Search

The Qinling Orogenic Belt is a typical composite continental orogenic belt in China. The Qinling Mountains is not only a natural demarcation that separates China into a southern part and a northern part, in terms of Qinling Orogenic Belt's geography, climate, organisms, and river systems, but also forms a cultural boundary between the Yellow River Civilization to the north and the Yangtze River Civilization to the south. The Xi'an Qinling Zhongnanshan World Geopark is situated in the major portion of the collision zone between the South China and North China plates, which is also a typical section of the Qinling Orogenic Belt. It has been the focus of great attention for its long history of geological evolution, intensive tectonism, various rock types, unique strata, frequent magmatism, and abundant geological heritage sites. This paper clarifies the regional geological background of the Qinling Zhongnanshan World Geopark in 3 aspects, that is, the regional geological setting, regional evolution, and regional strata. With an integrated analysis and classification, the paper describes the main features of geological relics and geological remains of scientific significance in the geopark, on the basis of an investigation and systematic analysis for the geological relic resources of the world geopark. Compared with the geosites in other world geoparks, the sites in the Zhongnanshan area are particularly distinctive, even unique. [ABSTRACT FROM AUTHOR]

This paper highlights two aspects of the dynamic biogeochemical controls of riverine pCO2 in an increasingly impounded large subtropical river (the Yangtze): the terrestrial dominance through internal respiration of land-derived organic carbon and the influence of increased autotrophic activity in impounded areas on river pCO2. River pCO2 and total organic carbon (TOC) increase downstream on the main stem (pCO2: 528-1703 µatm; TOC: 137-263 µmol/L) and vary significantly among tributaries (464-3300 µatm; TOC: 109-340 µmol/L). pCO2 displays larger spatial variability than temporal variability and is spatially correlated with river organic carbon across the river ( p < 0.05-0.0001, seasonally independent). pCO2 is also negatively correlated with dissolved oxygen ( r2 = 0.46, p < 0.0001). Respiration of allochthonous organic carbon in water column is concluded as an essential source of CO2 supersaturation and river heterotrophy. However, significant benthic respiration and/or direct soil CO2 transport (e.g., via groundwater, ~80%) exist at the same time. The temporal and spatial distribution of POC compositional characteristics and chlorophyll a indicate the dominant control of terrestrial processes (e.g., organic matter transport and soil erosion) on the river pCO2 biogeochemistry, especially in warm seasons. Increased autotrophy and significant pCO2 decrease (>60%) do occur in impounded areas (especially in nutrient-rich rivers), but the decrease is mostly temporal and regional (~8% of the data points are significantly influenced, all from the upper reach and/or major tributaries). The paper concludes that terrestrial influence still dominates the pCO2 biogeochemistry in this increasingly intercepted and regulated river system. [ABSTRACT FROM AUTHOR]

The seasonality of internal tides is particularly conspicuous in shelf seas due to the dramatical variations in the marine environment. In this paper, the seasonal and spatial variabilities of M2 internal tides in the Yellow Sea (YS) are investigated using a high‐resolution numerical ocean model. The freshwater runoff of the Yangtze River is also considered. Because most nonlinear internal waves are of tidal origin, the simulated internal tides show good spatial consistency with the satellite‐detected nonlinear internal waves. During summer, the M2 internal tides are ubiquitous and originate from multiple generation sites (e.g., the west coast of the Korean Peninsula and the Yangtze River estuary). During other seasons, the spatial coverage of the internal tides becomes very limited. Multiple sources combined with seasonal onset and decay lead to complex seasonal interference patterns. The wavelengths vary both spatially and temporally, depending on the water depth and ocean stratification. Between spring and autumn, a seasonally reversed pattern of radiation of baroclinic energy flux is found in the southern YS, which may be induced by the seasonal variability of the YS Warm Current. Seasonal stratification controls the seasonality of the generation, propagation, and dissipation of internal tides and is maintained by the monsoon, seasonal circulation, and Yangtze River runoff. Our simulations suggest that, although internal tide dissipation is dispensable for the tidal energy budgets in the YS, internal tides seem to be the leading order contributor to the midcolumn diapycnal mixing, as they are more efficient mixers than barotropic tides. Plain Language Summary: Due to limited in situ observations and lack of attention, the basic characteristics of internal tides (especially the seasonal) in the Yellow Sea (YS) are still poorly understood. In this study, we have investigated the seasonal behaviors of the M2 internal tides in the YS by utilizing a numerical ocean model. The behaviors of the M2 internal tides vary significantly by season, which are very active during summer but are very weak during winter. The seasonal stratification in the YS is thought to be responsible for the seasonal behaviors of internal tides. We also found that the mixing induced by internal tide is nonnegligible in the summer shelf sea. Key Points: The M2 internal tides in the Yellow Sea are numerically simulated and show significant spatial and seasonal variabilityStratification has a crucial impact on the generation, propagation, and dissipation of internal tidesInternal tidal‐induced mixing and its seasonality are nonnegligible in the Yellow Sea [ABSTRACT FROM AUTHOR]

Abstract: Sediment transport in suspension can represent more than 90% of a river's total annual flux of sediment. In the case of the Yangtze River, more than 99% of the sediment supplied to the sea is suspended load. Suspended sediment is thus an important component of the total sediment load, with implications for channel dynamics, landscape evolution, ecology, and human‐related activities. For hydrological management of large basins such as the Yangtze River, knowledge of the processes governing suspended sediment concentration (SSC) is essential. An analysis of the temporal variation of SSC for the Upper Yangtze basin (defined at Pingshan station) is presented here. For this purpose, a database of 50 years of concurrent discharge and SSC measurements, made by the Yangtze River Commission, is used. The analysis is made using a novel probabilistic data‐driven technique, the Generalized Pareto Uncertainty (GPU). This technique allows for the testing of several strategies of prediction and forecast applied to a time series of SSC and streamflow. Changing between local or seasonal variables to feed these strategies, we inferred that although the main driver of the SSC transport is flow (as reported by previous authors), sediment storage is also a major control. Furthermore, the maximum necessary time lag for forecasts made with the data is on the order of one week, which provides one indication of the time scale of the local processes of SSC transport in the Upper Yangtze. In this paper, limitations and data requirements of the GPU methodology are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: In the western Yangtze Block, widespread Mesoproterozoic to Neoproterozoic rocks are the key to understanding the Precambrian tectonic‐magmatic evolution of the region. However, their petrogenesis and tectonic setting are still controversial. In this paper, zircon U‐Pb ages, Sm‐Nd isotopic and whole‐rock geochemical data are reported from selected fresh samples in the southern Dechang county, southwestern China, in order to constrain their emplacement age and magma source, as well as their petrogenesis and tectonic setting. They are mainly composed of biotite monzogranite, monzonitic granite, biotite granodiorites, and quartz diorite. Two ages of 1055 ± 43 Ma and 837.6 ± 3.8 Ma were obtained through zircon U‐Pb dating by LA‐ICP‐MS and LA‐MC‐ICP‐MS, respectively. According to their major element compositions, the Grenville‐age granites are peraluminous calc‐alkaline series calcic S‐type granite. In contrast, the mid‐Neoproterozoic granites are metaluminous calc‐alkaline series alkalic I‐type granite. Furthermore, the S‐type granites are enriched in LREEs relative to HREEs with (La/Yb)N ratios of 3.85–18.56 and underwent major fractionation with strongly negative Eu anomalies (Eu/Eu* = 0.38–0.66). In the MORB‐normalized trace element variation diagram, all the samples are enriched in Ce and large ion lithophile elements such as Rb, Th, and K, and depleted in high field strength elements such as Nb, and Ti, with negative Sr and Ti anomalies. The I‐type granites are enriched in LREEs with slight negative Eu anomalies (Eu/Eu* = 0.83–0.93). They are characterized by the enrichment of highly incompatible elements (such as K, Rb, Ba, Th) and LREEs, relative to MORB. Neodymium isotopic data show that the S‐type granites display 143Nd/144Nd values of 0.51241–0.51256, and have εNd (t = 1055 Ma) values of (−3.29) to (−3.81). Calculated tDM ages yield values from 1.87 to 1.91 Ga with the tDM.2stg ages of 1.86 to 1.9 Ga. The I‐type granites have 143Nd/144Nd ratios between 0.51192 and 0.51195, corresponding to initial εNd (t = 837 Ma) values of 1.22 to 5.63. Calculated tDM ages yield values from 1.0 to 1.38 Ga and the tDM.2stg ages yield values from 0.99 to 1.06 Ga. The S‐type granites are distinguished as syn‐collision granite, whereas the I‐type granites were formed as arc magmas according to the Rb‐(Yb+Ta) and R1‐R2 tectonic discrimination diagrams. To conclude, there are two types of spatially associated granite, the Mesoproterozoic S‐type granite which were derived from re‐melting of upper crustal mudstone and/or clastics and resulted from the convergence of two continental plates, and the mid‐Neoproterozoic I‐type granite which formed in continental arc and resulted from mantle‐derived magma mixed crust material, in the western Yangtze Block. Furthermore, we suggest that collision between the Yangtze and Cathaysia blocks occurred at about 1055 Ma, and caused the S‐type granite. The I‐type granite related to the subduction of oceanic lithosphere eastward underneath the Yangtze Block in the mid‐Neoproterozoic. [ABSTRACT FROM AUTHOR]

