title: Predicting the export and concentrations of organic carbon, nitrogen and phosphorus in boreal lakes by catchment characteristics and land use: A practical approach.
abstract: The majority of C, N and P in boreal lakes are in organic form. Organically bound nutrients are released through biodegradation or photodegradation which affects the water quality, eutrophication and greenhouse gas emissions of lakes. We tested whether open land-use data combined with land-use-specific export coefficients can be used to predict total organic carbon (TOC), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) loading and lake water concentrations. Using data from 12 lake catchments in eastern Finland, we found that land use and management of the catchment explained a substantial proportion of the variations in TOC (r2= 0.78), DON (r2= 0.55) and DOP (r2= 0.80) concentrations between lakes. The computation does not account for in-lake processes, which are reflected as mismatch between the predicted and observed concentrations. However, this simple practical approach is useful in ranking lakes according to their water quality. The results indicated that natural sources dominate TOC, DON and DOP exports; the background leachings accounted for 57-99 %, 48-96 % and 55-99 % of TOC, DON and DOP export, respectively. The proposed method has promise as a practical decision support tool for assessing the impacts of land use on water quality. The results showed that possibilities to control TOC, DON and DOP loading to surface waters are limited to catchments where the peatland proportion is low and anthropogenic sources significant.
authors.affiliation: Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014, Helsinki, Finland. marjo.palviainen@helsinki.fi.
authors.forename: Marjo
authors.initials: M
authors.lastname: Palviainen
authors.affiliation: Natural Resources Institute Finland (Luke), P.O. Box 68, 80101, Joensuu, Finland.
authors.forename: Ari
authors.initials: A
authors.lastname: Laurén
authors.affiliation: Natural Resources Institute Finland (Luke), P.O. Box 18, 01301, Vantaa, Finland.
authors.forename: Samuli
authors.initials: S
authors.lastname: Launiainen
authors.affiliation: Natural Resources Institute Finland (Luke), P.O. Box 68, 80101, Joensuu, Finland.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Piirainen
mesh_terms: D000383:Agriculture; D004784:Environmental Monitoring / Q000379:methods*; D005387:Finland; D005544:Forecasting; D065928:Forests; D060106:Lakes / Q000737:chemistry*; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012995:Solubility
chemical_list: D009930:Organic Chemicals; D010758:Phosphorus; D009584:Nitrogen
keywords: Carbon; Land use; Organic nitrogen; Organic phosphorus; Specific export coefficient; Water quality