Fluvial contributions of nutrient salts, dissolved trace elements and organic carbon to the sea by pristine temperate rivers (SW Europe)

Abstract

Environmental context We report the baseline levels of dissolved nutrients, organic matter and metals in the main temperate rivers draining the three Northern Galicia rias. Because the rivers are pristine, these rias are little affected by anthropogenic inputs, and their properties reflect the lithological characteristics of the rivers’ watersheds. Useful information in the development of European and global initiatives for assessing anthropogenic inputs to estuarine, coastal and open-sea environments has been provided. Abstract A summary of the water characteristics of the rivers Sor, Mera and Landro that drain into the Northern Galician Rias (NW Iberian Peninsula) is presented. The analysis was based on fortnightly monitoring during 2008, for major and minor chemical elements in the dissolved phase (Al, As, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, U, V, Zn), nutrients (nitrate, nitrite, ammonium, phosphate, silicate), suspended particulate matter, chlorophyll-a and tracers of water quality chemistry (dissolved inorganic nitrogen and carbon). The data cover rivers not urban, agriculturally or industrially affected. Continental inputs of the material via rivers into the Northern Galician Rias were measured and annual fluxes of the dissolved chemical elements to the rias were calculated. In spite of the high variability in water flow, this study provides a good estimate of the overall amounts of nutrients and dissolved elements discharged to pristine ria systems.