In this study, copper oxide nanorods were synthesized via surfactant-assisted chemical precipitation method and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible spectrometer. XRD result reveals that CuO nanorods were structured in the monoclinic phase. SEM image suggested that synthesized CuO were shaped like nanorod with approximately 20–40 nm width and 500–800 nm length. The observed band gap calculated from UV-Visible absorption studies is 1.45 eV. As-prepared CuO nanorods were applied as a photocatalyst for the degradation of textile dye Reactive Black 5 (RB-5) in aqueous solution under the presence of visible light. The result exhibited that an enhanced degradation of RB-5 was achieved around 98% within 300 min and the experimental values were well matched with the linear fit model (R² = 0.97) and the observed rate constant found to be 5 × 10⁻³ min⁻¹. Therefore, as-synthesized CuO nanorods can be applied as a potential photocatalyst material for the degradation of organic pollutants in the wastewater.

Chlordecone, an organochlorine insecticide, was widely used in the French West Indies banana plantations. We set up a cohort of banana plantation workers who worked between 1973 and 1993, the period of authorized use of chlordecone. Vital status and causes of death were collected from French national registries. Workers were followed up from 1 January 2000 to 31 December 2015. Cause-specific mortality in the cohort was compared to that of the general population of the French West Indies by computing standardized mortality ratios (SMRs). A total of 11,112 workers (149,526 person-years, 77% men) were included in the mortality analysis, and 3647 deaths occurred over the study period. There was a slight deficit in all-cause mortality, which was statistically significant in men (SMR = 0.93, 95% CI 0.89–0.96), but not in women (SMR = 0.96, 95% CI 0.89–1.04). All-cancer mortality did not differ significantly from that of the general population (men: SMR = 0.96, 95% CI 0.90–1.03; women: SMR = 1.04, 95% CI 0.89–1.21). Significant excesses of deaths were observed for stomach cancer in women (SMR = 1.94, 95% CI 1.24–2.89) and pancreatic cancer in women farm owners (SMR = 2.31, 95% CI 1.06–4.39). Mortality from prostate cancer was similar to that of the general population in the whole cohort (SMR = 1.00; 95% CI 0.89–1.13) and non-significantly elevated among farm workers (SMR = 1.10, 95% CI 0.87–1.36). Non-significant increases in mortality were also observed for lung cancer in women, leukemia in men, and non-Hodgkin lymphoma in both genders.

This paper investigates the convergence of per capita renewable energy consumption across 15 core EU member countries over the period 1990–2018. In addition to the traditional convergence tests, this paper employs a Lagrange multiplier (LM)–based panel unit root test that allows for two endogenously determined structural breaks to test for the stochastic convergence. Given the shortcomings of stochastic convergence tests in light of the possibility of multiple equilibria associated with groups of countries following different convergence paths, the club convergence algorithm is also employed. Traditional cross-sectional tests indicate that both β- and σ-convergence of per capita renewable energy consumption exist across the EU-15 countries. Moreover, the results of stochastic convergence tests reveal that relative per capita renewable energy consumption is converging across the sampled countries over the sample period. However, the club convergence test results suggest the rejection of full panel club convergence and the presence of a certain number of clubs for the variable of interest.

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.

A series of environmental protective policies have been taken recently in the Pearl River Estuary (PRE) to alleviate water pollution; however, their influence on the reduction of heavy metals in estuarine water has not been known. This study selected Guangzhou as a representative city in the PRE and collected estuarine water monthly from 2008 to 2017 to track the variation of As, Hg, Pb, Cd, Cu, Zn, and Se. During the last decade, the high time-resolved record showed that the concentration of Hg, Pb, Cd, Cu, and Zn in estuarine water reduced by 39.5%, 91.0%, 86.2%, 74.6%, and 97.3%, respectively. However, the concentration of As kept in a stable range (1.89–2.69 μg L⁻¹) and Se (0.17–0.65 μg L⁻¹) increased slightly. The principal component analysis (PCA) and absolute principal component scores-multiple linear regression (APCS-MLR) results suggested that the upstream industrial effluents were major sources for Hg (45.5–92.7%), Pb (47.3–100%), Cd (42.0–90.6%), Cu (85.5–100%), and Zn (100%) and the geogenic source was major origin for As (84.6–98.3%) and Se (0–67.5%). The risk quotient of Hg, Pb, Cd, Cu, and Zn to aquatic organisms largely decreased from 0.03, 0.59, 0.03, 2.06, and 0.26 in 2008 to 0.02, 0.05, 0.006, 0.52, and 0.007 in 2017, respectively. The effective control of heavy metal pollution in the study area can be primarily due to the relocation of hundreds of polluting factories during the last decade.

