The distribution of Pb, Cu and Zn in topsoil of the Campanian region, Italy

In this paper we present a comparison of statistical and spatial distributions between Pb, Cu and Zn concentration data and clr-transformed data of 3669 topsoil samples from the Campanian Region. Results show that both approaches, the classical univariate analysis and the compositional data analysis, are necessary to understand the real structure of the data and shed light on different aspects. In particular, the spatial distributions of concentration (‘raw’) data and clr-transformed data of the three elements differ completely. Raw data essentially represent a high anthropogenic impact, requiring an additional human health risk assessment for the three investigated elements. The information obtained by the clr-coefficient maps reveals the geogenic contribution to the element distribution. To better constrain the degree of contamination due to these potentially toxic elements and their impact on human health, we present an RGB composite map of Pb, Cu and Zn. This map unravels potential sources of contamination and locates the areas where concentrations exceed thresholds established by the Italian legislation.