Source Area Research Articles

Study on the response mechanisms and evolution prediction of groundwater microbial-toxicological indicators.

This study aims to investigate the response mechanisms of groundwater microbial-toxicological indicators, specifically total bacteria count (TBC) and total coliform count (TCC), to water quality indicators and environmental conditions. Using data from a water source in the western plateau of China, a predictive model focusing on TBC and TCC was developed. An orthogonal experimental design was employed to manipulate environmental conditions such as temperature, pH, and porosity, facilitating laboratory experiments. These experiments measured pH, chemical oxygen demand (COD), oxidation-reduction potential (ORP), TBC, and TCC at varying depths and environmental conditions. Principal component analysis elucidated the mechanisms by which water quality indicators and environmental conditions affect groundwater microbial-toxicological indicators. A prediction model for these indicators in plateau regions was established based on a backpropagation neural network (BP-NN), using TBC and TCC as target variables and the newly extracted principal components as influencing factors. The results demonstrate that environmental conditions and water quality indicators primarily influence the evolution of groundwater microbial-toxicological indicators by altering the ionic charge quantities, redox conditions, and temperature of the groundwater. The predictive model for groundwater microbial-toxicological indicators shows trends consistent with experimental outcomes, with an average relative error of less than 15%, meeting engineering requirements. PRACTITIONER POINTS: The values of total bacteria count (TBC) and total coliform count (TCC) under different conditions were obtained by column experiments. The influence mechanism of environmental conditions and groundwater indicators on TBC and TCC was elaborated by principal component analysis. TBC and TCC prediction models were established through the investigation of water sources in a plateau area and laboratory experiments.

Supply and demand analysis and security pattern optimization of flood regulation ecosystem services adapted to the complex terrain of coastal estuaries: A case study in Xiamen

The flood risk in coastal areas has been exacerbated by global climate change. Research on flood risk assessment is emerging from the perspective of supply and demand for flood regulation ecosystem services (FRES). However, there are still limitations in the evaluation of lowland regulation, implementation of intelligent algorithms, comparison of multi-grain FRES supply and demand, and overall optimization of security pattern. Therefore, we propose a comprehensive FRES supply assessment method that incorporates soil and vegetation, lowland, and water regulations. Additionally, we introduce the random forest model to enhance the FRES demand assessment approach. Two grain sizes of the sub-catchment area and grid unit are used to compare FRES supply and demand. Using Xiamen as a case study, this research unveils the following findings: (1) Significant disparities exist between the assessment outcomes of FRES based on multiple types of regulatory services and those solely considering soil and vegetation regulation. The areas with high FRES supply extend beyond upper mountain forests to include local lower plains exhibiting strong capabilities for lowland or water system regulation. (2) Consistent yet distinct results are observed when comparing two grain sizes. Imbalances in supply and demand occur in estuaries, bays, and densely built-up regions. Sub-catchment units exhibit wider distribution and concentration, while grid units display more dispersed patterns. (3) In terms of in-situ regulation, 26.77 km2 ecological protection area, 9.85 km2 ecological restoration area, and 119.59 km2 construction land flood control intervention area are demarcated. From a directional regulation perspective, 22 FRES corridors connecting source and sink areas along with 24 pinch points are identified. Optimizing security patterns through coordinated management of FRES supply and demand can enhance the resilience of coastal estuaries.

