Next Article in Journal
Hybrid Bermudagrass and Tall Fescue Turfgrass Irrigation in Central California: II. Assessment of NDVI, CWSI, and Canopy Temperature Dynamics
Next Article in Special Issue
Potential of the Biomass of Plants Grown in Trace Element-Contaminated Soils under Mediterranean Climatic Conditions for Bioenergy Production
Previous Article in Journal
The Distribution of Soil Micro-Nutrients and the Effects on Herbage Micro-Nutrient Uptake and Yield in Three Different Pasture Systems
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Agronomy
Volume 11
Issue 9
10.3390/agronomy11091729
agronomy-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Hyperaccumulators for Potentially Toxic Elements: A Scientometric Analysis

by
Dongming Zhang
1,2,
Miles Dyck
3,
Lana Filipović
4,
Vilim Filipović
4,
Jialong Lv
1,2 and
Hailong He
1,*
1
College of Natural Resources and Environment, Northwest A&F University, Yangling, Xianyang 712100, China
2
Key Laboratory of Plant Nutrition and the Agri-Environment in Northwest China (Ministry of Agriculture), Northwest A&F University, Yangling, Xianyang 712100, China
3
Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2H1, Canada
4
Department of Soil Amelioration, Division for Agroecology, University of Zagreb Faculty of Agriculture, 10000 Zagreb, Croatia
*
Author to whom correspondence should be addressed.
Agronomy 2021, 11(9), 1729; https://doi.org/10.3390/agronomy11091729
Submission received: 13 July 2021 / Revised: 25 August 2021 / Accepted: 26 August 2021 / Published: 29 August 2021
(This article belongs to the Special Issue New Phytoremediation in Trace Elements Contaminated Soils)
Browse Figures
Versions Notes

Abstract

:
Phytoremediation is an effective and low-cost method for the remediation of soil contaminated by potentially toxic elements (metals and metalloids) with hyperaccumulating plants. This study analyzed hyperaccumulator publications using data from the Web of Science Core Collection (WoSCC) (1992–2020). We explored the research status on this topic by creating a series of scientific maps using VOSviewer, HistCite Pro, and CiteSpace. The results showed that the total number of publications in this field shows an upward trend. Dr. Xiaoe Yang is the most productive researcher on hyperaccumulators and has the broadest international collaboration network. The Chinese Academy of Sciences (China), Zhejiang University (China), and the University of Florida (USA) are the top three most productive institutions in the field. China, the USA, and India are the top three most productive countries. The most widely used journals were the International Journal of Phytoremediation, Environmental Science and Pollution Research, and Chemosphere. Co-occurrence and citation analysis were used to identify the most influential publications in this field. In addition, possible knowledge gaps and perspectives for future studies are also presented.

1. Introduction

Potentially toxic elements (PTEs), including metals and metalloids, are important pollutants originating from the mineralization of parent materials (geogenic origin) or human activities (anthropogenic origin), and their concentration in the environment increases year by year [1]. Increased concentrations of PTEs in the environment pose a severe threat to human, animal, and plant health. For example, the frequently reported “blood lead incident” [2], “cadmium rice” [3], and “heavy metal contaminated vegetables” [4] are all associated with PTE pollution. In addition, PTEs may pollute the air through wind erosion [5,6] as well as surface and underground water bodies through surface runoff or deep percolation [7]. Phytoremediation is an efficient and environmentally friendly remediation strategy for PTEs pollution [8,9], which can be used for the reclamation of contaminated soils without disturbing soil fertility and biodiversity [10,11]. Hyperaccumulators can generally accumulate large amounts of PTEs at concentrations 10 to 100 times higher than non-hyperaccumulating plants can tolerate [12]. In addition, Macnair [13] stated that the shoot-to-root quotient of concentrations for PTEs in super-enriched plants is usually >1. Besides using plants in situ, other ex-situ strategies, such as excavation of polluted soil followed by a certain treatment, are also possible, although they are much more labor- and cost-demanding. Therefore, hyperaccumulators are considered a green alternative to solve the issue of PTEs pollution and are a more practical approach for large-scale applications.
Hyperaccumulating plants of PTEs have developed certain adaptation mechanisms that enable them to tolerate high concentrations in their tissues [14,15,16,17,18,19,20]. These tolerance mechanisms may include (1) organometallic complexes with donor ligands, including organic acids [21,22], cysteine [23,24], nicotinamide [25,26], histidine [27,28,29,30], and other thiols with low molecular weight [31]; (2) transportation capability [32], e.g., it is thought that arsenic (As) uptake by Pteris vittata is achieved through a high-affinity phosphate transport system [33]; (3) compartmentation potential [34,35], e.g., Asemaneh et al. [34] proposed that cellular and subcellular compartmentation are both possible mechanisms for nickel (Ni) tolerance employed by the serpentine Alyssum murale and Alyssum bracteatum; and (4) the ability to store these complexes in the vacuoles of leaf storage cells [36]. Tolerance is a key prerequisite for the accumulation and phytoremediation of PTEs [37,38]. Plants are not considered to be hyperaccumulators or super-enriched if they cannot tolerate high concentrations of PTEs in their tissues and complete their life cycle. However, for a successful hyperaccumulating plant, the ability to produce high biomass is also important, in addition to their ability to uptake high concentrations of PTEs without having a negative impact on their physiological processes. For instance, Chen and Cutright [39] found that ethylene diamine tetraacetic acid (EDTA) could increase the concentration of cadmium (Cd) in the stem of sunflower, but the total biomass of plants decreased sharply. Ent et al. [40] described that a hyperaccumulator should include extreme tolerance and have a very high bioconcentration factor.
As the emission of PTEs into the environment by continuously expanding urbanization and agriculturalization is increasing worldwide, it is expected that the topic of PTEs-hyperaccumulating plants and their potential for removing these PTEs from the contaminated soils will keep increasing in the future. Scientometric analysis of hyperaccumulators for remediating contaminated soils is thus a useful tool for identifying and summarizing the main research points relevant to expanding, publishing, and applying up-to-date knowledge on this topic. Previous studies have reviewed the applications and future trends in phytoremediation [8,36,41]. There are also bibliometric studies that map the overall research status of PTEs in the environment [42,43,44,45]. However, there is no such study focusing on the research status of the topic of hyperaccumulators that have the potential for PTE removal from contaminated soils. The objective of this study was therefore to reveal the development history of research focused on hyperaccumulators from the bibliometric perspective and provide useful information for scientists working in this research area.

