Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition
In coastal aquifers, two opposite but complementary processes occur: Seawater intrusion (SWI), which may salinize heavily exploited aquifers, and Submarine groundwater discharge (SGD) which transports oligo-elements to the sea. Aquifers are expected to be chemically reactive, both because they provide abundant surfaces to catalyze reactions and the mixing of very different Fresh Water (FW) and Sea Water (SW) promote numerous reactions. Characterizing and quantifying these reactions is essential to assess the quality and composition of both aquifer water, and SGD. Indeed, sampling SGD is difficult, so its composition is usually uncertain. We propose a reactive end-member mixing analysis (rEMMA) methodology based on principal component analysis (PCA) to (i) identify the sources of water and possible reactions occurring in the aquifer and (ii) quantify mixing ratios and the extent of chemical reactions. We applied rEMMA to the Argentona coastal aquifer located North of Barcelona that contains fluvial sediments of granitic origin and overlies weathered granite. The identification of end members (FW and SW) and the spatial distribution of their mixing ratios illustrate the application procedure. The extent of reactions and their spatial distribution allow us to distinguish reactions that occur as a result of mixing from those caused by sediment disequilibrium, which are relevant to recirculated saltwater SGD. The most important reaction is cation exchange, especially between Ca and Na, which promotes other reactions such as Gypsum and Fluorite precipitation. Iron and Manganese are mobilized in the SW portion but oxidized and precipitated in the mixing zone, so that Fe (up to 15 μEq/L) and Mn (up to 10 μEq/L) discharge is restricted to SW SGD. Nitrate is reduced in the mixing zone. The actual reaction amounts are site-specific, but the processes are not, which leads us to conjecture the importance of these reactions to understand the SGD discharge elsewhere.
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Language: | English |
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Elsevier
2022-09-10
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Subjects: | Submarine groundwater discharge, Chemical reactions, Coastal aquifers, EMMA analysis, Groundwater, Mixing model, |
Online Access: | http://hdl.handle.net/10261/273247 http://dx.doi.org/10.13039/501100004837 https://api.elsevier.com/content/abstract/scopus_id/85130913169 |
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dig-idaea-es-10261-2732472024-05-15T20:39:22Z Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition Goyetche, Tybaud Luquot, Linda Carrera, Jesús Martínez-Pérez, Laura Folch, Albert Ministerio de Ciencia e Innovación (España) Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model In coastal aquifers, two opposite but complementary processes occur: Seawater intrusion (SWI), which may salinize heavily exploited aquifers, and Submarine groundwater discharge (SGD) which transports oligo-elements to the sea. Aquifers are expected to be chemically reactive, both because they provide abundant surfaces to catalyze reactions and the mixing of very different Fresh Water (FW) and Sea Water (SW) promote numerous reactions. Characterizing and quantifying these reactions is essential to assess the quality and composition of both aquifer water, and SGD. Indeed, sampling SGD is difficult, so its composition is usually uncertain. We propose a reactive end-member mixing analysis (rEMMA) methodology based on principal component analysis (PCA) to (i) identify the sources of water and possible reactions occurring in the aquifer and (ii) quantify mixing ratios and the extent of chemical reactions. We applied rEMMA to the Argentona coastal aquifer located North of Barcelona that contains fluvial sediments of granitic origin and overlies weathered granite. The identification of end members (FW and SW) and the spatial distribution of their mixing ratios illustrate the application procedure. The extent of reactions and their spatial distribution allow us to distinguish reactions that occur as a result of mixing from those caused by sediment disequilibrium, which are relevant to recirculated saltwater SGD. The most important reaction is cation exchange, especially between Ca and Na, which promotes other reactions such as Gypsum and Fluorite precipitation. Iron and Manganese are mobilized in the SW portion but oxidized and precipitated in the mixing zone, so that Fe (up to 15 μEq/L) and Mn (up to 10 μEq/L) discharge is restricted to SW SGD. Nitrate is reduced in the mixing zone. The actual reaction amounts are site-specific, but the processes are not, which leads us to conjecture the importance