The widely developed black shales on the Yangtze Platform recorded palaeoceanographic environment information during the Ediacaran–Cambrian transition. This paper describes an integrated geochemical study of rare earth elements (REEs), redox‐sensitive trace elements (RSTEs), and total organic carbon (TOC) contents in Ediacaran–Cambrian black shales at Daotuo, northeastern Guizhou Province, South China. Integrated RSTE data from the Daotuo area, in combination with previously published Fe speciation and Mo‐based proxies from another six sections (Shatan, Jiulongwan, Zhongling, Yangjiaping, Longbizui and Wuhe), suggest three major periods of water euxinia during the Ediacaran–Cambrian transition. Under these conditions, organic matter and RSTEs experienced various levels of enrichment in the black shales, especially in the lower Jiumenchong Formation. Given the patterns of Mo‐U covariations, metal‐oxyhydroxide particulate shuttles may have operated during the black shale deposition of the Doushantuo Formation (Member II) at Daotuo. Conspicuously, the upper slope water was oxic‐dysoxic during the earliest Cambrian, as determined by the REE, RSTE data and sedimentological characteristics of the Liuchapo Formation and the basal Jiumenchong Formation. The generally low RSTE concentrations in the Bianmachong Formation black shales (Cambrian Series 2, end of Stage 3) suggest a persistently oxic water column in upper slope settings. The coincidence between the marine oxygenation and the development of the ecosystem likely indicates the galvanizing effects of enhanced oxygen and biological element content on the fauna during the Ediacaran–Cambrian transition. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To explore the public's risk perception and its causes and effects, it would be helpful to understand the basis for the public's disaster alleviation decisions and improve the effectiveness of risk communication. This paper analyses the relationship between the public's trust and risk perception by investigating the motives for trust building and the effects on public's flood risk perception in an area along the middle and lower reaches of Yangtze River. The objects of trust are disaster alleviation measures of monitoring and early warning, flood control projects, and disaster event management. The study data were obtained by conducting household interviews. The major conclusions are: (1) Public's trust in monitoring and early warning as well as in flood control projects is greater than the one in disaster event management. Trust has changed the public's assessment of flood risk and enhanced public confidence in disaster handling. Meanwhile, it reduces the propensity to adopt long-term preparation against disasters. Therefore, the public needs guidance in recognising the limits and validity of scientific and technological capabilities. (2) Public's trust is the product of not only individual psychological processes but also the external regional flood risk and social psychological characteristics. The levels of trust vary in different regions. Therefore, risk communication should be conducted according to regional characteristics. [ABSTRACT FROM AUTHOR]

Copyright of Island Arc is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Inner Lake, a typical waterfront lake located in the middle-lower reaches of the Yangtze River, is selected as the research area in this paper. Through field measurements and laboratory experiments, spatial distribution characteristics of the heavy metal cadmium (Cd) contents were revealed, and the release rate-flow disturbance curve in sediment of the Inner Lake was formed. The mathematical models of the migration and transformation of Cd were built and calibrated. With the models, the fluctuation characteristics of Cd pollution load were quantitatively assessed in different time scales, as in typical years (1998, 2001, and 2004) and in typical tidal cycles of dry seasons and flood seasons. The results showed that: there was a positive correlation between the release rate of Cd and flow disturbance intensity. Influenced by the hydrologic regime of the Yangtze River, the Cd pollution load was higher in high-water years than that in common-water years and low-water years, and was higher in flood seasons than that in dry seasons. Influenced by the tide of the Yangtze River, the Cd pollution load increased during ebb tide and reduced during the rising tide. [ABSTRACT FROM AUTHOR]

ABSTRACT The four main Chinese carps, collectively abbreviated as MCHA, include the black carp ( Mylopharyngodon piceus), grass carp ( Ctenop haryngodon idellus), silver carp ( Hypoph thal michthys molitrix), and the big-head carp ( Aristichyths nobilis). MCHA constitutes a significant catch of China's fresh water fishery. The construction of the Gezhouba and Three Gorges Dams greatly affects the physical habitat conditions of these four main carp species. This paper presents a time-series model for the assessment of instantaneous physical conditions in MCHA habitats. The model incorporates the effects of various hydrological variables (e.g. water level fluctuation, water temperature and sediment concentration) on MCHA habitat quality. The model is tested for the Yichang-Zhijiang reaches of the Yangtze River - a suitable region for analysing the effects of dam construction on the physical conditions of MCHA habitat. The model analyses instream ecological flow (IEF) characteristics of the study area in the spawning season of MCHA. On the basis of the analysis, the min, max and optimal IEFs are 6200, 51000 and 14 500 m3/s, respectively. The model introduces an efficient method for calculating the instantaneous habitat area on the basis of IEF and other physical conditions. If properly applied, the model is an efficient tool for assessing the effects of variations in flow conditions on MCHA habitat quality. The model could also be used in real time to analyse the combined effect of ecological regulations (e.g. as induced by the Three Gorges and Gezhouba Dams) on MCHA spawning conditions. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper discusses projections of heavy rainfall events in China during the 21st century based on daily precipitation data from the Fourth Assessment Report's (AR4) Coupled General Circulation Models (CGCM). Results show that all three experimental scenarios (scenarios A2, A1B, and B1) project consistent changes in frequency and intensity of heavy rainfall at the end of 21st century. In the regions of Northeast China and North China, there are no significant changes in frequency but there are remarkable increases in intensity of heavy rainfall, indicating that enhanced intensity is the main contributor to increased ratios of heavy rainfall to total annual precipitation in these regions. In regions of the lower reaches of Yangtze River and South China, increases in the amount of heavy rainfall are closely associated with increased frequency and increased intensity. Projected frequencies of heavy rainfall at the end of 21st century increase by 30.9 ∼ 56.6% in the Yangtze River and 35.9 ∼ 50.2% in South China compared to the period of 1980-1999, and projected intensities increase by 1.0 ∼ 5.7% and 2.8 ∼ 6.3%, respectively. Additionally, the ratios of heavy rainfall to total annual precipitation increase by 2.3 ∼ 5.4% in the Yangtze River and 1.8 ∼ 3.8% in South China. The significant increases of heavy rainfall ratios indicate that as the climate warms, heavy rainfall events are expected to increase at rates that are much faster than increases in total precipitation amounts, indicating that China will experience increased amounts of flooding. These results are substantially consistent among the three IPCC (Intergovernmental Panel on Climate Change) scenarios. The increased probability of heavy rainfall events in China is closely connected with increased transportation of water vapour from the Arabian Sea and the South China Sea. Additionally, atmosphere stratification has become increasingly unstable, which has provided a favorable background for the initiation of heavy rainfall at the end of the 21st century. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Solar radiation (Rs), a critical variable in agricultural and eco-environmental processes, is not measured at many meteorological stations. Prediction of Rs has drawn increasing attention in the recent years. However, due to the dynamic nature of atmosphere, accurate estimation of Rs from routinely measured meteorological variables is a challenging task. Studies have demonstrated that machine-learning approaches outperformed traditional statistical methods. This paper presents an application of Support Vector Machines (SVMs) for monthly mean daily Rs estimates using measured maximum, minimum, and mean air temperatures (Tmax, Tmin, and Tmean, respectively). Twenty-four stations covering different climatic regions-cold (C), severe cold (SC), mild (M), hot summer and cold winter within the Yangtze River Plain (HSCW-A), and hot summer and cold winter within the Sichuan Basin (HSCW-B)-across China were gathered and analysed. Five SVM models with different input attributes were created. These models were also compared with two empirical temperature-based methods. Root mean squared error (RMSE), Nash-Sutcliffe coefficient (NSE), and coefficient of residual mass (CRM) were employed to compare the performances of different methods. The newly developed model, SVM using Tmax-Tmin, and Tmean, outperformed other models with an averaged RMSE of 1.637 MJ m−2 and NSE of 0.813. On a regional scale, when Rs was estimated using the parameters developed at other sites, estimation of Rs within HSCW-B and SC regions were more reliable than in other zones. Especially in HSCW-B region, estimates of Rs using the parameters developed at Zunyi gave better performance (RMSE = 1.117 MJ m−2, NSE = 0.922) than that using the parameters obtained from their own data (RMSE = 1.309 MJ m−2, NSE = 0.894). The results showed that the SVM methodology may be a promising alternative to the traditional approach for predicting solar radiation at any locations where the records of air temperatures are available. Copyright © 2010 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

