Sandy Zones Research Articles

Riparian restoration in sandy zones with alfalfa as pioneer plant in initial stage of soil and water bioengineering

As Nature-Based and Bio-based Solutions, soil and water bioengineering (SWB) provides several benefits to humans and nature. It has been widely used for erosion control, vegetation recovery and ecosystem restoration in riparian zones. Nevertheless, studies on riparian restoration in sandy zones with alfalfa as pioneer plant in initial stage of SWB are still rare, which are important for understanding the role of pioneer plants during the initial stage of SWB and also for choice of the appropriate measures. Here, three commonly applied SWB measures (vegetation geobag / VGB, grass-planting concrete block / GCB, and untreated flat area / NTF) are established in sandy riparian zones to explore the growth characteristics structural mechanics and reinforcement of pioneer plant (alfalfa) root, and also the factors influencing biomechanical properties in initial stage of SBE. Our results show that: (1)NTF demonstrated superior overall growth compared to GCB and VGB, underscoring the limitations that geobags and steep slopes impose on initial SWB vegetation establishment. In all treatments, alfalfa roots were able to penetrate soil layers below 60 cm, with NTF exhibiting the highest root biomass and diameter (NTF > GCB > VGB). GCB's higher root-to-shoot ratio may reflect a drought-resistant strategy. In contrast, VGB showed greater root length, maximum rooting depth, and a smaller crown width, indicating a focus on root growth to overcome geobag constraints (2) Differences in root growth distribution among the three treatments resulted in varying biomechanical impacts. Specifically, NTF exhibited significantly lower soil-root bond strength than GCB, while both NTF and GCB had higher maximum pull-out forces compared to VGB. Root diameter showed a significant negative correlation with Young's modulus and root tensile strength, but a positive correlation with root tensile force (p < 0.05). Although no significant correlations were found between root water content and root tensile strength, root tensile strength was positively correlated with Young's modulus. (3) In the comprehensive evaluation of root reinforcement performance, the scores ranked as VGB > GCB > NTF. Result of this study could provide valuable insights into the practical applications of SWB in sandy riparian restoration. Furthermore, it underscores the importance of pioneer plants in the fragile and critical initial stages of SWB, and also benefit both researchers and practitioners in effectively transitioning from the scientific research to practical solutions for riparian restoration.

Reduction capacity in the transmissive zones fueled by the embedded low-permeability lenses: Implications for contaminant transformation in heterogeneous aquifers

Redox conditions play a decisive role in regulating contaminant and nutrient transformation in groundwater. Here we quantitatively described and interpreted the temporal and spatial variations of aquifer reduction capacity formation in lens-embedded heterogeneous aquifers in 1-D columns. Experimental results indicated that the aquifer reduction capacity exported from the low-permeability lens permeated into the downstream sandy zones, where it subsequently accumulated and extended. Reactive transport modeling suggested that reduction capacity within the lens preferentially diffused to the transmissive zones around the lens-sand interface, and was then transported via convection to downstream transmissive zones. A low-permeability lens of the same volume, but more elongated in the flow direction, led to less concentrated reduction capacity but extended further downgradient from the lens. The increased flow velocity attenuated the maintenance of aquifer reduction capacity by enhancing mixing and diluting processes in the transmissive zones. The reduction zones formed downstream from the low-permeability lens were hotpots for resisting the oxidative perturbation by O2. This study highlights the important role of low-permeability lenses as large and long-term electron pools for the transmissive zones, and thus providing aquifer reduction capacity for contaminant transformation and remediation in heterogeneous aquifers.

Strengthening of the railroad track for high-speed traffic on the Bukhara-Misken section

In the article the work of ballast prism and subgrade is considered, on the basis of analysis two-layer reinforcement from geotextile is offered, also strengthening by water-soluble polymer in conditions of sandy zone on high-speed sections of railroads is suggested. The principle of stationarity of the total potential energy of deformable Lagrangian systems is used to determine the stress-strain state of the earth bed. The dependences between the components of stress and strain tensors characterizing specific models of the medium have been established, and an elastic ground medium with no residual deformation from external load has been considered. And also offer designs of sleepers with concave surface, which will increase the service life and ensure the reliability of its operation on horizontal and vertical curves of railroads. A new fluoroplastic under-rail gasket, which does not change its characteristics during 5 years, contacting with the base of the rail, flat inner support surface, contacting with the sleeper, reduces load vibration from the rolling stock on the sections of high-speed traffic is offered.

