The history of the East Asia winter monsoon (EAWM) and its forcing mechanisms remain elusive due to conflicting reconstructions. In this study, we attempt to quantify changes in interglacial winter ...monsoon intensity over tropical East Asia, based on reconstructions from the southern South China Sea (SCS) and model outputs from transient simulations (TRACE-21). The new monsoon record is derived from individual-specimen δ18O of planktonic foraminifera, the variability of which is dominated by the seasonality of sea surface temperature and thus the intensity of the EAWM over the SCS. The standard deviation of individual-specimen δ18O shows a gradual decrease from 0.61 to 0.20 and from 0.49 to 0.25 across marine isotope stages (MISs) 5e and 1, respectively, indicating a decline of the EAWM intensity along with precessional changes. Reconstructions and simulations together constrain a 15% decrease of the EAWM intensity over the Holocene, and a more substantial weakening over the MIS 5e. Precessional forcing of the interglacial EAWM variations over the SCS can be mainly explained by two mechanisms. First, a persistent increasing of boreal winter insolation can reduce the temperature gradient between Asian inlands and the Pacific, weakening the entire winter wind field over East Asia. Second, precessional forcing gave rise to an increasing El Niño frequency and magnitude over the Holocene, which facilitated the establishment of an anomalous anticyclonic circulation over the tropical West Pacific and thus reduced the northerly winter winds. Contrary to traditional views, the retreat of the Northern Hemisphere ice sheets during early interglacial periods did not contribute to changes in the tropical EAWM. In addition, model outputs have also explicitly revealed that the mid-latitude and the tropical EAWM systems respond differently to a set of forcing factors, suggesting a spatial discrepancy of the EAWM evolution in the past.
•Reliable monsoon reconstruction based on spreading of single-specimen oxygen isotopes.•Transient simulations give clear mechanisms for winter monsoon evolution.•Boreal winter insolation determines wind intensity via altering temperature gradient.•A tight correlation between tropical winter monsoon and ENSO dynamics.
There is much debate regarding the temporal and spatial pattern of hydroclimate variations on the Tibetan Plateau during the Holocene, focusing especially on the dipolar pattern of precipitation and ...moisture between the southern and northern regions, on multiple timescales. Modern observations reveal that the δ18O in precipitation is an integrated tracer of the atmospheric processes of the Indian summer monsoon (ISM), the East Asian summer monsoon (EASM), and the westerlies, which dominate the climate of the Tibetan Plateau. Here, we summarize and compare 20 Holocene lacustrine authigenic carbonate δ18O records from lakes distributed across the Tibetan Plateau. After carefully considering the potential effects of temperature, evaporation, site elevation, meltwater supply, and moisture sources, we eliminate their influences on the isotopic composition of Tibetan lakes, and suggest that the long-term variations of the lacustrine δ18O records were dominated by the moisture sources. The δ18O values of the lake sediments in the central and western Tibetan Plateau increased since the early Holocene, which agrees with the trend of δ18O in speleothem records from the plateau, as well as with the variations of monsoon precipitation reconstructions for the region. Overall, this evidence indicates the substantial influence of the monsoon in the abovementioned regions. However, the δ18O records from lakes in the northeastern Tibetan Plateau show a decreasing trend during the second half of the Holocene (after ∼5 ka), highlighting the operation of a different hydrological process, with enhanced moisture availability, in the regions. It has been suggested that the increased contribution from westerlies-derived moisture in the non-monsoon season, with depleted δ18O (e.g., from melting snow or frozen soil in spring), is responsible for such variations. We propose that the interplay between the Asian summer monsoon and the westerlies was the major control of the hydroclimatic variations on the Tibetan Plateau during the Holocene, which led to the dipolar pattern of moisture variation between the northeastern Tibetan Plateau and other parts of the plateau, on the multi-millennial timescales during the Holocene.
Although Holocene-scale trends in Indian Summer Monsoon (ISM) variability have been well-established, manifestations and drivers of centennial- and multi-decadal-scale variability are still debated. ...Additionally, the extent to which proxies reflect abrupt climatic changes rather than proxy-specific thresholds is unclear. To address these questions, we summarize a 9200-year record from Yilong Lake in Yunnan China using multiple proxies including oxygen and carbon isotopes of authigenic calcite as well as Ti/Al ratio to characterize lake hydrologic balance and catchment erosion, respectively. We compare these results to two other well-studied nearby lakes on the Yunnan Plateau. At all three lakes, the Holocene-scale waning of the ISM is evident, but punctuated by abrupt shifts indicative of lower precipitation and/or greater evaporation at 7900, 5500, and 4500 cal yr B.P. We suggest that a shift to a positive mean-state of the Indian Ocean Dipole lasting multiple centuries can account for these events, with possible moderating influence from El Niño Southern Oscillation. After 1500 cal yr B.P., Yilong oxygen isotopes shift to less negative values as a result of human manipulation of hydrologic balance, coincident with the deposition of a red clay layer from catchment erosion. These results are similar to other Yunnan lakes although the intensity of anthropogenic management of Yilong's hydrologic balance is substantially smaller than at the other regional lakes. These results underscore the diversity of anthropogenic impacts to lakes, even ones that are only a few kilometers apart, and demonstrate spatiotemporal differences in freshwater resource use.
•A 9200-year lacustrine archive of the Indian Summer Monsoon.•Abrupt weakening of the monsoon at 7900, 5500, and 4500 years BP.•Synchronous events recorded in three lake oxygen isotope records.•Possible role of Indian Ocean Dipole in forcing abrupt events.•Anthropogenic influence after 1500 years BP.
Kawasaki disease (KD) is a multi-systemic vasculitis of unknown etiology that occurs mainly in children, and the disturbance of gut microbiota is generally believed to cause a hyperimmune reaction ...triggering KD. The aim of the study was to investigate the alterations in the fecal microbiota and assess its relationship with systemic inflammation. Totally 30 KD children were enrolled and followed up for 6 months, with another group of 30 age- and sex-matched healthy children as controls. Phylotype profiles of fecal microbial communities were analyzed using 16S rRNA gene sequencing. Serum inflammatory markers were detected by flow cytometer. We showed that KD children exhibited a significant reduction in fecal microbial diversity in the acute phase compared with the healthy controls. Enterococcus, Acinetobacter, Helicobacter, Lactococcus, Staphylococcus and Butyricimonas in acute KD children were significantly higher than the healthy children. Levels of systemic inflammation biomarkers, including IL-2, IL-4, IL-6, IL-10, TNF-α, and INF-γ, were significantly elevated in the acute KD children. Altered microbiota genera Enterococcus and Helicobacter abundances were shown to be correlated positively with IL-6, which were never previously reported in KD. This study suggested that gut microbiota alteration is closely associated with systemic inflammation, which provides a new perspective on the etiology and pathogenesis of KD.
Accelerated soil erosion and trace metal pollution in aquatic environments have become a pervasive aspect of global environmental changes during the Anthropocene, threatening food security and ...ecosystem viability. Long-term records of these processes can promote an improved understanding of their timing, amplitude, and environmental impacts. Here we present a sedimentary record from Lake Jian in Yunnan Province, southwestern China, which shows that land-use changes affected the lake watershed by at least 1200 CE, and that the intensity of soil erosion increased from 1450 CE onwards, as evidenced by increases in magnetic susceptibility and high concentrations of trace metals. The timing of the increase in atmospheric lead (Pb) transport, which was possibly related to the growth of metallurgical activity in the region, occurred ~250 years earlier than the anthropogenic soil erosion. Pb emissions resulting from the mining and smelting industry, coal burning, and the use of leaded gasoline led to enhanced Pb pollution in the area since the 1950s CE. Comparison of the results with geochemical records from lakes in northwestern Yunnan reveals that environmental disturbances were relatively limited during the intervals of the Nanzhao and Dali Kingdoms. However, enhanced human disturbances of lake watersheds in Yunnan occurred from the Yuan dynasty onwards, as a result of population increases caused by immigration to the area, which was followed by the changes in the type and intensity of human activity, with an enhanced anthropogenic impact after the middle twentieth century. Overall, our study provides a case study for understanding the historical background of the Anthropocene.
•A 15,000-year moisture/rainfall record for the western Chinese Loess Plateau.•Two independent dating methods were used.•Holocene east-west asymmetry in precipitation in the Chinese Loess ...Plateau.•Westward extension of the western Pacific subtropical high affected precipitation.
As the cradle of Chinese civilization the Chinese Loess Plateau (CLP) and its climatic and environmental history have attracted much research attention; however, the spatial characteristics of Holocene climatic conditions across the CLP remains unclear. We investigated five loess sections from the Ganjia Basin in the western CLP, and used paleoclimatic indexes from one well-dated loess-paleosol sequence to reconstruct precipitation variation during the past ~15,000 years. The chronology of the loess section is well established, based on 12 AMS 14C dates from bulk organic matter. Loess deposited before 8 ka (1 ka = 1000 years before 1950 CE) indicates that precipitation was low from ~15 to 8 ka. Subsequently, a paleosol, characterized by higher magnetic susceptibility and more negative organic carbon isotopic values, developed under the moist conditions of the middle to late Holocene. Comparison with paleoclimatic records from the CLP revealed that precipitation across the CLP was low during the early Holocene and reached its highest level during 8–3 ka, against the background of an enhanced East Asian summer monsoon (EASM). In the eastern CLP (the region east of the Liupan Mountains), the climate became dry after 3 ka because of a weakening of the EASM; however, precipitation in the western CLP was relatively high at this time. This observation of an east–west asymmetry in precipitation in the CLP during the Holocene based on geological data is supported by numerical modeling results from PMIP3, which indicate that it could have been caused by the westward extension of the western Pacific subtropical high. Our findings provide an analog for the study of interglacials on a longer time-scale and they demonstrate that the pattern of moisture conditions between the eastern and western CLP may differ on sub-orbital timescales.
Aqueous batteries have garnered significant attention in recent years as a viable alternative to lithium‐ion batteries for energy storage, owing to their inherent safety, cost‐effectiveness, and ...environmental sustainability. This study offers a comprehensive review of recent advancements, persistent challenges, and the prospects of aqueous batteries, with a primary focus on energy density compensation of various battery engineering technologies. Additionally, cutting‐edge high‐energy aqueous battery designs are emphasized as a reference for future endeavors in the pursuit of high‐energy storage solutions. Finally, a dual‐compatibility battery configuration perspective aimed at concurrently optimizing cycle stability, redox potential, capacity utilization for both anode and cathode materials, as well as the selection of potential electrode candidates, is proposed with the ultimate goal of achieving cell‐level energy densities exceeding 400 Wh kg–1.
Aqueous batteries show promise for enhancing portable high‐energy devices by increasing specific capacity and battery voltage. Researchers have proposed a dual‐compatibility battery configuration to optimize redox potential and capacity utilization in both anode and cathode materials, aiming for high cell‐level energy density after evaluating current battery technology's impact on energy density.
The distribution of vegetation across glacial Sundaland and the underlying mechanisms have long been debated. We address this issue by comparing a compilation of vegetation reconstructions with ...climate simulations from the Community Earth System Model 2 (CESM2). A new n-alkane δ13C record derived from higher plants, covering the period from 21 to 5 cal ka BP in the southern South China Sea, is presented. This record, combined with previous pollen-based reconstructions, indicates that C3 forests dominated the outer-to-mid shelf regions of the northern Sundaland between the Last Glacial Maximum (LGM) and Heinrich Stadial 1, while open grasslands occupied the inner shelf region. A compilation of vegetation reconstructions shows a glacial contraction of lowland rainforests in longitudinal extent compared to the Holocene, especially in southern Sundaland. Furthermore, the previously proposed “savannah corridor” or “dry tropical forests” existed in the interior of Sundaland during the LGM, extending from the Malay Peninsula to the Lesser Sunda Islands. Modelling studies suggest that changes in the seasonality of precipitation, rather than mean annual rainfall, are more relevant to vegetation changes between the LGM and the Holocene. The glacial emergence of Sundaland caused an eastward shift of the ascending branch of the Walker Circulation and a substantial reduction in atmospheric convection activity over Southeast Asia, leading to a decrease in water availability during the dry season in both hemispheres. The enhanced water stress thus favors the expansion of open environments.
•Regional vegetation reconstructions are compared with hydroclimate simulations from the CESM2 model.•Glacial outer-middle continental shelf of northern Sundaland was covered by rainforests.•Savannah landscape or dry tropical forests occupied the glacial interior of Sundaland.•Enhanced dry-season water stress could account for glacial expansion of open environments.
Cycling aging is the one of the main reasons affecting the lifetime of lithium-ion batteries and the contribution of aluminum current collector corrosion to the ageing is not fully recognized. In ...general, aluminum is corrosion resistant to electrolyte since a non-permeable surface film of alumina is naturally formed. However, corrosion of aluminum current collector can still occur under certain conditions such as lithium bis(fluorosulfonyl)imide (LiFSI)-based electrolyte or high voltage. Herein, we investigates the corrosion of aluminum current collector in the electrolyte of 1.2 M LiFSI in ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed solvents. The electrochemical results shows that the corrosion current of aluminum is enhanced by cycling time and potential, which is correlated with the surface species and morphology. The formation of AlF
, which is induced by deep penetration of F
anions through surface passivation film, leads to internal volume change and the surface crack in the end. Our work will be inspiring for future development of high-energy-density and high-power-density lithium-ion batteries in which the LiFSI salt will be intensively used.
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