Chemical sound absorption in sea water cannot be considered the sum of independent relaxation processes because many equilibria have common ions. Effects of coupling on the MgCO30 and MgB(OH)+4 relaxations can be explained as simple buffer reactions that equilibrate rapidly and follow the slower reactions. The B(OH)3 relaxation, however, is explained by a different mechanism involving exchange with the HCO3−/CO32− system.

The low-frequency boric acid relaxation mechanism in seawater has been identified as an acid-base exchange between the B(OH)3/B(OH)−4 and HCO−3/CO2−3 equilibria. Ion pairing with Ca2+ is also involved and a coupled-system model is proposed. Supporting experimental data for the CO2 exchange mechanism are presented. Similar exchanges with ammonia and silicic acid are also investigated.