Coexistence Zone Research Articles

Mapping Paddy Rice in Rice–Wetland Coexistence Zone by Integrating Sentinel-1 and Sentinel-2 Data

Accurate mapping of vegetation in the coexisting area of paddy fields and wetlands plays a key role in the sustainable development of agriculture and ecology, which is critical for national food security and ecosystem balance. The phenology-based rice mapping algorithm uses unique flooding stages of paddy rice, and it has been widely used for rice mapping. However, wetlands with similar flooding signatures make rice extraction in rice–wetland coexistence challenging. In this study, we analyzed phenology differences between rice and wetlands based on the Sentinel-1/2 data and used the random forest algorithm to map vegetation in the Poyang Lake Basin, which is a typical rice–wetland coexistence zone in the south of China. The rice maps were validated with reference data, and the highest overall accuracy and Kappa coefficient was 0.94 and 0.93, respectively. First, monthly median composited and J-M distance methods were used to analyze radar and spectral data in key phenological periods, and it was found that the combination of the two approaches can effectively improve the confused signal between paddy rice and wetlands. Second, the VV and VH polarization characteristics of Sentinel-1 data enable better identification of wetlands and rice. Third, from 2018 to 2022, paddy rice in the Poyang Lake Basin showed the characteristics of planting structure around the Poyang Lake and its tributaries. The mudflats were mostly found in the middle and northeast of Poyang Lake, and the wetland vegetation was found surrounding the mudflats, forming a nibbling shape from the lake’s periphery to its center. Our study demonstrates the potential of mapping paddy rice in the rice–wetland coexistence zone using the combination of Sentinel-1 and Sentinel-2 imagery, which would be beneficial for balancing the changes between paddy rice and wetlands and improving the vulnerability of the local ecological environment.

High temperature performance of RE2Zr2O7 high-entropy ceramics designed by thermophysical performance-oriented principle

This study utilizes modulation of ionic disorder and electronegativity differences for targeted component design of high-entropy ceramic compositions. A series of novel multicomponent ceramics with the general formula (LaGdYSm)x2Ybx1Zr2O7 (x1+4x2 = 2, x1 = 0.6,0.4,0.2,0) were prepared by solid-state reaction. The evolution patterns of their microstructures were analyzed using XRD and TEM, and the anti-sintering ability and thermophysical properties were evaluated. The results confirm that the multicomponent ceramics gradually transform from the coexistence of pyrochlore/fluorite dual-phase structure to pyrochlore structure with the tuning of the size disorder degree. After 50h of exposure to air at 1500 °C, the ceramics retained excellent phase stability. Segregation of La and Yb elements with large differences in radius size occurs, forming a mixture of the La-rich pyrochlore and the Yb-rich fluorite phases. The specimen with the maximum size disorder exhibits the lowest grain growth rate and the greatest thermal insulation properties. Large lattice distortions and sluggish diffusion effects are responsible for the mutual inhibition of grain growth in the two-phase coexistence zone. The thermal insulation properties of the ceramics show well correlated with the degree of the size disorder, further validating the effectiveness of the component design. Meanwhile, the thermal expansion coefficients of prepared ceramic can reach 11.49 × ∼11.58 × 10−6 K−1 at 1000–1100 °C. The customization principles used in this work fill a gap in the compositional design methodology for multicomponent lanthanum zirconate-based high-entropy ceramics. It is essential for developing rare-earth zirconates with tunable thermophysical properties in the area of thermal barrier coatings.

Early warning and management of invasive crop pests under global warming: estimating the global geographical distribution patterns and ecological niche overlap of three Diabrotica beetles.

