Khon Island Research Articles

Detection of Schistosoma mekongi DNA in Human Stool and Intermediate Host Snail Neotricula aperta via Loop-Mediated Isothermal Amplification Assay in Lao PDR.

Schistosomiasis mekongi infection represents a public health concern in Laos and Cambodia. While both countries have made significant progress in disease control over the past few decades, eradication has not yet been achieved. Recently, several studies reported the application of loop-mediated isothermal amplification (LAMP) for detecting Schistosoma DNA in low-transmission settings. The objective of this study was to develop a LAMP assay for Schistosoma mekongi using a simple DNA extraction method. In particular, we evaluated the utility of the LAMP assay for detecting S. mekongi DNA in human stool and snail samples in endemic areas in Laos. We then used the LAMP assay results to develop a risk map for monitoring schistosomiasis mekongi and preventing epidemics. A total of 272 stool samples were collected from villagers on Khon Island in the southern part of Laos in 2016. DNA for LAMP assays was extracted via the hot-alkaline method. Following the Kato-Katz method, we determined that 0.4% (1/272) of the stool samples were positive for S. mekongi eggs, as opposed to 2.9% (8/272) for S. mekongi DNA based on the LAMP assays. Snail samples (n = 11,762) were annually collected along the riverside of Khon Island from 2016 to 2018. DNA was extracted from pooled snails as per the hot-alkaline method. The LAMP assay indicated that the prevalence of S. mekongi in snails was 0.26% in 2016, 0.08% in 2017, and less than 0.03% in 2018. Based on the LAMP assay results, a risk map for schistosomiasis with kernel density estimation was created, and the distribution of positive individuals and snails was consistent. In a subsequent survey of residents, schistosomiasis prevalence among villagers with latrines at home was lower than that among villagers without latrines. This is the first study to develop and evaluate a LAMP assay for S. mekongi detection in stools and snails. Our findings indicate that the LAMP assay is an effective method for monitoring pathogen prevalence and creating risk maps for schistosomiasis.

Spatial and temporal differences in Late Neolithic Serovo to Early Bronze Age Glazkovo forager diet in Lake Baikal's Little Sea Microregion, Siberia

Research on Middle Holocene hunter-gatherers from the Cis-Baikal region of Eastern Siberia has yielded many insights into their dietary and mobility patterns. A large dataset of stable carbon (δ13C) and nitrogen (δ15N) isotope values, when paired with freshwater-reservoir corrected carbon-14 dates, allows us to conduct fine-scale investigations into dietary change. Our Small Cemeteries Project has increased the sample of Late Neolithic (LN) Serovo individuals, and Ol'khon Island burials, allowing for new investigations into changes between the Serovo and subsequent Early Bronze Age (EBA) Glazkovo mortuary traditions in the Little Sea Microregion. This is important because research exploring the extent and nature of cultural continuity and change between these mortuary traditions has received less attention than more pronounced earlier transitions. We use stable isotope data from 134 adolescents and adults to explore (1) temporal changes in δ13C and δ15N values across the Serovo and Glazkovo mortuary traditions, and (2) differences in stable isotope values between individuals buried on Ol'khon Island vs. the Mainland. During Serovo times, Islanders and Mainlanders were eating somewhat different diets, with the former consuming more seal and the latter more shallow-water fish. Glazkovo Islanders maintained a broadly similar diet to their Serovo Islander predecessors suggesting the continued existence of a specialized group of Island seal hunters. After ~4100 calBP, and the arrival of the Glazkovo mortuary tradition in the Little Sea Microregion, there is the appearance of a new group of Mainlanders consuming a diet with low δ15N (≤ 14.6‰) and/or low δ13C (≤ ˗19.0‰) values unlike anything seen previously. This diet included less lake fish and seal and more terrestrial herbivores. Previous research has shown that many Mainland Glazkovo individuals with this new diet were non-local. Our study finds that just over half of Glazkovo Mainlanders have a low δ13C or δ15N value and they are found in all cemeteries with multiple individuals. This suggests such individuals, many of which were non-local, were fully incorporated into local social groups. Further increasing the sample of LN and Island individuals is needed to better establish these findings; nonetheless, our research highlights the diversity in Middle Holocene adaptive strategies in the Little Sea Microregion.

