作者机构：
[Tang, Hui; Xiong, Yajun; Tian, Xiaobo] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Tang, Hui] Hunan City Univ, Sch Architecture & Urban Planning, Yiyang 413000, Peoples R China.
通讯机构：
[Xiaobo Tian; Hui Tang] A;Authors to whom correspondence should be addressed.<&wdkj&>School of Architecture and Urban Planning, Hunan City University, Yiyang 413000, China<&wdkj&>College of Urban and Environmental Science, Central China Normal University, Wuhan 430079, China<&wdkj&>Authors to whom correspondence should be addressed.<&wdkj&>College of Urban and Environmental Science, Central China Normal University, Wuhan 430079, China
关键词：
railroad urban network;resilience assessment;vulnerability analysis;interference resilience analysis;yellow river basin
摘要：
With the gradual networking of inter-city relations and the increase in acute impact and chronic stress, the measurement of the resilience of urban network structures is particularly prominent. Based on the construction of the urban network by passenger train trips in the Yellow River Basin, this paper analyzes and assesses the characteristics of the structural resilience of the urban network, and probes into the network resilience and urban response under the circumstances of node failure and line failure in Zhengzhou. The main conclusions are as follows: (1) The urban network in the Yellow River Basin was clearly hierarchical, with a significant spatial distribution of “low in the north and high in the south”, and the overall characteristics of “robustness” in small areas and “fragility” in large areas. The network connection forms were diversified and open. The network transmission efficiency was high, and the edge cities depended on the core cities with prominent characteristics, and the risk load of regional core cities rose. (2) The network structure was “robust” as it maintained high operational efficiency and connectivity under random attacks. Under deliberate attacks, the city network operated efficiently with a small increase in connectivity before the 60% threshold, and after the threshold, the overall network started to split into many sub-networks, and the network fragmentation gradually increased until the network collapsed. (3) Zhengzhou node failure and line failure states in the Yellow River Basin urban network were resilient, in the sense that when suffering important nodes and lines going down it could still maintain good network operation efficiency, and the core nodes in the impact of natural disasters could adapt to the destructive nature of the network through the urban network structure self-regulation.
关键词：
Water quality;Hydrological condition;Three gorges dam;Dongting lake
摘要：
Identifying the spatiotemporal characteristics of water quality and related driving factors is essential for lake water quality management. To further understand the unique relationship between hydrological conditions and water quality in river-connected lakes, we analysed the spatiotemporal variations of water quality and hydrological factors in Dongting Lake from 1991 to 2018 and identified the effects of the operation of the Three Gorges Dam (TGD) on lake water quality. The total nitrogen (TN) and total phosphorus (TP) concentrations showed general increasing trends in the pre-TGD period, in contrast to a significant increasing TN trend and a decreasing TP trend in the post-TGD period, the latter of which was closely linked to a prominent decrease of water and suspended sediment discharge after the initiation of TGD operation. TN concentrations showed significant spatial variations during the study period, with the highest concentration in East Dongting Lake and the lowest concentration in West Dongting Lake. Nutrient inputs were the dominant pollution source determining the water quality of Dongting Lake; water discharge and water level were also important factors controlling the spatiotemporal variability of water quality. The contribution of the four tributaries to lake water quality was much greater than that of the three channels, accounting for 89.94-92.25% of N inputs and 74.10-75.85% of P inputs. Moreover, the contribution of the three channels to lake water quality decreased after TGD operation, mainly because of reduced nutrient input, water discharge, and suspended sediment discharge. This study indicates that controlling pollutant effluents in tributaries and monitoring hydrological conditions within the lake are the key factors necessary to improve the water quality in Dongting Lake and may provide a practical reference for water quality management in river-connected lakes worldwide. (C) 2020 Elsevier Ltd. All rights reserved.
期刊：
ISPRS International Journal of Geo-Information,2021年10(7):466- ISSN：2220-9964
通讯作者：
Nan Yang
作者机构：
[Zhao, Yunlin; Xu, Zhenggang; Mo, Wenbo] Cent South Univ Forestry & Technol, Key Lab Forestry Remote Sensing Based Big Data &, Changsha 410004, Peoples R China.;[Mo, Wenbo] Hunan City Univ Design & Res Inst Co LTD, Changsha 410028, Peoples R China.;[Mo, Wenbo] Hunan Urban & Rural Ecol Planning & Restorat Engn, Changsha 410028, Peoples R China.;[Yang, Nan] Hunan City Univ, Coll Architecture & Urban Planning, Lab Key Technol Digital Urban Rural Spatial Plann, Yiyang 413000, Peoples R China.;[Zhao, Weiping] Hunan Agr Univ, Sch Business, Changsha 410128, Peoples R China.
