The carcinogenic attribute of arsenic (As) has turned the world to focus more on the decontamination and declining the present level of As from the environment especially from the soil and water bodies. Phytoremediation has achieved a status of sustainable and eco-friendly approach of decontaminating pollutants, and in the present study, an attempt has been made to reveal the potential of As remediation by a halophyte plant, Acanthus ilicifolius L. Special attention has given to analyse the morphological, physiological and anatomical modulations in A. ilicifolius, developed in response to altering concentrations of Na₂AsO₄.7H₂O (0, 70, 80 and 90 μM). Growth of A. ilicifolius under As treatments were diminished as assessed from the reduction in leaf area, root length, dry matter accumulation, and tissue water status. However, the plants exhibited a comparatively higher tolerance index (44%) even when grown in the higher concentrations of As (90 μM). Arsenic treatment induced reduction in the photochemical activities as revealed by the pigment content, chlorophyll stability index (CSI) and Chlorophyll a fluorescence parameter. Interestingly, the thickness and diameter of the xylem walls in the leaf as well as root tissues of As treated samples increased upon increasing the As concentration. The adaptive strategies exhibited by A. ilicifolius towards varying concentrations of As is the result of coordinated responses of morpho-physiological and anatomical attributes, which make the plant a promising candidate for As remediation, especially in wetlands.

Arsenic (As) contamination and bioaccumulation are a serious threat to agricultural plants. To address this issue, we checked the efficacy of As tolerant plant growth promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs) and oxalic acid (OA) in Luffa acutangula grown on As rich soil. The selected most As tolerant PGPB i.e Providencia vermicola exhibited plant growth promoting features i.e solubilzation of phosphate, potassium and siderophores production. Innovatively, we observed the synergistic effects of P. vermicola, ZnO NPs (10 ppm) and OA (100 ppm) in L. acutangula grown on As enriched soil (150 ppm). Our treatments both as alone and in combination alleviated As toxicity exhibited by better plant growth and metabolism. Results revealed significantly enhanced photosynthetic pigments, proline, relative water content, total sugars, proteins and indole acetic acid along with As amelioration in L. acutangula. Furthermore, upregulated plant resistance was manifested with marked reduction in the lipid peroxidation and electrolyte leakage and pronounced antagonism of As and zinc content in leaves under toxic conditions. These treatments also improved level of nutrients, abscisic acid and antioxidants to mitigate As toxicity. This marked improvement in plants’ defense mechanism of treated plants under As stress is confirmed by less damaged leaves cell structures observed through the scanning electron micrographs. We also found substantial decrease in the As bioaccumulation in the L. acutangula shoots and roots by 40 and 58% respectively under the co-application of P. vermicola, ZnO NPs and OA in comparison with control. Moreover, the better activity of soil phosphatase and invertase was assessed under the effect of our application. These results cast a new light on the application of P. vermicola, ZnO NPs and OA in both separate and combined form as a feasible and ecofriendly tool to alleviate As stress in L. acutangula.

Particulate matter (PM) pollution is an urgent urban environmental problem. However, plants can mitigate this pollution by filtering the air. Combining the PM capture capacity with the air pollution tolerance could be better evaluate the suitability of greenbelt plants. We selected nine dominant roadside plants growing at two sites in Beijing, and compared their PM capture capacity, morphological characteristics, biochemical characteristics, and air pollution tolerance index (APTI). Sophora japonica had the highest PM capture capacity (362.98 μg cm⁻²), and its wax layers could trap large amounts of PM₂.₅; this high efficiency is important for successful phytoremediation. Sophora japonica. Sabina chinensis, Ulmus pumila, and Euonymus japonicus also showed relatively high PM capture capacity. This is due to their complex cuticular wax layers, short petioles, rough surfaces, high stomata density, and dense canopy structures which reduce the possibility of resuspension of captured PM. Amount of PM captured per unit leaf area had a significant positive effect on the degree of membrane lipid peroxidation, indicating that species with high PM capture capacity suffered higher oxidative stresses. Air pollution showed the strongest negative effect size on chlorophyll contents of E. japonicas. While, S. japonica, S. chinensis, and U. pumila could prevent chlorophyll content decline under severe oxidative stress. Sophora japonica also had the highest APTI at both sites, indicating this species had the greatest tolerance to air pollution. Our findings suggest that S. japonica would be the most suitable species for greenbelt construction in Beijing, followed by S. chinensis, E. japonicus, and U. pumila.

