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This paper presents an empirical analysis of regional disparities from 2000 to 2012 based on a time series of data involving 74 cities within three mega-urban regions along Yangtze River in China. Differing from previous researches on inter-provincial and coastal/interior data, this paper provides a new perspective of mega-urban regions and their cities in China. By Coefficient of Variation and Analysis of Variance the selection of three mega-urban regions along Yangtze River reveals how the mega-urban regional disparities evolve among the east, middle and west up to date in China. In terms of general trend the mega-urban regional inequalities have been decreasing ever since the year around 2005. By traditional regression modeling this paper relates the mega-urban regional inequality and the alleviation to the urbanization and its focus on mega-urban regional development. The regression shows that the evolution of intra mega-urban regions disparities is negatively influenced by the urbanization with meaningful statistical significance from 2000 to 2012. The multilevel regression is further applied based on the nested hierarchical data structure. The results indicate a complicated relationship of the urban population density of the city level, the urbanization ratio of the mega-urban region level and the urban disparities in 2012. Finally limitations and further research advice are provided. [ABSTRACT FROM AUTHOR]

This paper characterizes the land-use changes of Wuhan in Yangtze River Basin between 1954 and 2020, and its impact on flood exposure. Using Landsat TM images, the study draws four land-use maps which refer to the years 1954, 1982, 2000 and 2020, to explore the spatial and temporal distribution of land-use changes, particularly concerning the distribution of urban areas near the Yangtze River Basin. This was followed by an analysis of the land-use changes during the 4 study periods, and a set of four levels of flood exposure are used to analyze the flood exposure of urban areas of Wuhan. The result shows that the extensive land-use changes have a negative impact on the flood exposure of Wuhan during the last two decades. Finally, this paper provides a quantitative analysis of the correlation between flood exposure and flood damage (using Spearman's rank correlation coefficient). The analysis indicates that there is an significant positive correlation between flood exposure and flood damage (or economic losses caused by floods), but the correlations between flood exposure and the number of people affected is different with previous assumptions. This paper is an initial effort to quantitatively analyze the impact of land-use changes on flood exposure of Wuhan in Yangtze River Basin, which can be used by stakeholders of the developing countries to develop contingency land-use plans to reduce the urban flood exposure and to address and prevent the damage and casualties caused by flood disasters. [ABSTRACT FROM AUTHOR]

With the rapid development of China's economy, air pollution is becoming extremely serious. The spatial-temporal evolution of air pollution is conducive to the management of air pollution. The paper is proceeded into three steps. Firstly, based on the generalization principal component analysis method, the comprehensive air pollution evaluation index is established. Then, the gravity center model is utilized to explore the spatial-temporal evolution of air pollution in Yangtze River Delta from January 2014 to December 2016. Finally, the contribution decomposition method is utilized to explore the contribution to gravity center evolution. The main results are as follows: (1) The air pollution have obvious seasonal and regional differences in Yangtze River Delta. (2) The gravity center of air pollution continues to westward after 2014 with the characteristic of the north-south circular movement. (3) Hefei City and Yangzhou City have huge impact on the gravity center evolution of air pollution. The conclusions could be helpful for Chinese government to control the air pollution in Yangtze River Delta. [ABSTRACT FROM AUTHOR]

In this paper, we explored the trends of the atmospheric moisture budget, precipitation, and streamflow in summer during 1961 to 2005 and possible correlations between them by using the linear regression method in the Yangtze River basin, China. The results indicate that: (1) increasing tendencies can be detected in the atmospheric moisture budget, precipitation and streamflow in the Yangtze River basin; however, the significant increasing trends occur only in the atmospheric moisture budget and precipitation in the middle and lower Yangtze River basin; (2) both the ratio of summer moisture budget to annual moisture budget and the ratio of summer precipitation to annual precipitation exhibit a significant increasing trend in the Yangtze River basin. The ratio of summer streamflow to annual streamflow is in a significant increasing trend in Hankou station. Significant increasing summer precipitation can be taken as the major controlling factor responsible for the higher probability of flood hazard occurrences in the Yangtze River basin. The consecutively increasing summer precipitation is largely due to the consistently increasing moisture budget; (3) the zonal geopotential height anomaly between 1991 and 2005 and 1961 and 1990 is higher from the south to the north, which to a large degree, limits the northward propagation of the summer monsoon to north China. As a result, the summer moisture budget increases in the middle and lower Yangtze River basin, which leads to more summer precipitation. This paper sheds light on the changing properties of precipitation and streamflow and possible underlying causes, which will be greatly helpful for better understanding of the changes of precipitation and streamflow in the Yangtze River basin. [ABSTRACT FROM AUTHOR]

China is predicted to have higher drought risk with global warming, and for better preparedness and mitigation, it is necessary to find out the risky areas and reveal the essential causes. This paper develops an integrated index of drought risk following the pressure-state-impact process in which drought hazard and vulnerability are reflected by two stages of pressure-state and state-impact, respectively. Accordingly, the network structure data envelopment analysis model is employed to calculate the degree of drought risk, hazard and vulnerability. Then, this study evaluates 31 provinces, municipalities and autonomous regions of China, and the tempospatial patterns of regional drought hazard, vulnerability and risk during 2006-2011 are presented. Moreover, the determinants of risk in different parts of China are also investigated. The results suggest that the northeast and southwest of China are more potential to be affected by drought due to the high degree of hazard and vulnerability. The dominant factor affecting drought risk in the northwest is vulnerability, because the hazard in this part is comparatively low. However, although the drought situation is severe in the middle and lower reaches of the Yangtze River and the southeastern coastal areas, the strong resilience to drought makes the risk remain low. It is concluded that the effective way to decrease drought risk is to promote the level of water efficiency and agricultural irrigation, so that low sensitivity and high adaptive capacity would contribute to vulnerability reduction. [ABSTRACT FROM AUTHOR]

In the late 1990s, China’s Yangtze and Yellow River Basins suffered devastating natural disasters widely attributed to the degradation of soil and water resources. The Government of China responded with a number of major environmental programs, the most expensive and influential of which, the Grain for Green (GfG) Program, was implemented widely from 1999. Under the GfG Program—also known as the Sloping Land Conversion or Conversion of Cropland to Forest Program—the central government compensates farmers to convert cropland on steep slopes or otherwise ecologically sensitive areas to forest or grassland. Its long-term success depends on households’ ability to make sustainable changes to their household income streams and income diversification strategies. In this paper, we use a difference-in-difference estimation approach to examine the role of migration as a household-level response to the GfG Program, testing the extent to which individuals migrate following a reduction in land available for farming. Importantly, we exploit 15 years of data on migration decisions and establish that participating and non-participating households were on parallel migration paths before the program, thus refuting a key threat to causality in a difference-in-difference model. We find that participating families do, in fact, choose migration as an income diversification strategy more frequently than non-participants. The program effects varied over time but peaked post-Great Recession in 2011 when migration rates in GfG households exceeded those of non-GfG households by 5.9% points (p = 0.003) or about 26%. Our findings should encourage policymakers that families are making long-term adjustments to their livelihood strategies to avoid poverty in anticipation of the eventual withdrawal of government supports. [ABSTRACT FROM AUTHOR]

