Talanta 70 (2006) 691–704 Identification and distribution of contamination sources in the Ebro river basin by chemometrics modelling coupled to geographical information systems Marta Terrado, Dami` a Barcel ´ o, Rom` a Tauler ∗ Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain Received 10 February 2006; received in revised form 3 May 2006; accepted 12 May 2006 Available online 7 July 2006 Abstract Identification of the main contamination sources of heavy metals, organic compounds and other physicochemical parameters in Ebro river surface waters and description of their temporal and spatial distributions, are analyzed using chemometrics and geostatistical methods. Historical data available from the Confederaci´ on Hidrogr´ afica del Ebro (CHE), which is the organization in charge of the management of the Ebro river basin; covering different years since 1992 for water, sediments and fish samples are investigated. Due to the great amount of data in these databases and to their complexity, chemometrics modelling (using principal components analysis, PCA) coupled to geographical information systems (GIS) is proposed to evaluate the environmental quality of the Ebro river basin. © 2006 Elsevier B.V. All rights reserved. Keywords: Ebro river; Contamination sources; Chemometrics; PCA; GIS 1. Introduction Diffuse and point pollution in the Ebro river basin (NE Spain) from agriculture, industry and human sewage, is an issue of great concern since together with changes in climatic conditions and land use practices have produced large scale adverse impacts on water quality and quantity. The Water Framework Directive 60/2000/CE and the Euro- pean Directive 76/464/CEE make compulsory the establishment of surveillance stations for the control of contamination in the aquatic environment (water, sediments and biota) by dangerous compounds in principal emission focus downstream. In waters, quality objectives have been fixed whereas in sediments and biota the main objective is to avoid a significant rise in time. The Confederaci´ on Hidrogr´ afica del Ebro (CHE) [1] has been controlling the concentration of some specific compounds in the whole basin with the establishment of a control network: the Red de Control de Sustancias Peligrosas (RCSP). ∗ Corresponding author. Tel.: +34 93 4006140; fax: +34 93 2045904. E-mail address: rtaqam@iiqab.csic.es (R. Tauler). Through the environmental monitoring program performed at different sampling sites and environmental compartments of the network, a large amount of concentration values of chemicals spread into the Ebro river basin are obtained. In order to derive useful environmental information from the data, the application of modern chemometric methods based in new multivariate fac- tor analysis [2] tools is proposed. The basic assumption of these methods when they are applied to environmental data tables is that each value of a measured variable in a particular sample is due to the sum of contributions from individual indepen- dent sources of different origin. Each one of these sources is characterized by a particular chemical composition profile and distributed among samples in a different way. As a result of the application of chemometric methods, main point and diffuse sources of contamination in the environment and their origin may be identified and their distribution profiles among samples (geographical, temporal, among environmental compartments) are characterized. Distribution of contamination sources and their impact over the territory can be assessed by the use of geo- graphical information systems [3,4] by means of cartographic techniques of symbols and pollution prediction maps. Geosta- tistical methods [5–7] based on mathematical and statistical functions are used, which allow the estimation of continuous 0039-9140/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2006.05.041