This study investigated the removal of selenite from wastewater using the fungus Asergillus niger KP isolated from a laboratory scale inverse fluidized bed bioreactor. The effect of different carbon sources and initial selenite concentration on fungal growth, pellet formation and selenite removal was first examined in a batch system. The fungal strain showed a maximum selenite removal efficiency of 86% in the batch system. Analysis of the fungal pellets by field-emission scanning electron microscopy, field-emission transmission electron microscopy and energy-dispersive X-ray spectroscopy revealed the formation of spherical-shaped elemental selenium nanoparticles of size 65–100 nm. An increase in the initial selenite concentration in the media resulted in compact pellets with smooth hyphae structure, whereas the fungal pellets contained hair like hyphae structure when grown in the absence of selenite. Besides, a high initial selenite concentration reduced biomass growth and selenite removal from solution. Using an airlift reactor with fungal pellets, operated under continuous mode, a maximum selenite removal of 94.3% was achieved at 10 mg L⁻¹ of influent selenite concentration and 72 h HRT (hydraulic retention time). Overall, this study demonstrated very good potential of the fungal-pelleted airlift bioreactor system for removal of selenite from wastewater. Graphical abstract

With the rapid industrialization, increasing of fossil fuel consumption and the environmental impact, it is an inevitable trend to develop clean energy and renewable energy. Hydrogen, for its renewable and pollution-free characteristics, has become an important potential energy carrier. Hydrogen is regarded as a promising alternative fuel for fossil fuels in the future. Therefore, it is very necessary to summarize the technological progress in the development of hydrogen energy and research the status and future challenges. Hydrogen production and storage technology are the key problems for hydrogen application. This study applied bibliometric analysis to review the research features and trends of hydrogen production and storage study. Results showed that in the 2004–2018 period, China, USA and Japan leading in these research fields, the research and development in the world have grown rapidly. However, the development of hydrogen energy still faces the challenge of high production cost and high storage requirements. Photocatalytic decomposition of water to hydrogen has attracted more and more research in hydrogen production research, and the development of new hydrogen storage materials has become a key theme in hydrogen storage research. This study provides a comprehensive review of hydrogen production and storage and identifies research progress on future research trend in these fields. It would be helpful for policy-making and technology development and provide suggestions on the development of a hydrogen economy.

The pollution caused by heavy metal ions in industrial wastewater is of a great concern. Applying effective and low-cost methods is an urgent need for treatment of polluted water and aqueous solutions. Biosorption have received the most attention among the various methods. It has become an alternative technique to conventional technologies due to low cost, simple operation and treatment for heavy metal recovery, and high selectivity. In recent years, sea material shells have been applied as one of the most cost-effective bio-adsorbents due to their special properties. They are environmentally friendly, low cost, and easy to access and have high adsorption capacity. The purpose of this review is to present the application of oyster shell, snail shell, and shrimp shell as low-cost and effective biosorbents for removal of noxious heavy metals from aqueous solutions. In addition, heavy metals, their sources, and ways to remediate them from waste streams and various factors affecting the biosorption process with sea materials shells are also reviewed. Moreover, a brief description and literature review of the equilibrium, kinetic, and thermodynamic behaviors of the heavy metal ion adsorption process on sea material shells have been studied. Finally, further applications of sea materials shell for waste effluents treatment are specially focused.

Eutrophication has been a critical environmental issue due to soil nitrogen (N) and phosphorus (P) loss in runoff from agricultural lands. Plant hedgerow is an important measure to prevent soil erosion and reduce agricultural non-point source pollution (NPSP). In the present study, we searched 3683 research papers on plant hedgerows published from 1980 to March 2020. After screening, we used 53 effective papers on plant hedgerows for the meta-analysis by using Stata 15.1. The results showed that plant hedgerows significantly increased soil organic matter (SOM) (standardized mean difference (SMD) = 1.46; 95% confidence interval (CI) = 1.12–1.80 > 0), total N (TN) (SMD = 1.33; 95% CI 0.98–1.68 > 0), total P (SMD = 0.73; 95% CI 0.26–1.20 > 0), alkali N (SMD = 0.86; 95% CI 0.52–1.21 > 0), available P (SMD = 1.28; 95% CI 0.75–1.81 > 0) and readily available potassium (K) (SMD = 1.20; 95% CI 0.75–1.65 > 0) concentrations but exhibited no significant effects on soil total K concentration (SMD = 0.17; 95% CI − 0.13–0.47 < 0). Plant hedgerows showed a greater effect on SOM increase than soil N, P, and K, and soil TN increase than the available state, but the opposite trend was observed for P and K. This meta-analysis can clarify the influence of plant hedgerows on soil nutrients and provide ideas for the prevention and control of agricultural NPSP.

This study was performed to determine the concentrations of copper (Cu), zinc (Zn), and lead (Pb) in the gill, liver, muscle, and tail fin tissues of Euthynnus affinis, Katsuwonus pelamis, and Thunnus albacares from Oman Sea. All samples were analyzed using a flame atomic absorption spectrophotometer and the results were expressed as μg g⁻¹ dry weight. Metal concentrations were significantly higher in the liver than other tissues in three species (with some exceptions) (p < 0.05). The concentrations of metal accumulation in tissues of tuna species followed the Zn > Cu > Pb. Correlation matrix and principal component analysis (PCA) revealed that Zn and Pb have anthropogenic sources. Estimated daily intake (EDI) in three tuna species for heavy metals were below the tolerable daily intake (TDI). Also, the mean target hazard quotient (THQ) based on studied metals in three tuna species was below 1, which suggests that consumption of these fish can be safe for human health in the Oman Sea. Graphical Abstract .