Invasive alien pests (IAPs) pose a major threat to global agriculture and food production. When multiple IAPs coexist in the same habitat and use the same resources, the economic loss to local agricultural production increases. Many species of the Diabrotica genus, such as Diabrotica barberi, Diabrotica undecimpunctata, and Diabrotica virgifera, originating from the USA and Mexico, seriously damaged maize production in North America and Europe. However, the potential geographic distributions (PGDs) and degree of ecological niche overlap among the three Diabrotica beetles remain unclear; thus, the potential coexistence zone is unknown. Based on environmental and species occurrence data, we used an ensemble model (EM) to predict the PGDs and overlapping PGD of the three Diabrotica beetles. The n-dimensional hypervolumes concept was used to explore the degree of niche overlap among the three species. The EM showed better reliability than the individual models. According to the EM results, the PGDs and overlapping PGD of the three Diabrotica beetles were mainly distributed in North America, Europe, and Asia. Under the current scenario, D. virgifera has the largest PGD ranges (1615 × 104 km2). In the future, the PGD of this species will expand further and reach a maximum under the SSP5-8.5 scenario in the 2050s (2499 × 104 km2). Diabrotica virgifera showed the highest potential for invasion under the current and future global warming scenarios. Among the three studied species, the degree of ecological niche overlap was the highest for D. undecimpunctata and D. virgifera, with the highest similarity in the PGD patterns and maximum coexistence range. Under global warming, the PGDs of the three Diabrotica beetles are expected to expand to high latitudes. Identifying the PGDs of the three Diabrotica beetles provides an important reference for quarantine authorities in countries at risk of invasion worldwide to develop specific preventive measures against pests.

Study on Land Use Realities in “People and Nature Coexistence Zones” within the Urbanization Control Area of Kobe City

Study on Land Use Realities in “People and Nature Coexistence Zones” within the Urbanization Control Area of Kobe City

The Rapid Boiling of Thin Liquid Films with Different Thicknesses on Nanochannel Copper Plates: A Molecular Dynamics Study

Boiling heat transfer on nanostructured surfaces presents great potential in cooling highly integrated microelectronic devices. Analysis of the factors affecting boiling heat transfer included the analysis of nanostructure and wettability, indicating that consideration of the influence of working liquid quantity is essential in finite spaces. Rapid boiling water films with various thicknesses placed on the same nanochannel copper plate were studied via molecular dynamics (MD) simulations. The simulation results reveal that the potential energy difference in the vapor–liquid coexisting region on the nanochannels was lower for thicker films, and the evaporation rate was lower. The effect of water film thickness on boiling heat transfer is closely related to the potential energy difference in the vapor–liquid coexisting region on the nanochannels. The heat transfer effect was the worst in case 1, where the water thickness was lower than the height of the nanochannels. This is because there is no guaranteed liquid replenishment at the nucleation points, although the potential energy difference was greatest in the vapor–liquid coexistence zone of case 1. Evaporation was the greatest in case 2, where the water film just covered the nanochannels because of the larger potential energy difference and sufficient liquid water replenishment. This study is of great significance for the analysis of the vapor–liquid flow mechanisms of micro/nanostructured surfaces and the improved design of thermal management equipment of micro/nano devices.

Research on the coupled hazardous zones of coal self-ignition and CH4 blast in goaf during upward mining

During upward mining in coal mines, the gas in the lower goaf can flow to the upper goaf along the through fractures between the coal seams, which affects the distribution of the flow field such as the oxygen concentration and the gas concentration in the upper goaf. This paper explores the changes in the distribution regularity of the self-ignition zone in the goaf and the region coupled with the gas explosion range by comparing it with single-seam mining, taking the upward mining of a coal mine in Shanxi Province as an example. In this study, PFC2D software is used to simulate the range and voidage ratio of the first through fissure between close coal seams during up-mining. Then the distribution laws which of self-ignition zones and CH4 explosion ranges in the goaf under the two types of mining methods were compared and analysed using Fluent. Finally, according to the degree of overlapping between the self-ignition zone and CH4 explosion range, the distribution law of the two hazardous coexistence zones in the goaf was analysed. The research results are important for rapid identification and prevention of the above disaster areas.

