Research progress on ecological models in the field of water eutrophication: CiteSpace analysis based on data from the ISI web of science database

Trends in phytoremediation of heavy metals-contaminated soils: A Web of science and CiteSpace bibliometric analysis

Heavy metals pollution in soils is an urgent environmental issue worldwide. Phytoremediation is a green and eco-friendly way of remediating heavy metals. However, a systematic overview of this field is limited, and little is known about future development trends. Therefore, we used CiteSpace software to conduct bibliometric and visual analyses of published literature in the field of phytoremediation of heavy metals in soils from the Web of Science core collection and identified research hotspots and development trends in this field. Researchers are paying increased attention to phytoremediation of heavy metals in soils, especially environmental researchers. A total of 121 countries or regions, 3790 institutions, 4091 funded organisations and 15,482 authors have participated in research in this area. China, India, and Pakistan are the largest contributors. There has been extensive cooperation between countries, institutions, and authors worldwide, but there is a lack of cooperation among top authors. 'Calcareous soil', 'Co-contaminated soil' and 'Metal availability' are the most intensively investigated topics. 'EDTA', 'Plant growth-promoting Rhizobacteria', 'Photosynthesis', 'Biochar' and 'Phytoextraction' are research hotspots in this field. In addition, more and more researchers are beginning to pay attention to research on co-contaminated soil, metal availability, chelating agents, and microbial-assisted phytoremediation. In summary, bibliometric, and visual analyses in the field of phytoremediation of heavy metals in soils identifies probable directions for future research and provides a resource through which to better understand this rapidly advancing subject.

Bibliometric review of carbon peak with CiteSpace: evolution, trends, and framework

In the context of global climate change, countries around the world are actively implementing carbon peak and carbon neutrality goals. In-depth research on carbon peak can help improve environmental conditions and achieve a harmonious coexistence between economic development and environmental protection. However, a comprehensive review of the current status of research in this area is scarce. Therefore, this article explores the current research evolution and hotspots of "carbon peak" with the help of CiteSpace visualization software, predicts the future development trends, and builds a knowledge network framework. A comprehensive analysis of the research on carbon peak from multiple perspectives is presented. The results show that the number of papers published on carbon peak is increasing every year, and that carbon peak has become a widely participated research area. Publications from various institutions and journals have also attracted widespread attention. The research hotspots of carbon peak have constantly changed with time, resulting in many theoretical and technological innovations. The knowledge framework of the field is constructed on this basis, which gives readers a clearer understanding of the development and trends in the field and provides some reference and help for future researchers.

Farmland phytoremediation in bibliometric analysis

Phytoremediation is an environmentally friendly, economical, and sustainable technique for restoring farmland. It can remove heavy metals and organic pollutants from the soil through the implementation of hyperaccumulator plants. In recent years, it has garnered significant interest from academic and industrial sectors. This article screened 368 research papers from the Web of Science core collection database related to farmland phytoremediation and conducted a bibliometric analysis of the domain based on CiteSpace. The paper intuitively demonstrates the most influential countries, the most productive institutions, the most contributing groups of authors, and the primary sources of farmland phytoremediation research domain. The findings additionally indicate that the research hotspots include: (1) mechanisms and principles of phytoremediation, (2) the improvement of restoration efficiency, (3) the economic, ecological, and sustainable development of phytoremediation. The exploration of plants with potential to accumulate heavy metals and produce large amounts of biomass is the research frontier within the field of farmland phytoremediation. Additionally, this bibliometric analysis can help scholars willing to work in this research field by concisely understanding the overall research field and frontiers. With the continuous improvement of phytoremediation and its combination with other remediation technologies, the future of farmland remediation will have a promising prospect.