Composition and Content of Carotenoids of Gastropod &lt;i&gt;Tritia reticulata&lt;/i&gt; in Black Sea

The results of a two–year study of the composition and content of carotenoids of sea snails Tritia reticulata (L., 1758), living in a mixed bottom community of bivalve mollusks in the sandy zone of the upper sublitoral (depth 0–1 m) of the Cossack Bay of Sevastopol, are presented. The highest content of total carotenoids was detected in June (1.8–2.09 mg/100 g of crude mass), the average Cossack Baymples for both years was 1.54 mg/100 g of crude mass. In the qualitative composition of T. reticulata taken from the pastures of bivalves on sandy-silt soil, 15 free carotenoids were identified: b-carotene, echinenone, hydroxyechinenone, astaxanthin, didehydroastaxanthin, diadinoxanthin, diatoxanthin, fucoxanthin, halocintiaxanthin, fucoxanthinol, mactraxanthin, heteroxanthin, lutein, zeaxanthin, alloxanthin and esters of the last 4 carotenoids. The po-ssibility of metabolic transformations of carotenoids is discussed.

ECHINODERM COMMUNITY STRUCTURE IN TAMBA BEACH, NORTH MINAHASA REGENCY, NORTH SULAWESI PROVINCE

Tamba Beach has several ecosystems, namely seagrass beds, sandy and rocky. Ecologically, seagrass beds are home to marine life, including Echinodermata. Echinoderms play an important role as an integral part of the food chain, eating organic waste. The purpose of this study was to analyze the community structure of Echinoderms at Station I (Seagrass Zone), Station II (Sandy Zone) and Station III (Coral Zone). Two methods are used in this study. The first is a qualitative description method by directly observing and quantitatively calculating the diversity index, uniformity index, dominance and abundance index formulas. The echinoderms found consisted of 4 classes, namely Holothuidea, Ophiuroidea, Echinoidea and class Asteroidea. The echinoderms found at the study site used a diversity index classified as stable. The dominance index is low because there are no dominant individuals, and the uniformity index is low. From the results obtained from the abundance in Tamba Beach, the highest value was in the Diadema setosum species with 113 individuals. Diadema setosum has the highest quantity at the three existing stations. This species can adapt to environmental changes.

Spatial and Temporal Evolutionary Characteristics of Vegetation in Different Geomorphic Zones of Loess Plateau and Its Driving Factor Analysis

Based on MODIS NDVI and a meteorological dataset, this study analyzed the spatial and temporal variation characteristics of vegetation cover in different geomorphic zones of Loess Plateau (LP) from 2000 to 2020 with trend analysis, partial correlation, residual analysis and the CA–Markov method and discussed the driving factors. The research results show that: (1) There are spatial differences in vegetation coverage in different geomorphic regions. The Loess Hills and Forests zone (LF) exhibits the highest coverage, with a multi-year average of 86.64%, and the Arid Grassland (AG) has the poorest vegetation with only 8.53%. Overall, there has been significant improvement in vegetation coverage over the past two decades, although certain geomorphic zones, particularly the Highland Steppe zone (HS) and Alluvial Plains zone (AP), show signs of degradation. (2) Relative humidity has the greatest impact on vegetation among the three climate factors, i.e., relative humidity, precipitation and temperature. Relative humidity predominantly promotes vegetation in all geomorphic zones. Temperature generally inhibits vegetation growth, except in the Wind Sandy zone (WA) and AG. The impact of precipitation on vegetation depends on the region. A lag effect is observed, with temperature and humidity showing a one-month lag and precipitation showing a two-month lag on vegetation response. (3) Human activities play a crucial role in promoting vegetation, particularly in the WA zone, in which the percentage of area where human activities contribute to vegetation has changed from 13.80% to 86.85%, an increase of 73.05%, while the HS experiences an inhibitory effect due to overgrazing and water resource overutilization. Similarly, the AP zone’s vegetation growth is hindered by urban development and land use changes. (4) Land use change significantly impacts vegetation dynamics on the LP. Over the past two decades, the area of forest lawn increased by 122,800 km2, which is 1.5 times more than the area of reduction. However, conversion to building land has hindered vegetation growth in certain regions. A comprehensive strategy is required to conserve land resources and promote healthy vegetation growth on the LP.

