Physical-chemical Conditions Research Articles

DEVELOPMENT OF A SYSTEM WITH SUSTAINABLE SUPPLEMENTAL HEATING: AN ALTERNATIVE TO COMBAT WATER SCARCITY

The scarcity of water resources has led researchers to investigate and develop mechanisms for the good use of saline and brackish waters to produce drinking water. In Brazil, the water crisis has always been a reality. The objective was to carry out desalination through a prototyped system with sustainable supplementary heating, to help supply drinking water to residents who face precarious living conditions. The research is aimed at the Bailique Archipelago and Sucuriju District, located in the extreme east of the State of Amapá and bathed by the Atlantic Ocean. It presents a quali-quantitative analysis, as it involves the construction of the prototype and temperature and physical-chemical tests of water samples. Regarding the results, desalination was carried out using a prototype, with subsequent analysis of the physical-chemical conditions of the interstitial waters to correlate with the potability parameters. The supplementary heating positioned on the sides of the system converged solar rays towards the greenhouse that contains salt water inside, and a device on the glass slope collected the condensed water. The 50cm x 50cm model desalinated 890mL and the 25cm x 25cm model desalinated 190mL of water in one day, reaching a maximum temperature of 91 ºC.

A new type of clay-Li deposit: Fault-controlled hydrothermal alteration in southern Hubei Province, China

Clay-Li deposits are among the major Li deposits in the world and occur mainly in sedimentary and/or volcanic-sedimentary strata. The Li orebodies are generally stratiform and stratibound, and Li is mainly hosted in various clay minerals. Here, we report a new type of clay-Li deposit that occurs along fault zones developed in metasedimentary rocks with significant alteration, and Li is also hosted in clay minerals in the Jinyinshan area in Xianning, southern Hubei Province, China. The study area has no granitic rock outcrops, but approximately 15 km south is the Mufushan granite batholith, where large-scale rare metal mineralization, such as Li, Be, Nb and Ta granitic pegmatites, developed in the internal and outer contact zones of the granite batholith. In this study, high-Li clay minerals, including chlorite, kaolinite and smectite, were identified. The enrichment of Li is closely related to hydrothermal activity along the F9 fault in the region. Hydrothermal apatite coexisting with Li-clay in the orebody along the fault zone yielded an in situ U–Pb age of 135.2 ± 13.9 Ma, which is in good agreement with the ages of granites and Li-pegmatites around the Mufushan batholith. Petrographic, geochemical, and chronological evidence suggests that the ore-forming fluids and Li were likely sourced from the Mufushan granite batholith or a similar blind granite at the depth of the study area; that is, the granite-derived ore-forming fluids can travel long distances along fault zones, and during this pathway, Li from the metasedimentary rocks (i.e., the Lengjiaxi Group) may also have been leached by the fluids and contributed to the Li mineralization in the Jinyinshan clay-Li deposit. The close spatial relationships among different clay minerals indicate that fluid physical–chemical conditions (changes in temperature) may play a crucial role in controlling the formation of Li-rich clay minerals. Our study indicates that the Mufushan area has great potential for hydrothermal clay-Li mineralization occurring in the Lengjiaxi Group metasedimentary rocks around the Mufushan batholith.

The sources and physical–chemical conditions of gold mineralization in the Qi189 porphyry deposit, Qiyugou gold orefield, Eastern Qinling