2. Materials and Methods

The Science Citation Index Expanded (SCI-EXPANDED) database of the Web of Science Core Collection (WoSCC) contains literature data since 1992. The data between January 1992 and December 2020 were downloaded from the WoSCC on 10 February 2021 for analysis. The query sets used for the literature search were: “TS = (hyperaccumulating plants OR hyperaccumulat* OR “accumulator plants” OR phytoremediation OR hyperaccumulation OR Phytoextraction) AND TS = (heavy metal OR lead (Pb) OR cadmium OR copper OR Zinc OR mercury OR arsenic OR chromium OR nickel OR antimony OR aluminum OR contaminated OR polluted)”. Document types of articles, letters, notes, books/book chapters, data papers, database reviews, proceedings papers, and reviews written in English were retained. The search was then saved as a text file containing “full record and citation data” for bibliometric analysis.
VOSviewer v1.6.15 [46], HistCite Pro (history of cite) [47], and CiteSpace v5.7.R5 [48] were used to analyze the retrieved literature. VOSviewer uses co-citation [49] and bibliographic coupling to generate a visual atlas for the analysis of journals, authors, countries, institutions, and keywords [46]. Research hotspots in specific fields are generally explored through keyword analysis. HistCite Pro is a more concise and convenient version of the out-of-service HistCite modified by Wang Qing from the Chinese Academy of Sciences. Citation analysis in Histcite Pro can identify highly cited papers and references. CiteSpace is a citation network analysis tool developed by Professor Chen Chaomei, and it was used to develop the strongest citation bursts map of keywords.

3. Results and Discussion

3.1. Annual Publication Trend

A total of 13,239 publications were retrieved from the WoSCC database. Figure 1a shows an increasing trend in the number of publications in phytoremediation during the period from 1992 to 2020. It is expected that there will be more publications in the future. In addition, the majority of the papers were articles (93.22%), followed by reviews (6.68%), book chapters (0.22%), letters (0.09%), and notes (0.01%). The top ten Web of Science categories are shown in Figure 1b. Among them, environmental sciences was the subject area with the greatest volume of publications on hyperaccumulators, accounting for 58.15% of the total papers, followed by plant sciences (17.57%), engineering environmental (8.94%), soil science (7.39%), toxicology (5.57%), biotechnology applied microbiology (5.56%), agronomy (5.25%), water resources (5.08%), ecology (4.24%), and biochemistry and molecular biology (3.78%).

3.2. Citation Network of Authors, Organizations, and Countries

A total of 457 authors met the threshold of a minimum of 10 publications per author. They consisted of 31 clusters in different colors (Figure 2), which indicates that there are 31 closely related groups working on hyperaccumulators for PTE pollution. Among them, Dr. Xiaoe Yang from Zhejiang University (Zhejiang, China) had more international collaborations than the other authors, as indicated by the greatest value of total links (TLS) of 294, followed by Dr. Xun Wang from Sichuan Agricultural University (Sichuan, China) (TLS = 247) and Dr. Yongming Luo from the Chinese Academy of Sciences (Beijing, China) (TLS = 211).
Some of the most productive authors with over 100 publications on this topic include Dr. Xiaoe Yang (N = 131), Dr. Alan J.M. Baker (N = 108) from the University of Melbourne (Melbourne, Australia), Dr. Ma Lena Q (N = 103) from Zhejiang University (Zhejiang, China), Dr. Yongming Luo (N = 101) and Dr. Jaco Vangronsveld (N = 101) from University of Hasselt (Diepenbeek, Belgium). It is interesting to note that Dr. Xiaoe Yang has conducted much research on Sedum alfredii Hance (a Zn-hyperaccumulator plant species) [50,51,52,53,54], including the phytoremediation of combined contamination with zinc (Zn), copper (Cu), and other PTEs [55,56,57,58]. Dr. Alan J.M. Baker investigated the effects of a variety of hyperaccumulators [59,60,61] on pollution of PTEs, including nickel (Ni) [62], manganese (Mn) [63], and cadmium (Cd) [64], among other metals and metalloids. These studies from Dr. Alan J.M. Baker were highly cited by studies related to hyperaccumulator research retrieved from the Web of Science, as indicated by the greatest total local citation score (TLCS) of 6262. They were also highly cited by other related research as indicated by the greatest total global citation score (TGCS) of 10,248.
The top 10 organizations and countries are shown in Table 1 and Figure 3. Six of the top 10 institutions were from China, which makes China the most productive country on hyperaccumulator research, with N = 3554 (Table 1). China was followed by the USA (N = 1772) and India (N = 1052). Fewer studies were found from Africa, the Middle East, and South America (Figure 3), but the underlying reason remains unknown. It was noted that the per-article citations (TGCS/N = 51) of the USA were much higher than the other countries. This is also true for the University of Florida (Gainesville, FL, USA), whose TGCS/N (54) was higher than the other top 10 productive organizations.

3.3. Most Recognized Journals

The 13,239 studies on hyperaccumulators were published in 1126 journals, with the top 10 most utilized journals listed in Figure 4. It is understood that most of these journals are related to phytoremediation and environmental pollution. The International Journal of Phytoremediation was ranked No. 1, publishing over 1000 papers on this topic, followed by Environmental Science and Pollution Research (N = 813) and Chemosphere (N = 705).

3.4. Highly Impacted Studies

Citation analysis with HistCite Pro showed that papers numbered 135 [60], 138 [65], 144 [66], 145 [67], and 149 [68] were highly cited, as indicated by the larger circles and more surrounding arrows (Figure 5). These studies have greatly contributed to the promotion of the application of phytoremediation. The papers numbered 135 [60], 411 [69], 516 [70], and 2998 [71] explained molecular mechanisms of plant tolerance and homeostasis. The papers 138 [65], 3063 [72], 4246 [16], and 5661 [8] highlighted the applications of phytoremediation and more possibilities for the future. The paper numbered 508 [73] reported an As-hyperaccumulator plant species, Pteris vittate. The paper numbered 1128 [74] reported for the first time a new Cd-hyperaccumulator plant (Sedum alfredii Hance). Paper 457 [75] demonstrated that the mesophyll cells in the leaves of plants are the major storage sites for Zn and Cd. Paper 522 [76] introduced the phytoextraction of PTEs and considered it an economical and effective method [77,78,79].

3.5. Co-Occurrence Analysis of Keywords

Keywords are generally the core of a study and can reveal the research topic in a particular field. The VOSviewer software was used to draw the keyword co-occurrence density map of the 13,239 publications (Figure 6). Phytoremediation was undoubtedly the most frequently used keyword, with over 1000 occurrences. It is not surprising that the terms “phytoremediation”, “phytoextraction”, and “accumulation” stand out in Figure 6, as they are commonly used keywords. Phytoremediation is used to describe the ability of hyperaccumulators to remove PTEs from soil; therefore, terms such as “tolerance”, “removal”, “antioxidant enzymes”, and “rhizosphere” are mentioned repeatedly [75,95,96]. The use of terms for PTE, such as “zinc” [97,98], “cadmium” [74,99], and “copper” [100,101,102,103], as well as hyperaccumulators, such as “thlaspi-caerulescens” [14,104,105], indicates that the phytoremediation of particular metal (i.e., zinc (Zn), cadmium (Cd), and copper (Cu))-contaminated soils has been extensively studied. It should be noted that the keyword co-occurrence density map can only show the hotspots of phytoremediation research in a qualitative way, and it cannot reflect the temporal change, which will be further resolved in the next section.