Shallow Water Flows (SWF) evaluation by 3D seismic studies in the South Caspian Basin, Iran

The South Caspian Basin (SCB) is known as one of the World's deepest and largest hydrocarbon-prone basins. Due to high subsidence and sedimentation rate in this deep-water basin, many overpressure sandy zones are susceptible to shallow water flow (SWF) problem. SWF is one of the geological hazards in deep-water exploratory drilling such as SCB. When the drill reaches the SWF zones, sands and water flow into the wellbore which cause the drilling failure. Therefore, the present study is the first detailed evaluation of SWF problem predrilling in the SCB, offshore Iran by using 3D post-stack, pre-stack seismic data and log data. Seismic attributes have been applied to identify the buried channels which may be considered as the most potential feature for SWF occurrence. Simultaneous inversion has been used to extract the parameters such as P-impedance (AI), S-impedance (SI), Vp/Vs ratio, Poisson's ratio. Based on inversion results, unsupervised artificial neural networks also used to estimate the probability of SWF risk in the buried channel for the first time. Our initial evaluations based on the similarity and sweetness attributes indicated that some buried shallow sandy channels with a variable width between 500 and 1500 m covered by imperious clay layers are the most potential facies for creating the SWF zones in the SCB. The SWF zone is detected by low-impedances (AI<3150 (m/s)*(g/cc), SI < 1500(m/s)*(g/cc), high Vp/Vs ratio (1.21 to 2.23) and Poisson's ratio in range of 0.05 to 0.38. The probability of SWF risk of the detected channel is estimated to be >0.35 by unsupervised artificial neural networks. Finally, our findings provide a new comprehensive evaluation of SWF problem in the channel system predrilling in the SCB which may be useful for other researchers and decrease the drilling risk in future works.

Design and implementation of an innovative wind power system for beach erosion protection and nourishment

Beach erosion phenomena have become increasingly frequent and devastating with serious economic damage on tourism. A relatively recent technique of beach protection and nourishment is based on the creation along the shoreline of an unsaturated sandy zone, in which the level of the phreatic surface is lowered by means of buried drains connected to electric suction pumps. The main problem encountered in this solution is the need to guarantee the drainage when the erosive activity is maximum in the presence of intense thunderstorms that often produce malfunction and outage problems of the power supply. This paper shows the realization of a “green” solution based on a totally mechanical design and construction approach, achieved by connecting a 3.5-meter single-bladed wind turbine to a submerged axial pump with optimized volute by means of a vertical shaft placed inside the tower. The system is managed by a mechanical pitch controller studied for starting and limiting power in exceptional winds.

Determining Nest Site Selection by Hawksbill Sea Turtles in the Persian Gulf Using Unmanned Aerial Vehicles

Nest site selection is an important aspect of reproductive behavior in sea turtles, and it is influenced by biotic and abiotic beach characteristics. To date, the association between nesting beach characteristics and nest site selection has been explored manually at small scales; yet, hawksbill turtles (Eretmochelys imbricata) nest on a variety of beaches, with knowledge remaining limited on preferred habitat. Here, unmanned aerial vehicles were used to assess all available beaches, identify common characteristics, and determine the preferred nesting sites for hawksbill turtles in the Persian Gulf. High resolution photographs were taken of 236 nests with unmanned aerial vehicles on 7 main islands supporting 10 nesting beaches. The physical characteristics of these nests were photographed (e.g., elevation, slope, vegetation cover, and nest distance from vegetation and the high tide line). Slope was the most important factor regulating nesting activity. Most turtles nested on shallow-sloped beaches with 5° slopes or less (61.4%), at a distance of ≤ 15 m from the high tide line (71.8%), and generally ranged from 1 to 3 m (83.9%) above sea level. Most nests (87.7%) were laid close to the vegetation line (≤ 5 m) in sandy zones. Although there was high geomorphological diversity in landform among the islands, nesting habitat characteristics of hawksbills were consistent. Unmanned aerial vehicles provide a useful approach for identifying the nesting habitat preferences of sea turtles in a time- and cost-efficient manner, covering more surface while minimally disturbing fragile habitat.

