Figure 4. Stable isotope results and C/N ratios for bed sediment samples from the Tualatin River basin, showing observed ranges (shaded areas) and outliers (circled values). Lower river and Rock Creek δ¹⁵N values (filled dots) are greater than those for upper river and tributary sites (open dots). [Abbreviations: L-Su=late summer, TR=Tualatin River, number following TR=river mile location, *=sample that included deeper anoxic sediment in addition to surficial sediment].

First posted August 17, 2010