1,721,114 research outputs found
IL RECUPERO DI ENERGIA E DI RISORSE IDRICHE
No full textCON UN APPROCCIO “ZERO WASTE”, I PROGETTI NAUPLIUS E “CO2 RE-USE” CONDOTTI
DAL DIPARTIMENTO DI SCIENZE AGRARIE DELL’UNIVERSITÀ DI BOLOGNA E BIOTEC SYS,
DIMOSTRANO IL SUCCESSO DI TRATTAMENTI INNOVATIVI VOLTI AL RIUTILIZZO DI ENERGIA E
RISORSE IDRICHE DA REFLUI URBANI, ZOOTECNICI E DELLE AZIENDE AGRO-ENERGETICHE
Surface-Enhanced Raman Scattering and Fluorescence Spectroscopy on Silver Plasmonic Nanoparticles as Innovative Techniques to Study Humic Substances. In Humic Substances and Natural Organic Matter
No full textThe application of normal Raman spectroscopy is not able to characterize the soil humic substances (HS) structure due to the intense fluorescence emission, which overlaps the Raman bands. Nevertheless, surface-enhanced Raman scattering (SERS) spectroscopy, based on localized surface plasmon (LSP) in nanostructured metals, leads to a remarkable local electromagnetic field enhancement and to the fluorescence quenching via a charge-transfer mechanism. The SERS technique was thus applied to investigate the structure and conformational changing of HS. However, the fluorescence is not quenched if the distance between fluorophores and LPS is relatively far. An intensification of the fluorescence emission
through the surface-enhanced fluorescence (SEF) at optimal distance above 10–100 Å can be detected. At distances further than this value, SERS and SEF signals are simultaneously emitted and recorded for molecular species placed in the vicinity of metal nanoparticles. Since the average size of HS is larger than this value, the fluorophores included in the HS structure are valid candidates causing intense SEF plus SERS joint emission spectra, without the intrinsic quenching observed on a surface
Thermal analysis (TG-DTA) and isotopic characterization (13C and 15N) of humic acids from different origins. Applied Geochemistry
No full textThermal analyses (TG-DTA), elemental composition and isotope analyses (13C and 15N) were performed on humic acids (HA) from peats (P), leonardites (Le) and lignites (L), in order to investigate their structure and the changes taking place during the humification process. Thermal analyses showed structural differences between HA samples in relation to their coalification rank. In particular the lignite HA were characterized by a more stable chemical composition at high temperatures.
The delta 13C and delta 15N values can provide information on the biogeochemical processes involved in HA formation. In particular, peat HA were linked to anoxic environments that enable plant residues to persist in their structure. In contrast, leonardite and lignite HA formation seems to be governed by different biogeochemical processes from those responsible for peat diagenesis. However, the isotopic analyses did not provide any distinction between leonardite and lignite HA. On the basis of the data presented in this study, it may be concluded that TG-DTA and isotope ratio measurements are powerful tools for investigating the formation pathway of humic substances fro
Soil–root cross-talking: The role of humic substances
Full text linkThe biological activity of humic substances (HS) has been elucidated in the last 40 years. Growth enhancement from HS has been demonstrated in several plants in the laboratory and the field. Morphogenesis effects have also been investigated and include induction of lateral root formation and root hair initiation in intact plants and stimulation of root and shoot development in treated cell calluses. HS enhance nutrient use efficiency, aiding assimilation of both macro and microelements and promoting plant growth by the induction of carbon, nitrogen, and secondary metabolisms. The review aims are to 1) shed light on the mechanism by which plants “talk” with soil through humic substances 2) elucidate the plant responses to the stimulatory effects of HS, the regulatory circuits that allow plants to cope with humus, and the feedback between plant community structures, and 3) show (in light of recent debate about the alkaline extraction of soil humic substances) the plant capability to acquire biologically active substances from soil. It will be shown that plants modify soils, creating and maintaining favorable habitats for growth and survival. Therefore, organic substances exuded by roots are not a wasteful loss of carbon and energy. They represent an evolved strategy by which plants “talk” to the soil. The mobilization of bioactive organic/humic substances from bulk soil or bulk humus is critical to plant and soil healt
Effects of two Lignosulfonate-Humates on Zea mays L. Metabolism
No full textTwo lignosulfonate-humates (a and b), derived by an industrial process from lignin, were chemically characterized and their effects on maize plants in terms of growth, nitrogen metabolism and photosynthesis were investigated. The biological effects of lignosulfonate humates were compared with those induced by a humic acid extracted from leonardite in order to better understand the complexity of their biological effects.