Hedgerow intercropping systems were introduced in China in early 1990s. Achievements in research and extension of contour hedgerow intercropping in China during the past 15 years are reviewed here. Results reported in over 70 published papers have shown that hedgerow intercropping contributes to soil and water conservation, soil fertility amelioration, land productivity improvement, bioterrace formation, and gives more options for income generation based on local resources in mountain areas. Research and demonstration works on contour hedgerow systems have achieved success by integrating local resources and needs into the system, especially in the dry valleys of the upper reaches of the Yangtze River, and the Three Gorges region. Contour hedgerow intercropping has attracted the attention of researchers, policy-makers, and farmers, and has been taken as an alternative to implementation of the Grain for Green policy, and ecological reconstruction and restoration today. To date, hedgerow intercropping has been demonstrated and applied practically on sloping land in more than six provinces of China, particularly Sichuan, Guizhou, Shanxi, Shaanxi, as well as in the Three Gorges region of Chongqing and Hubei Province. The intercropping system has also been practiced as an optimized technology for conserving farming on sloping lands, improving cash income, and reducing agricultural risks in depressed mountainous regions in southwest and northern China over recent years. Some misunderstandings and problems in studies and extension of the system in China are summarized and clarified, and some recommendations for further research and expansion of the system are also presented in this paper. [ABSTRACT FROM AUTHOR]

Recently some generalized autoregressive conditional heteroskedasticity (GARCH) models are proposed and applied to various hydrologic variables to capture and remove the ARCH effect, which has been observed frequently in the residuals from linear autoregressive moving average (ARMA) models fitted to hydrologic time series. As a nonlinear phenomenon of variance behavior, the ARCH effect reveals partially nonstationarity and nonlinearity of hydrological processes. This paper deals with the variation of a river basin using the ARMA-GARCH error model, which combines an ARMA model for modelling the mean behavior and a GARCH model for modelling the variance behavior of the residuals from the ARMA model. Based on the heteroscedasticity of hydrological variable series, the time-varying regional variance is proposed to check the variation of a river basin for the first time. As a study case, the method is applied to four deseasonalized daily discharge series from the middle reach of Yangtze River, China. Through the analyses of the conditional variance in different streamflow series, it is concluded that: (1) The ARCH effect exists in all the studied series which means the stream processes is nonstationary in terms of the variance; (2) The variations of time-varying variances are similar for the series from adjacent hydrological stations, and the similarity degree increases from upstream to downstream; (3) The regional variance is time-varying and can be used for further regional research. [ABSTRACT FROM AUTHOR]

Under the background of vigorously promoting the construction of ecological civilization, the importance of constructing the "non-waste cities" becomes increasingly prominent. Taking 39 cities in the Yangtze River Economic Zone as the research objects, this paper establishes a new evaluation index system for "non-waste cities," and proposes a multi-source, heterogeneous and multi-attribute decision-making method for the comprehensive evaluation of "non-waste cities." Specifically, the evaluation index system of "non-waste cities" is constructed from four aspects: economic level, environmental pollution, resource consumption, and waste utilization. Considering that there is the characteristic of multi-source heterogeneity for the attribute values (that is, real numbers, interval numbers, and fuzzy linguistic variables coexist), the multi-source heterogeneous data are uniformly converted into two-tuples, and then a new two-tuple entropy weight method is proposed to determine the weights of evaluation attributes. Moreover, combining the traditional grey relational analysis method with TOPSIS, a multi-source, heterogeneous and multi-attribute decision-making method based on two-tuple mixed correlation degree (TTMCD-MSHMADM) is proposed to evaluate the "non-waste cities," and an empirical analysis is made for the 39 cities in the Yangtze River Economic Zone. The result gives a theoretical basis for the formulation of sustainable economic development policies in the Yangtze River Economic Zone, and provides a decision reference for selecting the demonstration cities of "non-waste cities." [ABSTRACT FROM AUTHOR]

As the large-scale cascaded reservoirs have been developed rapidly in recent years, river basin flood control (RBFC) has become a complex, multi-objective and multi-reservoir problem. In order to realize the optimal operation and management of reservoirs in mainstreams and branches, this paper presents a generalized multi-objective flood control model (MOFCM) for joint optimal dispatching of cascade reservoirs, which is applied to cascade reservoirs in lower reaches of Jinsha River and Three Gorges Reservoir in Yangtze River (JFCR-TGR). Meanwhile, a multi-objective cultural self-adaptive electromagnetism-like mechanism (MOSEM) algorithm is introduced to solve RBFC problem. In the case study, comparing with the natural runoff of the Chuan River, the maximum release of optimal schemes is lesser, its reduced range is from 1727 to 12,887 m/s and the flood peak deduction rate is from 6.4 to 48 %. Results of case studies demonstrate that MOFCM is practicable and efficient for multipurpose multi-reservoir flood control. The optimal operation schemes obtained by MOSEM in JFCR-TGR system can be used to assist the decision makers in choosing the most efficient scheme. Furthermore, MOFCM can accomplish multiple-object optimization effectively under various scheduling situations. [ABSTRACT FROM AUTHOR]

By Hirschman-Herfindahl Index, the paper measures the spatial structure transformation of the Chinese container port system from the perspective of cargo flow in recent 13 years. It indicates that the spatial structure of container port system enters into 'the challenge of the periphery' phase as a whole, the decentralization of container flow become the mainstream tendency of the spatial variation of China's container port system; on the other hand, the spatial structure of container port system shows different characteristic in seven port regions, such as low-level equilibrium, single-gateway, multi-gateway and so on. It is a fact that multi-gateway port region of container port system has formed in Yangtze River Delta and Pearl River Delta region. Economic and foreign trade development, government macro-control and policy guidance, challenge of the periphery, network expansion of the terminal operators and shipping liners are the main driving forces for these new phenomena. [ABSTRACT FROM AUTHOR]

