The influence of sediment sources on radium-derived estimates of Submarine Groundwater Discharge

Rodellas, Valentí; García-Orellana, Jordi; Masqué, Pere; Font-Muñoz, Joan S.

doi:10.1016/j.marchem.2015.02.010

Cited by 42 publications

(25 citation statements)

References 48 publications

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“…Submarine Groundwater Discharge (SGD) is an important component of the hydrological cycle in coastal aquifers and is a source of nutrients and micronutrients to coastal areas (Rengarajan and Sarma 2015, Rodellas et al 2015, Trezzi et al 2016. SGD is generally composed of a mixture between freshwater and circulated seawater, the latter of which is either recirculated through intertidal and subtidal sediments or derived from seawater intrusion which has infiltrated into depleted coastal aquifers (Burnett et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Influence of land use changes on submarine groundwater discharge

Rufí-Salís

García-Orellana

Cantero

et al. 2019

Environ. Res. Commun.

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The 20th century has been characterized by an exponential population growth, with a high density in coastal zones. The aim of this work is to study the impact of land use changes on the hydrological cycle, and possible consequences in marine environment. The study has focused on the relationship between coastal urbanisation and submarine groundwater discharge (SGD) that may cause an alteration in the biogeochemical cycles of marine ecosystems. An analysis of land use changes, historical salinities and nutrients data in the Maresme (Barcelona) coastal zone have revealed that the percentage of urban and forest zone land use has increased since 1990, corresponding to a decrease of nutrients in coastal waters through SGD. These impacts may cause changes in coastal biogeochemical cycles, like the decrease in chlorophyll concentrations. Results denote the correlation between land use, coastal aquifer dynamics and the effects of SGD in coastal environments.

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Section: Introductionmentioning

confidence: 99%

Influence of land use changes on submarine groundwater discharge

Rufí-Salís

García-Orellana

Cantero

et al. 2019

Environ. Res. Commun.

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“…In several areas of the world, this process has been recognized as an important pathway for the transport of chemical compounds, including: nutrients (e.g. Rodellas et al, 2015), metals (e.g. Windom et al, 2006;Trezzi et al, 2016), pollutants (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Calculated 223 Ra and 224 Ra xs diffusion rates amount to (2.2 ± 0.02) and (32 ± 2) dpm m -2 d -1 , respectively (Figure 5). These represent upper limits because during the experiment Ra was continuously removed from the water overlying the sediment core, thereby forcing diffusion by maximizing the gradient between the porewater and the overlying water.Diffusion-sourced 226 Ra and 228 Ra fluxes are locally insignificant because the rate of their production by Th parents is slow(Rodellas et al, 2015) relative to the residence time within Öregrundsgrepen. The 224 Ra xs diffusion rate is similar to that reported from the Venice Lagoon (32 dpm d -1 m -2 ;Garcia-Solsona et al, 2008) and Jamaica Bay (28 dpm d -1 m -2 ;Beck et al, 2007) but lower than that reported from Long Island Sound ( > 127 dpm m -2 d -1 ; Garcia Orellana et al, 2014) and the Port of Maó (110 dpm m -2 d -1 ;Rodellas et al, 2015).…”

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confidence: 99%

Submarine groundwater discharge at Forsmark, Gulf of Bothnia, provided by Ra isotopes

et al. 2017

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Submarine groundwater discharge (SGD) to the Gulf of Bothnia, Baltic Sea, has been believed to be insignificant from hydrological models, yet geochemical investigations of SGD in this basin are limited. In this study, 223 Ra, 224 Ra, 226 Ra, and 228 Ra have been complemented by stable δ 18 O and δ 2 Η isotopes to characterize and quantify SGD rates from the coast of Forsmark, Sweden to Öregrundsgrepen Strait (Gulf of Bothnia). In shallow bays, SGD has been traced using relations between Ra, δ 2 Η and δ 18 Ο isotopes and salinity. Zonal SGD from deformation zones, expressed as hydraulically conductive fractures, overlain by the Börstilåsen esker, a strip of conductive gravel sediment, have been traced through offshore 224 Ra xs and 226 Ra trends. On the basis of a 224 Ra xs mass balance, the SGD flow rate ranges from (5.5 ± 3.0) • 10 3 m 3 d-1 to (950 ± 520) • 10 3 m 3 d-1. These rates are up to two orders of magnitude higher than those determined from local hydrological models, which consider only the fresh component of SGD. From the divergence between the hydrological and 224 Ra xs models, it is inferred that the site is influenced by a component of recirculated seawater.

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“…Away from areas of river influence, diffuse groundwater seeps are an important nutrient source sustaining nearshore communities in the Mediterranean Sea (Basterretxea et al, 2010;Rodellas et al, 2015).…”

Section: Physical Environment and Phytoplankton Biomassmentioning

confidence: 99%

Cross-Shore Environmental Gradients in the Western Mediterranean Coast and Their Influence on Nearshore Phytoplankton Communities

et al. 2018

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During summer, when oligotrophic conditions prevail offshore in the Mediterranean Sea, enhanced phytoplankton stripes are often observed in nearshore waters. In this study, we examine the cross-shore hydrographic variability and the associated microbial plankton communities in this zone. Detailed cross-shore underway sampling at 47 coastal sites spread along the Balearic and Catalan coasts revealed the widespread existence of narrow bands of warm and decreased salinity water beholding high phytoplankton biomass (up to 50-fold vs. offshore chlorophyll). Most intense physical and biological anomalies along these transects were generally constrained to the first hundred meters from the shoreline (i.e., a transition zone starting at ∼400 m). We use Principal Component Analysis (PCA) and k-means cluster analysis to categorize temperature, salinity and chlorophyll (T, S and Chl) in three main types of cross-shore trends. Prevalence of exponential-shaped Chl trends was observed particularly in areas with shoreward directed winds (B1-type). The other two trends (B2 and B3) presented variations off the coast produced by alongshore structures like river plumes, city outfalls and other features. Exponential-shaped cross-shore chlorophyll distribution (B1-type) accumulated 90% of the total transect Chl variation in the first 367 ± 190 m from the shoreline, whereas this distance was variable in the other profile types. Repeated daily sampling at one site with this transect typology revealed that wind forcing variations produced fast response on cross-shore T and S properties. Chl was less sensitive to changes at this time-scale. Phytoplankton communities exhibited site-dependent responses to the nearshore environment. Pico-and nanoplankton assemblages, typically dominating coastal assemblages during summer in the Mediterranean Sea, showed lower cross-shore variation. Conversely, larger response to nearshore conditions was observed in microplankton populations. These larger cells, represented by dinoflagellates, cryptophytes and diatoms, were able Basterretxea et al.Cross-Shore Gradients in Coastal Phytoplankton to actively exploit the nearshore conditions constituting an independent and distinct assemblage from that one prevailing offshore. Our results suggest that despite the importance of local-scale processes in determining biotic structure, some common patterns emerge providing clues on the main drivers of this nearshore niche.

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The influence of sediment sources on radium-derived estimates of Submarine Groundwater Discharge

Cited by 42 publications

References 48 publications

Influence of land use changes on submarine groundwater discharge

Influence of land use changes on submarine groundwater discharge

Submarine groundwater discharge at Forsmark, Gulf of Bothnia, provided by Ra isotopes

Cross-Shore Environmental Gradients in the Western Mediterranean Coast and Their Influence on Nearshore Phytoplankton Communities

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