lncidence and distribution of heavy metals in sediments of the Turia River basin

Póster presentado en el congreso 4th SCARCE International Conference, celebrado en Cádiz, España el 25 y 26 de noviembre de 2013Rivers are one of the mainsources of freshwater to population but, in the same way, receive both point source and difuse pollution, usually frorm wastewaters and agriculture. However, rivers are not independent bodies but they influence different associated ecosystems that compound the catchment. In this sense the fluvial sedimentary phase can act as a sink of pollutants Sediments can act as resevoirs that accumulate contaminants fixing them or allowing their decomposition or metabolization. However, environmental changes oor h uman induced ones, shuch as variations in water pH, increases in the turbulence or intensity of the water flow, etc.could favour their release to the environment. In this work, the i ncidence and distribution of seven heavy metals was monitored in the sediments of the Turia River. Along the river course, 22 zones were selected for sampling according different lithologies, land uses, size of popu1ations and the proxirnity to waste waters treatment plants (WWTPs), from the headwaters to the mouth. The selected metals (Cd, Co, Cr, Cu, Pb, Ni and Zn) were analysed to determine its total and extractable contents in the sediments. Total content of metals was extracted by microwave acid digestion and the extractable fraction by treatment with EDTA. Atomic Absorption Spectrometry, using graphite furnace when necessary, was used for the determination of all metals. Highest values were mainly observed in zones 10 and 22, close to urban areas, reaching values of 172.86 mg/kg for Pb, or 58.34 mg/kg for Cr. However, zone 2 near in the headwaters of the Alfambra River and supposedly of reference for the River authorities shows the highest values of zinc with 96.96 mg/kg . Regarding the available/extractable fraction of the metals, Cd, Co and Cr were under the detection 1imitswith maximum values in zone 22 too, reching in the case of Pb 59.60 mg/kg. The percentage of available metal in the sediments of the studied zones vary between 15 and 40% for Cu, Pb and Zn, bei ng the higher than 60% for Pb and Zn in zone 8 near the city of Teruel. The organic matter content of the sediments is the parameter most strongly related with all the forms of metals, mainly for Cu, Ni, Pb and Zn, and is a key factor in the availability of them. [t has to be noted that the textural distribution of the sediments, particularly the clay content, also influences this last factor in the case of Ni. A strong tendency towards enrichment of the sediments in heavy metals is observed in the Turia River from North to South, from the headwater to the stuary, with the exception of the possible existence of a contamination source in zone 2.This work has been supported by the Spanish Ministry of Science and Innovation and the European Regional Development Funds (ERDF) through the coordinating project MEFTURIA (CGL2011-29703-0O2-00), and its subprojects EFAMED and EMEFOR (CGL2011-29703-0O2-02), and the project CONSOLIDER-INGENIO 2010 (CSD2009).Peer Reviewe