Contamination levels of copper (Cu) and other heavy metals are very high in the soils of the abandoned copper mine of Lasail in the north western Hajar Mountains of Oman. Environment-friendly approaches such as phytoremediation are needed to clean and rehabilitate these areas to their natural status. In the present study, the phytoremediation potential of castor, Ricinus communis L., was evaluated for copper and other heavy metals by growing it in different types of Cu-mine soils and slags. Growth parameters such as shoot height and biomass weight (fresh and dry) were evaluated. Castor showed a high tolerance index (TI) in Cu-mine soils. The highest TI was calculated for the fresh mass of castor shoots in E soil with a percentage of 405.99. The translocation factor (TF) of all the metals except boron (B) and manganese (Mn) was < 1, which reveals that these metals are stabilised in the root portion of the castor. Bioconcentration factor (BCF) value < 1 for Cu indicates that castor is not a hyperaccumulator plant for copper. In addition to high concentrations of copper, other heavy metals such as arsenic (As), iron (Fe), and zinc (Zn) were observed in the roots than in shoots. Castor grown in slag accumulated Cu in the shoots, roots, and entire plant with the values of 25, 1184, and 1209 mg kg⁻¹, respectively. Similarly, castor cultivated in A soil accumulated 18, 901, and 919 mg kg⁻¹ of copper in shoots, roots, and entire plant, respectively. The calculated plant effective number (PENt) indicated the need for 253 castor plants to remove 1 g of Cu from E soil. The ability of castor to grow well in Cu-mine soils suggests that it can be used for the removal of Cu and other heavy metals. Additionally, the shoot portion could potentially be used for oil production since the phytoaccumulation levels of heavy metal concentration in the shoots were below the standard toxicity limits.

Insecticidal crystal (Cry) proteins produced by genetically modified rice that enter the soil via pollen dispersal, plant residues, and root exudation may disturb soil health. In the present study, we assessed the influences of transgenic Bt rice (i.e., HH1 with Cry1Ab/Cry1Ac) cultivation on the dynamics of soil carbon and nutrients under field conditions during 2013–2016. Transgenic treatments (transgenic Bt rice vs. its parental line (i.e., MH63) of non-Bt rice) have no consistently significant effects on soil property, including available nitrogen, available phosphorus, available potassium, total nitrogen, and total phosphorus, while apparent seasonal changes were observed. Besides, the variations of soil nutrients in the paddy field of transgenic Bt rice did not exceed their resistance capacities, except total organic carbon (TOC; RS (resistance) = 1.51) and total potassium (TK; RS = 2.62) in 2013 and TK (RS = 1.94) in 2014. However, the TOC and soil nutrient of TK in the paddy field of transgenic Bt rice have recovered to the pre-perturbation status after harvest (RL (resilience) = 1.01, F = 0.01, P = 0.91; RL = 0.98, F = 0.34, P = 0.58; RL = 0.99, F = 1.26, P = 0.29). Moreover, the paddy yield of transgenic Bt rice was consistently higher than that of its parental line of non-Bt rice. These results suggested that the cultivation of transgenic Bt rice has no adverse impact on soil stability in terms of soil carbon and nutrients and paddy yield.

The air quality decrease, especially in urban areas, is related to local-scale conditions and to dispersion of air pollutants (regional and long-range) as well. The main objective of this study was to decipher the seasonal variation of PM₁₀, NO, NO₂, NOₓ, SO₂, O₃, and CO over a 1-year period (2017) and the possible relationships between air pollution and meteorological variables. Furthermore, trajectory cluster analysis and concentration-weighted trajectory (CWT) methods were used to assess the trajectories and the source-receptor relationship of PM₁₀ in the Ciuc basin Transylvania, known as the “Cold Pole” of Romania. The pollutants show lower concentrations during warmer periods, especially during summer, and significantly higher concentrations were observed on heating season in winter due to seasonal variations in energy use (biomass burning) and atmospheric stability. Subsequently, in February, the highest concentration of PM₁₀ was 132 μg/m³, which is 4 times higher than the highest recorded monthly mean. Our results indicate a negative correlation between CO/temperature (− 0.89), NOₓ/temperature (− 0.84) and positive between NOₓ/PM₁₀ (0.95), CO/PM₁₀ (0.9), and NOₓ/CO (0.98), respectively. Dominant transport pathways were identified and the results revealed that slow-moving southerly (~ 45%) and northwesterly (~ 32%) air masses represent almost 80% and mainly regional flows were discerned. During 2017, increased PM₁₀ levels were measured at the study site when air masses arrived mostly from northwest and southeast. The CWT and polarplot models show a strong seasonal variation and significant differences were observed between weekdays and weekends, namely highest PM₁₀ concentrations during weekends at low wind speed (2–4 m/s).