通讯机构：
[Nan Yang] L;Laboratory of Key Technologies of Digital Urban-Rural Spatial Planning of Hunan Province, College of Architecture & Urban Planning, Hunan City University, Yiyang 413000, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
water yield services;InVEST;land use;land cover;Dongjiang Lake Basin
摘要：
Spatial and quantitative assessments of water yield services in watershed ecosystems are necessary for water resource management and improved water ecological protection. In this study, we used the InVEST model to estimate regional water yield in the Dongjiang Lake Basin in China. Moreover, we designed six scenarios to explore the impacts of climate and land use/land cover (LULC) changes on regional water yield and quantitatively determined the dominant mechanisms of water yield services. The results are expected to provide an important theoretical reference for future spatial planning and improvements of ecological service functions at the water source site. We found that (1) under the time series analysis, the water yield changes of the Dongjiang Lake Basin showed an initial decrease followed by an increase. Spatially, water yield also decreased from the lake area to the surrounding region. (2) Climate change exerted a more significant impact on water yield changes, contributing more than 98.26% to the water yield variability in the basin. In contrast, LULC had a much smaller influence, contributing only 1.74 %. (3) The spatial distribution pattern of water yield services in the watershed was more vulnerable to LULC changes. In particular, the expansion of built-up land is expected to increase the depth of regional water yield and alter its distribution, but it also increases the risk of waterlogging. Therefore, future development in the basin must consider the protection of ecological spaces and maintain the stability of the regional water yield function.
作者机构：
[Wang, Qing] Beijing Radiat Ctr, Key Lab Beam Technol, Minist Educ, 12 Xueyuannan Rd, Beijing 100875, Peoples R China.;[Li, Yan] Liaoning Normal Univ, Sch Life Sci, South Liushu St 1, Dalian 116081, Liaoning, Peoples R China.;[Ferguson, David K.] Univ Vienna, Dept Palaeontol, Althanstr 14, A-1090 Vienna, Austria.;[Mo, Wen-Bo] Cent South Univ Forestry Sci & Technol, Coll Life Sci & Technol, Changsha 410004, Hunan, Peoples R China.;[Yang, Nan] Hunan City Univ, Coll Architecture & Urban Planning, Lab Key Technol Digital Urban Rural Spatial Plann, Yiyang 413000, Hunan, Peoples R China.
通讯机构：
[Wang, Q.] T;[Li, Y.] S;School of Life Science, South Liushu Street 1, China;The Key Laboratory of Beam Technology of Ministry of Education, 12 Xueyuannan Road, China
关键词：
Asian Monsoon;Climate evolution;Climate gradients;Co-existence approach;The Tibetan Plateau
摘要：
Many studies have suggested that the climate diversified in China during the Miocene, with the emergence of an arid region in north-western China, as the Asian Monsoon intensified with the rapid uplift of the Tibetan Plateau in the late Miocene. However, this opinion is not upheld by all geoscientists. Here Miocene fossil plant assemblages from 75 broadly scattered sites across China were investigated with the Co-existence Approach (CA) to exhibit trends in temperature and precipitation in time and space. Modern distributions and recorded climate data from China regarding the nearest living relatives of the fossil plant taxa were employed to pin-point the climatic parameters in which a maximum number of taxa could coexist. Evolution and climatic trends are presented in maps of China from the early, middle to late Miocene. These maps illustrate that the ranges of the temperature and precipitation in the Miocene were similar to or just a little larger than those in the Eocene but much smaller than those of the present. The whole of China still had low latitudinal climate gradients and was characterized by a subtropical climate without any arid region. The changing contours of temperature and precipitation may be ascribed to the initial stage of the Asian Monsoon. There was no abrupt elevation of the Tibetan Plateau, nor had the Plateau attained its present altitude or orography in the Miocene.