The Qiyugou gold orefield is situated in the Eastern Qinling. It is a magmatic hydrothermal system, which includes cryptoexplosive breccia-type, vein-type, and porphyry gold deposits. However, the gold sources and physical–chemical conditions of precipitation of the newly discovered porphyry gold deposit, the Qi189, have not yet been well studied. It also hinders the comprehensive understanding of magmatic–hydrothermal gold systems in the Qiyugou gold orefield. Thus, detailed field and microscopic observations, C–O–He–Ar isotopic analysis, in situ major/trace element analysis, and thermodynamic studies on the Qi189 porphyry gold deposit have been carried out in this study. This deposit has three hydrothermal stages: the (I) early quartz–K-feldspar–molybdenite–magnetite stage, (II) middle quartz–sericite–pyrite–Te–Bi-mineral stage, as well as (III) late calcite–quartz stage. The carbon and He–Ar isotopic compositions suggest deep-seated sources of ore-forming fluids with mantle component proportions of up to 37 %. Oxygen isotopic compositions indicate the gradual involvement of more meteoric water in ore-forming fluids during stages I–III. The meteoric water input and reduction in temperature and pressure in the early stage II increased oxygen fugacity and decreased the pH values of ore-forming fluids. Then, in hematite and sulfides formation during late stage II, the oxygen and sulfur fugacities of ore-forming fluids gradually decreased. Precipitation of native gold and Au-bearing telluride grains with quartz-sericite alteration in stage II is significant for Au enrichment, which occurred under acidic (pH = 3.64–5.71), low-logfO2 (<-34.86), low-logfS2 (−13.07 to −11.13) and low-logfTe2 (−15.55 to −10.32) conditions. Therefore, abundant mantle components and changes in the pH, logfO2, logfS2, and logfTe2 of the ore-forming fluids play important roles in gold enrichment. Combined with previous studies, this work also provides some new evidence for identifying a magmatic-hydrothermal gold system in this district, including similar sulfide trace elements, δ13CV-PDB compositions, and changes in logfO2 and logfS2 of various types of gold deposits in a gold orefield.

Pathogenic Factors of Shiga Toxigenic Escherichia coli

The Shigatoxigenic Escherichia coli (STEC) are bacterial enteropathogens responsible for some intensive clinical syndromes such as bloody diarrhoea, hemorrhagic colitis, hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and renal failure. These pathotypes come under the Enterohemorrhagic Escherichia coli (EHEC) group. Monogastric farm animals such as pigs, horses, chickens, ducks, turkeys and aquatic animals like shellfish, fishes, and wild animals can act as major spillover hosts of STEC strains and could serve as the potential source of infection. The pathogen is notorious as a quickly emergent strain with acquired characteristics like different variants of Shigatoxin, many antibiotic degrading enzymes, Intimin, Enterohemolysin, Auto-agglutination Adhesins, Catalase-peroxidase, Zinc metalloprotease, Subtilase cytotoxin, tolerance to multiple adverse conditions, and biofilm formation. The bacteria are known for its long survival in different adverse physical-chemical conditions. The formation of biofilm is one of the major factors responsible for their persistence. Multidrug resistance is another related trait contributing to the high mortality rate of these strains. STEC strains are good candidates for studying the emergence of pathogens with acquired characteristics like genes. In this article, various virulent traits and multidrug resistance that enabled the strain to emerge as a serious public health menace were reviewed.

Arsenic biomineralization and selenium nanoparticles biosynthesis by Halomonas boliviensis strain H-10 isolated from the high-altitude Salar de Huasco salt flat (Chile)

High-altitude Andean wetlands of the Atacama Desert (Chile), including the Salar de Huasco salt flat, are unusual environments characterized by a great variability of physical-chemical conditions, often combined with a high concentration of heavy metals, including arsenic (As) and semimetals, such as selenium (Se). Microorganisms present in these environments evolved adaptative strategies to cope with environmental stresses, with biotechnological potentials. The present work investigated the natural bacterial community composition in sediments collected from the Salar de Huasco salt flat, by high-throughput Illumina sequencing, and to isolate bacterial strains able to remove As and biosynthesize Se nanoparticles (SeNPs). Dominant taxonomic groups (abundance ≥1%) were affiliated to Proteobacteria (mainly consisting in Delta- and Alfa- Gamma-proteobacteria) Bacteriodetes, Firmicutes, Acidobacteria, Spirochaetes, Deinococcus-Thermus, Gemmatimonadetes and Verrucomicrobia. Halomonas boliviensis strain H-10 was able to both biomineralize As and biosynthesise SeNPs; therefore, the characteristics of H. boliviensis strain H-10 could be used for biotechnological purposes, including As bioremediation from water and bioproduction of SeNPs.

