The Portuguese Index of Macroinvertebrates is used as a pollution index in the study of surface water in Portugal. From an environmental perspective, it is necessary to determine the pollution sources affecting surface water. Not only direct discharges of industrial and urban effluents are the cause; possibly the combination of other pollutions sources could result in ecological loss. To comprehend all the cause and effect relationships between pollution sources, water contamination and ecological integrity, it is necessary to apply complex models and possibly apply the use of thorough statistical tools. Structural Equation Modelling (SEM) has been used in the social sciences for a long time. Due to the present environmental concern and awareness of the phenomenon's complexity, SEM was used for environmental studies. In this paper are present SEM-PLS models that are applied to collected data from two different river basins, that of the Ave and the Sabor, in order to understand which are their main pollution sources and which contaminants are restraining biodiversity. The applied models from each basin reproduced different realities, as expected, since the river Ave has has the notorious impact of industry, while the Sabor basin has a higher level of water quality.
The bonds between pollution sources, contaminant concentrations and ecological damage are quite complex to access, but the proper management of river basins requires the full understanding of those interactions. In the present study, four SEM-PLS models were used to set up environmental cause-effect relationships in a heavily polluted urban catchment: the Ave River Basin. Data were collected within this watershed relative to point source discharges, diffuse emissions, diffuse indicators (e.g. land use), contaminant concentrations and a Portuguese index of macroinvertebrates diversity (IPtIN). The same dataset was used in the four SEM-PLS models, but each run was based on a different combination of latent variables. In all cases, it was possible to recognize that nitrogen discharges from livestock production, industrial and urban treatment plants are the dominant threats to water quality. The model results were robust, characterized by high, adjusted R Squared values-from 0.744 to 0.931. The models were also used to draw water quality maps. Now, the purpose was to test their prediction capability. Since more than 80% of the water courses were correctly classified for IPtIN, the predictions were considered feasible.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.