Iron redox shuttling and uptake by silicate minerals on the Namibian mud belt

Anoxic marine sediments represent an important source of bioavailable iron (Fe) to the ocean. The highest sedimentary Fe fluxes are observed in open-marine oxygen minimum zones where anoxic bottom waters are in contact with ferruginous surface sediments. Here, sedimentary Fe release, transport and re-deposition (i.e., Fe shuttling) may generate a lateral pattern of sedimentary Fe enrichment and depletion, which can be used to trace redox-related Fe mobility in the paleo-record. However, depending on the balance between terrigenous and authigenic (i.e., shuttle-related) Fe flux, the stability of bottom water redox conditions as well as post-depositional processes of mineral alteration, the sedimentary fingerprint of an Fe redox shuttle may be obscured and difficult to identify.We investigated sedimentary Fe cycling along two transects across the Namibian mud belt with variable terrigenous sedimentation (23°S < 25°S) and during two seasons with opposing bottom water redox conditions (oxic in austral winter versus anoxic to sulfidic in austral summer). On both transects, substantial benthic Fe fluxes up to −50 µmol m−2 d−1 were inferred based on pore water profiles. The magnitude of these fluxes is comparable to those reported for other open-marine oxygen minimum zones. On the transect at 23°S, Fe source areas with ferruginous surface sediments were clearly separated from Fe sink areas with highly sulfidic surface sediments. Therefore, Fe redox shuttling was reflected by a lateral pattern of reactive Fe depletion and enrichment relative to the terrigenous background sedimentation. By contrast, on the transect at 25°S, benthic Fe fluxes were temporally and spatially more variable and surface sediments were ferruginous or only weakly sulfidic. Therefore, sedimentary Fe depletion and enrichment was less pronounced at 25°S. In the Fe sink area at 23°S, hydrogen sulfide was present at the sediment surface during both sampling campaigns and solid phase data suggest that Fe sulfide minerals represented the main burial phase of reactive Fe. By contrast, at 25°S excess Fe was associated with potassium (K) rather than reduced sulfur. While a differing sediment provenance cannot be ruled out entirely, combined evidence from pore water silica profiles, K to Fe stoichiometric relationships and electron microprobe images suggest that laterally derived excess Fe was incorporated into pre-existing and/or authigenic clay minerals during early diagenesis. Iron uptake by clay minerals may be supported by frequent redox oscillations and sediment mixing preventing preservation of Fe sulfide minerals and promoting Fe and K fixation in clay minerals. The burial fluxes of excess Fe associated with sulfide minerals at 23°S and silicate minerals at 25°S were similar. Our findings thus underscore that neoformation or alteration of silicate minerals can be important processes within the low-temperature marine Fe cycle.

Contrasting orbital rhythms preserved in loess grain-size records across the Chinese Loess Plateau

The loess-paleosol sequences on the Chinese Loess Plateau (CLP) are among the best terrestrial archives for recording orbital-scale global paleoenvironmental and East Asian monsoon changes during the Quaternary Period. Dust provenance and climate patterns vary across the CLP due to its vast size. However, whether available climate proxies were influenced by varying signals from the different dust source areas remains unknown. Here we present time series analysis results of high-resolution grain-size records from four loess sections (Jingbian, Xifeng, Baoji, and Weinan sections) spanning a north to south transect in the eastern CLP across the past 0.7 Ma. By comparison with data from the previously reported Luochuan section in the eastern CLP, and the Gulang, Menyuan, Jingyuan, Lanzhou, and Linxia sections in the western CLP, it is revealed that the dominant orbital signal in grain size variations in the eastern CLP is the ∼100-kyr ice-age cycle, with precession only very weakly expressed. By contrast, western CLP records exhibit both ∼100-kyr and ∼ 20-kyr precession cycles. We show that this contrasting orbital patterns between the eastern and western CLP are likely to be influenced by the climate signals from the respective source regions. We propose that the grain size variations in the western CLP not only contain the ∼100-kyr ice-age related winter monsoon cycles but also precession cycles related to the mid-latitude Westerlies and the Tibetan Plateau. The grain size variations in the eastern CLP are, by contrast, mainly influenced by ∼100-kyr ice-age cycle-regulated winter monsoon changes. The spatial diversity of periodicity in loess grain-size records from the CLP suggests that caution should be taken when discussing the periodicities of loess records based on any single site.

