title: Urbanization impact on sulfur content of groundwater revealed by the study of urban speleothem-like deposits: Case study in Paris, France.
abstract: Speleothem-like deposits that develop underground in urban areas are an archive of the environmental impact of anthropic activities that has been little studied so far. In this paper, the sulfate content in shallow groundwater from northern Paris (France) is compared with the sulfur content in two 300-year-old urban carbonate deposits that grew in a historical underground aqueduct. The present-day waters of the aqueduct have very high sulfur and calcium contents, suggesting pollution from gypsum dissolution. However, geological gypsum levels are located below the water table. Sulfur content was measured by micro-X-ray fluorescence in these very S-rich carbonate deposits (0.5 to 1% of S). A twofold S increase during the second half of the 1800s was found in both samples. These dates correspond to two major periods of urbanization above the site. We discus three possible S sources: anthropic sources (industries, fertilizers…), volcanic eruptions and input within the water through gypsum brought for urbanization above the studied site (backfill with quarry waste) since the middle of the 19th century. For the younger second half of the studied section, S input from gypsum brought during urbanization was confirmed by the study of isotopic sulfur composition (δ34S=+15.2‰ at the top). For the oldest part, several sulfur peaks could be related to early industrial activity in Paris, that caused high local air pollution, as reported in historical archives but also to historical gypsum extraction. This study provides information on the origin and timing of the very high SO42-levels measured nowadays within the shallow groundwater, thus demonstrating the interest in using carbonate deposits in urban areas as a proxy for the history of urbanization or human activities and their impact on water bodies.
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France. Electronic address: edwige.pons-branchu@lsce.ipsl.fr.
authors.forename: E
authors.initials: E
authors.lastname: Pons-Branchu
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
authors.forename: M
authors.initials: M
authors.lastname: Roy-Barman
authors.affiliation: LUNAM Université, IFSTTAR - centre de Nantes, Route de Bouaye CS4, 44344 Bouguenais, France.
authors.forename: L
authors.initials: L
authors.lastname: Jean-Soro
authors.affiliation: CNAM: HT2S, EA 3716, 2 rue Conté, 75003 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Guillerme
authors.affiliation: CEREMA, 12 Rue Teisserenc de Bort, 78197 Trappes-en-Yvelines Cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Branchu
authors.affiliation: CNAM: HT2S, EA 3716, 2 rue Conté, 75003 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Fernandez
authors.affiliation: CEREMA Rue de l'Egalité Prolongée - BP 134, 93352 Le Bourget Cedex 319, France.
authors.forename: E
authors.initials: E
authors.lastname: Dumont
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
authors.forename: E
authors.initials: E
authors.lastname: Douville
authors.affiliation: GEOPS Univ. Paris-Sud, CNRS, Université Paris-Saclay, Bâtiment 504, Rue du Belvédère, 91405 Orsay Cedex, France.
authors.forename: J L
authors.initials: JL
authors.lastname: Michelot
authors.affiliation: GNS Science, National Isotope Centre, Lower Hutt, New Zealand.
authors.forename: A M
authors.initials: AM
authors.lastname: Phillips
mesh_terms: D004784:Environmental Monitoring; D005602:France; D060587:Groundwater / Q000737:chemistry*; D010297:Paris; D013455:Sulfur / Q000032:analysis*; D014507:Urbanization; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D013455:Sulfur
keywords: Aqueduct; Groundwater; Speleothems; Sulfur; Urbanization; δ(34)S