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Late Holocene histories of vegetation, human activity, and climate inland of the Nobi Plain, central Japan, were investigated using pollen, charcoal, and chronological (radiocarbon and pottery) analyses of the Arao-Minami archaeological sediment layers. This site was home to a large regional community from the Yayoi to Kofun periods. Agricultural production of buckwheat began before the Middle Yayoi (∼200 BC). Cultivated Poaceae increased in the warm period at ca. 2.2–1.7 cal ka BP (ca. 250 BC to ca. 250 AD), based on the pollen-based climate indices. This can be regarded as intensified wet rice agriculture occurring at this period because the archaeological examinations report the existence of paddy-field remains and rice phytoliths from the Late Yayoi to Early Kofun. This period approximately corresponds to the Roman Warm Period. Primary natural forests, such as Quercus subg. Lepidobalanus , Quercus subg. Cyclobalanopsis , Cupressaceae, and Cryptomeria , as well as cultivated Poaceae gradually decreased from ca. 1.7 to ca. 1.2 cal ka BP (ca. 250 AD to 750 AD), which corresponds to the Dark Age Cold Period. In contrast, an expansion of Pinus conifer forests and temporal rises of accumulation rates occurred in this period. Based on the evidences, we propose that the agriculture at this site temporarily changed to slash-and-burn cultivation at a nearby mountain, associated with the cold climate. In the warm period from ca. 1.2 cal ka BP (ca. 750 AD), cultivated Poaceae increased again, suggesting a return to wet rice agriculture around the site. In this paper, we conclude that ancient people who lived inland of the Nobi Plain adapted to global climate changes. [ABSTRACT FROM AUTHOR]

Rationale: Preparation of BaSO4 from samples of atmospheric rain, snow, and aerosols has been used for δ18O and δ34S analyses. In the present study, we investigated the effect of various sample pretreatments on δ18O and δ34S values determined from a Na2SO4 reagent solution and samples of atmospheric precipitation to improve assay time and cost efficiency. Methods: BaSO4 was prepared from a Na2SO4 solution by (a) evaporative concentration, (b) evaporation to dryness, (c) evaporation to dryness after adding HCl, and (d) evaporation to concentration after adding HCl, followed by cooling and then precipitation using a BaCl2 solution. To analyze the atmospheric precipitation samples for δ18O, BaSO4 prepared from the samples was treated with diethylenetriaminepentaacetic acid (DTPA) and SO42− and separated chromatographically. The values of δ18O and δ34S were measured using a continuous‐flow elemental analyzer coupled to an isotope‐ratio mass spectrometer. Results: The δ34S values in BaSO4 precipitated from Na2SO4 solution determined by methods (a)–(c) were consistent within precisions of ±0.5‰. The δ18O values of methods (a) and (b) were consistent within ±0.2‰, whereas the δ18O values of methods (c) and (d) increased with increasing HCl concentrations. Similar results were obtained from samples of atmospheric precipitations. The δ18O values from DTPA‐treated BaSO4 were consistent with those obtained by chromatographic separation within ±0.5‰. Conclusions: We found no significant differences in the effects of various pretreatments (acidification, heating, concentration, and drying) on δ18O and δ34S values in sulfate from samples of atmospheric precipitation and aerosols extracted as BaSO4 if HCl was not added to the sample before heating and BaSO4 was treated with DTPA for the δ18O analysis. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of aromatic or benzylic disulfides with 2.5 equiv of Selectfluor™ in acetonitrile/water (10:1) at room temperature efficiently produced the corresponding thiosulfonates. Conversely, the reaction of disulfides with 6.5 equiv of Selectfluor™ or thiosulfonates with 4.5 equiv of Selectfluor™ in refluxing acetonitrile/water (10:1) provided sulfonyl fluorides in high yields. Accufluor™ and FP-T300™ are also effective in preparing sulfonyl fluorides from disulfides under the similar reaction conditions. Sulfonyl chlorides or sulfonyl bromides were effectively obtained from the reaction of disulfides with 6 equiv of either N-chlorosuccinimide or N-bromosuccinimide in acetonitrile/water (10:1) at room temperature. Some other electrophilic chlorinating or brominating reagents are also able to be used instead of N-chlorosuccinimide or N-bromosuccinimide for the syntheses of sulfonyl halides from disulfides. These reactions of disulfides with electrophilic halogenating reagents are convenient methods to prepare thiosulfonates and sulfonyl halides. [Copyright &y& Elsevier]

