Organic substances replenishment and high humus content of soil in the apple orchads under different fertilization

The balance of humus in a meter layer of dark gray, podzolized soil and podzolized chernozem of the experimental apple orchads and the study of their long-term fertilization was investigated (from the planting to 50-year old trees) with the use of organic (40 t/ha of cattle manure) and mineral fertilizers (N120P120K120), which were applied once in two years in autumn under the plowing in the row spacings at a depth of 18 20 cm. In the 20-year period (from 30- to 50-year-old experimental gardens) in a meter layer of dark gray podzolized soil on the non-fertilized control plots the amount of humus increased by 27 t/ha, and on the plots fertilized with manure – by 7 t/ha more and on the plots with mineral fertilizers – by 6 t/ha less and in podzolized chernozem – 37 t/ha and 3 t/ha more and 10 t/ha less respectively. Such changes in humus storage were caused by different replenishment of organic substances, and, to a greater extent, an increase in the biological activity of the fertilized soil, in particular the intensity of mineralization processes of organic matter, and in particular the humus compounds. Also, the replanishment of such soils in the gardens by the organic mass of fallen leaves and thin (d≤1mm) small roots, which systematically grows and dies, providing root nutrition of fruit plants, was investigated. These sources supplemented with organic substances the layer of soil of 0 20 cm – with all the mass of leaves and 38,5 43,3% of the total roots, and the increase in humus content was in all roots of the layer of 0 60 cm: in non-fertilized areas of 11 t/ha in dark gray soil and 18 tons per hectare in chernozem, under organic fertilizers, by 14 and 19 t/ha, and under mineral fertilizers – by 3 and 9 t/ha respectively. The greatest quantity of humus was added in the layer 60 100 cm: 16 and 19 t/ha, 20 and 21 t/ha and 18 t/ha. Such results were conditioned by the intensification of biological activity, in particular mineralization processes, in the upper layers of fertilized soils at higher humus content, as well as the migration of soluble humus substances deep into the meter profile.

Coupled nitrogen transformation and carbon sink in the karst aquatic system: a review

Carbonate bedrock regions represent that 14% of Earth's continental surface and carbon (C) sink in karst water plays an important role in the global C cycle due to the CO2 consumption during carbonate mineral weathering. Intensive agriculture and urbanization have led to the excessive input of nitrogen (N) into aquatic systems, while the high concentrations of inorganic C in the karst water might affect the N cycle. This paper summarized the characteristics of water in karst regions and discussed the N transformation coupled with the C cycle in the condition of high Ca2+ content, high pH, and high C/N ratios. Carbonates can consume more atmospheric and pedologic CO2 than non-carbonates because of their high solubility and high rate of dissolution, resulting in the higher average CO2 sink in karst basins worldwide than that in non-karst basins. Therefore, carbonate mineral weathering and aquatic photosynthesis are the two dominant ways of CO2 absorption, which are termed as coupled carbonate weathering. As the alkalinity and high C/N content of karst water inhibit the denitrification and mineralization processes, the karst aquatic environment is also served as the N sink.

Anion Composition of Apatite in the Au-Cu Epithermal Deposit of Palai-Islica (Almería, SE Spain) as an Indicator of Hydrothermal Alteration

The Palai-Islica deposit (Almería, SE Spain) is an Au-Cu epithermal deposit hosted in Neogene calc-alkaline andesites and dacites from the Cabo de Gata-Cartagena volcanic belt in the Betic Cordillera. Major element compositions of apatite from Palai-Islica orebody and related hydrothermally altered and unaltered volcanic rock from the region hosting the deposit were obtained to clarify the processes involved in their formation. Apatite in the host volcanic rocks is rich in chlorapatite and hydroxylapatite components (50–57% and 24–36%) and poor in fluorapatite components (12–21%), indicating assimilation processes of cortical Cl-rich material in the magmatic evolution. Apatite in the orebody sometimes has corrosion textures and is mostly fluorapatite (94–100%). Apatite from the hydrothermally altered host rock of the orebody systematically bears signs of corrosion and has variable and intermediate fluorapatite (19–100%), chlorapatite (1–50%), and hydroxylapatite (0–47%) components. The style of zonation and the composition are related to the proximity to the orebody. These features can be interpreted as the result of hydrothermal modification of high Cl, OH-rich volcanic apatites into F-rich apatites. The enrichment of F is related to the intensity of hydrothermal alteration and could therefore constitute a geochemical index of alteration and of mineralization processes.