3.6. Keywords with the Strongest Citation Bursts

Figure 7 shows the temporal change of frequently appearing keywords or research hotspots with the strongest citation bursts analysis using CiteSpace. The red lines represent the time periods for a keyword with a strong burst. “Nickel”, “zinc”, and “cadmium” were the most-studied PTEs from the 1990s to 2000s. “Metal tolerance” in “plant”, such as “brassicaceae” received widespread attention from 1994 to 2007. The hot topic from 1996 to 1999 was the “uptake” and “transport” of PTEs by “brassicaceae” plants, such as “thlaspi caerulescen” and “Indian mustard”. New hyperaccumulators continued to be discovered, as indicated by “fern” and “arabidopsis halleri” in the 2000s. The concern of PTEs on “health risk” and the applications of “biochar” to remediate soil heavy metal pollution was a hot topic in 2018–2020.

4. Conclusions and Perspectives

In this study, bibliometrics were used to analyze the research status of the topic of hyperaccumulators for remediating PTE-contaminated soil from 1992 to 2020. The results show that the number of publications in this field increased steadily and rapidly over the past three decades. The most productive authors, organizations, and countries were identified with co-authorship network analysis. Dr. Yang Xiaoe from Zhejiang University (Zhejiang, China), Dr. Alan J.M. Baker from the University of Melbourne (Melbourne, Australia), and Dr. Ma Lena Qi from Zhejiang University (Zhejiang, China) were the three most productive researchers. The Chinese Academy of Sciences (Beijing, China), Zhejiang University (Zhejiang, China), and the University of Florida (Gainesville, USA) were the top three institutions in the field. China, the USA, and India were the top three contributing countries. International Journal of Phytoremediation, Environmental Science and Pollution Research, and Chemosphere were the most influential periodicals. The co-occurrence and strong burst analysis of keywords identified the research hotspots and their evolution with time and provided useful information for invoice and experts alike to better understand the research status of hyperaccumulators.
Hyperaccumulators are of great significance for the phytoremediation of soil contaminated by PTEs, and numerous studies have been conducted over the past decades. However, it was noted that there is still a lack of comprehensive databases collating the currently available hyperaccumulators, their characteristics (e.g., description, classification, distribution, collection of records, and analysis of data), and applications, examples, or demos [106]. In addition, there is a lack of methods that can visualize the transport and accumulation of PTEs in plants; thus, the use of computed tomography is a promising technique. Although numerous studies have investigated the transport and accumulation of PTEs in plants, they are mainly based on destructive sampling methods and cannot be used to monitor the spatio-temporal change of these characteristics in live plants. Cost-effective tools that are suited for in situ and continuous measurement are required.
Because of the limitations of VOSViewer itself, such as synonyms that cannot be intelligently merged and the effect of search methods, this study does not include all the results of PTEs and hyperaccumulators. In recent years, with the continuous optimization of software and the continuous improvement of analysis methods, we will overcome these deficiencies in the future to obtain more detailed and accurate research conclusions.

Author Contributions

Conceptualization, H.H.; methodology, H.H.; software, D.Z.; resources, M.D.; data curation, D.Z.; writing—original draft preparation, D.Z. and H.H.; writing—review and editing, J.L., M.D., L.F., V.F. and H.H.; supervision, H.H.; funding acquisition, J.L. and H.H. All authors have read and agreed to the published version of the manuscript.