The eastern route of the South-to-North Water Diversion (SNWD-ER) project is a massive-scale interbasin system to transfer water from the Yangtze River to North China. With the infrastructure construction close to completion, the project is now faced with many complicated operations management problem at different levels. The problems are unique in that, on the one hand, the project is expected to be financially self-sustainable by charging water usages, and on the other hand, the water price is regulated for its nature as a social product. One such problem is to achieve a rational water allocation among different users by appropriate pricing schemes. In this paper, we study how to use a two-tier pricing scheme to balance the water allocation by using a Stackelberg game model. From the study, we find that (1) the Stackelberg game always has equilibrium solutions to balance the benefit of every party in the system, which implies that the two-tier pricing scheme can effectively coordinate the water allocation; (2) the two-tier pricing scheme can also result in multiple desirable by-products such as encouraging the implementation of water saving mechanism and giving the local water users certain priority; and (3) the government can adjust the pricing parameters to control and balance the profit of every party. As such we conclude that the two-tier pricing scheme is an effective way that integrates both the government control and market powers to ensure the public interest and the economic benefit, which is suitable for SNWD-ER project. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this paper is to assess the regulation of the accumulation of heavy metals in the aquatic environment and different fish species. Methods: Water and fish samples were collected from upper to lower reaches of the Yangtze River. The heavy metal (Cd, Cr, Cu, Hg, Pb, Zn) concentrations in the muscle tissue of seven fishes were measured. Additionally, the relationships between heavy metal concentrations in fish tissue and fish size (length and weight), condition factor, water layer distribution, and trophic level were investigated. Results: Metal concentrations (milligrams per kilogram wet weight) were found to be distributed differently among different fish species. The highest concentrations of Cu (1.22 mg/kg) and Zn (7.55 mg/kg) were measured in Pelteobagrus fulvidraco, the highest concentrations of Cd (0.115 mg/kg) and Hg (0.0304 mg/kg) were measured in Silurus asotus, and the highest concentrations of Pb (0.811 mg/kg) and Cr (0.239 mg/kg) were measured in Carassius auratus and Cyprinus carpio. A positive relationship was found between fish size and metal level in most cases. The variance of the relationships may be the result of differences in habitat, swimming behavior, and metabolic activity. In this study, fishes living in the lower water layer and river bottom had higher metals concentrations than in upper and middle layers. Benthic carnivorous and euryphagous fish had higher metals concentrations than phytoplankton and herbivorous fish. Generally, fish caught from the lower reach had higher metals concentrations than those from the upper reach. Conclusions: Cadmium and lead concentrations in several fishes exceeded the permissible food consumption limits, this should be considered to be an important warning signal. [ABSTRACT FROM AUTHOR]

China is entering a critical and accelerating phase of urbanization. As one of the most urbanized regions in China, the Changjiang (Yangtze) River Delta has experienced dramatic urbanization and urban transformation. However, in the recent years, many changes have taken place in this region and there is limited attention to the regional urbanization path evolution, its problems and the way to solve these problems. Therefore, we should revisit the urbanization process in the Changjiang River Delta again. In this paper, we revisited urbanization paths of the Changjiang River Delta by data analysis, influence factors of urbanization by the Gray Relational Analysis, and major challenges to urbanization of the Changjiang River Delta by theoretical considerations. We found that the urbanization of the Changjiang River Delta had experienced several stages of large-scale spatial and urban system restructuring. Within the Changjiang River Delta, Shanghai, Zhejiang and Jiangshu had experienced different urbanization path with local characteristics. But with their development model gradually converging, their urbanization model is also converging. We also found that the major influence factors affecting the Changjiang River Delta urbanization were dynamic change and urbanization was driven by different key factors in different socio-economic development stages. Meanwhile, the Changjiang River Delta urbanization is facing many problems such as existing institutional arrangements, including the hukou (household registration) system and others which can not meet the needs of current socio-economic development and urbanization. Therefore, it is imperative to promote institutional innovation and adopt a new urbanization development strategy for the sake of the orderly and sustainable urbanization development in the Changjiang River Delta. [ABSTRACT FROM AUTHOR]

The impoundment of the Three Gorges Dam (TGD) has disturbed the hydrological regime downstream and has directly affected the relationship between the Yangtze River and Dongting Lake. To trace the realistic and potential impacts, this paper examined the changes of the channel morphology and sedimentology caused by the TGD through a field survey on the channel cross-sections and then analyzed the impact on lake water level through BP neural networks. The possible impacts on inundation patterns in lake wetlands were studied based on the lake basin DEM. The results indicate that drastic sediment decline and severe channel erosion are putting considerable pressure on the river and lake. Changing river channels are evident in some monitoring cross-sections. Dongting Lake, for the first time, changed from trapping to supplying net sediment to the Yangtze River. During the water storage periods of the TGD, the water level decreased 2.03 m in 2006 and 2.11 m in 2009 at the outlet of the lake, with extreme decreases up to 3.30 m and 3.02 m, respectively. These changes have inevitably induced alterations in the inundation patterns of the lake wetlands, which in turn have disturbed the ecological function of lake wetlands as habitats for both migratory birds and aquatic fish. The serious droughts in Dongting Lake recent years were largely connected with the above changes. Therefore, proper attention should be paid to this occurrence. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Engineering Geology & the Environment is the property of Springer Nature 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.)

Copyright of Bulletin of Engineering Geology & the Environment is the property of Springer Nature 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.)

Copyright of Bulletin of Engineering Geology & the Environment is the property of Springer Nature 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.)

Shortage and uneven distribution of water resources in China is becoming a serious constraint of sustainable development of the society and its economy. Being based on the systems theory, this paper discusses the coordinated relationship between the social-economic development, the ecological environment and the water resources of China. A special evaluation model has been developed and applied in order to compute the comprehensive evaluation index of water resource carrying capacity on the basis of selecting available annual data for each province of China, describe the water resource carrying capacity for each province, and, next, evaluate the total resource carrying capacity for China. As obvious from the results, the water resources do not match with the distribution of the population and with the state of economy. Chinese southwestern provinces have a relatively large potential of water carrying capacity. The Yangtze River basin, the Pearl River basin and the eastern coastal areas no longer possess an advantage in the water carrying capacity. Some regions, such as the North China Plain, and Northwestern China, e.g. Xinjiang Uygur Autonomous Region, Ningxia Hui Autonomous Region, and Gansu Province experience severe shortage of water resources, since the water supply system is overloaded. [ABSTRACT FROM AUTHOR]

Climate change and human disturbance drive catchment erosion and increase riverine sediment load sensitively in small and medium-sized watersheds. This is not always true in large basins, where aggregation and buffering effects have dampen the ability to determine the driving forces of sedimentation. Even though there are significant responses to sedimentation in large river basins, it is difficult to get a precise quantitative assessment of specific drivers. This paper develops a methodology to identify driving forces that change suspended sediment load in the Upper Yangtze river. Annual runoff and sediment load data from 1954 to 2005 at the Yichang gauging station in the Upper Yangtze basin, daily precipitation data from 60 meteorological stations, and survey data on reservoir sediment were collected for the study. Sediment load/rainfall erosivity (S/R), is a new proxy indicator introduced to reflect human activities. Since the mid-1980s, S/R in the Upper Yangtze has dramatically declined from 0.21 to 0.03 (×10 t ha h MJ mm), indicating that human activity has played a key role in the decline of the suspended sediment load. Before the mid-1980s, a higher average S/R is attributed to large-scale deforestation and land reclamation. A significant sediment decrease occurred from 1959 to 1961 during an extreme drought condition, and an increase in sedimentation in 1998 coincided with an extreme flood event, which was well recorded in the S/R curve. This indicates that the S/R proxy is able to distinguish anthropogenic from climate impacts on suspended sediment load, but is not necessarily indicatory in extreme climate events. In addition, typical drivers of riverine sediment load variation including soil conservation projects, reservoirs construction, and land use/cover change are discussed. [ABSTRACT FROM AUTHOR]