MRI insight on multiphase flow in hydrate-bearing sediment and development mechanism of hydrate seal

Gas and water migration through the hydrate-bearing sediment are characteristic features in marine gas hydrate reservoirs worldwide. However, there are few experimental investigations on the effect of water-gas flow on the gas hydrate reservoir. In this study, gas-water migration in gas hydrate stability zone (GHSZ) was investigated visually employing a high-resolution magnetic resonance imaging (MRI) apparatus, and the formation of hydrate seal was experimentally investigated. Results revealed that normal flow of gas-water at the low flow rate of 1–0.25 mL/min will induce the hydrate reformation. Conversely, higher gas-water flow rates (at 2–0.5 and 4–1 mL/min) need higher reservoir pressure to induce the hydrate reformation. In addition, the hydrate reformation during the gas-water flow process produced the hydrate seal, which can withstand an over 9.0 MPa overpressure. This high overpressure provides the development condition for the underlying gas and/or water reservoir. A composite MRI image of the whole hydrate seal was obtained through the MRI. The pore difference between hydrate zone and coexistence zone produces a capillary sealing effect for hydrate seal. The hydrate saturation of hydrate seal was more than 51.6%, and the water saturation was more than 19.3%. However, the hydrate seal can be broken through when the overpressure exceeded the capillary pressure of the hydrate seal, which induced the sudden drop of reservoir pressure. This study provides a scientific explanation for the existence of high-pressure underlying gas below the hydrate layer and is significant for the safe exploitation of these common typical marine hydrate reservoirs.

Fear-driven extinction and (de)stabilization in a predator-prey model incorporating prey herd behavior and mutual interference

<abstract><p>The indirect effect of predation due to fear has proven to have adverse effects on the reproductive rate of the prey population. Here, we present a deterministic two-species predator-prey model with prey herd behavior, mutual interference, and the effect of fear. We give conditions for the existence of some local and global bifurcations at the coexistence equilibrium. We also show that fear can induce extinction of the prey population from a coexistence zone in finite time. Our numerical simulations reveal that varying the strength of fear of predators with suitable choice of parameters can stabilize and destabilize the coexistence equilibrium solutions of the model. Further, we discuss the outcome of introducing a constant harvesting effort to the predator population in terms of changing the dynamics of the system, in particular, from finite time extinction to stable coexistence.</p></abstract>

The achieving enhanced piezoelectric performance of KNN-based ceramics: Decisive role of multi-phase coexistence induced by lattice distortion

Multi-phase coexistence induced by phase boundary regulation is an efficient approach to promote the performance of (K, Na)NbO3 ceramics. Here, [(1-x) (K0.5Na0.5)(Nb0.965Sb0.035)O3 - x (Bi0.5Na0.5)HfO3, x = 0, 0.01, 0.02, 0.03, 0.04, 0.05] [(1-x) KNNS - x BNH] lead-free piezoceramics are prepared through solid-state sintering method. The changes of internal phase structure are analysed by systematic measurements, from which the coexistence of rhombohedral-tetragonal (R-T) multi-phase is confirmed at x = 0.04. The lattice distortion caused by BNH doping induces the coexistence of R-T multi-phase, consequently achieving the best comprehensive properties at x = 0.04 (d33 = 353 pC/N, TC = 285 ℃, εr = 6517, Pr = 15.3208 μC/cm2), which is due to the reduced domain wall energy and more easily deflected domains in the R-T multi-phase coexistence zone. This work is helpful to understand the essence of the multi-phase coexistence caused by doping to improve the piezoelectric performance.

