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Doktorsavhandling2024Öppen tillgång

Carbon, nitrogen, and phosphorus in headwater streams of boreal catchments : long term data analysis, consequences of anthropogenic management and ways to mitigate disturbances

Mosquera, Virginia

Sammanfattning

The relative supply of carbon (C), nitrogen (N), and phosphorus (P) to freshwater ecosystems is of fundamental importance to aquatic productivity, nutrient cycling, and food web dynamics, which can ultimately influence ecosystem services, recreational values and the provision of drinking water. Using over ten years of water quality data and field experiments, this thesis focuses in understanding the simultaneous supply of C, N and P from boreal catchments to freshwater ecosystems, how this natural supply is disrupted by forest management activities and evaluating a way to mitigate disturbances. Our findings show that catchment characteristics directly influenced the opposing mobilization response of inorganic N and P and organic C and N to increases in flow. Conversely, regardless of catchment characteristics, we found a widespread decline for inorganic P and N in streams over time, co-occurring with an increase in DOC concentration and revealing changes in the ratio of energy to nutrient supply. Alongside, catchments with forest operations, specifically clear cut, showed an increase in the exports of organic C and N and inorganic N and P, yet if followed by ditch cleaning, organic and inorganic nutrient concentration decreased. Finally, we found that the disturbance in C and N concentration could be mitigated using a biochar filter, if the nutrient concentration is high enough. Given the critical interplay between the supply of resources from catchments and their demand in aquatic ecosystems, understanding the spatial-temporal variability of C, N, and P concentrations and their ratios is key to predicting how northern rivers and downstream lakes may respond to ongoing and future environmental changes.

Nyckelord

carbon; nitrogen; phosphorus; boreal catchments; water quality

Publicerad i

Acta Universitatis Agriculturae Sueciae
2024, nummer: 2024:79ISBN: 978-91-8046-370-6, eISBN: 978-91-8046-406-2Utgivare: Swedish University of Agricultural Sciences