Northwestern Part Research Articles

Geochemistry and U-Pb zircon geochronology of the Nkout banded iron formations and associated metasiliciclastic rocks, NW Congo craton, southern Cameroon

ABSTRACT The Nkout banded iron formations (BIFs)-hosted iron deposit is located in the Ntem Complex at the northwestern part of the Congo craton, southern Cameroon. We report geochronological and geochemical data of magnetite BIFs and interlayered mica schists from the Nkout iron ore deposit. The BIFs show typical features of chemical precipitates characterized by seawater-like shale-normalized rare earth elements plus yttrium spectra. Weak positive Eu anomalies indicate the contribution of high-temperature hydrothermal fluids to the BIFs, with low detrital input. The absence of true Ce anomalies indicates that the BIFs were likely to be deposited in anoxic seawater. LA-ICP-MS U-Pb detrital zircon data for the BIFs and associated metasiliciclasltic rocks constrained the maximum depositional age at ca. 2.8 Ga, suggesting that the Nkout BIFs are likely the oldest iron formations in the Ntem Complex. Our zircon U-Pb isotope data indicate that the Nkout succession experienced lower-amphibolite facies metamorphism at ca. 2.0 Ga, which correlates with the regional tectono-thermal event linked to the convergence and assembly of terranes between the Congo and São Francisco cratons during the Eburnean-Transamazonian orogeny.

Triassic sporomorph data for the Umm Irna Formation: Age constraints from the northwestern part of Jordan

Triassic sporomorph data for the Umm Irna Formation: Age constraints from the northwestern part of Jordan

Appraisal of non-carcinogenic health risks posed by fluoride and iron in groundwater of a rural semi-arid part of India

ABSTRACT The study was initiated to evaluate groundwater quality in the post-monsoon season (2021) vis a vis chemistry and hydrochemical facies, assessment of probabilistic health risks posed by F− and Fe and quality appraisal of regional groundwater for irrigation in Kumarganj community development block. As per potable water quality standards of Bureau of Indian Standards (BIS), 50% and 13.3% of water samples were found to be unsafe due to F− and Fe, respectively. Fluoride concentration ranged from 0.1 to 3.62 mg l−1 (mean, 1.22 mg l−1). The northern, north-western and south-eastern parts of the block were found to have F− concentrations above the permissible safe limit of 1.0 mg F l−1 while a small area within southern region had >1 mg l−1 Fe. Factor analysis showed that four factors contributed to 38.21%, 19.67%, 10.62%, and 8.45%, respectively, to water quality. According to the human health risk assessment by Total Hazard Index, all age groups in the study area were at risk of exposure, in the order of THIchildren > THIinfant > THIadult due to consumption of excessive F− and Fe. This assessment was consistent with the results of probabilistic health risk assessment undertaken by Monte Carlo simulation (5000 trials) wherein maximum risk of 4.14 and 0.17 at 95th percentile to children was attributable to F− and Fe, respectively.

Hazard-mapping and health risk analysis of iron and arsenic contamination in the groundwater of Sylhet district.

This study investigates groundwater contamination by arsenic and iron and its health implications within the Sylhet district in Bangladesh. Utilizing geographic information system (GIS) and inverse distance weighting (IDW) methods, hazard maps have been developed to evaluate contamination risk across various upazilas. The findings show significant arsenic and iron pollution, particularly in the northwestern part of the district. In about 50% of the area, especially in Jaintiapur, Zakiganj, Companiganj, and Kanaighat where arsenic levels surpass 0.05 mg/L which is the standard limit of Bangladesh. Iron levels peak at 13.83 mg/L, severely impacting 45% of the region, especially in Gowainghat, northeastern Jaintiapur, Zakigonj, and Golabganj. The study employs USEPA health risk assessment methods to calculate the hazard quotient (HQ) and hazard index (HI) for both elements via oral and dermal exposure. Results indicate that children face greater noncarcinogenic and carcinogenic risks than adults, with oral HI showing significant risk in Balagonj and Bishwanath. Dermal adsorption pathways exhibit comparatively lower risks. Cancer risk assessments demonstrate high carcinogenic risks from oral arsenic intake in all areas. This comprehensive analysis highlights the urgent need for effective groundwater management and policy interventions in the Sylhet district to mitigate these health risks and ensure safe drinking water.