A bibliometric study on carbon cycling in vegetated blue carbon ecosystems

Understanding carbon cycling in blue carbon ecosystems is key to sequestrating more carbon in these ecosystems to mitigate climate change. However, limited information is available on the basic characteristics of publications, research hotspots, research frontiers, and the evolution of topics related to carbon cycling in different blue carbon ecosystems. Here, we conducted bibliometric analysis on carbon cycling in salt marsh, mangrove, and seagrass ecosystems. The results showed that interest in this field has dramatically increased with time, particularly for mangroves. The USA has substantially contributed to the research on all ecosystems. Research hotspots for salt marshes were sedimentation process, carbon sequestration, carbon emissions, lateral carbon exchange, litter decomposition, plant carbon fixation, and carbon sources. In addition, biomass estimation by allometric equations was a hotspot for mangroves, and carbonate cycling and ocean acidification were hotspots for seagrasses. Topics involving energy flow, such as productivity, food webs, and decomposition, were the predominant areas a decade ago. Current research frontiers mainly concentrated on climate change and carbon sequestration for all ecosystems, while methane emission was a common frontier for mangroves and salt marshes. Ecosystem-specific research frontiers included mangrove encroachment for salt marshes, ocean acidification for seagrasses, and aboveground biomass estimation and restoration for mangroves. Future research should expand estimates of lateral carbon exchange and carbonate burial and strengthen the exploration of the impacts of climate change and restoration on blue carbon. Overall, this study provides the research status of carbon cycling in vegetated blue carbon ecosystems, which favors knowledge exchanges for future research.

Plastic pollution induced by the COVID-19: Environmental challenges and outlook

The COVID-19 pandemic has also caused an environmental challenge, especially plastic pollution. This study is aimed to provide a systematic review of the current status and outlook of research on plastic pollution caused by the COVID-19 pandemic using a bibliometrics approach. The results indicate developed countries were the first to pay attention to the impact of plastics on the ocean and ecological environment during COVID-19 and conducted related research, and then developing countries followed up and started research. Research in developed countries is absolutely dominant in plastic pollution induced by the COVID-19, although the plastic pollution faced by developing countries is also very serious. The author's co-occurrence analysis shows the Matthew effect. Keyword clustering shows that plastics have a harsh chain-like impact on the ecological environment from land to ocean to atmosphere. The non-degradable components of plastic bring a serious impact the ocean ecosystems, and then pose a serious threat to the entire ecosystem environment.

Visual Analysis of International Environmental Security Management Research (1997-2021) Based on VOSviewer and CiteSpace

To investigate the international development status and hot trends in the field of environmental security management in recent years, the published the environmental security management literature from 1997 to 2021, which was retrieved from Web of Science, with VOSviewer as the main and CiteSpace as the auxiliary, through the cooperation network of authors, scientific research institutions, and countries. The keywords were visualized by clustering, time zone analysis, and burst analysis. A total of 7596 articles were retrieved, forming six main clustering labels, including 28,144 authors. The research hotspots are from the fields of personal health, society, agriculture, ecological environment, energy, and sustainable development, as well as the development of internet environmental safety management, such as big data, Bayesian networks, and conceptual frameworks. Through cluster analysis, the cooperation of major research teams and scientific research institutions and the cooperation and development between countries were analyzed. The cooperation between scientific research institutions in various countries is relatively close. The United States currently occupies a dominant and authoritative position in this field. China has cooperated more closely with the United States, Britain, Australia, and India.

Monitoring and control methods of harmful algal blooms in Chinese freshwater system: a review

Harmful algal blooms (HABs) are a worldwide problem with substantial adverse effects on the aquatic environment as well as human health, which have prompted researchers to study measures to stem and control them. Meanwhile, it is key to research and develop monitoring methods to establish early warning HABs. However, both the current monitoring methods and control methods have some shortcomings, making the field application limited. Thus, we need to improve current approaches for monitoring and controlling HABs efficiently. Based on the freshwater system features in China, we review various monitoring and control methods of HABs, summarize and discuss the problems with these methods, and propose the future development direction of monitoring and control HABs. Finally, we envision that it can combine physical, chemical, and biological methods to inhibit HAB expansion in the future, complementing each other with advantages. Further, we promise to establish a long-term strategy of controlling HABs with various algicidal bacteria co-cultivate for field applications in China. Efforts in studying algicidal bacteria must be increased to better control HABs and mitigate the risks of aquatic ecosystems and human health in China.