Funding

Funding for this research was provided in part by the Natural Science Foundation of China (NSFC, Grant No. 42077135), the Fundamental Research Funds for the Central Universities at the Northwest A&F University (No. 2452015287), and the 111 project (No. B12007).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Govindasamy, C.; Arulpriya, M.; Ruban, P.; Jenifer, L.F.; Ilayaraja, A. Concentration of heavy metals in Seagrasses tissue of the Palk Strait, Bay of Bengal. Int. J. Environ. Sci. 2011, 2, 145–153. [Google Scholar]
  2. Feinberg, A.; McKelvey, W.; Hore, P.; Kanchi, R.; Parsons, P.J.; Palmer, C.D.; Thorpe, L.E. Declines in adult blood lead levels in New York City compared with the United States, 2004–2014. Environ. Res. 2018, 163, 194–200. [Google Scholar] [CrossRef]
  3. Gu, Y.; Wang, P.; Zhang, S.; Dai, J.; Chen, H.P.; Lombi, E.; Howard, D.L.; van der Ent, A.; Zhao, F.J.; Kopittke, P.M. Chemical Speciation and Distribution of Cadmium in Rice Grain and Implications for Bioavailability to Humans. Environ. Sci. Technol. 2020, 54, 12072–12080. [Google Scholar] [CrossRef] [PubMed]
  4. Woldetsadik, D.; Drechsel, P.; Keraita, B.; Itanna, F.; Gebrekidan, H. Heavy metal accumulation and health risk assessment in wastewater-irrigated urban vegetable farming sites of Addis Ababa, Ethiopia. Int. J. Food Contam. 2017, 4, 9. [Google Scholar] [CrossRef]
  5. Feng, W.; Guo, Z.; Xiao, X.; Peng, C.; Shi, L.; Ran, H.; Xu, W. Atmospheric deposition as a source of cadmium and lead to soil-rice system and associated risk assessment. Ecotoxicol. Environ. Saf. 2019, 180, 160–167. [Google Scholar] [CrossRef]
  6. Shotyk, W.; Weiss, D.; Appleby, P.; Cheburkin, A.; Frei, R.; Gloor, M.; Kramers, J.D.; Reese, S.; Van Der Knaap, W.O. History of atmospheric lead deposition since 12,370 14C yr BP from a peat bog, Jura Mountains, Switzerland. Science 1998, 281, 1635–1640. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  7. Abdelwaheb, M.; Jebali, K.; Dhaouadi, H.; Dridi-Dhaouadi, S. Adsorption of nitrate, phosphate, nickel and lead on soils: Risk of groundwater contamination. Ecotoxicol. Environ. Saf. 2019, 179, 182–187. [Google Scholar] [CrossRef]
  8. Ali, H.; Khan, E.; Sajad, M.A. Phytoremediation of heavy metals-Concepts and applications. Chemosphere 2013, 91, 869–881. [Google Scholar] [CrossRef] [PubMed]
  9. Adamidis, G.C.; Aloupi, M.; Mastoras, P.; Papadaki, M.I.; Dimitrakopoulos, P.G. Is annual or perennial harvesting more efficient in Ni phytoextraction? Plant Soil 2017, 418, 205–218. [Google Scholar] [CrossRef]
  10. Xiao, R.; Ali, A.; Wang, P.; Li, R.; Tian, X.; Zhang, Z. Comparison of the feasibility of different washing solutions for combined soil washing and phytoremediation for the detoxification of cadmium (Cd) and zinc (Zn) in contaminated soil. Chemosphere 2019, 230, 510–518. [Google Scholar] [CrossRef] [PubMed]
  11. Zloch, M.; Kowalkowski, T.; Tyburski, J.; Hrynkiewicz, K. Modeling of phytoextraction efficiency of microbially stimulated Salix dasyclados L. in the soils with different speciation of heavy metals. Int. J. Phytoremediat. 2017, 19, 1150–1164. [Google Scholar] [CrossRef]
  12. Kukier, U.; Peters, C.A.; Chaney, R.L.; Angle, J.S.; Roseberg, R.J. The effect of pH on metal accumulation in two Alyssum species. J. Environ. Qual. 2004, 33, 2090–2102. [Google Scholar] [CrossRef] [PubMed]
  13. Macnair, M.R. The Hyperaccumulation of Metals by Plants. In Advances in Botanical Research; Callow, J.A., Ed.; Elsevier: Amsterdam, The Netherlands, 2003; Volume 40, pp. 63–105. [Google Scholar]
  14. Assuncao, A.G.L.; Schat, H.; Aarts, M.G.M. Thlaspi caerulescens, an attractive model species to study heavy metal hyperaccumulation in plants. New Phytol. 2003, 159, 351–360. [Google Scholar] [CrossRef] [PubMed]
  15. Luo, J.P.; Tao, Q.; Jupa, R.; Liu, Y.K.; Wu, K.R.; Song, Y.C.; Li, J.X.; Huang, Y.; Zou, L.Y.; Liang, Y.C.; et al. Role of Vertical Transmission of Shoot Endophytes in Root-Associated Microbiome Assembly and Heavy Metal Hyperaccumulation in Sedum alfredii. Environ. Sci. Technol. 2019, 53, 6954–6963. [Google Scholar] [CrossRef]
  16. Rascio, N.; Navari-Izzo, F. Heavy metal hyperaccumulating plants: How and why do they do it? And what makes them so interesting? Plant Sci. 2011, 180, 169–181. [Google Scholar] [CrossRef]
  17. Schat, H.; Llugany, M.; Vooijs, R.; Hartley-Whitaker, J.; Bleeker, P.M. The role of phytochelatins in constitutive and adaptive heavy metal tolerances in hyperaccumulator and non-hyperaccumulator metallophytes. J. Exp. Bot. 2002, 53, 2381–2392. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  18. Sheoran, V.; Sheoran, A.S.; Poonia, P. Role of Hyperaccumulators in Phytoextraction of Metals from Contaminated Mining Sites: A Review. Crit. Rev. Environ. Sci. Technol. 2011, 41, 168–214. [Google Scholar] [CrossRef]
  19. Yang, X.; Feng, Y.; He, Z.L.; Stoffella, P.J. Molecular mechanisms of heavy metal hyperaccumulation and phytoremediation. J. Trace Elem. Med. Biol. 2005, 18, 339–353. [Google Scholar] [CrossRef] [PubMed]
  20. Sun, R.-L.; Zhou, Q.-X. Heavy metal tolerance and hyperaccumulation of higher plants and their molecular mechanisms: A review. Zhiwu Shengtai Xuebao 2005, 29, 497–504. [Google Scholar]
  21. Afshan, S.; Ali, S.; Bharwana, S.A.; Rizwan, M.; Farid, M.; Abbas, F.; Ibrahim, M.; Mehmood, M.A.; Abbasi, G.H. Citric acid enhances the phytoextraction of chromium, plant growth, and photosynthesis by alleviating the oxidative damages in Brassica napus L. Environ. Sci. Pollut. Res. 2015, 22, 11679–11689. [Google Scholar] [CrossRef]
  22. Agrawal, B.; Czymmek, K.J.; Sparks, D.L.; Bais, H.P. Transient Influx of Nickel in Root Mitochondria Modulates Organic Acid and Reactive Oxygen Species Production in Nickel Hyperaccumulator Alyssum murale. J. Biol. Chem. 2013, 288, 7351–7362. [Google Scholar] [CrossRef] [Green Version]
  23. Adams, E.; Miyazaki, T.; Hayaishi-Satoh, A.; Han, M.; Kusano, M.; Khandelia, H.; Saito, K.; Shin, R. A novel role for methyl cysteinate, a cysteine derivative, in cesium accumulation in Arabidopsis thaliana. Sci. Rep. 2017, 7, 182–190. [Google Scholar] [CrossRef] [Green Version]
  24. Dai, J.L.; Balish, R.; Meagher, R.B.; Merkle, S.A. Development of transgenic hybrid sweetgum (Liquidambar styraciflua x L-formosana) expressing gamma-glutamylcysteine synthetase or mercuric reductase for phytoremediation of mercury pollution. New For. 2009, 38, 35–52. [Google Scholar] [CrossRef]
