The effect of varying water pH on the acidification of expired water

Acidification of expired water was studied in rainbow trout exposed to water of pH9.91, 6.80 (control) and 3.88. For the high-pH and the control exposures, the water flowing over the gills was acidified because of the dominant effect of CO2 hydration. During the low-pH treatment, the water was alkalized because of ammonium ion formation and perhaps bicarbonate dehydration. Carbon dioxide excretion was not significantly affected by the high-pH and low-pH treatments but ammonia accumulated in the plasma in both cases