Annual Variability across a Decade of Observations for Dissolved Inorganic Carbon in a Coastal Setting: Results from a Time-series Station in Santa Monica Bay, CA

Despite wide efforts, assessing the role of coastal areas in the uptake and/or release of atmospheric CO2 is not easily achieved. This is due to the overall high variability in various processes that influence the air-sea gas exchange; such as upwelling, relaxation periods, El Niño/La Niña, large-scale meteorological effects including wind speed, and the complex and potentially changing role of biological uptake and remineralization on the dissolved inorganic carbon, especially under stressors such as oxygen depletion and ocean acidification. All of these processes challenge defining the coastal role as a sink or a source of atmospheric CO2. Long time series in coastal settings are rare, but crucial in understanding the above mentioned processes that might affect short –and long-term variabilities of the coastal inorganic carbon system. To this end, we will present results from a time-series in Santa Monica Bay, CA, with a focus on dissolved inorganic carbon, alkalinity, and concomitant parameters from 2003-2013, to investigate the variability of the inorganic carbon cycle and the impact on the air-sea gas exchange in a coastal setting. Some of the unexpected findings include that the Santa Monica Bay acts as an overall sink for atmospheric CO2 despite seasonal upwelling events. Surprisingly, rapid CO2 drawdowns have been observed for several years that are most likely related to biological uptake, but are occurring in the absence of major changes in macronutrient concentrations. The results further indicate substantial modulations in the dissolved inorganic carbon cycle by ENSO. Finally, based on this research, we will describe an outreach component which was developed in strong collaboration with COSEE-West and K-12 teachers to improve ocean literacy.