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Iskalni niz: "ključne besede" (carbon) .

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Silver particle-decorated carbon paste electrode based on ionic liquid for improved determination of nitrite
Samo B. Hočevar, Vasko Jovanovski, Eva Menart, 2015

Povzetek: A simple silver particle-modified carbon paste electrode is proposed for the determination of low concentration levels of nitrite ions. The electrode consists of a carbon powder decorated with silver sub-micrometre particles (AgPs) and a hydrophobic ionic liquid trihexyltetradecylphosphonium chloride as a binder. It has been shown that AgPs exhibit a strong electrocatalytic effect on the nitrite oxidation. For optimal electroanalytical performance the electrode was conditioned via silver oxidation/reduction cycle. The electrode revealed a linear square-wave voltammetric response in a wide examined concentration range of 0.05 to 1.0 mmol L− 1, limit of detection (LOD) of 3 μmol L− 1 and excellent repeatability with RSD of 0.3%.
Ključne besede: Silver particles, Square-wave voltammetry, Nitrite, Ionic liquid, Carbon paste electrode
DiRROS - Objavljeno: 16.02.2015; Ogledov: 3848; Prenosov: 321

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Harvesting intensity and tree species affect soil respiration in uneven-aged Dinaric forest stands
Matjaž Čater, Eva Dařenová, Primož Simončič, 2021

Povzetek: Forest management, especially thinning and harvesting measures, has a significant impact on the forest carbon balance especially in the forests with long-term continuous cover history. We measured soil CO2 efflux (Rs) in three forest complexes of mixed, uneven-aged Dinaric forests with predominating silver fir (Abies alba Mill.), beech (Fagus sylvatica L.), and Norway spruce (Picea abies Karst.). Rs was measured after removal of mature forest stands with 50% and 100% intensity of living stock and compared with Rs on the control plots without any applied silvicultural measures. Rs was measured monthly in three consecutive 2012, 2013 and 2014 growing periods. Soil CO2 efflux increased after harvest of both intensities in all studied forest stands. The biggest increase was measured in beech stands and amounted up to 47 and 69% for 50% and 100% harvest intensities, respectively. The effect of harvest on Rs in spruce and fir stands was similar - up to 26% for 50% harvest intensity and 48% for 100% harvest intensity. Despite the biggest increase after harvest, Rs in beech stands returned the fastest to the level of the uncut forest and this levelling period (LP) took 14-17 months with a little delay of the stands with 100% harvest intensity. The LP for all fir stands, for spruce stands with 50% harvest intensity and for one spruce stand with 100% harvest intensity, was 26-29 months. At two spruce stands with 100% harvest intensity we did not record Rs levelling during our three-year study. This study involved forest stands of three predominating tree species growing under the same conditions, which allowed us to determine the species-specific sensitivity of soil CO2 efflux to the different harvesting intensities.
Ključne besede: harvesting intensity, soil CO2 efflux, silviculture, carbon release, silver fir forests, Beech forestrs, Norway spruce forests
DiRROS - Objavljeno: 08.10.2020; Ogledov: 751; Prenosov: 277
URL Celotno besedilo (0,00 KB)
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Short-term impacts of harvesting intensity on the upper soil layers in high karst Dinaric fir-beech forests
Emira Hukić, Matjaž Čater, Aleksander Marinšek, Mitja Ferlan, Milan Kobal, Daniel Žlindra, Hamid Čustović, Primož Simončič, 2021

Povzetek: The present study addresses the short-term effects of different harvest intensities under close-to-nature selective management on the upper soil layers in Slovenian and Bosnian Dinaric karst fir-beech forests. The different harvest intensities coincided with the single-tree and irregular shelterwood management, common in the region. The effect of harvesting intensity on the upper soil layers (Ol, Of, Ol and 0%10 cm mineral soil) was investigated by a repeated measurements experiment in Slovenia on 27 research plots in close-to nature managed forests. The properties of the upper layers (concentration of SOC and TN, C/N ratio, weights, BD and SOC stocks) were analyzed twice, before (2011) and after (2014) treatment of 50% and 100% harvest intensity in relation to the total standing growing stock of trees. As a control, we used no-treatment <20% harvesting intensity plots. To extend this experiment, we added three comparable plots from the Bosnian site: one in an old-growth forest with 0% harvest intensity and two in the managed forest with <20% harvest intensity. The results of the assessment of mean differences indicated a significant influence of harvesting intensity on the decrease in SOC, TN concentrations, weights and SOC stocks in the organic layers and the increase in BD and SOC stocks in the 0%10 cm mineral soil. The highest relative decreases in Ol, Of and Oh SOC stocks occurred in 50% (%10 and %38%) and 100% (%16 and %49%) harvest intensities. Negligible relative differences in both organic and 0%10 cm mineral layers were found for the <20% harvest intensity in the region. The change in forest light conditions resulting from differences in canopy openness as a function of applied harvest intensity explained the significant difference in the properties of the upper soil layers. The impact of the short-term losses in SOC stocks, in terms of overall soil productivity, may depend on the regeneration dynamics and melioration methods.
Ključne besede: close-to-nature forest management, harvest intensity, Calcic Cambisol, forest soil, soil organic carbon
DiRROS - Objavljeno: 10.05.2021; Ogledov: 501; Prenosov: 294
.pdf Celotno besedilo (18,42 MB)