Origin of Skarns at Migmatization on Ol’khon Island, Lake Baikal, Russia

Migmatites on the western shore of Ol’khon Island host unusual rocks: zoned lenses of hedenbergite–garnet–epidote–anorthite metasomatites coupled with the migmatites. No intrusive granites were found nearby. The skarn-forming process operated at the interface of the granite gneiss and skarn protolith (perhaps, carbonate rocks). The composition of the metasomatites is analogous to that of calcic skarns with high Al2O3, FeO, and CaO concentrations. The compositions and relations of the minerals provide evidence of the successive development of the hedenbergite–anorthite outer zone, dominantly anorthite–garnet main zone, and quartz-enriched inner zone, with all of the zones parallel to contact with the granite gneiss. The granite gneiss itself is also likely of metasomatic nature, as follows from its supraeutectic concentration of potassic feldspar in the leucosome and low crystallization temperatures. A minimum of the Gibbs free energy (calculated with the SELECTOR-C program package) was reached at 8 kbar and temperatures of 600– 625°C. These parameters are lower than the melting temperature of the granite eutectic, and the absence of melt is confirmed by the absence of melt inclusions in minerals of the granite gneisses. This indicate that the driving force of the process was migmatizing silicic–potassic solutions. The P–T parameters of the skarns are close to the foregoing values. The very high Sr and Ca and low Mg concentrations suggest that the protolith of the skarns was calcite marble. The enrichment of the skarns in the granitophile elements suggests that the skarns were produced simultaneously with and in genetic relation to the migmatization processes. The metasomatites were formed before the partial melts were derived, early in the course of the granite-forming processes and provide important information for better understanding the metasomatic process responsible for the exchange of chemical elements between the rocks.

Origin of Skarns at Migmatization on Ol’khon Island, Lake Baikal, Russia

Origin of Skarns at Migmatization on Ol’khon Island, Lake Baikal, Russia

Sources and Provenances of Late Cenozoic Sand Deposits of the Ol’khon Island (Baikal Rift Zone)

Geochronological (LA–ICP–MS) U–Th–Pb studies of detrital zircon of the Late Cenozoic sand deposits on Ol’khon Island have been performed. It has been shown that their main source is represented by Early Paleozoic igneous and metamorphic complexes of the Ol’khon Terrane of the Central-Asian Mobile belt and Late Carboniferous–Early Permian granitoids of the Angara–Vitim batholite. Sands from the source were transported over a distance of no less than 100 km. It is supposed that it was effectuated by strong air flows, over the ice on the Lake Baikal in particular.

Ferromanganese nodules of freshwater reservoirs of Ol’khon Island (Baikal) and the Kulunda Plain (West Siberia)

Morphology and mineralogical and geochemical compositions of freshwater ferromanganese nodules of Ol’khon Island (Sasa Formation) and Kulunda Plain (Lake Porozhnee) were studied. The study has shown rhythmic structures of the nodules, formed by macro- and microlayers with mineralized microflora. The layers are composed of either crystalline Mn mineral phases and finely dispersed Fe phases (Lake Porozhnee) or, on the contrary, crystalline goethite and X-ray amorphous Mn phases (Ol’khon Island). Separation of Mn and Fe mineral phases in the nodules proceeded during their formation and diagenesis. The freshwater nodules show both high (Lake Porozhnee) and low (Ol’khon Island) Mn/Fe ratios. The predominance of Fe phase in the Ol’khon nodules accounts for their high contents of REE, including Ce. The Porozhnee nodules grew, most likely, more rapidly, which is reflected in their low REE contents and Ce anomaly. The examined chemical and mineral compositions, textures, and structures of the nodules testify to the low-temperature hydrothermal source of their ore substance.

Geochemistry of alkali syenites from the Budun massif and their petrogenetic properties (Ol’khon Island)

The first data on the geochemistry of the alkali syenite massif in Cape Budun of Ol’khon Island, where it makes contact in the south with the Khuzir gabbroid massif, are presented. Syenites occur among granite gneisses of the Sharanur dome and, like its granites, are enriched with Zr and REEs, but depleted in other trace elements. They contain anorthoclase, corundum, rare nepheline, zircon, and hercynite and are accompanied by desilicified pegmatites. Their unusual geochemical properties allow the assumption that alkaline magmas resulted from the interaction between basic and granitoid melts.

Paleozoic collisional and intraplate granitoids of the Baikal area: comparative geochemistry and petrogenesis

Early Paleozoic granitoids of autochthonous and allochthonous facies in the Baikal area (Ol’khon Island, Khamar-Daban Ridge) are in close spatial association with gneisses, migmatites, and plagiogranites and are usually confined to granite–gneiss domes. They are virtually not subjected to magmatic differentiation. Formation of granitoids of the Solzan massif and Sharanur complex lasted 26–28 Myr, which might be considered an indicator of collisional granitoid magmatism. Collisional granitoids of different provinces have a series of indicative features: They are peraluminous and highly potassic and are enriched in crustal elements (Rb, Pb, and Th) but sometimes have low contents of volatiles. In contrast to collisional magmatism, petrogenesis of intraplate granitoids does not depend on the composition and age of the enclosing rocks. The geochemical evolution of intraplate granitoid magmatism in the Baikal area is expressed as an increase in contents of F, Li, Rb, Cs, Sn, Be, Ta, Zr, and Pb and a decrease in contents of Ba, Sr, Zn, Th, and U during the differentiation of multiphase intrusions. The geochemical diversity of these granitoids formed both from crustal and from mantle sources and as a result of the mantle–crust interaction, might be due to the effect of plume on the geologic evolution of intraplate magmatism. The wide range of compositions and geochemical types of igneous rocks (from alkali and subalkalic to rare-metal granitoids) within the Late Paleozoic Baikal magmatism area suggests its high ore potential.

Conditions and formation mechanism of carbon phases in late quarternary geyzerites and travertines of Ol’khon area and Ol’khon Island (Baikal rift zone)

Late Quaternary geyserite and travertine in Ol’khon Area and Ol’khon Island contain a recently discovered high-temperature association of hydrocarbon and carbonaceous phases, including highly crystalline graphite, α-carbyne, and bitumen, which were produced at temperatures no lower than 400°C. A carbon modification α-carbyne, which was previously found only among experimental products, was first identified in geyserite from the Ol’khon area. Nanometer-sized morphostructures and crystallites were detected on the surface of highly crystalline graphite from the geyserite and travertine. No such structures and crystallites have ever been found on graphite of magmatic, metamorphic, metasomatic, or pneumatolytic origin. The newly formed nanometer-sized morphostructures and crystallites should be regarded as typomorphic features of carbonaceous phases in high-temperature hydrothermal rocks. Graphite was likely produced in the geyserite and travertine by low-pressure polycondenssation of hydrocarbons, at free growth in open space from oversaturated solutions and/or a gas phase.

Thymus baicalensis (Lamiaceae) morphological transformation under different environmental conditions

Thymus baicalensis shoot formation and life-form diversity have been studied under the different environmental conditions of Ol’khon Island. It has been determined that a species life form represents a vegetative immovable aerial–axial dwarf shrub under mountain-steppe–hilltop conditions, while on the hill slope it is a vegetative immovable dwarf shrub of an elfin–wood–formation type; it tends to be cushionshaped in sandy steppes. The basis of a mature specimen can be formed by a monopodial and sympodial main axis increasing in increments. Changes in skeletal axis structures, length of time for their increase in increments, species-specific rooting characteristics, and spatial configuration can be the mechanisms of morphological adaptation to different ecological and coenotic conditions.

Performing “culture” : diverse audiences at the International Shaman’s Conference and Tailgan on Ol’khon Island

Cet article examine la session annuelle de la Conférence Chamanique Internationale et du Tailgan sur l’île d’Ol’hon, dans le lac Baïkal, sous l’angle de la prestation “culturelle” qu’elle présentait. Il en découle une question de méthode : les données relatives aux participants aident-elles à comprendre la cérémonie ? L’enquête démographique montre la grande diversité du public ; du fait de la variété des raisons d’assister et des attentes, les impressions retirées de cette session sont très différentes. La cérémonie elle-même reflète cette diversité, que les discours d’ouverture ont pragmatiquement tenté d’encadrer en parlant de “culture locale à valeur globale”. Du fait que “local” et “culture” restent non définis, les Bouriates locaux et les membres de l’association Tengeri peuvent percevoir cette “culture locale” comme une contribution à la revitalisation des pratiques chamaniques bouriates, tout en permettant aux pèlerins New Age de trouver quelque chose d’universel sous une forme bouriate locale.

Characteristics of PAHs, PCDD/Fs, PCBs and PBDEs in the Sediment of Lake Baikal, Russia

The levels of PAHs, PCDD/Fs, PCBs, and PBDEs in Lake Baikal were monitored for the first time using deep water sediment. The sediment samples were collected from 15 stations in four regions of Lake Baikal: Ol’khon Island (n = 8), the Angara River estuary (n = 2), the Selenga River delta (n = 2), and the Baikal pulp and paper mill (BPPM) (n = 3). The highest average concentrations of PCDD/Fs (20.24 pg/g d.w.) and PCBs (68.72 ng/g d.w.) were found at Ol’khon Island. The highest total PBDE concentrations were found at BPPM, with a mean concentration of 575.76 pg/g d.w. For PCBs, PCB-52, and PCB-69 were dominant, making up 11% of the total 209 PCB congeners. BDE-209 contributed 60% of PBDEs in Lake Baikal. According to the TPEQ concentration of PAHs, PAHs contributed the most to Lake Baikal contamination. The sources of contamination of PAHs, PCDDs, and PCBs in Lake Baikal are identified as combustion, runoff from the use of the pesticides (PCP) and insulating oil, specifically for PCBs. The source of PBDEs is assumed to be production, use and disposal of products containing PBDEs, in addition to atmospheric long-range transport and deposition.

Composition and geochemical typization of granitoids from Ol’khon Island (Sharanurskii Complex)

Composition and geochemical typization of granitoids from Ol’khon Island (Sharanurskii Complex)

U-Pb isotopic dating of zircons (SHRIMP-II) from granulites of the Ol’khon region of Western Baikal area

Based on the first isotopic geochronological data obtained by the classic U–Pb method by zircons [1–3], it was established that magmatic and metamorphic rocks of the Ol’khon region are of Early Paleozoic age. The age of granulite metamorphism of the Chernor� udskaya zone rocks spreading as a narrow band (with a width of <1 km) along the boundary of the Siberian Craton was 485 ± 5 Ma. Data of the SHRIMP ion microprobe for U–Pb isotopic dating of zircons [4, 5] confirmed previously obtained results: age estimations were 507 ± 8 Ma, for granulites in the northeastern part of the Chernorudskaya zone (Khadarta Penin� sula) and 498 ± 7 Ma, for the Khoboi Cape (Ol’khon Island). However, problems concerning age estima� tions for the protolith of these rocks remained unsolved. Our study is aimed at solution of these prob� lems.

A new Miocene fauna of snakes from eastern Siberia, Russia.: Was the snake fauna largely homogenous in Eurasia during the Miocene?

Togay, a locality from Ol’khon Island, Baykal Lake, Russia, has yielded a fauna of snakes of Late Middle or early Late Miocene age. It is located in a broad area from which no Neogene snake has been reported; therefore, it represents an important landmark. The fauna includes a non-erycine boid, two or three colubrids, a viperid of the ‘oriental complex’ of Vipera, and perhaps another viperid. This assemblage is astonishingly reminiscent of the snake faunas from the late Early and early Middle Miocene from western and central Europe, it being understood that Miocene faunas are practically unknown in the geographically intermediary area. It may be entertained whether a homogenous snake fauna inhabited Eurasia (except the southern part of the continent) during the Miocene.

Composition, P-T parameters, and metasomatic transformations of mafic schists of the Svyatoi Nos Peninsula, Eastern Baikal Area

The paper reports data on rock and mineral compositions from the Svyatonosskaya Formation, which is a continuation of the Ol’khon Series in the northern part of the Svyatoi Nos Peninsula, eastern shore of Lake Baikal. The pyroxene-amphibole-plagioclase schists (metagabbro) are replaced there by the garnet-biotite-quartz assemblage, which was formed, according to the data of various geothermometers and calculations by the THERMOCALC computer program, under conditions corresponding to the transition from the granulite (848–811°C) to high grades of the amphibolite (715–670°C) facies under high pressures (8.7 ±1.6 kbar). In petrogenetic grids, these conditions fall onto the line of the onset of eclogitization. In nature these rocks are a continuation of the Chernorudskaya-Barakchinskaya zone of elevated pressures in the Ol’khon area. The metasomatic rocks were formed simultaneously with strike-slip faulting, when coupled zones of relatively high-(eclogite-like) and low-pressure (quartzite-marble melange) developed at the inflow of SiO2 and K2O and the removal of MgO and CaO. Analogous compositional changes in gneisses and schists in tectonic extension zones in Ol’khon Island and neighboring areas occurred during the development of migmatites. The migmatization of the gneisses was likely coupled with the garnetization of mafic schists in high-pressure zones and the formation of eclogite-like rocks replacing marbles. The accompanying graphitization of this block suggests that the metasomatic fluid had a hydrocarbon-hydrogen composition.

Long-range propagation of short-period transversal and longitudinal seismic waves in the Baikal zone

Summary In June—October 1979–84 seismographs, recording waves with the prevailing frequency of 8 Hz, have been installed temporarily on the bottom and coasts of Lake Baikal. On quiet days the level of background noise varied from 3 to 4 nm on the west coast and on the deep bottom of the lake to 10 nm on the Ol’khon Island and to 15 nm on the east coast of the lake. The 3–4 nm noise level allowed magnification of the instruments to be kept around 1 million. Seismographs recorded earthquakes with magnitude Ms from -0.3 to +4.5. On average, two and a half seismic events were registered per day. The strongest ones were observed at distances up to 600 km. Compilation of amplitude curves and their comparison with the data available from the literature has shown that in the Baikal zone waves of 8 Hz frequency attenuate with distance not quicker than waves of 2 Hz frequency. Comparison of empirical amplitude curves with theoretical ones, calculated for the adopted velocity sections of the Baikal zone, has resulted in estimates of the quality of the medium equal to Q= 300 for 2 Hz frequency and Q= 1800-2000 for 8 Hz frequency. This phenomenon has some common features with the long-range propagation of Pn and Sn waves on continents and oceans. In the Baikal zone the long-range propagation of high-frequency P- and S-waves can be attributed to the existence of a high-quality wave-guide in the middle part of the Earth's crust, not with low Q, as is usually supposed.