Bio-Templating: An Emerging Synthetic Technique for Catalysts. A Review

In the last few years, researchers have focused their attention on the synthesis of new catalyst structures based on or inspired by nature. Biotemplating involves the transfer of biological structures to inorganic materials through artificial mineralization processes. This approach offers the main advantage of allowing morphological control of the product, as a template with the desired morphology can be pre-determined, as long as it is found in nature. This way, natural evolution through millions of years can provide us with new synthetic pathways to develop some novel functional materials with advantageous properties, such as sophistication, miniaturization, hybridization, hierarchical organization, resistance, and adaptability to the required need. The field of application of these materials is very wide, covering nanomedicine, energy capture and storage, sensors, biocompatible materials, adsorbents, and catalysis. In the latter case, bio-inspired materials can be applied as catalysts requiring different types of active sites (i.e., redox, acidic, basic sites, or a combination of them) to a wide range of processes, including conventional thermal catalysis, photocatalysis, or electrocatalysis, among others. This review aims to cover current experimental studies in the field of biotemplating materials synthesis and their characterization, focusing on their application in heterogeneous catalysis.

Evolution of Nb–Ta Oxide Minerals and Their Relationship to the Magmatic-Hydrothermal Processes of the Nb–Ta Mineralized Syenitic Dikes in the Panxi Region, SW China

Previous geochemical and petrological studies have concluded that initially magmatic Nb–Ta mineralization is often modified by post-magmatic hydrothermal fluids; however, there is still a lack of mineralogical evidence for the syenite-related Nb–Ta deposit. From the perspective of Nb–Ta minerals, the pyrochlore supergroup minerals have significance for indicating the fluid evolution of alkaline rock or related carbonatite type Nb–Ta deposits. The Panzhihua–Xichang (Panxi) region is a famous polymetallic metallogenic belt in southwestern China, abound with a huge amount of Nb–Ta mineralized syenitic dikes. This study focuses on the mineral textures and chemical compositions of the main Nb–Ta oxide minerals (including columbite-(Fe), fersmite, fergusonite-(Y), and especially pyrochlore group minerals) in samples from the Baicao and Xiaoheiqing deposits, in the Huili area, Panxi region, to reveal the magma evolution process of syenitic-dike-related Nb–Ta deposits. The Nb–Ta oxides in the Huili syenites are commonly characterized by a specific two-stage texture on the crystal scale, exhibiting a complex metasomatic structure and compositional zoning. Four types of pyrochlore group minerals (pyrochlores I, II, III, and IV) formed in different stages were identified. The euhedral columbite-(Fe), fersmite, and pyrochlores I and II minerals formed in the magmatic fractional crystallization stage. Anhedral pyrochlore III minerals are linked to the activity of magma-derived hydrothermal fluids at the late stages of magma evolution. The pyrochlore IV minerals and fergusonite-(Y) tend to be more concentrated in areas that have undergone strong albitization, which is a typical phenomenon of hydrothermal alteration. These mineralogical phenomena provide strong evidences that the magmatic-hydrothermal transitional stage is the favored model for explaining the Nb–Ta mineralization process. It is also concluded that the changes in chemical composition and texture characteristics for pyrochlore group minerals could serve as a proxy for syenite-related Nb–Ta mineralization processes.

Late Glacial and Holocene buried black soils in Emilia (northern Italy): genetic and paleoenvironmental insights

Purpose The existence of black horizons (BHs) is often highlighted in European soils, and in the Po River plain of northern Italy. Nevertheless, BH chronological frameworks and genetic models are still debated. The present study investigated the genesis of BHs in the eastern Po Plain where they are buried at various depths. Materials and methods Soil sequences were investigated with a multidisciplinary approach integrating geomorphologic, stratigraphic, pedologic, geochemical, isotopic, palynological, and radiometric analyses. Results and discussion The formation of the studied BHs was scattered over time from the Last Glacial Maximum to at least the middle Holocene. The new data indicate that BHs developed when the landscape was dominated by coniferous forest during conditions that were totally different from the current pedoclimatic setting. The recurrent presence of black particles indicates that this vegetation cover was systematically affected by fire episodes that induced soil degradation and mineralization processes of the original organic compounds, thus contributing to darkening of the upper soil horizons. Conclusions BH formation clearly coincided with cold time lapses. Evidence for repeated fire events (natural or human-induced?) provides insights for the controversial debate on early anthropogenic impacts on the environment.