Modelled Nitrosamine and Nitramine concentrations in Lake Elvåga following amine-based CO2 Capture at FOV Waste Incineration Plant at Klemetsrud

Project Manager Cathrine Brecke GundersenFuture levels of the carcinogenic- and potentially carcinogenic nitrosamines (NSAs) and nitramines (NAs), respectively, were modelled in the drinking water source, Lake Elvåga following the planned full-scale amine-based CO2 capture at the Oslo waste incineration plant. A high-resolution and dynamic catchment model (INCA-Contaminants) was combined with a lake model add-on. NSA and NA deposition rates (provided from COWI/Norsk Energi/CERC) were combined with site specific information (hydrology and climate), and literature values of NSA and NA bio- and photodegradation rates and physiochemical parameters. The three scenarios, “best”, “likely”, and “worst” cases were created to capture the uncertainty of key parameters. Three years of full-scale CO2 capture resulted in maximum annual average sums of NSAs and NAs in the lake water at 0.24, 3.3, and 4.4 ng L-1, for the three scenarios, respectively. For the NSAs, photodegradation was an efficient depletion pathway, nearly balancing out the input rates. Lake water levels of NAs increased with time due to the lack of an efficient depletion pathway. Seasonal variation was evident in both the NSA and NA concentrations and this should be considered for potential future monitoring programs.COWIpublishedVersio

Forecasting water temperature in lakes and reservoirs using seasonal climate prediction

ABSTRACT: Seasonal climate forecasts produce probabilistic predictions of meteorological variables for subsequent months. This provides a potential resource to predict the influence of seasonal climate anomalies on surface water balance in catchments and hydro-thermodynamics in related water bodies (e.g., lakes or reservoirs). Obtaining seasonal forecasts for impact variables (e.g., discharge and water temperature) requires a link between seasonal climate forecasts and impact models simulating hydrology and lake hydrodynamics and thermal regimes. However, this link remains challenging for stakeholders and the water scientific community, mainly due to the probabilistic nature of these predictions. In this paper, we introduce a feasible, robust, and open-source workflow integrating seasonal climate forecasts with hydrologic and lake models to generate seasonal forecasts of discharge and water temperature profiles. The workflow has been designed to be applicable to any catchment and associated lake or reservoir, and is optimized in this study for four catchment-lake systems to help in their proactive management. We assessed the performance of the resulting seasonal forecasts of discharge and water temperature by comparing them with hydrologic and lake (pseudo)observations (reanalysis). Precisely, we analysed the historical performance using a data sample of past forecasts and reanalysis to obtain information about the skill (performance or quality) of the seasonal forecast system to predict particular events. We used the current seasonal climate forecast system (SEAS5) and reanalysis (ERA5) of the European Centre for Medium Range Weather Forecasts (ECMWF). We found that due to the limited predictability at seasonal time-scales over the locations of the four case studies (Europe and South of Australia), seasonal forecasts exhibited none to low performance (skill) for the atmospheric variables considered. Nevertheless, seasonal forecasts for discharge present some skill in all but one case study. Moreover, seasonal forecasts for water temperature had higher performance in natural lakes than in reservoirs, which means human water control is a relevant factor affecting predictability, and the performance increases with water depth in all four case studies. Further investigation into the skillful water temperature predictions should aim to identify the extent to which performance is a consequence of thermal inertia (i.e., lead-in conditions).This is a contribution of the WATExR project (watexr.eu/), which is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by MINECO-AEI (ES), FORMAS (SE), BMBF (DE), EPA (IE), RCN (NO), and IFD (DK), with co-funding by the European Union (Grant 690462 ). MINECO-AEI funded this research through projects PCIN- 2017-062 and PCIN-2017-092. We thank all water quality and quantity data providers: Ens d’Abastament d’Aigua Ter-Llobregat (ATL, https://www.atl.cat/es ), SA Water ( https://www.sawater.com. au/ ), Ruhrverband ( www.ruhrverband.de ), NIVA ( www.niva.no ) and NVE ( https://www.nve.no/english/ ). We acknowledge the contribution of the Copernicus Climate Change Service (C3S) in the production of SEAS5. C3S provided the computer time for the generation of the re-forecasts for SEAS5 and for the production of the ocean reanalysis (ORAS5), used as initial conditions for the SEAS5 re-forecasts

Sources of skill in lake temperature, discharge and ice-off seasonal forecasting tools