This paper examines the morphological development of the Yangtze River mouth, which has been diverting southeasterly (dextrally), according to historical (150 years) chart-based digital evolution model and on-site measured tidal flow data. We reveal a significantly narrowing of the northern river mouth branch from formerly >30 km wide to presently 10 km wide due to rapid siltation. Net siltation there, however, decreases gradually, which largely contrasts with the fact that the siltation has shifted to the southern river mouth area, as shown by many newly-emerged estuarine islands, sandy shoals and bifurcated branches. Our data have further demonstrated that the ebb flow that dominates in the study area changes its direction gradually from east to southeast from the inner to outer river mouth area, and its duration is much longer than the flood flow in the inner river mouth area, but nearly equal at the river mouth area. Accordingly, the sediment transport pathway has been diverted from east to southeast. We examine whether the Coriolis Force could explain the dextral diversion of the ebb flow and the altered morphodynamical processes. Although too weak to strengthen the tidal flows, the Coriolis Force can drag the ebb flow southeasterly, and so influence sediment transport paths at the estuarine scale. The Coriolis Force is limited in the inner river mouth, but substantial at and in the outer river mouth area when gradually free of estuarine topographic constraints. The Coriolis Force causes an offset in propagation of in-out flow directions at the river mouth area to form a slack water setting prone to estuarine siltation. Using the present approach also enables explanation of the morphological development of the Holocene Yangtze delta-coast that extends to the southeast. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we estimate the inputs of nitrogen (N) and exports of dissolved inorganic nitrogen (DIN) from the Changjiang River to the estuary for the period 1970-2003, by using the global NEWS-DIN model. Modeled DIN yields range from 260 kg N km-2 yr-1 in 1970 to 895 kg N km-2 yr-1 in 2003, with an increasing trend. The study demonstrated a varied contribution of different N inputs to river DIN yields during the period 1970-2003. Chemical fertilizer and manure together contributed about half of the river DIN yields, while atmospheric N deposition contributed an average of 21% of DIN yields in the period 1970-2003. Biological N fixation contributed 40% of DIN yields in 1970, but substantially decreased to 13% in 2003. Point sewage N input also showed a decreasing trend in contribution to DIN yields, with an average of 8% over the whole period. We also discuss possible future trajectories of DIN export based on the Global NEWS implementation of the Millennium Ecosystem Assessment scenarios. Our result indicates that anthropogenically enhanced N inputs dominate and will continue to dominate river DIN yields under changing human pressures in the basin. Therefore, nitrogen pollution is and will continue to be a great challenge to China. [ABSTRACT FROM AUTHOR]

In 2002, China launched the South-to-North Water Transfer Project after completing a 50-year feasibility study. By 2050, the three-route (i.e., East, Middle, and West) project will be capable of transferring 44.8 billion m3/year of water from the water rich Yangtze River to the arid north to alleviate water shortage and help secure a balanced social and economic development across the nation. However, diversion of such a large quantity of water could profoundly change the riverine environment of the upper Yellow River and the lower reach of the Han River, a tributary of the Yangtze River and the water supplying area of the project’s Middle Route, because of changes in the annual discharge. Secondary salinization seems inevitable in the water receiving areas of the North China Plain, and decrease in the discharge of the Yangtze River will result in seawater intrusion into the Yangtze Delta. This paper describes the project and discusses its environmental implications. Additionally, a long-term monitoring strategy under the umbrella of the Chinese Ecological Research Network is proposed for environmental monitoring. [ABSTRACT FROM AUTHOR]

The Eurocentric growth model has been the basic workhorse for numerous Chinese economic historians. This deep seated Eurocentric paradigm is concerned mainly with conterfactuals and tends to ignore past reality. To illustrate the problems of this Eurocentric approach, this paper examines the rural economy of Jiangnan, also known as the Yangzi Delta, during late imperial times. A main characteristic of the villages in the Wuxi county in Jiangnan were the mixture of the rural–urban lifestyle and development. Jiangnan's developmental patterns, in the Song and the Qing dynasty, from the Maoist period (pre-1979) to post-1979 development, contrast sharply with the predictions of the Western development models. [ABSTRACT FROM AUTHOR]

Container ports located in a delta of navigable waterways generally strive to develop the inland river services as a competitive transport mode, with a view to serving local and distant hinterland regions. The spatial and functional development of river-based container networks is location-specific and time-specific. While each barging network and associated seaport system has its own dynamics, similarities in development patterns cannot be excluded. This paper discusses similarities and dissimilarities between the spatial and the functional development of the container river service networks of the Yangtze River and the Rhine River. It is shown that the Yangtze service network has the tendency to converge, in more than one aspect, with the (historical) development pattern of inland container services in the Rhine basin. [ABSTRACT FROM AUTHOR]

Soil erosion in the upper reaches of the Yangtze River in China is a major concern and the Central Government has initiated the Grain-for-Green Programme to convert farmland to forests and grassland to improve the environment. This paper analyses the relationship between land use and soil erosion in Zhongjiang, a typical agricultural county of Sichuan Province located in areas with severe soil erosion in the upper reaches of the Yangtze River. In our analysis, we use the ArcGIS spatial analysis module with detailed land-use data as well as data on slope conditions and soil erosion. Our research shows that the most serious soil erosion is occurring on agricultural land with a slope of 10∼25 degrees. Both farmland and permanent crops are affected by soil erosion, with almost the same percentage of soil erosion for corresponding slope conditions. Farmland with soil erosion accounts for 86⋅2 percent of the total eroded agricultural land. In the farmland with soil erosion, 22⋅5 percent have a slope of <5 degrees, 20⋅3 per cent have a slope of 5∼10 degrees, and 57⋅1 percent have a slope of >10 degrees. On gentle slopes with less than 5 degrees inclination, some 6-percent of the farmland had strong (5000∼8000 t km-2y-1) or very strong (8000∼15000 t km-2y-1)erosion. However, on steep slopes of more than 25 degrees, strong or very strong erosion was reported for more than 42 per cent of the farmland. These numbers explain why the task of soil and water conservation should be focused on the prevention of soil erosion on farmland with steep or very steep slopes. A Feasibility Index is developed and integrated socio-economic assessment on the feasibility of improving sloping farmland in 56 townships and towns is carried out. Finally, to ensure the success of the Grain-for-Green Programme, countermeasures to improve sloping farmland and control soil erosion are proposed according to the values of the Feasibility Index in the townships and towns. These include: (1) to terrace sloping farmland on a large scale and to convert farmland with a slope of over 25 degrees to forests or grassland; (2) to develop ecological agriculture combined with improving the sloping farmland and constructing prime farmland and to pay more attention to improving the technology for irrigation and cultivation techniques; and (3) to carry out soil conservation on steep-sloping farmland using suggested techniques. In addition, improving ecosystems and the inhabited environment through yard and garden construction for households is also an effective way to prevent soil erosion. [ABSTRACT FROM AUTHOR]

This paper provides an evaluation of current arrangements made for compensation and resettlement to farmers who will be displaced by the construction of the Three Gorges Project (TGP) on the Yangtze River. Kaixian County is used as a case study. Under present regulations the specific value of peri–urban land is underestimated, neither cash–in–hand arrangements nor land–for–land swaps are adequate. There are other problems. The availability of suitable land for resettlement is scarce and rarely of equivalent quality. The inflexibility of the ‘household responsibility system’ contributes to the problem. It is suggested that some of those facing displacement should be encouraged to accept resettlement in places at considerable distance from their current homes and that a more creative approach should be taken to the issue of compensation to enable people to develop their trade and business skills. [ABSTRACT FROM AUTHOR]

In the East Asian monsoon region, eolian deposits widely distributed in the middle-lower reaches of the Yantgze River are among the best materials available for studies on Quaternary climate change in the subtropical zone of Southern China. Typical eolian deposits in this region include upper Xiashu Loess (XL) and underlying Vermiculated Red Soil (VRS) layers. In this paper, chronological and paleoclimatic studies are conducted on an eolian deposit sequence near Jiujiang (JJ) city in northern Jiangxi province. A magnetostratigraphic study, combined with optically stimulated luminescence (OSL) dating, is conducted on the JJ section and provides further evidence that eolian deposits in the middle-lower reaches of the Yangtze River have been formed since the late Early Pleistocene, and that the boundary age between the XL and VRS layers is about 300-400 kaBP. In grain-size records of the JJ section, the median grain-size and content of the >30 μm size fraction increase sharply after 300-400 kaBP, representing an East Asian winter monsoon intensification event. Further pollen analysis reveals differing pollen assemblages before and after 300-400 kaBP: there is an evident increase in plants adapted to grow in a warm humid environment after 300-400 kaBP, implying an increase in precipitation caused by intensification of the East Asian summer monsoon. Global ice volume and uplift of the Tibet Plateau (TP) are regarded as crucial factors influencing variations of the East Asian monsoon on a long-term scale. The deep-sea δ18O record, which reflects variations in global ice volume, shows no obvious change after 300-400 kaBP. Moreover, the influence of global ice volume changes on the East Asian summer and winter monsoons is inverse; the global ice volume increase (decrease) implies a strengthened (weakened) winter monsoon and weakened (strengthened) summer monsoon. We therefore interpret the coupled intensifications of the East Asian summer and winter monsoons at about 300-400 kaBP to the uplift of the TP in the Middle Pleistocene. This climate event is also documented in eolian deposits from the southern margin of the Chinese Loess Plateau (CLP) and from the desert-loess transitional belt. However, it is not recorded in the loess-paleosol sequences from the central part of the CLP, thereby indicating differing climate responses to TP uplift in different regions, which requires further study. [ABSTRACT FROM AUTHOR]