of these reactions to understand the SGD discharge elsewhere. This work has been funded by the Spanish Government through MEDISTRAES III projects (grant nos. PID2019-110212RB-C22 and PID2019-110311RB-C21), LOGIC project (grant no. RTC2019-007484-5) and IDAEA-CSIC Center of Excellence Severo Ochoa (Grant CEX2018-000794-S). This work is also part of the project TerraMar (grant no. ACA210/18/00007) of the Catalan Water Agency. We also acknowledge the Spanish Ministry of Economy, Industry and Competitiveness for the PhD fellowship (BES-2017-080028) from the FPI Program awarded to T. Goyetche. The author A. Folch is a Serra Húnter Fellow. Peer reviewed 2022-06-27T07:21:25Z 2022-06-27T07:21:25Z 2022-09-10 artículo http://purl.org/coar/resource_type/c_6501 Science of the Total Environment 838 Part 1: 155978 (2022) 00489697 http://hdl.handle.net/10261/273247 10.1016/j.scitotenv.2022.155978 http://dx.doi.org/10.13039/501100004837 35588800 2-s2.0-85130913169 https://api.elsevier.com/content/abstract/scopus_id/85130913169 en #PLACEHOLDER_PARENT_METADATA_VALUE# info:eu-repo/grantAgreement/AEI/MCIN/CEX2018-000794-S The Science of the total environment Postprint Sí embargo_20240910 Elsevier |
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Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model |
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Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model Goyetche, Tybaud Luquot, Linda Carrera, Jesús Martínez-Pérez, Laura Folch, Albert Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
description |
In coastal aquifers, two opposite but complementary processes occur: Seawater intrusion (SWI), which may salinize heavily exploited aquifers, and Submarine groundwater discharge (SGD) which transports oligo-elements to the sea. Aquifers are expected to be chemically reactive, both because they provide abundant surfaces to catalyze reactions and the mixing of very different Fresh Water (FW) and Sea Water (SW) promote numerous reactions. Characterizing and quantifying these reactions is essential to assess the quality and composition of both aquifer water, and SGD. Indeed, sampling SGD is difficult, so its composition is usually uncertain. We propose a reactive end-member mixing analysis (rEMMA) methodology based on principal component analysis (PCA) to (i) identify the sources of water and possible reactions occurring in the aquifer and (ii) quantify mixing ratios and the extent of chemical reactions. We applied rEMMA to the Argentona coastal aquifer located North of Barcelona that contains fluvial sediments of granitic origin and overlies weathered granite. The identification of end members (FW and SW) and the spatial distribution of their mixing ratios illustrate the application procedure. The extent of reactions and their spatial distribution allow us to distinguish reactions that occur as a result of mixing from those caused by sediment disequilibrium, which are relevant to recirculated saltwater SGD. The most important reaction is cation exchange, especially between Ca and Na, which promotes other reactions such as Gypsum and Fluorite precipitation. Iron and Manganese are mobilized in the SW portion but oxidized and precipitated in the mixing zone, so that Fe (up to 15 μEq/L) and Mn (up to 10 μEq/L) discharge is restricted to SW SGD. Nitrate is reduced in the mixing zone. The actual reaction amounts are site-specific, but the processes are not, which leads us to conjecture the importance of these reactions to understand the SGD discharge elsewhere. |
author2 |
Ministerio de Ciencia e Innovación (España) |
author_facet |
Ministerio de Ciencia e Innovación (España) Goyetche, Tybaud Luquot, Linda Carrera, Jesús Martínez-Pérez, Laura Folch, Albert |
format |
artículo |
topic_facet |
Submarine groundwater discharge Chemical reactions Coastal aquifers EMMA analysis Groundwater Mixing model |
author |
Goyetche, Tybaud Luquot, Linda Carrera, Jesús Martínez-Pérez, Laura Folch, Albert |
author_sort |
Goyetche, Tybaud |
title |
Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
title_short |
Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
title_full |
Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
title_fullStr |
Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
title_full_unstemmed |
Identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
title_sort |
identification and quantification of chemical reactions in a coastal aquifer to assess submarine groundwater discharge composition |
publisher |
Elsevier |
publishDate |
2022-09-10 |
url |
http://hdl.handle.net/10261/273247 http://dx.doi.org/10.13039/501100004837 https://api.elsevier.com/content/abstract/scopus_id/85130913169 |
work_keys_str_mv |
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