Fault strength, healing and stability in the Nankai Trough accretionary prism off Kii Peninsula, Japan, as illustrated by friction experiments on gouge of a cored sample

In order to investigate fault strength, healing and stability in the Nankai Trough accretionary prism off Kii Peninsula, Japan, we conducted two series of triaxial friction experiments on gouge of a silty-claystone sample cored from 2183.6 mbsf (meters below seafloor) at IODP Site C0002, at confining pressure (Pc), pore-water pressure (PH2O) and temperature (T) conditions simulating those in situ at 1000–6000 mbsf there; rate-stepping tests at axial displacement rates (Vaxial) changed stepwise among 0.1, 1 and 10 μm/s, and slide-hold-slide tests at Vaxial = 1 μm/s with hold time (th) ranging from 10 to 104 s.Experimentally determined steady-state and static friction coefficients, μss and μs, respectively, and the log-linear th dependence of frictional healing, β, exhibit a decrease with simulated depth down to 3000 mbsf at which condition T was 100 °C, followed by an increase toward 6000 mbsf. On the other hand, the rate dependence of μss, a – b, gradually decreases with simulated depth, changing from positive at ≤4000 mbsf through ~0 at 5000 mbsf to negative at 6000 mbsf at which condition stick slips were observed.Our experimental results suggest the presence of a low fault-strength and weak fault-healing zone at ~3000 mbsf beneath IODP Site C0002, possibly due to elevated pore pressure induced by smectite dehydration. This zone correlates well with the previously reported low seismic-velocity zone and the source area of very low-frequency earthquakes to the south. Our experimental results also suggest that faulting beneath IODP Site C0002 is stable and aseismic at ≤4000 mbsf, transitional at 5000 mbsf, and potentially unstable and seismic at 6000 mbsf. In fact, stick slips corresponding to seismic faulting were observed at the 6000 mbsf condition. This implies that faulting along the plate-boundary thrust located at ~5200 mbsf beneath IODP Site C0002 is potentially seismogenic.

Hybrid multiscale computational approach for heat transfer in GaN semiconductors

Abstract With ongoing advancements in semiconductor technology, understanding thermal transport in semiconductor devices—where phonons are the primary charge carriers—is crucial. This involves a multiscale process in which phenomena at different scales are governed by distinct control equations, necessitating various numerical methods. In this context, this paper introduces a novel multiscale simulation method called the Second-Order Reconstruction Operator Finite Difference Lattice Boltzmann Method (ROsFDLBM). This method effectively combines the Lattice Boltzmann Method (LBM) with the Finite Difference Method (FDM). ROsFDLBM employs reconstruction operators to accurately map the relationship between distribution functions and macroscopic physical quantities, significantly reducing errors caused by the transmission of interface information. The efficacy of this coupling scheme has been confirmed through an interface-coupled thermal diffusion model. Comparative analyses have revealed that the relative error of ROsFDLBM does not exceed 1.2%, demonstrating its superior accuracy. Further simulations of GaN devices have confirmed that traditional macroscopic methods tend to underestimate the temperature in the heat source area at micro-nano scales, with discrepancies reaching up to 60.9 K. Overall, the ROsFDLBM aligns with current research findings and offers an accurate and efficient simulation strategy for addressing complex heat transfer problems.

Overload of dissolved organic matter (DOM) in riparian infiltration zone increasing the pollution risk of naphthalene, insight from the competitive inhibition of naphthalene biodegradation by DOM.

Riparian infiltration zones are crucial for maintaining water quality by reducing the aqueous concentrations of polycyclic aromatic hydrocarbons (PAHs) through adsorption and biodegradation within the aquatic ecosystem. Dissolved organic matter (DOM) are ubiquitous in riparian infiltration zones where they extensively engage in the adsorption and biodegradation of PAHs, thereby influencing PAHs natural attenuation potential within riparian infiltration zones. Few studies have explored the natural attenuation mechanisms of PAHs influenced by DOM in riparian infiltration zones. In this study, the natural attenuation mechanisms of naphthalene (a typical PAHs component), under the influence of DOM, were explored, based on a case riverside source area. Analysis of microbial community structures, and the electron acceptor (e.g., Fe(III), DO/NO3-, SO42-)/electron donor (naphthalene and DOM) concentration changes within the riparian infiltration zone revealed a competitive inhibition relationship between DOM and naphthalene during microbial metabolism. Biodegradation experiments showed that when the concentration of DOM is higher than 4.0 mg·L-1, it inhibits the biodegradation of naphthalene. DOM competitively inhibits the biodegradation of naphthalene through the following mechanisms: (i) triggering microbial antioxidative defense mechanisms, diminishing the available resources for microbial participation in naphthalene degradation; (ii) altering microbial community structure; (iii) modulating microbial EPS composition, reducing the efficiency of microorganisms in utilizing carbon sources; and (iv) inhibiting the expression levels of downstream genes involved in naphthalene degradation. The competitive inhibition constants of DOM with concentrations of 1.0, 2.0, 4.0, 8.0, and 16.0 mg·L-1 on naphthalene biodegradation are -2.0 × 10-3, -5.0 × 10-3,1.0 × 10-3, 4.0 × 10-4, and 1.0 × 10-4, respectively. These findings enhance understanding of PAHs attenuation in riparian infiltration zone, providing a basis for assessing and managing PAHs pollution risks during riparian extraction.

