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The Huayuankou flood event (1938–1947) refers to the prolonged flooding caused by the artificial bursting of the Yellow River embankment at Huayuankou during the Sino-Japanese War (1937–1945). It recreated the historical scenes of frequent floods in the lower Yellow River region of China since the Ming and Qing Dynasties (1368–1911), with the counties along the Jialu River in the eastern plains of Henan especially becoming the disaster-stricken areas. The flood lasted for nearly nine years until the completion of embankment restoration work in 1947, causing long-term and extensive environmental impacts. This paper discusses this catastrophic historical flood event caused by human factors, the warfare strategies and hydraulic technology that acted as drives, and the location factors and historical context leading to the start of flooding in flood-prone areas of Henan. Based on spatial perspectives and the historical GIS approach, the paper compiles and integrates historical documents and maps with archival material and topographic maps from the 1930s and 1940s to present the extent of the flood, the associated disasters, and the persistent effects of official relief strategies and political situation in the wider context, examining how the Huayuankou flood was used as a military tactic, but with unpredictable disastrous consequences. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) and microbes are key in the planetary carbon cycle, and research on them can lead to a better understanding of the global carbon cycle and an improved ability to cope with environmental challenges. Several papers have reviewed one or several aspects of the interaction of DOM and microbes, but no overall review has been performed. Here, we bibliometrically analyzed all publications from the Web of Science on DOM and microbes (1991–2020). The results showed that studies on DOM and microbes grew exponentially during this period; the USA contributed the most to the total publications, and China has had the fastest increasing rate since 2010. Moreover, we used the Latent Dirichlet Allocation model to identify topics and determine their (cold or hot) trends by analyzing the abstracts of 9851 publications related to DOM and microbes. A total of 96 topics were extracted, and these topics that are related to the source, composition, and removal path of DOM and the temporal-spatial patterns of DOM and microbes consistently rose from 1991 to 2020. Most studies have used accurate and rapid methods combined with microbiological genetic approaches to study the interaction of DOM and microbes in terrestrial and aquatic ecosystems. The results also showed that the impacts of climate change and land use on the interaction of DOM and microbes, and topics related to human health have received considerable attention. In the future, the interaction mechanism of DOM and microbes and its response to environmental change should be further elucidated. [ABSTRACT FROM AUTHOR]

Figuring out the impacts of future urbanization on hydrological response is significant in a rapidly changing environment. As an important urbanization element, the various impacts of land use/land cover change have been studied a lot with the methods of combining different land use scenarios and hydrological models. However, it needs to be improved because of only simplified land use scenarios being considered, which cannot reflect the real urbanization process of the future. Taking into account the roles of social and economic development, in this paper, a hybrid FLUS-SWAT method is proposed for the first time for accurately evaluating the hydrological responses to urbanization. First, instead of subjective assumption, future land use patterns are predicted by developing improved cellular automata model on driving forces involving regional population, gross domestic product, location, transportation network, etc. Then, spatial hydrological responses were individually analyzed by coupling projected future land use scenarios and distributed hydrological model. The results clearly forecasted a burst of urban expansion in future 100 years in Zhexi river basin, China. Loss of forest and agriculture land will lead to a 64.86% increase in surface runoff and 9.05% decrease in groundwater flow. This study is significant for ecological environment planning because it provides a direct understanding of future urbanization level as well as its impacts on hydrological processes. [ABSTRACT FROM AUTHOR]

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

The Carnian Pluvial Event (CPE) induced an intense carbon-cycle disturbance and biological crisis at a global scale. The eruption of the Wrangellia Large Igneous Province (W-LIP) is considered a possible triggering mechanism; however, this cannot fully explain the significant differences in environmental perturbations across different regions. In this paper, we present detailed records of petrography, mercury geochemistry, carbon and sulfur isotopes, trace elements, and provenance data for the Triassic lacustrine facies of the Ordos Basin in the North China Plate, which provide insights into the important effects of volcanic activities, other than the W-LIP, on palaeoenvironment during the CPE interval. Massive emissions of SO 2 , CO 2 , and pyroclastic deposits resulting from these volcanic activities triggered four humid episodes, each characterized by lake-level rise, negative δ13C org excursion, a transition from mudstones to organic-rich shales facies, as well as algal bloom within a time span of 180 kyrs. The establishment of an age framework in the Ordos Basin enables comparative analyses of environmental evolution during the Carnian age across the North China Plate, the western Tethys domain, and the South China Plate. During the period of global climate perturbation driven by the W-LIP eruption, we conclude that short-term localized volcanic activities may have further induced high frequentcy environmental perturbations, which influenced biological shifts and increase organic carbon burial. These short-term volcanic activities with different occurrence times and frequencies complicate local-scale palaeoenvironmental evolutions, which may be an important reason contributing to significant differences in environmental perturbations during the CPE interval across different regions of the globe. • Four humid episodes and sedimentary changes occurred within 0.18Ma in the Ordos Basin during Carnian age. • Environmental changes in the Ordos Basin was related to the local volcanisms in its nearby Qinling orogenic belts. • Short-term local volcanisms can complicate the environmental evolutions in different parts of globe during the CPE interval. • Local volcanic processes may cause inconsistent environment perturbation in different parts of globe during the CPE interval. [ABSTRACT FROM AUTHOR]