Despite high potential benefits, the development of seasonal forecasting tools in the water sector has been slower than in other sectors. Here we assess the skill of seasonal forecasting tools for lakes and reservoirs set up at four sites in Australia and Europe. These tools consist of coupled hydrological catchment and lake models forced with seasonal meteorological forecast ensembles to provide probabilistic predictions of seasonal anomalies in water discharge, temperature and ice-off. Successful implementation requires a rigorous assessment of the tools' predictive skill and an apportionment of the predictability between legacy effects and input forcing data. To this end, models were forced with two meteorological datasets from the European Centre for Medium-Range Weather Forecasts (ECMWF), the seasonal forecasting system, SEAS5, with 3-month lead times and the ERA5 reanalysis. Historical skill was assessed by comparing both model outputs, i.e. seasonal lake hindcasts (forced with SEAS5), and pseudo-observations (forced with ERA5). The skill of the seasonal lake hindcasts was generally low although higher than the reference hindcasts, i.e. pseudo-observations, at some sites for certain combinations of season and variable. The SEAS5 meteorological predictions showed less skill than the lake hindcasts. In fact, skilful lake hindcasts identified for selected seasons and variables were not always synchronous with skilful SEAS5 meteorological hindcasts, raising questions on the source of the predictability. A set of sensitivity analyses showed that most of the forecasting skill originates from legacy effects, although during winter and spring in Norway some skill was coming from SEAS5 over the 3-month target season. When SEAS5 hindcasts were skilful, additional predictive skill originates from the interaction between legacy and SEAS5 skill. We conclude that lake forecasts forced with an ensemble of boundary conditions resampled from historical meteorology are currently likely to yield higher-quality forecasts in most cases.publishedVersio

Mineralization of organic matter in boreal lake sediments: rates, pathways, and nature of the fermenting substrates

The complexity of organic matter (OM) degradation mechanisms represents a significant challenge for developing biogeochemical models to quantify the role of aquatic sediments in the climate system. The common representation of OM by carbohydrates formulated as CH2O in models comes with the assumption that its degradation by fermentation produces equimolar amounts of methane (CH4) and dissolved inorganic carbon (DIC). To test the validity of this assumption, we modelled using reaction-transport equation vertical profiles of the concentration and isotopic composition (δ13C) of CH4 and DIC in the top 25 cm of the sediment column from two lake basins, one whose hypolimnion is perennially oxygenated and one with seasonal anoxia. Furthermore, we modelled solute porewater profiles reported in the literature for four other seasonally anoxic lake basins. A total of 17 independent porewater datasets are analyzed. CH4 and DIC production rates associated with methanogenesis at the five seasonally anoxic sites collectively show that the fermenting OM has a mean (± SD) carbon oxidation state (COS) value of −1.4±0.3 . This value is much lower than the value of zero expected from carbohydrate fermentation. We conclude that carbohydrates do not adequately represent the fermenting OM in hypolimnetic sediments and propose to include the COS in the formulation of OM fermentation in models applied to lake sediments to better quantify sediment CH4 outflux. This study highlights the potential of mass balancing the products of OM mineralization to characterize labile substrates undergoing fermentation in sediments.publishedVersio

Critical loads and the MAGIC model. Evaluating the country-scale applications in Norway using data from the 2019 national lake survey

Project Manager Kari AustnesThe critical loads methodology used at the national scale in Norway and the MAGIC model as applied to the lakes in the national 1000-lake survey have been evaluated, making use of the data from the 2019 national lake survey. For the acid-sensitive lakes in southern/middle Norway the MAGIC simulations based on data from the 1995 survey gave an acceptable prognosis for the lakewater chemistry measured in the 2019 resurvey. Several potential improvements are suggested for a re-calibration of MAGIC using the 2019 data, including two-point calibration. This can be used to evaluate scenarios of changed acid deposition in concert with other environmental drivers, such as climate change and altered forestry practices. The future role of N deposition is of special interest. Most lakes in the areas with critical load exceedance were not acidified. Several possible explanations for this are given. Testing various alternative values for inputs and parameters in the critical loads and exceedance calculations showed that certain combinations of changes could have marked effects on the critical load exceedance. Two approaches to updating the critical loads are suggested: 1) Calculate critical loads for the 1000 lakes and transfer the results to the national grid. 2) Keep the current setup but updating some of the inputs. Independent of choosing 1) or 2), the FAB model parameters should be re-visited.publishedVersio

Assessment of risks to drinking water provision in Glitrevann from forest fertilization and harvesting

Forest fertilization is planned in the Glitre catchment, an important drinking water source for the Drammen region. In this report, we explore whether fertilization is likely to put drinking water provision in the catchment at risk over the short term, as well as longer-term risk associated with fertilization and forest harvesting. Overall, we find there is little risk of forest fertilization reducing the water quality in Glitrevann, provided the forest management plans provided by Statskog are followed, together with fertilization and harvesting best management practices (as outlined in the Norwegian PEFC Forest Standard). We recommend routine stream monitoring be carried out during and for several years after harvesting to screen for potential effects

