Assessing arsenic sources in landfill areas: a case study in Sardinia

Concentrations of dissolved As can be related either to natural processes or anthropogenic activities. The aim of this study was to distinguish natural processes from potential anthropogenic effects on As occurrence in landfill areas. The study area is located in Central Sardinia and is characterized by Upper Pleistocene and Holocene sediments (sand and gravel with silt-clay matrix and local occurrence of thin ochreous colour levels; marsh deposits rich in organic matter and vegetal residues). The study area hosts an exhausted landfill where construction and demolition debris were disposed. The mineralogical composition of solid materials was characterized by quartz, feldspars and clay minerals. Concentrations of As were within the ranges reported in sediments and soils, except one sample that showed 46 mg/kg As. The waters showed near-neutral pH, variable electric conductivity (