A Bibliometric Analysis of Solar Energy Forecasting Studies in Africa

Solar energy forecasting is considered an essential scientific aspect in supporting efforts to integrate solar energy into power grids. Moreover, solar energy forecasting plays an essential role in mitigating greenhouse gas emissions and conserving energy for future use. This study conducted a bibliometric analysis to assess solar energy forecasting research studies evolution at the continental (Africa) and southern Africa levels. Key aspects of analysis included (i) scientific research trends, (ii) nature of collaboration networks, (iii) co-occurrence of keywords and (iv) emerging themes in solar energy forecasting over the last two decades, between the years 2000–2021. The results indicate that solar energy forecasting research has, on average, expanded by 6.4% and 3.3% in Africa and southern Africa, respectively. Based on the study context, solar energy forecasting research only gained momentum in 2015, peaking in 2019, but it is generally still subtle. The scientific mapping illustrated that only South Africa ranks among the leading countries that have produced high numbers of published documents and also leads in contributions to the research area in both Africa and southern Africa. Three emerging topics were identified from the thematic map analysis—namely, “solar irradiance”, “artificial intelligence” and “clear sky”, which implies that researchers are paying attention to solar irradiance, using modelling techniques that incorporate machine learning techniques. Overall, this study contributes to scientific information on the potential bankability of renewable energy projects that could assist power utilities, governments and policymakers in Africa to enforce the green economy through accelerated decarbonisation of the energy systems and building relationships with developed countries for support and better transitioning to solar energy. From a Water–Energy–Food nexus perspective, the results of this work could assist the scientific community in Africa to take advantage of the inherent interconnectedness of water, energy and food resources, whilst also advancing the use of integrated solutions to shape the focus of solar energy research into a more systems thinking and transdisciplinary approach involving the interconnected primary resources and stakeholders pursuit of the Sustainable Development Goals.

A Bibliometric and Visualized Analysis of Research Progress and Trends in Rice Remote Sensing over the Past 42 Years (1980–2021)

Rice is one of the most important food crops around the world. Remote sensing technology, as an effective and rapidly developing method, has been widely applied to precise rice management. To observe the current research status in the field of rice remote sensing (RRS), a bibliometric analysis was carried out based on 2680 papers of RRS published during 1980–2021, which were collected from the core collection of the Web of Science database. Quantitative analysis of the number of publications, top countries and institutions, popular keywords, etc. was conducted through the knowledge mapping software CiteSpace, and comprehensive discussions were carried out from the aspects of specific research objects, methods, spectral variables, and sensor platforms. The results revealed that an increasing number of countries and institutions have conducted research on RRS and a great number of articles have been published annually, among which, China, the United States of America, and Japan were the top three and the Chinese Academy of Sciences, Zhejiang University, and Nanjing Agricultural University were the first three research institutions with the largest publications. Abundant interest was paid to “reflectance”, followed by “vegetation index” and “yield” and the specific objects mainly focused on growth, yield, area, stress, and quality. From the perspective of spectral variables, reflectance, vegetation index, and back-scattering coefficient appeared the most frequently in the frontiers. In addition to satellite remote sensing data and empirical models, unmanned air vehicle (UAV) platforms and artificial intelligence models have gradually become hot topics. This study enriches the readers’ understanding and highlights the potential future research directions in RRS.

The Hotspots and Trends in the Literature on Cleaner Production: A Visualized Analysis Based on Citespace

Cleaner production (CP) has emerged as a new concept to cope with the astronomical environmental degradation associated with the expanding scope of industrialization. We conducted a review of the scientific data on the conceptualization of “cleaner production” using published documents from the 2011–2021 period. Data were extracted from the CNKI and WOS databases—two major databases based in China and the United States, respectively. Citespace software was used to track the developmental process and trend of future research on cleaner production. We report the following findings: (1) While the literature on cleaner production in CNKI is decreasing, the literature in WOS has been increasing annually. (2) Even though clear instances of different research priorities exist between WOS and CNKI, the research problems addressed in the two databases, however, are mostly common. In terms of research collaboration, WOS is more likely to accept papers with cross-institutional authorship. The study further identified that there is no aggregation effect between Chinese research institutions. (3) In WOS, the Journal of Cleaner Production is the most popular journal for researchers, and in CNKI the Chinese Journal of Agricultural Resources and Regional Planning leads in CP publications. (4) Regarding the research hotspots, there are obvious differences between WOS and CNKI. Finally, we put forward the future prospects for cleaner production research.

