Cadmium tolerances of Chlamydomonas reinhardtii (A), Cyanidioschyzon merolae (B), and Synechococcus leopoliensis (C) exposed to 100, 100, and 2 μM Cd(II), respectively, when supplemented with sulfur containing compounds. No added Cd(II) (), Cd(II) alone (), and Cd(II) with the following additions; sulfate (), prefed sulfate plus sulfate (), sulfite (), prefed sulfite plus sulfite (), cysteine (), and prefed cysteine plus cysteine (). Means are presented (n = 4). SE always less than 7%. Where growth curves are not visible, they are at the same values as the lowest presented.