The Imprint of Droughts on Mediterranean Pine Forests

Triggered by frequent high temperatures and scarce precipitation, droughts are a recurrent phenomenon in the Mediterranean Basin, causing significant impacts on forests. We analyzed the effects of drought intensity, duration, and seasonality on tree growth by investigating the relationship between the Standardized Precipitation-Evapotranspiration Index (SPEI) at different time scales and tree-ring width (TRW) in three pine species (Pinus halepensis Mill., P. sylvestris L, and P. uncinata Ramond ex A.DC) throughout a dense dendrochronological network in the Mediterranean Basin. We used generalized linear mixed models to predict such values over the entire distribution of the analyzed species. Furthermore, in areas where the species coexist, we analyzed the same parameters to highlight differences in their responses to similar climatic conditions. Our results showed that the maximum intensity of drought-affected conifers occurred more in the southern areas of the Spanish Mediterranean coast, especially P. halepensis, with maximum values of r = 0.67, while in the rest of the study area, the intensity decreased with elevation; we obtained maximum values of r = 0.40 and r = 0.33 for P. sylvestris and P. uncinata, respectively. This spatial distribution was also related to the duration of the drought impacts, showing that areas with lower intensity had shorter durations (2–4 months). We observed a latitudinal pattern in the seasonality of the drought impacts, with earlier growing seasons at high elevations (June–August) and later ones in the semi-arid Mediterranean. Similar intensity impacts were found in P. halepensis and P. sylvestris coexistence zones, although P. halepensis had a much longer duration and an earlier beginning of seasonality. Higher intensity, duration, and seasonality of drought effects were observed for P. sylvestris in areas where P. sylvestris and P. uncinata are distributed sympatrically. Understanding the plasticity and climatic response of these common southern European species to different types of droughts is crucial in the context of climate change where droughts are increasing in frequency and intensity.

High energy storage density and efficiency in (Bi0.5Na0.5)0.94Ba0.06TiO3-based ceramics with broadened and flattened dielectric peaks

Currently, Bi0.5Na0.5TiO3-based lead-free ferroelectrics have attracted considerable attention as one of the promising candidates for dielectric materials due to their large spontaneous polarization, environmental friendliness and low cost. However, their poor energy density hinder the practical application of the materials. Herein, a novel ceramic of (1-x) (0.94Bi0.5Na0.5TiO3-0.06BaTiO3)-x(0.96NaNbO3-0.04CaSnO3) (BNBT-xNNCS) has been developed by the solid solution of antiferroelectric NaNbO3–CaSnO3 into ferroelectric Bi0.5Na0.5TiO3–BaTiO3 and the microstructure and electrical properties of the material have been systematically investigated. All the ceramics are lied within the coexistence zone of tetragonal (T) and rhombohedral (R) phases, ensuring to the large polarizations of the materials. Importantly, the introduction of NaNbO3–CaSnO3 shifts dielectric peaks at Ts towards room temperature and simultaneously broadens and flattens the dielectric peaks, destroying the ferroelectric long-range order of ferroelectric domains and inducing the generation of polar nanoregions (PNRs) to reduce the remanent polarization. As a result, the prominent energy storage properties with the charge energy storage density (Wtot) of 1.86 J/cm3, recoverable energy density (Wrec) of 1.64 J/cm3 and energy storage efficiency (η) of 88.23% are obtained in the BNBT-xNNCS ceramics with x = 0.20 (BNBT-20NNCS) under a comparatively low electric field strength of 149 kV/cm, accompanying with superior frequency (ΔWrec ≤ 3%, Δη ≤ 3%, 30–90 Hz) and thermal stability (ΔWrec ≤ 10%, Δη ≤ 10%, 25–175 °C).