Fossil hydrothermal oceanic systems through in-situ B isotopes in ophicarbonates (N. Apennines, Italy)

In submarine-hydrothermal systems, fluid-rock interactions play a pivotal role in fostering life on rocky planets. Carbonated-ultramafic rocks (i.e., ophicarbonates) represent an important witness of such environments and their study may provide new insights into hydrothermal processes. Here, we report in-situ trace element concentrations and the first in-situ boron isotope analyses (δ11B) of serpentines from the Ligurian N. Apennine (Italy) ophicarbonates, which represent non-subducted remnants of Jurassic ultramafic-hosted hydrothermal system. Based on micro-Raman analyses, lizardite is the dominant stable serpentine polymorph in the studied samples, thus constraining the temperature (T) of serpentinization below ca. 320 °C. By means of UPb LA-ICP-MS calcite geochronology, the age of the carbonation event is constrained at 137 ± 3 Ma (2σ, n = 52). The increasing inventory of several fluid-mobile elements (e.g., B, Li, As, Sb, Sr, U) associated with the REE budget variability in serpentines from ophicarbonates compared to those in pure serpentinites suggest that physico-chemical changes during the evolution of the hydrothermal system exert a relevant influence on the geochemistry of serpentines. Pure serpentinites, which are considered the protoliths of the ophicarbonates, show positive δ11B signatures from +15.8 to +35.0‰ (n = 24), thus falling in the range of present-day oceanic and forearc serpentinites and ophiolite-derived serpentinites. The δ11B imprint of serpentines in ophicarbonates clusters at +10.2 ± 2.2‰ (2SD, n = 57) and − 5.7 ± 1.5‰ (2SD, n = 36). Remarkably, this is the first report of oceanic serpentines showing negative B isotope compositions. The positive δ11B data likely reflect inheritance from the precursor serpentinite, while the negative δ11B values are here related to the hydrothermal process(es). We attempt to model how the variation in pH and different δ11B composition of the hydrothermal vent fluids (+25 and + 8‰) at different T (100 and 150 °C) can affect the δ11B imprint of serpentines. Our results indicate that either pH condition or δ11B of the hydrothermal vent fluids can shift the δ11B of serpentines from positive to negative values. Our new trace element and δ11B data are integrated and discussed with those from the literature to achieve new constraints in the variations and controls on the physical-chemical conditions of fluid-rock interaction during the progressive evolution of long-lived fossil ultramafic-hosted hydrothermal system. Finally, we discuss how subduction processes can potentially modify the B geochemistry of ophicarbonates and the information that we could achieve by studying B isotopes in such high-P lithologies to unravel the B- and C-cycles into the Earth's mantle since the onset of modern plate tectonics.

Investigating the transport and colloidal behavior of Fe3O4 nanoparticles in aqueous and porous media under varying solution chemistry parameters.

The possible adverse effects of engineered iron oxide nanoparticles, especially magnetite (Fe3O4 NP), on human health and the environment, have raised concerns about their transport and behavior in soil and water systems. Accumulating these NPs in the environment can substantially affect soil and water quality and the well-being of aquatic and terrestrial organisms. Therefore, it is essential to examine the factors that affect Fe3O4 NP transportation and behavior in soil and water systems to determine their possible environmental fate. In this work, experiments were conducted in aqueous and porous media using an environmentally relevant range of pH (5, 7, 9), ionic strength (IS) (10, 50, 100 mM), and humic acid (HA) (0.1, 1, 10 mg L-1) concentrations. Fe3O4 NPs exhibited severe colloidal instability at pH 7 (⁓ = pHPZC) and showed an improvement in apparent colloidal stability at pH 5 and 9 in aquatic and terrestrial environments. HA in the background solutions promoted the overall transport of Fe3O4 NPs by enhancing the colloidal stability. The increased ionic strength in aqueous media hindered the transport by electron double-layer compression and electrostatic repulsion; however, in porous media, the transport was hindered by ionic compression. Furthermore, the transport behavior of Fe3O4 NPs was investigated in different natural waters such as rivers, lakes, taps, and groundwater. The interaction energy pattern in aquatic systems was estimated using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. This study showed the effects of various physical-chemical conditions on Fe3O4 NP transport in aqueous and porous (sand) media.

Novel Insights on the Bacterial and Archaeal Diversity of the Panarea Shallow-Water Hydrothermal Vent Field.