Application of Artificial Neural Networks in Construction Management: A Scientometric Review

As a powerful artificial intelligence tool, the Artificial Neural Network (ANN) has been increasingly applied in the field of construction management (CM) during the last few decades. However, few papers have attempted to draw up a systematic commentary to appraise the state-of-the-art research on ANNs in CM except the one published in 2000. In the present study, a scientometric analysis was conducted to comprehensively analyze 112 related articles retrieved from seven selected authoritative journals published between 2000 and 2020. The analysis identified co-authorship networks, collaboration networks of countries/regions, co-occurrence networks of keywords, and timeline visualization of keywords, together with the strongest citation burst, the active research authors, countries/regions, and main research interests, as well as their evolution trends and collaborative relationships in the past 20 years. This paper finds that there is still a lack of systematic research and sufficient attention to the application of ANNs in CM. Furthermore, ANN applications still face many challenges such as data collection, cleaning and storage, the collaboration of different stakeholders, researchers and countries/regions, as well as the systematic design for the needed platforms. The findings are valuable to both the researchers and industry practitioners who are committed to ANNs in CM.

Modeling Chlorophyll a with Use of the SWAT Tool for the Nielba River (West-Central Poland) as an Example of an Unmonitored Watercourse

The majority of eutrophication studies focuses on lacustrine processes, thus riverine systems remain less recognized in this context. Moreover, since the availability of data related to parameters affecting this phenomenon is quite limited, modeling efforts should be considered. The current study verifies the SWAT model’s capability to simulate chlorophyll a loads for unmonitored watercourse. The analyses of the relationships between individual parameters, directly involved in the eutrophication process, help in the exploration of its dominant trends in SWAT modeling. The results obtained for the Nielba River pilot catchment (west-central Poland) showed a strong correlation of chlorophyll a with flow and surface runoff, but no relationship with temperature or solar radiation. Moreover, an impact of local conditions (hydrological features) on chlorophyll a load simulation could be traced in detail. The research specified the limitations and impact of generalization in the SWAT model on the results. Furthermore, intricacies related to the dataset statistical treatment (e.g., outliers) have been presented.

Research Status and Trends of Underwater Photosynthesis

Underwater photosynthesis is the most important metabolic activity for submerged plants since it could utilize carbon fixation to replenish lost carbohydrates and improve internal aeration by producing O2. The present study used bibliometric methods to quantify the annual number of publications related to underwater photosynthesis. CiteSpace, as a visual analytic software for the literature, was employed to analyze the distribution of the subject categories, author collaborations, institution collaborations, international (regional) collaborations, and cocitation and keyword burst. The results show the basic characteristics of the literature, the main intellectual base, and the main research powers of underwater photosynthesis. Meanwhile, this paper revealed the research hotspots and trends of this field. This study provides an objective and comprehensive analysis of underwater photosynthesis from a bibliometric perspective. It is expected to provide reference information for scholars in related fields to refine the research direction, solve specific scientific problems, and assist scholars in seeking/establishing relevant collaborations in their areas of interest.

Research trend and dynamical development of focusing on the global critical metals: a bibliometric analysis during 1991-2020

Critical metals are indispensable to a world seeking to transition away from carbon. Yet their extraction, processing, and application leave an unsustainable global environment and climate change footprint. To capture the development dynamics and research emphases of critical metals throughout their life cycle, this paper adopts bibliometrics to analyze the various stages of global critical metal flow in multiple dimensions to reveal the hot issues and future strategic trends. The research results indicate that the number of research papers on critical metals is annually rising, with remarkably rapid growth after 2010. Judging from the number of articles published by the authors and the citations, among the authors, Kawakita, Poettgen, Anwander, Inoue, and Dongmei Cui have a significant influence on critical metal research fields. The institutions with the most research on critical metals are universities, not research institutes. In addition, the focus has extended from a single discipline to the interdisciplinary development of multiple disciplines. Analysis of keywords shows that "rare metals" and "precious metals" are the most popular metals among the researched metals. The researched buzzwords of critical metals are disappearing, convergent, and merging over time. The research has focused on the mining and the whole life cycle process of extraction, treatment, and application. Based on the above characteristics, this paper tries to understand the dynamic development and evolution of global critical metals from multiple dimensions, resorting to giving a reference for follow-up-related research scholars.