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Empirical vs. light-use efficiency modelling for estimating carbon fluxes in a mid-succession ecosystem developed on abandoned karst grassland
Koffi Dodji Noumonvi, Mitja Ferlan, 2020

Povzetek: Karst systems represent an important carbon sink worldwide. However, several phenomena such as the CO2 degassing and the exchange of cave air return a considerable amount of CO2 to the atmosphere. It is therefore of paramount importance to understand the contribution of the ecosystem to the carbon budget of karst areas. In this study conducted in a mid-succession ecosystem developed on abandoned karst grassland, two types of model were assessed, estimating the gross primary production (GPP) or the net ecosystem exchange (NEE) based on seven years of eddy covariance data (2013%2019): (1) a quadratic vegetation index-based empirical model with five alternative vegetation indices as proxies of GPP and NEE, and (2) the vegetation photosynthesis model (VPM) which is a light use efficiency model to estimate only GPP. The Enhanced Vegetation Index (EVI) was the best proxy for NEE whereas SAVI performed very similarly to EVI in the case of GPP in the empirical model setting. The empirical model performed better than the VPM model which tended to underestimate GPP. Therefore, for this ecosystem, we suggest the use of the empirical model provided that the quadratic relationship observed persists. However, the VPM model would be a good alternative under a changing climate, as it is rooted in the understanding of the photosynthesis process, if the scalars it involves could be improved to better estimate GPP.
Ključne besede: eddy covariance, carbon flux, GPP, NEE, vegetation indices, remote sensing, satellite data, GPP map
DiRROS - Objavljeno: 03.01.2022; Ogledov: 154; Prenosov: 112
.pdf Celotno besedilo (3,07 MB)

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Chemical and isotopic composition of CO2-rich magnesium- sodium-bicarbonate-sulphate-type mineral waters from volcanoclastic aquifer in Rogaška Slatina, Slovenia
Teodóra Szőcs, Andrej Lapanje, László Palcsu, Nina Rman

Povzetek: Bottled natural mineral waters from an andesitic aquifer in Slovenia are enriched in magnesium (1.1 g/l), sulphate (2.2 g/l) and dissolved inorganic carbon (204 g/l). We analysed major ions, trace elements, tritium activity, 14 C, d18 OH2O , d2 HH2O, d13 CDIC, gas composition and noble gases in six wells. In addition, 87 Sr/ /86 Sr, d34 SSO4 and d11 B were analysed here for the first time. Stable isotopes with d18 O = -11.97 to -10.30% and d2 H = -77.3 to -63.8 confirm meteoric origin. CO2 degassing is evident at three wells, causing the oxygen shift of about -1.3%. Tritium activity was detectable only in the shallowest well, where the freshwater component was dated to the 1960s. d13 CDIC in five waters is -1.78 to ? 1.33%, typical of carbonate dissolution. Radiocarbon is low, 1.03–5.16 pMC. Chemical correction with bicarbonate concentration and d13 C correction methods gave best mean residence times, slightly longer than previously published. Sulphate has d34 S 26.6–28.9% and d18 O 8.9–11.1% due to dissolution of evaporites in carbonate rocks. Boron at concentrations of 1.2–6.1 mg/l has two origins: d11 B = 11.3–16.4% from hydrothermal alteration and d11 B = 26.6–31.7% from carbonate dissolution. Strontium at concentrations of 0.5–22.0 mg/l has 87 Sr/ /86 Sr, indicating three sources: 0.7106 for Miocene clastic rocks, 0.7082 for Triassic carbonates and 0.7070 for Lower Oligocene andesitic rocks. CO 2 represents the majority of the dissolved ([ 98.84 vol%) and separated gas ([ 95.23 vol%). Methane is only found in two wells with a max. of 0.30 vol%. All waters show excess helium and 16–97% of mantlederived helium. Since all show subsurface degassing, the paleo-infiltration temperature could not be calculated.
Ključne besede: natural tracers, carbon, sulphur, strontium and boron isotopes, noble gases
DiRROS - Objavljeno: 24.03.2022; Ogledov: 112; Prenosov: 49
.pdf Celotno besedilo (3,10 MB)

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