This study investigates the distributions of Br, Ca, Cl, Cr, Cu, K, Fe, Mn, Pb, Ti, V and Zn in Phragmites australis root system and the function of Fe nanoparticles in scavenging metals in the root epidermis using synchrotron X-ray microfluorescence, synchrotron transmission X-ray microscope measurement and synchrotron X-ray absorption near-edge structure techniques. The purpose of this study is to understand the mobility of metals in wetland plant root systems after their uptake from rhizosphere soils. Phragmites australis samples were collected in the Yangtze River intertidal zone in July 2013. The results indicate that Fe nanoparticles are present in the root epidermis and that other metals correlate significantly with Fe, suggesting that Fe nanoparticles play an important role in metal scavenging in the epidermis. [ABSTRACT FROM AUTHOR]

Ground‐level ozone (O3) and atmospheric fine particulate matter (PM2.5) pollution are the major challenges for continually improving air quality in the Yangtze River Delta (YRD) region of China. Understanding regional transport patterns of PM2.5 and O3 pollution is essential for the development of regional cooperative prevention strategies. This study shows the annual concentration of PM2.5 in the YRD decreased by 18.5% from 2015 to 2018, while the mean values of the daily maximum 8‐hr average (MDA8) O3 concentration from March to October increased by 16.3%. A complex network method is utilized to investigate the regional transport of PM2.5 and O3 in different grid cells (nodes). The source apportionment method within the chemistry transport model is applied to verify the reliability of the complex network method. Interregional and intraregional transport play an important role in both PM2.5 and O3 over the YRD. The northern part of the YRD contributes much more than other areas, while the central part of the YRD, especially the southern part of Jiangsu, is the largest contributor of O3 in the YRD in the summer, accounting for about 70%. Intraregional transport plays more of a major role in increasing PM2.5 pollution than O3 pollution. This study not only verifies the transport patterns of heavy pollution through the complex network method and traditional source apportionment technology, it also reveals that both methods provide great potential in understanding transport patterns and air pollution relationships, which are the solid foundation for emission mitigation in the YRD region. Key Points: Complex network method provides a foundation for an in‐depth analysis of regional transport with chemical transport model at grid levelThe results show that the Suxichang and Hangjiahu areas are the most prominent contributors of both PM2.5 and O3 in the Yangtze River Delta (YRD)The southern Huangshan and the border of Jinhua and Lishui are the major receptors for PM2.5 and O3 in the YRD [ABSTRACT FROM AUTHOR]

Four research cruises were carried out during March and July in 2015 and 2016 in the Changjiang (Yangtze) River Estuary and the adjacent shelf. Nutrient concentrations (regarded as static parameters) were measured in the surface and bottom waters collected at 86–99 stations over the course of these cruises. In addition, unfiltered seawater samples were incubated onboard for 48 hr to measure the potential change rates of nutrients (regarded as dynamic parameters). These parameters can help directly elucidate non‐conservative behaviors of nutrients in order to determine whether seawater serves as a source or a sink. Large nutrient sinks (with more negative variation rates) were consistently found at the surface during the two July cruises at the stations just along the outside edge of the turbidity maximum zone near the mouth of the river. Negative rates, although with much smaller magnitudes, were also found in most bottom water samples in July and at both the surface and bottom in March. The high net nutrient uptake rates at the surface in the summer triggered bloom events later at the seaward stations, showing that high net nutrient uptake is the cause and high chlorophyll‐a is the consequence of the bloom. Such information about biogeochemical cycling of nutrients and the mechanisms and development of bloom events occurring in large river estuarine and coastal areas could not have been obtained if these static and dynamic parameters had not been studied together. Plain Language Summary: In this study, we proved the ability of estuary as the "biogeochemical filter" in the large‐river dominated areas and directly elucidated nutrient non‐conservative behaviors. The concentration parameters (static parameters) revealed more about the instantaneous situations of nutrients, while the change rates (dynamic parameters) focused more on potential change trends of nutrients. Large nutrient sinks (with more negative variation rates) were consistently found at the surface during the summer at the stations just along the outside edge of the turbidity maxima zone. Our data indicated the high net nutrient variation rates at the surface in the summer triggered the bloom events later at the stations seaward away with distances of several tens of kilometers. Key Points: By introducing "dynamic" parameters, it can be more intuitive to observe that nutrients are more active in summerHigh nutrient variation rates and high chlorophyll‐a concentrations seldom occurred at the same timeA new approach was developed to elucidate the non‐conservative behavior of nutrients in large river estuaries [ABSTRACT FROM AUTHOR]

The maturation of marine phylogeography depends on integration of comparative information across different regions globally. The northwestern Pacific, characterized by unique tectonic setting, however, is still underrepresented. This study seeks to highlight its phylogeographical history based on the available population data, focusing on three seas: the East China Sea ( ECS), the South China Sea ( SCS) and the Sea of Japan ( SOJ). We first conducted a literature survey to evaluate current research efforts and then reanalysed the population structure, historical demography and genealogy for two selections of studies (namely 'the ECS category' and 'the multiple-sea category') to elucidate the evolutionary processes within and across the seas, respectively. For the ECS category, the meta-analyses revealed most studies displayed a shallow phylogeny, indicating a single origin from the sea. Significant population structure was commonplace, particularly in molluck and crustacean studies, with proportions of 89% and 80%, respectively. Nearly all studies selected showed signals of population expansion: the times estimated were closely linked to a period of ~120-140 Kya rather than the last glacial maximum. For the latter category, divergent intraspecific lineages appeared among seas and overlapped in the adjacent regions, a pattern implying each sea had served as an independent refugium during glaciations. The genetic splits, however, were estimated to arise from separate events dating from late Miocene to middle Pleistocene. As phylogeography is still in its infancy in the region, more effort is needed to test and complement the general rules abstracted here. Finally, challenges and prospects were discussed to accelerate further research. [ABSTRACT FROM AUTHOR]

Cenozoic surface uplift of Tibetan Plateau has driven the birth and reorganization of large river systems in Asia. The development of the Yangtze River, closely linked to plateau uplift, has important implications for the regional tectonic-geomorphology processes, but is still under debate. The key scientific question is whether the Upper Yangtze (upper Jinshajiang) once flowed southeast to the South China Sea. In this study, we carried out provenance analysis on Paleogene sedimentary rocks in the Jianchuan Basin, composed of the Baoxiangsi, Jinsichang, and Shuanghe formations. We compared them with similar deposits in other regional basins, as well as with potential sources. Heavy-mineral and geochemical data show that sediments from the Jinsichang formation are more mature compared with those from the Shuanghe and Baoxiangsi formations. The Jinsichang formation represents the products of a large fluvial system, whereas the Baoxiangsi formation is mainly dominated by local sources. The Shuanghe formation contains material from both distant sources and locally eroded materials. Detrital zircon U-Pb age patterns from the Jianchuan Basin are similar to those in sediments in the Gonjo, Simao, and Chuxiong basins, and show great similarity with the modern Jinshajiang River. Statistical analysis of the zircon ages suggests that the Songpan-Ganzi terrane was the primary source for all sediments, while the Yangtze Craton and northern Qiangtang terrane constitute secondary sources. Taken together these data confirm that a paleo-Jinshajiang flowed south toward to the South China Sea from the SE Tibetan Plateau in the late Eocene, constraining the age of formation of the First Bend. [ABSTRACT FROM AUTHOR]

The Yangtze River (YR) region and cities along the river have severe deterioration of air quality due to urbanization and economic development. Black carbon (BC) has significant impacts on air quality and climate, however it is poorly characterized across the region. Here we report the first continuous measurements of BC and gaseous pollutants along the YR in wintertime, with an intensive observation period from November 21 to December 4, 2015, covering ∼7° longitude over the continent in China. The highly polluted periods (HPP) with NOx >80 μg m−3 indicated more localized emissions. At the western (longitude <118°E) and eastern (longitude >118°E) ends of the YR valley, the HPP events reduced, mostly since the western end was influenced by terrain height and regional transport, and the eastern end was influenced by easterly oceanic or westerly continental air masses. In these regions, BC core size decreased by 5%–19% during the HPP, and had modes of mass median diameter in the range 120 –180 nm, which was found to be predominately from local sources, contrasting with a more consistent mode ∼200 nm that was due to BC from mixed sources. A comparison of simultaneously measured data from the nearby monitoring stations along the river demonstrated a high consistency of PM2.5 over the river, which reflected the important regional impact on the particulate mass. This study evaluates the shipping emission and regional influence over the YR and may guide the policy maker on mitigating air pollution. Key Points: The first continuous measurements of black carbon (BC) and gaseous pollutants along the Yangtze River were conducted in wintertime covering ∼7° longitude over the continent in ChinaBC core size decreased by 5%–19% during the highly polluted periods, and had modes of mass median diameter in the range 120 –180 nm, which was found to be predominately from local sources, contrasting with a more consistent mode ∼200 nm that was due to BC from mixed sourcesThe evaluation of the shipping emission and regional influence over the Yangtze River can underpin the mitigation strategies of air pollution [ABSTRACT FROM AUTHOR]