There is increasing interest in the application of digital soil mapping (DSM) projections to infer changes in soil carbon across both space and time. This approach relies on the assumption that the spatially modeled soil carbon-environment relationship can be transferred over time. However, this assumption is rarely tested due to a lack of temporally independent validation data. This paper assesses this assumption by developing models of topsoil organic carbon stocks (SOCS) with a deep learning algorithm and data covering mainland China pertaining to the 1980s and 2010s. The temporal prediction performance of models capturing a specific period was assessed by evaluating their performance in the prediction of data during another period. The results revealed that the prediction accuracy of temporal modeling decreased, as indicated by the coefficient of determination, and was lower than that of spatial modeling. The lower prediction accuracy obtained with the DSM-projection approach may result from differences in the magnitudes of influential variables across periods. We found that different levels of environmental similarity and model projection sensitivity to dynamic variables may cause discrepancies in forecast and hindcast accuracy. Our results demonstrate that the prediction error in temporal modeling is related to the degree of environmental similarity between periods. Our findings generally support the implementation of the DSM-projection approach in soil carbon change modeling. However, caution should be exercised, as there exists much uncertainty regarding the projection of spatial models over time. • DSM projection may facilitate a more precise estimation of large-scale soil carbon changes. • Discrepancies in the environment between periods reduce the temporal predictive skill. • The variability in the model performance is related to the magnitude of environmental influences. [ABSTRACT FROM AUTHOR]

Globally, climate change impacts on marine ecosystems are evident in physical, chemical, and biological processes, and are generally more extensive in faster warming regions. China makes the largest contribution of any country to global fisheries production and has experienced severe declines in marine health and biodiversity, and so the current and potential impacts of marine climate change are a large concern for both fisheries and biodiversity. China also has marine regions warming in the top 10% globally, necessitating a thorough understanding of how marine systems are changing so that appropriate corresponding countermeasures can be identified and prioritized. Here, we review and collate what is currently understood about documented and projected responses of marine systems to climate change in Chinese coasts and oceans, from physical, biological, and ecological perspectives, through to impacts on key ecosystems. Our results show extensive change attributed to climate change throughout Chinese marine systems, including red tide bloom events that have been recorded an order of magnitude more frequently in recent decades. Ocean acidification has led to the increased mortality of marine calcifying organisms through effects on the biomineralization process and physiological functions. Moreover, many species have been documented undergoing extensive changes in geographic distribution, with potential implications for species interactions and trophic food webs, as well as important habitats like coral reefs, seagrass, and mangroves. Some constructive laws and actions have been introduced in response to these climate-driven changes, such as actions to reduce pollution and increase artificial propagation and replanting of habitat species, however, addressing the impacts of marine climate change remains a considerable and escalating challenge. [ABSTRACT FROM AUTHOR]

The middle–late Cambrian is a key interval between the Cambrian Explosion and the Great Ordovician Biodiversification Event (GOBE) that marks a major biologic evolutionary transition in the geologic record. Diversity (i.e. richness) patterns in this interval show that macro-biota experienced evolutionary setbacks for the first time. However, relatively little attention has been paid to this interval in previous macroevolutionary studies and very different conclusions about the diversity patterns in coarse time-resolution have been documented. As a dominate group of marine benthic organisms in the Cambrian, trilobites provide insightful information to understand the history of biodiversity in the Cambrian marine ecosystem from the Cambrian Explosion to the GOBE. South China is a region with relatively good preservation of Cambrian fossil materials and sections, and 4 out of 6 Cambrian GSSPs were established in South China. In this paper, we use constrained optimization (CONOP) to correlate 19 sections from South China to reduce the Signor-Lipps effect and integrate the results with high-resolution chronostratigraphic data to evaluate the middle–late Cambrian trilobite diversity pattern in South China. This study, for the first time, constructs a high time-resolution (about 60 kyr) trilobite species-level richness curve with estimated time from Age 4 to the Paibian. A double-peaked species diversification is separated by a minor extinction in Stage 4; this is followed by a gradual decline of species diversity over the entire Wuliuan Age. A radiation of three times increase of species diversity in the Drumian and Guzhangian is exhibited and the diversity remains high for most of the Guzhangian Stage; this is followed by a great extinction at the end of the Guzhangian with around 50% species lost. Detailed comparison with previous composite studies and fossil material from single sections revealed that the Signor-Lipps effect could produce large biases in diversity pattern. In addition, a precise analysis of species evolution features compared with environmental indices provides a perspective about trilobite evolutionary mechanisms associated with environmental changes related to the carbon cycle and biotic competition. • Middle-late Cambrian trilobite diversity trajectory of South China is established. • High temporal resolution of diversity pattern is produced with CONOP method. • The results reveal two major diversity losses and a biodiversification event in Guzhuangian. • Signor-Lipps effect may affect diversity pattern significantly. • Major extinctions of trilobites are correlative with carbon isotope excursions. [ABSTRACT FROM AUTHOR]

