Pollution monitoring using the leaf-deposited particulates and magnetism of the leaves of 23 plant species in a semi-arid city, Northwest China

Optimizing particulate matter removal through rainfall: Role of duration, intensity, and species in green infrastructure

This study investigates how short-duration intense rainfall events enhance the removal of particulate matter (PM) from plant leaf surfaces in urban environments, thereby contributing to the regulation of air pollution in urban environments and advancing the estimation and measurement of ecosystem services modelling in urban green spaces associated with air pollution regulation and remediation. Using controlled artificial rainfall simulations, we identified optimal combinations of rainfall phase (duration), intensity, plant species, plant height above ground (representing the nozzle-to-leaf distance), and particle diameter to maximize PM removal. Our findings indicate that rainfall phase is crucial in the PM removal process, while particle diameter has minimal influence. Throughout all rainfall phases, plant species consistently play a significant role, driven by differences in leaf morphology and microstructure. The study also identifies optimal rainfall conditions for different species, suggesting dynamic adjustments to intensity and nozzle distance throughout the event to enhance PM removal efficiency. For equal rainfall amounts, lower-intensity, longer-duration events are generally more effective, though nozzle distance should align with species-specific preferences. In contrast, higher rainfall intensities (45-60 mm/h) paired with shorter nozzle distances (1 m plant height, 11 m distance) optimize PM removal for fixed rainfall durations. These findings not only identify optimal rainfall conditions for specific species, providing practical strategies for urban green infrastructure management, but also provide valuable insights into estimating the air purification benefits of rainfall-driven PM removal from leaf surfaces.

Monitoring dust retention variations in different functional zones based on leaf magnetism and the influence of green belt spatial layouts on leaf dust retention

Atmospheric particulate pollution generated by traffic activities poses a threat to human health. Due to their unique structure and function, plant leaves efficiently capture and accumulate atmospheric particulate matter, acting as natural particulate collectors. This study focuses on leaf samples from different functional zones in Jinhua City, Zhejiang Province, employing environmental magnetism methods to explore dust retention differences among zones and the impact of green belt spatial layouts on dust retention. The results indicate that leaf magnetism is an effective method for monitoring traffic-related particulate pollution. The saturation isothermal remanent magnetization per unit area (2D-SIRM) values of leaf samples from traffic zones were significantly higher than those from residential areas; the 2D-SIRM value of tree leaves increases with higher traffic volume, indicating more dust retention, suggesting that traffic activities are a major source of particulate pollution. Leaf height (height above the ground), distance from roads, and orientation significantly influence dust retention, with higher magnetic mineral concentrations found in leaves facing roads, closer to roads, and at a height of 2 m, suggesting that traffic-emitted particulates tend to accumulate in these areas. There are differences in dust retention capacities among tree species; Osmanthus and Loropetalum chinense perform better than Golden Privet and Red Tip Photinia. The research results provide some reference for the design of roadside green vegetation systems in Jinhua City and other cities in subtropical monsoon climate zones.

Integrative study of subcellular distribution, chemical forms, and physiological responses for understanding cadmium tolerance in two garden shrubs

Urban ornamental shrubs have significant potential for restoring cadmium (Cd)-contaminated soil. The Cd enrichment characteristics and tolerance mechanisms of Buxus sinica and Ligustrum × vicaryi were investigated through a simulated pot pollution experiment. Specifically, the Cd content and accumulation in different plant tissues, the subcellular distribution and chemical forms of Cd in the roots, and the effects of Cd on the ultrastructure of root cells under various Cd concentrations (0, 25, 50, 100, and 200 mg kg⁻1) were analyzed. The results showed that: (1) As the Cd treatment levels increased, the total biomass of B. sinica gradually decreased, while L. × vicaryi exhibited a stimulation effect at low Cd concentrations but inhibition at high Cd concentrations. (2) The Cd content in different tissues of both shrubs increased with rising Cd levels. The bioconcentration factor (BCF) and translocation factor (TF) indicated that L. × vicaryi has the potential for Cd phytostabilization. (3) Cd in the roots of both shrubs was primarily present in NaCl-extractable form, and was mostly bound to the cell wall. (4) Excessive Cd caused damage to the cellular structure of B. sinica, while the cells of L. × vicaryi maintained normal morphology. (5) In both shrubs, Cd primarily bound to the cell wall through hydroxyl and amino functional groups, as well as soluble sugars. In summary, converting Cd to less active forms, immobilizing Cd in the cell wall, and providing binding sites through functional groups may be crucial resistance mechanisms for both shrubs in response to Cd stress.