Adaptive Distribution and Vulnerability Assessment of Endangered Maple Species on the Tibetan Plateau

Climate change has had an almost irreversible impact on the distribution patterns of tree species on the Tibetan Plateau, driving some vulnerable species to the brink of extinction. Therefore, it is important to assess the vulnerability of tree species in climate-sensitive areas under the following three IPCC-CMIP6 scenarios: SSP126, SSP370, and SSP585. The MaxEnt model was used to predict adaptive distribution for one endangered (Acer wardii W. W. Smith (A. wardii)) and six vulnerable maple plants on the Tibetan Plateau under current and future conditions. We then evaluated their vulnerability using the landscape fragmentation index. Our results showed that the current adaptive areas of vulnerable maple species were mainly distributed in the southeast of the Tibetan Plateau. The dominant factors affecting adaptive areas were temperature annual range (BIO7) for Acer sikkimense Miq. and Acer sterculiaceum Wall.; annual precipitation (BIO12) for Acer cappadocicum Gled.; precipitation of driest month (BIO14) for Acer pectinatum Wall. ex G. Nicholson, Acer taronense Hand.-Mazz., and A. wardii; and subsoil clay fraction (S_CLAY) for Acer campbellii Hook.f. & Thoms. ex Hiern (A. campbellii) Under the three future scenarios, the adaptive areas of maple on the Tibetan Plateau area shifted to the northwest, and habitat suitability increased in the northwestern part of the adaptive areas. In the SSP370 scenario, all seven species showed an increase in adaptive areas, while certain species decreased in some periods under the SSP126 and SSP585 scenarios. The status of the endangered maple species is likely to be even more fragile under the three future scenarios. A. wardii and A. campbellii are more vulnerable and may face extinction, requiring immediate attention and protection. In contrast, the vulnerability of the remaining five species decreased. In conclusion, this study provides recommendations for conserving vulnerable maple species on the Tibetan Plateau. Our data support understanding the distributional changes and vulnerability assessment of these tree species.

Spatial Distribution Characteristics and Influencing Factors of Museums in Jining, China

In order to provide some reference suggestions for promoting the high-quality development of museums in prefecture-level cities and enhancing the regional cultural competitiveness based on an in-depth understanding of the evolutionary characteristics and the influence mechanism of spatial differentiation during the development of museums, 54 museums in Jining (China) were taken as the research object. The study analysed the spatial distribution characteristics of museums in each county and district of Jining and the main influencing factors were explored. The results showed that: (1) museums in Jining tend to be cohesively distributed, mainly concentrated in the central to the northern part of Jining, followed by the north-western part, with a minor distribution in the eastern and southern parts, and the distribution of museums was uneven within Jining; (2) in terms of spatial distribution, museums in Jining have formed a major aggregation area of Qufu-Yanzhou-Rencheng, as well as a sub-aggregation area, centred on Liangshan, and Weishan, Yutai, and other places in southern Jining, although there were museums distributed, compared to the overall distribution, they were fewer in number, smaller in scope, and less evident in aggregation. (3) In terms of influencing factors, the distribution pattern of museums in Jining was related to resource endowment, highway accessibility, and water distribution, i.e., the distribution of museums was more frequent in areas with more natural and historical resources, a developed highway network, and areas near rivers or lakes. The socio-economic situation, the degree of tourism development, and the degree of population density also affected the layout of museums to a certain extent.

Independent contributions of tropical sea surface temperature modes to the interannual variability of western North Pacific tropical cyclone frequency

