THE EVALUATION OF STABLE ISOTOPIC RATIOS 13C AND 15N IN HUMIC ACIDS ALONG A FEN PEAT PROFILE

Mires are known as consistent environmental archives, but humic acids are the fraction of peat that is most recalcitrant and refractory to organic matter degradation, thus data on environmental changes during mire development can be recorded into them. This work was focused on the studies of stable isotopic ratios delta carbon-13 and delta nitrogen-15, and their distribution in humic acids within fen peat layers of different depths and peat composition. The variations in delta carbon-13 reflect isotopic variations in peat-forming plants over time and can be considered as a function of photosynthetic pathway that is being used to fix carbon dioxide. At the same time, variations in delta nitrogen-15 show nitrogen fixation in peat-forming plants and can be traced along with peat decomposition degree and depth. Properties of humic acids were studied in 2018 at 3 fens located in Latvia and Southern Finland, and comparatively they show properties. The method used for the determination of stable isotopes was the isotope-ratio mass spectrometry that was performed in the Faculty of Chemistry, University of Latvia. Results on delta carbon-13 indicate signal of C3 peat-forming plants, while signal of C4 peat-forming plants is not evident, which can be explained by non-efficient carbon dioxide fixation in fen vegetation. Results on delta nitrogen-15 show variations in nitrogen fixation in fen vegetation. Data show nitrogen fixation in terrestrial plants, however significant shifts in absolute isotope values indicate dependence on variations in peat decomposition degree and botanical composition. Data suggest that differences in peat botanical composition, decomposition degree and site dependent characteristics reflect in differences in delta carbon-13 and delta nitrogen-15 variation

Electro-catalytic and photo-catalytic reformation of CO2–reactions and efficiencies processes (Review)

Energy harvesting with lowest environmental impact is one of key elements for cleaner future. Photocatalytic as well as electrocatalytic CO2 reformation processes are considered as prominent methods. Thus, extensive research of CO2 reformation is being done to find the right materials that holds crucial qualities. For photocatalysis that includes pronounced separation of light-generated opposite sign charge carriers, sensitivity to visible light, high quantum yield. In electrocatalysis high CO2 adsorption, chemical stability, multielectron reaction catalysts are necessary. Additionally, materials participating in the reaction process must be provided with charge carriers at proper reduction and oxidation potentials. To meet the set goal of lowering environmental impact and lower CO2 amounts exhausted into the atmosphere by human activities, it is necessary to find right technology for capturing, storing, and reusing carbon dioxide. Various technologies and materials in different levels of readiness are available and under development, such as CuO loaded TiO2 nanotubes for photocatalytic reformation or electrocatalytic reduction on copper. Not only the proof of concept is necessary but estimation and more importantly determination of the efficiency of both electro and photo catalytic reformation of CO2. In this work review of reactions and efficiency of both processes based on existing established technological methods is done.Horizon 2020 Research and Innovation Program 768789; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Telpas norobežojošo konstrukciju materiālu ietekme uz mikroklimata stabilizāciju

Nekustamā īpašuma vērtības kritērijiem ir patiesi jāatspoguļo nekustamā īpašuma spēju apmierināt visas sabiedrības vajadzības gan šodien, gan visā īpašuma eksistences dzīves ciklā. Ir nepieciešams adekvāti novērtēt likumsakarības, kuras nosaka telpas energopatēriņa un mikroklimata izmaiņu atkarību gan no iekštelpu ekspluatācijas mainīgā režīma, gan no apkārtējās vides mainīgo un dinamisko procesu ietekmes, gan no norobežojošo konstrukciju materiālu fizikālajām īpašībām. Tikai novērtējot visu faktoru dinamisko ietekmi, ir iespējams izveidot norobežojošo konstrukciju no vispiemērotākajiem materiāliem ar vispiemērotākajiem parametriem, lai sasniegtu mērķi – optimālu telpas mikroklimatu reizē ar vislielāko būves energoefektivitāti. Lai veiktu faktoru novērtējumu, materiālu optimizāciju, kā arī sagatavotu izziņas materiālu ēku projektēšanai, ir nepieciešams izstrādāt konkrētu multifizikālu dinamisko parametru skaitliskās analīzes modeli sistēmai: materiāls–termālā vide (ISO7330)–mikroklimats. Šāda materiālu īpašību ietekmes modelēšana un to struktūras optimizācija ļaus garantēt aktuālo būvniecības risinājumu konkurētspēju un nodrošinās šo konstrukciju ilgtspējīgu pielietojumu perspektīvā

Geografijas macibu satura izpete un izstrade atbilstosi videjas izglitibas programmu prasibam

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLEMinistry of Education and Science of the Republic of Latvia, Riga (Latvia)LVLatvi