Dissolved inorganic carbon (DIC) in the East China Sea (ECS) is physically and chemically affected by the northward intrusion of the Kuroshio Branch Current (KBC) and the Changjiang River (CR) outflow. We trace these processes using dual DIC isotopic compositions (Δ14C and δ13C) along transects that begin in the CR and estuary, and extend out into middle shelf waters of the ECS. We especially focus on frequently occurred nearshore hypoxia, as they appeared in the summer of 2017. The Δ14C values (28.8‰--35.3‰) from the ECS mid-shelf water were comparable to the reported value from the Kuroshio Current (KC) at the continental slope (34.4‰ ± 7.4‰), but Δ14C values in the CR (-173.6‰ & -162.3‰) were substantially lower than observations made in 2014. We also found that the Δ14C of DIC in the bottom waters along the inner shelf, including hypoxic area, decreased from 25.0‰ to 18.5‰, from south to north. Water masses mixing between the CR and the ECS mid-shelf waters with and without organic carbon degradation can be identified in plots of Δ14C versus DIC-1. With simple mixing calculations, we show that the northward decreasing Δ14C of inner shelf bottom water is caused by downward transport of DIC with low Δ14C value mediated by biological process from the surface, as opposed to simple physical mixing. [ABSTRACT FROM AUTHOR]

A comparison is presented between groundwater storage trends derived from Gravity Recovery and Climate Experiment (GRACE) satellite measurements and trends derived from unregulated river baseflow observations in 19 catchments in tributaries of the Central Yangtze River. The two sets of trends are well correlated with a coefficient of r = 0.64, but the baseflow‐derived trends were found to be on average about 33% smaller than those based on the GRACE measurements. Although other factors undoubtedly play a role, the difference in trend magnitudes of the two sets of trends is concluded to be mainly due (i) to remaining uncertainties and complexities in GRACE data processing and (ii) to the likely gradual shrinking of the contributing catchment areas during the baseflow recession process. The present findings should be useful in extending GRACE measurements to longer periods on the basis of long‐term streamflow measurements and in recovering missing data. Key Points: Groundwater storage change estimates obtained by GRACE satellite measurements are compared with baseflow recession‐based estimatesWhile the trends were very similar, on average, the baseflow based trends were about 33% smaller than those based on GRACE dataThe characteristic drainage time scales of the investigated catchments in China were mostly consistent with observations elsewhere [ABSTRACT FROM AUTHOR]

Organic aerosols (OAs) have important influences on the climatic implications and health effects of atmospheric aerosols. Among the complex OA constituents, brown carbon (BrC) accounts for a substantial mass fraction and is of special interest because of its light‐absorbing properties. In this study, the chemical composition of atmospheric OAs over the middle‐lower Yangtze River (MLYR) channel, as well as the BrC, was investigated during a ship cruise campaign in winter 2015. In total, more than 1,000 molecular formulas were determined using a combination of ultra‐high performance liquid chromatography (UHPLC), a diode array detector (DAD), and Orbitrap high‐resolution mass spectrometry (HRMS). Large numbers and enhanced signal abundances for known tracers as well as monocyclic and polycyclic aromatics indicate that biomass burning and fossil combustion are important sources of OAs over the MLYR channel. In addition, 13 chromophores with strong light absorption, mostly representing established biomass burning tracers, were unambiguously determined by UHPLC/DAD/HRMS and contributed to 35–37% of the total light absorption of OAs at 290 nm and 58–70% at 350 nm. Sixty‐three previously identified biomass burning chromophores were also positively identified in the mass spectrometric analysis here but embedded in the humped signal during the spectroscopic analysis. These BrC chromophores exhibit high degrees of unsaturation, suggesting that these compounds are aromatic, nitro‐aromatic, and polycyclic aromatic type of species. Our results highlight the significant influence of biomass burning and fossil combustion on atmospheric OAs over the MLYR channel in the winter, strongly enhancing light‐absorbing properties and decreasing air quality. Key Points: More than 1,000 atmospheric particulate organics including 76 BrC chromophores were determined over the Yangtze River channelBrown carbon chromophores exhibit high degrees of unsaturation, suggesting that these compounds are aromatics, nitro‐aromatics, or polycyclic aromaticsBiomass burning tracers contribute significantly to the total light absorption of organic aerosols [ABSTRACT FROM AUTHOR]

From 29 June to 6 July 2016, China's Yangtze River Basin experienced heavy precipitation, causing more than 200 deaths and affecting tens of millions of people. Using ERA5 reanalysis, soundings, and satellite observations from FY‐2 and Global Precipitation Measurement (GPM), we reviewed this heavy rainfall event from the perspective of its meteorological triggers and the cloud microphysics. As the cloud system moved eastward from the Tibetan Plateau, precipitation particles got larger and denser, and the enhancement of stratiform precipitation contributed the most precipitation. The riming and aggregation processes, the dominant growth modes of particles, were significantly enhanced between 5.5 and 7 km. The increase in the echo‐top height had a considerable positive effect on the near‐surface particle size (from ~1.0 mm at 4 km to ~1.5 mm at 10 km), but this feature was not significant over the Tibetan Plateau. We suggest that the microphysics of this event was dominated by the combination of the eastward moving cloud system, which acted as continuous "seeder" cloud, and the increase in water vapor associated with the low‐level vortex and jet, which generated enhancing "feeder" cloud. The particles from the "seeder" cloud grew by the lower "feeder" cloud, thus increasing the particle size to enhance the precipitation. Overall, the generation and movement of such a cloud system is an important atmospheric disturbance for the generation of heavy precipitation downstream, and could be an early warning signal in the forecasting of heavy rainfall in China during the Meiyu period. Key Points: An event that produced a historical amount of rainfall in Wuhan during the Meiyu period is reviewedRiming and aggregation processes were enhanced as the cloud system moved out of the Tibetan PlateauThe event was dominated by an eastward moving system acting as "seeder" cloud, together with the increasing water vapor acting as "feeder" cloud [ABSTRACT FROM AUTHOR]

Fluid mud (FM) is a unique sedimentary feature in high‐turbidity estuaries, where it can make a rapid contribution to morphodynamics. Insufficient field measurements and fixed‐point monitoring lead to deficient understandings of the formation, transport, and breakdown of the FM under extreme weather conditions. A field survey was conducted in the Changjiang Estuary during the period of turbidity maximum, just after Typhoon Haikui. The measurements captured the formation of the FM beneath the suspended layers, particularly around the lower reach of the North Passage. The thickness of the observed FM gradually decreased landward along the channel, with the maximum value reaching ~0.9 m. The major features of the observed storm‐induced FM were simulated using the Finite‐Volume Community Ocean Model. The results indicated that the initial appearance of the FM was the result of a typhoon‐intensified, salinity‐induced stratification in the outlet region. The subsequent landward propagation of the FM was driven by the combined effects of the FM‐induced mud surface pressure gradient force and saltwater intrusion near the bottom. Weak mixing during the subsequent neap tidal period sustained the FM as it rapidly extended into the middle region of the North Passage. This produced a large velocity shear at the interface of the FM and upper suspension layer, increasing the entrainment from the FM to the upper suspension layer. As a result of the increased tidal mixing, the FM weakened and then finally broke down in the subsequent spring tidal period. Plain Language Summary: The environment along the large river to estuary continuum is generally turbid and frequently produces highly concentrated benthic sediment suspensions, that is, fluid mud (FM). The FM is a sediment feature, with a concentration mostly in the range of 10 to >100 g/L. It is difficult to track the FM's movement and breakdown. The response of the FM to extreme atmospheric and oceanic conditions is therefore not well understood. In this study, a comprehensive field campaign identified the large‐scale formation of the FM after a severe tropical storm in the Changjiang Estuary. The life cycle of the FM in this estuary cannot, however, be determined through the field observation alone. A two‐layer FM model was developed to achieve this goal. The experiments suggested that the key physical factor was the stratification resulting from the typhoon‐enhanced saltwater intrusion. This led to the formation of the FM in the near‐bottom layer. After the FM formed, it extended onshore along the channel under the influence of an ambient saltwater intrusion. The FM was constrained in the benthic layer as a consequence of weak mixing from the saltwater intrusion. The breakdown of the FM was governed by enhanced tidal mixing in the subsequent spring tide. Key Points: A strong fluid mud (FM) formed during the passage of a tropical stormA storm‐increased stratification initially triggered a massive formation of the FMThe FM was sustained and transported by saltwater intrusion, and it subsequently broke down during the strong‐mixing spring tide [ABSTRACT FROM AUTHOR]

