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Rapid changes in land use, pollution inputs, and climate are altering the quantity, timing and form of materials delivered from watersheds to estuaries. To better characterize these alterations simultaneous measurements of biogeochemical conditions in watersheds and estuaries over a range of times scales are needed. We examined the strength of watershed-estuarine biogeochemical coupling using data of in situ measurements of nitrate, terrestrial dissolved organic carbon (DOC) and chloride collected over a seven-month period in a nitrogen impaired estuary in the northeastern US. The watershed was observed exerting strong control over concentrations of terrestrially derived DOC in the estuary, attributable to relative homogeneity of watershed sources derived from forested land use combined with relatively conservative behavior in estuarine waters. Estuarine nitrate patterns were more complex, suggesting the influence of heterogeneous watershed distribution of non-point and point sources and high reactivity of nitrate in the estuary. Understanding estuarine biogeochemical patterns will be advanced through greater use of simultaneous sub-hourly measurements of inflows, salinity and water quality estuaries and their upstream watersheds.
Earth Systems Research Center
Grant/Award Number and Agency
This research was funded in part by NSF (EPS 1101245), NH Sea Grant (NOAA NA10OAR4170082), NH Agricultural Experiment Station and UNH ESRC’s Iola Hubbard Endowment for Climate Change. This is AES Scientific Contribution Number 2675 supported by the USDA NIFA Hatch Project 0225006.
Mulukutla, Gopal K.; Wollheim, Wilfred; Salisbury, Joseph; Carey, Richard O.; Gregory, Thomas; and McDowell, William H., "High Frequency Concurrent Measurements in Watershed and Impaired Estuary Reveal Coupled DOC and Decoupled Nitrate Dynamics" (2021). Earth Systems Research Center. 216.