Reconstructing past anthropogenic impact on Italian Dark Earths by means of a multi-analytical approach

Abstract

Dark Earths (DE) are soil deposits resulting from past settlements and human activities on natural soils. Those soils are referred to as cultural layers as they embed several clues of past domestic habits. The first DE were discovered in Amazonia, and by the 1970s, DE layers were excavated under European towns. Since the first studies, scholars focused on the remarkable abundance of black particles present in the soil matrix. Indeed, the origin of these charred particles and the properties derived from them (i.e., the strong fertility power) have been studied by chemists, soil scientists, and archeologists, highlighting the complexity of the DE formation. In this thesis, DE from Verona were characterized starting from the microscopic level of the layers up to the chemical and physical properties of the inclusions. The samples were radiocarbon dated and referred to the Medieval and Bronze Age. The soil morphology of the deposits was described, whereas PAHs and Raman parameters of the charred particles permitted us to classify the type of fire event and to identify the type of biomasses burned. The typology of vegetation and the level of microbic manipulation of the organic matter in soil were defined with the use of n-alkanes and miliacin. Fecal input in DE was assessed through classification models starting from a database of the fecal sterols in feces from humans and animals. The results permitted to outline that various domestic activities were involved in the formation of these layers, and being strictly anthropogenic, differences were evidenced even in a short-scale distance; indeed, the human impact was mainly related to soil exploitation for agricultural and livestock activities.