Chemical composition of river sediments and dissolved load is classically used to infer controls on continental weathering and, therefore, exert an important role on the understanding of the global carbon and biogeochemical cycles. To date, most studied river basins are strongly impacted by dam constructions; however, the effects of dams on sediment chemical compositions are little known. The Three Gorges Dam is one of the largest dams in the world and began impounding water in 2003 in the Changjiang basin. In order to investigate the impact of this dam on downstream sediment chemistry, temporal variation of sediment weathering intensity is reported here based on analyzed and compiled data between 1997 and 2018. Downstream sediments collected before 2003 are characterized by weak weathering intensity, in agreement with the overwhelming flux and fast transfer of sediments derived from the mountainous upper watershed. After the Three Gorges Dam operation, strong midlower riverbed erosion changed the roles of the midlower reaches from important sinks to major sources of sediments delivered to the East China Sea. This resulted in a progressive change of the sediment chemistry because the eroded midlower riverbed sediments were more deeply weathered, as confirmed by 150‐year‐old sediment cored in the lower mainstream and by mass‐balance calculations. This more intensive weathering may be explained by warmer climate and longer water‐rock interaction time in the midlower basin. Thus, this study suggests the need to quantify potential bias in weathering intensity and controls caused by damming activity in large river systems. Key Points: Sediments collected downstream of the Three Gorges Dam displayed progressive but significant increase in weathering intensity since 2003Simple mass balance calculation indicates progressive addition of strongly weathered sediments since the Three Gorges Dam operationA core collected in the lower mainstream demonstrates that in situ weathered midlower riverbed sediments correspond to the missing source [ABSTRACT FROM AUTHOR]

Lateral flow significantly contributes to the near‐bottom mass transport of salinity in a channel‐shoal system. In this study, an integrated tripod system was deployed in the transition zone of a channel‐shoal system of the Changjiang Estuary (CE), China, to observe the near‐bottom physics with high temporal/spatial resolution, particularly focusing on the lateral‐flow‐induced mass transport. These in situ observations revealed a small‐scale salinity fluctuation around low water slack during moderate and spring tidal conditions. A simultaneous strong lateral current was also observed, which was responsible for this small‐scale fluctuation. A high‐resolution unstructured‐grid Finite‐Volume Community Ocean Model has been applied for the CE to better understand the mechanism of this lateral flow and its impact on salinity transport. The model results indicate that a significant southward near‐bed shoal‐to‐channel current is generated by the salinity‐driven baroclinic pressure gradient. This lateral current affects the salinity transport pattern and the residual current in the cross‐channel direction. Cross‐channel residual current shows a two‐layer structure in the vertical, especially in the intermediate tide when the lateral flow notably occurred. Both observation and model results indicate that near‐bottom residual transport of water moved consistently southward (shoal to channel). Mechanisms for this intratidal salinity variation and its implications can be extended to other estuaries with similar channel‐shoal features. Plain Language Summary: In channel‐shoal systems, lateral processes sometimes can be of great significance, for example, influencing salinity and sediment transport, even some biogeochemical matters that influence the water environment. Salinity and sediment transport will have a further effect on navigability, ecology, and so on, for example, sediment deposition issues, which significantly decrease the shipping capacity. Consequently, knowing the accurate information about the flow field and finding a criterion for pronounced lateral processes are important to better understand hydrodynamics and sediment behaviors in channel‐shoal systems. Here in this study, we conducted an in situ observation and used numerical simulation to detect and predict a strong lateral flow in the North Passage of the Changjiang Estuary. This shoal‐to‐channel lateral flow occurred around the end of ebb and caused an intratidal salinity variation at the observation site, close to the deep channel. Therefore, a link between pronounced lateral flows and typical salinity variation can be established. This link can also be found in other estuaries like Hudson River estuary. Findings presented here will help to easily distinguish pronounced lateral flows and better understand the effect of lateral flows. Key Points: Intratidal salinity variation (ISV) and a strong lateral flow in a channel‐shoal system were identified by an integrated tripod systemNumerical simulation reveals that lateral flows were primarily driven by the salinity‐induced pressure gradient forceLateral flows can be generated or enhanced by human interventions such as groyne fields [ABSTRACT FROM AUTHOR]

Opsariichthine (sensu Oceanologi Et Limnologia Sinica, 1982, 13, 293–298) is a cyprinid group consisting of five genera and endemic to East Asia. Previous studies suggested that there may be many possible cryptic species in this group, but this has not been confirmed. In this study, using mitochondrial cyt b sequences on 1,388 samples and 739 haplotypes, we showed very high species diversity within this group. The results showed that phylogenetic relationships of the opsariichthine group were as ([Nipponocypris‐Parazacco‐Candidia] + [Zacco + Opsariichthys]), and there were multiple deep lineages within several species, flagging putative cryptic species. When a 3% genetic distance was used as a threshold for species delimitation, 35 haplogroups were found, nine haplogroups in Candidia‐Parazacco‐Nipponocypris group, six haplogroups in the Zacco group, and 20 haplogroups in the Opsariichthys group. We consider all of them to be putative until determination of distinct species based on the tree topology, geographic distributions, or a combination of both. In addition, two kinds of species delimitation tools, ABGD and PTP, were applied to construct molecular operational taxonomic units (MOTUs). The ABGD method revealed nine MOTUs in Candidia‐Parazacco‐Nipponocypris group, two MOTUs in the Zacco group, and 17 MOTUs in the Opsariichthys group. And the PTP method revealed 10 MOTUs in Candidia‐Parazacco‐Nipponocypris group, 10 MOTUs in the Zacco group, and 29 MOTUs in the Opsariichthys group. Therefore, there should be more species in the opsariichthine group than presently described. Based on the molecular data and morphological characteristics, we proposed Opsariichthys macrolepis as a valid species and described its morphological diagnostic characters. In this study, we used more samples to investigate the hidden species diversity in opsariichthine fish based on mitochondrial cyt b sequences. The results revealed very high species diversity in this group. Based on the molecular data and morphological characters, we proposed that Opsariichthys macrolepis is a valid species which from the upper Yangtze River and described its morphological diagnostic characters. [ABSTRACT FROM AUTHOR]

The Qinling orogenic belt is a complex subduction–accretion–collision orogen that welded the North China Craton and the Yangtze Craton during the final continental collision in the Triassic. The Xiong'ershan area, located in east Qinling, exposes a typical Triassic syenite pluton and several contemporaneous Mo, Au, and Cu deposits. The aegirine–augite syenites and syenites from the Mogou pluton are characterized by alkalic to peralkalic (total alkali Na2O + K2O = 13.95–14.63 wt.%, CaO = 0.06–2.87 wt.%), and shoshonitic features (K2O = 11.86–14.34 wt.%). Zircon LA–ICP–MS U–Pb dating of the aegirine–augite syenite and syenite yield emplacement ages of 232.5 ± 0.6 and 221.8 ± 0.7 Ma, indicating multiple pulses of magmatism. Evidence from zircon Hf isotopes; occurrence of mafic microgranular enclaves; heterogeneous peralkaline composition; and wide ranges of MgO, Ni, and other trace elements suggest that the parental magma was mainly sourced from partial melting of Archean to Paleoproterozoic crustal sources, mixed with juvenile mantle‐derived mafic magmas. The Mogou pluton was probably emplaced in the tectonic transition from syn‐collision to post‐collision settings and accompanying slab break‐off process, from the commencement of collision at approximately 245 Ma and post‐collisional extension at approximately 210 Ma. Gold, molybdenum, and copper deposits formed during the interval of 255–208 Ma, and the close temporal and spatial relationship between these Triassic polymetallic deposits and the Mogou alkaline pluton invokes a genetic linkage. The heat source for magmatism and related metallogeny is correlated to a hot upwelling asthenospheric mantle that caused partial melting of the Archean to Paleoproterozoic crustal basement, resulting in magma mixing between the two end‐members. [ABSTRACT FROM AUTHOR]

Observed oxygen concentrations collected at discrete locations during research cruises were conventionally used to estimate spatial extents of bottom low‐oxygen/hypoxia. Yet observed oxygen concentrations were often not quantitatively representative of spatial patterns in instantaneous oxygen concentrations in coastal oceans, especially when the bottom hypoxia was transient. Over the Changjiang River estuary and its adjacent sea, research cruises could easily be longer than the time scale of variability of bottom hypoxia extent. The Changjiang River plume is extremely mobile due to changes in wind magnitude and direction, and the redistribution of this freshwater cap strongly regulates vertical stratification on which bottom hypoxia formation depends. A high‐resolution ecosystem model was developed, which successfully reproduced observed temperature, salinity, and bottom oxygen concentration. This model suggested fast response of bottom oxygen to vertical stratification evolution (generally ∼6–50 hr) and a transient spatial extent of summer bottom hypoxia off the Changjiang River estuary. Comparisons between observed and modeled oxygen concentrations implied that the hypoxic area calculated from dissolved oxygen at discrete locations often had possible errors and the estimated magnitude of hypoxic area which depended on the chronological order of observations. Therefore, it is risky to estimate the spatial extent of hypoxic area based on observations exclusively, and the relevant quantification of annual hypoxia area trend is also questionable. Integration of quasi‐simultaneous observations is required to advance the understanding of oxygen dynamics, to minimize observational uncertainties. The development of skillful ecosystem models that profit from ample observations and have the power to reproduce dissolved oxygen is indispensable. Plain Language Summary: Oxygen concentrations collected during research cruises are conventionally used to estimate bottom low‐oxygen/hypoxic area. Research cruises over Changjiang River estuary and the adjacent sea generally take 1–3 weeks; however, the time scale of variability of bottom hypoxic area is much shorter. Thus, observed oxygen concentration is often not quantitatively representative of instantaneous oxygen concentration for this region, and the estimated hypoxic area during a cruise is often biased. A qualified ecosystem model suggests fast response of bottom oxygen to vertical stratification evolution (generally 6–50 hr) and transient spatial extent of summer bottom hypoxia. Changjiang River plume is extremely mobile due to changes in wind magnitude and direction, and the redistribution of this fresh cap strongly regulates vertical stratification on which bottom hypoxia formation and sustain depend. Wind‐induced fresh water redistribution and the consequent evolution of vertical stratification are proved to drive short‐time changes of bottom oxygen via controlling air‐sea exchanges. We propose that ample observation is needed to advance understanding of realistic oxygen dynamics. To minimize biases and to exhibit bottom hypoxia condition in perspective, development of skillful ecosystem models that profit from the ample observation and have the power to reproduce is indispensable. Key Points: Bottom hypoxia off the estuary is transient due to the mobile Changjiang River plumeObserved hypoxic areas during research cruises often have possible errors due to high variabilityIntegration of sufficient observations and skillful ecosystem models is indispensable [ABSTRACT FROM AUTHOR]