Evaluation of grain size distribution of Wadi As Suqah, Northeast of Jeddah, Saudi Arabia

Wadi As Suqah, Makkah Governate, Western Saudi Arabia, has surficial sediments covering 300-422 square kilometers. The deposits may be used for any suitable construction material. Therefore, thirty-one samples of the Quaternary sands were collected from different locations along the study area to achieve this goal. The natural surficial grain sizes of Wadi As Suqah deposits in the Makkah region were assessed geotechnically, spatially, and mathematically. Rarely comprehensive exploration methodology, such as sieve analysis, 3D modeling, triangulation, and GIS, have been used to categorize the content percentage of grain sizes. Statistics and mathematics were also used to evaluate the correlations and assess the relationship between the fractions. This sophisticated approach is adapted for the first time on Wadi As Suqah, which concludes different results compared to previous studies. According to the unified soil classification system, gravel, sand, and fine had an average content of 85.1%, 11.7%, and 3.2%, respectively. Therefore, Wadi As Suqah, based on the fractions percentage, is categorized into four spatially sandy zones. At a coefficient of determination, R²=0.98, sand, and fine have a linear relationship. The major mathematical model is y=-1.02 x+100.5, in which y is the fine % content, and x is the sand % content. It can be merged with mineralogy for future studies to evaluate sediment from a geological engineering point of view.

Zoning of coastal environments based on sediment textural and geochemical characteristics and their major oceanographic constraints: A case study in South Korea

• Coastal zoning aids environmental impact assessment. • Sediment textural and geochemical properties are key characters affecting zoning. • This ( Ahn et al., 2001 ) study applies sediment characters to science-based marine spatial planning . • The South Korean coast can be scientifically divided into three zones. The three zones partly coincide with the previous arbitrarily categorized blocks. • A primary factor constraining the zoning in this case study is tidal range . To assess the environmental impacts of offshore wind farming and sea sand mining, coastal areas are zoned on the basis of their natural oceanographic characteristics. Textural and geochemical properties of South Korean coastal sediments, including mean grain size (Mz), CaCO 3 and organic-matter contents, and metal concentrations (Al, K, Ba, rare earth elements, Zr, etc.), were analyzed and categorized in this case study, practically applying common sediment properties for rational zoning of the South Korean coastal environment. Three characteristic zones are scientifically classified in the study area, although four groups of sediment sampling stations were statistically clustered based on their major sediment properties. Zone 1, in the northwestern part of the Korean west coast, is characterized as covered with coarse-grained sediments containing low concentrations of the measured elements under a macro-tidal regime (6.5–9 m), while Zone 3 is characterized by fine-grained sediments with high elemental concentrations under a micro-tidal regime (>3.5 m). Silty Zone 2 sediments appear to be a mixture of sandy Zone 1 and muddy Zone 3 sediments under a meso-tidal regime. The difference in tidal forces among the zones is proposed as a primary constraint of overall sediment textural and geochemical characteristics, while sediment provenance provides subsequent control. Sediment contamination with anthropogenic pollutants is unperceivable in this case study. However, the K and Li concentrations in coarse-grained feldspar and fine-grained illite, respectively, are likely not limited by the tidal flow regime.

Characterization of Genetic Diversity in Dhofari Wild Gazelles

Wild gazelles are scattered in most of the arid and semi-arid areas of the Sultanate of Oman particularly in valleys, mountains and sandy zones of Rub' al Khali desert. Recently, gazelles’ populations have been facing reduction in the numbers. Consequently, gradual loss of genetic diversity is inevitable. This loss is considered one of the main threats that attribute to a loss of habitat and may lead to gazelle extinction. Till now, little is known about the status of the genetic diversity of the wild Dhofari gazelle. This project aimed to determine the extent of inbreeding, population structure and genetic diversity in the Dhofari gazelles’ populations. DNA was extracted from gazelles’ fecal samples using the human stool DNA extraction protocol. Following extraction, four microsatellite nuclear markers were used to calculate the level of inbreeding, population differentiation and genetic diversity. PCR inhibitors were significantly removed by the addition of Bovine Serum Albumin (BSA) and dimethyl sulfoxide (DMSO). The mean inbreeding for the population was 0.228 for all loci with a standard error of 0.09. It is therefore postulated that Dhofari gazelles are generally undergoing gradual inbreeding which could lead to lack of fitness in future generations. The genetic differentiation (Fst) ranged between 0.071 (between Gara and Stom) and 0.231 (between Gara and Ayon). On the other hand, the Fst estimate between Solot (most distant) versus other Dhofari gazelles populations (pooled together) was 3.7%. Principle Components Analysis clustered Ayon and Gara populations apart from one another and closer to Stom while placing Solot further than all other populations which is in agreement with the Fst results and the geographical distribution. In conclusion, the results of this preliminary study will provide insight towards the conservation of wild gazelles in Dhofar. This is the first study to report the genetic diversity and status of wild Gazelles and provides a reference point for future studies assessing their genetic diversity and variability.

