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.
关键词：
Land use allocation;Multi-objective optimization;Multi-agent system;Sustainable land use;China
摘要：
Achieving multi-objective land use optimization allocation (MOLUOA) for sustainable development is an important issue in land use. In consideration of the multi-dimensional characteristics of MOLUOA in terms of quantity, space, and time, and under the constraints of maximizing economic, ecological, and social benefits of land use, a MOLUOA model is developed in this study by integrating multi-agent system with particle swarm optimization. The MOLUOA model is applied to the simulation of land use optimization allocation in Changsha, a typical city located in central China. Simulation results show that the MOLUOA model can achieve multi-objective land use optimization allocation in terms of quantity, space, and time. The model can provide decision-making support for generating land use alternatives to achieve sustainable land use. (C) 2015 Elsevier B.V. All rights reserved.
关键词：
Water quality;Hydrological conditions;Self-organising map;Three Gorges Dam;Dongting Lake
摘要：
Lake water pollution has caused many serious ecological issues globally. An emerging public concern over water quality deterioration in lakes has heightened the need to evaluate the water quality of lakes at long-term scales, particularly for those with high hydrological alterations. This study combines the Mann -Kendall (M-K) test and self-organising map (SOM) to characterise and evaluate water quality trends in Dongting Lake, China, from 1991 to 2018, before and after the inauguration of the Three Gorges Dam (TGD). Herein, six water quality parameters were selected, namely pH, permanganate index (CODMn), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphorus (TP), and the five-day biochemical oxygen demand (BOD5). Our results show that the concentrations of TN and BOD5 increase significantly throughout the study period (vertical bar Z vertical bar >= 1.96). The number of abrupt change points for the six water quality parameters in the post-TGD period was greater than that in the pre-TGD period, which indicates an increased risk of water deterioration in the post-TGD period. The SOM results show that the pH values ranged from 7.64 to 7.85 among the four clusters; besides, the concentrations of the remaining water quality parameters from 1991 to 1997 and 2000 to 2003 were relatively lower, suggesting that the water quality in the pre-TGD period was better. The classification of TN and TP ranged from Level IV V among the clusters, which did not satisfy the level III standard for potable water, thereby posing a higher ecological risk to the Dongting Lake. These results indicate the deterioration of the water quality in Dongting Lake during the post-TGD period under the influences of pollution load and hydrological regulation. Therefore, strict controls on the external nutrient loading and hydrological regulations should be considered for water quality management. (C) 2020 Elsevier Ltd. All rights reserved.
摘要：
Due to its great strategic significance in integrating regional coordinated development and enhancing the rise of Central China, urban agglomeration in the middle reaches of Changjiang (Yangtze) River has attracted much attention from both theoretical and practical aspects. Such research into the area’s economic network structure is beneficial for the formation of an urban- and regional-development strategy. This paper constructs an economic tie model based on a modified gravitation model. Subsequently, referring to social network analysis, the paper empirically studies the network density, network centrality, subgroups and structural holes of the middle reaches of Changjiang River’s urban agglomeration economic network. The findings are fourfold: (1) an economic network of urban agglomeration in the middle reaches of Changjiang River has been formed, and economic ties between the cities in this network are comparatively dense; (2) the urban agglomeration in the middle reaches of Changjiang River can be divided into four significant subgroups, with each subgroup having its own obvious economic communications, while there is less economic-behavioral heterogeneity among subgroups — this is especially true for the two subgroups that exist in the Poyang Lake Ecological Economic Zone; (3) an economy pattern driven by the central cities of Wuhan, Changsha and Nanchang has emerged in the urban agglomeration of the middle reaches of Changjiang River, while these three capital cities have exerted great radiation abilities to their surrounding cities, the latter are less able to absorb resources from the former; (4) the Wuhan Metropolitan Areas and the Poyang Lake Ecological Economic Zone have more structural holes than the Ring of Changsha, Zhuzhou and the Xiangtan City Clusters, meaning that cities at the periphery of these two areas are easily constrained by central cities. The Ring of Changsha, Zhuzhou and the Xiangtan City Clusters have fewer structural holes; thus, the cities in this area will not face as many constraints as those in the other two areas.
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.
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：
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.
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：
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.
期刊：
Environmental Science and Pollution Research,2021年29(10):14083-14097 ISSN：0944-1344
通讯作者：
Li, Feng
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, 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, Peoples R China.;[Geng, Mingming] Univ Chinese Acad Sci, Beijing 100049, Peoples R China.;[Niu, Yandong] Hunan Acad Forestry, Changsha 410004, Peoples R China.;[Qian, Zhan; Liao, Xiaohong] Hunan Hydro & Power Design Inst, Dongting Lake Res Ctr, Changsha 410007, Peoples R China.
通讯机构：
[Li, Feng] K;Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, People's Republic of China.;Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, People's Republic of China.
摘要：
The hydrological conditions of river-connected lakes are complex primarily owing to their considerable water-level fluctuations (WLFs). Water quality in such lakes varies with hydrodynamic variations; however, their relationship is not clear. To identify the unique relationship between water level and water quality in river-connected lakes, we used the comprehensive pollution index (CPI) and regression analysis to analyze the spatiotemporal variation in water quality in Dongting Lake from 2015 to 2018 and the effects of water level on water quality. Four water quality parameters were selected: total nitrogen (TN), total phosphorus (TP), permanganate index (COD(Mn)), and chlorophyll a (Chl-a). The results showed significant spatial variation in the lake water quality, with relatively high concentrations of TN, TP, COD(Mn), and Chl-a in East Dongting Lake. TN and TP decreased by 12.15% and 37.61%, respectively, from 2015 to 2018, whereas COD(Mn) increased from 1.781 to 2.009 mg/L. Seasonally, TN and TP concentrations were low in the summer and autumn, with high concentrations in the winter and spring. In contrast, COD(Mn) and Chl-a concentrations exhibited opposite trends. The pollution level in Dongting Lake ranged between slightly and moderately polluted, with a CPI ranging from 0.76 to 1.32 across all sampling sites during 2015-2018. The water level in Dongting Lake initially increased and, then, decreased in a year, with marked WLFs owing to seasonal shifts in precipitation and human activities. The water level had significant negative relationships with TN and TP concentrations and a significant positive relationship with COD(Mn) concentration (p < 0.05). Based on the results, strict control of excessive external nutrient loading should be actively implemented in Dongting Lake, in addition to hydrological regulation for effective lake water quality management.
期刊：
ISPRS International Journal of Geo-Information,2021年10(7):466 ISSN：2220-9964
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.
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.
