• A carbon balance of Norway: terrestrial and aquatic carbon fluxes 

      de Wit, Heleen; Austnes, Kari; Hylen, Gro; Dalsgaard, Lise (Journal article; Peer reviewed, 2015)
      Northern landscapes accumulate carbon in vegetation and soils while rivers transport significant amounts of land-derived carbon to coastal areas. Here, we quantify carbon sources and sinks in main ecosystems (forests, ...
    • Atmospheric deposition and lateral transport of mercury in Norwegian drainage basins: A mercury budget for Norway 

      Braaten, Hans Fredrik Veiteberg; Gundersen, Cathrine Brecke; Sample, James Edward; Selvik, John Rune; de Wit, Heleen (NIVA-rapport;7310, Research report, 2018)
      Reduced atmospheric loading of mercury (Hg) can improve the environmental status of freshwaters and coastal ecosystems. Sparse data limit impact assessments of changes in atmospheric Hg on aquatic ecosystems. Here, a Hg ...
    • Biodiversity in freshwaters: temporal trends and response to water chemistry (ICP Waters report 114/2013) 

      Velle, Gaute; Telford, Richard J.; Curtis, Chris; Eriksson, Lars; Fjellheim, Arne; Frolova, Marina; Fölster, Jens; Grudule, Natalja; Halvorsen, Godtfred A.; Hildrew, Alan; Hoffmann, Andreas; Indriksone, Iveta; Kamasová, Lenka; Kopáèek, Jiøí; Orton, Stuart; Krám, Pavel; Monteith, Don T.; Senoo, Takaaki; Shilland, Ewan M.; Stuchlík, Evžen; Wiklund, Magda-Lena; de Wit, Heleen; Skjelkvaale, Brit Lisa (NIVA-rapport;6580, Research report, 2013-10)
      This report describes trends in biological diversity of benthic invertebrates from acid-sensitive lakes and rivers sampled between 1982 and 2011 in the Czech Republic, Germany, Latvia, Norway, Sweden and the UK. The results ...
    • Biodiversity of macro-invertebrates in acid-sensitive waters: trends and relations to water chemistry and climate. ICP Waters report 127/2016 

      Velle, Gaute; Mahlum, Shad; Monteith, Don T.; de Wit, Heleen; Arle, Jens; Eriksson, Lars; Fjellheim, Arne; Frolova, Marina; Fölster, Jens; Grudule, Natalja; Halvorsen, Godtfred A.; Hildrew, Alan; Hruška, Jakub; Indriksone, Iveta; Kamasová, Lenka; Kopáček, Jiří; Krám, Pavel; Orton, Stuart; Senoo, Takaaki; Shilland, Ewan M.; Stuchlík, Evžen; Telford, Richard J.; Ungermanová, Lenka; Wiklund, Magda-Lena; Wright, Richard F. (NIVA-rapport;7077, Research report, 2016-09)
      This is a study of the international impact of acid emission reductions on vulnerable freshwater biodiversity of benthic macroinvertebrates. In order to properly attribute impacts it is necessary to also incorporate the ...
    • Biological intercalibration: Invertebrates 1713 (ICP Waters report 118/2014) 

      Fjellheim, Arne; Johannessen, Arne; Landås, Torunn Svanevik; de Wit, Heleen (NIVA-rapport;6662, Research report, 2014-04)
      The 17th intercalibration of invertebrates in the ICP Waters programme had contribution from four laboratories. The laboratories identified a very high portion of the individuals in the test samples, usually > 95% of the ...
    • Biological intercalibration: Invertebrates 1814 

      Fjellheim, Arne; Johannessen, Arne; Landås, Torunn Svanevik (NIVA-rapport;6761, Research report, 2014)
      The 18th intercalibration of invertebrates in the ICP Waters programme had contribution from three laboratories. The laboratories identified a very high portion of the individuals in the test samples, > 95% of the total ...
    • Chemical and biological recovery in acid-sensitive waters: trends and prognosis (ICP Waters report 119/2015) 

      Garmo, Øyvind Aaberg; de Wit, Heleen; Fjellheim, A (NIVA-rapport;6847, Research report, 2015)
      We present a trend analysis of surface water chemistry in in acid-sensitive lakes and rivers in Europe and North America, for the period 2000 to 2011, combined with a prognosis for water chemistry in Europe in 2020. Also, ...
    • Climate warming feedback from mountain birch forest expansion: Reduced albedo dominates carbon uptake 

      de Wit, Heleen; Bryn, Anders; Hofgaard, Annika; Karstensen, Jonas; Kvalevåg, Maria Malene; Peters, Glen Philip (Journal article; Peer reviewed, 2013)
      Expanding high elevation and high latitude forest has contrasting climate feedbacks through carbon sequestration (cooling) and reduced surface reflectance (warming), which are yet poorly quantified. Here, we present an ...
    • Effects of sample preservation and storage on mercury speciation in natural stream water 

      Braaten, Hans Fredrik Veiteberg; de Wit, Heleen; Harman, Christopher Peter; Hageström, Ulla; Larssen, Thorjørn (Journal article; Peer reviewed, 2014)
      Despite an increasing focus on low level methods for determination of mercury species in water over the last decades, few studies have paid attention to direct effects of different sample preparation methods (i.e. preservation ...
    • Environmental factors influencing mercury speciation in Subarctic and Boreal lakes 

