Publications
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Pilla, Rachel M.; Mette, Elizabeth M.; Williamson, Craig E.; Adamovich, Boris V.; Adrian, Rita & Anneville, Orlane
[Show all 86 contributors for this article]
(2021).
Global data set of long-term summertime vertical temperature profiles in 153 lakes.
Scientific Data.
8,
p. 1–12.
doi:
10.1038/s41597-021-00983-y.
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Abstract Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of lake thermal structure in a time of rapid global and ecological change.
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Hessen, Dag Olav; Andersen, Tom; Tominaga, Koji & Finstad, Anders Gravbrøt
(2017).
When soft waters becomes softer; drivers of critically low levels of Ca in Norwegian lakes.
Limnology and Oceanography.
ISSN 0024-3590.
62(1),
p. 289–298.
doi:
10.1002/lno.10394.
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In this study, we analyzed long-term trends in calcium (Ca) concentrations for 70 Norwegian lakes spanning a broad geographical range and for a wide range of ambient drivers. A striking decline in Ca concentrations was observed during the past 30 yr. The trend was most pronounced in southern, previously acidified localities, while there were weaker and less consistent patterns for central and northern regions. For previously acidified areas, this observed decline in Ca is likely related to base cation depletion or reduced Ca mobilization as a consequence of reduced H2SO4-deposition. However, lower chloride concentrations, increased runoff and forest density (represented by Normalized Difference Vegetation Index, NDVI) also exerted strong negative impacts on Ca-concentrations. For lakes with a significant negative trend (n = 34), the average decline was −11.05% per decade, corresponding to −0.023 mg Ca L−1 yr−1. This trend may pull levels of Ca in these already Ca-deficient poor lakes toward, or below, critically low levels for a range of organisms. A somewhat paradoxical effect of the successful battle against anthropogenic acidification is thus that it may impose an increased Ca-deficiency of freshwater ecosystems.
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Finstad, Anders Gravbrøt; Andersen, Tom; Larsen, Søren; Tominaga, Koji; Blumentrath, Stefan & Wit, Heleen A. de
[Show all 8 contributors for this article]
(2016).
From greening to browning: Catchment vegetation
development and reduced S-deposition promote organic
carbon load on decadal time scales in Nordic lakes.
Scientific Reports.
6.
doi:
10.1038/srep31944.
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Increased concentrations of dissolved organic carbon (DOC), often labelled “browning”, is a current
trend in northern, particularly boreal, freshwaters. The browning has been attributed to the recent
reduction in sulphate (S) deposition during the last 2 to 3 decades. Over the last century, climate
and land use change have also caused an increasing trend in vegetation cover (“greening”), and this
terrestrially fixed carbon represents another potential source for export of organic carbon to lakes
and rivers. The impact of this greening on the observed browning of lakes and rivers on decadal time
scales remains poorly investigated, however. Here, we explore time-series both on water chemistry
and catchment vegetation cover (using NDVI as proxy) from 70 Norwegian lakes and catchments over
a 30-year period. We show that the increase in terrestrial vegetation as well as temperature and runoff
significantly adds to the reduced SO4-deposition as a driver of freshwater DOC concentration. Over
extended periods (centuries), climate mediated changes in vegetation cover may cause major browning
of northern surface waters, with severe impact on ecosystem productivity and functioning.
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Barton, David N; Andersen, Tom; Bergland, Olvar; Engebretsen, Alexander; Moe, S. Jannicke & Orderud, Geir I
[Show all 9 contributors for this article]
(2016).
Eutropia: Integrated Valuation of Lake Eutrophication Abatement Decisions Using a Bayesian Belief Network.
In Neal, Zachary P. (Eds.),
The Routledge Handbook of Applied System Science.
Routledge.
ISSN 9780415843324.
p. 297–320.
doi:
10.4324/9781315748771.
