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A global database of dissolved organic matter (DOM) concentration measurements in coastal waters (CoastDOM v1)
Christian Lønborg, Cátia Carreira, Gwenaël Abril, Katja Klun, Tinkara Tinta, 2024, izvirni znanstveni članek

Povzetek: Measurements of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP) concentrations are used to characterize the dissolved organic matter (DOM) pool and are important components of biogeochemical cycling in the coastal ocean. Here, we present the first edition of a global database (CoastDOM v1; available at, Lønborg et al., 2023) compiling previously published and unpublished measurements of DOC, DON, and DOP in coastal waters. These data are complemented by hydrographic data such as temperature and salinity and, to the extent possible, other biogeochemical variables (e.g. chlorophyll a, inorganic nutrients) and the inorganic carbon system (e.g. dissolved inorganic carbon and total alkalinity). Overall, CoastDOM v1 includes observations of concentrations from all continents. However, most data were collected in the Northern Hemisphere, with a clear gap in DOM measurements from the Southern Hemisphere. The data included were collected from 1978 to 2022 and consist of 62 338 data points for DOC, 20 356 for DON, and 13 533 for DOP. The number of measurements decreases progressively in the sequence DOC > DON > DOP, reflecting both differences in the maturity of the analytical methods and the greater focus on carbon cycling by the aquatic science community. The global database shows that the average DOC concentration in coastal waters (average ± standard deviation (SD): 182±314 µmolC L−1; median: 103 µmolC L−1) is 13-fold higher than the average coastal DON concentration (13.6 ± 30.4 µmol N L−1; median: 8.0 µmol N L−1), which is itself 39-fold higher than the average coastal DOP concentration (0.34 ± 1.11 µmol P L−1; median: 0.18 µmol P L−1). This dataset will be useful for identifying global spatial and temporal patterns in DOM and will help facilitate the reuse of DOC, DON, and DOP data in studies aimed at better characterizing local biogeochemical processes; closing nutrient budgets; estimating carbon, nitrogen, and phosphorous pools; and establishing a baseline for modelling future changes in coastal waters.
Ključne besede: global database, dissolved organic matter, coastal waters, marine biology
Objavljeno v DiRROS: 17.05.2024; Ogledov: 64; Prenosov: 151
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Diketopyrrolopyrrole pigment core@multi-layer ▫$SiO_2$▫ shell with improved photochemical stability
Erika Švara Fabjan, Zineb Saghi, Paul A. Midgley, Mojca Otoničar, Goran Dražić, Miran Gaberšček, Andrijana Sever Škapin, 2018, izvirni znanstveni članek

Povzetek: A model organic pigment (diketopyrrolopyrrole) is encapsulated by a silica coating in order to improve its photochemical stability. Unlike in previous works where single-layer silica coatings were used for similar purposes, we here propose creation of a multi-layer silica shell synthesized via in-situ sol-gel method, which should significantly improve the homogeneity and thus the protection ability of the coating. This is done by repeating the basic two-step process (pigment surface modification and silica encapsulation) several times, creating the final protective shell in a layer-by-layer fashion. The compositional and structural properties of the prepared coatings is studied using Fourier-transform infrared spectroscopy, differential thermal and thermogravimetric analysis, nitrogen adsorption measurements and transmission electron microscopy. Photochemical stability of non-encapsulated and encapsulated pigment particles is evaluated via the so-called fast-irradiation method. Various correlations between the essential coating properties, such as thickness, porosity, SiO2 content, and the corresponding photochemical stability of the samples are established and discussed in detail. As a whole, our results confirm the basic hypothesis, that multiple-layered silica shells show improved pigment protection ability in comparison to the single-layer coatings.
Ključne besede: organic pigments, silica coating, encapsulation, morphology, photocemical stability
Objavljeno v DiRROS: 27.03.2024; Ogledov: 159; Prenosov: 60
.pdf Celotno besedilo (1,78 MB)
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Waste rubber incorporated in the alkali-activated metakaolin’s aluminosilicate network enhanced by microwave irradiation
Barbara Horvat, Branka Mušič, 2024, objavljeni znanstveni prispevek na konferenci

Povzetek: Building materials represent the possibility of prolonging the life of waste materials. The key is to ensure that the products are suitable for their function. So we activated metakaolin with the alkaline Na-silicate solution in the ratio that ensures the prevention of efflorescence and high mechanical strength (Horvat and Ducman, 2019). As the waste material (to be incorporated in the aluminosilicate network (ASN) of the alkali-activated metakaolin) ground waste rubber from electric cables was used in the preselected mass ratios. Its inclusion in products, like paving stones, can reduce stiffness, improve durability, dampen vibrations, and reduce road noise. The mechanical strengths of test samples with rubber present on the active surface or slightly below were higher compared to samples where rubber was encapsulated throughout the volume. Compressive strength was higher when samples were irradiated with low powers of microwaves while irradiation with higher powers led to the foaming of alkali-activated slurry. The encapsulation quality of the ground rubber was evaluated by SEM while the chemical influence on ASN was determined by EDS, FTIR, and XRD. Slipperiness change on the active surface of pavement stones proved that the addition of the ground rubber enhanced the walking safety of the product.
Ključne besede: secondary raw material, alkali activated material, waste rubber, metakaolin, encapsulation of organic in inorganic material, microwave irradiation, mechanical strength
Objavljeno v DiRROS: 12.03.2024; Ogledov: 352; Prenosov: 353
.pdf Celotno besedilo (13,99 MB)
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Bio-solution for global sand crisis and sustainable organic agriculture in desert states
Darina Štyriaková, Iveta Štyriakova, Jaroslav Šuba, Felix Föhre, 2022, objavljeni znanstveni prispevek na konferenci

