Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2023
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Franziska Fischer Marianne Bechmann Hans Olav Eggestad Sigrun Hjalmarsdottir Kværnø Jian LiuAbstract
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Livestock husbandry has raised enormous environmental concerns around the world, including water quality issues. Yet there is a need to document long-term water quality trends in livestock-intensive regions and reveal the drivers for the trends based on detailed catchment monitoring. Here, we assessed the concentration and load trends of dissolved reactive phosphorus (DRP) in streamwater of a livestock-intensive catchment in southwestern Norway, based on continuous flow measurements and flow-proportional composite water sampling. Precipitation and catchment-level soil P balance were monitored to examine the drivers. At the field level, moreover, the relationship between soil P balance and soil test P (measured using the ammonium lactate extraction method, P-AL) was assessed. Results showed that on average of 20 years 95 % of the P was applied to the catchment during March–August, when 40 % of annual precipitation and 25 % of annual discharge occurred. The low runoff helped reduce P loss following P applications. However, flow-weighted annual mean DRP concentration significantly increased with increasingly cumulative soil P surplus (R2 = 0.55, p = 0.0002). With a mean annual P surplus of 8.8 kg ha−1, the annual mean DRP concentration (range: 49–140 μg L−1; mean: 80 μg L−1) and annual DRP load (range: 0.35–1.46 kg ha−1; mean: 0.65 kg ha−1) significantly increased over the 20-year monitoring period (p = 0.001 and 0.0003, respectively). At the field level, P-AL concentrations were positively correlated with soil P balances (R2 = 0.48, p < 0.0001), confirming the long-term impact of P balances on the risks of P loss. The study highlights the predominant role of long-term P balances in affecting DRP loss in livestock-intensive regions through the effect on soil test P.
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Constructed wetlands (CWs) are a widely recognised measure for reducing pollution loads and improving the quality of surface waters. The removal efficiency of CWs varies considerably depending on system type and design as well as residence time, hydraulic load, particles and nutrient loading rates. Therefore, there is a need to closely monitor the efficiency of existing measures, look at their efficiency in practice and be able to foresee potential implications for their efficiency in light of climate change and land management intensification. This study presents 18 years of data from a typical Norwegian small CW established in the Skuterud catchment. The main objective of this study was to look at the impact of hydraulic load, particles and nutrient loads (depending on climatic factors such as temperature and precipitation) on CW effectiveness. The results showed an average of 39 % and 22 % annual removal efficiency for sediment and phosphorus, respectively. It appears that good CW effectiveness coincides with a combination of high sediment or phosphorus loads to the CW and a stable runoff of low to moderate intensity. At the seasonal level, the highest sediment and phosphorus removal efficiency is observed in the summer seasons (47% for sediment and 29% for phosphorus), when the sediment and phosphorus loads and runoff are at their lowest, and the lowest in autumn (23% for sediment) and in winter (4% for phosphorus). The relationship between removal efficiency and loads to the CW is not that straightforward, as other seasonal differences, such as erosion patterns, vegetation development, also become important. The conclusion based on the results presented is that establishing CWs can be a good supplement to best management practice in erosion-prone catchments with sensitive recipients.
Authors
Csilla Farkas Moritz Shore Gökhan Cüceloglu Levente Czelnai Attila Nemes Brigitta Szabó Natalja Čerkasova Rasa Idzelyté Sinja WeilandAbstract
The H2020 OPTAIN project involves both, catchment-, and field-scale modelling of the transport of water and nutrients. The catchment-scale modelling is performed at fourteen case study catchments across Europe using the SWAT+ model. At seven OPTAIN case studies, field-scale modelling is applied using the SWAP model. The aim of the SWAP modelling is to provide data on soil water balance elements using a more detailed (at field-scale) soil hydrological model and to cross-validate this data with the relevant fields in SWAT+. As the official manual from the SWAP model developers is rather detailed and complex, the OPTAIN SWAP modelling protocol focuses on practical issues, without overwhelming the modellers with information unnecessary for their case-studies. It also describes new tools, such as rswap, developed within the OPTAIN project for reference data quality check, model calibration and visualisation of the model results.