Chemometric modeling of organic contaminant sources in surface waters of a mediterranean river basin.

Chemometric methods are applied to the analysis and interpretation of large multivariate datasets obtained in environmental monitoring studies. Concentrations of multiple organic compounds were measured in river samples taken from several sampling sites, at various geographical locations, during a number of campaigns and/or sampling time periods. Samples were collected and analyzed as part of an extensive multi-annual monitoring program from a mediterranean river basin (in Catalonia, at the northeast of Spain) by the Water Quality Regional Agency. Due to the great amount of multivariate data stored in environmental databases and to their complexity, chemometric modeling methods such as Principal Component Analysis (PCA) and Multivariate Curve Resolution with Alternating Least-Squares (MCR-ALS) coupled with appropriate mapping representations are proposed for the evaluation of the environmental quality of the studied rivers. Results achieved in this study are intended to be a contribution to water quality assessment and evaluation of contamination of surface waters in river basins, and to support public policies of environmental control and management of the regions under study.

Combined use of Daphnia magna in situ bioassays, biomarkers and biological indices to diagnose and identify environmental pressures on invertebrate communities in two Mediterranean urbanized and industrialized rivers (NE Spain).

Environmental factors affecting aquatic invertebrate communities were assessed using Daphnia magna in situ bioassays and biological indices based on community assemblages of benthic macroinvertebrates. Investigations were carried out in two heavily industrialized and urbanized river basins from the NE of Spain (Llobregat and Besós). Measures of energy consumption (i.e. algal grazing), and of specific biochemical responses (biomarkers) were conducted on individuals transplanted upstream and downstream from effluent discharges of sewage treatment plants. In both rivers there was a clear deterioration of the ecological water quality parameters and benthic communities towards downstream reaches. In all but one of the 19 locations studied, transplanted organisms were affected in at least one of the five measured responses. In three of them, significant effects were detected in most of the traits considered. Principal Component and Partial Least Square Projections to Latent Structures regression analyses indicated that the measured responses in D. magna in situ bioassays and those of macroinvertebrate assemblages were affected by distinct environmental factors. From up to 20 environmental variables considered, seven of them including habitat degradation, suspended solids, nitrogenous and conductivity related parameters affected macroinvertebrate assemblages. On the other hand, levels of organophosphorus compounds and polycyclic aromatic hydrocarbons were high enough to trigger the responses of D. magna in situ bioassays. These results emphasize the importance of combining biological indices with biomarkers and more generalized and ecologically relevant (grazing) in situ responses to identify ecological effects of effluent discharges from sewage treatment plants in surface waters.