  25. Orcen, N. Determination of Cytoplasmic Inheritance Role in Heavy Metal Hyperaccumulation Mechanism of Tobacco Plant. Fresenius Environ. Bull. 2020, 29, 700–705. [Google Scholar]
  26. Ben Massoud, M.; Sakouhi, L.; Chaoui, A. Effect of plant growth regulators, calcium and citric acid on copper toxicity in pea seedlings. J. Plant Nutr. 2019, 42, 1230–1242. [Google Scholar] [CrossRef]
  27. Amari, T.; Lutts, S.; Taamali, M.; Lucchini, G.; Sacchi, G.A.; Abdelly, C.; Ghnaya, T. Implication of citrate, malate and histidine in the accumulation and transport of nickel in Mesembryanthemum crystallinum and Brassica juncea. Ecotoxicol. Environ. Saf. 2016, 126, 122–128. [Google Scholar] [CrossRef]
  28. Ingle, R.A.; Mugford, S.T.; Rees, J.D.; Campbell, M.M.; Smith, J.A.C. Constitutively high expression of the histidine biosynthetic pathway contributes to nickel tolerance in hyperaccumulator plants. Plant Cell 2005, 17, 2089–2106. [Google Scholar] [CrossRef] [Green Version]
  29. Zemanova, V.; Pavlik, M.; Pavlikova, D.; Tlustos, P. The significance of methionine, histidine and tryptophan in plant responses and adaptation to cadmium stress. Plant Soil Environ. 2014, 60, 426–432. [Google Scholar] [CrossRef]
  30. Wycisk, K.; Kim, E.J.; Schroeder, J.I.; Kramer, U. Enhancing the first enzymatic step in the histidine biosynthesis pathway increases the free histidine pool and nickel tolerance in Arabidopsis thaliana. FEBS Lett. 2004, 578, 128–134. [Google Scholar] [CrossRef]
  31. Callahan, D.L.; Baker, A.J.M.; Kolev, S.D.; Wedd, A.G. Metal ion ligands in hyperaccumulating plants. J. Biol. Inorg. Chem. 2006, 11, 2–12. [Google Scholar] [CrossRef]
  32. Lei, M.; Wan, X.M.; Huang, Z.C.; Chen, T.B.; Li, X.W.; Liu, Y.R. First evidence on different transportation modes of arsenic and phosphorus in arsenic hyperaccumulator Pteris vittata. Environ. Pollut. 2012, 161, 1–7. [Google Scholar] [CrossRef]
  33. Tu, C.; Ma, L.Q. Effects of arsenate and phosphate on their accumulation by an arsenic-hyperaccumulator Pteris vittata L. Plant Soil 2003, 249, 373–382. [Google Scholar] [CrossRef]
  34. Asemaneh, T.; Ghaderian, S.M.; Crawford, S.A.; Marshall, A.T.; Baker, A.J.M. Cellular and subeellular compartmentation of Ni in the Eurasian serpentine plants Alyssum bracteatum, Alyssum murale (Brassicaceae) and Cleome heratensis (Capparaceae). Planta 2006, 225, 193–202. [Google Scholar] [CrossRef] [PubMed]
  35. Yang, X.; Li, T.Q.; Yang, J.C.; He, Z.L.; Lu, L.L.; Meng, F.H. Zinc compartmentation in root, transport into xylem, and absorption into leaf cells in the hyperaccumulating species of Sedum alfredii Hance. Planta 2006, 224, 185–195. [Google Scholar] [CrossRef] [PubMed]
  36. Miransari, M. Hyperaccumulators, arbuscular mycorrhizal fungi and stress of heavy metals. Biotechnol. Adv. 2011, 29, 645–653. [Google Scholar] [CrossRef]
  37. Clemens, S. Developing tools for phytoremediation: Towards a molecular understanding of plant metal tolerance and accumulation. Int. J. Occup. Med. Environ. Health 2001, 14, 235–239. [Google Scholar] [PubMed]
  38. Alcantara-Martinez, N.; Guizar, S.; Rivera-Cabrera, F.; Anicacio-Acevedo, B.E.; Buendia-Gonzalez, L.; Volke-Sepulveda, T. Tolerance, arsenic uptake, and oxidative stress in Acacia farnesiana under arsenate-stress. Int. J. Phytoremediat. 2016, 18, 671–678. [Google Scholar] [CrossRef] [PubMed]
  39. Chen, H.; Cutright, T.J. The interactive effects of chelator, fertilizer, and rhizobacteria for enhancing phytoremediation of heavy metal contaminated soil. J. Soils Sediments 2002, 2, 203–210. [Google Scholar] [CrossRef]
  40. Ent, A.; Baker, A.J.M.; Reeves, R.D.; Pollard, A.J.; Schat, H. Hyperaccumulators of metal and metalloid trace elements: Facts and fiction. Plant Soil 2013, 362, 319–334. [Google Scholar]
  41. Kirkham, M.B. Cadmium in plants on polluted soils: Effects of soil factors, hyperaccumulation, and amendments. Geoderma 2006, 137, 19–32. [Google Scholar] [CrossRef]
  42. Han, R.; Zhou, B.; Huang, Y.; Lu, X.; Li, S.; Li, N. Bibliometric overview of research trends on heavy metal health risks and impacts in 1989–2018. J. Clean. Prod. 2020, 276, 123249. [Google Scholar] [CrossRef]
  43. Zhao, Q.L.; Wen-Ru, L.U. Research Review and Prospect of Soil Heavy Metals Pollution—Bibliometric Analysis Based on Web of Science. Environ. Sci. Technol. 2010, 33, 105–111. [Google Scholar]
  44. Ngah, W.; Teong, L.C.; Hanafiah, M. Adsorption of dyes and heavy metal ions by chitosan composites: A review. Carbohydr. Polym. 2011, 83, 1446–1456. [Google Scholar] [CrossRef]
  45. Lars, J. Hazards of heavy metal contamination. Br. Med. Bull. 2003, 68, 167–182. [Google Scholar]
  46. Eck, N.J.; Waltman, L. Software survey: VOSviewer, a computer program for bibliometric mapping. Scientometrics 2010, 84, 523–538. [Google Scholar] [PubMed] [Green Version]
  47. Garfield, E. From the science of science to Scientometrics visualizing the history of science with HistCite software. J. Informetr. 2009, 3, 173–179. [Google Scholar] [CrossRef] [Green Version]
  48. Chen, C.M. CiteSpace II: Detecting and visualizing emerging trends and transient patterns in scientific literature. J. Am. Soc. Inf. Sci. Technol. 2006, 57, 359–377. [Google Scholar] [CrossRef] [Green Version]
  49. Small, H. Co-citation in the scientific literature: A new measure of the relationship between two documents. J. Am. Soc. Inf. Sci. 1973, 24, 265–269. [Google Scholar] [CrossRef]
  50. Jiang, L.Y.; Yang, X.E.; He, Z.L. Growth response and phytoextraction of copper at different levels in soils by Elsholtzia splendens. Chemosphere 2004, 55, 1179–1187. [Google Scholar] [CrossRef] [PubMed]
  51. Chao, Y.E.; Zhang, M.; Feng, Y.; Yang, X.E.; Islam, E. cDNA-AFLP analysis of inducible gene expression in zinc hyperaccumulator Sedum alfredii Hance under zinc induction. Environ. Exp. Bot. 2010, 68, 107–112. [Google Scholar] [CrossRef]
  52. Chao, Y.E.; Zhang, M.; Tian, S.K.; Lu, L.L.; Yang, X.E. Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie (Sedum alfredii Hance). J. Zhejiang Univ. Sci. B 2008, 9, 243–249. [Google Scholar] [CrossRef] [Green Version]
  53. Chen, B.; Shen, J.G.; Zhang, X.C.; Pan, F.S.; Yang, X.E.; Feng, Y. The Endophytic Bacterium, Sphingomonas SaMR12, Improves the Potential for Zinc Phytoremediation by Its Host, Sedum alfredii. PLoS ONE 2014, 9, e106826. [Google Scholar] [CrossRef] [PubMed]
