Combined dendrochronological and radiocarbon dating of six Russian icons from the 15th–17th centuries

The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented. The panels of each icon were studied using dendrochronology. Five to six AMS dates were obtained for four icons. Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching. Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.

     

An empirical method to estimate fatalities caused by earthquakes: the case of the Ahar–Varzaghan earthquakes (Iran)

Natural Hazards - The dual Ahar–Varzaghan earthquakes occurred on August 11, 2012, at 16:53 (Iran standard time) in East Azerbaijan province of Iran. The two quakes measured 6.3 and 6.4 on...     

Natural background of hydrocarbon gases (C1–C5) in the waters of the Kara Sea

The distributions of methane and hydrocarbons (HC) C2+ throughout the vertical section of the water mass and sediments of the Kara Sea and the estuaries of the Ob and Yenisei rivers were examine during expeditions aboard the R/V “Akademik Boris Petrov” in 1997–2002. Data obtained during the expeditions and extensive information provided by the complex study of the carbon cycle in the aquatic area were used to analyze the genesis of hydrocarbon gases in marine water. The example of particulate matter was used to demonstrate that hydrocarbon gases of the composition C2–C5 contained in seawater are genetically related to aquatic organic matter (OM), regardless of seawater salinity. The hydrocarbon complex is dominated (80%) by higher C4–C5 homologues. The concentration of C4–C5 hydrocarbons in the estuarine fresh waters is comparable with the high methane concentration (2–3 μl/l), drastically decreases in the zone of water mixing, and then rapidly increases to values several times higher than the methane concentration in seawater outside the outer boundary of the sedimentation depocenter of riverine particulate matter. A direct correlation was established for the concentration of the C4 + C5 homologues with the OM of the water mass, and the leading role was demonstrated to be played by labile OM of the autochthonous biomass (marine phytoplankton) in the genesis of higher hydrocarbon gases (alkenes, alkanes, and isoalkanes) during the early diagenetic stage of OM transformations in water. Along with the biomass of phytoplankton, a significant role in the genesis of C2–C3 hydrocarbons is played by destruction products of terrigenous OM. The destruction of OM and generation of gaseous hydrocarbons, including methane, are restricted to the pycnocline and the water-sediment interface. The absolute predominance of the sum of the C4 + C5 homologues in the hydrocarbon C2+ gases and the presence of unsaturated C2–C4 hydrocarbons are typical of the natural background of hydrocarbons of the Kara Sea water mass.     

Modeling of global climate variations in the 20th–23rd centuries with new RCP scenarios of anthropogenic forcing

Doklady Earth Sciences -     

Causes and effects of the catastrophic flooding on the Siret River (Romania) in July–August 2008

Natural Hazards - As a result of the massive deforestation and windfalling in Romania last year, catastrophic floods frequently occur with historic high-water marks only to be registered every 500...     

Source parameters of earthquakes in the reservoir-triggered seismic (RTS) zone of Koyna–Warna, Western India

New empirical relations are derived for source parameters of the Koyna–Warna reservoir-triggered seismic zone in Western India using spectral analysis of 38 local earthquakes in the magnitude range M _L 3.5–5.2. The data come from a seismic network operated by the CSIR-National Geophysical Research Institute, India, during March 2005 to April 2012 in this region. The source parameters viz. seismic moment, source radius, corner frequency and stress drop for the various events lie in the range of 10¹³–10¹⁶ Nm, 0.1–0.4 km, 2.9–9.4 Hz and 3–26 MPa, respectively. Linear relationships are obtained among the seismic moment (M ₀), local magnitude (M _L), moment magnitude (M _w), corner frequency (fc) and stress drop (?σ). The stress drops in the Koyna–Warna region are found to increase with magnitude as well as focal depths of earthquakes. Interestingly, accurate depths derived from moment tensor inversion of earthquake waveforms show a strong correlation with the stress drops, seemingly characteristic of the Koyna–Warna region.     

On wave–current interaction by the Green–Naghdi equations in shallow water

This work is on the use of the Green–Naghdi (GN) nonlinear wave equations for simulating wave–current interaction in shallow water. The stream-function wave theory is used at the wave-maker boundary to generate nonlinear incident waves to consider the wave–current interaction. The nonlinear GN equations are solved in the time domain by use of the finite-difference method. The model is evaluated with data from three experimental studies. A strong opposing current over a submerged bar is investigated in the first test case. In the second test case, the interaction of waves with a uniform current over flat bottom is considered. In the third case, wave–current interaction over a variable bathymetry with the following and opposing currents is studied. The numerical results obtained by the GN equations are compared with the experimental data and results based on the Boussinesq equations. A good agreement is obtained for the three experimental studies considered for a wide range of wave and current conditions.     