AbstractThis study investigates the independent contributions of three tropical sea surface temperature anomaly (SSTA) modes to interannual changes in summertime western North Pacific (WNP) tropical cyclone (TC) frequency from 1982 to 2022. We primarily analyse partial regressions of TC metrics and environmental variables onto the El Niño–Southern Oscillation Modoki (ENM), North Indian Ocean (NIO) SSTA and tropical North Atlantic (TNA) SSTA indices. We find that although basinwide WNP TC frequency significantly correlates with both the ENM and NIO indices, the regions with the most significant changes in TC formation induced by these two indices are well separated. During El Niño Modoki, significant increases in TC formation concentrate over the southeastern part of the WNP, while during a warm NIO, significant decreases in TC formation concentrate over the northwestern part of the WNP. By contrast, insignificant changes in TC genesis over the WNP are solely induced by TNA SSTAs. We show that the two pathways of TNA SSTA's influence on WNP TC activity through modulation of Pacific and NIO SSTAs are of comparable importance. During El Niño Modoki, significantly enhanced TC genesis over the southeastern WNP can be explained by more favourable environmental conditions, which is linked to an anomalous low‐level cyclonic circulation over the WNP. During a warm NIO, TC genesis is significantly suppressed over the northwestern WNP, due primarily to an anomalous low‐level anticyclonic circulation‐induced decrease in relative vorticity. By contrast, during a warm TNA, no notable changes in environmental variables are found over most of the WNP, while significant flow anomalies are limited to the central‐to‐eastern Pacific and the western Atlantic. These results highlight that the TNA SSTA by itself has a limited impact on WNP TC genesis and the associated large‐scale environment.

Spatio-Temporal Variation of Cyanobacteria Blooms in Taihu Lake Using Multiple Remote Sensing Indices and Machine Learning

In view of the ecological threat posed by cyanobacteria blooms in Taihu Lake (China), this paper presents a study on the area of cyanobacteria extent based on MODIS data using the quantum particle swarm optimization–random forest (QPSO-RF) machine learning algorithm. This paper selects multiple remote sensing input indices that can represent the characteristics of the primary underlying type in Taihu Lake. The proposed method performs best, with an F1 score of 0.91–0.98. Based on this method, the spatio-temporal variation of cyanobacteria blooms in the Taihu Lake complex was analyzed. During 2010–2022, the average area of cyanobacteria blooms in Taihu Lake increased slightly. Severe-scale cyanobacteria blooms occurred in 2015–2019. Cyanobacteria blooms were normally concentrated from May to November. However, the most prolonged extended duration occurred in 2017, lasting for eight months. Spatially, cyanobacteria blooms were mainly identified in the northwestern part of Taihu Lake, with an average occurrence frequency of about 10.0%. The cyanobacteria blooms often began to grow in the northwestern part of the lake and then spread to the Center of the Lake, and also dissipated earliest in the northwestern part of the lake. Our study is also beneficial for monitoring the growth of cyanobacteria blooms in other similar large lakes in long time series.

Electrical Resistivity Techniques for Groundwater Studies in North-Western Part of District Hisar, Haryana, India

Abstract Haryana is one of the dominant agrarian states of India but salinity in the groundwater is one of the major concerns in the state. The salinity in groundwater is observed from top itself in the central part of Haryana consisting of Hisar, Jind, Rohtak, and Jhajjar districts. As a result, local inhabitants are facing severe problems with the nonavailability of fresh drinking water. In some places, shallow aquifers are having marginally saline water which is used by the local inhabitants in dry months. Groundwater even in shallow aquifers also becomes saline due to less rainfall and intrusion of saline water from lower layers. In some areas, the thickness of freshwater columns has been reduced significantly due to the excessive withdrawal of fresh water and intrusion from underlying saline groundwater aquifers. It is therefore pertinent to study fresh/saline groundwater interface to solve these problems on scientific basis. The geophysical methods especially electrical resistivity method has proved very useful for the estimation of fresh/ saline groundwater interface. The present paper deals with the findings of electrical resistivity survey conducted in Adampur and Agroha blocks of district Hisar, Haryana, India. Thirty-five Vertical Electrical Soundings (VES) were conducted in these areas for this purpose. The results indicate that the entire study area is occupied with marginally saline to highly saline groundwater. The study shows the presence of a thin layer of marginally saline groundwater almost uniformly distributed in the entire study area.

Dissection of figured wood trait in curly birch (Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti) using high-throughput genotyping

Curly (Karelian) birch is a special variety of Betula pendula Roth distributed in the northwestern part of Europe. Karelian birch is well-known for its valuable figured curly wood also known as “wooden marble”. The genetic basis underlying curly wood formation has been debated since last century, however, there was no data about loci responsible for the curly wood trait. In the present study, we analyzed two full-sibs populations derived from experimental crosses of curly birches and segregating for the trait. RADseq genotyping was applied to reveal how many loci are involved in ‘curliness’ formation and to search for genetic variants associated with this trait. One single interval on chromosome 10 was detected containing possible candidate genes. InDel marker BpCW1 was suggested for the first time for marker-assisted selection of trees with curly wood at their earliest stages of development.