Characterization of weakly nonlinear effects in relationship to transducer parameters in focused ultrasound therapy.

Focused ultrasound therapy has been widely used for the treatment of various diseases, employing different types of transducers. The focused ultrasound pressure fields inevitably exhibit nonlinear effects, which can influence the ablation region. However, the nonlinear effects exhibit noticeable variations across different applications. The characterization of the nonlinear pressure fields of ultrasound is important for the effective implementation of focused ultrasound therapy. The traditional angular spectrum method (ASM) was extended to accurately and efficiently simulate the propagation of weakly nonlinear ultrasound in heterogeneous mediums of clinical model. The nonlinear effects were further analyzed in relationship to the transducer parameters that are different in various applications. The pressure fields were simulated using the extended ASM, incorporating calculations for phase aberration in the frequency domain and magnitude compensation in the spatial domain to account for heterogeneous acoustic impedance mismatch. Validation was performed by comparison to k-Wave simulation results using two simplified clinical models, an abdominal soft tissue and a transcranial skull model. The nonlinear effects were then analyzed in relation to the transducer parameters of f-number and effective source area based on the same acoustic output power. The analysis of nonlinear effects was conducted under both homogeneous medium and the clinical models. The simulation results demonstrated a maximum error of 3.93% in the calculated harmonic pressure of the abdominal model, and a maximum error of 4.89% within the transcranial model when comparing the extended ASM simulation results to those obtained from k-Wave simulations. The characterization of the nonlinear effects reveals a strong correlation with the transducer parameters. Specifically, the results indicate that the nonlinear effects intensify with an increase in the effective source area and f-number, under the same acoustic output power of the transducer. However, the clinical model also showed an influence on the nonlinear effects in relation to the f-number. The extended ASM was demonstrated as an accurate and efficient simulation tool, and the simulation results provide a reference for evaluating the intensity of nonlinear effects in various transducer designs.

WITHDRAWN: Restoration of the ecological network structure based on the spatiotemporal changes of the wintering Grus japonensis habitat in the Yancheng coastal area

As an Asian endemic species, Grus japonensis (G. japonensis) reproduction and survival rely on natural wetland resources. G. japonensis is adept at long-distance flight, thereby displaying distinct network structural characteristics in its utilization of habitat within its range. Therefore, scientific restoration and management of the ecological network (ENs) are urgently needed. On the basis of the data of G. japonensis and environmental data, this study used the MaxEnt model, stepping-stone theory, and circuit models to analyze the spatiotemporal changes in the ENs structure of G. japonensis habitat. The primary factors influencing the habitat suitability of G. japonensis was the distance to Phragmites australis (P. australis) community. The area of ecological source areas decreased from 56,528.59 hm2 in 1987 to 14,040.20 hm2 in 2021, with the distribution range contracting from Beihuan (BH), Nanhuan (NH), Hexin (HX) and Tiaozini (TZN) to Hexin (HX). Between 1987 and 2007, there were dense ecological corridors along the coastal areas. However, by 2021, only BH and HX had dense ecological corridors between them. The node centrality of HX decreased from 900.78 in 1987 to 264.64 in 2021, with the most significant decrease between 2007 and 2021. On this basis, the expanded habitat area, the stepping stone area in 2021 and the ecological source area of 2007 with low development intensity were taken as restoration areas. The restoration areas were classified into two types based on their distribution: landing nodes and expansion nodes. The addition of landing nodes enhanced the overall stability of the ENs, resulting in an increase in the centrality of nodes from 264.64 to 398.08. Finally, an optimization and restoration framework for the habitat network based on identifying priority restoration areas, land use type transformation, and enhancing ENs stability for habitat restoration was proposed.

Ediacaran diamictite deposition in South China: Detrital zircon u-pb age evidence and macro sedimentary texture of the Aiqiling formation in southeastern Hunan Province

A better understanding of Ediacaran (Gaskiers) glaciations, including their ages, global distribution and types, is critical to our understanding of the Earth’s evolution following the Neoproterozoic “Snowball Earth”. The present study focuses on a diamictite that forms part of a continuous succession of Neoproterozoic clastic sedimentary rocks in the northwestern margin of the Cathaysia block in South China. Detailed sedimentary sequence established here shows that the diamictite, previously interpreted to be Cryogenian in age, is a part of the Ediacaran Aiqiling Formation. Detrital zircon U-Pb ages constrain its maximum deposition age to ca. 571 Ma, supporting its Ediacaran age. The macro sedimentary textures of the diamictite unit, including matrix-supported sediments with angular and randomly distributed clasts, combined with regional geochemical results, suggest a glaciogenic origin. The U-Pb detrital zircon age data also indicate an uplifting source area to the southeast that migrated northwestward since the Ediacaran.

Reliability of the Strontium Isotope Stratigraphy approach in marginal seas: Insights from the Miocene Paratethys

The robustness of the Strontium Isotope Stratigraphy (SIS) as a chemostratigraphic tool was tested in the Miocene epicontinental Central Paratethys using new 87Sr/86Sr results obtained for 129 foraminiferal tests and various marine invertebrate shells that were converted to numerical ages using the global 87Sr/86Sr curve for Phanerozoic open oceans. These ages were compared with those expected from either magnetostratigraphic, radiometric or biostratigraphic studies applied to selected sections from different Central Paratethys basins. The results from different basins showed variations in 87Sr/86Sr values for specific time intervals; therefore, it is not possible to construct a unique 87Sr/86Sr curve for the Central Paratethys region that can be used for chemostratigraphic purposes. The 87Sr/86Sr signal in semi-enclosed basins tends to reflect the lithology of the source areas. a: For example, marine basins surrounded by areas of Mesozoic carbonate rock cover are associated with a reduced 87Sr/86Sr signal compared to the global 87Sr/86Sr signal primarily due to the drainage of these Mesozoic carbonate rocks and transfer of their specific Sr signal. By contrast, areas affected by continental runoff from crystalline terrains in combination with limited connection to surrounding marine domains were found to show an elevated 87Sr/86Sr signal compared to the global one. Additionally, it was demonstrated that infaunal, eutrophic and hypoxic species (foraminiferal genus Uvigerina and molluscs) show a shift towards a relatively higher 87Sr/86Sr signal. Therefore, our data show that variable 87Sr/86Sr patterns occur in semi-enclosed domains, primarily reflecting local settings and thus hampering reliable SIS ages. In particular, the best SIS results in the studied Paratethys area occur during periods of maximum marine connectivity, when other (biostratigraphic) methods can be applied, and then become unreliable as connectivity diminishes.

Analysis of High and Low Temperature Performance of Titanium Zirconium Molybdenum Alloy and High Temperature Alloy Brazed Joint

Abstract Using niobium as the intermediate layer and gold nickel (Au82-Ni) filler metal, TZM alloy and high-temperature alloy GH3128 were brazed. The brazed specimens were subjected to 400 cycles of high and low temperature cycling tests at temperatures ranging from 650 °C ∼ 680 °C (high temperature) to -196 °C (low temperature) for 10 minutes seperately. Then the microstructure variation before and after the experiment were observed and the shear strength of the specimens were tested at room temperature for 50 cycles of 400 high and low temperature testing.. The results show that the microstructure of the transition zone at the brazing interface after brazing is uniform and dense, with good wettability with the substrate and no defects such as cracks. The solder and substrate undergo diffusion reactions, and the molybdenum alloy, niobium, and niobium, high-temperature alloy had each form diffusion layers, formed intermetallic compounds on the brazing surface. After high and low temperature cycling, cracks exist in the braze seam between molybdenum alloy and niobium alloy. The cracking mode should be thermal fatigue based on the fracture morphology and phase analysis. The reasons of interface cracking are that due to different thermal expansion coefficients, low mutual solid solubility, and the formation of a large number of different types of intermetallic compounds, Mo and Nb materials have poor brazing compatibility and lower interface strength. Under cold and hot cycling conditions, brittle intermetallic compounds are prone to form crack source areas. As the number of cycles increases, the cracks gradually expand, ultimately leading to product leakage. In addition, the shear strength of brazed joints shows a decreasing trend with the increase of high and low temperature cycles in 400 high and low temperature tests.

Геохимические и типологические особенности детритовых цирконов сосновской толщи палеогена (Русская плита)

The Paleogene Sosnov Formation is represented by glass quartz sands which are widely occurred in the eastern part of the Russian Platform. Interest in Paleogene quartz sands in Russia is increasing due to the growing needs of the glass industry. But by now, the mineral resource base of glass raw materials in the European part of Russia is of almost complete exhaustion. In recent years, the comprehensive study using modern mineralogical and geochemical methods is undertaken resulting in substantiation of the injecting mechanism of formation of Sosnov quartz sands. The current paper presents the results of the study of morphologic and geochemical features of detrital zircons extracted from the sands of the Paleogene Sosnov Formation and the Bathonian Lukoyanov Formation. The latest can be proposed as a source layer for the Paleogene sand injectites. It has been determined that zircons from both strata are of the same Pupin`s morphological types and regarded to be originated from predominantly intermediate, mafic, and rarely felsic rocks. The Puchezh-Katunk endogenous structure is suggested to be the most probable source area. The assumption that the Bathonian Lukoyanov sandstones are the most probable source for the injection of the Paleogene sands is confirmed.

The Development and Optimization of a New Wind Tunnel Design for Odour Sampling

The characterization of passive area sources, emitting odours due to wind-driven convection, poses significant challenges. The present experimental study aims to evaluate the performance, in terms of fluid dynamics and mass transfer, of a recently developed wind tunnel, with a more compact design and reduced weight, compared to the one proposed by the Italian regulations. The results show that the new design outperforms the Italian standard in several aspects. From a fluid dynamic point of view, the new wind tunnel exhibits a slightly more homogenous and uniform velocity distribution, and it does not reveal airflow preferential channels inside the central body. The pressure tests highlight that the presence of fillers in the new wind tunnel does not significantly alter the pressure inside the hood and therefore the gas–liquid equilibrium conditions; actually, the slight overpressure may help to prevent the infiltration of external air. Finally, mass transfer tests on the standard device show a vertical concentration gradient along the outlet duct, highlighting concentration values that differ up to a factor of two depending on the measurement point. The new design has almost completely solved this issue, thanks to the use of fillers that promote mixing of the outlet flow.

Mineralogy and Major Element Geochemistry of the Oligocene Barail Group Sandstones from the Sylhet Trough, Bengal Basin: Provenance and Tectonic Implications

The origin of Oligocene sediments in the Bengal Basin and associated tectonic setting remain poorly understood. This study investigates the framework mineralogy and major element geochemistry of the Barail Group sandstones from the Sylhet Trough within the Bengal Basin to clarify the provenance and tectonic history of the Oligocene. Modal analysis (Q83F7L10) and geochemical data support a classification of sublitharenite to subarkose, some with Fe enrichment. The heavy mineral assemblage is dominated by opaque minerals, followed by ultrastable minerals with zircon &gt; tourmaline &gt; rutile. The sub-angular to sub-rounded sand grains with a compositionally moderate mature nature suggest that the sediments were deposited close to the source area. The mineralogical and geochemical provenance discrimination diagram suggests contributions from felsic igneous, sedimentary/metasedimentary, and low-grade metamorphic sources, with detritus derived from the Indian craton and proto-Himalaya region. Data suggest moderate to intense chemical weathering, indicative of low relief and a sub-humid to humid climate in the source area. The tectonic analyses indicate that the Bengal Basin transitioned from a predominantly passive margin to an active tectonic margin setting during the Oligocene.

Petrography of Ophiolitic Detritus from a Miocene Conglomerate Formation on Darnó Hill, SW Bükk Mts (N Hungary): A Unique Tool to Trace Covered Ophiolitic Sequences

Petrographic studies have been carried out on the Early Miocene Darnó Conglomerate Formation, which consists only of debris of ophiolitic mélange and is found today on Darnó Hill in SW Bükk, NE Hungary. The studied sediments are bounded by the Darnó line from Darnó Hill. The aim of this work was to show if it is possible to reconstruct the petrographic composition of the source area only from its debris. The rock types were determined in thin sections using a polarizing microscope, and a quantitative analysis of the different rock types was carried out using the grain counting method, the results of which were interpreted as volume ratios. The main rock types observed in the studied samples (textural varieties of basalt, dolerite/microgabbro, claystone, siltstone, and radiolarite) are similar to the rock types of the mélange assemblage of Darnó Hill. Based on the volume calculations of basaltic detrital grains with different textures characteristic for pillow basalts, it could be established that pillow basalts dominated the igneous rocks in the source area of the Darnó Conglomerate on Darnó Hill already in the Miocene. Thus, this work shows that the lithological composition of a source area can be precisely outlined by a detailed petrographic analysis of the debris eroded from the immediate vicinity.

Impact of precipitation change in the Yangtze River source area on groundwater from the perspective of ground-based and satellite-based observations

In the context of global climate change, the hydrological cycle of the Yangtze River source area has produced significant changes. It is of great practical value to study the influence of regional precipitation changes and precipitation events on regional water resources, especially groundwater. This study uses base flow segmentation and GRACE groundwater reserve calculation technology to examine precipitation’s spatial and temporal variation, especially extreme precipitation events, in the Yangtze River source area. The events analyzed were the extreme precipitation-runoff-base flow response from the Yangtze River source, the extreme precipitation-terrestrial water (surface water and groundwater) response, and the comparison of these events. The findings indicated that extremely strong precipitation, maximum precipitation for five consecutive days, days of moderate rain and above moderate rain intensity precipitation, the longest number of precipitation days, and other extreme precipitation indices had a significantly increasing trend and increased intensity of extreme precipitation events, the regional differences in precipitation trended less significantly. The base flow index gradually increased at a rate of 0.0014 yr-1, suggesting the overall increase of water resources and the contribution rate of groundwater to the runoff was an increased trend . There is a high correlation between the change of water resources in the source area and the change of precipitation, and the increased precipitation influenced an increase in groundwater and regional water resources. These findings inform current knowledge of precipitation-groundwater response mechanisms in alpine and arid regions such as the Qinghai-Tibet Plateau.

Modern Drip Irrigation Technology on Tomato and Head Cabbage Production and Its Economic Feasibility at Misrak Silti District, Siltie Zone, Ethiopia

