up" benthic source model can provide consistent interpretations of these data for both elemental and isotopic Nd distributions. We discuss the implications such a benthic flux model carries for interpretation of Nd isotope data as a tracer for understanding modern and past changes in ocean circulation.

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Section: Modern Ocean Rees and Nd Isotopesmentioning

confidence: 99%

The Impact of Benthic Processes on Rare Earth Element and Neodymium Isotope Distributions in the Oceans

Haley

Abbott

et al. 2017

Front. Mar. Sci.

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“…Specifically, Moore (2010) reported that the annual average SGD flux to the South Atlantic Bight on the southeastern coast of the U.S.A. is three times greater than riverine supply in this region. Furthermore, SGD has also been reported to be an important source of nutrients and trace elements to the coastal ocean (Kelly and Moran, 2002;Duncan and Shaw, 2003;Charette and Sholkovitz, 2006;Johannesson et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Submarine groundwater discharge of rare earth elements to a tidally-mixed estuary in Southern Rhode Island

et al. 2015

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a b s t r a c tRare earth element (REE) concentrations were analyzed in surface water and submarine groundwater within the Pettaquamscutt Estuary, located on the western edge of Narragansett Bay in Rhode Island. These water samples were collected along the salinity gradient of the estuary. Rare earth element concentrations in the majority of the groundwater samples are substantially higher than their concentrations in the surface waters. In particular, Nd concentrations in groundwater range from 0.43 nmol kg −1 up to 198 nmol kg −1 (mean ± SD = 42.1 ± 87.2 nmol kg −1 ), whereas Nd concentrations range between 259 pmol kg −1 and 649 pmol kg −1 (mean ± SD = 421 ± 149 pmol kg −1 ) in surface waters from the estuary, which is, on average, 100 fold lower than Nd in the groundwaters. Groundwater samples all exhibit broadly similar middle REE (MREE) enriched shalenormalized REE patterns, despite the wide variation in pH of these natural waters (4.87 ≤ pH ≤ 8.13). The similarity of the shale-normalized REE patterns across the observed pH range suggests that weathering of accessory minerals, such as apatite, and/or precipitation of LREE enriched secondary phosphate minerals controls groundwater REE concentrations and fractionation patterns. More specifically, geochemical mixing models suggest that the REE fractionation patterns of the surface waters may be controlled by REE phosphate mineral precipitation during the mixing of groundwater and stream water with incoming water from the Rhode Island Sound. The estimated SGD (Submarine Groundwater Discharge) of Nd to the Pettaquamscutt Estuary is 26 ± 11 mmol Nd day −1 , which is in reasonable agreement with the Nd flux of the primary surface water source to the estuary, the Gilbert Stuart Stream (i.e., 36 mmol day −1 ), and of the same order of magnitude for a site in Florida.

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“…Biogeochemical reactions such as ion exchange, dissolution and precipitation, and metal redox cycling occur in the mixing zone between meteoric and saline groundwaters (the so-called "subterranean estuary," or STE, Moore, 1999), resulting in a brackish SGD end-member that is very different in composition from either 100 of its end-members (Charette and Sholkovitz, 2006;Shaw et al, 1998). Given a sufficient degree of enrichment for a particular constituent, SGD can represent a significant chemical flux, even on oceanic scales, as has been shown for Nd (Johannesson and Burdige, 2007;Johannesson et al, 2011), Fe (Windom et al, 2006), and Ra Moore, 2010). The demonstration of large SGD-driven fluxes of Ba and Ra in the Bengal Basin (Moore, 1997) spurred studies 105 identifying a substantial Sr flux in that region Dowling et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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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Submarine groundwater discharge is an important net source of light and middle REEs to coastal waters of the Indian River Lagoon, Florida, USA

Cited by 100 publications

References 111 publications

The Impact of Benthic Processes on Rare Earth Element and Neodymium Isotope Distributions in the Oceans

The Impact of Benthic Processes on Rare Earth Element and Neodymium Isotope Distributions in the Oceans

Submarine groundwater discharge of rare earth elements to a tidally-mixed estuary in Southern Rhode Island

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

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