A contribution to the understanding of the origin of the Ginebra Gold District mineralizations, Colombia

Ginebra´s gold mineralization is hosted by the Ginebra Ophiolitic Massif and the Buga Batholith, in the western flank of the Central Cordillera of Colombia. Gold occurs as disseminations, quartz-carbonate stockwork veinlets and quartz lodes with a strong structural control and are composed by small amounts of sulfides, mostly pyrite, with galena, sphalerite and chalcopyrite in at least two different deposition events and related to strong sericite-chlorite-epidote haloes, indicative of near-neutral and reduced fluids. Petrography and Raman spectroscopy allowed to identify two main fluid inclusions assemblages primary to pseudo-secondary in origin, both of them aqueous and CO2-rich, with variable N2. Microthermometric analysis indicates the hydrothermal fluids associated with the gold were low saline (0.75-6.22 wt% NaCl equiv.) and presented a minimum trapping temperature ranging from 237.4 to 301.6°C. Petrography and microthermometric results suggest an isothermal fluid mixing and/or H2S loss as the main mechanisms related to gold bi-sulfide/thio-sulfide complexes destabilization and precipitation. Sulfur isotopes indicates a close to zero range (-8.2-+4.8‰), suggesting a restricted fluid circulation through the magmatic rocks of the Buga Batholith and the Ginebra Ophiolitic Massif. Besides, the oxygen and deuterium isotopes from hydrothermal sericite and chlorite accompanying to gold events, indicates a metamorphic origin for the hydrothermal fluids. 40Ar-39Ar dating of the hydrothermal alteration haloes, from El Retiro and La Esperanza, indicates a late Cretaceous-Paleocene age, between 67 and 65 Ma, contemporaneous with a regional strong dextral transpressive deformation related to subduction to obduction and exotic terrane accretion against the north-western part of the South American Plate. Although the hydrothermal fluid characteristics of the Ginebra Gold Disctrict are compatible with both the Intrusion-Related and Orogenic Gold deposit types, the metamorphic nature of the hydrothermal fluids and the tectonic regime at the time of mineralization event, allow us to propose they are compatible with an Orogenic Gold deposit.

Evaluation of fish pituitary spheroids to study annual endocrine reproductive control

The pituitary gland is a small endocrine gland located below the hypothalamus. This gland releases several important hormones and controls the function of many other endocrine system glands to release hormones. Fish pituitary hormonal cells are controlled by neuroendocrine and sex steroid feedback. To study the complex pituitary function in vivo, we established an in vitro pituitary spheroid assay and evaluated its suitability for monitoring the annual reproductive physiological conditions in Takifugu rubripes, also known as torafugu, is one of the most economically important species distributed in the northwestern part of the Pacific Ocean, in the western part of the East China Sea, and in more northern areas near Hokkaido, Japan. Fish pituitary spheroids can be easily constructed in liquid or solid plates. The culture medium (L-15) made the aggregation faster than MEM (Hank’s). A Rho-kinase inhibitor (Y-27632, 10 μM) and/or fish serum (2.5 %) also promoted spheroid formation. Laser confocal microscopy analysis of spheroids cultured with annual serum of both sexes revealed that luteinizing hormone (LH) synthesis has the highest peak in the final maturation stage (3 years old, May) in accordance with the highest serum sex steroid levels; in contrast, follicle stimulating hormone (FSH) synthesis has no correlation with the dose of serum or nutrients. Similarly, 3D cell propagation assays using female serum showed that total pituitary cells displayed the highest proliferation at puberty onset (2 years old, October) before half a year of the spawning season. These results indicate that pituitary spheroids are useful in vitro models for monitoring the reproductive physiological status of fish in vivo and may be applicable to the in vitro screening of environmental chemicals and bioactive compounds affecting reproductive efficiency in aquaculture.