Air pollution has been identified as a major cause of environmental and human health damage. O₃ is an oxidative pollutant that causes leaf symptoms in sensitive plants. This study aims to adjust a multilinear model for the monitoring of O₃ in subtropical climatic conditions by associating O₃ concentrations with measurements of morphological leaf traits in tobacco plants and different environmental variables. The plants were distributed into five areas (residential, urban or industrial) in the southern region of Brazil and exposed during 14 periods, of 14 days each, during the years of 2014 and 2015. The environmental variables and leaf traits during the exposure periods were described by mean, median, standard deviation and minimum and maximum values. Spearman correlation and multiple linear regression analyses were applied on data from exposure periods. Leaf injury index, leaf area, leaf dry mass, temperature, relative humidity, global solar radiation and accumulated rainfall were used in the regression analyses to select the best models for predicting O₃ concentrations. Leaf injury characteristically caused by O₃ was verified in all areas and periods of plant exposure. Higher values of leaf injury (24.5% and 27.7%) were registered in the 13th and 12th exposure periods during spring and in areas influenced by urban and industrial clutches. The VPD, temperature, global solar radiation and O₃ were correlated to leaf injury. Environmental variables [leaf area, leaf dry mass, global solar radiation and accumulated rainfall] and primarily the VPD were fundamental to improve the adjustments done in the bioindicator model (R² ≥ 0.73). Our research shows that biomonitoring employing the tobacco “Bel-W3” can be improved by measuring morphological leaf traits and meteorological parameters. Additionally, O₃ fumigation experiment should be performed with biomonitoring as conducted in this study, which are useful in understanding the role of other environmental factors.

To assess the potential contribution of nitric oxide (NO) emission from the plants grown under the increasing nitrogen (N) deposition to atmospheric NO budget, the effects of simulated N deposition on NO emission and various leaf traits (e.g., specific leaf area, leaf N concentration, net photosynthetic rate, etc.) were investigated in 79 plant species classified by 13 plant functional groups. Simulated N deposition induced the significant increase of NO emission from most functional groups, especially from conifer, gymnosperm and C₃ herb. Moreover, the change rate of NO emission was significantly correlated with the change rate of various leaf traits. We conclude that the plants grown under atmospheric N deposition, especially in conifer, gymnosperm and C₃ herb, should be taken into account as an important biological source of NO and potentially contribute to atmospheric NO budget.

As particulate matter and heavy metals in the atmosphere affect the atmospheric quality, they pose a threat to human health through the respiratory system. Vegetation can remove airborne particles and purify the atmosphere. Plant leaves are capable of effectively absorbing heavy metals contained by particulates. To evaluate the effects of different garden plants on the particulate matter retention and heavy metal accumulation, the seasonal changes of dust retention of five typical garden plants were compared in the industrial and non-industrial zones in Hangzhou. Results revealed that these species differed in dust retention with the descending order of Loropetalum chinense > Osmanthus fragrans > Pittosporum tobira > Photinia × fraseri > Cinnamomum camphora, which were related to the microstructure feature of the leaf. These species also showed seasonal variation in dust retention, with the highest in summer, followed by winter, autumn, and spring, respectively. The total suspended particle per unit leaf area was higher in the industrial site (80.54 g m⁻²) than in the non-industrial site (19.77 g m⁻²). Leaf particles in different size fractions differed among species, while coarse particles (d > ten μm) predominated in most cases. The L. chinense and C. camphora plants accumulated the greatest Pb and Ni compared to other plants. Overall, L. chinense was the best suitable plant species to improve the air quality.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5–2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles’ effects on different stages of crops and soil quality.

