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Provenance of nutrients in submarine fresh groundwater discharge on Tahiti and Moorea, French Polynesia

Haßler, Kathrin and Dähnke, Kirstin and Kölling, Martin and Sichoix, Lydie and Nickl, Anna-Leah and Moosdorf, Nils (2019) Provenance of nutrients in submarine fresh groundwater discharge on Tahiti and Moorea, French Polynesia. Applied Geochemistry, 100, pp. 181-189. Elsevier. DOI: 10.1016/j.apgeochem.2018.11.020 ISSN 0883-2927

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Official URL: http://dx.doi.org/10.1016/j.apgeochem.2018.11.020

Abstract

Submarine fresh groundwater discharge (SFGD) provides a pathway for dissolved nutrients and other solutes from land to the ocean. It connects pollution from anthropogenic land use with coastal marine waters. In case of the oligotrophic central South Pacific Ocean around Tahiti and Moorea, French Polynesia, nutrient concentrations are particularly low. Both islands are surrounded by tropical coral reefs, which are highly sensitive to nutrient concentrations in the ambient water so that a surplus of nutrients, e.g. from SFGD, could lead to the degradation of coral reef ecosystems. We examined nutrient contributions from different land cover classes to nutrient fluxes through SFGD by combining nutrient concentration data, spatial data, oxygen and hydrogen isotope ratios of water (δ18OH2O and δ2HH2O, respectively) and nitrogen and oxygen isotope ratios of nitrate (δ15NNO3- and δ18ONO3-). Undeveloped land provides measurable quantities of phosphate while nitrate concentrations are often below the detection limit. The bulk of the nutrient load in nutrient enriched groundwater is of anthropogenic origin. It enters the aquifer system at low altitudes, where catchments are characterized by anthropogenic land use. Elevated nitrate concentrations are mainly associated with septic waste/manure inputs in fresh water. This study elucidates sources of nutrients in the groundwater of two volcanic islands, highlighting the impact that even a small populated area along the coast of an island can have, as well as the differences in nutrient transport between these seemingly similar locations.

Item URL in elib:https://elib.dlr.de/131403/
Document Type:Article
Title:Provenance of nutrients in submarine fresh groundwater discharge on Tahiti and Moorea, French Polynesia
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Haßler, KathrinZMT, BremenUNSPECIFIED
Dähnke, KirstinHelmholtz-Zentrum GeesthachtUNSPECIFIED
Kölling, MartinZentrum für Marine Umweltwissenschaften, Univ. BremenUNSPECIFIED
Sichoix, LydieUniv. of French Polynesia, Faaa, TahitiUNSPECIFIED
Nickl, Anna-LeahDLR, IPA und ZMT, BremenUNSPECIFIED
Moosdorf, NilsZMT, BremenUNSPECIFIED
Date:January 2019
Journal or Publication Title:Applied Geochemistry
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:100
DOI :10.1016/j.apgeochem.2018.11.020
Page Range:pp. 181-189
Publisher:Elsevier
ISSN:0883-2927
Status:Published
Keywords:Submarine groundwater discharge; Nutrients; French Polynesia; Tahiti; Moorea; Volcanic islands; Nitrogen and oxygen isotope ratios of nitrate
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:air traffic management and operations
DLR - Research area:Aeronautics
DLR - Program:L AO - Air Traffic Management and Operation
DLR - Research theme (Project):L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Nickl, Anna-Leah
Deposited On:27 Nov 2019 16:48
Last Modified:13 Mar 2020 11:09

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