  54. Guo, W.D.; Liang, J.; Yang, X.E.; Chao, Y.E.; Feng, Y. Response of ATP sulfurylase and serine acetyltransferase towards cadmium in hyperaccumulator Sedum alfredii Hance. J. Zhejiang Univ. Sci. B 2009, 10, 251–257. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  55. Jiang, L.Y.; Yang, X.E.; Shi, W.Y.; Ye, Z.Q.; He, Z.L. Copper uptake and tolerance in two contrasting ecotypes of Elsholtzia argyi. J. Plant Nutr. 2004, 27, 2067–2083. [Google Scholar] [CrossRef]
  56. Jiang, L.Y.; Yang, X.E.; Ye, Z.Q.; Shi, W.Y. Uptake, distribution and accumulation of copper in two ecotypes of Elsholtzia. Pedosphere 2003, 13, 359–366. [Google Scholar]
  57. Jin, X.F.; Yang, X.E.; Islam, E.; Liu, D.; Mahmood, Q.; Li, H.; Li, J.Y. Ultrastructural changes, zinc hyperaccumulation and its relation with antioxidants in two ecotypes of Sedum alfredii Hance. Plant Physiol. Biochem. 2008, 46, 997–1006. [Google Scholar] [CrossRef]
  58. He, B.; Yang, X.E.; Ni, W.Z.; Wei, Y.Z.; Long, X.X.; Ye, Z.Q. Sedum alfredii: A new lead-accumulating ecotype. Acta Bot. Sin. 2002, 44, 1365–1370. [Google Scholar]
  59. Angle, J.S.; Baker, A.J.M.; Whiting, S.N.; Chaney, R.L. Soil moisture effects on uptake of metals by Thlaspi, Alyssum, and Berkheya. Plant Soil 2003, 256, 325–332. [Google Scholar] [CrossRef]
  60. Baker, A.J.M.; Reeves, R.D.; Hajar, A.S.M. Heavy-Metal Accumulation and Tolerance in British Populations of the Metallophyte Thlaspi-Caerulescens J-And-C-Presl (Brassicaceae). New Phytol. 1994, 127, 61–68. [Google Scholar] [CrossRef]
  61. Peterson, L.R.; Trivett, V.; Baker, A.J.M.; Aguiar, C.; Pollard, A.J. Spread of metals through an invertebrate food chain as influenced by a plant that hyperaccumulates nickel. Chemoecology 2003, 13, 103–108. [Google Scholar] [CrossRef]
  62. Angle, J.S.; Chaney, R.L.; Baker, A.J.M.; Li, Y.; Reeves, R.; Volk, V.; Roseberg, R.; Brewer, E.; Burke, S.; Nelkin, J. Developing commercial phytoextraction technologies: Practical considerations. S. Afr. J. Sci. 2001, 97, 619–623. [Google Scholar]
  63. Fernando, D.R.; Bakkaus, E.J.; Perrier, N.; Baker, A.J.M.; Woodrow, I.E.; Batianoff, G.N.; Collins, R.N. Manganese accumulation in the leaf mesophyll of four tree species: A PIXE/EDAX localization study. New Phytol. 2006, 171, 751–758. [Google Scholar] [CrossRef] [PubMed]
  64. Broadley, M.R.; Willey, N.J.; Wilkins, J.C.; Baker, A.J.M.; Mead, A.; White, P.J. Phylogenetic variation in heavy metal accumulation in angiosperms. New Phytol. 2001, 152, 9–27. [Google Scholar] [CrossRef]
  65. Baker, A.J.M.; McGrath, S.P.; Sidoli, C.M.D.; Reeves, R.D. The Possibility of in-Situ Heavy-Metal Decontamination of Polluted Soils Using Crops of Metal-Accumulating Plants. Resour. Conserv. Recycl. 1994, 11, 41–49. [Google Scholar] [CrossRef]
  66. Salt, D.E.; Blaylock, M.; Kumar, N.; Dushenkov, V.; Ensley, B.D.; Chet, I.; Raskin, I. Phytoremediation—A Novel Strategy for the Removal of Toxic Metals from the Environment Using Plants. Nat. Biotechnol. 1995, 13, 468–474. [Google Scholar] [CrossRef]
  67. Kumar, P.; Dushenkov, V.; Motto, H.; Raskin, I. Phytoextraction—The Use of Plants to Remove Heavy-Metals from Soils. Environ. Sci. Technol. 1995, 29, 1232–1238. [Google Scholar] [CrossRef]
  68. Cunningham, S.D.; Berti, W.R.; Huang, J.W.W. Phytoremediation of Contaminated Soils. Trends Biotechnol. 1995, 13, 393–397. [Google Scholar] [CrossRef]
  69. Pence, N.S.; Larsen, P.B.; Ebbs, S.D.; Letham, D.L.D.; Lasat, M.M.; Garvin, D.F.; Eide, D.; Kochian, L.V. The molecular physiology of heavy metal transport in the Zn/Cd hyperaccumulator Thlaspi caerulescens. Proc. Natl. Acad. Sci. USA 2000, 97, 4956–4960. [Google Scholar] [CrossRef] [Green Version]
  70. Clemens, S. Molecular mechanisms of plant metal tolerance and homeostasis. Planta 2001, 212, 475–486. [Google Scholar] [CrossRef]
  71. Verbruggen, N.; Hermans, C.; Schat, H. Molecular mechanisms of metal hyperaccumulation in plants. New Phytol. 2009, 181, 759–776. [Google Scholar] [CrossRef]
  72. Gerhardt, K.E.; Huang, X.D.; Glick, B.R.; Greenberg, B.M. Phytoremediation and rhizoremediation of organic soil contaminants: Potential and challenges. Plant Sci. 2009, 176, 20–30. [Google Scholar] [CrossRef]
  73. Ma, L.Q.; Komar, K.M.; Tu, C.; Zhang, W.H.; Cai, Y.; Kennelley, E.D. A fern that hyperaccumulates arsenic—A hardy, versatile, fast-growing plant helps to remove arsenic from contaminated soils. Nature 2001, 409, 579. [Google Scholar] [CrossRef]
  74. Yang, X.E.; Long, X.X.; Ye, H.B.; He, Z.L.; Calvert, D.V.; Stoffella, P.J. Cadmium tolerance and hyperaccumulation in a new Zn-hyperaccumulating plant species (Sedum alfredii Hance). Plant Soil 2004, 259, 181–189. [Google Scholar] [CrossRef]
  75. Kupper, H.; Lombi, E.; Zhao, F.J.; McGrath, S.P. Cellular compartmentation of cadmium and zinc in relation to other elements in the hyperaccumulator Arabidopsis halleri. Planta 2000, 212, 75–84. [Google Scholar] [CrossRef] [Green Version]
  76. Garbisu, C.; Alkorta, I. Phytoextraction: A cost-effective plant-based technology for the removal of metals from the environment. Bioresour. Technol. 2001, 77, 229–236. [Google Scholar] [CrossRef]
  77. Begonia, G.B.; Davis, C.D.; Begonia, M.F.T.; Gray, C.N. Growth responses of Indian mustard Brassica juncea (L.) Czern. and its phytoextraction of lead from a contaminated soil. Bull. Environ. Contam. Toxicol. 1998, 61, 38–43. [Google Scholar] [CrossRef]
  78. Brennan, M.A.; Shelley, M.L. A model of the uptake, translocation, and accumulation of lead (Pb) by maize for the purpose of phytoextraction. Ecol. Eng. 1999, 12, 271–297. [Google Scholar] [CrossRef]
  79. Schwartz, C.; Guimont, S.; Saison, C.; Perronnet, K.; Morel, J.L. Phytoextraction of Cd and Zn by the hyperaccumulator plant Thlaspi caerulescens as affected by plant size and origin. S. Afr. J. Sci. 2001, 97, 561–564. [Google Scholar]
  80. Kramer, U.; CotterHowells, J.D.; Charnock, J.M.; Baker, A.J.M.; Smith, J.A.C. Free histidine as a metal chelator in plants that accumulate nickel. Nature 1996, 379, 635–638. [Google Scholar] [CrossRef]
  81. Huang, J.W.W.; Chen, J.J.; Berti, W.R.; Cunningham, S.D. Phytoremediation of lead-contaminated soils: Role of synthetic chelates in lead phytoextraction. Environ. Sci. Technol. 1997, 31, 800–805. [Google Scholar] [CrossRef]
  82. Blaylock, M.J.; Salt, D.E.; Dushenkov, S.; Zakharova, O.; Gussman, C.; Kapulnik, Y.; Ensley, B.D.; Raskin, I. Enhanced accumulation of Pb in Indian mustard by soil-applied chelating agents. Environ. Sci. Technol. 1997, 31, 860–865. [Google Scholar] [CrossRef]
