DANTAS, R. DA C.; NAVONI, J. A.; FERREIRA, D. DE M.; COSTA, T. F. DA; MEDEIROS, S. R. B. DE; AMARAL, V. S. DO. <b&gt;Influence of natural radon and metal contamination on surface water quality from a Brazilian Semiarid Region. Acta Scientiarum. Biological Sciences, v. 39, n. 3, p. 275-282, 18 set. 2017.