Using the panel data of China’s provinces from 2005 to 2016, the paper adopts the ultra-efficiency model to measure the green economy efficiency of each province. Then, the paper used the panel threshold model to study the impact of science and technological input on the green economy efficiency with the energy consumption intensity as a threshold variable. The results show that the green economy efficiency in China’s provinces is low and is in a downward trend. When the energy consumption intensity is the threshold variable, the single-threshold effect is significant. When the energy consumption intensity is lower than the threshold value, the impact of science and technological input on green economic efficiency is not significant, and the energy consumption intensity has a significant impact on green economic efficiency with science and technological input and energy consumption intensity as the core explanatory variables and with energy consumption intensity as the threshold variable. When the energy consumption intensity crosses the threshold value, the impact of science and technological input and energy consumption intensity on green economic efficiency becomes significant. According to the above empirical results, this paper proposes corresponding countermeasures and suggestions.

Plants provide many ecosystem services in urban environments, including improving ambient air quality. Leaves of plants permit the deposition of particulate matter (PM) and, depending on their leaf traits, PM may be immobilized within the epicuticular wax (EW) layer, on trichomes, on hyphae of fungi, or inside stomatal cavities. In this study, leaves of 96 perennial urban plant species consisting of 45 deciduous broadleaf/needle-like trees, 32 deciduous broadleaf shrubs, 12 evergreen needle/scale-like trees, 5 evergreen broadleaf trees, and 2 climber species were investigated in June and September 2016 to determine the effectiveness of distinct leaf surfaces in PM immobilization after leaf washing treatment. The leaf surfaces were washed vigorously using a vortex shaker. The magnetizable component of accumulated and immobilized PM on the leaf surfaces was estimated using saturation isothermal remanent magnetization (SIRM) of the unwashed and washed leaves, respectively. In June, the washed leaf SIRM of deciduous (broadleaf/needle-like) tree and shrub species (n = 77) ranged between 0.1 and 13.9 μA. In September, the washed leaf SIRM of all investigated plant species (n = 96) ranged between 1.2 and 35.0 μA. Outcomes of this study indicate that leaves of Buddleja davidii, Viburnum lantana, and Sorbus intermedia showed the highest washed leaf SIRM and thus were the most effective in immobilizing PM on their leaf surfaces while leaves of Populus alba, Robinia pseudoacacia, and Abies fraseri with lowest washed leaf SIRM were the least effective. On average, more than half (i.e., 60%) of the magnetic signal still remained after vigorous washing but a large variation exists between species (9–96%). The leaf SIRM of washed leaves of deciduous broadleaf tree and shrub species was significantly higher compared to leaves of evergreen needle/scale-like species. Evidently, the magnetic signal of unwashed leaves was higher than washed ones and higher in September than in June. Leaf traits significantly influenced the magnetic signal of both washed and unwashed leaves: leaves with a high trichome density or high leaf wettability showed a higher unwashed and washed leaf SIRM compared to leaves with no trichomes or low leaf wettability. The effect of epicuticular wax structure types on leaf SIRM was indicated to be only marginally significant. Moreover, also the immobilized fraction of PM was significantly affected by trichome density and leaf wettability, thus substantiating that plant species with high trichome density and/or leaf wettability not only accumulate more PM but are also less prone to PM re-suspension than other species. In general, the results also indicate that leaf SIRM of unwashed leaves can be a good indicator to determine the effectiveness of a plant species in PM immobilization. Plant species effective in immobilizing PM on their leaf surfaces may likely improve ambient air quality when planted in urban environments. However, it is vital that leaves of these plant species (i.e., with high PM immobilization abilities) are carefully recycled as they may be polluted.

Groundwater is a major source of drinking water and agricultural water in some regions of the world. However, it contains a high level of ²²⁶Ra that is potentially hazardous to human health and the environment. Normally, the activity concentration of ²²⁶Ra in groundwater is determined to assess the quality of groundwater that can be used as drinking water. There are few studies on the accumulation of ²²⁶Ra in the agricultural soil due to irrigation with groundwater. In this study, levels of ²²⁶Ra were determined on over 60 groundwater samples collected from the public water supply wells in Phu Yen province, Vietnam. Besides assessment of the health risks to population due to drinking groundwater samples, the impact of groundwater irrigation to the maize field in the study area was studied. For this purpose, two chemical fate models were applied and the comparison of their results was performed. Based on the model assessments, we predicted that the present agricultural practices increased the ²²⁶Ra activity concentration in the maize soil, and the level of ²²⁶Ra activity concentration in the topsoil can exceed the recommended level at 11.4 years of the present agricultural practices on the maize soil.

