Fig. 4 Change in total dissolved As (both soils) and H3AsO3 (Santa soil) in the (a) flooded Santa soil, (b) flooded Palouse soil, (c) re-aerated Santa soil, and (d) re-aerated Palouse soil. Error bars denote one standard deviation. Total As, no P—{circ}; Total As, with P—{square}; H3AsO3, no P—{triangleup}; H3AsO3, with P—{triangledown}