OS22A-04
Chemical and Biological Impacts of Ocean Acidification Along the West Coast of North America
Tuesday, 15 December 2015: 11:05
3011 (Moscone West)
Richard A Feely, NOAA Pacific Marine Environmental Laboratory, Seattle, WA, United States
Abstract:
The continental shelf region off the Washington-Oregon-California coast is seasonally exposed to water with a low aragonite saturation state by coastal upwelling of CO
2-rich waters. To date, the spatial and temporal distribution of anthropogenic CO
2 (C
anth) contribution to the CO
2-rich waters is largely unknown. Here we use an adaptation of the linear regression approach described in Feely et al. (2008) to utilize the GO-SHIP Repeat Hydrography data set from the northeast Pacific to establish an annually updated relationship between C
anth and potential density. This relationship was then used with the NOAA Ocean Acidification Program West Coast cruise data sets from 2007, 2011, 2012 and 2013 to determine the spatial variations of C
anth in the upwelled water. Our results show large spatial differences in C
anth in surface waters along the coast with the lowest values (40-45 µmol kg
-1) in strong upwelling regions of off northern California and southern Oregon and higher values (50-70 µmol kg
-1) to the north and south of this region. C
anth contributes an average of about 70 % of the increased amount of dissolved inorganic carbon in the upwelled waters at the surface relative to what would be expected from physical circulation and exchange with a preindustrial atmosphere alone. In contrast, C
anth contributes an average of about 31%, and 16% of the increased amount of dissolved inorganic carbon at 50 m depth, and at 100 m depth respectively. The remaining contributions are either due to respiration processes in the water that was upwelled and transported to coastal regions or respiration processes that occurs locally during the course of the upwelling season. The uptake of C
anth has caused the aragonite saturation horizon to shoal by approximately 30-50 m since preindustrial period so that the undersaturated waters are well within the regions of the continental shelf that affect the biological communities.
