Alkalinity values in the top few hundred meters in Baffin Bay were about 100 μeq kg—1 above those expected from deeper values when the effect of salinity is removed. This “excess” alkalinity is attributed to calcium carbonate that precipitated from brines in sea ice and was subsequently reintroduced into the water column when the ice melted. The “excess” alkalinity is then used to estimate the amount of sea ice meltwater formed in Baffin Bay.