New insights into the hydrogeology and groundwater flow in the Great Barrier Reef catchment, Australia, revealed through 3D modelling

Shishaye, Haile Arefayne; Tait, Douglas R.; Befus, K. M.; Maher, Damien T.; Reading, Michael J.

doi:10.1016/j.ejrh.2020.100708

Cited by 9 publications

(12 citation statements)

References 34 publications

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“…34 Fresh groundwater inputs were also likely higher in the Wet Tropics region due to greater recharge and often steeper hydraulic gradients. 36,37 However, low seawater concentrations of 226 Ra (Supporting Figure S2) compared to coastal porewater concentrations (Supporting Figure S3) and previous inland concentrations 38 suggest low fresh groundwater inputs.…”

Section: ■ Results and Discussionmentioning

confidence: 91%

“…The steeper salinity trend in the northern sites was likely due to greater coastal influxes of freshwater in the Wet Tropics region where river inputs are double those in the southern transect area . Fresh groundwater inputs were also likely higher in the Wet Tropics region due to greater recharge and often steeper hydraulic gradients. , However, low seawater concentrations of 226 Ra (Supporting Figure S2) compared to coastal porewater concentrations (Supporting Figure S3) and previous inland concentrations suggest low fresh groundwater inputs.…”

Section: Resultsmentioning

confidence: 99%

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Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Tait,

Santos,

Lamontagne

et al. 2023

Environ. Sci. Technol.

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Rivers are often assumed to be the main source of nutrients triggering eutrophication in the Great Barrier Reef (GBR). However, existing nutrient budgets suggest a major missing source of nitrogen and phosphorus sustaining primary production. Here, we used radium isotopes to resolve submarine groundwater discharge (SGD)-derived, shelf-scale nutrient inputs to the GBR. The total SGD was ∼10−15 times greater than average river inputs, with nearshore groundwater discharge accounting for ∼30% of this. Total SGD accounted for >30% of all known dissolved inorganic N and >60% of inorganic P inputs and exceeded regional river inputs. However, SGD was only a small proportion of the nutrients necessary to sustain primary productivity, suggesting that internal recycling processes still dominate the nutrient budget. With millions of dollars spent managing surface water nutrient inputs to reef systems globally, we argue for a shift in the focus of management to safeguard reefs from the impacts of excess nutrients.

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Section: ■ Results and Discussionmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Tait,

Santos,

Lamontagne

et al. 2023

Environ. Sci. Technol.

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“…Groundwater could also potentially account for coastal CH 4 hotspots. The region has a highly dynamic groundwater exchange processes, including submarine springs discharging from complex aquifer systems (Shishaye et al., 2020; Stieglitz, 2005) and tidally driven groundwater exchange along beaches and mangroves (Santos et al., 2010, Tait et al., 2017). While groundwater discharge is often a source of CH 4 (and other GHGs) to estuaries and coastal waters (Porubsky et al., 2014), it remains unclear if this the case here.…”

Section: Discussionmentioning

confidence: 99%

Spatial Distribution of CO₂, CH₄, and N₂O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis

