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Research article2024Peer reviewedOpen access

Widespread and persistent oligotrophication of northern rivers

Nilsson, J.L.; Camiolo, S.; Huser, B.; Agstam-Norlin, O.; Futter, M.

Abstract

Phosphorus (P) is often a limiting nutrient in freshwaters and most management actions aim to reduce eutrophication associated with excess anthropogenic P inputs. Here, we report on the opposite problem, persistent and widespread oligotrophication (i.e., declining P concentrations) in northern rivers (56o-66o N) that appears unrelated to reductions in anthropogenic loading. Over the past forty years, P concentrations and fluxes in rivers draining forest dominated Swedish catchments have declined by nearly 50 %, with steeper declines in nutrient poor locations. Trends are negatively correlated with forest growth, temperature, pH and alkalinity. They are unrelated to trends in calcium, organic carbon and runoff. Declining P trends were strongest in locations draining catchments with shallow, nutrient poor soils and P concentrations in most locations are currently below estimated reference levels. These widespread and ongoing P declines highlight the need for new surface water management paradigms addressing the consequences of both nutrient scarcity and surplus.

Keywords

Climate change; Ecological quality ratio; Forest growth; Oligotrophication; Phosphorus; Recovery from acidification; Terrestrial greening

Published in

Science of the Total Environment
2024, volume: 955, article number: 177261

SLU Authors

UKÄ Subject classification

Ecology
Oceanography, Hydrology, Water Resources

Publication identifier

  • DOI: https://doi.org/10.1016/j.scitotenv.2024.177261

Permanent link to this page (URI)

https://res.slu.se/id/publ/140064