Abstract
Over the past several years researchers have been working to synthesize the WOCE/
JGOFS global CO2 survey data to better understand carbon cycling processes in the
oceans. The Pacific Ocean data set has over 35,000 sample locations with at least two
carbon parameters, oxygen, nutrients, CFC tracers, and hydrographic parameters. In this
paper we estimate the in situ CaCO3 dissolution rates in the Pacific Ocean water column.
Calcium carbonate dissolution rates ranging from 0.01–1.1 mmol kg1 yr1 are observed
in intermediate and deepwater beginning near the aragonite saturation horizon. In the
North Pacific Intermediate Water between 400 and 800 m, CaCO3 dissolution rates are
more than 7 times faster than observed in middle and deep water depths (average = 0.051
mmol kg1 yr1). The total amount of CaCO3 that is dissolved within the Pacific is
determined by integrating excess alkalinity throughout the water column. The total
inventory of CaCO3 added by particle dissolution in the Pacific Ocean, north of 40S, is
157 Pg C. This amounts to an average dissolution rate of approximately 0.31 Pg C yr1.
This estimate is approximately 74% of the export production of CaCO3 estimated for the
Pacific Ocean. These estimates should be considered to be upper limits for in situ
carbonate dissolution in the Pacific Ocean, since a portion of the alkalinity increase
results from inputs from sediments.