作者机构：
[Chen, Xinsheng; Geng, Mingming; Deng, Zhengmiao; Zou, Yeai; Li, Feng; Wang, Kelin; Xie, Yonghong] Chinese Acad Sci, Inst Subtrop Agr, Key Lab Agroecol Proc Subtrop Reg, Changsha 410125, Hunan, Peoples R China.;[Chen, Xinsheng; Geng, Mingming; Deng, Zhengmiao; Zou, Yeai; Li, Feng; Xie, Yonghong] Chinese Acad Sci, Inst Subtrop Agr, Dongting Lake Stn Wetland Ecosyst Res, Changsha 410125, Hunan, Peoples R China.;[Geng, Mingming] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;[Yang, Nan] Hunan City Univ, Coll Architecture & Urban Planning, Key Lab Key Technol Digital Urban Rural Spatial P, Yiyang 413000, Hunan, Peoples R China.;[Qian, Zhan] Hunan Hydro & Power Design Inst, Dongting Lake Res Ctr, Changsha 410007, Hunan, Peoples R China.
通讯机构：
[Feng Li] K;Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China<&wdkj&>Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China
关键词：
Mining and manufacturing;Rock weathering;Fertilizer and pesticide use;Principal component analysis;Mixed metal pollution;Surface water pollution
摘要：
This study collected past sampling data on total concentrations of 12 heavy metals (Cd, Pb, Cr, Hg, Zn, Cu, Ni, Al, Fe, Mn, As, and Co) in surface water bodies, i.e., 168 rivers and 71 lakes, from 1972 to 2017. The intent was to investigate the levels and sources of heavy metal pollution across five decades and five continents. Mean heavy metal concentrations in global river and lake water, and the number of heavy metals with concentrations greater than the published threshold limits as per the standards of both the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA) were generally lower in the 1970s and 1980s than in the 1990s, 2000s, and 2010s. Over time, heavy metal pollution in surface water has changed from single metal pollution to mixed metal pollution. Heavy metal concentrations in water, and the number of heavy metals with concentrations above the threshold limits for both WHO and USEPA standards were lower in the developed countries of Europe and North America, and higher in the developing countries of Africa, Asia, and South America. Over time, the main sources of metal pollution have changed from mining and manufacturing to rock weathering and waste discharge. The main metal sources differed across the five continents, with fertilizer and pesticide use, along with rock weathering, being dominant in Africa. Mining and manufacturing, along with rock weathering, were dominant in Asia and Europe. Mining and manufacturing, along with fertilizer and pesticide use, were dominant sources in North America, while four sources (mining and manufacturing, fertilizer and pesticide use, rock weathering, and waste discharge) were responsible for the majority of heavy metal pollution in the river and lake water bodies of South America. Additionally, implementing rigorous standards on metal emissions and recycling metals from wastewater are effective for controlling heavy metal source pollution. (C) 2020 The Authors. Published by Elsevier B.V.
摘要：
Hydroponic experiments with different cadmium (Cd) concentrations were conducted to explore the impacts of nutrient allocation on the Cd enrichment of Bermuda grass. The results demonstrated with the Cd concentration increase, the accumulation of nitrogen (N), phosphorus (P) and potassium (K) in roots, stems and leaves increased first and then decreased, while the accumulation of Cd had no significant difference. The biomass and N, P and K accumulation of CD1 and CD2 were significantly different from those of CD3 and CD4, but there was no significant difference in Cd accumulation. The root N, P and K distribution ratio of CD4 increased by 47.9%, 114.3% and 64.3% compared with those of CD2 treatment, the values of stem decreased by 29.4%, 22.4% and 17.2%, and the values of leaves increased by 15.8%, 19.8% and 23.6% respectively. The K ratio of root and leaf increased and that of stem decreased. Cd reduced N and K distribution ratio of stem and increased N and K distribution ratio of root and leaf. Pearson correlation analysis showed that the accumulation of N, P and K in stems was positively correlated with the accumulation of Cd in stems, and the accumulation of N, P and K in roots, stems and leaves were positively correlated with the Cd accumulation in leaves. Bermuda grass can schedule the nutrient allocation to adapt to the Cd absorption and enrichment in different organs under different Cd concentrations. In conclusion, nutrient allocation might affect the Cd accumulation of Bermuda grass. (C) 2020 Elsevier Ltd. All rights reserved.