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The term “integrated valuation” is defined and its relevance is discussed in terms of bridging the
gap between cost-effectiveness analysis and economic valuation in the implementation of the
European Union Water Framework Directive. We demonstrate how to integrate benefit valuation
with the ecosystem services cascade framework using an Object-Oriented Bayesian Network
(OOBN). The OOBN is then used to assess the benefits of nutrient abatement measures across
a cascade of submodels of the driver-pressure-state-impact-response (DPSIR) chain for the
Vanemfjord lake in Morsa catchment in south-eastern Norway. The lake is part of a complex
lake system in a semi-urbanized catchment dominated by forest and agriculture. The catchment
has highly variable seasonal climatic conditions affecting nutrient run-off and algal blooms. It has
been one of the most eutrophic lakes in Norway with periodic cyanobacteria blooms, but continues
to attract a large recreational user population, despite the large variations in water quality. The
“DPSIR-OOBN” model is used as a case study of “integrated valuation” and evaluated for
its applicability for decision support in nutrient abatement. We find that the DPSIR-OOBN
model meets seven of the nine criteria we propose for “integrated valuation”. The model struggles
to meet the criteria that ecological, social and economic values should be defined consistently in
relation to impacts on lake quality. While the DPSIR-OOBN integrates from valuation methods
across an ecosystem cascade to management alternatives, it is neither a full benefit-cost analysis,
nor a multi-criteria analysis. However, we demonstrate how the DPSIR-OOBN can be used
to explore issues of consistency in scaling and weighting of different ecological, social and economic
values in the catchment system. Bayesian belief networks offer a consistent approach to analysing
how management implementation probability may determine economic valuation. We discuss the
implication of our integrated valuation not being able to account for farmer responses, in particular the incentive effects of the model not being able to predict abatement effectiveness and value. The
resolution of the nutrient monitoring data and modeling technologies that were at our disposal
are probably better in the Morsa catchment than for any other catchment of this size in Norway.
We therefore conclude that using our integrated valuation model for assessing benefits of
eutrophication abatement measures as part of the EU Water Framework Directive still lies in
the realm of utopia – euphemistically speaking a “eutropia”.
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Romarheim, Aleksandra Tmic; Tominaga, Koji; Riise, Gunnhild & Andersen, Tom
(2015).
The importance of year-to-year variation in meteorological and runoff forcing for water quality of a temperate, dimictic lake.
Hydrology and Earth System Sciences (HESS).
ISSN 1027-5606.
19(6),
p. 2649–2662.
doi:
10.5194/hess-19-2649-2015.
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Natural stochasticity can pose challenges in managing the quality of the environment, or hinder understanding of the system structure. It is problematic because unfavourable stochastic events cancel management efforts and because a favourable stochastic event may overestimate perceived success. This paper presents a variance-based modelling method that can be used to quantify the extent to which natural stochasticity can affect the target environment. We use a case study of a eutrophication assessment of a Norwegian lake, Årungen, using a lake model, MyLake, in order to present the method, and to investigate how this method could assist in answering scientific and management questions. Here we contrasted two effects of nutrient loading in runoff (partially controllable by policies) and meteorology (purely natural stochastic events), illustrated in the case study, in order to achieve the season-by-season quantification of mutually confounding factors of stochastic events. The results indicate that, for example, variation in runoff volume was most prevalent during autumn and winter, while variation in phosphorus inflow was most extensive from late winter to early spring. Thermal-related properties in the lake were well predicted by the model, and showed that the time of thermocline formation varied among years by more than 1 month, from mid-April to mid-May, whereas loading was the most important factor for phytoplankton biomass and water transparency. Mild winters and greater inputs of suspended matter and phosphorus were followed by increased phytoplankton biomass and light attenuation. These findings also suggest that future changes in the global climate may have important implications for local water management decisionmaking. The present method of disentangling mutually confounding factors is not limited to lake water quality studies and may also provide utility in other types of aquatic system modelling.
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Yang, Hong; Andersen, Tom; Dörsch, Peter; Tominaga, Koji; Thrane, Jan-Erik & Hessen, Dag Olav
(2015).
Greenhouse gas metabolism in Nordic boreal lakes.
Biogeochemistry.
ISSN 0168-2563.
126(1-2),
p. 211–225.
doi:
10.1007/s10533-015-0154-8.
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Boreal lakes are important net sources of greenhouse gases (GHGs). In this study we analyzed concentrations of CO2, CH4, N2O as well as O2, N2 and argon (Ar) from the epilimnion of 75 boreal lakes covering gradients in total organic carbon (TOC), phosphorus (P) and nitrogen (N) deposition. The Ar-corrected gas saturation deficit was used as a proxy of net metabolic changes from spring overturn to mid-summer sampling (all lakes were dimictic). Emission fluxes were calculated for CO2, CH4 and N2O based on partial pressure, water temperature and wind speed. Gas concentrations, actual and Ar-corrected, were related to lake specific properties. TOC was the main predictor of CO2 concentrations and fluxes, followed by total P, while total P and chlorophyll a governed CH4 concentrations and fluxes. Nitrogen (NO3 - or total N) were key predictors of N2O concentrations and fluxes, followed by total P. Altitude, area and depth were not strong predictors of CO2, CH4 and N2O concentrations and fluxes, likely because only lakes with an area of [1 km2 were included. CO2 molar concentrations were negatively correlated with O2 concentrations, while the slope of CO2 concentration to Ar corrected O2 deficit was 1.039. Together with the poor correlation between area-specific primary production and CO2 as well as O2, this suggests that these gases are mostly affected by catabolic processes and probably photo-oxidation in these nutrient-poor, boreal lakes investigated in this study. Increasing inputs of TOC (i.e. lake ‘‘browning’’) is likely to promote the net heterotrophy and hence emissions of all GHGs, while elevated N deposition in particular may cause elevated emissions of N2O.
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Couture, Raoul-Marie; Wit, Heleen de; Tominaga, Koji; Kiuru, Petri & Markelov, Igor
(2015).
Oxygen dynamics in a boreal lake responds to long-term changes in climate, ice phenology, and DOC inputs.
Journal of Geophysical Research (JGR): Biogeosciences.
ISSN 2169-8953.
120(11),
p. 2441–2456.
doi:
10.1002/2015JG003065.
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Boreal lakes are impacted by climate change, reduced acid deposition, and changing loads of dissolved organic carbon (DOC) from catchments. We explored, using the process-based lake model MyLake, how changes in these pressures modulate ice phenology and the dissolved oxygen concentrations (DO) of a small boreal humic lake. The model was parametrized against year-round time series of water temperature and DO from a lake buoy. Observed trends in air temperature (+0.045°C yr 1) and DOC concentration (0.11mg C L 1 yr 1, +1% annually) over the past 40 years were used as model forcings. A backcast of ice freezing and breakup dates revealed that ice breakup occurred on average 8 days earlier in 2014 than in 1974. The earlier ice breakup enhanced water column ventilation resulting in higher DO in the spring. Warmer water in late summer led to longer anoxic periods, as microbial DOC turnover increased. A long-term increase in DOC concentrations caused a decline in lake DO, leading to 15% more hypoxic days (<3mgL 1) and 10% more anoxic days (<15 μgL 1) in 2014 than in 1974. We conclude that climate warming and increasing DOC loads are antagonistic with respect to their effect on DO availability. Themodel suggests that DOC is a stronger driver of DO consumption than temperature. The browning of lakes may thus cause reductions in the oxythermal habitat of fish and aquatic biota in boreal lakes.
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Romarheim, Aleksandra Tmic; Tominaga, Koji; Riise, Gunnhild & Andersen, Tom
(2014).
Natural stochasticity vs. management effort: use of year-to year variance for disentangling significance of two mutually confounding factors affecting water quality of a Norwegian cold dimictic lake.
Hydrology and Earth System Sciences Discussions (HESSD).
ISSN 1812-2116.
11,
p. 12489–12518.
doi:
10.5194/hessd-11-12489-2014.
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Natural stochasticity can pose challenges in managing the quality of the environment, or hinder understanding of the system structure. It is problematic because unfavourable stochastic event cancels the costly management effort and because favourable stochastic event overestimates success of the management effort. This paper presents a variance-based modelling method that can be used to quantify the extent to which the natural stochasticity can affect the target environment. We use a case study of a lake water quality assessment in a Norwegian lake of Årungen, together with a lake model MyLake, in order to present the method, and how this method could assist in answering scientific and managerial questions. Specifically, the case study's goal was to disentangle the respective significance of nutrient loading (management) and weather (the confounding natural stochasticity). Many scientifically and managerially relevant understandings have been revealed. For example, variation in runoff volume was most prevalent during autumn and winter, while variation in phosphorus inflow was most extensive from late winter to early spring. Thermal related properties in the lake were mostly determined by weather conditions, whereas loading was the most important factor for phytoplankton biomass and water transparency. Mild winters and greater inputs of suspended matter and phosphorus were followed by increased phytoplankton biomass and light attenuation. These findings suggest also that future changes in the global climate may have important implications for local water management decision-making. The present method of disentangling mutually confounding factors is not limited to lake water quality studies and therefore should provide certain utility in other application field of modelling. This discussion paper is/has been under review for the journal Hydrology and Earth System Sciences (HESS). Please refer to the corresponding final paper in HESS if available.
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Couture, Raoul-Marie; Tominaga, Koji; Starrfelt, Jostein; Moe, S. Jannicke; Kaste, Øyvind & Wright, Richard Frederic
(2014).
Modelling phosphorus loading and algal blooms in a Nordic agricultural catchment-lake system under changing land-use and climate.
Environmental Science: Processes & Impacts.
ISSN 2050-7887.
16(7),
p. 1588–1599.
doi:
10.1039/c3em00630a.
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A model network comprising climate models, a hydrological model, a catchment-scale model for phosphorus biogeochemistry, and a lake thermodynamics and plankton dynamics model was used to simulate phosphorus loadings, total phosphorus and chlorophyll concentrations in Lake Vansjø, Southern Norway. The model network was automatically calibrated against time series of hydrological, chemical and biological observations in the inflowing river and in the lake itself using a Markov Chain Monte-Carlo (MCMC) algorithm. Climate projections from three global climate models (GCM: HadRM3, ECHAM5r3 and BCM) were used. The GCM model HadRM3 predicted the highest increase in temperature and precipitation and yielded the highest increase in total phosphorus and chlorophyll concentrations in the lake basin over the scenario period of 2031–2060. Despite the significant impact of climate change on these aspects of water quality, it is minimal when compared to the much larger effect of changes in land-use. The results suggest that implementing realistic abatement measures will remain a viable approach to improving water quality in the context of climate change.
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Couture, Raoul-Marie; Wit, Heleen de; Tominaga, Koji; Kiuru, Petri & Markelov, Igor
(2015).
Modelling the impact of increasing dissolved organic carbon load on seasonal anoxia in a boreal humic lake.
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Boreal lakes are impacted by climate change, reduced acid deposition and changing loads of dissolved organic carbon (DOC) from the catchment. We set to explore how these changes, in particular the increasing DOC load, modulate ice phenology and dissolved oxygen (DO) of a boreal humic lake located in southeastern Norway. Observed trends in daily air temperature (+0.045 oC yr-1) and weekly DOC concentration (0.1 mg C yr-1, +1% annually) measured over the past 40 years at the study site were used as forcings for the lake model MyLake. The model was parametrized against year-round time-series of water temperature and DO from a high-frequency lake buoy. A backcast of ice freezing and break-up dates to 1974 reveals that ice break-up occurs on average 8 days earlier in 2014 than in 1974. An earlier ice break-up enhances water column ventilation, resulting in higher DO in the spring. Later in the season, warmer water in late summer lead to longer anoxic periods, as microbial DOC turnover increases. Long-term increase in DOC concentrations causes decline in lake DO, leading to 15% more hypoxic days (< 3 mg L-1) and 10% more anoxic days (< 15 ug L-1) in 2014 than in 1974. We conclude that climate warming and increasing DOC loads are antagonistic with respect to their effect on DO availability. The model suggests that DOC is a stronger driver of DO consumption than temperature. DOC increase thus has the potential to reduce the oxythermal habitat of fish and aquatic biota in boreal lakes.
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Tominaga, Koji
(2013).
Warming and eutrophication: Similarities and discrepancies in their impact on lake ecosystems.
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Tominaga, Koji; Finstad, Anders Gravbrøt; Kaste, Øyvind & Andersen, Tom
(2012).
Future climate impact on lakes in Fennoscandia: A dynamic mechanistic modelling approach.
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Tominaga, Koji; Finstad, Anders Gravbrøt; Kaste, Øyvind & Andersen, Tom
(2012).
From changes in climate to changes in lake thermal status.
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Engebretsen, Alexander Melvold; Tominaga, Koji & Barton, David Nicholas
(2012).
Modellering av næringsstofftransport i Morsa vassdraget - Kobling av modellers usikkerhet og bruk av Bayesianske nettverk.
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Tominaga, Koji
(2010).
Ensemble model framework for lake ecosystem modelling - case study from acidification modelling.
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While the structural details may vary, there are many environmental models with the same functionality. The lake ecosystem modelling community is no exception; for example, many models are able to simulate policy relevant variables such as lake nutrient concentrations. Despite this parallel situation, only one model is often chosen and applied to a given modelling problem. This may pose serious policy or management implications, if lake ecosystem models aspire to change their role as a ‘research tool’ to a ‘policy tool’. In this presentation, experiences in incorporating multiple acidification ecosystem models for a single catchment are illustrated. Benefits and challenges for such a study are discussed, with an emphasis of relevance to lake ecosystem modelling.
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Tominaga, Koji; Andersen, Tom; Vogt, Rolf David & Saloranta, Tuomo
(2013).
Lake modelling - an interdisciplinary context.
Faculty of Mathematics and Natural Sciences, University of Oslo.
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Published
Nov. 3, 2010 3:34 PM
- Last modified
Mar. 28, 2011 12:22 PM