The occurrence of rice high-temperature damage (HTD) has increased with global warming. Cultivation of rice is seriously affected by the HTD in the middle and lower reaches of the Yangtze River, which directly affects food security in this region and in the whole of China. It is important to monitor and assess crop HTD using satellite remote sensing information. This paper reviews the recent development of monitoring rice HTD using optical remote sensing information. It includes the use of optical remote sensing information to obtain the regional spatial distribution of high temperatures, mixed-surface temperature retrieval for rice fields based on mixed decomposition information, the development of field and thermal infrared testing and modeling, and the satellite/ground-based remote sensing coupled method for monitoring rice HTD. Finally, the prospects for monitoring crop HTD based on remote sensing information are summarized. [ABSTRACT FROM AUTHOR]

This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model, cubic spline interpolating functions, and nonlinear regression methods. The source regions of the Yangtze and Yellow Rivers were selected as the research areas. Results illustrate that: (1) There is significant non-linear relationship between NPP and GT in various typical years; (2) The maximum value of NPP is 6.17, 5.87, 7.73, and 5.41 DM·t·hm·a respectively, and the corresponding GT is 7.1, 10.0, 21.2, and 8.9°C respectively in 1980, 1990, 2000 and 2007; (3) In 1980, the sensitivity of NPP to GT is higher than in 1990, 2000 and 2007. This tendency shows that the NPP presents change from fluctuation to an adaptation process over time; (4) During 1980∼2007, the accumulated NPP was reduced to 8.05, and the corresponding carrying capacity of theoretical livestock reduced by 11%; (5) The shape of the demonstration region of ecological compensation system, livelihood support system, and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development. [ABSTRACT FROM AUTHOR]

Abstract  This paper presents a new kind of material for use in highway embankments in the soft soil of the Yangzi River delta. The experimental study was carried out first to evaluate the effectiveness of the proposed material, using different mixtures of river sand, cement and expanded polystyrene beads. This was confirmed by numerical modeling which indicated both its suitability as regards strength and a reduced settlement compared with the general lime stabilized soil embankments. The environmental advantage is that it utilized river sand which has to be removed to retain the profile of the river bed. [ABSTRACT FROM AUTHOR]

This paper presents a water quantity operation scheme to resolve series of environmental problems which some waterfront bodies are faced with, such as frequent water-level fluctuation, sediment deposition, water quality degradation, water transparency depravation, and submerged aquatic plant disappearing. Neijiang, which is a typical tide-influenced waterfront body located within the Changjiang Delta, China has been considered as the research area. A 2-D environmental and ecological model coupled with water current, water quality, suspended sediment, algae growth, and water transparency is established and validated against the field investigated data, and the model can well reflect the dynamic processes of these factors in Neijiang. Three water quantity operation modes including self-introducing, pumping, and keeping quiescence are proposed. Based on different kinds of water demand of Neijiang and the actual water exchange ability, detailed water quantity operation schemes under different hydrologic conditions are studied with the established numerical model, and the changes of some living condition factors after water operation are forecasted and evaluated. Results show that water exchange and sediment deposition in Neijiang are apparently reduced after water operation in different level years. In addition, the water quality and transparency in Neijiang can keep a good status, and the living environment is improved for submerged aquatic plant restoration. This study provides an example to resolve environmental problems, improve living conditions and keep a healthy ecosystem for similar waterfront bodies. [ABSTRACT FROM AUTHOR]

This paper reviews the land cover changes on the Tibetan Plateau during the last 50 years partly caused by natural climate change and, more importantly, influenced by human activities. Recent warming trends on the plateau directly influence the permafrost and snow melting and will impact on the local ecosystem greatly. Human activities increased rapidly on the plateau during the last half century and have significant impacts on land use. Significant land cover changes on the Tibetan Plateau include permafrost and grassland degradation, urbanization, deforestation and desertification. These changes not only impact on local climate and environment, but also have important hydrological implications for the rivers which originate from the plateau. The most noticeable disasters include the flooding at the upper reaches of Yangtze River and droughts along the middle and lower reaches of Yellow River. Future possible land cover changes under future global climate warming are important but hard to assess due to the deficits of global climate model in this topographically complex area. Integrated investigation of climate and ecosystems, including human-beings, are highly recommended for future studies. [ABSTRACT FROM AUTHOR]

The ability to extract mitochondrial and nuclear DNA from ancient remains has enabled the study of ancient DNA, a legitimate field for over 20 years now. Recently, Y chromosome genotyping has begun to be applied to ancient DNA. The Y chromosome haplogroup in East Asia has since caught the attention of molecular anthropologists, as it is one of the most ethnic-related genetic markers of the region. In this paper, the Y chromosome haplogroup of DNA from ancient East Asians was examined, in order to genetically link them to modern populations. Fifty-six human remains were sampled from five archaeological sites, primarily along the Yangtze River. Strict criteria were followed to eliminate potential contamination. Five SNPs from the Y chromosome were successfully amplified from most of the samples, with at least 62.5% of the samples belonging to the O haplogroup, similar to the frequency for modern East Asian populations. A high frequency of O1 was found in Liangzhu Culture sites around the mouth of the Yangtze River, linking this culture to modern Austronesian and Daic populations. A rare haplogroup, O3d, was found at the Daxi site in the middle reaches of the Yangtze River, indicating that the Daxi people might be the ancestors of modern Hmong-Mien populations, which show only small traces of O3d today. Noticeable genetic segregation was observed among the prehistoric cultures, demonstrating the genetic foundation of the multiple origins of the Chinese Civilization. [ABSTRACT FROM AUTHOR]

Residues of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) and their environmental risks in surface sediments collected from the rivers and lakes in Yangtze River Catchment of Wuhan, China, are investigated in this paper. Based on dry weight (dw), the concentrations of ΣHCH ( α-, β-, and γ-HCH) and ΣDDT ( p p′-DDT, o p′-DDT, p p′-DDE, p p′-DDD) in sediments ranged from 0.10 to 21.10 ng g−1 (mean, 4.03 ng g−1 dw) and 0.79 to 35.61 ng g−1 dw (average, 6.93 ng g−1 dw), respectively. Compared with some published guideline values of organochlorine pesticides (OCPs) in sediments, the concentrations of HCHs were at safe levels while the DDT residues would pose adverse biological effects in this studied catchment. The distribution of OCPs in sediments indicated that the input of tributaries was an important factor for OCP residues in the mainstream of the Yangtze River. Levels of OCPs in the sediments were influenced by total organic carbon contents, clay contents, water contents, and pH values of sediments. The present study suggested that historical usage of technical HCH and DDT was the main reason for OCP residues in the sediments from both rivers and lakes. Furthermore, the composition of OCPs reflected additional sources of the holding usage of lindane and fresh inputs of dicofol mixture in this region. [ABSTRACT FROM AUTHOR]

