1. Geography Department, University of São Paulo, Avenida Professor Lineu Prestes, 338, Cidade Universitária, São Paulo 05508000, Brazil
2. Department of Geographical Sciences, Federal University of Pernambuco, Avenida Acadêmico Hélio Ramos, s/n, Cidade Universitária, Recife 50740530, Brazil
3. Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via Campi, 103, 41125 Modena, Italy