Experiments conducted over a period of 6 weeks using Brassica napus callus cells grown in vitro under Eu(III) or U(VI) stress showed that B. napus cells were able to bioassociate both potentially toxic metals (PTM), 628 nmol Eu/gfᵣₑₛₕ cₑₗₗₛ and 995 nmol U/gfᵣₑₛₕ cₑₗₗₛ. Most of the Eu(III) and U(VI) was found to be enriched in the cell wall fraction. Under high metal stress (200 μM), cells responded with reduced cell viability and growth. Subsequent speciation analyses using both metals as luminescence probes confirmed that B. napus callus cells provided multiple-binding environments for Eu(III) and U(VI). Moreover, two different inner-sphere Eu³⁺ species could be distinguished. For U(VI), a dominant binding by organic and/or inorganic phosphate groups of the plant biomass can be concluded.

The current study was performed to evaluate the antiproliferative and apoptosis-inducing potential of n-hexane fraction from Cassia fistula L. (Caesalpinioideae) fruits. The antiproliferative property of the fraction was determined by MTT assay against cancer cell lines including HeLa, MG-63, IMR-32, and PC-3 with GI₅₀ value of 97.69, 155.2, 143, and 160.2 μg/ml respectively. The fraction was further explored for its apoptotic effect using confocal, SEM, and flow cytometry studies in HeLa cells. It was observed that the treatment of fraction revealed fragmentation of DNA, chromatin condensation, membrane blebbing, and formation of apoptotic bodies in a dose-dependent manner. The fraction also showed a remarkable increase in the level of ROS, mitochondrial depolarization and G₀/G₁ phase cell cycle arrest, and induction in the phosphatidylserine externalization analyzed using Annexin V-FITC/PI double staining assay in HeLa cells. Kaempferol, Ellagic acid, and Epicatechin are the major phytoconstituents present in the fraction as revealed by the HPLC. The treatment of n-hexane fraction showed downregulation in the gene expression of Bcl-2 and upregulation in the expression level of p53, Bad, and caspase-3 genes analyzed using semi-quantitative RT-PCR in HeLa cells. These results suggest that n-hexane fraction from C. fistula inhibited the proliferation of cervical cancer cells efficiently by the induction of apoptosis. Graphical abstract

Wide application of nanoparticles causes considerable environmental, health, and safety problems. However, their potential impact and mechanisms on plant growth are not completely clear. In the present study, the effects of different concentration of copper oxide nanoparticles (nCuO) on seed germination and seedling growth, as well as physiological parameters of Brassica pekinensis L., were investigated. The seeds were exposed to 10-, 100-, and 1000-mg L⁻¹ nCuO suspensions and 0.8-mg L⁻¹ Cu²⁺ released from 1000-mg L⁻¹ nCuO for 7 day. The results showed that nCuO did not affect the germination rate, germination potential, and germination index of B. pekinensis but significantly affected the vitality index. The growth of roots and shoots of B. pekinensis was promoted at 10-mg L⁻¹ nCuO, while they were inhibited under 1000-mg L⁻¹ nCuO and Cu²⁺ ion treatments, and roots suffered more damage than shoots. Cu content in shoots and roots of B. pekinensis increased with increasing concentrations of nCuO, which is significantly higher in roots as compared with shoots. Roots and shoots accumulated more Cu under nCuO treatments compared with Cu²⁺ ion treatment. nCuO treatments led to significant lignification in roots of B. pekinensis. Furthermore, nCuO increased in the contents of soluble sugar and protein in shoots, while nCuO at 1000 mg L⁻¹ significantly inhibited the content of soluble protein in roots. In addition, concentration-dependent augmentation of lipid peroxidation, hydrogen peroxide and superoxide generation, and antioxidant enzyme activity were noticed in shoots and roots of B. pekinensis seedlings under nCuO and Cu²⁺ ion treatments. Altogether, the results strongly suggested that the phytotoxicity of nCuO in B. pekinensis was caused by both the nanoparticles itself and the released Cu²⁺ ions.

Environmental lead (Pb) exposure can induce dysbacteriosis, impair oral health, and is associated with the development of dental caries. However, the mechanism is unclear. The aim of this study was to explore the effects of Pb toxicity on oral antimicrobial activity in children in an e-waste area. Results showed higher blood Pb levels in e-waste-exposed group children, accompanied by decreased saliva SAG (salivary agglutinin) concentrations, increased peripheral WBC (white blood cell) counts and monocyte counts, and elevated peripheral monocyte percentage. LnPb (natural logarithmic transformation of blood Pb level) was negatively correlated with saliva SAG concentration, while positively correlated with peripheral monocyte percentage. Saliva SAG concentration played a complete mediating role in the correlation of LnPb to peripheral monocyte percentage. To our knowledge, this is the first study on the relationship of environmental Pb exposure and oral antimicrobial activity in children, showing that environmental Pb exposure may weaken oral antimicrobial activity through reducing saliva SAG concentration, which may raise the risk of oral dysbacteriosis and ultimately pathogen infection.