Widom line of supercritical CO2 calculated by equations of state and molecular dynamics simulation

Supercritical CO2 has been widely applied in power cycle owing to the exceptional physical property in the supercritical region. The Widom line is very important to reveal the pseudo-boiling mechanism of supercritical CO2 which plays significant influence on design and optimization of power cycle. In this paper, the Widom lines for supercritical CO2 in terms of thermodynamic response functions are constructed using equation of state (EoS) and molecular dynamics (MD) simulation. Different equations of state and CO2 models are proposed and applied to predict the various thermodynamic properties. The results show that the Peng-Robinson (PR) series equations of state play better performance in predicting the thermodynamic properties and the average absolute relative deviation is around 5.7 % compared to the NIST database. The TraPPE model could represent a very good agreement with the experimental values at different pressures with about 1~6 % deviation. Owing to large temperature interval for molecular dynamics, the simulated values could not capture the dramatic change of thermodynamic properties at low temperature region (295 ℃< T < 310 ℃), resulting in that the simulated thermodynamic properties by molecular dynamics are generally lower than that calculated by Peng-Robinson equation of state. When the temperature is larger 335 K, the deviation of Widom lines between the NIST and PR EoS decreases gradually with the temperature. Nonetheless, all the Widom lines could fall into the coexistence zone of liquid-like and gas-like phase which is surrounded by the isobaric temperature boundaries.

Effects of B2O3 doping on the dielectric and piezoelectric properties of (K,Na,Li)NbO3–BaZrO3–(Bi,Na)TiO3 ceramics

(K,Na,Li)NbO3–BaZrO3–(Bi,Na)TiO3–xB2O3 (KNLN–BZ–BNT–xB2O3) ceramics were prepared by the conventional solid-state reaction method. The effects of B2O3 content on dielectric and piezoelectric properties of KNLN–BZ–BNT ceramics were studied. Based on identification by X-ray diffraction, all samples showed a two-phase coexistence zone consisting of rhombohedral and tetragonal phases. It was found that B2O3 addition is effective both for obtaining a dense structure and for increasing the grain size of KNLN–BZ–BNT ceramics sintered at a low temperature. For ceramics with x = 0.5 wt%, the sintering temperature was observed to reduce from 1200 °C to 940 °C, while the samples maintained a high relative density around 97%. Because of the high densification and large grain size, the dielectric and piezoelectric properties improved. As a result, the ceramics with x = 0.5 wt% sintered at 940 °C exhibited good properties of d 33 = 197 pC N–1, k p = 0.29, tan δ = 0.029 and ε r = 1889, together with a Curie temperature (T c) of 222 °C.

The correlation between the covalent bonds and magnetocaloric properties of the Mn2−xFexPyGe1−yMz compounds

In recent years, MnFePGe magnetocaloric materials have been widely studied as promising candidates for magnetic refrigeration materials. The Curie temperature of MnFePGe can be adjusted to around room temperature by changing the element ratio or doping with other elements. Due to its first-order magnetic and structural transition, it engenders a large entropy change but unfortunately also exhibits a large thermal hysteresis during the phase transition, which leads to energy loss and lower refrigeration capability. In this paper, we establish a correlation between the in-plane covalent bonding and Curie temperature (TC), thermal hysteresis (ΔThys), two-phase coexistence zone (ΔTcoex), and entropy change (ΔSDSC) using 54 Mn2−xFexPyGe1−yMz (where M is a metallic or nonmetallic doped element) samples with different components. Neutron diffraction and XRD diffraction data and refinements have been employed to allow a detailed electron density reconstruction of six typical samples with the maximum entropy method. We find that the length of the in-plane bonding is closely correlated with the TC and ΔThys, while the TC, ΔThys, ΔTcoex, and ΔSDSC have no significant correlation with the length of the interlayer covalent bond. Moreover, we find that the ΔThys correlates most strongly with the change in the bond length when undergoing the paramagnetic-to-ferromagnetic phase transition rather than the absolute value of the bond length. These results provide an understanding of how to control the properties, enabling effective ways to tune the composition of magnetic refrigeration materials to tailor magnetocaloric properties for optimal performance.