Abstract: Water‐level variations are an internal aspect of lake ecosystems that play a key role in structuring aquatic diversity and providing ecosystem services. In this study, the hydrologic alteration of Dongting Lake induced by the Three Gorges Dam (TGD) was assessed using indicators of hydrologic alteration and range of variability approach. The results demonstrate a declining trend in autumn water level (0.52–2.26 m) and 5–35 days' advancement for date of minimum annual water level because of the impound of water by the TGD in early autumn. The spatial patterns in the degree of the indicators of hydrologic alteration were different among the sub‐lake regions. Annual minimum water level and timing of annual extreme water level suffered a high degree of alteration in the eastern part of the lake, whereas autumn water level, date of minimum water level, and number of reversals in the western part of the lake showed a high degree of alteration. The average integrated degree of hydrologic alteration (D0) for Dongting Lake was 50.40%, indicating that the hydrologic regime suffered a moderate alteration. The most ecologically relevant hydrologic indicators are critical for understanding eco‐hydrology. On the basis of principal component analysis, the five selected ecologically relevant hydrologic indicators were 90‐day minimum, date of minimum, high pulse duration, date of maximum, and May water level. Further studies are required to understand the impact of the TGD on water conditions in Dongting Lake, especially related to the response of the aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Understanding climate change impacts on hydrological regime and assessing future water supplies are essential to effective water resources management and planning, which is particularly true for the Tibetan Plateau (TP), one of the most vulnerable areas to climate change. In this study, future climate change in the TP was projected for 2041–2060 by a high‐resolution regional climate model, RegCM4, under 3 representative concentration pathways (RCPs): 2.6, 4.5, and 8.5. Response of all key hydrological elements, that is, evapotranspiration, surface run‐off, baseflow, and snowmelt, to future climate in 2 typical catchments, the source regions of Yellow and Yangtze rivers, was further investigated by the variable infiltration capacity microscale hydrological model incorporated with a 2‐layer energy balance snow model and a frozen soil/permafrost algorithm at a 0.25° ×0.25° spatial scale. The results reveal that (a) spatial patterns of precipitation and temperature from RegCM4 agree fairly well with the data from China Meteorological Forcing Dataset, indicating that RegCM4 well reproduces historical climatic information and thus is reliable to support future projection; (b) precipitation increase by 0–70% and temperature rise by 1–4 °C would occur in the TP under 3 RCPs. A clear south‐eastern–north‐western spatial increasing gradient in precipitation would be seen. Besides, under RCP8.5, the peak increase in temperature would approach to 4 °C in spring and autumn in the east of the TP; (c) evapotranspiration would increase by 10–60% in 2 source regions due to the temperature rise, surface run‐off and baseflow in higher elevation region would experience larger increase dominantly due to the precipitation increase, and streamflow would display general increases by more than 3% and 5% in the source regions of Yellow and Yangtze rivers, respectively; (d) snowmelt contributes 11.1% and 16.2% to total run‐off in the source regions of Yellow and Yangtze rivers, respectively, during the baseline period. In the source region of Yangtze River, snowmelt run‐off would become more important with increase of 17.5% and 18.3%, respectively, under RCP2.6 and RCP4.5 but decrease of 15.0% under RCP8.5. [ABSTRACT FROM AUTHOR]

ABSTRACT In the present study, characterization of columnar aerosol optical properties and classifying the major aerosol types was investigated at an urban-industrial city, Nanjing in the Yangtze River Delta ( YRD) region over East China using simultaneous data sets retrieved from the MODerate resolution Imaging Spectroradiometer ( MODIS) and Ozone Monitoring Instrument ( OMI) sensors during 2004-2015. A notable spatiotemporal heterogeneity was observed in the optical properties of aerosols on the seasonal scale over East China. Aerosol optical depth at 550 nm ( AOD550) exhibited pronounced seasonal variability over Nanjing in the YRD, with higher values during summer and spring seasons and lower in winter. Ångström exponent ( AE470-660) found higher in summer indicating the relative abundance of fine mode aerosols over the coarse mode. We also used the Hybrid Single Particle Lagrangian Integrated Trajectory ( HYSPLIT) model for presenting cluster trajectory analysis which revealed that the airmasses from different source regions contributed greatly to aerosol loading during the study period. In addition, we followed two techniques for studying classification of major aerosol types based on the predefined thresholds. Using the AOD-AE method (here called as Technique-I), five major aerosol types were identified via, continental clean ( CC), marine ( MA), biomass burning/urban-industrial ( BU), desert dust ( DD), and mixed ( MX). In all the seasons, MX is the dominant aerosol type followed by the BU and DD type aerosols during summer and spring seasons, respectively. Further, the sub-classification of aerosol types was carried out considering into account of the characteristics of absorbing aerosol index ( AAI) (here called as Technique- II). The two clustering techniques showed reasonable consistency in the obtained results. The various aerosol types (absorbing and non-absorbing) and their change over a region are highly helpful in fine tuning the models to decrease the uncertainty in the radiative and climatic effects of aerosols. [ABSTRACT FROM AUTHOR]

ABSTRACT: Using the National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis and National Oceanic and Atmospheric Administration extended reconstructed sea surface temperature (SST) data sets, we examine the preceding factors in the Atlantic Ocean contributing to summer high temperature anomalies over the lower reaches of the Yangtze River basin–Jiangnan (LRYB–JN) region. We find that summer LRYB–JN surface air temperature (SAT) anomalies are highly correlated with, and physically connected to, the preceding winter SST and SAT anomalies in the tropical western Atlantic (TWA) region [(10°–30°N, 60°–35°W) and (0°–10°N, 50°–35°W)]. The effect of preceding winter thermal conditions in the TWA region can be explained by the following two mechanisms. Coupled with SST, positive TWA SAT anomalies can persist from the preceding winter to summer and excite a zonal wave train at middle latitudes extending from the Atlantic to Eurasia, with a deep and stable high pressure anomaly centred over the LRYB–JN region. As a result, high temperature anomalies occur over the LRYB–JN region. In addition to the above mechanism, the TWA SST–SAT coupled anomalies also exert an impact on summer LRYB–JN SAT by modulating the tropical Indian Ocean (TIO) SAT and SST variation, which causes summer LRYB–JN SAT anomalies. Given the contributions of TWA SAT anomalies, independent of and in concert with the TIO SAT variation, we define a preceding winter TWA–TIO SAT index, which measures the concurrent variation of TWA and TIO SATs. The preceding winter TWA–TIO index is more significantly correlated with the summer LRYB–JN SAT and therefore can reflect the latter better than the individual TWA or TIO SAT index. [ABSTRACT FROM AUTHOR]

The Yangtze (Changjiang) River enters the East China Sea with huge annual freshwater and sediment deposits. This outflow, known as the Changjiang diluted water ( CDW), causes striking ecological gradients that potentially shape coastal species' distribution and differentiation. The CDW has long been rendered as a marine biogeographic boundary separating cold-temperature and warm-water faunas, but it remains unclear whether and to what extent it acts as an intraspecific barrier. Here, we synthesize published phylogeographic studies related to the CDW to address these issues. We find that the influence of the CDW on population differentiation is taxonomically variable, and even congeneric species may respond differently. In studies that claim the CDW is a phylogeographic barrier, the underlying assumptions explaining observed genetic breaks are sometimes incorrect, and some may have misinterpreted results due to conceptual confusion or insufficient geographic sampling. After excluding these studies, the remaining ones generally show shallow genetic divergence but significant population structure for coastal species across the CDW, suggesting that the CDW has not been a historically persistent barrier, but rather has acted as a filter within some species recently, probably after the last glacial maximum. [ABSTRACT FROM AUTHOR]

The author discusses a study which found that dolphins can act as an indicator of population trend in a degraded freshwater systems. He states that the study used the recollections from local fishing communities to compare population declines from sightings among four dolphin species in the Yangtze River, China. He states that the study observed a similar rates of decline in most recent sightings among three of the Yangtze species.