Very often, inexact, uncertain, or vague hydrological data are encountered in water researches. Statistical and fuzzy set theories are applied to deal with hydrological uncertainty problems. In this paper, the basic concept of the rough set theory is introduced and its application to hydrological data is illustrated. The proposed method is applied to water environment and environment quality evaluation of the Hang Jiang River, a major branch of the Yangtze River, in China. Our numerical applications suggest that the rough set theory is a useful tool for analysis of inexact, uncertain, or vague hydrological data. [ABSTRACT FROM AUTHOR]

This paper presents major findings from a recent study aiming to systematically determine suitable river sections for local domestic water supply along the Yangtze River in Jiangsu Province, China. On the basis of analysis on the current riverbank utilization and bank stability, accessible and stable river sections in the region were selected. The water quality in these river sections was then studied using a two-dimensional unsteady flow and pollutant transport/transformation model, RBFVM-2D. The model was calibrated and verified against the hydrodynamic data, water quality data and remote sensing data collected from the river. The investigation on the pollution sources along the river identified 56 main pollution point sources. The pollution zones downstream of these point sources are the main threat for the water quality in the river. The model was used to compute the pollution zones. In particular, simulations were conducted to establish the relationship between the extent of the pollution zone and the wastewater discharge rate of the associated point source. These water quality simulation results were combined with the riverbank stability analysis to determine suitable river sections for local domestic water supply. [ABSTRACT FROM AUTHOR]

Abstract This paper reviews changes in the use of short-term climate information for water management in China after the 1998 Great Flood in the Yangtze River basin. This devastating flood is now believed to have been caused mainly by the 1997–98 El Niño event. Although the short-term climate forecasts and weather forecasts are considered to be useful in planning for flood prevention activities and for making key decisions during combating floods, the gap between the meteorological services (producers of climate forecasts) and water management agencies (users of climate forecasts) has grown in terms of credibility given to climate forecasting: weather services put more efforts on improving the technology for increasing forecast accuracy, whereas water managers put their efforts and investment into upstream ecological restoration and flood control systems. By reviewing the published and ‘gray’ (unpublished) literature, we found that assessments of the 1998 Great Flood in the Yangtze River basin really helped the central government and water resources agencies to recognize the weaknesses of the existing flood control system, the mismanagement in the ecological systems, and the need for developing a national water resource management plan to deal with the problems of ‘too much water, too little water, and very polluted water’. [ABSTRACT FROM AUTHOR]

This paper explores the demographic impacts of the implementation of the "Grand Development in West China" policies and environmental rehabilitation projects in the upper reaches of the Yangtze River. It analyses the interaction between the environmental reconstruction and environment-related migration in this region. The intertwined nature of environmental, ethnic, and poverty problems not only bears negatively upon the "alleviation of poverty conducing to the accruement of wealth" of the poverty-stricken population, but also hinders the rehabilitation of the environment. It brings forth some opinions regarding improving the capacity of regional sustainable development through environmental migration. [ABSTRACT FROM AUTHOR]

Meiyu onset (MO) over Yangtze-Huaihe River Valley (YHRV) possesses obvious characteristics of interannual variations. Based on NCEP/NCAR reanalysis data sets, NOAA OLR and ERSST data, the interannual variability of MO(IVMO) and its previous strong influence signal (PSIS) are investigated. The possible mechanisms that the PSIS affecting IVMO are also discussed. The results show that the previous CP-ENSO (Central Pacific El Niño/Southern Oscillation) event is the PSIS affecting IVMO and it has a better accuracy rate of short-term climate prediction and practicality. The MO is most likely to be late (early) with the warm (cold) phase of CP-ENSO in previous boreal February and spring. CP-ENSO affects MO mainly by means of EAP (East Asian-Pacific) or JP (Japanese-Pacific) teleconnection, in which the tropical western North Pacific anticyclone plays an important role. In the years of CP-ENSO warm phase, the tropical warm wet water vapor transportation to YHRV is late. The anomalous positive sea surface temperature near the equatorial central Pacific results in late northward jump of the west- ern Pacific subtropical high and late establishment of Indian southwest monsoon via air-sea interaction, which leads to late seasonal transition of the atmospheric circulations over East Asia from boreal spring to summer. Late seasonal transition of the atmospheric circulations and late tropical warm wet water vapor transport to YHRV are the primary reasons that cause the late MO. The situations are directly opposite in the years of CP-ENSO cold phase. [ABSTRACT FROM AUTHOR]

On the basis of investigations on the composition and contents of heavy metals in the domestic refuse in the Three-Gorges region of the Yangtze River, in combination with the experimental results, this paper deals with the distribution rule of heavy metals in the various compartments of an incineration system: leachate pool, fly ash and residue. It is concluded that in the leachate pool heavy metals should not be neglectable since about 30% of Pb and 10% of Cr are leached here; in the incineration system, above 74% of Cr, As and Pb exists in residue; above 96% of Hg exists in fly ash and the contents of Cd in fly ash are close to those of residue. It is also concluded that the physical conditions of incineration have a significant influence on the distribution of heavy metals in the incineration system. [ABSTRACT FROM AUTHOR]

The daily precipitation data at 720 stations over China for the 1957-2003 period during summer (May-August) are used to investigate the summer subseasonal long-cycle droughts-floods abrupt alternation (LDFA) phenomenon and a long-cycle droughts-floods abrupt alternation index (LDFAI) in the middle and lower reaches of the Yangtze River (MLYRV) is defined to quantify this phenomenon. The large-scale atmospheric circulation features in the anomalous LDFA years are examined statistically. Results demonstrate that the summer droughts-to-floods (DTF) in the MLYRV usually accompany with the more southward western Pacific subtropical high (WPSH), negative vorticity, strong divergence, descending movements developing and the weak moisture transport in the low level, the more southward position of the South Asia high (SAH) and the westerly jets in the high level during May-June, but during July-August it is in the other way, northward shift of the WPSH, positive vorticity, strong convergence, ascending movements and strong moisture transport in the low level, and the northward shift of the SAH and the westerly jets in the high level. While for the summer floods-to-droughts (FTD) in the MLYRV it often goes with the active cold air mass from the high latitude, positive vorticity, strong convergence, ascending movement developing and the strong moisture transport in the low level, and the SAH over the Tibetan Plateau in the high level, but during July-August it is often connected with the negative vorticity, strong divergence, descending movements developing and the weak moisture transport in the low level, the remarkable northward shift of the WPSH, the SAH extending northeastward to North China and the easterly jets prevailing in the high level over the MLYRV. In addition, the summer LDFA in the MLYRV is of significant relationship with the Southern Hemisphere annual mode and the Northern Hemisphere annual mode in the preceding February, which offers some predictive signals for the summer LDFA forecasting in the MLYRV. [ABSTRACT FROM AUTHOR]

