Latent Compositional Factors in The Llobregat River Basin (Spain) Hydrogeochemistry

Authors: Tolosana-Delgado, R.¹; Otero, N.²; Pawlowsky-Glahn, V.³; Soler, A.⁴

Source: Mathematical Geology, Volume 37, Number 7, October 2005 , pp. 681-702(22)

Publisher: Springer

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Abstract:

The study of hydrogeochemical data sets frequently calls for statistical dimension reducing techniques. It is well known that hydrochemical parameters are compositions and, for this type of data, the direct application of classical statistical methods based on the correlation matrix yield spurious results. But new results on compositional data analysis have identified the sampling space, the simplex, with an Euclidean space, a fact that allows us to define a simplicial factor analysis strategy, thus overcoming the problem. For illustration, we use samples from the Llobregat River and its tributaries (NE Spain). Three unobservable or latent factorial components are extracted, which are identified with pristine waters, potash-mining influence and urban sewage influence. These three factorial components or compositional factors are plotted in a factorial ternary diagram, which reflects the relative influence of each one of these factors on each observation.

Keywords: biplot; isometric log-ratio coordinates; end-member; orthonormal basis; river pollution

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s11004-005-7375-7

Affiliations: 1: Email: raimon.tolosana@udg.es 2: Email: notero@ub.edu 3: Email: vera.pawlowsky@udg.es 4: Email: albertsolergil@ub.edu

Publication date: 2005-10-01