Using stable isotopes to understand multi-scale changes in aquatic biogeochemistry in the human-impacted San Francisco Bay and Sacramento-San Joaquin Delta, California

Abstract:

Changes in water quality in the San Francisco Bay and Sacramento-San Joaquin Delta (SF Bay-Delta) are linked to local, regional, and global scale processes operating at different time scales. To better understand variability in biogeochemical processes at a range of these time scales, we examined multiple existing nutrient and isotopic datasets across transects spanning SF Bay-Delta waters. Data were binned into multiple time-steps to explore temporal changes and spatial differences in carbon (C) and nitrogen (N) biogeochemistry in this system. Annual and monthly binned isotopic data provided new information on dominant particulate organic matter sources and biogeochemical processes operating at different time steps. These data also showed dynamic spatial dimensions to SF Bay-Delta biogeochemistry. Future work will focus on examining master controls on these changes to provide new insight into SF Bay-Delta C and N sources, transformations, transport, uptake, and ultimate fate.