Our results displayed that both lignosulfonate-humates (a and b) had a hormone-like activity and increased root and leaf growth. Moreover, all treatments increased the content of chlorophyll, glucose and fructose and enhanced the activity of Rubisco, glutamine-synthetase and glutamate-synthase. The observed intense biological activity indicated that lignosulfonate-humates and leonardite humic acid had a positive role on photosynthetic
process of maize plants. In the light of these results, lignosulfonate-humates may be used as biostimulants to increase crop yield
Prospecting algae and cyanobacteria as bioprotectans for plant disease control
No full textThe European Directive 2009/128 on sustainable use of pesticides promotes the use of alternative approaches
to synthetic products for plant disease control to reduce human, animals and environmental risks. Among
alternatives, natural products based on cyanobacteria and algae are gaining attention. Our studies demonstrated
that application of water extracts from Anabaena minutissima, Ecklonia maxima and Jania adhaerens
controlled powdery mildew caused by Podosphaera xanthii on cucumber detached cotyledons and seedlings
and induced the expression of PR genes related to plant-induced resistance. In addition, tomato seed treatment
with the same extracts increased germination, seedling dry weight, calibre, and reduced root rot caused by
Rhizoctonia solani on tomato plants. Seed treatment also increased chitinase activity and lignin compound
contents in tomato seedlings. A deeper investigation on the possible bioactive compounds of A. minutissima,
E. maxima and J. adhaerens, revealed the antifungal activity of polysaccharides against Botrytis cinerea, agent
of grey mould, in vitro and in vivo on strawberry fruits. Latest research pointed out that application of
phycobiliproteins from A. minutissima, Arthrospira platensis and Hydropuntia cornea on tomato fruits before
B. cinerea challenge reduced grey mould disease. In particular, FT-IR and FT-Raman spectroscopies have
shown that phycobiliproteins from A. minutissima preserved cutin and pectine structures of tomato fruit from
B. cinerea infection. In conclusion, our research demonstrate the potentialities of algae and cyanobacteria as a
bioprotectans for plant disease control
Determination of Water-extractable Organic Carbon Combining High-temperature Catalytic Combustion and VNIR Spectroscopy
No full textLand use affects the soil C sequestration in alpine environment, NE Italy
Full text linkSoil carbon sequestration is strongly affected by soil properties, climate, and anthropogenic activities. Assessing these drivers is key to understanding the effect of land use on soil organic matter stabilization. We evaluated land use and soil depth influencing patterns of soil organic matter stabilization in three types of soil profiles located under the same pedogenetic matrix and alpine conditions but with different vegetation cover. The stock in soil organic carbon in the mean 0–20 cm layer increased from prairie (31.9 t ha−1) to prairie in natural reforestation (42 t ha−1) to forest (120 t ha−1), corresponding to increments of 1.3-fold prairie, for prairie in natural reforestation, and of 3.8-fold prairie for forest. The forest showed the highest humic carbon (21.7 g kg−1), which was 2.8 times greater than the prairie in natural reforestation and 4 times higher than the prairie. 13C-NMR spectroscopic measurements suggested a different C pattern. The prairie in natural reforestation and the prairie were characterized by a higher content in O,N-alkyl C with respect to the forest. Alkyl C and aromatic C in the prairie in natural reforestation and prairie did not show relevant differences while they decreased with respect to the forest. Carboxyl and phenolic C groups were markedly higher in forest and prairie than prairie in natural reforestation. Alkyl C, carboxyl C, and phenolic C prevailed in the Ah horizons whereas aromatic C and O,N-alkyl C were dominant in the B horizons. Overall, the marked distribution of O,N-alkyl C and alkyl C in humic substances (HS) indicates a low degree of humification. Nevertheless, in forest, the relatively high presence of aromatic C designated HS endowed with a relatively high humification degree. Thus, our results might suggest that in the alpine environment of NE Italy differences in soil organic matter (SOM) stocks and characteristics are affected by land use and anthropic activities
Soil porosity in physically separated fractions and its role in SOC protection
No full textPurpose
Processes that lead to soil organic carbon (SOC) protection depend on both soil porosity and structure organization, as well as chemical and biological properties. In particular, the soil micro-nano porosity (<30 μm) regulates microorganism accessibility to the soil pore system and offers surfaces for organic carbon adsorption and intercalation into soil minerals. The aim of this work was to investigate how pore size distribution can selectively protect specific carbon pools in different aggregate size fractions, by considering the effects of long-term application of farmyard manure (FYM) and mineral (Min) fertilization.
