Recent trends in the chemistry of major northern rivers signal widespread Arctic change
Résumé
Rivers integrate processes occurring throughout their watersheds and aretherefore sentinels of change across broad spatial scales. River chemistryalso regulates ecosystem function across Earth’s land–ocean continuum,exerting control from the micro- (for example, local food web) to the macro-(for example, global carbon cycle) scale. In the rapidly warming Arctic, awide range of processes—from permafrost thaw to biological uptake andtransformation—might reasonably alter river water chemistry. Here weuse data from major rivers that collectively drain two-thirds of the ArcticOcean watershed to assess widespread change in biogeochemical functionwithin the pan-Arctic basin from 2003 to 2019. While the oceanward flux ofalkalinity and associated ions increased markedly over this time frame, nitrateand other inorganic nutrient fluxes declined. Fluxes of dissolved organiccarbon showed no overall trend. This divergence in response indicatesthe perturbation of multiple processes on land, with implications forbiogeochemical cycling in the coastal ocean. We anticipate that these findingswill facilitate refinement of conceptual and numerical models of currentand future functioning of Arctic coastal ecosystems and spur research onscale-dependent change across the river-integrated Arctic domain.
Domaines
Sciences de l'environnement
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