The connection between Submarine Groundwater Discharge and seawater quality: The threat of treated wastewater injected into coastal aquifers.

Autor: Alorda-Kleinglass A; Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain; Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain. Electronic address: aaron.alorda@uab.cat., Rodellas V; Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain. Electronic address: valenti.rodellas@uab.cat., Diego-Feliu M; Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain., Marbà N; Global Change Research Group, Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), 07190 Esporles, Mallorca, Spain., Morell C; Global Change Research Group, Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), 07190 Esporles, Mallorca, Spain., Garcia-Orellana J; Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain; Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Catalonia, Spain.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Apr 20; Vol. 922, pp. 170940. Date of Electronic Publication: 2024 Feb 14.
DOI: 10.1016/j.scitotenv.2024.170940
Abstrakt: Submarine Groundwater Discharge (SGD) delivers nutrients to the coastal sea triggering phytoplankton blooms, eutrophication, and can also serve as a pathway for contaminants. Wastewater treatment plants (WWTP) including injection wells in coastal areas influence coastal aquifers and might impact the composition and magnitude of SGD fluxes. In tourist areas, wastewater treatment may be less efficient and larger in volume during high seasons, potentially impacting nutrient fluxes from SGD and exacerbating environmental impacts. This study analyzes the nutrient transfer from treated wastewater injection in karstic aquifers to the coastal sea via SGD, considering the impacts of tourism seasonality. This study is conducted in Cala Deià, a small cove in the Balearic Islands, a Mediterranean tourist destination. The findings suggest that the seasonality of tourism, leading to variations in the volume of wastewater treated in the WWTP, influences the dynamics of the coastal aquifer. This leads to increased SGD water and nutrient fluxes to the sea in summer, i.e. the peak tourist season. The measured DIN, DIP, and DSi inventories in the cove are much larger in August than in April (3, 10, and 1.5 times higher, respectively) due to higher input of nutrients in summer due to SGD impacted by the WWTP. These elevated nutrient flows can support algal blooms in the cove, compromising water quality for local swimmers and tourists. Indeed, in August, shoreline stations exhibited eutrophic Chl-a concentrations, with peaks reaching approximately 4 mg Chl-a L -1 . These elevated levels suggest the presence of an algal bloom during the survey. The anthropogenic origin of SGD-driven nutrients is traced in seawater and seagrass meadows, as evidenced by high ∂ 15 N signatures indicative of polluted areas. Thus, the high pressure exerted on coastal areas by tourism activities increased the magnitude of SGD nutrient fluxes, thereby threatening coastal ecosystems and the services they provide.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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