Wind-induced changes in the dynamics of fluorescent organic matter in the coastal NW Mediterranean

• Published in: The Science of the total environment 2017-12, Vol.609, p.1001-1012
• Main Authors: Aparicio, Fran L., Nieto-Cid, Mar, Calvo, Eva, Pelejero, Carles, López-Sanz, Àngel, Pascual, Josep, Salat, Jordi, Sánchez-Pérez, Elvia D., La Fuente, Patricia De, Gasol, Josep M., Marrasé, Cèlia
• Format: Article
• Language: English
• Subjects: DOC; FDOM; Inorganic nutrients; NW Mediterranean; Salinity; Wind events
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.07.170

Marine biogeochemistry dynamics in coastal marine areas is strongly influenced by episodic events such as rain, intense winds, river discharges and anthropogenic activities. We evaluated in this study the importance of these forcing events on modulating seasonal changes in the marine biogeochemistry of the northwestern coast of the Mediterranean Sea, based on data gathered from a fixed coastal sampling station in the area. A 4-year (2011–2014) monthly sampling at four depths (0.5m, 20m, 50m and 80m) was performed to examine the time variability of several oceanographic variables: seawater temperature, salinity, inorganic nutrient concentrations (NO3−, PO43− and SiO2), chlorophyll a (Chl a), dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM). FDOM dynamics was predominantly influenced by upwelling events and mixing processes, driven by strong and characteristic wind episodes. SW wind episodes favored the upwelling of deeper and denser waters into the shallower shelf, providing a surplus of autochthonous humic-like material and inorganic nutrients, whereas northerlies favored the homogenization of the whole shelf water column by cooling and evaporation. These different wind-induced processes (deep water intrusion or mixing), reported along the four sampled years, determined a high interannual environmental variability in comparison with other Mediterranean sampling sites. [Display omitted] •Four-year biogeochemical monitorization of a NW Mediterranean coastal station•Distinct strong winds cause homogenization of the water column or thermocline erosion.•FDOM dynamics was influenced by strong northerly and southerly winds.•EOS presented a high interannual variability that conditioned DOC dynamics.•Wind-induced effects can modify the proportion of the recalcitrant DOM in coastal waters.