Materials and methods
Macroaggregates (250–2000 μm), microaggregates (53–250 μm), and silt–clay (<53 μm) fractions of three different soils (clayey, peaty, and sandy) were separated by wet sieving technique and then subjected to chemical and physical analysis. Sample porosity and pore size distribution were analyzed using mercury intrusion porosimetry (MIP), while SOC chemical structure was characterized by means of nuclear magnetic resonance (13C cross-polarization–magic angle spinning nuclear magnetic resonance (CP MAS 13C NMR)) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies.
Results and discussion
Results showed that FYM increased organic (OC) and humic carbon (HC) content compared to the Min fertilization and unfertilized soils. However, it caused a gradual decrease in O,N-alkyl C, and alkyl C of humic C from macroaggregate to silt–clay fractions, suggesting an advanced state of humic component degradation as revealed by CP MAS 13C NMR, DRIFT analyses. MIP analysis showed a clear increase of micropores (5–30 μm) and cryptopores (0.0035–0.1 μm) from macroaggregate to silt–clay fractions, while minor differences were observed among the treatments. The application of principal component analysis to mineral soil fractions identified the formation of three main clusters, where (i) macroaggregates of clayey soil were mainly associated to cryptopores and OC and (ii) microaggregates and silt–clay fraction were mainly isolated by carbonyl C, ultramicropores, and total porosity. The third cluster was associated with medium and fine sand of the sand soil fraction as coupled with O,N-alkyl C, anomeric C, mesopores, and HC/OC ratio.
Conclusions
Overall, this study indicates that pore size distribution may be a valuable indicator of soil capacity to sequester carbon, due to its direct influence on SOC linkages with soil aggregates and the positive effects against SOC decomposition phenomena. In this context, micropore- to nanopore-dominated structures (e.g., clayey soil) were able to protect OC compounds by interacting with mineral surfaces and intercalation with phyllosilicates, while meso/macropore-dominated structures (i.e., sandy soil) exhibited their low ability to protect the organic components
Stimulated Adsorption of Humic Acids on Capped Plasmonic Ag Nanoparticles Investigated by Surface-Enhanced Optical Techniques
No full textThe adsorption of humic substances on Ag nanoparticles (AgNPs) is of crucial environmental importance and determines the toxicity of these NPs and the
structure of adsorbed organic matter. In this work, the adsorption of two standard soil and leonardite International Humic Substances Society humic acids was studied on AgNPs of different sizes, shapes (spherical and star-like), and interfacial chemical compositions. Surface-enhanced optical (Raman and fluorescence) spectroscopies were used to follow the specific chemical groups involved in this adsorption. By means of the latter optical techniques, information regarding the binding mechanism and the macromolecular aggregation can be deduced. The influence of the surface chemical composition induced by the different functionalizations of the interfaces of these NPs is highly important regarding the chemical interactions of these complex organic
macromolecules. The surface functionalization with positively charged alkyl diamines led to a large increase in the adsorption as well as a strong structural rearrangement of the macromolecule once adsorbed onto the surface
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