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Research article2025Peer reviewed

Usual suspects meet mission impossible: Nutrient losses and effects of mitigation measures on a coastal catchment in the Baltic Sea region

Djodjic, Faruk; Golovko, Oksana; Kumblad, Linda; Rydin, Emil; Sandstrom, Sara; Widen-Nilsson, Elin

Abstract

Eutrophication of coastal areas is a global problem. A full-scale coastal remediation project was initiated in Bj & ouml;rn & ouml;fj & auml;rden bay in the Stockholm archipelago in 2011. Measures to reduce external nutrient inputs from the surrounding catchment (15 km2) targeted agriculture, on-site wastewater treatment facilities, and horse keeping. The effects were evaluated at 22 water quality monitoring stations over 11 years (2012-2022) to determine temporal trends in nutrient concentrations, spatial correlations within and between monitored sub-catchments, and effects of individual mitigation measures at local and catchment scale. The effect of individual measures varied from no significant effect to significant nutrient decreases (21% reduction in dissolved P concentrations in one lime filter) or increases (11% higher concentrations in total P in one constructed wetland). However, few significant trends were detected at sub-catchment outlet stations. Tailored placement, design, dimensioning, and maintenance of implemented mitigation measures are needed to improve their nutrient retention effect.

Keywords

Agriculture; Eutrophication; Mitigation; Nitrogen; On-site wastewater treatment; Phosphorus

Published in

AMBIO: A Journal of the Human Environment
2025
Publisher: SPRINGER

SLU Authors

UKÄ Subject classification

Water Treatment
Environmental Sciences and Nature Conservation

Publication identifier

  • DOI: https://doi.org/10.1007/s13280-025-02132-w

Permanent link to this page (URI)

https://res.slu.se/id/publ/140644