The Arctic Great Rivers Observatory: Long Term Trends in River Chemistry Diagnose Multi-Faceted Northern Change
Abstract
Large rivers integrate processes occurring throughout their watersheds and are therefore sentinels of change across broad spatial scales. River chemistry also regulates function across Earth's land-ocean continuum, exerting control on processes ranging from biological production to the carbon cycle. In the rapidly warming Arctic, a wide range of processes might reasonably alter the chemical signature of river water. However, it is unknown how the land-ocean flux of waterborne constituents is changing at the pan-Arctic scale. Here, we utilize a nearly two decade record of water chemistry that we have collected via the Arctic Great Rivers Observatory, coupled with established discharge records, to show profound shifts in the concentration and transport of biogeochemical constituents at the mouths of large Arctic rivers. Our data encompass the six largest rivers that affect the Arctic Ocean, which together capture two-thirds of the Arctic drainage basin. While some constituents increase substantially at the pan-Arctic scale (alkalinity and associated ions), others decline (nitrate, suspended solids) or remain largely unchanged (dissolved organics). These clear but divergent trends diagnose multi-systems perturbation throughout the pan-Arctic basin and indicate that diverse processes act in concert to affect the flux of biogeochemical constituents from land to ocean. We use our findings to consider how drivers ranging from permafrost thaw to temperature-driven changes in autotrophic and heterotrophic activity may play out across constituent classes, and assess key knowledge gaps. While process models will help diagnose the most critical drivers of change and how these vary among constituents and with geographic scale, our results underscore the need for rapid attention to Earth's warming climate, its multiplicative effects in the north, and the importance of long-term observations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.B22B..01T