Dramatic environmental changes and species invasions are increasingly threatening the diverse fish fauna of the Yellow River, China. This study examines temporal changes in the alpha and beta components of fish taxonomic, functional and phylogenetic diversity in relation to anthropogenic environmental changes over the past 50 years. We hypothesized that temporal trends in multifaceted components of diversity would be highly congruent, but that the relative importance of anthropogenic disturbances would differ in shaping spatial patterns of fish diversity. We found that all three components of alpha diversity increased over time but at different rates (19.1%, 21.3% and 15.3% for taxonomic, functional and phylogenetic diversity, respectively). Fish faunas of the Yellow River have also become homogenized over time, but this was much greater for functional and phylogenetic components of beta diversity than for taxonomic diversity (change in beta diversity = − 0.11, − 0.24 and − 0.02, respectively). Temporal changes in alpha and beta diversity were strongly related to invasion of non-native fish species and changes in temperature, sediment load, reservoir capacity and aquaculture area. Our results underscore the ongoing need for threat mitigation (particularly relating to dams and aquaculture) to conserve the unique biodiversity of one of the world's largest rivers. [ABSTRACT FROM AUTHOR]

In light of the rapid urbanization of the world's population over the past decades, there is a growing concern about the environmental impacts of urban population growth. Rural-urban migration is a particularly important component of the urbanization process in developing countries and is often considered to be detrimental to urban environmental conditions. However, few studies have explicitly examined the presumed negative impacts of in-migration on the natural environment of cities. The continuously increasing volume of rural-urban labor migration in China since the early 1980s has formed the largest population flow in world history. This study links the existing literature on population-environment and urbanization-environment interactions by empirically assessing the relationship between rural-urban migration and urban air conditions in China. A two-period (2004 and 2010) longitudinal dataset for the 113 key environmental protection cities of China was constructed based on multiple data sources. We applied the STIRPAT equation using conventional and spatial panel regression models to examine whether rural-urban migration flows were associated with air pollution in cities. Results show a strong negative association of in-migration with urban air quality even after controlling for the effects of other population, affluence, and technology factors. Findings from this research can contribute to a better understanding of the environmental consequences of rural-urban migration in China, with broader implications for sustainable development research and policies. [ABSTRACT FROM AUTHOR]

Lake Chenpu is located in the western part of Hetao Basin approaching the Ulan Buh Desert in the upper reaches of the Yellow River in northern China. An 84 cm sediment core was collected from the center of the lake. Geochronology radiometric method using Pb was subsequently used to date the short sediment core in the hope that it would reflect environmental changes over the past 150 years. Principal component analysis and the variation of the grain-size standard deviation were used to identify latent factors and extract environmentally sensitive grain-size components in sediment. Then a combination of sensitive grain-size parameters, magnetic susceptibility, total organic matter (TOC), and total nitrogen (TN) was used to reconstruct the recent lake environmental sequence. The result showed that the lake has seen increasing salinization and swampiness over the past 150 years. Further, sensitive grain-size parameters displayed several abrupt environment changes, i.e. 1850 AD, 1920 AD, and 1980 AD, which are supported by written records. In the 1850s, the yellow clay content increased dramatically, and that of silt declined. Magnetic susceptibility and C/N values increased significantly, as indicated by flood action. In the 1920s and the 1980s, dust-sand activity was recorded twice in the lake sediments with a markedly higher value of 16-32 μm and average grain size (C2). Grain size and other environmental proxies showed the period after the mid-1990s to be mainly dominated by wind-sand activity and anthropogenic impacts, which marked by obviously increasing grain-size coarse, carbonate content, TOC, and TN values. The results show that the lake sediments provide a dependable archive for studying the environmental history of the lake. [ABSTRACT FROM AUTHOR]