Evaluation of the availability of heavy metals in lake sediments using SR-TXRF - Vives, A E S; Moreira, S; Brienza, S M B; Medeiros, J G; Zucchi, Orghêda Luiza Araujo Domingues; Barroso, R C; Nascimento Filho, Virgilio Franco do (Nuclear Instruments and Methods in Physics Research A, 2007)