Physico-chemical and environmental characterisation of sediments from Cantabrian estuaries (Northern Spain)

Abstract

Previous studies show that sediments of the Cantabrian estuaries (Northern Spain) contain significant concentrations of heavy metals and organic pollutants derived from intensive industrial, agricultural and urban activities. In the most polluted sediments of two estuaries (the bay of Santander and estuary of Suances), physico-chemical and environmental characterisation has been carried out. Water content, density, pH, specific surface, porosity and particle diameter distribution have been evaluated as physical parameters. Total metal contents have been analysed as inorganic parameters. Loss of ignition (LOI), phenol index and extractable organic halogens (EOX) have been determined as organic parameters. Two leachate assays have been carried out in order to evaluate the environmental behaviour of the sediments. Total availability has been analysed using the NEN 7341 test and the mobility of the pollutants has been determined using the EN 12457 leaching test at two liquid/solid ratios. The obtained results have been compared with European Union regulations. The physical parameters and inorganic compounds are very similar in the studied sediments. However, the sediments from Suances have high concentrations of LOI and EOX. The obtained correlation of the physical parameters with the particle size distribution is useful in the study of the sediment addition to ceramic process as a sediment management option. A comparison of the results obtained from the total, availability and mobility analysis of the inorganic pollutant concentrations of As, Ba, Ni, Pb and Zn present in sediments has been made, giving knowledge for the development of regulations and tools that would contribute to the integral management of the estuarine areas.