Agricultural Eco-Efficiency: Challenges and Progress

The research on agricultural eco-efficiency has become an important point to deeply understand the interaction between ecological and environmental conditions and socio-economic factors as well as realize the coordinated development of agricultural economic development and environmental protection. (1) Background: This paper attempts to provide scientific support for the healthy and stable development of the agricultural economy and the sustainable development of ecological agriculture. (2) Methods: From a comprehensive perspective, this paper systematically analyze the overall situation, development trend, key fields, and hot fields of agricultural eco-efficiency in the past two decades. It consists of two complementary parts, including systematic quantitative literature review (based on CiteSpace) and traditional literature review. (3) Results: Agricultural eco-efficiency has evolved significantly with the popularization of agricultural machinery and the wide application of science and technology in the field of agricultural ecology. Its future development relies on the advances in our knowledge on theories and hypothesis, evaluation methods, impact on “socio-economic ecological” system, and drivers and regulation of agricultural eco-efficiency. For each of these fields, we find that challenges still exist. At present, the quantitative methods and index selection are not unified. We should deeply analyze the internal and external driving force of the development and change of ecological efficiency by constructing a complete theoretical framework for the research of agricultural ecological efficiency. At the same time, new technologies and methods are needed to evaluate agricultural eco-efficiency, and a balanced consensus between the improvement of agricultural eco-efficiency and the improvement of the ecological environment should be formed through empirical research.

Mapping the knowledge domain of the evolution of emergy theory: a bibliometric approach

Bibliometric and visualization tools are effective for uncovering information contained in vast amounts of literature data. We retrieved publications from the Web of Science (2008-2020) and used the Statistical Analysis Toolkit for Informetrics (SATI) and CiteSpace to conduct a bibliometric analysis of emergy studies, review the focus of the studies, summarize current research, and identify academic trends. The SATI-based charts provided an overall description of yearly published articles, literature sources, high-frequency keywords, authors, institutions, and highly cited papers. CiteSpace was applied to determine the frontiers and hotspots of emergy theory. A dual-map analysis was used to reveal the connection between multiple disciplines. Keyword clustering analysis was performed to evaluate research hotspots. Moreover, burst analysis and timeline maps presented a holistic picture of cutting-edge issues and the evolutionary trajectory of emergy studies in recent years. An alluvial flow map analysis of the landmark literature depicted the transmission of knowledge in the emergy field. In addition, this article also evaluated the current status of collaborative research in emergy-related fields. The results can provide a reference for researchers to explore hot issues or target a specific field of study.

Can COVID-19 and environmental research in developing countries support these countries to meet the environmental challenges induced by the pandemic?

Meeting the huge impact of COVID-19 on the environment requires better research on pandemic and pollution. What is the research capacity of the COVID-19 and environment in developing countries? Can this research capacity support developing countries to deal with the environmental challenges induced by the pandemic? This work is addressed to comprehensively assess the research capacity of the COVID-19 and environment in developing countries using bibliometric analysis techniques and content analysis approach to mining the Web of Science database. The results of data mining were unexpected: the global leader of the COVID-19 and environmental research was not these developed countries, but these developing countries so far, the end of 2020. Developing countries have published more papers on the pandemic and environment than developed countries, and developing countries also dominate pandemic and environmental research in terms of research institutions and authors. The results showed that (i) the impact of COVID-19 and the environment was bidirectional; (ii) energy consumption has posed great impact on environment; (iii) application of big data and artificial intelligence played an important role in improving environmental quality during the COVID-19 pandemic. Finally, policy recommendations such as formulating relevant policies and environmental standards, strengthening international exchanges and cooperation, and adjusting and improving energy consumption structure that were put forward for developing countries to meet the environmental challenges induced by the pandemic were offered. Graphical abstract.

