Environmental mobility of potentially toxic trace elements of Andean volcanic ashes

This research investigate the geochemical environmental impact of ancient ash deposits erupted to hundreds of thousands to several million years ago in the southern Puna and neighbouring areas (Argentina), Uruguay and five historical eruptions occurred over a 20-year period in the Andes. In the latter case, pristine ash samples of Cophue, 2000, Lonquimay, 1988, Llaima, 2008, Chaiten, 2008, and Hudson, 1999 eruptions were studied. The main purpose of this research is to investigate the geochemical environmental hazard posed by different types of volcanic ashes in general, and from the Andes, in particular. The specifics aims of this research are:(1) to develop an analytical methodology for the physico-chemical characterisation of volcanic ash;(3) to propose a new ash leaching methodology that can be useful both for recent and ancient volcanic ashes (Single Batch Leaching Test, SBLT);(4) to recognize the geochemical impact occurring after the deposition of volcanic ash on the environment through leaching experiments (Batch leaching tests, Column leaching tests, and Sequential Extraction Scheme). The main conclusions extracted from this research can be summarised as follows:(1) The physico-chemical information of ashes (mainly the morphological features by SEM, grain-size distribution by laser diffraction and Potential toxic trace elements identification and quantification of the bulk ashes) highlights the main environmental concerns related to the studied ashes and it lays the foundation of the basic knowledge required to understand the ash leaching. (2) The main body of this research has been to propose a proved methodology for a single batch leaching test (SBLT) with deionised water in order to obtain information on short term leaching behaviour of volcanic ash identifying, qualitatively and quantitatively, the potentially hazardous elements being rapidly released from both recently erupted and ancient volcanic ashes. The proposed procedure is completed within few hours and its design is simple, concise and ...