Current knowledge of the microbial diversity of shallow-water hydrothermal vents is still limited. Recent evidence suggests that these peculiar and heterogeneous systems might host highly diversified microbial assemblages with novel or poorly characterized lineages. In the present work, we used 16S rRNA gene metabarcoding to provide novel insights into the diversity of the bacterial and archaeal assemblages in seawater and sediments of three shallow-water hydrothermal systems of Panarea Island (Tyrrhenian Sea). The three areas were characterized by hot, cold, or intermediate temperatures and related venting activities. Microbial biodiversity in seawater largely differed from the benthic one, both in α-diversity (i.e., richness of amplicon sequence variants-ASVs) and in prokaryotic assemblage composition. Furthermore, at the class level, the pelagic prokaryotic assemblages were very similar among sites, whereas the benthic microbial assemblages differed markedly, reflecting the distinct features of the hydrothermal activities at the three sites we investigated. Our results show that ongoing high-temperature emissions can influence prokaryotic α-diversity at the seafloor, increasing turnover (β-)diversity, and that the intermediate-temperature-venting spot that experienced a violent gas explosion 20 years ago now displays the highest benthic prokaryotic diversity. Overall, our results suggest that hydrothermal vent dynamics around Panarea Island can contribute to an increase in the local heterogeneity of physical-chemical conditions, especially at the seafloor, in turn boosting the overall microbial (γ-)diversity of this peculiar hydrothermal system.

A MUSE/VLT spatially resolved study of the emission structure of Green Pea galaxies

Green Pea galaxies (GPs) present among the most intense starbursts known in the nearby Universe. These galaxies are regarded as local analogs of high-redshift galaxies, making them a benchmark in the understanding of the star formation processes and the galactic evolution in the early Universe. In this work, we performed an integral field spectroscopic (IFS) study for a set of 24 GPs to investigate the interplay between its ionized interstellar medium (ISM) and the massive star formation that these galaxies present. Observations were taken in the optical spectral range (λ4750 Å–λ9350 Å) with the MUSE spectrograph attached to the 8.2 m telescope VLT. Spatial extension criteria were employed to verify which GPs are spatially resolved in the MUSE data cubes. We created and analyzed maps of spatially distributed emission lines (at different stages of excitation), continuum emission, and properties of the ionized ISM (e.g., ionization structure indicators, physical-chemical conditions, dust extinction). We also took advantage of our IFS data to produce integrated spectra of selected galactic regions in order to study their physical-chemical conditions. Maps of relevant emission lines and emission line ratios show that higher-excitation gas is preferentially located in the center of the galaxy, where the starburst is present. The continuum maps, with an average angular extent of 4″, exhibit more complex structures than the emission line maps. However, the [O III]λ5007 Å emission line maps tend to extend beyond the continuum images (the average angular extent is 5.5″), indicating the presence of low surface brightness ionized gas in the outer parts of the galaxies. Hα/Hβ, [S II]/Hα, and [O I]/Hα maps trace low-extinction, optically thin regions. The line ratios [O III]/Hβ and [N II]/Hα span extensive ranges, with values varying from 0.5 dex to 0.9 dex and from −1.7 dex to −0.8 dex, respectively. Regarding the integrated spectra, the line ratios were fit to derive physical properties including the electron densities ne = 30 − 530 cm−3, and, in six GPs with a measurable [O III]λ4363 Å line, electron temperatures of Te = 11 500 K–15 500 K, so the direct method was applied in these objects to retrieve metallicities 12 + log(O/H)≃8. We found the presence of the high-ionizing nebular He IIλ4686 Å line in three GPs, where two of them present among the highest sSFR values (&gt; 8 × 108 yr−1) in this sample. Non-Wolf-Rayet (WR) features are detected in these galaxy spectra.

Geochronology and Geochemistry of Cretaceous Adakitic Rocks of the Dongguashan Cu Deposit in the Lower Yangtze River Belt: Insights into Petrogenesis and Mineralization

