title: Bromine enrichment in marsh sediments as a marker of environmental changes driven by Grand Solar Minima and anthropogenic activity (Caminha, NW of Portugal).
abstract: A sediment core collected in Caminha tidal marsh, NW Portugal, was used to assess bromine (Br) signal over the last ca. 1,700 years. The Br temporal variability reflects its close relationship with soil/sediment organic matter (OM) and also alterations in Br biogeochemical recycling in marsh environment. The highest Br enrichment in sediments was found during the Maunder Solar Minimum, a major solar event characterized by lower irradiance (TSI) and temperature, increased cloudiness and albedo. The obtained results suggest that those climate-induced changes weakened the natural mechanisms that promote Br biochemical transformations, driven by both living plants metabolism and plant litter degradation, with the ensuing generation of volatile methyl bromide (CH3Br). It seems that the prevailing climate conditions during the Maunder favoured the retention of more Br in marsh ecosystem, ultimately decreasing the biogenic Br emissions to the atmosphere. During the 20th century, the Br pattern in sediments appears to mirror likewise anthropogenic sources. The significant correlation (p<0.05) between Br/OM ratios and Pb contents in sediments after 1934 suggests a common source. This is most probably related with the rise, massive consumption and prohibition of leaded gasoline, where ethylene dibromide was added as lead scavenger to antiknock mixtures. More regionally, the concerted use of flame retardants on forest fire management, covering the 1980s through mid-1990s in the north of Portugal and Galicia, could be responsible for the observed increase of sediment Br (relatively to Pb) pool of this tidal marsh. Although man-made brominated compounds are being phased-out since the inception of the 1992 Montreal Protocol, the Caminha tidal marsh sedimentary record showed that Br levels only started to decline after 2002.
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Centro e Departamento de Geologia, Campo Grande, 1749-016 Lisboa, Portugal. Electronic address: jcmoreno@fc.ul.pt.
authors.forename: J
authors.initials: J
authors.lastname: Moreno
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Centro e Departamento de Geologia, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Fatela
authors.affiliation: East Carolina University, Department of Geological Sciences, Greenville, NC 27858-4353, USA.
authors.forename: E
authors.initials: E
authors.lastname: Leorri
authors.affiliation: Universidade de Lisboa, Instituto Superior Técnico, Centro de Ciências e Tecnologias Nucleares, Estrada Nacional 10, km 139,7, 2695-066 Bobadela LRS, Portugal.
authors.forename: M F
authors.initials: MF
authors.lastname: Araújo
authors.affiliation: Universidade de Lisboa, Instituto Superior Técnico, Centro de Ciências e Tecnologias Nucleares, Estrada Nacional 10, km 139,7, 2695-066 Bobadela LRS, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Moreno
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Sevilla, Av. Reina Mercedes 10, 41012 Sevilla, Spain.
authors.forename: J
authors.initials: J
authors.lastname: De la Rosa
authors.affiliation: Universidade de Lisboa, Faculdade de Ciências, Centro e Departamento de Geologia, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: M C
authors.initials: MC
authors.lastname: Freitas
authors.affiliation: Universidade do Minho, Centro de Investigação Geológica, Ordenamento e Valorização de Recursos (CIG-R), Departamento de Ciências da Terra, CIG-R, 4710-057 Braga, Portugal.
authors.forename: T
authors.initials: T
authors.lastname: Valente
authors.affiliation: East Carolina University, Department of Geological Sciences, Greenville, NC 27858-4353, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Corbett
mesh_terms: D001966:Bromine / Q000032:analysis*; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D011174:Portugal; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D001966:Bromine
keywords: Anthropogenic impacts; Biogenic CH(3)Br emissions; Bromine; NW Iberia; Solar activity; Tidal marsh