RESEARCH OF BATYRBEK MOUNDS ON NARYN SAND

The article presents the results of archaeological excavations on the Batyrbek Mound on the Naryn sand. The Naryn sands are located in the northwestern part of the Caspian Basin, between the Volga and Ural rivers. Administrative covers Isatai Was Makhambet areas of Atyrau region and the southern part of Bokey Orda, Zhangala and Akzhaiyk parts of the West Kazakhstan region. The area is 40 thousand km 2. The sandy zone is on average 21 m below sea level. The region is formed by deposits of the Khvalyn and Khazar periods of the Caspian Sea. Consists of arrays Batbayar, Botany, Condulet, Manteca Arcticum, Zhamankum Horde. The north-East is occupied by the Kamyshovo-Samara floodplain. Often the wind blows, a dust storm. A river with a constant flow of no streams. Fresh water reserves underground (at a depth of 1.5-2 m) are plentiful. There are many wells and oases. The spring floodplain runoff of Karaozen and Saryozen sometimes irrigates the northern side of the Naryn sand. The soil cover consists mainly of pale brown, sandy loam, and salt-gray soils[1]. In September 2019, excavations were carried out of 2 burial grounds dating back to the Iron Age, located 3.36 km south of the village of Batyrbek, located on the north-western side of the Kurmangazinsky district of Atyrau region. In archaeological excavations, tombs typical of the Iron Age were discovered. 4 graves were discovered, buried in the late period. The article covers the research of these mounds. The mounds are found in the northwestern part of the Naryn sand, in the steppe areas of «takyr», consisting of hard clay rocks. There were hundreds of Iron Age burial mounds in these areas. The mound was excavated for the first time.

Spatiotemporal patterns of the forage-livestock balance in the Xilin Gol steppe, China: implications for sustainably utilizing grassland-ecosystem services

Understanding the spatiotemporal patterns of the forage-livestock balance is imperative for regionally arranging animal husbandry production while ensuring sustainable grassland-ecosystem service use. The Xilin Gol steppe is an important native grassland resource in Inner Mongolia Autonomous Region, China. This study aimed to elucidate the dynamics of the forage-livestock balance in the Xilin Gol steppe during the period 2000–2015. We evaluated the forage production and corresponding livestock carrying capacity (LCC) in the growing seasons of 2000–2015 using remote sensing data and field surveys. The spatiotemporal patterns of the forage-livestock balance were then assessed at regional, city (including city, county and banner), and village scales using statistical and household survey data. The results showed that both forage production and LCC decreased in the Xilin Gol steppe from east to west. During the period 2000–2015, the regional average forage production and corresponding LCC fluctuated without following a distinct trend, but were consistent with the variations in precipitation. The forage-livestock balance varied with time, space, and scale. At the regional scale, steppes were overgrazed in the early 2000s, but a forage-livestock balance or even grazing potential was achieved in other years. At the city scale, approximately half of the region exhibited a “forage-livestock balance” since 2000. However, about half of the region still experienced overgrazing, which mainly located in the southwest sandy zones. Such changes may have been affected by the variations in grassland quality, forage production, compensation payment, and so on. We suggest a location-specific management scheme for grazing constraints, ecological compensation payment, and industry development to aid in harmonizing animal husbandry and environmental restoration, while promoting sustainable development goals by 2030.