In Ethiopia various techniques were applied to improve on-farm irrigation water management under surface irrigation, especially on furrow irrigation system for last many years, however, it was very difficult to achieve threshold limit of water use efficiency, wisely use of scarce water resources in irrigated field, crop water productivity, precisely controlled application of irrigation water to plant roots, uniform water delivery to all plants, crop yield and its quality, regulate flow, deliver optimum crop water requirement, field water losses, groundwater withdrawal and save labor. It is great practical significance and series of measures using drip irrigation system to solve mentioned problems in irrigated field, because the irrigated agriculture is largest water-consuming sector in this area. This study was aimed to demonstrate drip irrigation technology, prove its economic feasibility and create skills of farmers and extension experts on implementation of the drip system on tomato (Galila 555) and head cabbage (Copen Hagen) productions within groundwater source area on Balo koriso main station in Misrak Silti woreda, Siltie zone, southern Ethiopia. The activity was done for four consecutive years (2019 to 2022 G. C) on fixed plot of 2500 square meter area in collaboration with Agricultural Research Institute and Techno serve project. During demonstration all the costs were considered to economic feasibility including initial investment cost. The study found that the use of drip irrigation saved 3690 m&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;/ha of water compared with use of furrow irrigation. This saved water may irrigate additional 2ha area of land by drip irrigation. This study also revealed that, a net income of 313066.04 ETB/ha in single irrigation season was obtained using modern drip irrigation technology. The farmers and local experts recognized noticeable saving water, fuel cost, irrigating time and labour, good crop performance from demonstrated drip irrigation system and shown interest to use the technology abundantly. Therefore, scaling up locally manageable drip irrigation system around the study area through comprehensive training of farmers and supportive staffs and allowing sufficient local market for drip kits and incentives or loan will be economically feasible and affordable to increase income and saves irrigation water.

Provenance of mineral dust deposited on Antarctica over the last sixty years by strontium isotopic analysis of snow from Dome C

The strontium (Sr) concentration and 87Sr/86Sr isotope ratio have been determined in 132 snow pit samples collected at Dome C, on the East Antarctic Plateau, corresponding to the period 1958–2019, and in 12 surface snow samples collected at the same site in 2016–2017. The average Sr concentration was 8.1 ± 5.7 pg g−1 (mean ± SD) in snow pit samples and 10.1 ± 8.0 pg g−1 (mean ± SD) in surface snow, without any significant temporal trend. The 87Sr/86Sr isotope ratio showed small variations (<0.15%), with an average 87Sr/86Sr value of 0.7094 ± 0.0010 (mean ± SD) in snow pit and 0.7103 ± 0.0004 (mean ± SD) in surface snow samples. These results seem to suggest that no change in the source(s) of mineral dust has occurred throughout the period investigated.Comparison of the 87Sr/86Sr isotope ratio of the snow samples with those of potential source areas suggests that the mineral dust reaching the East Antarctic plateau over the last decades is of a mixed origin, with a contribution from Patagonia and one or more other source(s) having a more radiogenic Sr isotopic signature, with a major fraction coming from South Australia.

Interior noise characteristics, source identification and its quantification contribution of 400 km/h high-speed train in different operating environments

Noise level is one of the core technical indicators of high-speed trains, especially for a speed of 400 km/h. Noise source identification and its contribution quantification are key for interior noise control. This article takes a certain high-speed train running up to 400 km/h as the research object. Firstly, based on the interior noise spectrum and experimental results of source identification based on spherical harmonic function, the main source locations and energy distribution inside the train are determined. Secondly, through polynomial fitting, the correlation between vibration and noise in various areas inside and outside the train and speed is determined. Subsequently, by calculating the energy contribution through area integration, the noise contribution of each interior region is determined, and then the variation law of the noise contribution of each region with the speed is determined, and the quantitative contributions of various areas inside the train are given when the high-speed train is running at 400 km/h. Finally, the vibration and noise inside the train, aerodynamic noise on the train body surface, and noise in the bogie area in open lines and tunnel operating environments are compared and analyzed, as well as their variation laws with speed. The main noise sources inside the train under two types of operating environments are identified, and the contribution rates of noise sources in different areas inside the train are analyzed, further studying the interior noise and vibration transmission characteristics. The results show that, when the high-speed train is running at 400 km/h in open line operating environment, the significant frequency range of interior noise is 40 Hz ∼ 2000 Hz, and dominant interior noise sources are located in the roof and floor. In the tunnel operating environment, the significant frequency range of interior noise is 160 Hz ∼ 1000 Hz, and the primary sources of interior noise are predominantly located in the left window and floor. For the sidewall area, the interior noise comes mainly from the vibration of the inner sidewall when in open line operating environment, while in tunnel operating environment, the interior noise comes mainly from the aerodynamic excitation of the body surface.