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 (r 2 = 0.78), DON (r 2 = 0.55) and DOP (r 2 = 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.

Increasing concentration of polyunsaturated fatty acids in browning boreal lakes is driven by nuisance alga Gonyostomum

“…The dominance of cyanobacteria in browning temperate lakes may be related to longer and warmer growing season and higher nutrient levels or less acidic conditions compared to the naturally brown boreal lakes in the current study (Palviainen et al 2016, Senar et al 2019. This is supported by the results from Lake € At€ ask€ o in the current study, which was the only lake with any relevant anthropogenic input of carbon and nutrients (Palviainen et al 2016). Lake € At€ ask€ o was distinct from the other high DOC lakes due to its absence of Gonyostomum and correspondingly lower phytoplankton biomass and PUFA concentration (although not as low as in the oligotrophic lakes), which is in accordance with previous studies (Bergstr€ om and Karlsson 2019, Senar et al 2019.…”

“…Cyanobacteria do not contain any EPA or DHA but may contain C18 PUFA (Los and Mironov 2015), thus maintaining some level of PUFA production (Strandberg et al 2015b). The dominance of cyanobacteria in browning temperate lakes may be related to longer and warmer growing season and higher nutrient levels or less acidic conditions compared to the naturally brown boreal lakes in the current study (Palviainen et al 2016, Senar et al 2019. This is supported by the results from Lake € At€ ask€ o in the current study, which was the only lake with any relevant anthropogenic input of carbon and nutrients (Palviainen et al 2016).…”

Variation in dissolved organic matter (DOM) stoichiometry in U.K. freshwaters: Assessing the influence of land cover and soil C:N ratio on DOM composition

“…The low DOC : DON and DOC : DOP ratios observed in catchments where agricultural and heavily fertilized land classifications dominate (IG and AH) is a pattern consistent within the wider literature (Aitkenhead‐Peterson et al ; Graeber et al ; Heinz et al ; Williams et al ). Removal of crop residues and well‐maintained field drainage systems in areas with intensive arable production have been found to reduce soil organic matter content while also reducing contact time between water and soil organic material, thus reducing organic matter dissolution rates (Mattsson et al ; Palviainen et al ). In addition, physical disturbances from agricultural practices and higher soil pH have been shown to increase soil DOM turnover rates (Leifeld et al ).…”

“…However, catchments impacted by agricultural intensification (Graeber et al ; Yates et al ), subject to urbanization (Aitkenhead‐Peterson et al ), or heavily impacted by sewage treatment works (STWs; Sickman et al ; Yates et al ), have demonstrated increases in both DOM concentration and its relative nutrient richness (measured as DON and DOP). Not only is DOM concentration therefore known to vary in relation to catchment character (Palviainen et al ) but also a wide range of studies have observed compositional differences in DOM related to specific catchment sources (Mattsson et al ; Spencer et al ; Hernes et al ; Yates et al ). These differences reflect the influence of land use and management, soil type, and hydrological function in controlling the rates of microbial decomposition, nutrient cycling, uptake within the soil, and the net flux of DOM from different soil horizons to adjacent waters (Austnes et al ).…”

Dynamics of dissolved carbon and nitrogen in decomposing boreal mor and peat as affected by enchytraeid worms

“…Combining the results with existing literature including data regarding the average properties of head water catchments in Central Finland (Korkalainen et al 2007), and a biodegradation equation with parameters (Kalbitz et al 2003a), transport time, role of biodegradation in the transport and the DOC export load to watercourse can be produced. By means of more complex initial information, such as water flow path characteristics of the catchment, hydraulic characteristics, soil types, and experimental parameters, more precise computational remarks can be obtained (Palviainen et al 2016). The calculation in II indicates that enchytraeids can increase the DOC export load from 14 to 20 ha -1 yr -1 .…”