Vurdering av risiko for drikkevannsforsyningen fra Glitrevann knyttet til skoggjødsling og hogst

Prosjektleder Øyvind KasteForest fertilization is planned in the Glitre catchment, an important drinking water source for the Drammen region. In this report, we explore whether fertilization is likely to put drinking water provision in the catchment at risk over the short term, as well as longer-term risk associated with fertilization and forest harvesting. Overall, we find there is little risk of forest fertilization reducing the water quality in Glitrevann, provided the forest management plans provided by Statskog are followed, together with fertilization and harvesting best management practices (as outlined in the Norwegian PEFC Forest Standard). We recommend routine stream monitoring be carried out during and for several years after harvesting to screen for potential effects.The Research Council of NorwaypublishedVersio

Bypass of Booming Inputs of Urban and Sludge-Derived Microplastics in a Large Nordic Lake

Microplastic research, initially focusing on marine environments, left freshwater ecosystems largely unexplored. Freshwaters are also vulnerable to microplastics and are likely the largest microplastic supplier to the ocean. However, microplastic sources, transport pathways, and fluxes at the catchment level remain to be quantified, compromising efficient actions toward mitigation and remediation. Here we show that 70–90% of microplastics reaching Norway’s largest lake, originating primarily from urban waste mismanagement and sludge application on crops, continue their journey toward the ocean without being buried. Indeed, our microplastic budget for the catchment shows that out of the 35.9 tons (7.4–119.4 t) of microplastics annually released into the lake, only 3.5 tons (1.3–8.8 t) are settling to the lake bottom. The spatial and vertical microplastic distribution and diversity in lake sediments, the socio-economic modeling of plastic fluxes and spatial information on land use and potential plastic sources all point toward urban and agricultural areas as emission hotspots of increasing importance. We conclude that the degree to which lake sediments represent a net microplastic sink is likely influenced by the nature of microplastics the lake receives, and ultimately on their origin.publishedVersio

Bypass of Booming Inputs of Urban and Sludge-Derived Microplastics in a Large Nordic Lake

Microplastic research, initially focusing on marine environments, left freshwater ecosystems largely unexplored. Freshwaters are also vulnerable to microplastics and are likely the largest microplastic supplier to the ocean. However, microplastic sources, transport pathways, and fluxes at the catchment level remain to be quantified, compromising efficient actions toward mitigation and remediation. Here we show that 70–90% of microplastics reaching Norway’s largest lake, originating primarily from urban waste mismanagement and sludge application on crops, continue their journey toward the ocean without being buried. Indeed, our microplastic budget for the catchment shows that out of the 35.9 tons (7.4–119.4 t) of microplastics annually released into the lake, only 3.5 tons (1.3–8.8 t) are settling to the lake bottom. The spatial and vertical microplastic distribution and diversity in lake sediments, the socio-economic modeling of plastic fluxes and spatial information on land use and potential plastic sources all point toward urban and agricultural areas as emission hotspots of increasing importance. We conclude that the degree to which lake sediments represent a net microplastic sink is likely influenced by the nature of microplastics the lake receives, and ultimately on their origin.publishedVersio

Modelled Nitrosamine and Nitramine concentrations in Lake Elvåga following amine-based CO2 Capture at FOV Waste Incineration Plant at Klemetsrud

Future levels of the carcinogenic- and potentially carcinogenic nitrosamines (NSAs) and nitramines (NAs), respectively, were modelled in the drinking water source, Lake Elvåga following the planned full-scale amine-based CO2 capture at the Oslo waste incineration plant. A high-resolution and dynamic catchment model (INCA-Contaminants) was combined with a lake model add-on. NSA and NA deposition rates (provided from COWI/Norsk Energi/CERC) were combined with site specific information (hydrology and climate), and literature values of NSA and NA bio- and photodegradation rates and physiochemical parameters. The three scenarios, “best”, “likely”, and “worst” cases were created to capture the uncertainty of key parameters. Three years of full-scale CO2 capture resulted in maximum annual average sums of NSAs and NAs in the lake water at 0.24, 3.3, and 4.4 ng L-1, for the three scenarios, respectively. For the NSAs, photodegradation was an efficient depletion pathway, nearly balancing out the input rates. Lake water levels of NAs increased with time due to the lack of an efficient depletion pathway. Seasonal variation was evident in both the NSA and NA concentrations and this should be considered for potential future monitoring programs