Currently, there is a lack of information about the influence of foliar-applied nanoplastics on crop growth and nutritional quality. To fill the knowledge gap, soil-grown lettuces (Lactuca sativa L.) were foliar-exposed to polystyrene nanoplastics (PSNPs) at 0, 0.1 and 1 mg/L for one month. Foliar exposure to PSNPs significantly decreased the dry weight, height, and leaf area of lettuce by 14.3%–27.3%, 24.2%–27.3%, and 12.7%–19.2%, respectively, compared with the control. Similarly, plant pigment content (chlorophyll a, b and carotenoid) was considerably reduced (9.1%, 8.7%, 12.5%) at 1 mg/L PSNPs. However, the significant increase in electrolyte leakage rate (18.6%–25.5%) and the decrease in total antioxidant capacity (12.4%–26%) were the key indicators of oxidative stress in lettuce leaves, demonstrating the phytotoxicity of PSNPs by foliar exposure. In addition, the remarkable reduction in micronutrients and essential amino acids demonstrated a decrease in nutritional quality of lettuce caused by PSNPs. Besides, SEM and TEM analysis indicated the possible absorption of PSNPs through leaves stoma and the translocation downwards to plant roots. This study provides new information about the interaction of airborne NPs with plants. It also warns against atmospheric NPs pollution that the adverse effects of airborne NPs on crop production and food quality should be assessed as a matter of urgency.

Particulate matter (PM) pollution is a serious environmental problem in most of the cities in the Yangtze River Delta region. Plants can effectively filter ambient air by adsorbing PM. However, only a few studies have paid attention to the dynamic changes and seasonal differences in particle retention capacities of plants under long-term pollution. In this study, we investigated the dynamic changes in particle retention capabilities of the evergreen, broad-leaved, greening plants—Euonymus japonicus var. aurea-marginatus and Pittosporum tobira—in spring and summer. We employed an open-top chamber to simulate the severity of the tail gas pollution. The results showed that, both the plants reached a saturated state in 18–21 days, under continuous exposure to pollution (daily concentration of PM₂.₅: 214.64 ± 321.33 μg·cm⁻³). This was 6–8 days longer than that in the field experiments. In spring, the maximum retention of total particulate matter per unit leaf area of E. japonicus var. aurea-marginatus and P. tobira was 188.47 ± 3.72 μg cm⁻² (18 days) and 67.63 ± 2.86 μg cm⁻² (21 days), respectively. In summer, E. japonicus var. aurea-marginatus and P. tobira reached the maximum retention of the particle on the 21st day, with a net increase of 94.10 ± 3.77 μg cm⁻² and 27.81 ± 3.57 μg cm⁻², respectively. Irrespective of season, the particle retention capacity of E. japonicus var. aurea-marginatus was higher than that of P. tobira, and it showed a better effect on reducing the concentration of fine particles in the atmosphere. The particle retention of the two plants was higher in spring than that in summer. E. japonicus var. aurea-marginatus displayed a significant difference in particle retention between the seasons, while P. tobira did not show much difference. These results will provide a foundation for future studies on the dynamic changes and mechanism of particle retention in plants and management practices by employing plants for particle retention in severely polluted areas.

Urban trees have been assumed to effectively clean air particulate matter (PM), while the inter-species differences are not yet well defined, especially the PM chemical composition. In this study, PM from leaf surface and wax layer of 3 evergreen tree species (Juniper: Juniperus rigida; Black pine: Pinus tabuliformis var. mukdeais; Spruce: Picea koraiensis) were used for finding differences in PM adsorption and its compositional traits (characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrum and Inductively coupled plasma-optical emission spectrometry). Possible improvement in PM removal was also evaluated by a detail whole city tree census and different scenarios of species adjustment data. We found that: 1) the amount of PM on juniper leaves was 5.73 g m−2, 2–2.5-fold higher than black pine and spruce (p < 0.05). Of them, 38.73%, 38.22%, and 23.11% were in the wax layer. 2) Compared with the explicit interspecies differences in PM quantity, more complex interspecies difference showed different patterns for different compositional traits. In general, leaf surface PM had higher O, Si, Al, Fe, N, Pb, Cu, Ni, Cr, and Cd, while the wax PM had higher C and Na contents (p < 0.05). 3) Association ordination found that the smaller leaf size, lower leaf water content, higher leaf area per unit mass, higher wax content, and larger stomatal openness aligned with the more PM adsorption by leaf, together with the higher amounts of CO stretching, O, Si, Al, N, heavy metals of Pb, Cu, Ni, Cr, and Cd in PM. 4) Compared with the other 2 species, increase of juniper percentage in urban forests is more effective for maximizing PM removal from air, accompanying more heavy metal removal but less crystalized minerals in PM. Our findings highlight that proper species configuration in urban afforestation could maximize the air PM removal capacity.