Changing Dietary Behavior for Better Biodiversity Preservation: A Preliminary Study

Broadly consumed dietary patterns, such as the European and Western ones, are exerting pressures on biodiversity both in Europe and globally, and shifting toward a sustainable dietary pattern has thus become a must. This paper constitutes a preliminary communication of the results of a research project on the issue. In this study, the pressures of three dietary patterns (European, Western, and Mediterranean) on biodiversity are addressed in terms of land use, water use, greenhouse gas emissions, and eutrophication impact indicators. The environmental impacts are calculated based on a compositional analysis of each dietary pattern and the environmental footprints of the corresponding food groups. Food balance sheets published by the FAO are used as a basis for the compositional analysis, while the environmental footprints of each of the representative food products are retrieved from related life cycle assessment (LCA) studies. The results show that a shift from the European to the Mediterranean dietary pattern would lead to 10 m²/capita/day land savings, 240 L/capita/day water savings, 3 kg CO₂/capita/day reduction in greenhouse gas emissions, and 20 gPO₄eq/capita/day reductions in eutrophication potential. Likewise, a shift from the Western to the Mediterranean dietary pattern would lead to 18 m²/capita/day land savings, 100 L/capita/day water savings, 4 kg CO₂/capita/day reduction in greenhouse gas emissions, and 16 gPO₄eq/capita/day reduction in eutrophication potential. Based on these findings, it is clear that this shift is urgently needed as a step toward environmentally sustainable dietary patterns, such as the Mediterranean one, to preserve biodiversity for future generations.

Knowledge domain and emerging trends in nanoparticles and plants interaction research: A scientometric analysis

The potential releases of nanoparticles (NPs) into soil medium have drawn considerable attention due to the increasing production and application of NPs worldwide. Understanding the interactions between NPs and plants is particularly important to assess the risks of NPs in the soil ecosystem. Although important knowledge has been gained about the NPs-plants interactions, current results of numerous published articles are still scattered. Therefore, this paper reviews the scientific progress in the NPs-plants interactions via a scientometric analysis to identify the main gaps and to provide future perspectives. Scientific documents on the interaction of nanoparticles and plant research during the period January 2000-July 2020 have been collected from Web of Science core collection and analyzed using CiteSpace. Overall, 9 scientometric indicators, i.e. literature quantity and growth trend, contributing countries, authors, institutions, keywords, cited journals, cited authors, and cited articles, are employed to understand the results retrieved from the 961 documents collected. The number of studies on nano-plant interaction research has been growing at an average annual rate of 56%. 71 countries and around 3380 authors have contributed to this field. Among the cited journals, Environmental Science and Technology stands out as the most-cited journal followed by Science of the Total Environment and Environmental Pollution, respectively. Moreover, the keyword citation burst, an indicator of the most active area of research or emerging trend, indicates that the beneficial side of nanoparticles and the trophic transfer require further exploration. This paper will be beneficial for fully understanding the salient research themes and the research trends of nano-plant interaction in future.

A webGIS Application to Assess Seawater Quality: A Case Study in a Coastal Area in the Northern Aegean Sea

The assessment of seawater quality in coastal areas is an important issue as it is related to the welfare of coastal ecosystems, a prerequisite for the provision of the related ecosystem services. During the last decades, marine eutrophication has become an important problem in coastal waters as a result of nutrient inputs increase. Consequently, there is need for appropriate methods and tools to assess the eutrophication status of seawater which should be user-friendly to coastal managers and support the adoption of effective plans for the protection and sustainable development of the coastal environment. In this framework, a user-friendly webGIS application has been developed and the Strait of Mytilene at the southeastern part of the Island of Lesvos in the NE Aegean Sea, Greece, was used as a case study. The methodology includes, as a first step, the evaluation of the accuracy of spatial interpolators widely applied in oceanographic studies for assessing the spatial distribution of relevant variables. The most appropriate interpolator revealed for each variable is subsequently applied for the production of the representative thematic layer. The second step involves the integration of the information from the optimal thematic layers representing the spatial distributions of the variables under study; as a result, a new thematic layer illustrating the eutrophication status of the study area is produced. The webGIS application is fully available via a web browser and provides a number of geoprocessing modules developed in Python which implement the user interface, the application of the interpolation analytical tasks, the statistical evaluation toolset and the integration of the optimal interpolated layers. Suggestions for further improvement of the proposed webGIS application are discussed.