Historical and contemporary aspects of pluriactivity in the Curvature Sub–Carpathians of Romania

This paper focuses on the Curvature Sub–Carpathians, especially with respect to Buzau County. The region as a whole has always been relatively well-settled and agriculture has usually been combined with a range of local industrial and handicraft employments. A study of traditional domestic activities brings out a close connection between specific natural resources and characteristic features of traditional peasant household work. The Prahova Valley has been particularly favoured on account of the oil industry and a major transport axis connecting Bucharest with Brasov via Ploiesti, but elsewhere industry did not spread extensively beyond the county centres (Buzau, Focsani, Pitesti and Targoviste) and their immediate environs such as Colibasi and Doicesti. During the present transition phase the rural population is struggling to survive by combining elements of the modern and traditional economies. The main rural centres are relatively well off while the outlying villages are experiencing severe poverty problems. Apart from brandy distilling, traditional rural industries are no longer viable, although alternative systems of pluriactivity are under discussion. This revised version was published online in July 2006 with corrections to the Cover Date.     

Geochemical background of potentially toxic trace elements in reclaimed soils of the abandoned pyrite–uranium mine (south-central Poland)

Spatial distribution patterns of As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, U and Zn were determined in topsoil samples collected after 40 years of chemical remediation conducted in the inoperative “Staszic” pyrite–uranium mine in the Holy Cross Mountains, south-central Poland. Soil samples were taken from 58 sites using a systematic random sampling design. Selected samples were subjected to an X-ray diffractometry analysis on bulk soils and separated clay fractions. Hematite, goethite and gypsum are common mineral phases in soil samples. Technogenic soils developed on reclaimed mine spoils show uniform spatial element distribution patterns and additionally a distinct enrichment in As, Pb, Mn, U and Zn. Mineral and chemical composition of soils vs. rocks points to the lithogenic source of the determined elements. The results of chemical analysis have been used for evaluation of geochemical background of trace elements in the study area with the iterative 2σ-technique. This investigation shows that using mean crustal element concentrations (Clarke values) as proxies of threshold values in soils are not useful for determination of strongly positive geochemical anomalies. A modified enrichment factor, i.e. a local enrichment factor, is proposed for identification of sites where soils are contaminated.     

Modelling the occurrence of gullies at two spatial scales in the Olteţ Drainage Basin (Romania)

Gully erosion is both a significant natural hazard and an important sediment source. The design of proper prevention measures relies firstly on the prediction of the future locations of gullies. But, as recent progress has shown, methods and results in any environmental modelling greatly depend upon scale, the selection of which should be based on management needs. This research deals with predicting the spatial potential for gullying at two different scales grouped in a top-down framework, i.e. starting with a preliminary, regional scale analysis (1:100,000–1:200,000) to develop a simplified model, and performing a more detailed, intermediate level analysis at a medium scale (1:25,000–1:50,000) for the basin sector revealed as the most threatened by the process. At the same time, the study searches for relationships among: scale of analysis, area of investigation, precision and accuracy of input data, and the quality of expected results and their applicability. The study area is the Olteţ Drainage Basin (2439 km²) in southern Romania, which extends over four landform types: mountains, hills, a plateau (piedmont) and a plain. Aiming to investigate the scale effect, the same statistical method is selected for both analyses, namely Classification and Regression Trees (CART). Scale-adapted procedures and resolutions are applied for defining the dependent variable, deriving the environmental attributes and deciding the sampling strategy needed to provide information for the statistical analyses. In order to detect the degree of gullying at the regional scale, the statistical method is used over the entire basin, and gully density is selected as the target variable. For the analysis of gully susceptibility at the medium scale, within the most affected area of the Olteţ Basin identified as the piedmont sector, the single gully and the intensely gullied spot are defined as the target variables. The best validated maps obtained at the two scales are compared. The results reveal that both individual maps are characterized by statistical accuracy (a NRMSE value of 0.05–0.08 and an AUC of 0.86 for the regional scale and the medium scale models, respectively). Yet, the regional scale map is affected by high uncertainties when compared to the medium scale one. The scale dependency of results and hence the relative nature of their accuracy and reliability are highlighted in the context of both fundamental and applied research.

     

Estimating tsunami potential of earthquakes in the Sumatra–Andaman region based on broadband seismograms in India

In this paper, we report that the ratio of broadband energy (0.01?C2?Hz) to high-frequency energy (0.3?C2?Hz), E _r, estimated from regional seismograms of India, might be a useful parameter in estimating tsunami potential of earthquakes in the Sumatra?CAndaman region. E _r is expected to be sensitive to the depth as well as to the source characteristics of an earthquake. Since a shallow and slow earthquake has a greater tsunamigenic potential, E _r may be a useful diagnostic parameter. We base our analysis on broadband seismograms of the great earthquakes of Sumatra?CAndaman (2004, M _w?~?9.2) and Nias (2005, M _w 8.6), 41 of their aftershocks, and the earthquakes of north Sumatra (2010, M _w 7.8) and Nicobar (2010, M _w 7.4) recorded at VISK, a station located on the east coast of India. In the analysis, we also included the two recent, great strike-slip earthquakes of north Sumatra (2012, M _w 8.6, 8.2) recorded at VISK and three south Sumatra earthquakes (2007, M _w 8.5; 2007, M _w 7.9; 2010, M _w 7.8) recorded at PALK, a station in Sri Lanka. We find that E _r is a function of depth; shallower earthquakes have higher E _r values than the deeper ones. Thus, E _r may be indicative of tsunamigenic potential of an earthquake. As M _w and E _r increase so does the tsunami potential. In addition to the parameter E _r, the radiated seismic energy, E _s, may be estimated from the regional seismograms in India using empirical Green??s function technique. The technique yields reliable E _s for the great Sumatra and Nias earthquakes. E _r and E _s computed from VISK data, along with M _w and focal mechanism, may be useful in estimating tsunami potential along the east coast of India from earthquakes in the Sumatra?CAndaman region in less than ~20?min.     

Stratigraphic and geochemical study of the organic-rich black shales in the Tarcău Nappe of the Moldavidian Domain (Carpathian Chain,Romania)

An integrated stratigraphic analysis has been made of the Tarcău Nappe (Moldavidian Domain, Eastern Romanian Carpathians), coupled with a geochemical study of organic-rich beds. Two Main Sequence Boundaries (Early Oligocene and near to the Oligocene–Aquitanian boundary, respectively) divide the sedimentary record into three depositional sequences. The sedimentation occurred in the central area of a basin supplied by different and opposite sources. The high amount of siliciclastics at the beginning of the Miocene marks the activation of the “foredeep stage”. The successions studied are younger than previously thought and they more accurately date the deformation of the different Miocene phases affecting the Moldavidian Basin. The intervals with black shales identified are related to two main separate anoxic episodes with an age not older than Late Rupelian and not before Late Chattian. The most important organic-rich beds correspond to the Lower Menilites, Bituminous Marls and Lower Dysodilic Shales Members (Interval 2). These constitute a good potential source rock for petroleum, with homogeneous Type II oil-prone organic matter, highly lipidic and thermally immature. The deposition of black shales has been interpreted as occurring within a deep, periodically isolated and tectonically controlled basin.     

A combined experimental study of vivianite and As (V) reactivity in the pH range 2–11

Four different sets of experiments were completed in order to constrain vivianite [Fe₃(PO₄)₂ · 8H₂O] reactivity under conditions pertinent to As(V)-bearing groundwater systems. Firstly, titration experiments were undertaken in the pH range 4-9 to determine the zero point of charge (ZPC) of vivianite; showing that the ZPC lies at a pH of approximately 5.3. Secondly, the steady state dissolution rates of vivianite far from equilibrium were measured in aqueous solutions in the pH range 2–10 at 18.5 ^°C (±3 °C) using a fluidized bed reactor. The rate of vivianite dissolution, R, is given by     

Change in carbon flux (1960–2015) of the Red River (Vietnam)

Global riverine carbon concentrations and fluxes have been impacted by climate and human-induced changes for many decades. This paper aims to reconstruct the longterm carbon concentrations and carbon fluxes of the Red River, a system under the coupled pressures of environmental change and human activity. Based on (1) the relationships between particulate and dissolved organic carbon (POC, DOC) or dissolved inorganic carbon (DIC), and suspended sediments (TSS) or river water discharge and on (2) the available detailed historical records of river discharge and TSS concentration, the variations of the Red River carbon concentration and flux were estimated for the period 1960–2015. The results show that total carbon flux of the Red River averaged 2555?±?639 kton C year^?1. DIC fluxes dominated total carbon fluxes, representing 64% of total, reflecting a strong weathering process from carbonate rocks in the upstream basin. Total carbon fluxes significantly decreased from 2816 kton C year^?1 during the 1960s to 1372 kton C year^?1 during the 2010s and showed clear seasonal and spatial variations. Organic carbon flux decreased in both quantity and proportion of the total carbon flux from 40.9% in 1960s to 14.9% in 2010s, reflecting the important impact of dam impoundment. DIC flux was also reduced over this period potentially as a consequence of carbonate precipitation in the irrigated, agricultural land and the reduction of the Red River water discharge toward the sea. These decreases in TSS and carbon fluxes are probably partially responsible for different negatives impacts observed in the coastal zone.     

Change trend of natural gas hydrates in permafrost on the Qinghai-Tibet Plateau (1960–2050) under the background of global warming and their impacts on carbon emissions

Global warming and the response to it have become a topic of concern in today’s society and are also a research focus in the global scientific community. As the world’s third pole, the global warming amplifier, and the starting region of China’s climate change, the Qinghai-Tibet Plateau is extremely sensitive to climate change. The permafrost on the Qinghai-Tibet Plateau is rich in natural gas hydrates (NGHs) resources. Under the background of global warming, whether the NGHs will be disassociated and enter the atmosphere as the air temperature rises has become a major concern of both the public and the scientific community. Given this, this study reviewed the trend of global warming and accordingly summarized the characteristics of the temperature increase in the Qinghai-Tibet Plateau. Based on this as well as the distribution characteristics of the NGHs in the permafrost on the Qinghai-Tibet Plateau, this study investigated the changes in the response of the NGHs to global warming, aiming to clarify the impacts of global warming on the NGHs in the permafrost of the plateau. A noticeable response to global warming has been observed in the Qinghai-Tibet Plateau. Over the past decades, the increase in the mean annual air temperature of the plateau was increasingly high and more recently. Specifically, the mean annual air temperature of the plateau changed at a rate of approximately 0.308–0.420°C/10a and increased by approximately 1.54–2.10°C in the past decades. Moreover, the annual mean ground temperature of the shallow permafrost on the plateau increased by approximately 1.155–1.575°C and the permafrost area decreased by approximately 0.34×10⁶ km² from about 1.4×10⁶ km² to 1.06×10⁶ km² in the past decades. As indicated by simulated calculation results, the thickness of the NGH-bearing permafrost on the Qinghai-Tibet Plateau has decreased by 29–39 m in the past 50 years, with the equivalent of (1.69 – 2.27)×10¹⁰–(1.12–1.51)×10¹² m³ of methane (CH₄) being released due to NGHs dissociation. It is predicted that the thickness of the NGH-bearing permafrost will decrease by 23 m and 27 m, and dissociated and released NGHs will be the equivalent of (1.34–88.8)×10¹⁰ m³ and (1.57–104)×10¹⁰ m³ of CH₄, respectively by 2030 and 2050. Considering the positive feedback mechanism of NGHs on global warming and the fact that CH₄ has a higher greenhouse effect than carbon dioxide, the NGHs in the permafrost on the Qinghai-Tibet Plateau will emit more CH₄ into the atmosphere, which is an important trend of NGHs under the background of global warming. Therefore, the NGHs are destructive as a time bomb and may lead to a waste of efforts that mankind has made in carbon emission reduction and carbon neutrality. Accordingly, this study suggests that human beings should make more efforts to conduct the exploration and exploitation of the NGHs in the permafrost of the Qinghai-Tibet Plateau, accelerate research on the techniques and equipment for NGHs extraction, storage, and transportation, and exploit the permafrost-associated NGHs while thawing them. The purpose is to reduce carbon emissions into the atmosphere and mitigate the atmospheric greenhouse effect, thus contributing to the global goal of peak carbon dioxide emissions and carbon neutrality.©2022 China Geology Editorial Office.     

Tracking footprint of hydrogeology research in China via scientific projects funded by the NSFC (1997–2013)

In order to track the footprint of the hydrogeology research in China during the past years, all the projects with the code of D0213 (hydrogeology, geothermic geosciences included) funded by the National Natural Science Foundation of China (NSFC) from 1997 to 2013 were searched and analysed. The statistics results showed that, a total of 88 institutes were ever funded with a total of 462 projects with the gross amount of 214 million yuan, and Beijing and Wuhan were the two most important centres for the hydrogeology research. In detail, A few 211 Project & 985 Project universities were the main forces, followed by Chinese Academy of Geological Sciences and Chinese Academy of Sciences. Apart from the several traditional geological universities/colleges (China University of Geosciences (Wuhan), China University of Geosciences (Beijing), Nanjing University, Jilin University, and Chang’an University) with outstanding performances, a few new forces from 211 Project & 985 Project universities also made good achievements with Beijing Normal University and Peking University standing out. Generally speaking, the focused scientific issues and related technologies included that but were not limited to, (1) Mechanism, control and remediation of groundwater/soil pollution were the most active fields, (2) Flow dynamics in saturated/unsaturated zone was still an interested topic, (3) Groundwater in hydrological cycle in different scales under climate change and human activities developed very quickly, (4) Engineering problems and disasters associated with groundwater aroused enormous attention, (5) Numerical modeling was still the most important means with wide application, and (6) Environmental tracing was a very active technique and new tracers were found and tried frequently