The Yangtze River Economic Belt is one of the three national strategies of China, while flood risk is one of the most important concerns in the development of Yangtze River Economic Belt. In order to decrease the risks caused by floods, complete flood management system and adequate pre-arranged planning are desiderated to be researched in advance. This study considers two typical situations of flood risk, in which one is sluice-control situation in flood detention area and another is dike-break situation in flood-protected area, and proposes a framework for flood risk mapping. The results show that the losses caused by flood hazards are massive both in the two typical cases when extreme floods happen. The economic losses of different indicators are of great difference in flood detention area and flood-protected area, respectively. The framework effectively handles the complex boundaries in the Yangtze River Economic Belt and provides more accurate flood routing information. The evacuation plan module which has been incorporated in the framework also provides informative assistance for emergent action of evacuation under urgent condition. [ABSTRACT FROM AUTHOR]

There is a well-known seesaw pattern of precipitation between the tropical western North Pacific (WNP) and the Yangtze River basin (YRB) during summer. This study identified that this out-of-phase relationship experiences a subseasonal change; that is, the relationship is strong during early summer but much weaker during mid-summer. We investigated the large-scale circulation anomalies responsible for the YRB rainfall anomalies on the subseasonal timescale. It was found that the YRB rainfall is mainly affected by the tropical circulation anomalies during early summer, i.e., the anticyclonic or cyclonic anomaly over the subtropical WNP associated with the precipitation anomalies over the tropical WNP. During mid-summer, the YRB rainfall is mainly affected by the extratropical circulation anomalies in both the lower and upper troposphere. In the lower troposphere, the northeasterly anomaly north of the YRB favors heavier rainfall over the YRB by intensifying the meridional gradient of the equivalent potential temperature over the YRB. In the upper troposphere, the meridional displacement of the Asian westerly jet and the zonally oriented teleconnection pattern along the jet also affect the YRB rainfall. The subseasonal change in the WNP-YRB precipitation relationship illustrated by this study has important implications for the subseasonalto- seasonal forecasting of the YRB rainfall. [ABSTRACT FROM AUTHOR]

Majority of shallow floodplain lake ecosystems of the middle and lower reaches of the Yangtze River (China) have gone through serious eutrophication problems over the recent past. The severe environmental deterioration accompanied by cyanobacterial blooms have become major water resource management challenges in the region. An advanced research method is urgently needed to tackle these challenges. The concept of ecological resilience address pressing questions of non-linear dynamics, threshold effects and regime shifts in shallow floodplain lakes, and help manage the ecosystem effectively. Palaeolimnological techniques are important for assessing long term resilience and associated thresholds effects of shallow lake ecosystems. However, the lack of reliable proxy methods available, the assessment of long term ecological resilience of shallow Yangtze River lake systems has become increasingly difficult. Cladocerans (water fleas) play a central role in lacustrine food webs by responding to external drivers and internal ecosystem processes in lakes. Their subfossils are well preserved and becoming one of potential proxy indicators of lake ecosystems change for a longer time scale. This study explores the potential application of subfossil cladocerans and their ephippia in assessing a long term ecological resilience and help better management strategies of lake ecosystems and water resources of the middle and lower reaches of the Yangtze River in China. [ABSTRACT FROM AUTHOR]

In recent years, dramatic decline in China’s largest freshwater lake, Poyang Lake, has raised wide concerns about water supply and ecological crises in the middle–lower Yangtze River reaches. To assist in resolving the debates regarding the low water regime of the lake, the current study quantitatively assessed the enhanced water level decline from the changing underlying surface in the Poyang Lake region. It is the first time that the magnitude, temporal–spatial difference, trend development and background mechanism of lake water level variation and its causes are studied comprehensively. The results revealed that the changing underlying surface in the lake region has caused an average decline of annual water level of 0.26 m ~ 0.75 m across the lake during 2000–2014, which shows great seasonal and spatial differences. The enlarged outflow cross–section due to extensive sand mining was the major reason for the effect on water level decline in the northern lake. While, increased water surface gradient should be attributed to water level decline in the southern lake. The long–term increasing trend of annual lake water level decline reflects the cumulative effects of lake bottom topography change caused by the continuous south movement of sand mining activities. [ABSTRACT FROM AUTHOR]

The content levels, distribution characteristics, and health risks associated with 15 rare earth elements (REEs) in urban street dust from an industrial city, Zhuzhou, in central China were investigated. The total REE content (∑REE) ranged from 66.1 to 237.4 mg kg, with an average of 115.9 mg kg, which is lower than that of Chinese background soil and Yangtze river sediment. Average content of the individual REE in street dust decreased in the order Ce > La > Nd > Y > Pr > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The chondrite-normalized REE pattern indicated light REE (LREE) enrichment, a relatively steep LREE trend, heavy REE (HREE) depletion, a flat HREE trend, a Eu-negative anomaly and a Ce-positive anomaly. Foremost heavy local soil and to less degree anthropogenic pollution are the main sources of REE present in street dust. Health risk associated with the exposure of REE in street dust was assessed based on the carcinogenic and non-carcinogenic effect and lifetime average daily dose. The obtained cancer and non-cancer risk values prompt for no augmented health hazard. However, children had greater health risks than that of adults. [ABSTRACT FROM AUTHOR]

In this study, the summer rainfall patterns in the East China monsoon region during 1951-2015 were objectively classified into four typical categories: the northern China rainfall pattern (NCP), the intermediate rainfall pattern (IRP), the Yangtze River rainfall pattern (YRP), and the South China rainfall pattern (SCP). The periods of the four patterns show significant decadal characteristics. The NCP occurred mainly between the late 1950s and the early 1980s, and the IRP in the late 1950s to the early 1970s and the 2000s. The YRP occurred mainly between the 1980s and the 1990s, and the SCP between the mid-1990s and the early 21st century. The relationship between the East Asian summer monsoon index (EASM I ) and the four rainfall patterns was comparatively analyzed. The results confirmed that the four rainfall patterns have obvious differences in the EASM. In the NCP, IRP, or SCP years, the EASM I primarily showed a positive phase and a strong summer monsoon; in the YRP years, the EASM I primarily showed a negative phase and a weak summer monsoon. [ABSTRACT FROM AUTHOR]

In this study, we conducted investigations in the Changjiang (Yangtze) River estuary and adjacent waters (CREAW) in June and November of 2014. We collected water samples from different depths to analyze the nitrogen isotopic compositions of nitrate, nutrient concentrations (including inorganic N, P, and Si), and other physical and biological parameters, along with the vertical distribution and seasonal variations of these parameters. The compositions of nitrogen isotope in nitrate were measured with the denitrifier method. Results show that the Changjiang River diluted water (CDW) was the main factor affecting the shallow waters (above 10 m) of the CREAW, and CDW tended to influence the northern areas in June and the southern areas in November. $$\delta ^{15} N_{NO_3 } $$ values in CDW ranged from 3.21‰-3.55‰. In contrast, the deep waters (below 30 m) were affected by the subsurface water of the Kuroshio Current, which intruded into the waters near 31°N in June. The $$\delta ^{15} N_{NO_3 } $$ values of these waters were 6.03‰-7.6‰, slightly higher than the values of the Kuroshio Current. Nitrate assimilation by phytoplankton in the shallow waters of the study area varied seasonally. Because of the favorable temperature and nutrient conditions in June, abundant phytoplankton growth resulted in harmful algae blooms (HABs). Therefore, nitrate assimilation was strong in June and weak in November. The $$\delta ^{15} N_{NO_3 } $$ fractionations caused by assimilation of phytoplankton were 4.57‰ and 4.41‰ in the shallow waters in June and November, respectively. These results are consistent with previous laboratory cultures and in situ investigations. Nitrification processes were observed in some deep waters of the study area, and they were more apparent in November than in June. The fractionation values of nitrification ranged from 24‰-25‰, which agrees with results for Nitrosospira tenuis reported by previous studies. [ABSTRACT FROM AUTHOR]

