Land inputs of trace metals, major elements, particulate organic carbon and suspended solids to an industrial coastal bay of NE Atlantic

Abstract

Rivers,streams and municipal and industrial effluents flowing into the Ferrol Ria (NW Spain) were analyzed for dissolved and particulate trace elements (Cd,Cu,Pb,Zn), particulate major elements (Al,Fe, Si),particulate organic carbon and nitrogen (POC and PON),and total suspended solids. Trace metal clean techniques were applied. Mean annual fluxes of these components were calculated. Dissolved trace metal concentrations in the major freshwater inputs were found to be within typical values for uncontaminated rivers: Cd: 0.020–0.035 nM; Cu: 11.7–19.2 nM; Pb: 0.40– 0.71nM and Zn: 18–54 nM. Two sources of suspended particulate matter (SPM) were observed: (i) a detrital SPM, which becomes more important at high river discharges,with metal concentrations tending to lithogenic values; (ii) an organic- and metal-rich SPM,which becomes dominant at low discharges. Municipal and industrial effluents in the northern shore,despite of constitute a minor freshwater contribution to the bay,were responsible for more than 50% of total inputs of Cu,Cd, Pb,Zn,POC and PON. The fluxes of trace metals obtained for the Ferrol Ria are in the range of other inhabited world semi-enclosed embayments.