title: Spatial and seasonal variability of CH4in the eastern Gulf of Cadiz (SW Iberian Peninsula).
abstract: Methane (CH4) concentrations were measured along three sections of the eastern Gulf of Cadiz (designated "Guadalquivir", "Sancti Petri" and "Trafalgar") during eight cruises in 2014 and 2015. The concentration of CH4varied from 3.6 to 19.7nmolkg-1(CH4saturation percent of 122 and 916%), showing seasonal variation. The highest values were found in December 2014 and November 2015. In most of the sampling area the highest concentration of CH4was found in subsurface waters at depths close to the thermocline, and in the bottom waters near the coast. The seawater-air flux of CH4ranged between 0.8 and 59.7μmolm-2d-1, showing seasonal variation in function of the temperature of the surface water. In the "Guadalquivir" and "Sancti Petri" sections, the CH4fluxes increased with proximity to the coast; this may be a result of continental inputs and CH4emissions from sediments. The whole study area behaves as a source of CH4to the atmosphere with mean values of 0.5 and 0.6GgCH4yr-1in 2014 and 2015, respectively.
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain. Electronic address: ana.sierra@uca.es.
authors.forename: A
authors.initials: A
authors.lastname: Sierra
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Jiménez-López
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain.
authors.forename: T
authors.initials: T
authors.lastname: Ortega
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Ponce
authors.affiliation: Instituto Español de Oceanografía, Centro Oceanográfico de Cádiz, Puerto Pesquero, Muelle de Levante s/n, Apdo. 2609, E-11006 Cádiz, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bellanco
authors.affiliation: Instituto Español de Oceanografía, Centro Oceanográfico de Cádiz, Puerto Pesquero, Muelle de Levante s/n, Apdo. 2609, E-11006 Cádiz, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Sánchez-Leal
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Gómez-Parra
authors.affiliation: Dpto. Química-Física, INMAR, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Campus Universitario Río San Pedro, 11510 - Puerto Real, Cádiz, Andalucía, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Forja
keywords: Continental shelf; Gulf of Cadiz; Methane; Seawater-air fluxes