River export of nutrients and organic matter from the North Slope of Alaska to the Beaufort Sea

Abstract

While river-borne materials are recognized as important resources supporting coastal ecosystems around the world, estimates of river export from the North Slope of Alaska have been limited by a scarcity of water chemistry and river discharge data. This paper quantifies water, nutrient, and organic matter export from the three largest rivers (Sagavanirktok, Kuparuk, and Colville) that drain Alaska's North Slope and discusses the potential importance of river inputs for biological production in coastal waters of the Alaskan Beaufort Sea. Together these rivers export 297,000 metric tons of organic carbon and 18,000 metric tons of organic nitrogen each year. Annual fluxes of nitrate-N, ammonium-N, and soluble reactive phosphorus are approximately 1750, 200, and 140 metric tons per year, respectively. Constituent export from Alaska's North Slope is dominated by the Colville River. This is in part due to its larger size, but also because constituent yields are greater in the Colville watershed. River-supplied nitrogen may be more important to productivity along the Alaskan Beaufort Sea coast than previously thought. However, given the dominance of organic nitrogen export, the potential role of river-supplied nitrogen in support of primary production depends strongly on remineralization mechanisms. Although rivers draining the North Slope of Alaska make only a small contribution to overall river export from the pan-arctic watershed, comparisons with major arctic rivers reveal unique regional characteristics as well as remarkable similarities among different regions and scales. Such information is crucial for development of robust river export models that represent the arctic system as a whole.

Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers

“…In agreement with Frey et al [9], our results show no statistically significant difference in NO 3 between permafrost-influenced and permafrost-free watersheds although the difference in NH 4 concentration is clearly pronounced. The NO 3 and NH 4 concentrations of the WSL rivers are in general agreement with other small rivers of the permafrost zone in Alaska [26]. McClelland et al [37] reported 1.2-2.4 ppm POC in the Ob River, in fair agreement with the values 0.5-2.5 ppm in this study for WSL rivers including the Ob River middle course.…”

“…Due to the high importance of the Arctic Ocean and permafrost-dominated sub-arctic continental zones in the global carbon cycle and the high vulnerability of circumpolar zones to climate warming [20][21][22], numerous studies have been devoted to the biogeochemistry of organic carbon and nutrients in large rivers of the circumpolar zone [3,[23][24][25][26][27][28][29][30]. The main source of information on long-term fluxes of dissolved and suspended material from Northern Eurasia to the Arctic Ocean is data from the Russian Hydrometeorological Survey (RHS) collected at key gauging stations of almost all major Russian Arctic rivers [31][32][33][34].…”

The fate of terrigenous dissolved organic carbon on the Eurasian shelves and export to the North Atlantic

“…For comparison, Holmes et al . [] reported annual DIN inputs from the Ob, Yenisey, Lena, and Kolyma of 0.18 Tg N. For N dynamics, particulate organic nitrogen (PON) also needs to be considered, as it can be much more abundant than tDON [ McClelland et al ., ].…”

Catchment influence on nitrate and dissolved organic matter in Alaskan streams across a latitudinal gradient

“…Thus, thawing at the southern extent of permafrost may contribute to an observed latitudinal decline in NO 3 − concentration from subarctic to arctic streams [ Jones et al ., ]. Despite these general spatial and seasonal patterns linking permafrost‐driven hydrology to mobilization of C and N from catchments, significant variation in concentration or load and composition of DOM and inorganic N occurs across catchments and among regions at high latitudes [ Holmes et al ., ; McClelland et al ., ; Roth et al ., ; Tank et al ., ; Walker et al ., ].…”