The Lower Yangtze River Belt (LYRB) is a well-known and important base area with regard to Cu polymetallic resources in China. Large Cu polymetallic deposits in the LYRB are strongly associated with Cretaceous adakitic rocks. However, the petrogenesis of the Early Cretaceous adakites and the temporal–genetic relationship with mineralization are still disputable. The Dongguashan (DGS) Cu polymetallic deposit in the Tongling ore cluster is one of the largest Cu deposits in the LYRB. The DGS intrusion mainly comprises quartz monzodiorite, with SiO2 contents varying from 63.7 to 67.9 wt%. Zircons from the quartz monzonite yield a SIMS U-Pb age of 138.9 ± 1.8 Ma, which indicates that the Cretaceous magmatism is coeval with mineralization. The studied rocks show typical geochemical signatures of adakites, characterized by high Al2O3 (14.9–16.2 wt%) and Sr (800–910 ppm) and low Y (15.2–17.5 ppm) and Yb (1.37–1.52 ppm) contents, with consequently high Sr/Y (46–61) and (La/Yb)N (14.8–18.5) ratios. The zircon δ18O values of the DGS adakites range from 5.7‰ to 7.3‰, indicating a heterogeneous source. Whole-rock Sr-Nd isotopic compositions show an enriched character, with ISr ratios from 0.70783 to 0.70794 and εNd(t) values around −11.0, which fall intermediately in the area of MORB (mid-ocean ridge basalt), marine sediment, and the ancient lower crust. Comprehensively, whole-rock geochemical compositions and isotopic values suggest that the adakites are generated from the partial melting of the subducted oceanic crust and possibly with the involvement of sedimentary materials derived from the slab or continental crust. Moreover, the bulk-rock high-Cu composition, and the physical–chemical conditions (high oxygen fugacity and high volatile contents) revealed by apatites, plays critical roles in the formation of Cu mineralization in the DGS Tongling ore cluster, LYRB.

Incorporating carbon sequestration into lake management: A potential perspective on climate change

Exploring the carbon sequestration capacity of water ecosystems would contribute to coping with climate change. This study conducted an integrated method framework to achieve an improved understanding of the relationship between carbon sequestration and lake ecosystem components, as well as provide a new perspective on climate change for policymakers. The vertically generalized production model revealed the carbon sequestration capacity of lakes. The hierarchical linear model identified the cross-scale factors affecting phytoplankton. Then a developed multi-agents-based model with scenario analysis provided adaptive management strategies for carbon sequestration. Furthermore, we applied the integrated framework in the 63 polluted lakes of Wuhan. The results showed that the average carbon sequestration per unit area was at 0.87 kgC·m−2·a−1, which was greater than that of the ocean and forest ecosystems, indicating that the lakes had a potential capacity for carbon sequestration. Total phosphorus had the strongest effect on the Chl-a (chlorophyll a) concentration (fixed effect (γ) =6.82, P < 0.1), followed by total nitrogen (γ = 6.38, P < 0.05), Rotifer biomass (γ = 1.95, P < 0.01) and water temperature (γ = 1.27, P < 0.05). These results indicated that the bottom-up effect of chemical factors on phytoplankton was greater than the top-down effect of zooplankton. The proportion of grassland at the whole-lakes level would have a negative synergistic impact on the Chl-a with changing the micro water temperature at the part-lakes level (γ = −46.64, P < 0.05). There was no significant interaction effect between land cover change and total nitrogen (phosphorus) on the Chl-a. Therefore, we could indirectly confirm that point source pollution emissions would synergistically affect the Chl-a and carbon sequestration along with the effects of physical-chemical conditions. The coordinated proportional control of nitrogen and phosphorus and the artificial controlling biomass of zooplankton-feeding fish were proposed to improve carbon sequestration and water quality for lake management.

Microbial mats as model to decipher climate change effect on microbial communities through a mesocosm study.

Marine environments are expected to be one of the most affected ecosystems by climate change, notably with increasing ocean temperature and ocean acidification. In marine environments, microbial communities provide important ecosystem services ensuring biogeochemical cycles. They are threatened by the modification of environmental parameters induced by climate change that, in turn, affect their activities. Microbial mats, ensuring important ecosystem services in coastal areas, are well-organized communities of diverse microorganisms representing accurate microbial models. It is hypothesized that their microbial diversity and metabolic versatility will reveal various adaptation strategies in response to climate change. Thus, understanding how climate change affects microbial mats will provide valuable information on microbial behaviour and functioning in changed environment. Experimental ecology, based on mesocosm approaches, provides the opportunity to control physical-chemical parameters, as close as possible to those observed in the environment. The exposure of microbial mats to physical-chemical conditions mimicking the climate change predictions will help to decipher the modification of the microbial community structure and function in response to it. Here, we present how to expose microbial mats, following a mesocosm approach, to study the impact of climate change on microbial community.

