Monitoring procedures in environmental geochemistry and compositional data analysis theory

First discussion on compositional data analysis is attributable to Karl Pearson, in 1897. However, notwithstanding the recent developments on algebraic structure of the simplex, more than twenty years after Aitchison’s idea of log-transformations of closed data, scientific literature is again full of statistical treatments of this type of data by using traditional methodologies. This is particularly true in environmental geochemistry where besides the problem of the closure, the spatial structure (dependence) of the data have to be considered. In this work we propose the use of log-contrast values, obtained by asimplicial principal component analysis, as LQGLFDWRUV of given environmental conditions. The investigation of the log-constrast frequency distributions allows pointing out the statistical laws able togenerate the values and to govern their variability. The changes, if compared, for example, with the mean values of the random variables assumed as models, or other reference parameters, allow definingmonitors to be used to assess the extent of possible environmental contamination. Case study on running and ground waters from Chiavenna Valley (Northern Italy) by using Na+, K+, Ca2+, Mg2+, HCO3-, SO4 2- and Cl- concentrations will be illustrated

Arqueología de paisajes altimontanos pirenaicos: formas de explotación y usos del medio en época romana en valle del Madriu-Perafita-Claror (Andorra) y en la Sierra del Cadí (Alt Urgell)

long-term cultural history of the Madriu-Perafita-Claror valleys (Andorra) and the Cadí Range (Catalonia) has been investigated thanks to the combination of archaeological surveys and excavation, analysis of written sources, multiproxy alaeoenvironment analysis (pollen, NPP, micro and macro charcoal, sedimentology and geochemistry), and digital technologies such as stereophotogrammetry, multispectral imaging, DGPS and GIS. The project has been designed from a landscape archaeology approach and the study area has been selected due to the suitable setting it provides for a meaningful application of the aforementioned techniques. Consequently, archaeological, historical and palaeoenvironmental data have been all treated as cultural proxies. Their comparison has allowed obtaining not only coherent but also complementary results. The project outcomes show an uninterrupted occupation of these high mountain valleys (2000-2600 m a.s.l.) from the Mesolithic until the present. This human occupation shows strong spatial and chronological variability in human practices ranging from a stable long term group occupation in the Late Neolithic to the diversification of representative practices during the Roman period (metallurgy, pine resin exploitation, charcoal production, pastoralism, etc.). This high diversity of activities leads to complex cultural landscapes in the high Pyrenean areas. The reconstruction of the cultural history at the study areas will allow the development of more sustainable politics for these landscapes management.