Chemical composition of rivers in Alaska’s Arctic Network, 2013–2014
O'Donnell JA, Aiken GR, Trainor TP, Douglas TA, Butler KD. 2015. Chemical composition of rivers in Alaska’s Arctic Network, 2013–2014. Natural Resource Data Series. NPS/ARCN/NRDS—2015/809. National Park Service. Fort Collins, Colorado
The chemical composition of rivers is an important characteristic that can have considerable influence on aquatic ecosystem function and response to landscape change. Here, we report findings from a two-year pilot study aimed at characterizing the chemical composition of rivers in National Park Service lands of the Arctic Inventory and Monitoring Network (ARCN). We collected water samples from 57 rivers during the summer-autumn flow period (June-September) during the 2013 and 2014 field seasons. An additional five rivers were re-sampled during winter flow in March 2014. Water samples were analyzed for dissolved organic matter (DOM) composition, nutrient concentrations, major cations and anions, and water stable isotopes. We observed considerable variation in chemical composition across study sites within ARCN parks. For instance, mean dissolved organic carbon (DOC) concentration varied across ARCN parks, ranging from 2 to 8 mgC L-1. DOM character also varied across parks, as indicated by measurements of specific ultraviolet absorbance (SUVA254) and through chemical fractionation of DOM. Both nitrogen and phosphorus concentrations were consistently low in all samples, indicating oligotrophic conditions and low production rates. Base cation concentrations and water stable isotopes are useful indicators of watershed hydrogeology and the relative influence of groundwater across rivers. We observed high concentrations of dissolved iron in rivers of Kobuk Valley National Park. This elevated iron appears to be influenced by the amount and composition of DOM leaching from local pristine soils into the rivers. Overall, rivers in the ARCN parks appear to be unimpaired with respect to carbon, nutrients and trace metals. However, Arctic rivers may be vulnerable to climate-driven changes in the soil thermal regime, hydrology, and disturbance (permafrost thaw, erosion, wildfire), all of which can alter the chemical composition of surface water. Future monitoring of ARCN rivers should be designed to detect chemical and hydrologic properties across space and time, both as a means of assessing these vulnerabilities and for improving watershed management activities.
- Type
- Published Report
- Authors
- O'Donnell, Jonathan; Aiken, George; Trainor, Thomas; Douglas, Thomas; Butler, Kenna
- Date of Issue
- 2015-05
- Publisher
- National Park Service
- Units
- ARCN , BELA , CAKR , GAAR , KOVA , NOAT , NRSS
- Keywords
- Aquatic, ARCN, Arctic Network, Chemical, dissolved organic matter, dom, Hydrogeology, Isotopes, National Park Service, Nitrogen, Nutrient, River, Water
- Subjects
- Ecological Framework: Water | Hydrology | Surface Water Dynamics , Ecological Framework: Water | Water Quality | Water Chemistry