Multiple tectonic switches in the Eastern Tianshan, Central Asian Orogenic Belt: Implications for crustal growth and metallogenesis

Subduction zones are crucial sites for inputs of juvenile crust and the generation of porphyry copper deposits by arc magmatic processes that generally involve episodic trench advance and retreat. It is well documented that the generation of juvenile crust is associated with lithospheric extension during the retreat of subduction zones, whereas crustal reworking is associated with lithospheric compression in continental arcs during the advance of subduction zones. However, it remains unclear whether such models can be applied to island arc settings and how they relate to metallogenesis. To address this issue, we examine intermediate–felsic igneous rocks (∼460–300 Ma) of the Dananhu–Harlik island arc in the southern Central Asian Orogenic Belt. Our new and compiled data indicate three magmatic episodes in the Dananhu–Harlik island arc during the northward subduction of the Kangguer oceanic plate, with each involving a tectonic switch from compressional trench advance to extensional retreat. Crustal growth occurred mainly during the compressional stages of trench advance, which is in contrast with typical continental arcs. Tectonic transitions also controlled regional mineralization patterns, and the typical porphyry and related skarn-type deposits formed during subduction zone advance, whereas volcanogenic massive sulfide (VMS) deposits and overprinting mineralization were generated during subduction zone retreat. A combination of all data on tectonic settings and physical–chemical conditions (e.g., temperature, oxygen fugacity, and water content) of the pre-mineralization and ore-related intrusions led us to the conclusion that normal intra-crustal arc magmatic processes, involving sulfide pre-enrichment and reactivation, generated the typical Tuwu–Yandong porphyry Cu deposits in the Dananhu arc without the prerequisite of slab melting. Our study provides an excellent example of crustal growth in an island arc setting as well as metallogenesis during the repeated advance and retreat of a subduction zone.

Analysis of The Relationship Between Community Behavior on Physical-Chemical Conditions of Waters in The Waterways of Debegan Village

People’s behavior correlates with the quality of water in rivers such as activities household, agriculture, and unprocessed industry. In Debegan Village, the condition of the waterways can be seen invisibly and there is a decrease in water quality in the waterways. This study aims to determine the value of water’s physical and chemical character from waterways in Debegan Village, which is then connected with community behavior regarding their anthropogenic activities. The research method used in this study is a combination of descriptive quality and quantitative analysis methods. Analysis of water quality status Referring to the Decree of the Minister of Environment Number 115 of 2003 concerning Determination of Water Quality Status, one of the methods used to determine the level of pollution relative to several parameters of water quality is the Pollution Index (PI). The results of the analysis showed that the waterways in Debegan Village were proven to be lightly polluted with mildly polluted status. the values of temperature, turbidity, pH, DO, and salinity showed a number that not accordance the quality threshold, there was a linkages between existing pollution and community behavior, especially in aspects of actions against the background of tofu industry activities. The problem suggestion of this condition is to develop a community-based concept that emphasizes public participation, community education, and sustainability.

Computational simulation of the ore-forming processes associated with the Sanshandao-Haiyu gold belt, Jiaodong Peninsula, eastern China: implications for the duration of ore formation

The Sanshandao-Haiyu gold belt, Jiaodong Peninsula, Eastern China accounts for more than 1,400 t gold resources, which is always recognized as a coupled result of structural deformation, pore-fluid flow, and hydrothermal alteration-mineralization processes. However, the ore-forming processes associated with this gold belt has not been fully understood by the coupled perspective. In this paper, we use computational modeling to study the spatial distribution of dilation (positive volumetric strain) and the mineralization rate, which can predict the mineralization patterns from a chemical perspective, so as to solve the fully coupled problem during ore-forming processes. The model was loaded on the FLAC3D platform to test four scenarios: 1) Syn-compression in the NW-SE direction; 2) syn-compression in the WNW-ESE direction; 3) syn-compression in the NNW-SSE direction, and 4) syn-extension in the NW-SE direction. The simulation results show that only the syn-compressional scenario can produce wide dilation zones with a distribution pattern similar to the known orebodies. The higher dilation zones with the volumetric strain (&amp;gt;0.1%) and the highest pore-fluid flux are closely associated with the fault geometry, particularly for the gentle segments near the steep-flat transition areas. Besides, the dilation zones also occur with very high absolute values of pore-fluid pressure gradient and temperature gradient, indicating significantly perturbed physical-chemical conditions. The receiver operating characteristic (ROC) curves of the mineralization rate show that the area under the curve (AUC = 0.862) of the NW-SE syn-compression model is the highest among these four scenarios, indicating a major paleo compression stress direction of NW-SE during ore-forming period. Furthermore, based on the mineralization rate, we estimated that the mineralization duration of the Sanshandao-Haiyu gold belt would be less than 100,000 years. These simulation results can not only enhance our understanding of the ore-forming processes in the Sanshandao-Haiyu gold belt and Jiaodong Peninsula but also demonstrate that these can be used directly or indirectly for deep mineral exploration.