Analysis of corrosion resistance of lightweight aluminum alloy sheet in the friction-stir joint area

In this thesis, 1 mm thick 6061 aluminum alloy plates are connected using a friction stir joining device, and the metallographic structure and corrosion resistance of the friction stir joint area obtained with different process parameters are systematically analyzed. The results show that the core region of the joint is composed of small equiaxed crystals, and the grains in the heat-affected zone are elongated in the direction of stirring flow. The grain sizes of the heat-affected zone is different, and it is a coexistence zone of grains of various sizes. When the rotation speed of the stirring head is 15000 rpm and the forward speed of the stirring head is 300 mm/min, the self-corrosive potential of the connection area is optimized during electrochemical corrosion, and thus the self-corrosion current is the smallest. With this parameter, the joint area has the best corrosion resistance.

Surface oxidation of nanocrystalline CVD TiB2 hard coatings revealed by cross-sectional nano-analytics and in-situ micro-cantilever testing

Nanocrystalline TiB2 coatings grown by chemical vapour deposition (CVD) are employed e.g. as hard protective coatings on cemented carbide cutting tools, owing to their high wear resistance, hardness and melting point, as well as superior thermal stability. This work applied novel cross-sectional nano-analytical techniques to investigate the effects of prolonged surface oxidation of a CVD bi-layer coating of ~3.4 μm thickness, consisting of a nanocrystalline TiB2 protective top layer and a TiN diffusion-barrier bottom layer. Synchrotron X-ray diffraction with a nano-focussed 70 nm beam revealed cross-sectional phase compositions and residual stress gradients in the coating in as-deposited and oxidised states. Transmission electron microscopy showed a clear oxidation front, the existence of a ~400 nm thick zone of coexistence of TiB2 and rutile TiO2, which coincided with a marked decrease in compressive residual stress, as well as an overlying morphologically stratified TiO2 layer. In-situ micro-cantilever experiments confirmed the structural integrity of the TiB2 phase below the coexistence zone, where no significant oxidation-induced change in fracture stress was detected, while Young's modulus decreased by ~25%. In conclusion, the pursued nano-analytics approach revealed detailed cross-sectional correlations between oxidation-related coating disintegration, microstructure, residual stresses and mechanical properties.

Structure-property characteristics of Al-Cu joint formed by high-rotation-speed friction stir lap welding without tool penetration into lower Cu sheet

Abstract In order to explore a novel approach to weaken the tool/workpiece interaction during friction stir lap welding of dissimilar materials, Al and Cu plates with 3 mm thickness are successfully friction stir lap welded without tool penetration into the lower hard Cu plate at high rotation speeds. Large-size Al-Cu coexistence zones composed of the composite-like structures and layered structures are formed at the Al-Cu interfaces for 2500 and 3000 rpm, where intermetallic phases Al2Cu, AlCu and Al4Cu9 are identified. Increasing rotation speeds to 3500 and 4000 rpm leads to the formation of thin and uniformly distributed layered structures featured by indiscernible intermetallic compounds at the Al-Cu interfaces, and significant hook-like structures are extended from the lower Cu sheets into the upper Al sheets. All joints fail along the Al-Cu interfaces during tensile shear test. The lap joints fabricated at 2500 and 3000 rpm present higher fracture loads than those produced at 3500 and 4000 rpm, owing to the more sufficient material mixing and the induced larger Al-Cu bonding areas under the pin stirring effects.

Structural evidence for the polymorphic phase boundary in (Na,K)NbO3 based perovskites close to the rhombohedral-tetragonal phase coexistence zone