Distribution of the thistledown velvet ant (Dasymutilla gloriosa Saussure) in Baja California Sur with new records for the Gulf of California Southern Islands

This study presents the first report of the occurrence of Dasymutilla gloriosa (Hymenoptera: Mutillidae) on Carmen, Cerralvo (Jacques Cousteau), and San Marcos Islands, Baja California Sur. Additionally, we collected D. connectens and D. gloriosa on the mainland of the Peninsula at the Sierra Laguna Reserve, that corresponds to the geographical distribution of these Dasymutilla species. Several individuals were collected in the coastal dune zone and the sandy zones within the shrublands on the islands and sandy areas inside the xerophytic shrubland and deciduous forest at Sierra La Laguna. Two hypotheses were drawn about the arrival of the mutillids to the islands: 1) islands biogeographical history, and 2) anthropogenic influence.

DNA metabarcoding analysis of macroalgal seed banks on shell surface of the limpet Niveotectura pallida

ABSTRACT In macroalgal restoration on urchin barren coasts, understanding the variability in microscopic stages of canopy-forming macroalgae such as kelps and fucoids is critical to reduce restoration effort (i.e. sea urchin removal). In the present study, we used epilithic macroalgae present on the limpet Niveotectura pallida to determine the macroalgal seed bank along a depth gradient of habitats (surf, turf, barren and sandy zones). We collected a total of 46 limpets in two seasons (summer: August and winter: December) and from four zones at Sashiga-hama on the north-east coast of northern Honshu, Japan. The attached organisms on the limpet shells were brushed off and identified using a plastid-encoded rbcL gene and high throughput sequencing (HTS) based DNA metabarcoding. The original data set consisted of 432 macroalgal and 224 microalgal operational taxonomic units (OTUs). For macroalgae, 37, 190 and 205 OTUs were assigned to Ulvophyceae, Phaeophyceae and Rhodophyta, respectively. For canopy-forming macroalgal OTUs, Agaraceae, Alariaceae, Lessoniaceae, Laminariaceae and Sargassaceae were detected. In summer, the OTU was significantly richest in the sandy zone (77.0 ± 15.2 OTUs), but the difference among zones was less conspicuous in winter, ranging from 52.8 ± 16.4 to 64.3 ± 13.2 OTUs. The Shannon–Wiener diversity index showed similar patterns. The laminarialean and sargassacean OTUs were significantly the richest in the sandy zone during summer (p < 0.001). In light of these results, macroalgal restoration (i.e. through sea urchin removal) should be initiated in summer and the sandy zone should be preferentially targeted.

Experimental Study of Heavy Metal Dispersion through Cohesionless Soil: a Case Study of Cd+

In this case study of cadmium metal (Cd+), an experiment has been conducted on the dispersion of heavy metals through flow in porous media. Sandy soil with a specific gravity of 2.65 has been selected as a porous medium for water contaminated with Cd+. A laboratory model has been built from glass box (0.75 m length × 0.10 m width × 0.55 m height, 10 mm thickness) in order to simulate the two-dimensional flow of the polluted water. The box is divided into three zones, namely, inlet zone (upstream), outlet zone (downstream), and sandy zone. In additional, tow adjuster valves are used to control the flow from upstream to downstream direction. Furthermore, eight points are selected in order to study the effect of time/distance ratio and to obtain acceptable results through a wide range of samples. Six of these points, P1, P2, P3, P4, P5, and P6, are fixed on the side of the model, while P7 and P8 represent the sampling points on the soil surface. The experimental model is activated using continuous flow patterns with a constant average initial concentration of Cd+ (5.899 ppm). Sampling is conducted at 5, 10, 20, 30, 40, 50, and 60 min), and the filtered samples are tested using an atomic Adsorption device. The results of the laboratory test are analyzed in order to study the variations in Cd+ concentration with vertical distance (y-axis) and horizontal distance (x-axis) and to determine the effect of hydraulic gradient on Cd+ concentration. Cd+ has higher concentration at the deeper points, so sandy soil adsorbs Cd+ at higher concentrations before reaching stability. Cd+ concentrations in points closer to the upstream zone are greater than the ones in further points due to the proximity distance from the upstream zone where the concentrations represent high values. Additionally, Cd+ concentrations in P3 at the first half are greater than the ones in P5 and P6 because the adsorption process is inactive at the beginning of running the model using continuous flow.

