New Insights Into Legacy Phosphorus From Fractionation of Streambed Sediment

Abstract

Streambed and lake sediment was studied in Savjaan, a eutrophic mesoscale catchment (722 km(2)) in central Sweden. Triplicate sediment cores from five lakes and nine streams, ranging from headwater to fourth order, were sampled. The sediment was analyzed with a sequential extraction method, where six different phosphorus (P) fractions were measured. The results showed that streambed sediments store considerable amounts of P and in some cases have comparable P contents (g/kg DW) to lake sediment. Land use, soil type, and drainage area (location in the catchment) had a significant effect on the different P fractions found in surficial sediments. Sediment from lakes and forested headwater streams generally had high proportions of organic P and iron bound P. In larger streams located in agricultural areas on clay soils closer to the catchment outlet, with dense sediment and a relatively low proportion of organic matter, P was to a larger extent bound to calcium. Streambed sediment may be an important catchment scale P store and should be considered when modeling catchment P dynamics. The large stores of streambed legacy P should also be considered when performing ditch maintenance to avoid unnecessary mobilization of bioavailable P.

Keywords

catchment study; streambed sediment; phosphorus fractionation; internal loading; legacy phosphorus; ditch maintenance

Published in

Journal of Geophysical Research: Biogeosciences
2020, volume: 125, number: 9, article number: e2020JG005763
Publisher: AMER GEOPHYSICAL UNION

SLU Authors

• Elmi Lannergård, Emma

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Agstam-Norlin, Oskar

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Huser, Brian

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Sandström, Sara

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Rakovic, Jelena

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Futter, Martyn

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

Global goals (SDG)

SDG6 Clean water and sanitation

UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Soil Science

Publication identifier

• DOI: https://doi.org/10.1029/2020JG005763

Permanent link to this page (URI)

https://res.slu.se/id/publ/108294