Reading

Maher

Santos

et al. 2021

Geophysical Research Letters

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Atmospheric concentrations of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) have increased by 47%, 160%, and 22% compared to pre-industrial levels, respectively, and are largely responsible for increasing trends in global temperatures (Burke et al., 2018). While CO 2 is the more abundant greenhouse gas, CH 4 and N 2 O can contribute disproportionately to radiative forcing due to their powerful warming potentials (~25 and 300 times more potent than CO 2 on a weight/weight basis over a 100-year time-frame) (Stocker et al., 2013). The open ocean plays a pivotal role in regulating atmospheric greenhouse gas dynamics, usually acting as a sink of CO 2 (−2400 Tg CO 2 y −1 ; Le Quéré et al., 2018) and a source of CH 4 (14 Tg y −1 ; Saunois et al., 2020) and N 2 O (3.4 Tg y −1 ; Tian et al., 2020). However, substantial uncertainties remain in the respective CO 2 , CH 4 and N 2 O budgets due to variation in regional environmental factors (e.g., upwelling regions, oxygen depletion zones, cryptic sources, and processes) that can influence GHG dynamics. Additionally, stronger benthic-pelagic coupling signals in shallower waters and terrestrial carbon and nitrogen Abstract Methane (CH 4 ) and nitrous oxide (N 2 O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO 2 ) and CH 4 (with δ 13 C-CO 2 and δ 13 C-CH 4 isotope fractions) and N 2 O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO 2 (379-589 μatm) was oversaturated due to calcification and riverine sources, as indicated by depleted δ 13 C-CO 2 values. CH 4 (1.5-13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted δ 13 C-CH 4 and probable offshore aerobic production. N 2 O (5.5-6.6 nM) was generally undersaturated, with uptake highest near the coast. Daily CO 2 emissions were 5826 ± 1191 tonnes, with CO 2 equivalent ( eq ) N 2 O uptake (191 ± 44 tonnes) offsetting 3.3% of CO 2 or 89% of CH 4eq (214 ± 45 tonnes) emissions based on 20-year global warming potentials. The GBR was a slight CO 2 and CH 4 source and N 2 O sink during our study. However, further work is required to constrain diurnal, seasonal, and spatial dynamics. Plain Language SummaryThe oceans absorb carbon dioxide from the atmosphere but can emit the more potent greenhouse gases of methane and nitrous oxide. Large uncertainties remain in oceanic greenhouse gas budgets due to variation in regional emissions from environmental factors such as upwelling, oxygen depletion, continental nutrient inputs and sedimentary processes in coastal areas. Here, we measured dissolved carbon dioxide, methane, and nitrous oxide in the Great Barrier Reef lagoon to characterize spatial distributions, drivers, and emissions. The lagoon was a minor source of carbon dioxide and methane to the atmosphere, with higher emissions near the coast. The primary carbon dioxide source was calcification, where carbon dioxide is produced when organisms build calcium carbonate skeletons. Methane concentrati...

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“…The overlapping of the knowledge afferent to the hydrogeological and physicochemical fields in the geodatabase had the purpose to generate an integrated, solid, and digital CSM, able to conjoin multi-source data [32,33,47]. The geological-physical and hydrochemical modeling was performed through Rockworks 17 software [48]. The latter employs modeling algorithms to reconstruct an integrated three-dimensional subsurface model in a geographic information system (GIS) environment [28,29,31,34].…”

Section: The Multi-source and Geodatabase-driven Modeling Approachmentioning

confidence: 99%

Coupled Hydrogeochemical Approach and Sustainable Technologies for the Remediation of a Chlorinated Solvent Plume in an Urban Area

Ciampi

Esposito

Bartsch³

et al. 2022

Sustainability

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The presence of chlorinated solvents polluting groundwater in urbanized areas poses a significant environmental issue. This paper details a thoughtful approach to remediate a tetrachloroethylene (PCE) plume in a district that is characterized by a complex hydrological context with a limited accessibility. Through a geodatabase-driven and coupled hydrogeochemical approach, two distinct remediation technologies were chosen for the management of a contaminant plume. On one hand, coaxial groundwater circulation (CGC) wells coupled with air sparging (AS) aspire to promote the in-situ transfer of PCE from the contaminated matrices into a gaseous stream that is then treated above ground. On the other hand, reagent injection has the goal of enhancing chemical reduction combined with in situ adsorption, creating contaminant adsorbent zones, and stimulating dechlorinating biological activity. The development of an integrated conceptual site model (CSM) harmonizing geological, hydrochemical, and membrane interface probe (MIP) data captures site-specific hydrogeochemical peculiarities to support decision-making. The hydrochemical monitoring reveals contamination dynamics and decontamination mechanisms in response to treatment, quantifying the performance of the adopted strategies and investigating possible rebound effects. The estimation of masses extracted by the CGC-AS system validates the effectiveness of a new and sustainable technique to abate chlorinated solvents in groundwater.

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New insights into the hydrogeology and groundwater flow in the Great Barrier Reef catchment, Australia, revealed through 3D modelling

Cited by 9 publications

References 34 publications

Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Spatial Distribution of CO₂, CH₄, and N₂O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis

Coupled Hydrogeochemical Approach and Sustainable Technologies for the Remediation of a Chlorinated Solvent Plume in an Urban Area

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New insights into the hydrogeology and groundwater flow in the Great Barrier Reef catchment, Australia, revealed through 3D modelling

Cited by 9 publications

References 34 publications

Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef

Spatial Distribution of CO2, CH4, and N2O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis

Coupled Hydrogeochemical Approach and Sustainable Technologies for the Remediation of a Chlorinated Solvent Plume in an Urban Area

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Spatial Distribution of CO₂, CH₄, and N₂O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis