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The latest Coupled Model Intercomparison Project Phase 6 (CMIP6) proposes new shared pathways (SSPs) that incorporate socioeconomic development with more comprehensive and scientific experimental designs; however, few studies have been performed on the projection of future multibasin hydrological changes in China based on CMIP6 models. In this paper, we use the Equidistant Cumulative Distribution Function method (EDCDFm) to perform downscaling and bias correction in daily precipitation, daily maximum temperature, and daily minimum temperature for six CMIP6 models based on the historical gridded data from the high-resolution China Meteorological Forcing Dataset (CMFD). We use the bias-corrected precipitation, temperature, and daily mean wind speed to drive the variable infiltration capacity (VIC) hydrological model, and study the changes in multiyear average annual precipitation, annual evapotranspiration and total annual runoff depth relative to the historical baseline period (1985–2014) for the Chinese mainland, basins and grid scales in the 21st century future under the SSP2-4.5 and SSP5-8.5 scenarios. The study shows that the VIC model accurately simulates runoff in major Chinese basins; the model data accuracy improves substantially after downscaling bias correction; and the future multimodel-mean multiyear average annual precipitation, annual evapotranspiration, and total annual runoff depth for the Chinese mainland and each basin increase relative to the historical period in near future (2020–2049) and far future (2070–2099) under the SSP2-4.5 and SSP5-8.5 scenarios. The new CMIP6-based results of this paper can provide a strong reference for extreme event prevention, water resource utilization and management in China in the 21st century. [ABSTRACT FROM AUTHOR]

As the only natural satellite of the earth, the Moon has always been the first choice for human exploration of the solar system. China's lunar exploration project (Chang'e project) was launched in 2004. At present, it has created a perfect end to the three phases of "orbiting, landing and returning". A series of remarkable research achievements have been made on the basic issues of current lunar scientific research, such as the Earth-Moon space environment, lunar surface material, morphology, geological structure, lunar subsurface and internal structure, and the origin and evolution of the Moon, further deepening the human understanding of the Moon. This paper briefly reviews the development process of China's lunar exploration project, summarizes the main research results and scientific understanding, and finally prospects to the future development of China's lunar and planetary exploration. [ABSTRACT FROM AUTHOR]

Sulphate (SO42−) is a main component of PM2.5 in China. The chemical formation mechanisms of sulphate are complex, and many air quality models have been used to analyse these mechanisms. To improve the accuracy of Weather Research Forecast-Chemistry (WRF-Chem) on sulphate, an alternative method is proposed in this paper. Moreover, data assimilation is performed to adjust the chemical reaction rates of sulphate. Based on the original reactions, a new sulphate parameterisation scheme, which includes two hypothetical reactions and six undetermined parameters, was added. Based on the WRF-Chem/DART (Data Assistance Research Testbed) system, the near-ground concentrations of SO42−, SO2, NO2, O3 and particulate matter are assimilated to adjust the six parameters. After adjusting the parameters, the new scheme can effectively solve the underestimation of SO42− and overestimation of SO2. The simulation of SO42− improved as the mean bias changed from −13.1 µg m−3 to 3.5 µg m−3 while SO2 improved from 17.0 µg m−3 to 6.3 µg m−3. The temporal and spatial variation characteristics predicted by the new scheme are consistent with the theoretical research results, indicating that the complex mechanism of sulphate formation could be replaced by the temporal and spatial variation characteristics predicted by the new scheme and that the parameters can be adjusted by data assimilation. Furthermore, the reaction rates of the SO42− parameterisation scheme of the WRF-Chem model are improved in this study, and a new method for improving the accuracy of the air quality model is provided. [ABSTRACT FROM AUTHOR]

The Sichuan-Yunnan area is located at the southeastern margin of the Tibetan Plateau, where tectonic movement is strong with deep and large faults distributed in a staggered manner, which results in strong seismic activities and severe earthquake hazards. Since the 21st century, several earthquakes of magnitude 7.0 or above occurred in this region, which have caused huge casualties and economic losses, especially the 2008 Ms8.0 Wenchuan earthquake. At present, earthquake monitoring and source parameter inversion, strong earthquake hazard analysis and disaster assessment are still the focus of seismological researches in the Sichuan-Yunnan region. Regional high-precision 3D community velocity models are fundamental for these studies. In this paper, by assembling seismic observations at permanent seismic stations and several temporary dense seismic arrays in this region, we obtained about 7.06 million body wave travel time data (including absolute and differential travel times) using a newly developed artificial intelligence body wave arrival time picking method and about 100,000 Rayleigh wave phase velocity dispersion data in the period range of 5–50 s from ambient noise cross-correlation technique. Based on this abundant dataset, we obtained the three-dimensional high resolution Vp and Vs model in the crust and uppermost mantle of southwest (SW) China by adopting the joint body and surface wave travel time tomography method considering the topography effect starting from the first version of community velocity model in SW China (SWChinaCVM-1.0). Compared to SWChinaCVM-1.0, this newly determined velocity model has higher resolution and better data fitness. It is accepted by the China Seismic Experimental Site as the second version of the community velocity model in SW China (SWChinaCVM-2.0). The new model shows strong lateral heterogeneities in the shallow crust. Two disconnected low velocity zones are observed in the middle to lower crust, which is located in the Songpan-Ganzi block and the northern Chuandian block to the west of the Longmenshan-Lijiang-Xiaojinhe fault, and beneath the Xiaojiang fault zone, respectively. The inner zone of the Emeishan large igneous province (ELIP) exhibits a high velocity anomaly, which separates the two aforementioned low velocity anomalies. Low velocity anomaly is also shown beneath the Tengchong volcano. The velocity structures in the vicinity of the 2008 Ms8.0 Wenchuan earthquake, the 2013 Ms7.0 Lushan earthquake and the 2017 Ms7.0 Jiuzhaigou earthquake mainly show high Vp and Vs anomalies and the mainshocks are basically located at the transition zone between the high and low velocity anomalies. Along with the segmentation characteristics of seismic activity, we suggest that areas with significant changes in velocity structures, especially in active fault zones, might have a greater potential to generate moderate to strong earthquakes. [ABSTRACT FROM AUTHOR]

Devonian cutinitic liptobiolith is a special cuticle-rich coal formed during the early stage of land plant evolution. In China, this special coal has previously only been reported in the Yangtze area, with the Luquan Devonian cutinitic liptobiolith of Yunnan Province being the most well-known. Recently, this type of coal was first discovered in the Bulonggoer Sag, to the northwest of the Junggar Basin, NW Xinjiang. Its geological age is regarded as the Givetian period of the late Middle Devonian, which is equivalent to the age of the Luquan Devonian coal. The cutinitic liptobiolith from NW Xinjiang has a distinct sheet-like texture resembling a stack of paper or leaf sheets in appearance, and so it is commonly called "paper coal" or "leaf coal". Ribbon-like cutinite (thick-walled type) is the most abundant maceral in the coal (>60% and up to 80%, on a mineral-free basis), followed by ribbon-like collotelinite. The NW Xinjiang and Luquan cutinitic liptobioliths share similar maceral compositions; while their coal-forming plants and depositional conditions are distinct. The NW Xinjiang cutinitic liptobiolith was deposited in a regional fluvial or flood plain condition, with lycopsids as the dominant coal-forming plants. In contrast, the Luquan cutinitic liptobiolith formed in a coastal-lagoon environment, with primitive ferns as the predominant coal-forming plants, followed by lycopsids. The saturated fractions of the NW Xinjiang and Luquan liptobioliths are mainly composed of tetracyclic diterpanes. However, the tetracyclic diterpane compositions in the NW Xinjiang cutinitic liptobiolith are distinct from those in the Luquan Devonian coal: The former is dominated by atisanes and the latter is mainly composed of phyllocladanes. Different coal-forming plants may have contributed to the distinct tetracyclic diterpane compositions. [ABSTRACT FROM AUTHOR]

To achieve carbon peak targets, realize carbon neutrality vision, and tackle global climate change, China must improve the carbon emission performance at the city level. Based on the carbon emission performance of 191 prefecture-level cities in China from 1997 to 2017, this paper analyses the evolution characteristics of urban carbon emission performance from three aspects: the overall spatial and temporal evolution, the differences according to both region and city size, and the differences among clusters categorized by carbon emission performance at the city level. This paper also reveals the impact of the social and economic transition on China's carbon emission performance. The results show that: (1) The overall level of carbon emission performance of Chinese cities is low, and there is a downward trend during the study period. The differences in carbon emission performance among cities are convergent, but there is a wide gap between high and low values. (2) The carbon emission performance of cities in eastern coastal areas is higher than that in non-coastal areas cities. Large urban agglomerations and economically developed regions, such as provincial capitals, are the agglomeration areas of high urban carbon emission performance values. (3) The carbon emission performance level of cities with similar sizes will converge. At the same time, such changes will enhance the differences among carbon emission performances at the city level within the same region. (4) Cities that belong to high urban carbon emission performance clusters are mainly distributed in the eastern region. Such cities are classified into large cities, supercities, and megacities. Compared with low urban carbon emission performance clusters, cities in high urban carbon emission performance clusters show a higher proportion in the medium-high level and high level of carbon emission performance. Moreover, cities in high urban carbon emission performance clusters are more likely to improve theirurban carbon emission performance. (5) The economic agglomeration effect, industrial structure adjustment and carbon intensity reduction have a significant impact on improving urban carbon emission performance. Population agglomeration has an incremental effect, and the anticipated benefits of environmental regulation have yet to be fully realized. The impacts of different clusters and different regions are variable. Finally, this paper advances policy enlightenment according to its research findings. [ABSTRACT FROM AUTHOR]

The reconstruction of high-resolution chronologies for prehistoric cultures is a prerequisite for understanding the history of human evolution and its relationship with environmental change, and is valuable for exploring the trajectory of transcontinental cultural exchanges in prehistoric time. The Hexi Corridor of northwest China was one of the earliest centers for long-distance culture exchange in the prehistoric world. The timing and sequence of cultural changes in this area remains poorly understood resulting from the lack of radiometric age control. This paper presents a refined radiocarbon (14C) chronology to resolve the timing of human occupation and cultural evolution in the Hexi Corridor. Radiocarbon dating of crop remains, which have an annual life cycle, has the advantage of eliminating problems such as the carbon stored in 'old wood'. As a result, 14C dates from crop remains are used to test the validity of the 14C dates derived from charcoal, bone and plant remains. The resultant database of ages is modelled using the Bayesian approach. The updated chronology presented in this paper shows generally good agreement with the original dates used to constrain cultural evolution in the Hexi Corridor. However, the occupation of the corridor by the Shajing and Shanma Late Bronze Age-Early Iron Age cultures appears to have taken place ~300 years later than previously thought. On the basis of comparing this updated chronology of cultural evolution with palaeoclimatic and historical records, it is proposed that the collapse of the Shajing and Shanma cultures occurred as a result of geopolitical impact rather than climate change. [ABSTRACT FROM AUTHOR]

The Banquan Basin is a pull-apart basin with the largest scale and the most prominent structure due to dextral slip of the Tanlu Fault Zone (TLFZ) in late Cenozoic. The depositional history of the basin records the start time and evolution of the right-lateral strike-slip movement of the TLFZ. This paper studies the sedimentary and tectonic evolution of the Banquan Basin by seismic reflection exploration, borehole detection and cosmogenic nuclide chronology. We analyze the coupling relationship between the pull-apart basin and the strike-slip fault and discuss the start time and tectonic significance of the right-lateral strike-slip of the TLFZ. Our study indicates that the Banquan Basin has undergone three evolutionary stages: weak rifting during the pre-pull-apart period, strong extension during the syn-pull-apart period and subsidence during the post-pull-apart period. This implies that the TLFZ, which controls the evolution of the basin, experienced an evolutionary process of weak activity, intensified activity and migration of activity toward the central basin. The sedimentary filling of the basin has strong response to the episodic pull-apart and extension of the basin. Lying upon the basement of the basin, a thin layer of Miocene mudstone slowly accumulated due to local rifting before the strong pull-apart event. Along with the dextral slipping and pull-apart process, the basin was filled with alluvial fan facies, fluvial facies and floodplain facies strata from bottom to top. The latest tectonic movement of the TLFZ in the North China Block in late Cenozoic was dominated by episodic dextral strike-slip motion, and this deformation pattern started at 4.01±1.27 Ma. The latest tectonic deformation in North China since late Cenozoic was governed by eastward extrusion and tectonic orogenesis of the eastern margin of the Qinghai-Xizang Plateau since late Miocene. The eastward thrusting of the Liupanshan fault zone and sinistral shearing of the Qinling fault zone led to the anticlockwise rotation and pushing of secondary blocks in North China, resulting in a planar bookshelf faulting and rotation pattern. This unique deformation pattern transferred eastwards to the North China Plain at ∼ Ma and the process continues to the present time. This planar bookshelf rotation, accompanied with regional sinistral strike-slip movement of the ∼EW-trending boundary fault zones to the north and south of the North China Block and dextral strike-slip motion of the NNE-trending boundary faults between secondary blocks, is likely to be the long-range effect of the strong extrusion of the eastern margin of the Qinghai-Xizang Plateau. [ABSTRACT FROM AUTHOR]

The glacial trough is a common glacier erosion landscape, which plays an important role in the study of glacier erosion processes. In a sharp contrast with the developing river, which is generally meandering, the developing glacial trough is usually wide and straight. Is the straightness of the glacial trough just the special phenomenon of some areas or a universal feature? What controls the straightness of the glacial trough? Until now, these issues have not been studied yet. In this paper, we conduct systematic numerical models of the glacier erosion and simulate the erosion evolution process of the glacial trough. Numerical simulations show that: (1) while the meandering glacier is eroding deeper to form the U-shaped cross section, the glacier is eroding laterally. The erosion rate of the ice-facing slope is bigger than that of the back-slope. (2) The smaller (bigger) the slope is, the smaller (bigger) the glacier erosion intensity is. (3) The smaller (bigger) the ice discharge is, the smaller (bigger) the glacier erosion intensity is. In the glacier erosion process, the erosion rate of the ice-facing slope is always greater than that of the back-slope. Therefore, the glacial trough always develops into more straight form. This paper comes to the conclusion that the shape evolution of the glacial trough is controlled mainly by the erosion mechanism of the glacier. Thereby, the glacial trough prefers straight geometry. [ABSTRACT FROM AUTHOR]

China has planned and built several world-class cascade high dams in Jinsha River, Dadu River, Lancang River, and Yarlung Zangbo River. The complex geological conditions in the reservoir area and numerous large-scale landslide bodies make the potential disaster risk of overflowing and cascade dam failure caused by landslide-generated tsunami under increasing severe situations. However, the study on describing and predicting the complex dynamic processes of generation, propagation, overflowing, wave setup, and the interaction between tsunami and lakeshore has not been systematically carried out. Based on the high-order Boussinesq-type equations, the development of the dynamic system of tsunamis in lakes coupled with the landslide process is realized using the finite volume method in this paper. To verify the accuracy and reliability of the study, the Xiluodu Reservoir is selected as the object to simulate the potential landslide-generated tsunamis. The factors such as the generation and propagation of tsunamis, dam overflowing, and wave setup in the downstream river are quantitatively evaluated and analyzed. The constructed landslide with a total volume of 24×106 m3 generates a near-field wave amplitude of about 28 m. The maximum wave run-up height is about 95 m, the volume of the dam overflowing water up to 2.13×106 m3, and the maximum wave height above the dam crest presents an M-shaped distribution. This LGWs event raises the downstream water level by nearly 40 m. The results show that the risk of landslide-generated tsunamis in the reservoir area in China cannot be ignored. The developed Boussinesq-type equations coupled with the landslide dynamics can simulate the whole process of generation, propagation, runup, and estimating the overflowing water volume of the tsunamis in the lake, laying a foundation for the quantitative risk assessment of tsunamis in lakes of high cascade dams in China. [ABSTRACT FROM AUTHOR]

Coupled effects of railway vibration, rainfall, and drying-wetting cycles contribute to new types of loess disasters such as the collapse and vibration-induced settlement of the railway subgrade, loess mass disintegration, and slope sliding, during the large-scale construction and operation of high-speed or heavy-haul railways in China. This has significant consequences for railways that require millimetre-level deformation control, seriously threatening railway operation and people's lives. Therefore, for the first time, "five vibration-induced effects" on loess subjected to vibration, water immersion, and dry-wetting cycles are discussed including the vibration-induced acceleration of cracking, infiltration, disintegration, sliding, and subsidence. In this paper, the vibration-induced acceleration of infiltration is discussed mainly. The response of loess to locomotive vibration along railways was determined using field sampling and data processing. The dominant frequency of locomotive vibration are 18–22 Hz and the maximum amplitude is 0.4 mm. Tests regarding the vibration-induced acceleration of the permeability were conducted on intact loess using a newly developed vibration permeability apparatus. The results reveal that the vibration accelerates the water permeability and increases the water saturation of loess. The permeability coefficient of saturated loess under vibration is ∼1.5–20 times of that without vibration, reaching a maximum at a vibration frequency of 20 Hz. Vibration-induced infiltration tests were carried out on a loess column and the vibration-induced acceleration of water infiltration, wetting front evolution, and air outflow were analysed. The vibration-induced acceleration of infiltration strongly depends on the dry density, vibration frequency, and vibration amplitude. This pioneering work explores the mechnism of loess disasters triggered by locomotive vibration, rainfall, and drying-wetting cycles. [ABSTRACT FROM AUTHOR]

Based on the global reanalysis data of the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research, the surface meteorological observation data, sounding data and satellite observation data, this paper comprehensively analyzes the evolution process and formation mechanism of a persistent severe dense fog process occurred on February 15–17, 2015 in Yancheng, eastern China. Through the numerical simulation experiment of Weather Research and Forecast (WRF) model, we further analyze the impact of sea-land breeze on the formation and burst reinforcement of fog. Results show that the precipitation caused by the southwesterly airflow in front of the upper-level trough and the low-pressure inverted trough are conducive to the formation of early rain fog, while the nighttime clear radiance under the control of surface cold high and the infiltration of weak cold advection are conducive to the formation and development of later radiation-advection fog. The WRF model simulates the fog evolution process, which is basically consistent with the actual fog area, and the simulation results are credible to a certain extent. The simulation results show that the establishment of sea breeze has an advection cooling effect on the near surface layer, which is conducive to the formation and development of the inversion layer on the near surface, providing stable stratification conditions for the formation and burst reinforcement of fog. On one hand, the strengthening of sea breeze circulation can continuously transport water vapor to the study area. On the other, the occurrence of ultra-low level jet is favorable for the accumulation of low-level water vapor. At the same time, the inversion intensity further strengthens, which is in favor of the burst reinforcement and long-term maintenance of fog. [ABSTRACT FROM AUTHOR]

There are many types of atmospheric heat engines in land-air systems. The accurate definition, calculation and interpretation of the efficiency of atmospheric heat engines are key to understanding energy transfer and transformation of land-air systems. The atmosphere over the Qinghai-Tibet Plateau (QTP) in summer can be regarded as a positive heat engine. The study of the heat engine efficiency is helpful to better understand land-air interaction and thermal-dynamic processes on the QTP. It also provides a new perspective to explain the impact of the QTP on the climate of China, East Asia and even the world. In this paper, we used MOD08 and ERA5 reanalysis data to calculate the atmospheric heat engine efficiency, surface heat source and atmospheric heat source on the QTP in summer (May to September) from 2000 to 2020. The average atmospheric heat engine efficiency on the QTP in summer from 2000 to 2020 varies between 1.2% and 1.5%, which is less than 1.6%; the heat engine efficiency in summer is higher than that in June, July and August; the Qaidam Basin is the region with the highest atmospheric heat engine efficiency, followed by the western QTP. The mean surface heat source on the QTP in summer from 2000 to 2020 is 96.0 W m−2, the atmospheric heat source is 90.7 W m−2, and the release of precipitation condensation latent heat is the most important component of the atmospheric heat source on the QTP in summer. There is a strong and significant positive correlation between the atmospheric heat engine efficiency and the surface heat source on the QTP in summer. The precipitation con densation latent heat is the most important component of the atmospheric heat source in summer and can reflect the precipitation process. There is a strong and significant negative correlation between the atmospheric heat engine efficiency and the atmo spheric heat source on the QTP in summer. [ABSTRACT FROM AUTHOR]

Concurrent compound dry and hot events (CDHEs) amplified more damange on the ecosystems and human society than individual extremes. Under climate change, compound dry and hot events become more frequent on a global scale. This paper proposes a mathematical method to quantitatively attribute changes of CDHEs to changes of precipitation, change in temperature and change in the dependence between precipitation and temperature. The attribution is achieved by formulating the total differential equation of the return period of CDHEs among Meta-gaussian model. A case study of China is devised based on monthly precipitation and temperature data during the period from 1921 to 2020 for 80 major river basins. It is found that temperature is the main driving factor of increases in CDHEs for 49 major river basins in China, except for the upper and middle reaches of the Yangtze River. In West China, precipitation changes drove the increase in CDHEs in 18 river basins (23%), particularly in parts of North Xinjiang, Qinghai and Gansu. On the other hand, dependence between precipitation and temperature dominated changes of CDHEs in 13 river basins (16%) of China with other factors, including parts of South China, East China and Northwestern China. Furthermore, changes in both the mean and spread of precipitation and temperature can also contribute to changes in CDHEs. [ABSTRACT FROM AUTHOR]

Located on the southeast coast of China, Fujian is an important junction for the spread and migration of agriculture and populations from mainland Asia to Taiwan and the Island Southeast Asia. Research on the emergence of agriculture and its relationship with the regional environmental context is key to understanding the evolution of ancient human-land interactions in the coastal zone of China. This paper presents a detailed microfossil analysis of the Dapingding site, which is located in the lower reaches of the Min River on the southeast coast of China. We found a large number of phytoliths produced in rice stems and leaves from the cultural layers of this site, dated to 7,500 cal. a BP. In addition, we found rice husk impressions and rice phytoliths in the pottery sherds of these cultural layers. Among these phytoliths, rice bulliform phytoliths with ≥9 fish-scale patterns indicating the degree of rice domestication, accounted for 44%. This percentage is much higher than the established standard for wild rice bulliform phytoliths with fish-scale patterns, suggesting that rice cultivation had already occurred on the southeast coast of China approximately 7,500 years ago. Subsequently, the starting time of agricultural activity on the southeast coast of China was pushed from 5,000 to 7,500 years ago. Comparing the regional history of sea level and coastline changes in the early to mid-Holocene, we suggest that the emergence of early rice cultivation in Southeast China was associated with high sea levels in the mid-Holocene and the last transgression in the Fuzhou Basin. The 'Fuzhou Bay', formed by the retreating coastline and transgression driven by high sea levels, may have provided a sea channel for the southward movement of northern rice farmers. [ABSTRACT FROM AUTHOR]

Seismic Rock physics plays a bridge role between the rock moduli and physical properties of the hydrocarbon reservoirs. Prestack seismic inversion is an important method for the quantitative characterization of elasticity, physical properties, lithology and fluid properties of subsurface reservoirs. In this paper, a high order approximation of rock physics model for clastic rocks is established and one seismic AVO reflection equation characterized by the high order approximation (Jacobian and Hessian matrix) of rock moduli is derived. Besides, the contribution of porosity, shale content and fluid saturation to AVO reflectivity is analyzed. The feasibility of the proposed AVO equation is discussed in the direct estimation of rock physical properties. On the basis of this, one probabilistic AVO inversion based on differential evolution-Markov chain Monte Carlo stochastic model is proposed on the premise that the model parameters obey Gaussian mixture probability prior model. The stochastic model has both the global optimization characteristics of the differential evolution algorithm and the uncertainty analysis ability of Markov chain Monte Carlo model. Through the cross parallel of multiple Markov chains, multiple stochastic solutions of the model parameters can be obtained simultaneously, and the posterior probability density distribution of the model parameters can be simulated effectively. The posterior mean is treated as the optimal solution of the model to be inverted. Besides, the variance and confidence interval are utilized to evaluate the uncertainties of the estimated results, so as to realize the simultaneous estimation of reservoir elasticity, physical properties, discrete lithofacies and dry rock skeleton. The validity of the proposed approach is verified by theoretical tests and one real application case in eastern China. [ABSTRACT FROM AUTHOR]

This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification. The dynamic and static solutions of these equations can be applied to calculate quantitative relationships between the concentration ratio of precursors and secondary fine particles as well as the physical clearance power of the atmosphere, chemical reaction rate, and the scale of a contaminated area. The dynamic solution presented here therefore corresponds with a theoretical formula for calculating the overall rate constant for the oxidation reaction of reducing pollutants in the actual atmosphere based on their local concentrations and meteorological monitoring data. In addition, the static solution presented in this paper reveals the functional relationship between the concentration of secondary fine particles and precursor emission rate as well as atmospheric self-purification capacity. This result can be applied to determine the atmospheric environmental capacity of a precursor. Hourly records collected over the last 40 years from 378 weather stations in mainland China as well as the spatiotemporal distribution sequence of overall oxidation reaction rates from precursors show that when the reference concentration limit of secondary fine particles is 100 μmol m-3, the atmospheric environmental capacity of total precursors can be calculated as 24890×1010 mol yr-1. Thus, when the annual average concentration limit of given fine particles is 35 μg m-3 and the ratio of sulfate and nitrate to 30% and 20% of the total amount of fine particles, the capacities of SO2, NOx and NH3 are 1255, 1344, and 832 (1010g yr-1), respectively. The clearance density of precursors for different return periods across mainland China under above conditions are also provided in this study. [ABSTRACT FROM AUTHOR]

Climate and climate change have always been a research focus of atmospheric sciences. This paper summaries research efforts, achievements and international contributions of the Chinese scientific community on climate and climate change over the past 70 years. The review is based on papers published officially in national or international scientific journals, and is organized to cover six aspects: (1) general climate studies; (2) impact of the Qinghai-Tibetan Plateau; (3) impact of the East Asian monsoon; (4) influences of teleconnection oscillation and westerlies; (5) climate dynamics and development of climate models; and (6) climate change. It is, however, to be noted that the present review can not be considered as an exhaustive one, since there is a huge body of literature in the field. [ABSTRACT FROM AUTHOR]

Helium gas is a scarce but important strategic resource, which is usually associated with natural gas. Presently, only one extra-large helium-rich gas field has been found in China: the Hetianhe Gas Field in the Tarim Basin. This paper reports a new example, the Dongsheng Gas Field (DGF) in the Ordos Basin. In this study, 92 natural gas samples from the DGF were analyzed for helium content and isotope composition using isotope mass spectrometry. The natural gas samples were found to have an average helium content of 0.133%, with 65 (70.7%) of the samples having a helium content of 0.1% or more. Based on the proven natural gas reserves of the DGF, the proven geological helium reserves were calculated to be 1.96×108 m3, suggesting that it represents the first extra-large helium-rich natural gas reservoir to be hosted in tight sandstone in China. The 3He/4He ratios of 5 natural gas samples from the DGF are within the range of 3.03×10−8−3.44×10−8. Therefore, the helium in the gas field is thought to be of typical crustal origin and to have formed in the granitic basement that is rich in uranium and thorium. The accumulation of helium-rich natural gas was controlled by regional tectonic activities. Activity along the fault connecting the reservoir with the basement caused release of the helium gas, which entered the overlying strata along the fault and accumulated with conventional hydrocarbon gas. Based on the structural background and the distribution of helium source rocks in the Ordos Basin, the main helium source rocks with high exploration potential are located in deep strata within the north and middle parts of the basin. [ABSTRACT FROM AUTHOR]

Regional processes on land-water-air interface carbon (C) budget and balance that interconnect the land and sea are in fact C neutrality critical processes within the earth system. It is therefore essential to quantitatively analyze synergistic land-water-air interface C transport and C exchange processes to gain a deep understanding of the important role that terrestrial ecosystems play in "missing C sink". This paper systematically analyzes global land-water-air interface C migration processes as well as C budget changes and associated impact mechanisms. It also investigates the important role that these C budgets and C cycling processes play in inland water bodies, respective to C budgets at the land-water-air interface. Moreover, this study reveals the regulatory mechanisms of land-water-air interface C budgets and balances under a background of global climate change. It also quantitatively evaluates the status of China's regional land-sea-air interface C budgets as well as the C sequestration potential of its lake systems. Finally, this study concludes that the explicit quantification of anthropogenic activity impacts on land-water-air interface C transport and exchange processes is of great significance to global C balances and C neutrality. [ABSTRACT FROM AUTHOR]

The Middle Miocene Climate Transition (MMCT, ∼14 Ma) is the largest cooling event in the Cenozoic "Coolhouse", which significantly impacts the global chemical weathering pattern. In this paper, the responses of the MMCT global cooling event in the deep South China Sea were studied by clay mineral assemblages analysis of the oceanic red beds (ORB) at International Ocean Discovery Program (IODP) Expedition 368 Site U1502. The results show that the clay mineral assemblages of the ORB at Site U1502 are mainly composed of smectite (56–88%), illite (7–29%), and kaolinite (6–20%), without chlorite. The contents of these clay minerals and illite crystallinity show a four-stage variation pattern during early-middle Miocene (22.8−10.8 Ma). Smectite decreased from average 81% during 22.8–16.2 Ma and 16.2–14.4 Ma to average 67% during 13.8–10.8 Ma, with a rapid decrease of ∼14% during 14.4–13.8 Ma. On the contrary, illite and kaolinite increased rapidly by ∼8% and ∼6%, respectively, during 14.4–13.8 Ma. Illite crystallinity increased from average 0.18°Δ2θ during 22.8–16.2 Ma to average 0.19°Δ2θ during 16.2–14.4 Ma, and then decreased rapidly by ∼0.02°Δ2θ during 14.4–13.8 Ma. The provenance analysis of clay minerals shows that illite and kaolinite mainly originated from South China landmass due to physical erosion, while smectite mainly came from the Luzon arc as the product of chemical weathering. Therefore, smectite/illite ratio and illite crystallinity are used as proxies of chemical weathering intensity in the early-middle Miocene. High values of the ratio and the crystallinity represent the enhanced chemical weathering, whereas low values indicate the weakened chemical weathering or the strengthened physical erosion process. The smectite/illite ratio and illite crystallinity both decreased rapidly during 14.4–13.8 Ma, indicating the chemical weathering in the surrounding area of the South China Sea weakened rapidly, which we believe is the result of the MMCT event forcing. In addition, their values increased slightly during 16.2–14.4 Ma, which is in response to the relatively enhanced chemical weathering during the Middle Miocene Climate Optimum (MMCO). The variation pattern of clay mineral assemblages of the early-middle Miocene ORB in the South China Sea and its rapid transformation during the MMCT reveal that the Cenozoic cooling played a specific role in controlling the chemical weathering of the Earth's surface. [ABSTRACT FROM AUTHOR]

On May 22nd, 2021, an MS7.4 earthquake occurred near the Maduo county of the Qinghai Province, China, within the Bayan Har Block. Seismic activities have been intense in this block, thus whether the Maduo Earthquake will bring subsequent seismic hazards to its surrounding regions raises wide concerns. In this paper, we first calculated the Coulomb failure stress changes caused by the Maduo Earthquake on nearby faults, and estimated how much these faults are brought closer or further from their next failures based on their stressing rates. Next, we combined the Coulomb failure stress changes with the rate-state fictional law to estimate the seismicity rate in the study region in the next decade. A declustered catalogue before the Maduo Earthquake was adopted to calculate background seismicity rate, and rate-state parameters are constrained by fault slip rates. Our results show that the Maduo Earthquake increases stress accumulations in the northwestern portion of the Qingshuihe fault (0.02 MPa at maximum), the two ends of the Kunlun Mountain Pass-Jiangcuo fault (0.01 MPa at maximum), and the northwestern portion of the Maduo-Gande fault (on average ∼0.09 MPa), and seismicity rates are expected to increase near these faults. What is especially worth noting is the seismic hazard in the region extending from the eastern end of the Kunlun Mountain Pass-Jiangcuo fault to the Maqin-Maqu seismic gap on the Eastern Kunlun fault, which is calculated to have experienced a maximum stress increase of 0.67 MPa after the Maduo Earthquake. On the other hand, stress accumulations are reduced in the southern end of the Elashan fault, the Eastern Kunlun fault segment to the west of Maduo, and the northwestern portion of the Dari fault. Seismic hazards are expected to be low in these regions. For the study region as a whole, the probability of an M≥6 earthquake taking place in the next decade is estimated to be 59%, about twice the value calculated for the time period before the Maduo Earthquake. [ABSTRACT FROM AUTHOR]

The Qaidam Basin on the Qinghai-Tibet Plateau is well endowed with a variety of critical metals, such as Li and Rb. However, little is known about the distribution, source, and enrichment mechanisms of these elements. In this paper, we present results of systematic geochemical and H-O-B isotopic analyses of brines in the Tertiary and Quaternary sediments of the Qaidam basin. The results reveal that the paleobrines from oil-bearing anticlines at Dafengshan, Nanyishan, Youquanzi, Jiandingshan, and Jianshishan are significantly enriched in Li and Rb, whose contents are 81.1–128.9 mg L−1 and 4.5–29.2 mg L−1, respectively, reaching levels of economic significance. High Rb contents (up to 12.5 mg L−1) and well-endowment of Li also characterize the Dongtai, Xitai, Yiliping, and Senie salt lakes in the Qaidam Basin. The Tertiary paleobrine average in δD and δ18O at −40.7‰ and 2.84‰, respectively. The paleobrine with the highest Li and Rb has δD and δ18O values close to magmatic water. The δ11B values are lower than those of river water but close to those of geothermal fluids, suggesting that replenishment by deep magmatic hydrothermal fluid is most likely the key mechanism for the anomalous enrichment of these elements in the paleobrines, though evaporation and water-rock reactions have contributed to the critical metal mineralization. The anomalous enrichment of Li and Rb in modern salt lake brines is closely related to the input of volcanic geothermal water. The relatively high Li and Rb contents of intercrystalline brines in salt lakes of the western Qaidam Basin and the increase of Li and Rb contents with increasing depth were caused by upwelling of local paleobrines along the fault zones. [ABSTRACT FROM AUTHOR]

Grass carp (Ctenopharyngodon idella) is a cyprinid species, widely living in the freshwater on the plain area of East Asia. The fish has characteristic comb-like pharyngeal teeth, an adaptation to their typical vegetarian feeding habit. This paper deals with fossil pharyngeal teeth that related to grass carp, found from about 20 localities, ranging from the lower Oligocene to Holocene. Based on the morphology of the teeth, we established two new genera and species related to the genus Ctenopharyngodon (Dezaoia saintjaquensis, Eoctenopharyngodon liui) and two new species of Ctenopharyngodon (C. xiejiaensis and C. orientalis). The first recognized C. idella pharyngeal teeth were from the lower Pliocene of Yushe, Shanxi, and many others from 11 Pleistocene to Holocene localities. Judged from the materials and their occurrences, the grass carp may have originated from the western part of China during the early Oligocene. Throughout the Miocene, the grass-carp-like pharyngeal teeth were discovered from a vast area in China, indicating an appropriate atmosphere for the grass carp to develop, although the climate in the western part of China was possibly drier than that in the eastern part. From the beginning of the Pliocene, as the consequence of a considerable uplift of the Tibetan Plateau, the large rivers in East Asia finally formed, created favorable conditions for the Recent grass carp to thrive. Most teeth were collected in association with fossil mammals. Therefore, we are using the associated fossil mammals as the checking reference against which to test our interpretation of the surrounding environment of the water system in which the grass carp lived. [ABSTRACT FROM AUTHOR]

The evolution of the Changjiang Delta is obviously affected by current rapidly rising sea level and drastically declining river discharge, and it is also vital for the sustainable development of Shanghai and the Changjiang River Economic Belt, which represent China's economic development leader and major national strategic area, respectively. In this paper, the growth pattern of Jiuduansha Island, the largest uninhabited alluvial island in the Changjiang Estuary, is studied in terms of the change in elevation, position and area over the past 50 years through using satellite-derived instantaneous shoreline positions and high/low tide exposure areas based on 497 satellite images from 1974 to 2020; and the influencing factors and future development patterns are further discussed by comparison with other alluvial islands or sandbars in the estuary The results show that Jiuduansha Island has maintained a rapid or even accelerated area growth rate, although the sediment discharge of the Changjiang River has sharply decreased in recent decades This sustained growth is mainly attributed to the existence of the estuarine turbidity maximum zone, coarsening fluvial sediment, onshore sediment replenishment by tide, cone-like geomorphology of Jiuduansha Island, and siltation promotion effect of vegetation The growth rate of the low tide exposure area of Jiuduansha Island increased from 1.9 km2 a−1 in 1974–1990 to 3.0 km2 a−1 in 1990–2020, and the growth rate of the high tide exposure area reached as high as 3.7 km2 a−1 in 1994–2020. The implementation of the Deep-Water Channel Project has significantly affected the evolution of Jiuduansha Island, including shifting the heads of Shangsha and Zhongxiasha from severe retreat to rapid accretion, and promoting tidal flat progradation seaward of the Jiangyanansha and Zhongxiasha, but restricting the growth of the low tide exposure area of Jiuduansha Island. [ABSTRACT FROM AUTHOR]

The North China Craton is the oldest continental block, and has suffered from large-scale lithospheric thinning and destruction, which in turn led to gold deposits in northern China. The decratonic gold deposits in the North China Craton became the most important gold deposits in China, and geophysical methods are key means to detect and discover gold deposits there. In this paper, based on the geological and petrophysical characteristics of the North China Craton, the geological model of the decratonic gold deposits is transformed into a geophysical model. At present, two methods of geophysical exploration of decratonic gold deposits are in use: rapid and efficient exploration on the scale of the ore concentration area, and large depth exploration on the scale of the deposit area. In detail, the airborne electromagnetic, magnetic and gravity methods are used to detect the shallow (1,500 m) anomaly area on the scale of the ore concentration area. Through the ground-controlled source electromagnetic and ground magnetotelluric methods, explorations for targets at significant depth (5,000 m) are carried out in the mining area. Then, taking the Liaodong ore concentration area as an example, geophysical methods are used to discover two prospecting areas around the Jianshanzi Fault in the Qingchengzi ore concentration area, Baiyun-Xiaotongjiapuzi deep prospecting area, and Qingchengzi deep prospecting area. Next, three prospecting areas are delineated around the Jixingou Fault in the Wulong mining area, Wulong deep prospecting area, Weishagou deep prospecting area, and Chang'an deep prospecting area. The anomalies in the ore concentration area and mining area are revealed by means of three-dimensional exploration methods, thereby providing technical support for the exploration of metal minerals such as decratonic gold deposits. [ABSTRACT FROM AUTHOR]

The North China district has been subjected to significant research with regard to the ore-forming dynamics, processes, and quantitative forecasting of gold deposits; it accounts for the highest number of gold reserves and annual products in China. Based on the top-level design of geoscience theory and the method adopted by the National Key R & D Project (deep process and metallogenic mechanism of North China Craton (NCC) metallogenic system), this paper systematically collects and constructs the geoscience data (district, camp, and deposit scales) in four key gold districts of North China (Jiaojia-Sanshandao, Southern Zhaoping, Wulong, and Qingchengzi). The settings associated with the geological dynamics of gold deposits were quantitatively and synthetically analyzed, namely: NCC destruction, metallogenic events, genetic models, and exploration models. Three-dimensional (3D) and four-dimensional (4D) geological modeling was performed using the big data on the districts, while the district-scale 3D exploration criteria were integrated to construct a quantitative exploration model. Among them, FLAC3D modelling and the GeoCube software (version 3.0) were used to implement the numerical simulation of the 3D geological models and the constraints of the fluid saturation parameters of the Jiaojia fault to reconstruct the 4D fault structure models of the Jiaojia fault (with a depth of 5000 m). Using GeoCube3.0, multiple integration modules (general weights of evidence (WofE), Boost WofE, Fuzzy WofE, Logistic Regression, Information Entropy, and Random Forest) and exploration criteria were integrated, while the C-V fractal classification of A, B and C targets in four districts was carried out. The research results are summarized in the following four areas: (1) Four gold districts in the study area have more than three targets (the depth is 3000 m), and the class A, B and C targets exhibit a good spatial correlation with gold bodies that are controlled by mining engineering at depths greater than 1000 m. (2) The Boost WofE method was used to identify the target optimization in 3D spaces (at depths of 3000–5000 m) of the Jiaojia-Sanshandao, Southern Zhaoping, and Wulong districts. (3) The general WofE method is based on the Bayesian theory in 3D space and provides robust integration and target optimization that are suitable for the Jiaojia-Sanshandao and Southern Zhaoping districts in the Jiaodong area; it can also be applied to the Wulong district in the Liaodong area using a quantitative genetic model and an exploration model. Random forest is a multi-objective integration and target optimization method for 3D spaces, and it is suitable for the complex exploration model in the Qingchengzi district of the Liaodong area. The genetic model and exploration criteria associated with the exploration model of the Qingchengzi district were constrained by the common characteristics of the gold fault structure, magmatic rock emplacement in North China, and the strata fold and interlayer detachment structure. (4) Based on the gold reserves and the 3D block unit model of the Sanshandao gold deposit in the Jiaojia-Sanshandao district, the gold contents of the 3D block units in class A and B targets of the ore concentration were estimated to be 65.5% and 25.1%, respectively. The total Au resources of the optimized targets below a depth of 3000 m were 3908 t (including 1700 t reserves), and the total Au resources of the targets at depths from 3000 to 5000 m were 936 t. The study shows that the deep gold deposits in the four gold districts of North China exhibit a strong "transport-deposition" spatial correlation with potential targets. These "transport-deposition" spatial models represent the tectonic-magmatic-hydrothermal activities of the metallogenic system associated with the NCC destruction events and indicate the Au enrichment zones. [ABSTRACT FROM AUTHOR]

The predominant types of high-grade iron deposits in China include skarn, sedimentary metamorphic (banded iron-formation, BIF-type), continental/submarine volcanic-hosted and magmatic Fe-Ti-V oxide deposits. Based on a comprehensive review of current studies on these deposits, this paper suggests that the oxygen concentration in atmosphere played an important role for the formation of BIFs, whereas the tectonic setting and deep magmatic differentiation processes are more important for the other types. Notably, both high temperature and high pressure experiments and melt inclusion studies indicate that during the differentiation, high temperature magmas could develop iron-rich magma via liquid immiscibility but not pure oxide melt ("iron ore magma"). Fe-P melt could be generated directly by liquid immiscibility under hydrous and oxidized condition. The formation of high-grade iron deposits is mostly associated with the processes related to multiple stages of superimposition, e.g., desiliconization and iron enrichment, removal of impurity, and remobilization and re-precipitation of iron. According to the temporal evolution, the high-grade iron deposit could be divided into multi-episode superimposition type (temporally discontinuous mineralization) and multi-stage superimposition type (temporally continuous mineralization). The former is represented by the sedimentary metamorphic iron deposit, and the latter includes those related to magmatic-hydrothermal fluids (e.g., skarn, volcanic-hosted and magmatic types). [ABSTRACT FROM AUTHOR]

Many orogenic belts in the world exhibit accretionary and collisional orogenic phases to varying extents. How accretion evolves into collision of the Central Asian Orogenic Belt (CAOB), the largest Phanerozoic accretionary orogenic belt, is an intriguing question. In this paper, we present new U-Pb age, geochemical and isotopic data for Permian-Triassic granitoids from middle Inner Mongolia, Northern China in the southeastern CAOB, and delineate the magmatic transition from subduction to (soft) collision. The magmatic record of soft collision is identified and characterized by thickened lower crust-derived high Sr/Y granitoids with a sub-linear distribution along the Solonker suture zone. Granitoids from Early Permian to Late Permian became more enriched in whole-rock Nd and zircon Hf isotopic compositions (εNd(t) values from 2.4 to −19.5, εHf(t) values from 11.6 to −33.7), indicating increasing incorporation of old crust. The change in peak timing of magmatism from west (ca. 264 Ma) to east (ca. 251 Ma) along the Solonker suture zone implies "scissor-like" closure of the Paleo-Asian Ocean. Integrated with previous studies, a three-stage tectonic model from the Permian to Triassic by accretion leading to collision on the south-eastern margin of CAOB is proposed. (1) Early Permian (> ca. 285 Ma): Juvenile magmatism on an active continental margin with double-sided subduction of the Paleo-Asian Ocean; (2) Middle Permian to Middle Triassic (ca. 285–235 Ma): Magma source transition from juvenile to old crust induced by a tectonic switch from arc to "scissor-like" closure and subsequent intra-continental orogenic contraction; (3) Late Triassic (< ca. 235 Ma): A-type and alkaline magmatism in response to post-collisional extension. [ABSTRACT FROM AUTHOR]

The detailed lithospheric structure of South China is the basis for the understanding of tectonic processes of eastern China. Specifically, two essential issues in the study of lithospheric structure are the thermal and compositional structures, which are usually derived from either geophysical or geochemical observations. However, inversions from single geophysical or geochemical datasets have certain limitations, making it necessary to develop joint inversions of geophysical, geochemical and petrological datasets. In this paper, through thermodynamic simulation and probabilistic inversion, we inverted multiple datasets including topography, geoid height, surface heat flow and surface wave dispersion curves for the 3D lithospheric thermal and compositional structure of South China. The results reveal a thin (< 100 km) and flat LAB beneath the South China Fold System Block and the lower Yangtze Craton. Also, we found that the lithospheric mantle is primarily composed of saturated peridotite, indicating that the ancient refractory lithospheric mantle has been replaced by new materials. The dominant dynamic mechanism for lithospheric thinning in eastern South China may be the flat subduction of ancient Pacific slab, while thermal erosion may have also played a significant role. In contrast, the LAB depth beneath the Sichuan Basin is much thicker (> 200 km), suggesting that the thick and cold craton lithospheric roots are retained. There may exist a discontinuous interface beneath the Sichuan Basin, with the saturated lower layer thicker than the refractory upper layer. As a result, the lithospheric mantle of the Sichuan Basin and surrounding regions is mainly composed of saturated and transitional peridotite. [ABSTRACT FROM AUTHOR]

To make a reliable reconstruction of past climate from soil-surface modern pollen, it is necessary to reduce the sources of error. In this paper, pollen percentages of the sub-continental scale modern pollen-climate dataset from China and Mongolia (with 68% soil-surface samples) are homogenized at various spatial scales. A tailored calibration-set is then applied to lake sediment-surface pollen assemblages from north-central China to evaluate their predictive power. Results indicate that spatial homogenization of modern pollen percentages can increase the proportion of inertia explained by climatic variables in CCA and improve the model performance of leave-one-out cross-validation using WA-PLS. Soil-surface pollen assemblages can thus be employed into a calibration-set for reliable climate estimation and they perform better when the calibration-set has been locally homogenized. Small-scale (e.g., radii 2, 5, or 10 km) homogenization reduces the local noise in soil-surface pollen assemblages and improves the cross-validated performance, while broader scale homogenization (more than 20 km radius) blurs the pollen-climate relationship. Lake sediment-surface pollen assemblages from close to the shore could contain pollen grains transported by rivers or from the shore vegetation and thus fail to represent regional climate well like the assemblages from the central part and deep-water area of lake. [ABSTRACT FROM AUTHOR]

China-US trade holds great significance for the world's political and economic landscape. Since 2018, the US government has imposed additional tariffs on Chinese exports on the grounds of the US trade deficit with China. However, the transfer of pollutants embodied in trade and the differences in environmental costs between China and the US have not been widely recognized. In this study, we quantify the embodied carbon emissions (the "virtual" emissions associated with trade and consumption) in China-US trade by constructing a carbon dioxide emissions inventory and a multiregional input-output model. The study shows that the US benefits from a trade surplus of environmental costs by importing energy-intensive and pollution-intensive products from China, which increases China's environmental pollution and abatement costs. In 2017, 288 Mt CO2 emissions were associated with products produced in China but finally consumed in the US, and only 46 Mt CO2 were associated with the US products that were consumed in China. From this perspective, China-US trade results in a net transfer of 242 Mt CO2 per year from the US to China, accounting for approximately 5% of the total CO2 emissions in the US. More importantly, for Chinese products exported to the US, the carbon emissions embodied in one unit of economic value amount to 0.92 kg/$ (RMB: USD=6.8:1), but for US products exported to China, the carbon emissions embodied in one unit of economic value amount to 0.53 kg/$, which means China will incur environmental costs that are 74% higher than those of the US while enjoying the same economic benefits. This environmental trade deficit has burdened China with higher environmental costs thaneconomic benefits. To address this environmental trade deficit, China should actively promote further industrial upgrading and energy structure adjustment and increase investment in innovation and R&D, thereby increasing the value added per unit of export products and reducing the environmental cost of producing export products. [ABSTRACT FROM AUTHOR]

This paper presents a review on the impact of El Niño on the interannual variability of atmospheric circulations over East Asia and rainfall in China through the anomalous anticyclone over western North Pacific (WNPAC). It explains the formation mechanisms of the WNPAC and physical processes by which the WNPAC affects the rainfall in China. During the mature phase of El Niño, the convective cooling anomalies over western tropical Pacific caused by the weakened convections trigger up an atmospheric Rossby wave response, resulting in the generation of the WNPAC. The WNPAC can persist from the winter when the El Niño is in its peak to subsequent summer, which is maintained by multiple factors including the sustained presence of convective cooling anomalies and the local air-sea interaction over western tropical Pacific, and the persistence of sea surface temperature anomalies (SSTA) in tropical Indian and tropical North Atlantic. The WNPAC can influence the atmospheric circulations over East Asia and rainfall in China not only simultaneously, but also in the subsequent summer after an El Niño year, leading to more rainfall over southern China. The current paper also points out that significant anomalies of atmospheric circulations over East Asia and rainfall over southern China occur in El Niño winter but not in La Niña winter, suggesting that El Niño and La Niña have an asymmetric effect. Other issues, including the impact of El Niño diversity and its impact as well as the relations of the factors affecting the persistence of the WNPAC with summer rainfall anomalies in China, are also discussed. At the end of this paper some issues calling for further investigation are discussed. [ABSTRACT FROM AUTHOR]

Models and observations are two fundamental methodological approaches in Earth system science (ESS). They evolve collaboratively and enhance one another. However, neither of these two approaches is perfect, and they have incompatibilities due to their methodological differences. The emergence of data assimilation (DA) has enabled these two approaches to develop in conjunction and form a harmonic ESS methodology. As a result, DA has shown a fresh vitality and applicability in ESS. This paper reviews the application of DA in the main branches of ESS, traces the coordinated evolution of DA with the methodologies of rationalism and empiricism, analyzes the relationships of DA with estimation theory and cybernetics, summarizes the advances of DA in China, and presents an outlook on the challenges facing the development of a uniform DA for ESS. DA theories and methods will continue to evolve and provide an increasingly mature methodology for enhancing the understanding and prediction of Earth as a system. [ABSTRACT FROM AUTHOR]

The Sichuan Basin is rich in shale oil and gas resources, with favorable geological conditions that the other shale reservoirs in China cannot match. Thus, the basin is an ideal option for fully "exploring petroleum inside source kitchen" with respect to onshore shale oil and gas in China. This paper analyzes the characteristics of shale oil and gas resources in the United States and China, and points out that maturity plays an important role in controlling shale oil and gas composition. US shale oil and gas exhibit high proportions of light hydrocarbon and wet gas, whereas Chinese marine and transitional shale gas is mainly dry gas and continental shale oil is generally heavy. A comprehensive geological study of shale oil and gas in the Sichuan Basin reveals findings with respect to the following three aspects. First, there are multiple sets of organic-rich shale reservoirs of three types in the basin, such as the Cambrian Qiongzhusi Formation and Ordovician Wufeng Formation-Silurian Longmaxi Formation marine shale, Permian Longtan Formation transitional shale, Triassic Xujiahe Formation lake-swamp shale, and Jurassic lacustrine shale. Marine shale gas enrichment is mainly controlled by four elements: Deep-water shelf facies, moderate thermal evolution, calcium-rich and silicon-rich rock association, and closed roof/floor. Second, the "sweet section" is generally characterized by high total organic carbon, high gas content, large porosity, high brittle minerals content, high formation pressure, and the presence of lamellation/bedding and natural microfractures. Moreover, the "sweet area" is generally characterized by very thick organic-rich shale, moderate thermal evolution, good preservation conditions, and shallow burial depth, which are exemplified by the shale oil and gas in the Wufeng-Longmaxi Formation, Longtan Formation, and Daanzhai Member of the Ziliujing Formation. Third, the marine, transitional, and continental shale oil and gas resources in the Sichuan Basin account for 50%, 25%, and 30% of the respective types of shale oil and gas geological resources in China, with great potential to become the cradle of the shale oil and gas industrial revolution in China. Following the "Conventional Daqing-Oil" (i.e., the Daqing oilfield in the Songliao Basin) and the "Western Daqing-Oil & Gas" (i.e., the Changqing oilfield in the Ordos Basin), the Southwest oil and gas field in the Sichuan Basin is expected to be built into a "Sichuan-Chongqing Daqing-Gas" in China. [ABSTRACT FROM AUTHOR]

Urban expansion is a hot topic in land use/land cover change (LUCC) researches. In this paper, maximum entropy model and cellular automata (CA) model are coupled into a new CA model (Maxent-CA) for urban expansion. This model can help to obtain transition rules from single-period dataset. Moreover, it can be constructed and calibrated easily with several steps. Firstly, Maxent-CA model was built by using remote sensing data of China in 2000 (basic data) and spatial variables (such as population density and Euclidean distance to cities). Secondly, the proposed model was calibrated by analyzing training samples, neighborhood structure and spatial scale. Finally, this model was verified by comparing logistic regression CA model and their simulation results. Experiments showed that suitable sampling ratio (sampling ratio equals the proportion of urban land in the whole region) and von Neumann neighborhood structure will help to yield better results. Spatial structure of simulation results becomes simple as spatial resolution decreases. Besides, simulation accuracy is significantly affected by spatial resolution. Compared to simulation results of logistic regression CA model, Maxent-CA model can avoid clusters phenomenon and obtain better results matching actual situation. It is found that the proposed model performs well in simulating urban expansion of China. It will be helpful for simulating even larger study area in the background of global environment changes. [ABSTRACT FROM AUTHOR]

It is well known that the destruction of the North China Carton (NCC) is closely related to subduction of the Paleo-Pacific slab, but materials recording such subduction has not been identified at the peak time of decratonization. This paper presents data of whole-rock major and trace elements and Sr-Nd-Hf isotopes and zircon U-Pb ages and Hf-O isotopes for Mesozoic volcanic rocks from the Liaodong-Jinan region in the northeastern NCC, in order to trace the subduction-related materials in their source and origin. The Mesozoic volcanic rocks in the Liaodong-Jinan region are mainly composed of two series of rocks, including alkaline basaltic trachyandesite, trachyandesite and trachyte, and subalkaline trachyandesite and andesite. Zircon U-Pb dating yields eruption ages of 129–124 Ma for these rocks. The Early Cretaceous volcanic rocks are all enriched in LILEs (such as Rb, Sr, Ba and Th) and LREEs, depleted in HFSEs (such as Nb, Ta and Ti), indicating that they were originated from mantle sources that had been modified by subducted crustal materials. However, they have relatively heterogeneous and variable isotopic compositions. The alkaline basaltic trachyandesite, trachyandesite and trachyte have enriched whole-rock Sr-Nd-Hf and zircon Hf isotopic compositions and mantle-like δ18O values, suggesting that they were derived from low-degree partial melting of an isotopically enriched lithospheric mantle source. In contrast, the subalkaline trachyandesite and andesite have relatively depleted isotopic compositions with zircon εHf(t) values up to +5.2 and heavy zircon O isotopic compositions with δ18O values of +8.1‰ to +9.09‰, indicating that they were originated from a lithospheric mantle source that had been metasomatized by melts/fluids derived from the recycled low-T altered oceanic basalt. All of these geochemical features suggest that the Early Cretaceous volcanic rocks in the Liaodong-Jinan region would result from mixing of mafic magmas with different compositions. Such magmas were originated from the enriched lithospheric mantle and the young metasomatized mantle, respectively, with variable extents of enrichment and depletion in trace elements, radiogenic isotopes and O isotopes. Importantly, the identification of the low-T altered oceanic crust component in the origin of Early Cretaceous volcanic rocks by the zircon Hf-O isotopes provides affirmative isotopic evidence and direct material records for Mesozoic subduction of the Paleo-Pacific slab that induced decratonization of the North China Craton. [ABSTRACT FROM AUTHOR]

As one of the largest Phanerozoic orogens in the world, the Central Asian Orogenic Belt (CAOB) is a natural laboratory for studies of continental dynamics and metallogenesis. This paper summarizes the research progresses of the accretionary processes and metallogenesis of the CAOB since the People's Republic of China was founded, and puts forward the prospect for future research. During the early period (1950s–1970s), several geological theories were applied to explain the geological evolution of Central Asia. In the early period of China's reform and opening-up, the plate tectonics theory was applied to explain the evolution of the northern Xinjiang and Xingmeng regions, and the opinion of subduction-collision between Siberian, Kazakhstan, and China-North Korea-Tarim plates was proposed. The idea of the Solonker-Yanbian suture zone was established. In the 1990s, the study of the CAOB entered a period of rapid development. One school of scholars including geologists from the former Soviet Union proposed a multi-block collision model for the assemblage of the CAOB. In contrast, another school of scholars, led by a Turkish geologist, Celal Şengör, proposed that the Altaids was formed through the growth and strike-slip duplicates of a single island arc, and pointed out that the Altaids is a special type of collisional orogen. During this period, Chinese geologists carried out a lot of pioneering researches on ophiolites and high-pressure metamorphic rocks in northern China, and confirmed the main suture zones accordingly. In 1999, the concept of "Central Asian metallogenic domain" was proposed, and it became one of the three major metallogenic domains in the world. Since the 21st century, given the importance for understanding continental accretion and metallogenic mechanism, the CAOB has become the international academic forefront. China has laid out a series of scientific research projects in Central Asia. A large number of important scientific research achievements have been spawned, including the tectonic attribution of micro-continents, timing and tectonic settings of ophiolites, magmatic arcs, identification and anatomy of accretionary wedges, regional metamorphism-deformation, (ultra)high-pressure metamorphism, ridge subduction, plume-plate interaction, archipelagic paleogeography and spatio-temporal framework of multiple accretionary orogeny, continental growth, accretionary metallogenesis, structural superposition and transformation, etc. These achievements have made important international influences. There still exist the following aspects that need further study: (1) Early evolution history and subduction initiation of the Paleo-Asian Ocean; (2) The accretionary mechanism of the extroversion Paleo-Asian Ocean; (3) The properties of the mantle of the Paleo-Asian Ocean and their spatiotemporal distribution; (4) The interaction between the Paleo-Asian Ocean and the Tethys Ocean; (5) Phanerozoic continental growth mechanism and its global comparison; (6) Accretionary metallogenic mechanism of the Central Asian metallogenic domain; and (7) Continental transformation mechanism. [ABSTRACT FROM AUTHOR]

Because typhoons are one of the most major natural disasters in the southeastern coastal areas of China, great attention has been paid to the prevention and mitigation of the disasters caused by typhoons. Over the past century, significant progress has been made in typhoon-related scientific research and operational work in China, including the construction of a network of typhoon monitoring stations, the establishment of forecasting operation systems, early warning and prevention of typhoon-related disasters, and the research of basic theories of typhoon behaviors and key forecasting technologies. This paper briefly reviews the milestones in the development history of typhoon research in China over the past century and a half in order to commemorate the predecessors, especially those who made historical contributions to the advancement of typhoon research since the economic and cultural reforms known as the "Opening of China", who provided historical references which enabled China to become an international leader in the field of typhoon science and technology. [ABSTRACT FROM AUTHOR]

Spatiotemporal patterns of column-averaged dry air mole fraction of CO2 (XCO2) have not been well characterized on a regional scale due to limitations in data availability and precision. This paper addresses these issues by examining such patterns in China using the long-term mapping XCO2 dataset (2009–2016) derived from the Greenhouse gases Observing SATellite (GOSAT). XCO2 simulations are also constructed using the high-resolution nested-grid GEOS-Chem model. The following results are found: Firstly, the correlation coefficient between the anthropogenic emissions and XCO2 spatial distribution is nearly zero in summer but up to 0.32 in autumn. Secondly, on average, XCO2 increases by 2.08 ppm every year from 2010 to 2015, with a sharp increase of 2.6 ppm in 2013. Lastly, in the analysis of three typical regions, the GOSAT XCO2 time series is in better agreement with the GEOS-Chem simulation of XCO2 in the Taklimakan Desert region (the least difference with bias 0.65±0.78 ppm), compared with the northern urban agglomeration region (−1.3±1.2 ppm) and the northeastern forest region (−1.4±1.4 ppm). The results are likely attributable to uncertainty in both the satellite-retrieved XCO2 data and the model simulation data. [ABSTRACT FROM AUTHOR]

Hominin-animal interactions at Pleistocene archaeological sites have been the main subject of research during human evolution. However, in contrast to that of ungulates, little is known about the evidence of human processing of carnivore species in this time interval of China. In this paper, we present the first case report of an interactive relationship between carnivore species and hunter-gathers in Pleistocene China, based mainly on a detailed taphonomic study of the faunal remains from Shuidonggou Locality 7. It seems highly probable that hominins butchered some individuals of carnivores and roasted bone elements with adhering meat at the site; whereas it's equally feasible that these animals were exploited by hominins mainly for their pelt or fur. In either way, evidence from the site indicates novel strategies in adaptive behaviors adopted by Late Pleistocene foragers in harsh environments of Northwest China. [ABSTRACT FROM AUTHOR]

Since the founding of the People's Republic of China 70 years ago, the subject of atmospheric physics and atmospheric environment has developed rapidly in China, providing important support for the development of atmospheric science and guarantee for the development of national economy. In this paper, the general advancement of atmospheric physics and atmospheric environment in last 70 years was described. The main research progress of atmospheric physics and atmospheric environment in the past 40 years of reform and opening-up was reviewed, the outstanding research achievements since the 21st century were summarized, the major problems and challenges are pointed out, and the key directions and suggestions for future development are put forward. [ABSTRACT FROM AUTHOR]

Synoptic meteorology is a branch of meteorology that uses synoptic weather observations and charts for the diagnosis, study, and forecasting of weather. Weather refers to the specific state of the atmosphere near the Earth's surface during a short period of time. The spatial distribution of meteorological elements in the atmosphere can be represented by a variety of transient weather phenomena, which are caused by weather systems of different spatial and temporal scales. Weather is closely related to people's life, and its development and evolution have always been the focus of atmospheric scientific research and operation. The development of synoptic meteorology is closely related to the development of observation systems, dynamical theories and numerical models. In China, observation networks have been built since the early 1950s. Up to now, a comprehensive meteorological observation system based on ground, air and space has been established. In particular, the development of a new generation of dense radar networks, the development of the Fengyun satellite series and the implementation of a series of large field experiments have brought our understanding of weather from large-scale environment to thermal dynamics, cloud microphysical structure and evolution characteristics of meso and micro-scale weather systems. The development of observation has also promoted the development of theory, numerical model and simulation. In the early days, China mainly used foreign numerical models. Lately, China has developed numerical model systems with independent intellectual property rights. Based on the results of high-resolution numerical simulations, in-depth understanding of the initiation and evolution mechanism and predictability of weather at different scales has been obtained. Synoptic meteorology has gradually changed from an initially independent development to a multidisciplinary approach, and the interaction between weather and the change of climate and environment has become a hot and frontier topic in atmospheric science. This paper reviews the important scientific and technological achievements made in China over the past 70 years in the fields of synoptic meteorology based on the literatures in China and abroad, from six aspects respectively including atmospheric dynamics, synoptic-scale weather, typhoon and tropical weather, severe convective weather, numerical weather prediction and data assimilation, weather and climate, atmospheric physics and atmospheric environment. [ABSTRACT FROM AUTHOR]

In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some weak areas of the research to restore vegetation changes over the past 20,000 years on the basis of previous work. This paper gives the vegetation zoning maps of 18, 9 and 6 ka BP respectively in southern China, and describes the distribution characteristics of plants in different zones/subzones. The results show that the vegetation zonations around 18 ka BP were significantly different from that at present. It appeared in turn with Cold-temperate coniferous forest and alpine meadow steppe zone, and Temperate mixed coniferous and broad-leaved forest zone/warm temperate deciduous broad-leaved forest zone from northwest to southeast in the west, and Temperate mixed coniferous and broad-leaved forest zone, Warm temperate deciduous broad-leaved forest zone, and Northern subtropical mixed evergreen and deciduous broad-leaved forest zone from north to south in the central and east. The vegetation distribution around 9 ka BP changed distinctively. Except that the northwest part was located in Mountain temperate mixed coniferous and broad-leaved forest zone, the vegetation in other areas occurred in turn with North subtropical mixed evergreen and deciduous broad-leaved forest subzone, Mid-subtropical typical evergreen broad-leaved forest subzone, and South sub-tropical monsoon evergreen broad-leaved forest subzone/Tropical seasonal rainforest and rainforest zone from north to south. There was little change in the appearance of vegetation zonations between 6 and 9 ka BP, but the northern edge of each vegetation belt moved a little northward, reflecting that the overall climate became warmer around 6 ka BP. The vegetation changes in southern China over the past 20,000 years were largely driven by environmental changes. Climate change was the main factor affecting the vegetation distribution. The impact of human activities became more and more remarkable in the later period. In the lower reaches of the Yangtze River and the delta region, sea level changes also influenced the vegetation distribution. [ABSTRACT FROM AUTHOR]

This paper presents the environmental history and its responses to palaeoclimatic changes since the start of the Holocene in the eastern portion of the desert belt (sand seas and sandy lands) in northern China by comparing the aeolian sandpalaeosol sequences and their palaeoclimatic proxies. The optically stimulated luminescence (OSL) ages of the aeolian sandpalaeosol sedimentary sequences and a series of palaeoenvironmental proxies show that: (1) The large-scale dune landscape currently in the Kubuqi Sand Sea was formed during the Holocene in general; and the palaeosol was generally developed during the period of 4–2 ka, indicating conditions favorable for vegetation growth, soil development, and organic carbon accumulation due to increased precipitation or effective moisture and weakened aeolian activities; the large-scale expansion of dunes in the recent 2 ka is closely linked to human activities. The variable discharge of the Yellow River with diversions for irrigation may have resulted in a more consistent supply of aeolian particles for dune field expansion. (2) The dune landscape of the Hunshandake Sandy Land was likely formed around 12 ka, and before this, the western part of the Hunshandake Sandy Land would have been covered by a single large lake; it was obviously wetter than today in the sandy land during the period of 9.6–3 ka and the palaeosols were developed at the same time. But the aeolian activities have not been completely dormant in this long-lasting wetter epoch; because the Holocene wetter period was likely time-transgressive across the region. (3) The palaeosol of the Hulunbuir Sandy Land began to develop as early as 14.5 ka, probably continuing until the last 2 ka. The palaeosol development of various dune fields in the eastern portion of the desert belt (sand seas and sandy lands) in northern China is spatially heterogeneous, and even the palaeosol development time in different locations within each sandy land is inconsistent. During the middle Holocene (especially the 7.5–3.5 ka), all the sandy lands were stabilized in general and the intensity of aeolian activities was significantly weakened. The number of palaeoenvironmental records in the eastern portion of the desert belt (sand seas and sandy lands) in northern China has increased rapidly in the past decade, but the amount of published data still does not match the vast extent of the dune fields. It does require much more in-depth palaeoenvironmental studies for a full understanding of the relationship between aeolian activities and climate change in northern China. [ABSTRACT FROM AUTHOR]

The stable carbon isotope composition (δ13C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the reconstruction of terrestrial ecosystems and global climate changes. It has also been widely used in paleolimnological studies in arid northwestern China. In recent years, however, an increasing number of studies have enriched the environmental significance reflected by the stable carbon isotope geochemistry of lakes; therefore, the interpretation of lake δ13C variations in paleoenvironmental reconstructions should be carefully evaluated from various aspects. In this paper, previous studies from the past several decades on the lacustrine δ13C variations in arid northwestern China were reviewed, and the possible mechanisms of the δ13C variations were discussed. Our study will provide a reference for the application of carbon isotope geochemistry in paleoenvironmental reconstructions. [ABSTRACT FROM AUTHOR]

A large number of primary oil and gas reservoirs have been discovered in Proterozoic strata all over the globe. Proterozoic sequences are widely distributed in China, and the discovery of large Sinian-aged gas reservoirs in the Sichuan Basin and Mesoproterozoic liquid oil seepages in North China shows that attention should be paid to the exploration potential of Proterozoic strata. In this paper, the main controlling factors of Proterozoic source rocks are discussed. Principally, active atmospheric circulation and astronomical cycles may have driven intense upwelling and runoff to provide nutrients; oxygenated oceanic surface waters could have provided suitable environments for the organisms to thrive; volcanic activity and terrestrial weathering caused by continental break-up would have injected large amounts of nutrients into the ocean, leading to persistent blooms of marine organisms; and extensive anoxic deep waters may have created ideal conditions for the preservation of organic matter. Additionally, the appearance of eukaryotes resulted in diversified hydrocarbon parent material, which effectively improved the generation potential for oil and gas. Through the comparison of Formations across different cratons, seven sets of Proterozoic organic-rich source rocks have been recognized in China, which mainly developed during interglacial periods and are also comparable worldwide. The Hongshuizhuang and Xiamaling Formations in North China have already been identified previously as Mesoproterozoic source rocks. The early Proterozoic Changchengian System is highly promising as a potential source rock in the Ordos Basin. In the Upper Yangtze area, the Neoproterozoic Datangpo and Doushantuo Formations are extensively distributed, and represent the major source rocks for Sinian gas reservoirs in the Sichuan Basin. Moreover, the Nanhuan System may contain abundant shales with high organic matter contents in the Tarim Basin, although this possibility still needs to be verified. Indeed, all three cratons may contain source rocks of Proterozoic strata; thus, these strata represent major exploration targets worthy of great attention. [ABSTRACT FROM AUTHOR]

The Changbaishan volcano is an active and considerably hazardous volcano located on the border of China and North Korea. This paper summarizes a series of geophysical surveys as well as seismological and volcano-observational networks around the Changbaishan volcanic area. We characterize deep structures related to the Changbaishan volcanic area. The prominent low-velocity anomalies and low-resistance bodies associated with the magma system under the Changbaishan volcano were detected in the crust and upper mantle, and high-velocity anomalies were imaged within the mantle transition zone, suggesting that the origin of the Changbaishan volcano is related to the subducted Pacific slab. However, there exist a few major obstacles for comprehensively elucidating the deep structure of the Changbaishan volcano as well as for the preparedness for and response toward future volcanic unrest and activity. It is essential to collect data from both China and Korean Peninsula to image the deep structure beneath the Changbaishan volcanic area. A multi-disciplinary approach comprising seismological investigations, deformation information from GNSS and InSar, and gravity and magnetotelluric surveying is a reliable manner for imaging high-resolution structures and fluid movement for the spatial distribution and variation of the volcanic magma chamber. An effective volcano-monitoring network system is considerably important to improve hazard assessments and characterize the potential future eruption of the Changbaishan volcano. [ABSTRACT FROM AUTHOR]

Scholars have long recognized the importance of organic artifacts to an improved understanding of the economic and social behavior of Palaeolithic hominins. However, in contrast to archaeological studies in other parts of the world, osseous industries from China have received only limited attention. As one of the first steps aiming at tipping this balance, the current paper examines, therefore, a shaped boar tusk—one particular element of hunter-gatherers' tool kit at Shuidonggou Locality 12 (SDG12). Morphological and metrical comparisons of the tusk with both paleontological specimens and bone artifacts from the same site demonstrate that wear pattern on one of the dentin surfaces of the tooth is not significant different from occlusal attritions in living animals, while linear striations on the other dentin facet are most probably artificial grinding marks formed by prehistoric toolmakers in attempts to manufacture a scraper. The tusk specimen from SDG12 represents the first evidence of a ground tooth in Upper Palaeolithic China. The current study indicates that hominins in Shuidonggou area had achieved a deepened understanding of physical properties of osseous material available in environs and ultimately broadened their range of raw material selection by adding a particular element to the inventory of subsistence tools. [ABSTRACT FROM AUTHOR]

Plate subduction is the most magnificent process in the Earth. Subduction zones are important sites for proceeding matter- and energy- transports between the Earth's surface and the interior, continental crust growth, and crust-mantle interactions. Besides, a number of geological processes in subduction zones are closely related to human beings' daily life, such as volcanic eruptions and earthquakes, formation of mineral deposits. Subduction process thus has long been the centric topic of Earth sciences. The finding in 1980s that continental crust could be subducted to mantle depths is a revolutionary progress in plate tectonic theory. Compared to oceanic crust, continental crust is colder, drier, lighter, and much more geochemically/isotopically heterogeneous Hence, continental subduction process would affect the structure, compositions and evolutions of the overlying mantle wedge even more. During continental subduction and subsequent exhumation, fluids and melts can be generated in the (de)hydration process and partial melting process, respectively. These melts/fluids play important roles in crust-mantle interactions, elemental migrations, isotopic fractionations, and mantle metasomatism. By summarizing recent research works on subduction zones in this paper, we present a review on the types, physicochemical conditions and compositions of fluids/melts, as well as the migration behaviors of fluid-related characteristic elements (Nb-Ta-V) and the fractionation behaviors of non-traditional stable isotopes (Li-Mg) in subduction zones. The aim of this paper is to provide the readers an update comprehensive overview of the melt/fluid activities in subduction zones and of Li-Mg isotope systematics in subduction-related rocks and minerals. [ABSTRACT FROM AUTHOR]