Export of DOM from Boreal Catchments: Impacts of Land Use Cover and Climate

• Published in: Biogeochemistry Vol. 76; no. 2; pp. 373 - 394
• Main Authors: Mattsson, T, Kortelainen, P, Raike, A
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.11.2005; Springer Nature B.V
• Subjects: Agricultural land; agricultural watersheds; Aquatic ecosystems; Boreal forests; Catchment areas; dissolved organic carbon; Dissolved organic matter; dissolved organic nitrogen; Dissolved organic phosphorus; Earth sciences; Earth, ocean, space; Exact sciences and technology; Food webs; forest soils; forested watersheds; Geochemistry; hydrochemistry; Hydrology; Hydrology. Hydrogeology; Lakes; Land use; losses from soil; Marine and continental quaternary; Mineralogy; Nitrogen; Nutrient cycles; Organic carbon; Organic foods; Organic nitrogen; Peatlands; River basins; Rivers; Silicates; Soil pollution; surface water; Surficial geology; total nitrogen; total organic carbon; total organic nitrogen; Upstream; Water geochemistry; Watersheds; Finland; Scandinavia; stream transport; Organic matter; latitude; nutrients; drainage basins; land use; modern; hydrochemistry; peat bogs; dissolved materials; lakes; correlation coefficient; export; organic carbon; retention; phosphorus; Europe; nitrogen; climate; transport; Fluxes; Carbon; River basins; ecosystems; organic materials; statistical analysis; seasonal variations
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-005-6897-x

Dissolved organic matter (DOM) is an important fraction in carbon (C) and nutrient budgets for aquatic ecosystems and can have broad effects on food webs and nutrient cycling. To look at the role land use cover and climate might play in DOM transport from the boreal region, the export of total organic carbon (TOC), total organic nitrogen (TON) and dissolved organic phosphorus (DOP) was estimated for Finnish main rivers and their sub-catchments, altogether 86 catchments, situated between latitudes 60° N and 69° N and covering 297,322 km⁲, 88% of the total area of Finland. On an average, 94% of the TOC, 90% of the total nitrogen (TN) and 40% of the total phosphorus (TP) in Finnish rivers was in a dissolved form. The majority of the DOM export from Finnish catchments consists of organic C. The TOC export increased with increasing peatland proportion (r = 0.39, p = 0.003), while TON export increased with the increasing percentage of agricultural land (r = 0.60, p &lt 0.001). Although upstream lakes covered only on average 9% of the catchment area, they were the most important predictor for TOC, TON and DOP export (r = -0.83, r = -0.82 and r = -0.61, respectively). The higher the upstream lake percentage, the lower the export indicating organic matter retention in lakes.