Evaluation of changes in spatial pattern of metals pollution in surface water using multivariate analysis: case study an urban basin from Buenos Aires, Argentina

Temporal changes in metal concentrations in a polluted urban basin: the contribution of multivariate techniques to the evaluation of their recovery

“…Two possible scenarios could be considered for these sites: having no chance of recovery or that the actions of ACUMAR are not always effective or are not carried out in a sustained manner. It is probable that ACUMAR has concentrated its actions, such as industrial reconversion plans and relocation of settlements, in the lower basin due to its high levels of pollution and the large number of marginal urban settlements located on the Riachuelo coast (Tripodi et al 2021). On the other hand, the results of this study also showed that temporary trends had variations, seasonal or episodic events, in metal concentrations.…”

“…However, to quantify recovery success, the use of these analyses could make di cult to determine which are the pollutants that describe the changes over time and the factors associated. The multivariate techniques are appropriate for this purpose as they allow simultaneous evaluation of all variables in a complex dataset (Haase and Ellis 1987;Tripodi et al 2021). Among them, the Asymmetric Eigenvectors Maps (AEM) analysis is a multivariate technique that was originally developed to model multivariate spatial distributions generated by a directional physical process and had usually been applied to study communities of living organisms (Legendre and Gauthier 2014).…”

“…Among them, the Asymmetric Eigenvectors Maps (AEM) analysis is a multivariate technique that was originally developed to model multivariate spatial distributions generated by a directional physical process and had usually been applied to study communities of living organisms (Legendre and Gauthier 2014). This analysis along with the redundancy analysis (RDA) are two multivariate techniques that have been useful for determining spatial patterns in metal contamination (Tripodi et al 2021). As the processes associated with time are directional, these two techniques should also be suitable for analyzing time series of pollutants (Legendre and Gauthier One of the main pollutants of this basin are metals, showing concentrations of zinc, lead, copper, nickel and chromium in sediment samples from the Riachuelo River above the recommended levels for the protection of aquatic life (Rendina and de Iorio 2012; Ronco et al 2008).…”

“…These types of industries were responsible for 50% of the pollutants present in the water of Riachuelo (Casares and de Cabo 2018; Nápoli 2009). In this way, site 5, which is located in the area with the highest number of leather tanning industries in the basin(Tripodi et al 2021), showed high levels of chromium, BOD, COD and TSS.…”