Povzetek: Sand is an important component of many everyday items, and currently sand is the second most extracted resource on earth after water, but it is not sustainable: we are running out of sand! The black market is booming, and the sand mafia is mining sand at any price. Desert sand is unusable, even Dubai must import it. The smooth surface and iron impurities prevent its industrial use. In this study, bacteria in the bioleaching test attacked the surface of the mineral grains and dissolved impurities including iron through organic acids. Furthermore, the liquid residue containing dissolved iron, organic acids and bacteria stimulated the growth plant what can be a valuable biofertilizer and biostimulant for organic agriculture. Desert states have fertility problems. Despite this, Qatar, for example, is aiming for self-sufficiency in vegetables “in five years”. Results showed that bioleaching combined with magnetic separation resulted in iron removal of 73.23%. The sand after treatment can be suitable to produce clear flat glass, coloured container glass, insulating glass fibres or ceramics. The integrated technology based ecological study revealed overall as utilization potential of the desert sand and the liquid residue could support glass and food production in desert states.
Ključne besede: materials, sand, bioleaching, sustainable organic agriculture, desert states
Objavljeno v DiRROS: 31.01.2024; Ogledov: 215; Prenosov: 128
.pdf Celotno besedilo (443,33 KB)
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Soil organic carbon stock capacity in karst dolines under different land uses
Mateja Breg Valjavec, Andraž Čarni, Daniel Žlindra, Matija Zorn, Aleksander Marinšek, 2022, izvirni znanstveni članek

Povzetek: The soil organic carbon (SOC) was determined in soils of enclosed karst depressions (dolines) (NW Dinaric Mts.) to define their potential for organic carbon sequestration. SOC was measured in the forest, succession (scrubland), and grassland plots at the bottom of dolines at four depths (0–40 cm) and for 40 cm soil layer SOC stock was calculated. We demonstrated that the prevailing fine soil fractions, the C/N ratio and soil thickness play a positive role in the storage capacity of SOC in dolines regardless land use type. Grasslands have the lowest SOC storage capacity (106 t/ha/40 cm), while the highest SOC storage capacity is in succession plots (130 t/ha/40 cm). The last are covered by shrub communities dominated by Prunus spinosa, forming dense communities, and are typical of abandoned croplands or meadows that have been impacted by high levels of nutrients during cultivation phase. At this stage, there is no additional nutrient input in studied plots, which lowers the nutrient content and increases the C/N ratio. C/N ratio is the highest in the forest, where SOC stock capacity is 116 t/ha/40 cm. Given the trend towards the abandonment of agricultural land at Kras Plateau (SW Slovenia), we can expect more overgrowth of dolines, and thus an increase in carbon stocks and stabilization of organic carbon in forest soils. In contrary, we noticed the alarming decrease in grasslands and increase in urban land. The SOC storage in 2020 was for 12,538 t/ha/40 cm lower than in 2002. Although grasslands showed the lowest SOC storage, their contribution to total SOC storage in dolines is very important. Since there is a lack of studies on carbon stocks in doline soils, our research is of great importance and a novelty and gives an important background for further research on SOC stock in karst landscapes worldwide.
Ključne besede: organic carbon sequestration, karst, grassland, forests, scrubland, dolines
Objavljeno v DiRROS: 20.04.2023; Ogledov: 410; Prenosov: 261
.pdf Celotno besedilo (6,74 MB)
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Control of organic contaminants in groundwater by passive sampling and multivariate statistical analysis
Anja Koroša, Nina Mali, 2022, izvirni znanstveni članek

Povzetek: Organic contaminants in groundwater are among the most challenging chemical compound contaminants today, particularly when it comes to understanding their occurrence, origin, and relations in groundwater, as well as the transport processes, fate, and environmental impacts involved. This paper presents the use of active carbon fibre (AFC) passive sampling and multivariate statistical processing of the results to predict the possible occurrence of organic compounds (OCs) in groundwater and to determine the origin of various anthropogenic activity. This study aims to deepen our knowledge on the control of OCs in groundwater by introducing a multi-analytical and multielemental holistic approach, using the Dravsko polje aquifer, the largest intergranular aquifer in Slovenia, as an example.
Ključne besede: compounds of concern, groundwater contaminants, organic compounds, passive sampling
Objavljeno v DiRROS: 22.06.2022; Ogledov: 629; Prenosov: 243
.pdf Celotno besedilo (11,61 MB)

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