The multi-phase coexistence is a technologically important concept in high-performance piezoelectric ceramics owing to the ability of achieving extremely increased electromechanical properties. However, in fact it cannot always produce desirable thermal stability of small-field piezoelectric properties relevant to the device application. In this work, a typical lead-free piezoelectric composition of (Na0.52K0.4)(Nb0.84Sb0.08)O3–0.055LiTaO3–0.025BaZrO3 coexisted with rhombohedral (R) and tetragonal (T) phases at room temperature was investigated as a case study by means of ex/in-situ synchrotron x-ray diffraction, Rietveld structure refinement and measurements of temperature-dependent electrical properties. The refined crystal structure proves to be a three-phase coexistence of R, orthorhombic (O) and T at virgin state, and evolves into the R+monoclinic (MC)+T phase coexistence at poled state owing to an electric field induced irreversible O-MC phase transition. Particularly, the field induced MC phase can stably exist and maintain its concentration as long as the annealing temperature is below the Curie temperature. An interesting finding is that the poled sample still retains the polymorphism of phase transition like its virgin state featuring the temperature driven R-O(MC)-T phase transition, leading to seriously degraded piezoelectric coefficients after thermal cycles due to domain de-texturing of not only MC phase, but also R and T phases during repeated phase transition. The present study would benefit to understanding of the nature of polymorphic phase boundary and the structure origin of temperature-dependent piezoelectric properties in R-T coexisted (Na,K)NbO3-based lead-free solid-solution ceramics.

Numerical modeling of methane hydrate accumulation with mixed sources in marine sediments: Case study of Shenhu Area, South China Sea

The natural gas hydrates detected in Shenhu Area, South China Sea are considered to have great potential for exploitation and to become a research hotspot. However, details of the dynamic accumulation and evolution processes of gas hydrate over a long time in this area remain unclear. In this study, we developed a numerical model to predict the accumulation of gas hydrates in the marine sediments by introducing the biogenic methanogenesis module to the framework of the existing simulator TOUGH+HYDRATE. A one-dimensional dynamic model was applied to reproduce the formation of gas hydrate at site SH2 in Shenhu Area. The burial of sediments and associated phenomena (e.g., evolution of temperature, sediment compaction and consequent reduction in sediment porosity and permeability, fluid expulsion) are taken into account. Modeling results indicate that with the conventional conversion coefficient (CC) of organic carbon to methane of 0.15, the amount of in-situ biogenic methane is not sufficient to form the highly saturated hydrate detected at this location and the remaining methane (91.4%) is supplied by the upward flow of fluids. The tectonic movement that took place about 1.5 Ma created pathways for the fluids to migrate vertically. The pore water and methane gas fluxes in the upward fluids were determined as 2 × 10−10 kg/s·m2 and 1 × 10−11 kg/s·m2, respectively, using the proved hydrate saturation profile and measured pore water chlorinity from recovered core samples. The distribution of hydrate in the sediments is significantly influenced by pore water salinity. The inhibitory effect of salt on hydrate formation, which shifts the pressure of three-phase (i.e., solid hydrate, methane gas and pore water) equilibrium to actual pore water pressure, could be the major reason for the appearance of a three-phase co-existence zone in the hydrate concentrated zone. Additionally, the water flux and diffusivity of salt have a profound effect on the formation of gas hydrate by affecting the salinity of pore water in the gas hydrate concentrated zone. The results of this study are of great significance for guiding marine gas hydrate exploration and resource evaluation.

Assessment of sanitary parameters of soils in cedar stands

The article presents the results of a study of the sanitary-microbiological parameters of soils in cedar stands on the example of the Vologda Oblast of Russia. The taxation description of cedar plantations showed that both urban and Siberian cedar plantings in the urban environment and beyond are distinguished by good growth. In the studied objects, the presence of phytopathogenic fungi dangerous for trees was found in soils, such as Aphanomyces, Fusarium, Phytophthora, Pythium, Verticillium, and the presence of saprotrophic fungi with antagonistic properties, such as Mucorales, Clonostachys, Trichoderma, Mortierella, Mucor. Phytopathogenic activity correlates inversely with the activity of saprotrophs-antagonists found in the zone of coexistence. According to microbiological indicators, the diversity of antagonistic fungi with signs of high suppression indicates the well-being of the studied soil samples. Based on the sanitary-microbiological assessment in the studied cedar groves, recommendations were developed and proposed for protecting soils in the cedar stands, such as selective forest protection measures, clearing of litter, and laboratory tests to determine the toxicity of soils that affect the growth and development of cedar stands.