Past, Present, and Future of Virtual Water and Water Footprint

Virtual water and water footprint have received increasing attention. However, no published research has conducted a quantitative and objective review of this field from the perspective of bibliometrics. Therefore, based on the Web of Science Core Collection, this study employs CiteSpace to quantitatively analyze and visualize information about countries, institutions, and authors that have conducted virtual water and water footprint research over the past two decades. As of July 2020, there were 1592 publications on virtual water and water footprint, showing an increasing trend overall. The annual average number of publications was only 7.4 in 1998–2008, while it was 126.5 in 2009–2019. Among them, up to 618 publications in the field of environmental science, accounting for 46%. China was the most productive country with a total of 344 articles, but the Netherlands had the strongest influence with a betweenness centrality of 0.33, indicating its leading position. It is essential to strengthen cooperation between developed (water-rich) and developing (water-poor) countries and to incorporate virtual water into social water cycle research. This study is expected to provide a new perspective for investigating the research frontiers and hot spots of virtual water and water footprint research.

Ecological and human health risk assessment

The literature review presented in this paper includes the ecological and human health risk assessment in the form of receptors in the environment. The main objective of this review to highlight a summary of the many studies undertaken in the year 2019. The first part of the review covers the papers published on the health risk assessment related to human and ecological health. This article focuses on methods and tools utilized for the analysis of scientific studies and the data. The review provides main issues such as interpretation of data, uncertainty, and policies related to the management of risks. The ecological and human health risk assessment is divided into two main sections. Each of these sections presents in broad the risk assessment process namely pollution studies, remediation, and tools required for the management of natural resources and the environment.

Flood Risk Analysis and Assessment, Applications and Uncertainties: A Bibliometric Review

Studies looking at flood risk analysis and assessment (FRA) reviews are not customary, and they usually approach to methodological and spatial scale issues, uncertainty, mapping or economic damage topics. However, most of these reviews provide a snapshot of the scientific state of the art of FRA that shows only a partial view, focused on a limited number of selected methods and approaches. In this paper, we apply a bibliometric analysis using the Web of Science (WoS) database to assess the historic evolution and future prospects (emerging fields of application) of FRA. The scientific production of FRA has increased considerably in the past decade. At the beginning, US researchers dominated the field, but now they have been overtaken by the Chinese. The Netherlands and Germany may be highlighted for their more complete analyses and assessments (e.g., including an uncertainty analysis of FRA results), and this can be related to the presence of competitive research groups focused on FRA. Regarding FRA fields of application, resilience analysis shows some growth in recent years while land planning, risk perception and risk warning show a slight decrease in the number of papers published. Global warming appears to dominate part of future FRA production, which affects both fluvial and coastal floods. This, together with the improvement of economic evaluation and psycho-social analysis, appear to be the main trends for the future evolution of FRA. Finally, we cannot ignore the increase in analysis using big data analysis, machine learning techniques, and remote sensing data (particularly in the case of UAV sensors data).

Reply to the rebuttal to: Li et al. "Dynamic analysis of international green behavior from the perspective of the mapping knowledge domain," Environmental Science and Pollution Research, vol. 26, pp. 6087-6098

Recently, Dr. Yuh-shan Ho discussed the search methods of the paper "Dynamic analysis of international green behavior from the perspective of the mapping knowledge domain" Li et al. (Environ Sci Pollut Res 26:6087-6098, 2019a). In fact, Ho and co-workers have used the search methods in several papers Ivanović et al. (Scientometrics, 105:145-160, 2015); Monge-Nájera & Ho (Rev Biol Trop 63:1255-1266, 2015); Ho & Hartley (Br J Psychol, 107:768-780, 2016). In order to reply to the comments, this letter supplementarily explains the characteristics, scope, and limitations of search methods. In addition, the letter states that researchers can use improved methods suggested by Dr. Ho in future studies.