  83. Raskin, I.; Smith, R.D.; Salt, D.E. Phytoremediation of metals: Using plants to remove pollutants from the environment. Curr. Opin. Biotechnol. 1997, 8, 221–226. [Google Scholar] [CrossRef]
  84. Chaney, R.L.; Malik, M.; Li, Y.M.; Brown, S.L.; Brewer, E.P.; Angle, J.S.; Baker, A.J.M. Phytoremediation of soil metals. Curr. Opin. Biotechnol. 1997, 8, 279–284. [Google Scholar] [CrossRef]
  85. Salt, D.E.; Smith, R.D.; Raskin, I. Phytoremediation. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1998, 49, 643–668. [Google Scholar] [CrossRef]
  86. Lombi, E.; Zhao, F.J.; Dunham, S.J.; McGrath, S.P. Phytoremediation of heavy metal-contaminated soils: Natural hyperaccumulation versus chemically enhanced phytoextraction. J. Environ. Qual. 2001, 30, 1919–1926. [Google Scholar] [CrossRef] [PubMed]
  87. Fuhrmann, M.; Lasat, M.M.; Ebbs, S.D.; Kochian, L.V.; Cornish, J. Uptake of cesium-137 and strontium-90 from contaminated soil by three plant species; application to phytoremediation. J. Environ. Qual. 2002, 31, 904–909. [Google Scholar] [CrossRef]
  88. McGrath, S.P.; Zhao, F.J. Phytoextraction of metals and metalloids from contaminated soils. Curr. Opin. Biotechnol. 2003, 14, 277–282. [Google Scholar] [CrossRef]
  89. Pulford, I.D.; Watson, C. Phytoremediation of heavy metal-contaminated land by trees—A review. Environ. Int. 2003, 29, 529–540. [Google Scholar] [CrossRef]
  90. Luo, C.L.; Shen, Z.G.; Li, X.D. Enhanced phytoextraction of Cu, Pb, Zn and Cd with EDTA and EDDS. Chemosphere 2005, 59, 1–11. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  91. Yoon, J.; Cao, X.D.; Zhou, Q.X.; Ma, L.Q. Accumulation of Pb, Cu, and Zn in native plants growing on a contaminated Florida site. Sci. Total Environ. 2006, 368, 456–464. [Google Scholar] [CrossRef]
  92. Clemens, S. Toxic metal accumulation, responses to exposure and mechanisms of tolerance in plants. Biochimie 2006, 88, 1707–1719. [Google Scholar] [CrossRef] [PubMed]
  93. Vangronsveld, J.; Herzig, R.; Weyens, N.; Boulet, J.; Adriaensen, K.; Ruttens, A.; Thewys, T.; Vassilev, A.; Meers, E.; Nehnevajova, E.; et al. Phytoremediation of contaminated soils and groundwater: Lessons from the field. Environ. Sci. Pollut. Res. 2009, 16, 765–794. [Google Scholar] [CrossRef]
  94. Kramer, U. Metal Hyperaccumulation in Plants. In Annual Review of Plant Biology; Merchant, S., Briggs, W.R., Ort, D., Eds.; Annual Reviews: Palo Alto, CA, USA, 2010; Volume 61, pp. 517–534. [Google Scholar]
  95. Adamidis, G.C.; Aloupi, M.; Kazakou, E.; Dimitrakopoulos, P.G. Intra-specific variation in Ni tolerance, accumulation and translocation patterns in the Ni-hyperaccumulator Alyssum lesbiacum. Chemosphere 2014, 95, 496–502. [Google Scholar] [CrossRef] [PubMed]
  96. Isaure, M.P.; Huguet, S.; Meyer, C.L.; Castillo-Michel, H.; Testemale, D.; Vantelon, D.; Saumitou-Laprade, P.; Verbruggen, N.; Sarret, G. Evidence of various mechanisms of Cd sequestration in the hyperaccumulator Arabidopsis halleri, the non-accumulator Arabidopsis lyrata, and their progenies by combined synchrotron-based techniques. J. Exp. Bot. 2015, 66, 3201–3214. [Google Scholar] [CrossRef]
  97. An, Z.Z.; Huang, Z.C.; Lei, M.; Liao, X.Y.; Zheng, Y.M.; Chen, T.B. Zinc tolerance and accumulation in Pteris vittata L. and its potential for phytoremediation of Zn- and As-contaminated soil. Chemosphere 2006, 62, 796–802. [Google Scholar] [CrossRef]
  98. Sarret, G.; Saumitou-Laprade, P.; Bert, V.; Proux, O.; Hazemann, J.L.; Traverse, A.S.; Marcus, M.A.; Manceau, A. Forms of zinc accumulated in the hyperaccumulator Arabidopsis halleri. Plant Physiol. 2002, 130, 1815–1826. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  99. Chen, L.; Luo, S.L.; Li, X.J.; Wan, Y.; Chen, J.L.; Liu, C.B. Interaction of Cd-hyperaccumulator Solanum nigrum L. and functional endophyte Pseudomonas sp Lk9 on soil heavy metals uptake. Soil Biol. Biochem. 2014, 68, 300–308. [Google Scholar] [CrossRef]
  100. Abdel-Wahab, D.A.; Othman, N.; Hamada, A.M. Effects of copper oxide nanoparticles to Solanum nigrum and its potential for phytoremediation. Plant Cell Tissue Organ Cult. 2019, 137, 525–539. [Google Scholar] [CrossRef]
  101. Li, Z.; Wu, L.H.; Hu, P.J.; Luo, Y.M.; Christie, P. Copper changes the yield and cadmium/zinc accumulation and cellular distribution in the cadmium/zinc hyperaccumulator Sedum plumbizincicola. J. Hazard. Mater. 2013, 261, 332–341. [Google Scholar] [CrossRef]
  102. Ghazaryan, K.; Movsesyan, H.; Ghazaryan, N.; Watts, B.A. Copper phytoremediation potential of wild plant species growing in the mine polluted areas of Armenia. Environ. Pollut. 2019, 249, 491–501. [Google Scholar] [CrossRef]
  103. Freitas, F.; Lunardi, S.; Souza, L.B.; von der Osten, J.S.C.; Arruda, R.; Andrade, R.L.T.; Battirola, L.D. Accumulation of copper by the aquatic macrophyte Salvinia biloba Raddi (Salviniaceae). Braz. J. Biol. 2018, 78, 133–139. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  104. Wojcik, M.; Vangronsveld, J.; Tukiendorf, A. Cadmium tolerance in Thlaspi caerulescens—I. Growth parameters, metal accumulation and phytochelatin synthesis in response to cadmium. Environ. Exp. Bot. 2005, 53, 151–161. [Google Scholar] [CrossRef]
  105. Banasova, V.; Horak, O.; Nadubinska, M.; Ciamporova, M.; Lichtscheidl, I. Heavy metal content in Thlaspi caerulescens J. et C. Presl growing on metalliferous and non-metalliferous soils in Central Slovakia. Int. J. Environ. Pollut. 2008, 33, 133–145. [Google Scholar] [CrossRef]
  106. Famulari, S.; Witz, K. A User-Friendly Phytoremediation Database: Creating the Searchable Database, the Users, and the Broader Implications. Int. J. Phytoremediat. 2015, 17, 737–744. [Google Scholar] [CrossRef]
Agronomy 11 01729 g001 550
Figure 1. (a) Annual publications on the topic of hyperaccumulators remediation of potential toxic element (PTE) pollution based on data from Science Citation Index Expanded (Sci-Expanded) database of the Web of Science Core Collection (WoSCC) and document types; (b) percentages of publications for Web of Science categories.
Figure 1. (a) Annual publications on the topic of hyperaccumulators remediation of potential toxic element (PTE) pollution based on data from Science Citation Index Expanded (Sci-Expanded) database of the Web of Science Core Collection (WoSCC) and document types; (b) percentages of publications for Web of Science categories.
Agronomy 11 01729 g001
Agronomy 11 01729 g002 550
