Assessing pollution trends in the Guadalquivir River estuary using N-way analysis

Human activities have contributed to a deployment of environmental quality. In the last decades the problem of water preservation has gained increasing attention, and new policies have been developed for water resources remediation. Statistical techniques for data treatment are based on the organization of data in a bi-dimensional array; thus, some shades on the trend of the distribution tend to be ignored. Multiway techniques, where data are gathered in n directions, allow the analysis of the results through different directions at the same time. In particular, for 3MPCA a principal components analysis is conducted using three modes and a “core” matrix that allows assessing their interactions. The Guadalquivir River estuary has been used as a model system for the application of 3MPCA in the study of long term evolution of pollutants. Nutrients and heavy metals ultra-traces level have been used to characterize the estuary. The 3MPCA was used to assess the relationships within chemical variables, sampling stations and sampling campaigns.