The interaction between a river and the sea results in a turbidity maximum zone (TMZ) within the estuary, which has a great impact on the local ecosystem. In the Yangtze River Estuary, the magnitude and extent of the TMZ vary with water discharge. In this study, the cumulative human activity altered the water discharge regime from the river to the estuary. In the post-Three Gorges Dam (TGD) period, water discharge increased by 35.10 % at Datong in February compared with that in the pre-TGD period. The effects of water discharge variation on the characteristics of the TMZ were analyzed during spring and neap tidal periods using the three-dimensional environmental fluid dynamic code (EFDC) model. The area of the TMZ decreased by 3.11 and 17.39 % during neap and spring tides, respectively. In addition, the upper limit of the TMZ moved 11.68 km seaward during neap tide, whereas the upper limit of the TMZ in the upstream and downstream areas moved seaward 9.65 and 2.34 km, respectively, during spring tide. These findings suggest that the area and location of the TMZ are more sensitive to upstream runoff during spring tide than during neap tide. These changes in the TMZ will impact the biochemical processes in the Yangtze River Estuary. In the foreseeable future, the distribution characteristic of TMZ will inevitably change due to variations in the Yangtze River discharge resulting from new human activities (i.e., new dams), which are being constructed upstream in the Yangtze River system. [ABSTRACT FROM AUTHOR]

Based on daily precipitation data from 24 stations over the Yangtze River Delta (YRD) region, the long-term trends of daily precipitation are analyzed during the period 1960-2012 using 12 precipitation indices. The results indicate that the following. (1) For the regional average trends of precipitation, nine indices [i.e., RR, SDII, PCI(day), R25mm, R50mm, R25mmT, R50mmT, R25mmTOT, and R50mmTOT] show the increasing trends, while three indices [i.e., RX1day, RR1 and PCI(month)] display the decreasing trends. Furthermore, the annual total precipitation (RR) is correlated strongly with most of the other precipitation indices, especially indices represent the heavy precipitation which is responsible for more than 90 % of the total increase of precipitation. (2) The central and southern parts of the study area become more humid than the northern parts, although the daily precipitation undergo a consistent concentrated trend over almost all of the study area. Moreover, the frequency and contribution of the heavy precipitation also arise dramatically in almost the entire study area, and the precipitation events show the significant trend of extremeness. (3) The abrupt changes for RR, RX1day, SDII, R50mm, R50mmT, and R50mmTOT are detected in 1984, 1988, 1987, 1984, 1988, and 1988, respectively, which indicate the abrupt change of precipitation occurred consistently in the mid-1980s. Three major cycles of precipitation detected are 5-6-year cycle, 13-year cycle, and 20-year cycle, with a nonsignificant 2-year cycle coexisted. In addition, a significant change of cycles occurred in the 1980s, when the short cycle was set to overtake the long cycle, resulting in high-frequency and instability of precipitation changes over the YRD region in recent decades. (4) There are three factors (the global warming, the East Asian summer monsoon change, and the urbanization development) might potentially impact on the frequency and volume of precipitation. The variation of East Asian summer monsoon is the key factor that influences the increase of precipitation, while the global warming and the urbanization development perform the background factor and the local factor, respectively. [ABSTRACT FROM AUTHOR]

Lake eutrophication is harmful and difficult to predict due to its complex evolution. As an alternative to existing mechanistic models, a Markov chain model was developed to predict the development of lake eutrophication based on an 11-year dataset in 41 lakes of the Yangtze River Basin. This model was validated using a real-time update strategy and was demonstrated to be reliable. Based on the dataset, the lake eutrophication dynamics from 2000 to 2010 were analyzed. Lakes with different trophic states from 2011 to 2050 and their responses to different water management practices were simulated based on the developed model. The simulation results show that lake eutrophication would worsen from 2011 to 2040; however, eutrophication could be significantly alleviated by changing 100 km of hypereutrophic lakes into eutrophic lakes per year from 2010 to 2020. The nutrient conditions in most of the lakes in the Yangtze River Basin show that phosphorus control would be more efficient than nitrogen control in eutrophication management practices. This case study demonstrates the utility of Markov chain models in using prior information to predict the long-term evolution of lake eutrophication at large spatial scales. The Markov chain technique can be easily adapted to predict evolutionary processes in other disciplines. [ABSTRACT FROM AUTHOR]

Large areas of natural coastal wetlands have suffered severely from human-driven damages or conversions (e.g., land reclamations), but coastal carbon flux responses in reclaimed wetlands are largely unknown. The lack of knowledge of the environmental control mechanisms of carbon fluxes also limits the carbon budget management of reclaimed wetlands. The net ecosystem exchange (NEE) in a coastal wetland at Dongtan of Chongming Island in the Yangtze estuary was monitored throughout 2012 using the eddy covariance technique more than 14 years after this wetland was reclaimed using dykes to stop tidal flooding. The driving biophysical variables of NEE were also examined. The results showed that NEE displayed marked diurnal and seasonal variations. The monthly mean NEE showed that this ecosystem functioned as a CO sink during 9 months of the year, with a maximum value in September (−101.2 g C m) and a minimum value in November (−8.2 g C m). The annual CO balance of the reclaimed coastal wetland was −558.4 g C m year. The ratio of ecosystem respiration (ER) to gross primary production (GPP) was 0.57, which suggests that 57 % of the organic carbon assimilated by wetland plants was consumed by plant respiration and soil heterotrophic respiration. Stepwise multiple linear regressions suggested that temperature and photosynthetically active radiation (PAR) were the two dominant micrometeorological variables driving seasonal variations in NEE, while soil moisture ( M) and soil salinity (PS) played minor roles. For the entire year, PAR and daytime NEE were significantly correlated, as well as temperature and nighttime NEE. These nonlinear relationships varied seasonally: the maximum ecosystem photosynthetic rate ( A), apparent quantum yield (∂), and Q reached their peak values during summer (17.09 μmol CO m s), autumn (0.13 μmol CO μmol photon), and spring (2.16), respectively. Exceptionally high M or PS values indirectly restricted ecosystem CO fixation capacity by reducing the PAR sensitivity of the NEE. The leaf area index (LAI) and live aboveground biomass (AGB) were significantly correlated with NEE during the growing season. Although the annual net CO fixation rate of the coastal reclaimed wetland was distinctly lower than the unreclaimed coastal wetland in the same region, it was quite high relative to many inland freshwater wetlands and estuarine/coastal wetlands located at latitudes higher than this site. Thus, it is concluded that although the net CO fixation capacity of the coastal wetland was reduced by land reclamation, it can still perform as an important CO sink. [ABSTRACT FROM AUTHOR]