Soil erodibility mapping of hilly watershed using analytical hierarchy process and geographical information system: A case of Chittagong hill tract, Bangladesh

Soil erosion across watersheds and river basins is an alarming environmental deterioration process that poses severe risks to hydrological systems, hydrogeochemical processes, agricultural productivity, and the global natural ecosystem. The use of the Analytical Hierarchy Process (AHP) and Geographical Information System (GIS) to assess soil erosivity for the watershed is widely known. This study applied the AHP and GIS to understand the degree of erosivity of the hilly Karnaphuli watershed in Chattogram, Bangladesh. The study used topographical maps, soil maps, and satellite imagery datasets. It implemented the GIS-based AHP and weighted overlay technique to derive eight factors (slope, elevation, Stream Power Index (SPI), Land Use and Land Cover (LULC), curvature, soil, Topographic Wetness Index (TWI), and rainfall. The geological stage of erosion potential was also identified using Digital Elevation Model (DEM) data through GIS-based hypsometric analysis. The findings demonstrated that the eastern and north-western parts are particularly vulnerable to erosion compared to other parts of the study area. The most dominant variables identified to influence the process of soil erosion are slope, LULC, elevation, and SPI. According to the AHP analysis, slope was the most influential factor (26%), followed by LULC (23.8%), elevation (20.3%), and SPI (13.9%) in the soil erosion process, and the geological stage of erosion potential was determined from the hypsometric curve (S-shaped) and hypsometric integral (0.49), which revealed that moderately eroded areas characterized the whole research region. The findings are significant as they provide valuable information for researchers and planners to address soil erosion and develop measures to control it effectively.

Growth charts for weight and height of Indian children with Down syndrome.

Age and gender specific growth charts for Indian children with Down syndrome (DS) based on longitudinal data have not been published. To establish percentile growth charts for DS children inhabiting northwestern parts of India, body weight and length/height of 1125 (Male: 752, Female: 373) children with DS aged <1 month to 10 years, enrolled from the "Genetics Clinic" were measured at half yearly age intervals in the "Growth Clinic" of the Institute from August 1994 to November 2018. A total of 2089 observations were made on these children using standardized anthropometric techniques and instruments following a prospective mixed-longitudinal growth research design. Using the LMS method, age and sex-specific percentile growth charts (<1 month to 10 years) for weight, and length/ height were generated. Unpaired t-test was used to compare mean growth attainments of study children with those of DS patients representing other population groups as well as their normal Multicentre Growth Reference Study (MGRS and Indian Academy of Pediatrics (IAP) counterparts. The 50th percentile growth curves for both weight and length/height of Indian children with DS demonstrated a regular increase. As compared to their normal MGRS and Indian (IAP) counterparts, the children with DS had lower weight and height attainments. The boys and girls with Down syndrome showed short stature (height < 3rd centile) from the age of 1 year till 10 years and also became underweight beyond 5 years. As compared to their normal counterparts, children with Down syndrome exhibited compromised auxological attainments. The use of growth charts presented herein may be used to compare and monitor growth and nutritional status of Indian children with Down syndrome.

Age and fluid source constraints of the Haoyaoerhudong orogenic gold deposit, North China: Evidence from geochronology and noble gas isotopes

The Haoyaoerhudong gold deposit, located in the northwestern part of the North China craton (NCC), has produced over 120 metric tonnes (t) of gold since 2007. It has a total reserve of > 240 t at average gold grade of 0.62 g/t, making it one of the largest open pit gold mines in China. The steeply dipping, large-tonnage, low-grade, vein- or veinlet-type gold orebodies are hosted in strongly-deformed Mesoproterozoic carbonaceous schist of the Bayan Obo Group. The laminated/boudinaged veins/veinlets in the sinistral ductile–brittle shear zones are dominated by quartz, biotite, gold-bearing löllingite, pyrrhotite, (arseno)pyrite, with minor native gold, titanite and xenotime. In this paper, we present new in situ U–Pb geochronological data on magmatic zircon from the pre-ore dikes, on metamorphic and hydrothermal xenotime, and on hydrothermal titanite from the hydrothermally altered carbonaceous schist and auriferous quartz–sulfides veins/veinlets, as well as He-Ar isotopic analysis on gold-bearing (arseno)pyrite in the syn-ore stage. The metamorphic xenotime U–Pb age of 426 ± 6.0 Ma (2σ) records a regional metamorphic event, possibly related to the accretion of the Bainaimiao arc onto the NCC. Two pre-ore andesitic dikes yielded similar emplacement ages at ∼ 278 Ma constrained by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U–Pb zircon data. Hydrothermal xenotime grains from the altered carbonaceous schist and auriferous quartz–sulfides veins yielded U–Pb ages of 256.0 ± 4.1 Ma (2σ) and 254.4 ± 2.1 Ma (2σ), respectively, overlapping with that of the hydrothermal titanite at 255.4 ± 0.8 Ma (2σ) from the laminated quartz–sulfides veinlets. This indicates that the gold mineralization occurred at ca. 255 Ma. The ∼ 255 Ma gold mineralization age is much younger than the previously reported Early–Middle Permian regional magmatic activity (ca. 291 Ma to 268 Ma), and may be associated with the regional sinistral strike-slip event in the late orogenic cycle related to the collision between the Siberian craton and the NCC. The 3He/4He (R/Ra) and 40Ar/36Ar values of the gold-bearing (arseno)pyrite are 0.04 to 0.09 (average = 0.07) and 375.8 to 2023 (average = 1045), which reveal the ore-forming fluids dominantly originated from the crustal rocks, with limited involvement from the mantle. Collectively, our new geochronological data, noble gas isotopic analyses, and geological evidence support a typical orogenic gold deposit model at Haoyaoerhudong.

&lt;div&gt;First record of saproxylic beetle Corticeus (= Hypophloeus) unicolor Piller &amp;amp; Mitterpacher, 1783 in Montenegro (Coleoptera: Tenebrionidae) with comments on old-growth forests conservation in the Country&lt;/div&gt;

The occurrence of Darkling Beetle Corticeus (=Hypophloeus) unicolor Piller &amp; Mitterpacher, 1783 (Coleoptera: Tenebrionidae), a saproxylic predator beetles, is reported for Montenegro. The species develops in freshly the dead wood of birch, beech, and oak trees. It is probably a predator of the larvae of the beetle Hylecoetus and other wood borers. C. unicolor was found in the Biogradska Gora National Park, in the north-western part of the Bjelasica mountain range in the Dinaric Alps (Montenegro), in October 2022 in an old-growth beech forest at about 1,000 m elevation.

Unlocking the sustainable value with digitalization: Views of maritime stakeholders on business opportunities

Digitalization in the maritime sector encompasses interconnected technologies that enhance efficiency, risk mitigation, and safety in marine operations and offshore assets management. Digital twin, or virtual assets, plays a pivotal role within this digital ecosystem. This study aims to explore the transformative potential of digital twins in the maritime industry, focusing on their capacity to improve sustainability, optimize productivity, and drive innovative business models. A quantitative methodology was employed to investigate this potential in the maritime sector, utilizing questionnaires to gather insights and perspectives from key stakeholders in the Northwestern part of Norway’s maritime industry, including ship designers, shipyards, equipment suppliers, and ship owners. Among the 23 respondents, there were individuals holding senior, leadership, management, and specialized digitalization roles. Notably, 65% of these respondents possessed over 20 years of experience in the maritime industry. The survey reveals a strong interest in adopting digital twins within the maritime sector (70% of respondents). The findings underscore the potential advantages of digital twin solutions, including predictive maintenance (16%), real-time operational efficiency enhancements (17%), and design optimization (18%). Nevertheless, implementation complexity (73.9%) and data integration (73.9%) loom significant obstacles. Respondents also recognize the potential for new product opportunities and innovative business models arising from digital twin implementation. Sustainability initiatives are emphasized, particularly in real-time monitoring (83%), retrofitting (74%), and predictive maintenance (65%). Cybersecurity (65%) and data protection (62%) are critical concerns. Furthermore, implementing digital twins is anticipated to promote collaboration and information sharing among maritime industry stakeholders, underscoring their potential for transformative impact.

Hepatitis E outbreak in the health district of Bocaranga-Koui, Central African Republic, 2018–2019

BackgroundHepatitis E virus (HEV) is a major public health disease causing large outbreaks and sporadic cases of acute hepatitis. We investigated an outbreak of HEV infection that occurred in September 2018 in the health district (HD) of Bocaranga-Koui, located in the northwestern part of Central African Republic (CAR).MethodsBlood samples were collected from 352 patients aged 0–85 years suspected to be infected with yellow fever (YF), according to the World Health Organization YF case definition. The notification forms from recorded cases were used. Water consumed in the HD were also collected. Human samples found negative for anti-YF IgM were then tested by ELISA for anti-HEV IgM and IgG antibodies. Positive anti-HEV (IgM and/or IgG) samples and collected water were then subjected to molecular biology tests using a real time RT-PCR assay, followed by a nested RT-PCR assay for sequencing and phylogenetic analysis.ResultsOf the 352 icterus patients included, anti-HEV IgM was found in 142 people (40.3%) and anti-HEV IgG in 175 (49.7%). Although HEV infection was detected in all age groups, there was a significant difference between the 0–10 age groups and others age groups (P = 0.001). Elevated levels of serum aminotransferase were observed in anti-HEV IgM-positive subjects. Phylogenetic analysis showed HEV genotype 1e in infected patients as well as in the contaminated water.ConclusionThis epidemic showed that CAR remains an HEV-endemic area. The genotype 1e strain was responsible for the HEV outbreak in Bocaranga-Koui HD. It is necessary to implement basic conditions of hygiene and sanitation to prevent further outbreaks of a HEV epidemics, to facilitate access to clean drinking water for the population, to launch intensive health education for basic hygiene measures, to sett up targeted hygiene promotion activities and, finally, to ensure that formal health care is available.

Northwestward migration of siliciclastic sedimentation during late Tonian to Cambrian: Implications for tectonic evolution of the South China Block

The late Tonian to Cambrian sedimentary sequences in the Xiang-Gui-Yue (XGY) Basin across the potential suture zone between the Yangtze and Cathaysia blocks preserves invaluable information on the geological evolution of the South China Block, while the sedimentary provenance is not well constrained and tectonic affinity of the basin is still highly controversial. This study presents systematic provenance analysis of late Tonian to Cambrian clastic rocks to reconstruct the formation and evolution of sedimentary basin. A significant change from dominant 900–700 Ma to dominant 1300–900 Ma zircons in sediments has been observed along with the basin evolution. It has been widely considered that the 900–700 Ma detritus are largely from the Yangtze Block in the northwest, while the 1300–900 Ma detritus are from the Cathaysia Block in the southeast or terranes linked to the Cathyasia Block at that time. More remarkably, the provenance transition occurred at Cryogenian, Ediacaran and Cambrian in the southeastern, central and northwestern parts of the XGY Basin, respectively. All the above observation indicates the Yangtze-derived detritus arrived at the southeast end of the basin as early as late Tonian and gradually faded away until at least Ordovician, as probably caused by the denudation of the Jiangnan Orogenic Belt after the amalgamation of the Yangtze and Cathaysia blocks. On the other hand, the Cathaysia-derived detritus became dominant due to the uplift of the Cathaysia Block. The XGY Basin was a rift basin until ca. 660 Ma, evolved into a passive margin setting during Ediacaran-early Cambrian, and became a foreland basin after the middie-late Cambrian. Collectively, the provenance variation from late Tonian to Cambrian basin suggests that the Yangtze and Cathaysia blocks may have been amalgamated before late Tonian and an intra-plate basin has been developed along the orogenic belt, allowing the formation and evolution of the XGY Basin.

Zoning strategies for ecological restoration in the karst region of Guangdong province, China: a perspective from the “social-ecological system”

Ecological restoration holds great significance in addressing environmental degradation and rock desertification in karst areas. Zoning strategy is a fundamental task in understanding the interrelationship between human-environment to foster sustainable development. We explore “social-ecological” system and conduct a case study on the karst region in Guangdong Province, China. An evaluation framework consists of “development pressure”, “sensitivity status”, and “resilience potential” was established. The results show that: regions with high pressure of development are predominantly located in high-density urban areas. The generally distribution of the comprehensive status index exhibits significant spatial heterogeneity. Regions with low sensitivity are found on the eastern and western sides of the study area. The comprehensive resilience values are largely influenced by per capita energy-saving and environmental protection expenditures. The restoration zones mainly concentrated in the contiguous regions of the northwestern and southern parts, covering more than half of the total area. The conservation zones are more numerous and primarily situated in the northern and eastern parts. By integrating socio-economic and ecological factors, this study proposes ecological restoration strategies for specific zones. It helps for improve development issues arising from complex interactions between human-environment, facilitating the implementation of restoration practices.