Hyperaccumulators for potentially toxic elements: A scientometric analysis

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

Development and application of the heat pulse method for soil physical measurements

Accurate and continuous measurements of soil thermal and hydraulic properties are required for environmental, Earth and planetary science, and engineering applications, but they are not practically obtained by steady‐state methods. The heat pulse (HP) method is a transient method for determination of soil thermal properties and a wide range of other physical properties in laboratory and field conditions. The HP method is based on the line‐heat source solution of the radial heat flow equation. This literature review begins with a discussion of the evolution of the HP method and related applications, followed by the principal theories, data interpretation methods, and their differences. Important factors for HP probe construction are presented. The properties determined in unfrozen and frozen soils are discussed, followed by a discussion of limitations and perspectives for the application of this method. The paper closes with a brief overview of future needs and opportunities for further development and application of the HP method

Role of Bentonite on the Mobility of Antibiotic Resistance Genes, and Microbial Community in Oxytetracycline and Cadmium Contaminated Soil

The effects of bentonite (BT), a commonly used heavy metal deactivator, on the ARGs and microbial communities in soils and lettuce systems contaminated by heavy metals and antibiotics are unclear. A study was conducted to investigate the effect of BT on the mobility of antibiotic resistance genes in oxytetracycline and cadmium contaminated soil. Results showed that the addition of BT reduced the accumulation of OTC and ARGs in the soil and lettuce roots, but increased the abundance of ARGs in lettuce leaves, and increase the risk of human pathogenic bacteria (HPB) transferring to lettuce leaves. Redundancy analysis showed that environmental factors (OTC, H2O, SOM, and pH) were the dominant factors that influence the distribution of ARGs and intI1. Network analysis showed that Proteobacteria and Bacteroidetes were the major host bacteria which caused changes in ARGs and intI1. There were significant positive correlations between ermX and ermQ, and a large number of HPB. The co-occurrence of intl1 with some ARGs (tetC, tetG, ermQ, sul1, and sul2), may threaten human health due to the dispersion of ARGs via horizontal gene transfer

Changes of the adjacent discs and vertebrae in patients with osteoporotic vertebral compression fractures treated with or without bone cement augmentation

Background Context: Although vertebral augmentation with bone cement has been commonly used to treat symptomatic osteoporotic vertebral compression fractures, relatively little is known about the impact of augmentation on the adjacent spinal components. Purpose: To determine the imaging effects of vertebral augmentation on the adjacent discs, the augmented vertebra, and the involved spinal segment. Study Design: Retrospective radiographic study. Patient Sample: Patients with acute osteoporotic vertebral compression fractures who underwent vertebral augmentation or nonoperative treatments. Outcome Measures: On baseline and follow-up mid-sagittal T2W magnetic resonance images, quantitative measurements of disc degeneration, including disc height, bulging, and signal, vertebral height, wedge angle, and segmental kyphotic angle were acquired. Methods: Lumbar spine magnetic resonance images of patients with acute osteoporotic vertebral compression fractures at a local hospital in Eastern China between 2010 and 2017 were reviewed. Student’s t-tests and χ2 tests were used to examine the differences of baseline and changes over time between vertebrae underwent vertebral augmentation and those did not. Paired t-tests were used to examine the differences between baseline and follow-up to study the changes of adjacent disc degeneration, creep deformity of the vertebra and progression of segmental kyphosis. Results: There were 112 acute vertebral compression fractures (72 treated with kyphoplasty and 40 with nonoperative treatments) in 101 subjects. At final follow-up (mean 21.5 months), the cranial disc of the augmented vertebra decreased in height (p<0.001), and both cranial and caudal discs decreased in signal intensity (p≤0.02). The discs in the nonoperative group did not undergo such degenerative changes. For the fractured vertebra, vertebral height significantly decreased (p<0.01 for both) and vertebral wedge angle significantly increased (p≤0.01 for both), regardless of augmentation treatment or not. Segmental kyphotic angle significantly increased in vertebral fractures that underwent vertebral augmentation (p<0.001), but not in those underwent nonoperative treatments. Conclusions: Patients that underwent vertebral augmentation had more advanced disc degeneration at adjacent disc levels as compared to those without augmentation. The fractured vertebral body height decreased and the wedge angle increased, regardless of vertebral augmentation treatment or not. Vertebral augmentation may be associated with increased creep deformity of the adjacent vertebra and the progression of segmental kyphosis

Efficient Phosphate Removal from Wastewater by Ca-Laden Biochar Composites Prepared from Eggshell and Peanut Shells: A Comparison of Methods

Biochar is currently widely used as the adsorbent for phosphorus (P) removal from wastewater. Cheap and green modified materials and efficient preparation methods are the key to obtain efficient and economical engineering biochar. Conventional salt solution and chemical impregnation are common methods for preparing engineered biochar. However, this preparation method is not environmentally friendly or cheap due to the price of salt solutions and the solvent treatment process for chemical impregnation. In this article, Ca-laden biochar was prepared using peanut shells as carbon base materials and discarded eggshells as calcium source. Two methods (ball milling and chemical impregnation) of building the Ca-laden biochar were compared from the perspective of the characterization of biochar, the adsorption performance and the economic cost. The composition and structure of biochar were analyzed by the element content, functional group, X-ray diffraction, energy spectrum and electron microscope scanning etc. The adsorption behavior of biochar was tested in different environments (pH and temperature). The results revealed that the capacity of P adsorption by the Ca-modified biochar was higher than the adsorption by raw biochar, and that the prepared Ca-laden biochar has a wide working environment. Moreover, the Ca-laden biochar prepared by ball milling has a higher specific surface area and more porosity. The Ca-modified biochar through ball milling has a higher amount of adsorbed P than that of through chemical impregnation. This work not only creates a novel method for making excellent P adsorbents, but also offers an environmentally friendly use for agricultural eggshells and peanut shells

Efficient Phosphate Removal from Wastewater by Ca-Laden Biochar Composites Prepared from Eggshell and Peanut Shells: A Comparison of Methods

Biochar is currently widely used as the adsorbent for phosphorus (P) removal from wastewater. Cheap and green modified materials and efficient preparation methods are the key to obtain efficient and economical engineering biochar. Conventional salt solution and chemical impregnation are common methods for preparing engineered biochar. However, this preparation method is not environmentally friendly or cheap due to the price of salt solutions and the solvent treatment process for chemical impregnation. In this article, Ca-laden biochar was prepared using peanut shells as carbon base materials and discarded eggshells as calcium source. Two methods (ball milling and chemical impregnation) of building the Ca-laden biochar were compared from the perspective of the characterization of biochar, the adsorption performance and the economic cost. The composition and structure of biochar were analyzed by the element content, functional group, X-ray diffraction, energy spectrum and electron microscope scanning etc. The adsorption behavior of biochar was tested in different environments (pH and temperature). The results revealed that the capacity of P adsorption by the Ca-modified biochar was higher than the adsorption by raw biochar, and that the prepared Ca-laden biochar has a wide working environment. Moreover, the Ca-laden biochar prepared by ball milling has a higher specific surface area and more porosity. The Ca-modified biochar through ball milling has a higher amount of adsorbed P than that of through chemical impregnation. This work not only creates a novel method for making excellent P adsorbents, but also offers an environmentally friendly use for agricultural eggshells and peanut shells

The Heat Pulse Method for Soil Physical Measurements: A Bibliometric Analysis

Heat pulse method is a transient method that estimates soil thermal properties by characterizing the radial transport of short-duration line-source heat applied to soils. It has been widely used to measure a wide range of soil physical properties including soil thermal conductivity, thermal diffusivity, heat capacity, water content, ice content, bulk density, water flux and evaporation in laboratory and field environments. Previous studies generally focus on the scientific aspects of heat pulse method based on selected publications, and there is a lack of study investigating the heat pulse publication as a whole. The objective of this study was to give an overall view of the use of heat pulse method for soil physical measurements from the bibliometric perspectives. The analyses were based on the Web of Science Core Collection data between 1992 and 2019 using HistCite Pro and VOSviewer. The results showed an increasing trend in the volume of publications on this field and Dr. Robert Horton was the most productive researcher coauthoring papers on the heat pulse method. The co-authorship analysis revealed that researchers from soil science are closely collaborated, but this is not true for researchers in other fields. There is a lack of new young scientists committing to this field while the older generation of researchers are retiring. The United States Department of Agriculture Agricultural Research Servics (USDA-ARS), the China Agriculture University and the Chinese Academy of Science were the top three organizations applying the heat pulse method, while the USA, China and Canada were the top three countries. The Soil Science Society of America Journal, Water Resources Research and Agricultural and Forestry Meteorology were the most widely used journals. The con-occurrence and citation analysis could be used to map the development of the field and identify the most influential publications. The study showed that the bibliometric analysis is a useful tool to visualize research status as well as to provide the general information of novices and experts alike on the heat pulse method for soil physical measurements

Microbial Diversity and Community Structure in Agricultural Soils Suffering from 4-year Pb Contamination

Heavy metal pollution has become a widespread environmental problem due to rapid economic development. The phylogenetic diversity and structure of microbial communities in Pb-contaminated Lou soils were investigated using Illumina MiSeq sequencing of 16S rRNA genes. The presence of Pb2+ in soil showed weak impact on the diversity of soil bacteria community, but influenced the abundance of some genera of bacteria, as well as soil physicochemical properties. We found significant differences in the relative abundances of heavy metal resistant bacteria such as Bacillus, Streptococcus and Arthrobacter at the genus level. Available Pb (APb) and total Pb (TPb) negatively correlated with soil organic matter (SOM), but positively affected available phosphorus (AP). The abundance of main bacteria phyla was highly correlated with total Pb (TPb). The relative abundance of Gemmatimonadetes, Nitrospirae and Planctomycetes were negatively correlated with total Pb (TPb). Collectively, Pb influences both the microbial community composition and physicochemical properties of soil.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

A Scientometric Analysis of Worldwide Intercropping Research Based on Web of Science Database between 1992 and 2020

Intercropping has been practiced worldwide in both traditional and sustainable agriculture to feed the growing population. This study aims to analyze the research status and evolution of intercropping, to identify the influential authors, research centers, and articles, and to reveal the main research topics between 1992 and 2020 based on the Web of Science Core Collection database. The results show that the volume of publications in this field has increased rapidly over the past three decades. The analysis identifies the top three authors (i.e., Meine Van Noordwijk, Wenyu Yang, and Teja Tscharntke), top three contributing organizations (i.e., the World Agroforestry Center (ICRAF), the Chinese Academy of Science, and the INRA), and three most productive countries (i.e., the USA, India, and China). Co-occurrence analysis demonstrates that studies on intercropping can be divided into four clusters as centered by keywords of intercropping/maize, biodiversity/conservation, agroforestry, and carbon, respectively. Lal 2004 is the most influential study with the greatest number of citations and Agroforestry Systems is the most utilized journal. Perspectives on future studies were also given. This study helps researchers to clarify the current research status in the field of intercropping and put forward its future research