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Sirvi Autor "Reitzel, Kasper" järgi

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  • Pisipilt
    Kirje
    Evaluation of dried amorphous ferric hydroxide CFH-12® as agent for binding bioavailable phosphorus in lake sediments
    (Elsevier, 2018) Fuchs, Elisabeth; Funes, Ana; Saar, Katrin; Reitzel, Kasper; Jensen, Henning S.; Centre for Limnology. Estonian University of Life Sciences
    Metal hydroxides formed from aluminum (Al) and iron (Fe) salts can be used as phosphorus (P) adsorbents in lake restoration, but the application entails problems in low-alkaline lakes due to acid producing hydrolysis and potential formation of toxic metal ions. Therefore, we tested the potential of applying CFH-12® (Kemira) – a dried, amorphous Fe-oxide with no pH effect – in lake restoration. Since Fe3+ may become reduced in lake sed- iments and release both Fe2+ and any associated P we also evaluated the redox sensitivity of CFH-12® in com- parison with freshly formed Fe(OH)3. CFH-12® was added to undisturbed sediment cores from three Danish lakes relative to the size of their mobile P pool (molar Fe:PMobile dose ratio of ~10:1), and P and Fe fluxes across the sediment-water interface were compared with those from untreated cores and cores treated with freshly formed Fe(OH)3. Under anoxic conditions, we found that CFH-12® significantly reduced the P efflux from the sediments (by 43% in Lake Sønderby, 70% in Lake Hampen and 60% in Lake Hostrup) while the Fe 2+ efflux remained unchanged relative to the untreated cores. Cores treated with freshly formed Fe(OH)3 retained more P, but released significantly more Fe 2+ , indicating continued Fe3+ reduction. Finally, experiments with pure phases showed that CFH-12® adsorbed less P than freshly formed Fe(OH)3 in the short term, but was capable of adsorbing up to 70% of P adsorbed by Fe(OH)3 over 3 months. With product costs only 30% higher than Al salts we find that CFH-12® has potential for use in restoration of low-alkaline lakes.
  • Pisipilt
    Kirje
    The impact of climate change and eutrophication on phosphorus forms in sediment: Results from a long-term lake mesocosm experiment
    (Elsevier, 2022) Saar, Katrin; Nõges, Peeter; Søndergaard, Martin; Jensen, Maria; Jørgensen, Charlotte; Reitzel, Kasper; Jeppesen, Erik; Lauridsen, Torben L.; Jensen, Henning S.; Centre for Limnology. Estonian University of Life Science
    Characteristics of bottom sediments in lake mesocosms 11 years after starting the experiment were studied in order to determine the effects of nutrient loading, temperature increase and vegetation type on concentration and vertical dis- tribution of phosphorus (P) forms. The experimental setup consisted of 24 outdoor flow-through mesocosms with two nutrient treatments – low (L) and high (H) and 3 temperature levels – ambient (T0), heated by 2–4 °C (T1) and 3–6 °C (T2) in four replicates. Thickness of the organic sediment was measured and the sediment analysed for dry weight, or- ganic matter, and P fractions (according to a sequential extraction scheme) and organic P compounds (by ³¹P nuclear magnetic resonance spectroscopy). Higher nutrient loading led to increased sediment accumulation and higher con- centration of total P and most P fractions, except P bound to aluminium and humic matter. The dominant vegetation type covaried with nutrient levels. Vertical gradients in Ca bound P and mobile P in low nutrient mesocosms was per- haps a result of P coprecipitation with calcite on macrophytes and P uptake by roots indicating that in macrophyte-rich lakes, plants can be important modifiers of early P diagenesis. Temperature alone did not significantly affect sediment accumulation rate but the interaction effect between nutrient and temperature treatments was significant. At high nu- trient loading, sediment thickness decreased with increasing temperature, but at low nutrient loading, it increased with warming. The effect of warming on sediment composition became obvious only in nutrient enriched mesocosms showing that eutrophication makes shallow lake ecosystems more susceptible to climate change.
  • Pisipilt
    Kirje
    Supplementary data to the article "The impact of climate change and eutrophication on phosphorus forms in sediment: Results from a long-term lake mesocosm experiment"
    (Estonian University of Life Sciences, 2022) Saar, Katrin; Nõges, Peeter; Søndergaard, Martin; Jensen, Maria; Jørgensen, Charlotte; Reitzel, Kasper; Jeppesen, Erik; Lauridsen, Torben L.; Jensen, Henning S.
    The supplementary material contains 7 tables and 2 figures.
  • Pisipilt
    Kirje
    Sustainable lake restoration: From challenges to solutions
    (Wiley, 2023) Tammeorg, Olga; Chorus, Ingrid; Spears, Bryan; Nõges, Peeter; Nürnberg, Gertrud K.; Tammeorg, Priit; Søndergaard, Martin; Jeppesen, Erik; Paerl, Hans; Huser, Brian; Horppila, Jukka; Jilbert, Tom; Budzyńska, Agnieszka; Dondajewska-Pielka, Renata; Gołdyn, Ryszard; Haasler, Sina; Hellsten, Seppo; Härkönen, Laura H.; Kiani, Mina; Kozak, Anna; Kotamäki, Niina; Kowalczewska-Madura, Katarzyna; Newell, Silvia; Nurminen, Leena; Nõges, Tiina; Reitzel, Kasper; Rosińska, Joanna; Ruuhijärvi, Jukka; Silvonen, Soila; Skov, Christian; Važić, Tamara; Ventelä, Anne-Mari; Waajen, Guido; Lürling, Miquel
    Sustainable management of lakes requires us to overcome ecological, economic, and social challenges. These challenges can be addressed by focus- ing on achieving ecological improvement within a multifaceted, co-beneficial context. In-lake restoration measures may promote more rapid ecosystem responses than is feasible with catchment measures alone, even if multiple interventions are needed. In particular, we identify restoration methods that support the overarching societal target of a circular economy through the use of nutrients, sediments, or biomass that are removed from a lake, in agricul- ture, as food, or for biogas production. In this emerging field of sustainable restoration techniques, we show examples, discuss benefits and pitfalls, and flag areas for further research and development. Each lake should be assessed individually to ensure that restoration approaches will effectively address lake-specific problems, do not harm the target lake or downstream ecosystems, are cost-effective, promote delivery of valuable ecosystem ser- vices, minimize conflicts in public interests, and eliminate the necessity for repeated interventions. Achieving optimal, sustainable results from lake res- toration relies on multidisciplinary research and close interactions between environmental, social, political, and economic sectors.