THE DYNAMICS OF LIVELIHOOD VULNERABILITY INDEX AT FARM HOUSEHOLD LEVEL: AN EMPIRICAL ANALYSIS OF THE COASTAL SANDY ZONE IN THUA THIEN HUE PROVINCE, VIETNAM

Rural households in Vietnam have been facing various adverse impacts on their livelihoods. By using 28 indicators of Sustainable Livelihood Framework (SLF), this study aims to identify the Livelihood Vulnerability Index (LVI) of the households in the coastal sandy zone in Thua Thien Hue (TTH). Based on the baseline data in 2007-2008, the study conducted a survey of 110 households living in four districts of the region to have a thorough evaluation of LVI. The results showed that excluding the increase in natural capital index (0.194 to 0.225), the value of LVI reduced in the dimension of human capital (0.365 to 0.363), social capital (0.081 to 0.075), physical capital (0.139 to 0.048) and financial capital (0.405 to 0.273). In overall, the value of the LVI index scored 0.244 in 2007-2008 and 0.214 in 2017-2018, respectively. The research findings contribute a deeper understanding of the vulnerable context of household communities that support the issuance of policy intervention, a social project as well as impact assessment of the given factors such as change of vulnerable contexts, structure and process.

Extending the paleogeographic range and our understanding of the Neoarchean Monteville impact spherule layer (Transvaal Supergroup, South Africa)

AbstractThe Monteville spherule layer (MSL) was deposited in the Griqualand West Basin (GWB) on the Kaapvaal Craton approximately 2.63 Ga. The spherules were generated by a large impact and reworked by impact‐generated waves and/or currents. The MSL has been intersected in three previously undescribed cores. Two of the cores, GKF‐1 and GKP‐1, were drilled ~30 km west of the southernmost outcrop of the MSL. The third core, BH‐47, was drilled ~250 km south and east of the GWB. The MSL contains medium to coarse sand‐size spherules like those described previously in all three cores but each one was emplaced in a different way. In GKF‐1, the MSL is 90 cm thick and contains large rip‐up clasts of basinal carbonate and early diagenetic pyrite. In GKP‐1, the MSL is only 1.5 cm thick and consists largely of fine carbonate sand, yet it contains pyrite intraclasts up to ~1 cm long. In BH‐47, the MSL consists of a lower coarse sandy zone ~37 cm thick rich in spherules, carbonate peloids/ooids, pyrite intraclasts, and quartzose sand and an upper, finer sandy zone ~46 cm thick; neither zone contains any large intraclasts. The new occurrences triple the known extent of the MSL from ~15,000 to ~46,000 km2, support the oceanic impact model for the formation of the MSL, demonstrate that it is a persistent regional time‐stratigraphic marker, place new constraints on the Kaapvaal paleoshoreline at the time of impact, and support the existence of Vaalbara.

Genetic mechanism of the granite buried-hill reservoir of the Penglai 9-1 oilfield in Bohai Sea

The Penglai 9-1 oilfield is the largest granite buried-hill oilfield in China presently, genesis and evolution of the granite buried-hill reservoir is complex. Based on geochemical, geophysical, experimental simulation and other methods, and combined with field geological observation, genetic mechanism of the granite buried-hill reservoir of the Penglai 9-1 oilfield and its hydrocarbon accumulation mode were well investigated. Results showed that the granite was formed by magmatic intrusion along deep faults under intraplate breakup of North China Plate, it was the product of magmatic activities of Yanshan tectonic episode of Circum-Pacific Tectonic Region, and the intrusion time was 160–170 Ma of the Jurassic. Formation of the granite buried-hill reservoir was mainly controlled by the epigenic karstification and tectonic reconstruction, the Yanshanian weathering and denudation controlled macroscopic development characteristics of the granite buried-hill reservoir, and faults and joints formed by Cenozoic tectonic movement promoted modification of the granite buried-hill reservoir. Laterally, thickness of the granite buried-hill reservoir had a positive correlation with fracture density. Vertically, the granite rocks could be divided into five zones: soil zone, sandy zone, broken zone, fracture zone and base rock zone. The upper-middle part (sandy zone, broken zone, fracture zone) of the granite buried hill was the high-quality favorable reservoir zone and the main oil-bearing interval.