Figure 2. Co-authorship network map of authors. There are 31 clusters with a total of 1634 links and a total link strength (TLS) of 8122.Larger nodes indicate that the researcher has more publications. Lines connecting clusters indicate a collaboration between the researchers, which is stronger when the line is thicker. Note that this is produced by VOSviewer and the content cannot be modified.
Figure 2. Co-authorship network map of authors. There are 31 clusters with a total of 1634 links and a total link strength (TLS) of 8122.Larger nodes indicate that the researcher has more publications. Lines connecting clusters indicate a collaboration between the researchers, which is stronger when the line is thicker. Note that this is produced by VOSviewer and the content cannot be modified.
Agronomy 11 01729 g002
Agronomy 11 01729 g003 550
Figure 3. World map of publication distribution by country.
Figure 3. World map of publication distribution by country.
Agronomy 11 01729 g003
Agronomy 11 01729 g004 550
Figure 4. Top 10 journals publishing research on phytoremediation.
Figure 4. Top 10 journals publishing research on phytoremediation.
Agronomy 11 01729 g004
Agronomy 11 01729 g005 550
Figure 5. A citation analysis network of the top 30 publications on phytoremediation using HistCite Pro, based on data obtained from the Web of Science Core Collection (WoSCC). On the left is the year, and on the right are publications for the corresponding year. Each circle represents a publication, and the larger the circle, the more citations. The numbers in the circles were given by HistCite Pro. The numbers in the circles and their publications are: 135 [60], 138 [65], 144 [66], 145 [67], 149 [68], 165 [80], 198 [81], 199 [82], 200 [83], 210 [84], 229 [85], 411 [69], 457 [75], 508 [73], 516 [70], 522 [76], 579 [86], 666 [87], 924 [88], 943 [89], 1128 [74], 1429 [90], 1924 [91], 1952 [92], 2998 [71], 3063 [72], 3416 [93], 3484 [94], 4246 [16], and 5661 [8].
Figure 5. A citation analysis network of the top 30 publications on phytoremediation using HistCite Pro, based on data obtained from the Web of Science Core Collection (WoSCC). On the left is the year, and on the right are publications for the corresponding year. Each circle represents a publication, and the larger the circle, the more citations. The numbers in the circles were given by HistCite Pro. The numbers in the circles and their publications are: 135 [60], 138 [65], 144 [66], 145 [67], 149 [68], 165 [80], 198 [81], 199 [82], 200 [83], 210 [84], 229 [85], 411 [69], 457 [75], 508 [73], 516 [70], 522 [76], 579 [86], 666 [87], 924 [88], 943 [89], 1128 [74], 1429 [90], 1924 [91], 1952 [92], 2998 [71], 3063 [72], 3416 [93], 3484 [94], 4246 [16], and 5661 [8].
Agronomy 11 01729 g005
Agronomy 11 01729 g006 550
Figure 6. The density view of keyword co-occurrence. Note that a larger font for a keyword indicates a greater total link strength (TLS). The closer the keywords are to each other, the better the relevance of these topics. Note that this is produced by Vosviewer and the content cannot be modified.
Figure 6. The density view of keyword co-occurrence. Note that a larger font for a keyword indicates a greater total link strength (TLS). The closer the keywords are to each other, the better the relevance of these topics. Note that this is produced by Vosviewer and the content cannot be modified.
Agronomy 11 01729 g006
Agronomy 11 01729 g007 550
Figure 7. Keywords with the strongest citation bursts developed by CiteSpace. Blue indicates the time when keywords appear, and red indicates the time when keywords burst.
Figure 7. Keywords with the strongest citation bursts developed by CiteSpace. Blue indicates the time when keywords appear, and red indicates the time when keywords burst.
Agronomy 11 01729 g007
Table
Table 1. The top 10 organizations and countries in overall strength of publications related to phytoremediation. The number of publications (N), total local citation score (TLCS), total global citation score (TGCS), total number of links (L), and total link strength (TLS) were obtained from the VOSviewer. TGCS/N is the per-article citations.
Table 1. The top 10 organizations and countries in overall strength of publications related to phytoremediation. The number of publications (N), total local citation score (TLCS), total global citation score (TGCS), total number of links (L), and total link strength (TLS) were obtained from the VOSviewer. TGCS/N is the per-article citations.
No.ItemsNTLCSTGCSLTLSTGCS/N
Top 10 organizations
1Chinese Academy of Sciences (China)85510,65124,49118292729
2Zhejiang University (China)344514310,5738227431
3University of Florida (USA)226639112,1426926654
4Nanjing Agricultural University (China)207312264845518031
5Consejo Superior de Investigaciones Científicas (Spain)205198277698721538
6University of Chinese Academy of Sciences (China)18288425105827814
7University of Lorraine (France)159103923996925215
8Sichuan Agricultural University (China)1478461823287112
9The University of Melbourne (Australia)141322669367420949
10Sun Yat-sen University (China)128165535345214328
Top 10 countries
1China355432,53579,94661139722
2USA177237,50190,17665113351
3India105211,22333,4464838432
4France74510,50225,6946278934
5Spain694609120,7885344430
6Italy619737918,4895333630
7Pakistan562621214,4494055926
8Poland543295891684831417
9Australia539782620,8815661739
10United Kingdom53918,31838,6605544272
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Zhang, D.; Dyck, M.; Filipović, L.; Filipović, V.; Lv, J.; He, H. Hyperaccumulators for Potentially Toxic Elements: A Scientometric Analysis. Agronomy 2021, 11, 1729. https://doi.org/10.3390/agronomy11091729

AMA Style

Zhang D, Dyck M, Filipović L, Filipović V, Lv J, He H. Hyperaccumulators for Potentially Toxic Elements: A Scientometric Analysis. Agronomy. 2021; 11(9):1729. https://doi.org/10.3390/agronomy11091729

Chicago/Turabian Style

Zhang, Dongming, Miles Dyck, Lana Filipović, Vilim Filipović, Jialong Lv, and Hailong He. 2021. "Hyperaccumulators for Potentially Toxic Elements: A Scientometric Analysis" Agronomy 11, no. 9: 1729. https://doi.org/10.3390/agronomy11091729

APA Style

Zhang, D., Dyck, M., Filipović, L., Filipović, V., Lv, J., & He, H. (2021). Hyperaccumulators for Potentially Toxic Elements: A Scientometric Analysis. Agronomy, 11(9), 1729. https://doi.org/10.3390/agronomy11091729

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop