Changing biogeochemical cycles of organic carbon, nitrogen, phosphorus, and trace elements in arctic rivers

Abstract

Streams and rivers are critical components of Arctic watersheds, functioning as corridors for the movement of water, carbon, and other solutes from headwater streams to larger rivers, estuaries, and the Arctic Ocean. Recent climate change in the Arctic has altered stream and river discharge, temperature, and biogeochemical processes. In this chapter, we summarize the state of research linking watershed hydrology and biogeochemical cycling in Arctic rivers, and how these processes are changing in response to changing climate and disturbance regimes (e.g., permafrost thaw, wildfire). The chapter is divided into three main sections. First, we examine hydrologic controls on stream and river chemistry, including the roles of spring snowmelt and subsurface hydrology as mediated by permafrost characteristics. Second, we summarize recent findings from the literature that describe biogeochemical processes in Arctic rivers, with particular focus on the cycling of organic carbon, nitrogen and phosphorus species, and a suite of trace elements. Third, we identify uncertainties and current gaps in our knowledge of biogeochemical processes in Arctic rivers and recommend steps forward to address these uncertainties.