Graph: Oxygen Isotope Ratios of Dissolved Nitrate from Sites in the Puget Sound

Graph: Oxygen Isotope Ratios of Dissolved Nitrate from Sites in the Puget Sound
Oxygen isotope ratios of dissolved nitrate (NO3-) from the 34 river and marine sites in the Puget Sound in 2014. Colors indicate month of sampling: Blue = February, Gray = April, Light Red = May, and Dark Red = June. The black line is the expected relationship between δ17O and δ18O (δ17O = 0.52 * δ18O) in the absence of atmospheric NO3-. Values falling above the line indicate a higher fraction of atmospheric NO3- present in that sample. Circles are freshwater samples while square are marine.