Abstract: The reaction of aromatic or benzylic disulfides with 2.5equiv of Selectfluor™ in acetonitrile/water (10:1) at room temperature efficiently produced the corresponding thiosulfonates. On the other hand, the reaction of disulfides with 6.5equiv of Selectfluor™ in refluxing acetonitrile/water (10:1) provided sulfonyl fluoride in high yields. [Copyright &y& Elsevier]

Past and ongoing precipitations of Mn-carbonate (rhodochrosite) have occurred in the freshwater Lake Ohnuma, which is situated about 8 km south of the Hokkaido-Komagatake volcano, southwest Hokkaido (northern Japan). Lake sediments from a surface and a longer ∼4 m core contain the sedimentary rhythms of rhodochrosite laminae and volcanic deposits which were identified by nondestructive micro-XRF fluorescence analyses. The three tephra ash layers from the Hokkaido-Komagatake volcano, characterized by peaks of Al, Si, K, Ca, and Ti, correspond to regionally recognized tephras (1640, 1929 and 1996 CE) based on ashfall isopachs and 137Cs, 210Pb and 14C ages determined from the two cores. The sedimentation rate showed a drastic change around 1929 CE; ∼0.3 cm/yr for 1640–1929 CE and ∼2.7 cm/yr for 1929–2012 CE. The Mn content record of Lake Ohnuma sediments, composed of rhodochrosite laminae, showed a periodic variation with a decadal–centennial scale over the interval 1640–2012 CE. Sediment petrography and hydrochemical measurements suggest that the metastable phase of rhodochrosite was deposited during summer after being precipitated, followed by the crystal growth of rhodochrosite within the anoxic sediments. On the basis of these results, high Mn content is interpreted as an indicator of strengthened summer stratification associated with reduced rainfall runoff. The Ti/Si ratios are representative of the relative abundance of detrital inputs from the watershed. The combined signals of elevated Mn content and Ti/Si ratio for 1935–2012 CE indicate eutrophication and hypoxia in the lake and enhanced land erosion in the watershed, associated with the post-1970s intensive land use such as livestock farming. For 1640–1935 CE, the Lake Ohnuma record shows an antiphase relationship between the Mn content and Ti/Si ratio, which implies that the detrital inputs reflected the strength of the East Asian summer monsoon (EASM), and the reduced rainfall runoff resulted in weaker mixing, followed by depleted O 2 in the water column. The antiphase variation in Mn content and Ti/Si ratio suggest weak EASM during the Little Ice Age (∼1850 CE), followed by strong EASM between 1860 and 1929 CE. • Lake Ohnuma sediments contain Ko-d (1640 CE), Ko-a (1929 CE), and 1996 CE tephra deposits. • These deposits originated from the Hokkaido-Komagatake volcano. • Sediments recorded EASM over 1640–1935 CE, then anthropogenic signals over 1935–2012 CE. • Rhodochrosite is precipitated in hypoxic hypolimnion during summer stratification. • Rhodochrosite laminae formation coincides with weaker EASM precipitation phases. [ABSTRACT FROM AUTHOR]

Micro-beam X-ray fluorescence (XRF) scanning spectroscopy is very useful for analyzing heterogeneous samples from earth and environmental sciences with high spatial resolution. However, XRF intensity depends on grain size and mineralogical composition, known as the heterogeneous effect, although little quantitative evaluation has been conducted. In this study, the binary powdered mixtures of Fe 2 O 3 in the CaCO 3 or SiO 2 matrix with nine grain size fractions (0.3–605 μm), four Fe 2 O 3 concentrations (5–20 wt%), and fine-grained sedimentary cores from Lake Baikal were used for analysis, using a scanning X-ray analytical microscope (SXAM), and then evaluated by making a simple modification of the Berry–Furuta–Rhodes model. The results of binary powdered samples show that the Fe intensity decreases as the grain size increases, but if the grain size is constant, its intensity has a linear relationship with the composition of Fe 2 O 3. The experimental data are in good agreement with theoretical curves. The theory predicts that if a phase that contains fluorescent elements has narrow ranges of concentration and grain size, the micro-beam XRF spectroscopy enables highly precise calibration from the XRF intensity to element concentration. The theoretical curves of the Lake Baikal sediment core suggest that the Fe intensity has about a 30% maximum difference in the median grain size range of 3.9–28.2 μm. This variation appears in a scatter of regression between Fe intensity and concentration, but it scarcely affected the XRF intensity variability of sediment composition. [Display omitted] • Theory predicts that the heterogeneity effect appears in grain sizes of 1–1000 μm. • Finer grains with a narrow content range allow precise XRF scanning spectroscopy. • The effect causes scatter between XRF intensity and element concentration. • XRF intensity reflects sediment composition rather than grain size variation. [ABSTRACT FROM AUTHOR]

In the late ninth century, the northern Yatsugatake volcanoes in central Japan experienced a catastrophic collapse, simultaneously causing a debris-avalanche. Such failures have been related to the AD 887 Nin'na earthquake, which occurred along the Nankai Trough. However, supportive evidence of the hypothesis remains unavailable. The present study reports wiggle match radiocarbon (14C) dating of a buried tree excavated from a deep part of the debris deposit. The death year of the buried tree was dated as AD 838 ± 17. The date exactly matches an inference of the AD 887 earthquake obtained from historical documents and field records of archaeological ruins, considering that 14C ages of Japanese trees have a regional offset of ≈30 years greater than the IntCal dataset. Our result suggests that the AD 887 earthquake occurred along about 700 km extending from the western margin of the Nankai Trough to the central segment of the Itoigawa-Shizuoka Tectonic Line. • A buried tree was obtained from deep debris-avalanche deposit in Mt. Yatsugatake. • Wiggle match radiocarbon (14C) dating was conducted for the buried tree-ring. • Death year of tree was dated as AD 838 ± 17. • The years is consistent with AD 887 earthquake, considering ≈30 years offset in Japan. • AD 887 earthquake occurred along about 700 km from Nankai Trough to central ISTL. [ABSTRACT FROM AUTHOR]

This study investigated a continuous sediment core, retrieved from the deepest part in Lake Hovsgol, northwestern Mongolia. Its surrounds are occupied by a continuous Siberian permafrost zone. Distinct geochemical and lithological features suggest that the watershed soil was moistened during the last deglaciation, associated with climate amelioration. Especially, the calcareous glacial clay layers (ca 13.7 and ca 11.0 cal. ka BP), with high sulfur content peaks and positive shifts of δ34S values, well correlate with the timing of meltwater pulses 1A and 1B, leading to rapid warming such as Bølling/Allerød and Preboreal Holocene, respectively. This finding allows our interpretation for the calcareous glacial clay layers produced by landslide‐induced debris flow, which resulted from intensive water discharge from rapid thawing of permafrost during the abrupt warming periods. Our correlation with Lake Baikal records suggests that these permafrost thawings have accelerated over the area of the Selenga drainage basin (continental interior Eurasia). Key Points: The high TS contents with positive δ34S anomalies in sediments of lakes in permafrost zones become an indicator of permafrost thawingRapid thawing of Siberian permafrost during the last deglaciation occurred over the Selenga drainage basin (continental interior Eurasia)Thawing of Siberian permafrost was accelerated at ca 13.7 and ca 11.0 cal. ka BP, which correspond to Bølling/Allerød and Preboreal Holocene [ABSTRACT FROM AUTHOR]

Micro‐X‐ray fluorescence scanning spectroscopy of marine and lake sedimentary sequences can provide detailed palaeoenvironmental records through element intensity proxy data. However, problems with the effects of interstitial pore water on the micro‐X‐ray fluorescence intensities have been pointed out. This is because the X‐ray fluorescence intensities are measured directly at the surfaces of split wet sediment core samples. This study developed a new method for correcting X‐ray fluorescence data to compensate for the effects of pore water using a scanning X‐ray analytical microscope. This involved simultaneous use of micro‐X‐ray fluorescence scanning spectroscopy and an X‐ray transmission detector. To evaluate the interstitial pore water content from the X‐ray transmission intensities, a fine‐grained sediment core retrieved from Lake Baikal (VER99‐G12) was used to prepare resin‐embedded samples with smooth surfaces and uniform thickness. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert–Beer law, enabled calculation of the interstitial pore spaces and their resin content with high reproducibility. The X‐ray fluorescence intensities of resin‐embedded samples were reduced compared with those of dry sediment samples because of: (i) the X‐ray fluorescence absorption of resin within sediment; and (ii) the sediment dilution effects by resin. An improved micro‐X‐ray fluorescence correction equation based on X‐ray fluorescence emission theory considers the instrument's sensitivity to each element, which provides a reasonable explanation of these two effects. The resin‐corrected X‐ray fluorescence intensity was then successfully converted to elemental concentrations using simple linear regression between the data from micro‐X‐ray fluorescence scanning spectroscopy and from the conventional analyzer. In particular, the calculated concentration of SiO2 over the depth of the core, reflecting diatom/biogenic silica concentration, was significantly changed by the calibrations, from a progressively decreasing trend to an increasing trend towards the top of the core. [ABSTRACT FROM AUTHOR]

Abstract Chemical and radiocesium concentrations in water and riverbed tufa of the Nigori River, flowing out of the southern foot of Mt. Asama volcano in central Japan, were investigated following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. This tufa is characterized by porous and dense laminae. Its annual lamination (varve) is formed by seasonal changes in dissolved CO 2 concentration in water with temperature, and the tufa calcite is mostly precipitated during summer. We analyzed radiocesium concentrations in ∼4-mm-thick tufa samples that included four or five varves collected after the fall in 2011–2014. The activity ratio of 134Cs/137Cs in tufa collected in 2011 and 2014 was 0.96 ± 0.01 and 0.99 ± 0.01, respectively, which implies radiocesium generated as a result of the FDNPP. Sequential extractions indicate that 137Cs in tufa collected in 2011 is occupied in exchangeable and carbonate phases (55.2% and 44.8%, respectively). The 137Cs concentrations equivalent to tufa calcite that were precipitated after 2011 showed variations similar to the amount of summer rainfall during 2011–2014, which may be attributed to increases in dissolved 137Cs concentrations in river water associated with intensified rainfall and microbial action over the summer. In contrast, the 137Cs sorbed to tufa calcite was not retained in the riverbed, and its migration may be attributed to the porous texture of tufa and the high flow rate of the river. Therefore, tufa calcite is easier to dissolve even though it adsorbs compared with other minerals (mica, andosol etc.). Highlights • 137Cs behavior during natural calcite precipitation was investigated for the first time. • The radiocesium were generated as a result of the Fukushima Daiichi Nuclear Power Plant accident. • 137Cs concentrations in tufa calcite possibly depend on amount of summer rainfall. • 137Cs sorbed to tufa calcite was not mostly retained until next summer. [ABSTRACT FROM AUTHOR]

Paleoenvironmental and paleoclimate changes in intracontinental Siberia were reconstructed by continuous, high-resolution records (biogenic silica, U, total organic carbon and N, total S, and grain size) from a sediment core retrieved from the Buguldeika Saddle, Lake Baikal, dating back to the last 33 cal. ka BP. The Holocene climate was wet relative to the last glacial period. The climate became gradually warm and wet from the early to middle Holocene, followed by a shift at ca. 6.5 cal. ka BP toward warm and dry, possibly because of evapotranspiration. This suggests that the climate system transition from the glacial to interglacial state occurred at that time. In the last glacial, the deposition of carbonate mud from the Primorsky Range was associated with Heinrich events (H3 and H1) and the Selenga River inflow during the Last Glacial Maximum was caused by meltwater of mountain glaciers in the Khamar–Daban Range. The anoxic bottom-water during the Allerød-Younger Dryas was probably a result of weakened ventilation associated with reduced Selenga River inflow and microbial decomposition of organic matters originating from moderate input of nutrients from the Primorsky Range. The rapid decline in precipitation during the early Holocene may have been a response to the 8.2 ka cooling event. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of dithioacetals with 30% hydrogen peroxide in the presence of catalytic amounts of tantalum(V) and iodide ion effectively produced carbonyl compounds in high yields. Dithioacetals also can be deprotected using the niobium(V) catalyzed oxidation of iodide ion by hydrogen peroxide under mild conditions. [Copyright &y& Elsevier]

Abstract: The aerobic oxidation of ditertiary glycols catalyzed by oxytrichlorovanadium resulted in carbon–carbon bonds cleavage producing the ketones efficiently. [Copyright &y& Elsevier]

Abstract: Tantalum(V) and niobium(V) are effective catalysts for the oxidation of sulfides with 30% hydrogen peroxide. The reaction of sulfides with 30% hydrogen peroxide catalyzed by tantalum(V) chloride or niobium(V) chloride in acetonitrile, i-propanol or t-butanol selectively provided the corresponding sulfoxides in high yields. The corresponding sulfones are efficiently obtained from the reaction of sulfides with 30% hydrogen peroxide in methanol catalyzed by tantalum(V) or niobium(V). [Copyright &y& Elsevier]

The article presents steps of the chemical equations involved in the oxidation of dithioacetals.

A range of functional groups is inert and unaffected under these reaction conditions. [ABSTRACT FROM AUTHOR]