摘要：
With the acceleration of urbanization and industrialization, increasingly serious global climate change issues have profoundly affected the survival and development of human beings, and natural, ecological and social systems are facing unprecedented threats and challenges. The purpose of this article is to study urban planning from multiple perspectives and levels, and strive to create a healthy ecologically balanced environment. This article takes city A as the research object, and uses the theory of SD and low-carbon(LC) cities as a guide to analyze the social and economic development level, regional resources, and environment of city A, and compare it with representative cities. Through the analysis of decoupling index, the stage of LC development in city A was clarified, and the urbanization rate of city A was 68%. The economic growth of city A mainly depends on the rapid development of high-energy-consuming industries. We must adjust the economic structure. On the basis of full demonstration and analysis, development strategies are proposed from the aspects of urban planning, LC economy and LC transportation to promote the harmonious development of the ecological environment and the city. (C) 2020 Elsevier Inc. All rights reserved.
摘要：
High-resolution satellite technology is playing an increasingly important role in environmental monitoring. As the first high-resolution satellite for earth observation in China, GaoFen-1 (GF-1) has great potential for collecting water depth data. Multispectral images from GF-1 (16 m) combined with water depth data from long-term monitoring at a hydrological station were used with the normalized difference waterbody index, density segmentation, band combination, models (single-band, multi-band, and dual-band ratio) to invert the water depth of East Dongting Lake in the dry season and to provide important references for remote sensing of water depth. The experimental results are as follows. (1) Red, green, blue, and combined bands had higher correlation with the measured data. Consequently, the green band was chosen as the factor in the single-band model; blue, green, and red bands in the multi-band model and the ratio of green to red bands in the dual-band ratio model. (2) The correlation coefficients of measured data and single-, multi, and dual-band models were 0.848, 0.867, and 0.925, respectively. (3) The inversion results showed that average water level in East Dongting Lake was approximately 20 m in the dry season during the period 2013-2016 and it was highest in southern area, intermediate in eastern area, and lowest in the western area. (C) 2020 The Authors. Published by Elsevier B.V.
关键词：
Biogas slurry irrigation;Chinese cabbage;Nitrate and heavy metal residue;Nutrient and metal removal by microalgae;Nutritional quality
摘要：
Biogas slurry (BS) is a main byproduct of biogas production that is commonly used for agricultural irrigation because of its abundant nutrients and microelements. However, direct application of BS may cause quality decline and nitrate and heavy metal accumulation in crops. To address this issue, a microalgae culture experiment and an irrigation experiment were performed to evaluate the removal efficiencies of nutrients and heavy metals from diluted BS by microalgae Scenedesmus sp. and to investigate the effects of irrigation with microalgae-treated BS (MBS-25, MBS-50, MBS-75, and MBS-100) on nutritional quality, oxidation resistance, and nitrate and heavy metal residues in Chinese cabbage. After 8 days of continuous culture, a ratio of 1/1 for BS/tap water mixture (BS-50) was the optimal proportion for microalgal growth (3.73g dry cell L(-1)) and efficient removal of total nitrogen (86.1%), total phosphorus (94.3%), COD (87.5%), Cr (50%), Pb (60.7%), and Cd (59.7%). The pH in MBS-50 medium recovered to the highest level in a shorter period of time and accelerated the gas stripping of ammonia nitrogen and the formation of insoluble phosphate and metals, which partly contributed to the high removal efficiencies. MBS irrigation significantly promoted crop growth; improved nutritional quality, edible taste, and oxidation resistance; and reduced nitrate and heavy metal residues in Chinese cabbage at a large scale. Therefore, microalgae culture was beneficial to reduce negative impacts of BS irrigation in crop growth and agricultural product safety. This study may provide a theoretical basis for the safe utilization of BS waste in agricultural irrigation.
摘要：
The acute toxicity of divalent mercury ion to Anguilla japonica from seawater and freshwater aquaculture was assessed. In particular, the effects of toxicity on the microstructures of the gill and liver tissues were examined using the hydrostatic method, without feeding, at a water temperature of 20 °C. The median lethal concentrations (LC50) of divalent mercury ion to fishes in seawater and freshwater over various durations were: 24 h = 1.637 and 1.428 mg/L; 48 h = 1.562 and 1.377 mg/L; 72 h = 1.530 and 1.284 mg/L; and 96 h = 1.442 and 1.228 mg/L. The safety mass concentrations were 0.1442 and 0.01228 mg/L, respectively. After exposure to divalent mercury ion, adhesion between the gill lamellae and massive cellular disintegration and necrotic shedding were observed in the gill tissue sections. The liver tissues underwent hyperemia and swelling, with the appearance of blood spots, swelling of the hepatocyte mitochondria, dilation of the rough endoplasmic reticulum, and intercellular inflation.