Landscape pattern plays an important role in structuring of larval fish assemblages in large river basins. The lower reach of the Yangtze River includes the river section from the mouth of Poyang Lake, the largest freshwater lake in China, downward to the estuary. We hypothesized that river-lake connectivity at the upstream portion and tidal intrusion at the downstream portion are significant drivers of larval fish assemblages. Larval fish were collected monthly from April 2012 through September 2013 in three locations at Anqing (AQ), Nanjing (NJ), and Jingjiang (JJ). Fifty-six taxa of larval fish were identified with 52 of them determined of species. Larval fish were highly abundant from April through August; the number of species and the abundance were much higher at AQ than at NJ and JJ; the bloom of larval fish at JJ tended to be later than at NJ and AQ. We suggest that the larger number of species and higher abundance of larval fish at AQ reflect the effects of the connectivity of Poyang Lake with the river upstream of AQ, and the delayed bloom of larval fish and the occurrence of estuarine species at JJ reflect the influences of tidal intrusion from the estuary. [ABSTRACT FROM AUTHOR]

In this study, positive matrix factorization (PMF) and principal components analysis (PCA) were combined to identify and apportion pollution-based sources of hazardous elements in the surface sediments in the Yangtze River estuary (YRE). Source identification analysis indicated that PC1, including Al, Fe, Mn, Cr, Ni, As, Cu, and Zn, can be defined as a sewage component; PC2, including Pb and Sb, can be considered as an atmospheric deposition component; and PC3, containing Cd and Hg, can be considered as an agricultural nonpoint component. To better identify the sources and quantitatively apportion the concentrations to their sources, eight sources were identified with PMF: agricultural/industrial sewage mixed (18.6 %), mining wastewater (15.9 %), agricultural fertilizer (14.5 %), atmospheric deposition (12.8 %), agricultural nonpoint (10.6 %), industrial wastewater (9.8 %), marine activity (9.0 %), and nickel plating industry (8.8 %). Overall, the hazardous element content seems to be more connected to anthropogenic activity instead of natural sources. The PCA results laid the foundation for the PMF analysis by providing a general classification of sources. PMF resolves more factors with a higher explained variance than PCA; PMF provided both the internal analysis and the quantitative analysis. The combination of the two methods can provide more reasonable and reliable results. [ABSTRACT FROM AUTHOR]

The vulnerability of major ecosystems to extreme rainfalls was investigated across the middle and lower reaches of the Yangtze River, China, during 1961-2000, by using an improved process-based model (Carbon Exchange between Vegetation, Soil, and Atmosphere, CEVSA). The simulated Net Primary Productivity (NPP) was selected as the indicator to identify impacts of extreme rainfalls on ecosystem functioning. The changing characteristics of the NPP in the five extreme rainfall years are employed to represent the sensitivity and adaptive capacity of ecosystems to extreme rainfalls events. The vulnerability of major ecosystems to extreme rainfalls was then examined by comparing with the averaged status during 1961-1990. Our results suggest that the relatively lower and higher vulnerable agro-ecosystems were mainly distributed in the central and northwest of the study area. The proportions of high and very high vulnerable agro-ecosystems to rainfall were about 19 and 5 % of the total area. For the forest ecosystem, the lower vulnerability mainly occurred in the south, while the higher vulnerability happened in the north of the study area which had taken about 15 % of the high vulnerable level and about 2 % of the very high vulnerable level. The extreme rainfalls enhanced the vulnerability both of agro-ecosystems and forest ecosystems. The vulnerability of agro-ecosystems to droughts was higher than that of forest ecosystems, while the vulnerability of forest ecosystems to floods was higher than that of agro-ecosystems. Our study demonstrates that both human-dominated (e.g., agro-ecosystem) and natural ecosystems are vulnerable to extreme climatic events. Future warming climate might further worsen the ecosystem sustainability in this area if no mitigation and adaptation measures are adopted. [ABSTRACT FROM AUTHOR]

Phosphorous (P) is an essential nutrient in soil which can lead to eutrophication when eroding into rivers or lakes. As a new method to represent soil properties, fractal theory was applied to study soil characteristics and related process. To understand the correlation of total soil P (TSP) and fractal dimension ( D) with the effect of soil depth and slope gradient, soil grid samples were collected at 0-10, 10-20 and 20-40 cm depths in Yingwugou watershed, Yangtze River, China. The physico-chemical properties of the samples were analyzed to determine the TSP content and D. Fractal scaling theory was then applied to establish the relationship between D and TSP. With silt as the dominant particle size, the D values of the study area were in the range of 2.42-2.55. On the flat ground, more fine particles (clay and silt) were reserved and on the contrary relatively high content of coarse sand was retained on steep slope. D values decreased with slope and soil depth increased. The average TSP contents of the three layers were 0.65, 0.63 and 0.57 g/kg for 0-10, 10-20 and 20-40 cm, respectively, showing a decreasing tendency with increased soil depth. With increasing slope gradient, the TSP contents decreased first and then increased slowly. The TSP contents were positively related to silt content ( P < 0.05) and clay content ( P < 0.05) and negatively associated with sand contents ( P < 0.01). There was an one-dimensional linear relationship ( n = 530, R = 0.16, P < 0.01) between TSP content and D values. The correlation would improve when concrete slope was taken into account. To better understand and control soil erosion, the relationship between D value and soil nutrients deserves more attention. [ABSTRACT FROM AUTHOR]

China's water source includes the headwaters of the Yangtze, Yellow, and Lantsang (the Mekong outside China) rivers and is located in the heart of the Tibet Plateau, which has an average altitude of 4,200 m. Due to the importance of the Water Tower to the ecological security and economic development of China and South Asia, desertification issues in this region have attracted the attention of the public, scholars, government officials, and international organizations. Combined satellite-derived vegetation indices, field surveys, and surface meteorological data to evaluate the effects of climate change, our analyzed results show that during the early part of the twenty-first century, no desertification occurred in these source areas. However, between 2000 and 2010, human activities may have had a negative effect on about 50 % of the region, although vegetation rehabilitation still occurred during this period. Although the Ecological Protection and Restoration Program was launched in China in 2005, the negative impacts of human activities such as agriculture have still increased in the water source. Vegetation rehabilitation in these source areas appears to be driven mainly by the effect of climate change, and it is possible that human activities do not play an important role in regional ecological and environmental evolution. Although at present we cannot determine whether it was rising temperatures or increasing precipitation that enhanced vegetation growth in the region, our results show that the dominant factors controlling vegetation rehabilitation in China's Water Tower are related to climate. [ABSTRACT FROM AUTHOR]