      Braaten, Hans Fredrik Veiteberg; de Wit, Heleen; Fjeld, Eirik; Rognerud, Sigurd; Lydersen, Espen; Larssen, Thorjørn (Journal article; Peer reviewed, 2014)
      Environmental drivers of total mercury (TotHg) concentrations, methylmercury (MeHg) concentrations, and MeHg fractions (a proxy for methylation potential, expressed as %MeHg) were assessed in a synoptic study of 51 lakes ...
    • Forest harvest effects on mercury in streams and biota in Norwegian boreal catchments 

      de Wit, Heleen; Granhus, Aksel; Lindholm, Markus; Kainz, Martin J.; Lin, Yan; Braaten, Hans Fredrik Veiteberg; Blaszczak, Joanna (Journal article; Peer reviewed, 2014)
      Forest harvesting practices can potentially increase mercury run-off from catchments. A paired catchment experiment was conducted in a boreal forest in southern Norway, to test effects of forest harvest operations on (i) ...
    • From greening to browning: Catchment vegetation development and reduced S-deposition promote organic carbon load on decadal time scales in Nordic lakes 

      Finstad, Anders Gravbrøt; Andersen, Tom; Larsen, Søren; Tominaga, Koji; Blumentrath, Stefan; de Wit, Heleen; Tømmervik, Hans; Hessen, Dag Olav (Journal article; Peer reviewed, 2016)
      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 ...
    • Mercury in fish from Norwegian lakes: The complex influence of aqueous organic carbon 

      Braaten, Hans Fredrik Veiteberg; de Wit, Heleen; Larssen, Thorjørn; Poste, Amanda (Journal article; Peer reviewed, 2018)
      Mercury (Hg) concentrations in water and biota are often positively correlated to organic matter (OM), typically measured as total or dissolved organic carbon (TOC/DOC). However, recent evidence suggests that higher OM ...
    • Natural organic matter fractions and their removal in full-scale drinking water treatment under cold climate conditions in Nordic capitals 

      Krzeminski, Pawel; Vogelsang, Christian; Meyn, Thomas; Köhler, Stephan; Poutanen, Heikki; de Wit, Heleen; Uhl, Wolfgang (Journal article; Peer reviewed, 2019)
      Drinking water treatment plants (DWTPs) designed to remove natural organic matter (NOM) are challenged as concentrations of NOM in raw waters are increasing. Here, we assess seasonal differences in NOM quality and quantity, ...
    • Overvåking av referanseelver 2017. Basisovervåking i henhold til vannforskriften 

      Moe, Therese Fosholt; Thrane, Jan-Erik; Persson, Jonas; Bækkelie, Knut Andreas Eikland; Myrvold, Knut Marius; Olstad, Kjetil; Garmo, Øyvind Aaberg; Grung, Merete; de Wit, Heleen (NIVA-rapport;7259, Research report, 2018)
      Overvåking av referanseelver startet opp i 2017, og 47 antatte referansevannforekomster ble undersøkt. Vannforekomstene dekket alle økoregioner og mange ulike elvetyper, men det er knyttet relativt stor usikkerhet til en ...
    • Overvåking av referanseelver 2017. Basisovervåking i henhold til vannforskriften 

      Moe, Therese Fosholt; Thrane, Jan-Erik; Bækkelie, Knut Andreas Eikland; Myrvold, Knut Marius; Olstad, Kjetil; Garmo, Øyvind Aaberg; Grung, Merete; de Wit, Heleen (NIVA-rapport;7259, Research report, 2018)
      Overvåking av referanseelver startet opp i 2017, og 47 antatte referansevannforekomster ble undersøkt. Vannforekomstene dekket alle økoregioner og mange ulike elvetyper, men det er knyttet relativt stor usikkerhet til en ...
    • Overvåking av referanseelver 2018. Basisovervåking i henhold til vannforskriften 

      Moe, Therese Fosholt; Persson, Jonas; Bækkelie, Knut Andreas Eikland; Myrvold, Knut Marius; Garmo, Øyvind Aaberg; Grung, Merete; Hindar, Atle; Guerrero Calidonio, Jose-Luis; de Wit, Heleen (NIVA-rapport;7378, Research report, 2019)
      Overvåking av referanseelver har vært gjennomført over to år, og i andre år (2018) ble 34 antatte referansevannforekomster undersøkt. Vannforekomstene dekket mange ulike elvetyper i økoregionene Finnmark, Vestlandet og ...
    • Oxygen dynamics in a boreal lake responds to long-term changes in climate, ice phenology, and DOC inputs 

      Couture, Raoul-Marie; de Wit, Heleen; Tominaga, Koji; Kiuru, Petri; Markelov, Igor (Journal article; Peer reviewed, 2015)
      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 ...
    • Proceedings of the 29th Task Force meeting of the ICP Waters Programme in Český Krumlov, Czech Republic 1st –3rd October, 2013 (ICP Waters report 117/2014) 

      de Wit, Heleen; Wathne, Bente Margrethe; Hruska, Jakub (NIVA-rapport; 6643, Research report, 2014-03)
      The report contains Proceedings of the 29th Task Force meeting of the ICP Waters Programme in Český Krumlov, Czech Republic, October 1 – 3, 2013, including national contributions from Armenia, Canada, the Czech Republic, ...
    • Proceedings of the 30th Task Force meeting of the ICP Waters Programme in Grimstad, Norway 14th –16th October, 2014 

      de Wit, Heleen; Wathne, Bente Margrethe; de Wit, Heleen (NIVA-rapport;6793, Research report, 2015)
      Proceedings of the 30th Task Force meeting of the ICP Waters Programme in Grimstad, Norway, October 14 – 16, 2014. National contributions from Russia, Finland, Canada, Sweden, and Norway.