Recovery through proper grazing exclusion promotes the carbon cycle and increases carbon sequestration in semiarid steppe

Grazing exclusion changes soil physical-chemical characteristics, rapidly affects microbial community composition and function, and alters biogeochemical processes, e.g., carbon (C) cycle, over time. However, the temporal dynamics of CO2 emission and CH4 uptake during grassland restoration chronosequences remain poorly understood. We investigated soil CO2 emission and CH4 uptake, the genes related to CO2 and CH4 production and reduction (cbbL, cbbM, chiA, and pmoA), and associated microbial communities under different durations of grazing exclusion (0, 7, 16, 25, and 38 years) to reveal the mechanisms and potential of soil CO2 emission and CH4 uptake in a semi-arid steppe. The results showed that a proper exclusion period could significantly improve soil physical-chemical conditions, vegetation community, and soil C-cycling. The abundance of C-cycling functional genes (cbbL, cbbM, chiA and pmoA), CH4 uptake and CO2 emission rates showed a single-peak pattern with increasing duration of grazing exclusion, peaking at 16 years and then decreasing in the period between 25 and 38 years, indicating that the effect of exclusion weakened when the exclusion period was too long. The changes in C-cycling functional genes and microbial communities are primarily influenced by aboveground net primary productivity (ANPP), and are associated with CO2, CH4, soil water content (SWC), and soil organic carbon (SOC). Structural equation modeling showed that increases in SOC content and pmoA abundance caused by an increase in ANPP accelerated CO2 emission and CH4 uptake rates, respectively. Our results provide valuable insights into the critical role of grazing exclusion in promoting grassland restoration and carbon sequestration, and have potential implications for sustainable land management practices.

Effect of Mechanical Microenvironment on Collagen Self-Assembly In Vitro.

Collagen, as a structural protein, is widely distributed in the human body. Many factors influence collagen self-assembly in vitro, including physical-chemical conditions and mechanical microenvironment, and play a key role in driving the structure and arrangement. However, the exact mechanism is unknown. The purpose of this paper is to investigate the changes in the structure and morphology of collagen self-assembly in vitro under mechanical microenvironment, as well as the critical role of hyaluronic acid in this process. Using bovine type I collagen as the research object, collagen solution is loaded into tensile and stress-strain gradient devices. The morphology and distribution of collagen is observed using an atomic force microscope while changing the concentration of collagen solution, mechanical loading strength, tensile speed, and ratio of collagen to hyaluronic acid. The results demonstrate that the mechanics field governs collagen fibers and changes their orientation. Stress magnifies the differences in results caused by different stress concentrations and sizes, and hyaluronic acid improves collagen fiber orientation. This research is critical for expanding the use of collagen-based biomaterials in tissue engineering.

Seasonal Upwelling Conditions Modulate the Calcification Response of a Tropical Scleractinian Coral

Natural processes such as upwelling of deeper-water masses change the physical-chemical conditions of the water column creating localized ocean acidification events that can have an impact on the natural communities. This study was performed in a coral reef system of an archetypical bay within the Tayrona National Natural Park (PNNT) (Colombia), and aimed to quantify net calcification rates of a foundational coral species within a temporal context (6 months) taking into account the dynamics of seasonal upwelling that influence the study area. Net calcification rates of coral fragments were obtained in situ by the alkalinity anomaly technique in short-term incubations (~2.5 h). We found a significant effect of the upwelling on net calcification rates (Gnet) (p &lt; 0.05) with an 42% increase in CaCO3 accretion compared to non-upwelling season. We found an increase in total alkalinity (AT) and dissolved inorganic carbon (DIC) with decreased aragonite saturation (Ωara) for the upwelling months, indicating an influence of the Subtropical Under Water mass (SAW) in the PNNT coral community. Significant negative correlations between net calcification with temperature and Ωara, which indicates a positive response of M. auretenra with the upwelling conditions, thus, acting as “enhancer” of resilience for coral calcification.