During the summers of 2009 and 2013, seawater pH and concentrations of dissolved oxygen, inorganic carbon, and nutrients were measured off the Changjiang estuary in the East China Sea. The 2009 cruise captured the effects of Typhoon Morakot; the 2013 cruise sampled more typical conditions (no typhoon). Data from both years indicate a close correlation between high primary productivity in surface waters and hypoxia in bottom waters. Based on these observations, we developed a conceptual model to guide an exploration of processes contributing to the formation of summertime bottom hypoxia. A mixing-model analysis of the 2009 data identified a surface diatom bloom as the major (70-80%) source of the organic carbon that decomposed and ultimately led to bottom water hypoxia. Within the Changjiang River plume, depth-integrated net biological production in the water column was 1.8 g C m−2 d−1, indicating strong autotrophic production, which in turn led to a high respiration rate of 1.2 g C m−2 d−1 in the bottom water. During both cruises, strong surface-to-bottom physical and metabolic coupling was evident. In 2009, storm-driven inputs of nutrients from elevated river discharge and strong vertical mixing helped to fuel the rapid development of a surface diatom bloom. Afterwards, stratified conditions re-established, newly formed labile organic matter sank, and bottom water oxygen was quickly consumed to an extent that hypoxia and acidification developed. To our knowledge, the observed rate of hypoxia and acidification development (within 6 d) is the fastest yet reported for the Changjiang River plume. [ABSTRACT FROM AUTHOR]

Jinshan Lake, a typical river-connected lake located at middle-lower reaches of the Yangtze River, was selected as the study area. By field investigation and laboratory annular flume experiment, Cr and Zn migration mechanism between sediment and overlying water was quantitatively analyzed under different water depth and shear stress conditions. The results showed that (i) the content of Zn and Cr in the sediment dropped obviously at shear stress of >0.05 N m−1. Zn was more likely to release from the sediment than Cr; (ii) For weak flow disturbance, a downward trend was observed for the dissolved Cr concentration due to the strong adsorption effects of fine particles with large specific surface areas on heavy metals. Dissolved Zn varied more greatly than Cr, because the conversion process between dissolved Zn and the particulate form was influenced to some extent by suspended sediment content; (iii) Under both weak and strong disturbance conditions the increasing rate of particulate Zn in overlying water was lower than Cr, which could demonstrate that Cr was more likely to be adsorbed to suspended sediment in the overlying water than Zn. [ABSTRACT FROM AUTHOR]

The sediment saturation recovery process (i.e. the adaptation of suspended sediment concentration [SSC] to local forcing) is the main feature of the non-equilibrium suspended sediment transport (SST) frequently occurring in fluvial, estuarine and coastal waters. In order to quantitatively describe this phenomenon, a series solution is analytically derived, including the evolution of both vertical SSC profile and near-bed sediment flux (NBSF), and is verified by net erosion and net deposition experiments, respectively. The results suggest that the sediment saturation recovery process involves vertically varying fluxes that are not represented correctly by depth-averaging. Consequently, a vertical two-dimensional (2D) combined scheme is established and applied respectively in to a dredged trench and to a sand wave feature to demonstrate this argument. By analyzing the variations of the calculated depth-averaged SSC and NBSF we reveal that the equilibrium state presented by the sediment carrying capacity (SCC) form of the NBSF, which is usually applied in depth-integrated SST models, lags behind the actual dynamic bed equilibrium state. Moreover, the key factor α, the so-called saturation recovery coefficient within this form, is not only a function of local Rouse number but also is influenced by the local SSC profile. Finally, a three-dimensional (3D) non-orthogonal curvilinear body-fitted SST model is developed and validated in the Yangtze estuary, China, combined with the in situ hourly hydrographic data from August 14-15, 2007 during spring tide in the wet season. Model results confirm that the vertically varying sediment saturation recovery process, the discrepancies between the actual and SCC form of NBSF and non-constant value of α are significant in actual real geomorphic cases. The quantitative morphological change resulting from variations in environmental conditions may not be correctly represented by uncorrected depth-integrated SST models if they do not treat the effects of vertical motion on the sediment saturation recovery process. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In many large estuaries there are significant variations in flow conditions due to the interaction between tide (with spring-neap changes) and river discharge (with wet-dry seasons), which is key to understanding the evolution of the morphology and the resultant equilibrium state. To explore whether there exists an equilibrium state, and what might control such a state in such a dynamic environment, both numerical and analytical methods have been used to investigate the relative importance of tide and river contributions to the work done locally and globally over a wide range of discharge conditions in the Yangtze estuary. In particular, we have quantified the contributions from the tidal flow, the river flow and the tide-river interaction in terms of energy and its dissipation under different river discharge conditions. Model results suggest that there is a state of minimum tidal work for the case representing the wet season, when river and tide are doing uniform work locally and minimum work globally, within the bi-directional tidal reach for tide and along the whole estuary for river. We also observe that the system is not optimized for other conditions (peak discharge and low flows during the dry season), but the system would tend to do the minimum work possible given the constraints on the system (e.g. imposed forcing conditions and available sediment supply). Results, therefore, are consistent with the use of these two energetic optimization principles, and the proposed method could be applicable to other alluvial estuaries. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Pelmatozoans diversified primarily during the Middle and Late Ordovician Period, with Early Ordovician records being much more limited, resulting in many gaps in our knowledge of the early stages of their diversification. Dissociated pelmatozoan ossicles have been found abundantly in one section in the Tonggao Formation ( Tetragraptus approximatus Biozone, Floian, Early Ordovician). Most of the ossicles are thecal plates and stem ossicles from hemicosmitoid and glyptocystitoid cystoids. Thecal plates of ' Cheirocrinus' sp., Polycosmites sp., and other plates of uncertain affinity are described. A different ossicle type, Pentagonopentagonalis (col.), may represent crinoid remains; this would be one of the earliest occurrences of the class. The thecal ossicles and columnals are all considered, as both sets of data are desirable to determine the most complete estimate of generic diversity. The echinoderm ossicles may have been transported in from shallower water palaeoenvironments and clusters of ossicles may represent coprolites or regurgitates. Estimates of Early Ordovician palaeogeography that place this site at 30°S or near the palaeoequator are supported by the physiological requirements of the primitive echinoderms described herein. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Using the finite volume method, a 2-D water-sediment coupled model was developed to investigate the transport mechanisms of water and sediment in Poyang Lake, the largest river-connected lake in China. Simulating water and sediment transport processes in an average water year revealed that the total volume of water and the amount of suspended sediment transported from the five main rivers upstream of Poyang Lake were approximately 1.56 × 1011 m3 and 1.25 × 107 t, respectively. The outputs of water and sediment from the lake to the downstream Yangtze River were approximately 2.17 × 1011 m3 and 1.53 × 107 t, respectively. During the wet season, especially between July and September, nearly 1.06 × 1010 m3 of water and 1.89 × 106 t of suspended sediment were transported upstream from the Yangtze River into the lake due to the high external water levels, which accounted for 4.88% and 12.35%, respectively, of the total annual transport from the lake into the Yangtze River. [ABSTRACT FROM AUTHOR]

The influence of hydrodynamics on the chemical composition of sediments is based on the uneven distribution of element abundances in different size fractions. In this study, 72 size-fractional sediments from the Huanghe (Yellow River) and Changjiang (Yangtze River) riverbeds were measured with XRD, SEM, ICP-AES and ICP-MS. The analysis results show that the mineral and chemical characteristics change with grain size in the Huanghe and Changjiang sediments. According to the principal components analysis, three independent geochemical factors were found. The first factor elements, Zr, Hf, Th, U, Y, La and TiO2 are influenced by the existence of heavy minerals. The second factor elements, Al2O3, alkalis, alkaline earth (excluding Ca and Sr) and most of the transitional metals are dominated by clay minerals. The third factor group includes Ca and Sr, which were controlled by calcium-bearing mineral contents and chemical weathering intensities. The various grain size distributions greatly affect the mineralogical and chemical compositions of bulk sediments. Compared to other size fractions, the 5-6PHI size fractions of the Huanghe and Changjiang sediments have special mineralogical and chemical compositions, and intermediate volume percentages. Weight or volume percentage of each size fraction may be more suitable than mean grain-size of the bulk sediment to elucidate the grain size effects. Chemical Index of Alteration (CIA) values increase steeply with decreasing grain size, while Weathering Index of Parker (WIP) values are relatively stable. Because of the big influence of the abundance of clay minerals on CIA values, it is questionable to use CIA as a proxy of weathering intensity. Considering the clay mineral effects, stability in values and heterogeneous material properties, WIP has the potential to indicate the chemical weathering intensity of sediments. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The impact of urbanization for a summertime rainstorm process in the Yangtze River Delta was investigated based on two 96 member ensembles using the Weather Research and Forecasting (WRF) model. Results show that the increase of precipitation mainly occurs downwind of the city belt in this region. The increase and decrease of precipitation forms two zigzag belts in the precipitation area. The t-test illustrates that the discrepancies of near-surface environment around the city belt, the precipitation downwind of the city belt as well as the atmospheric variables in the lower troposphere over the rain belt, caused by urbanization, is significant in such a short-term rainstorm process. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]