APATITE VOLATILE CONTENTS OF PORPHYRY Cu DEPOSITS CONTROLLED BY DEPTH-RELATED FLUID EXSOLUTION PROCESSES

Abstract Porphyry Cu deposits are formed by Cu- and volatile (e.g., Cl, S)-rich fluids exsolved from underlying magma reservoirs. Intuitively, higher magmatic Cl and S contents likely correspond to higher magma fertility. However, the Cl contents of syn-ore magmatic apatite, one of the major Cl-bearing mineral phases in magmas, are highly variable among deposits (from &amp;lt;0.1 to &amp;gt;2 wt %). These variations may be controlled by different timing of apatite crystallization relative to fluid saturation among deposits, but the causes of these different relative timings remain obscure. Here we compile existing chemical data of magmatic apatite and amphibole phenocrysts from 25 porphyry Cu deposits worldwide and use these data to calculate magmatic physical-chemical conditions, such as water contents and magma reservoir depths. We find that the porphyry Cu deposits associated with deeper magma reservoirs are characterized by systematically higher magmatic H2O contents and apatite Cl, but lower apatite F contents and F/Cl ratios compared to shallower deposits. These correlations are best explained by early fluid exsolution and Cl loss that predate apatite crystallization in shallower porphyry Cu systems, which leads to elevated apatite F/Cl ratios. This is supported by the common occurrence of primary fluid inclusions in apatite from shallower systems. Postsubduction porphyry Cu deposits are normally associated with lower apatite Cl contents and shallower magma reservoirs, which is attributed to their formation under relatively extensional tectonic regimes. Our results demonstrate that the magma reservoir depth exerts an important control on the timing of fluid exsolution and accompanying Cl loss. In contrast, relatively high and constant apatite S content among deposits is minimally affected by fluid exsolution, possibly due to buffering of early-saturated sulfate in oxidized and S-rich magmas, and therefore might be used as a better potential fertility indicator than Cl.

An empirical calibration of the serpentine-water oxygen isotope fractionation at T = 25–100 °C

The ability to precisely constrain the physical–chemical conditions of serpentinization, such as temperature and fluid source, is limited by the accuracy of calibrations for oxygen isotope fractionation between serpentine and water – i.e., 1000 lnα(serpentine-water) – which disagree by up to 20‰ when extrapolated to T < 200 °C. In this study, we present a new empirical calibration of 1000 lnα(serpentine-water) aiming to improve applications of oxygen isotope geochemistry to very low-T serpentinization (T < 100 °C). We used the high-spatial resolution capabilities of Secondary Ion Mass Spectrometry (SIMS) to analyze oxygen isotope ratios in mineral pairs of calcite + serpentine, quartz + serpentine and talc + serpentine co-crystallized at scales ≤ 50 μm in six serpentinite samples from the Samail ophiolite (Oman). SIMS analysis shows that the mineral pairs are relatively homogenous in oxygen isotope ratios with variability in δ18O values ≤2‰ (2 s). Clumped isotope thermometry and petrological constraints indicate crystallization temperatures from 25 to 100 °C for the investigated samples. These independent constraints on temperature allowed us to derive 1000 lnα(serpentine-water) by combining Δ18O(quartz-serpentine), Δ18O(talc-serpentine) and Δ18O(calcite-serpentine) measured by SIMS in the investigated samples with Δ18O(quartz-water), Δ18O(talc-water) and Δ18O(calcite-water) calibrations available in the literature. Our empirical calibration of 1000 lnα(serpentine-water) = 1.04 ± 0.20 (2SE) × 106/T2 (T in K), from T = 25 to 100 °C, is within uncertainty of former high-temperature empirical calibrations extrapolated to T < 100 °C and matches experimental calibrations when extrapolated to T = 250 °C. The new serpentine-water calibration enables more accurate reconstructions of fluid-rock interactions occurring during low-temperature serpentinization processes in various tectonic settings.