Pharmacological and phytochemical properties of the genus Buxus: A review

BACKGROUND

Buxus plants have been used in traditional medicine for a very long time. The Buxus genus has been used to cure a variety of illnesses.

OBJECTIVE

This review aimed to provide a literature review on the genus Buxus including its biological and phytochemical properties.

MATERIALS AND METHODS

The current study was conducted using several scientific databases. Correct plant names were verified from plantlist.org. The results of this search were interpreted, analyzed, and documented based on the obtained bibliographic information.

RESULTS

Within all the species of the family Buxaceae, 5 species of the genus Buxus are reported to be antibacterial, 3 species have been found to be antioxidant, 5 species are cytotoxic, 1 species is anti-inflammatory, 1 species is antidiabetic, and 4 species are antifungal. Alkaloids, terpenoids, tannins, flavonoids, peptides, and phenolic compounds are the main chemical components of this genus. The study of >11 Buxuss pecies has identified >201 compounds. Pharmacological research has demonstrated that crude extracts and some pure compounds obtained from Buxus have several pharmacological activities such as antibacterial, antioxidant, cytotoxic, anti-inflammatory, antidiabetic, and antifungal. Based on the study of the phytochemistry of Buxus species, it was concluded that all the studied plants have active compounds, among which 55 molecules showed interesting activities.

CONCLUSIONS

The numerous traditional uses of Buxus species have been supported by several studies. Before Buxus plants can be fully employed clinically, further research is necessary.

Diversity and negative effect of PM0.3-10.0 adsorbed by needles of urban trees in Irkutsk, Russia

The study was performed in natural forests preserved within the Boreal zone city, Irkutsk, Russia. Test sites were selected in the forests in different districts of the city, where samples of Scots pine (Pinus sylvestris L.) and Siberian larch (Larix sibirica Ledeb.) needles were taken to study the adsorption on their surface of aerosol particles of different sizes, in microns: PM0.3, PM0.5, PM1, PM2.5, PM5, PM10. Scanning electron microscopy was used to obtain high-resolution photographs (magnification 800- × 2000, × 16,000) and aerosol particles (particulate matter-PM) were shown to be intensively adsorbed by the surface of needles, with both size and shape of the particles characterized by a wide variety. Pine needles can be covered with particles of solid aerosol by 50-75%, stomata are often completely blocked. Larch needles often show areas, which are completely covered with aerosol particles, there are often found stomata deformed by the penetration of PMx. X-ray spectral microanalysis showed differences in the chemical composition of adsorbed PMx, the particles can be metallic if metals predominate in their composition, carbonaceous-in case of carbon predominance-or polyelemental if the composition is complex and includes significant quantities of other elements besides metals and carbon (calcium, magnesium, potassium, sodium, sulfur, chlorine, fluorine). Since the particles contain a large proportion of technogenic pollutants, accumulation by the needles of some widespread pollutants was investigated. A direct correlation of a highly significant level between the concentration of PMx in the air and the accumulation of many heavy metals in pine and larch needles, as well as sulfur, fluorine, and chlorine, has been revealed, which indicates a high cleaning capacity of urban forests. At the same time, the negative impact of PMx particles on the vital status of trees is great, which shows in intense disturbance of the parameters of photosynthesis and transpiration, leading to a significant decrease in the growth characteristics of trees and reduction in the photosynthetic volume of the crowns. We consider that the results obtained are instrumental in developing an approach to improvement of urban forests status and creating a comfortable urban environment for the population.

Aerosol Impacts on Water Relations of Camphor (Cinnamomum camphora)

Major parts of anthropogenic and natural aerosols are hygroscopic and deliquesce at high humidity, particularly when depositing to leaf surfaces close to transpiring stomata. Deliquescence and subsequent salt creep may establish thin, extraordinary pathways into the stomata, which foster stomatal uptake of nutrients and water but may also cause stomatal liquid water loss by wicking. Such additional water loss is not accompanied by a wider stomatal aperture with a larger CO₂ influx and hypothetically reduces water use efficiency (WUE). Here, the possible direct impacts of aerosols on physical and physiological parameters of camphor (Cinnamomum camphora) were studied (i) in a greenhouse experiment using aerosol exclusion and (ii) in a field study in Taiwan, comparing trees at two sites with different aerosol regimes. Scanning electron microscopy (SEM) images showed that leaves grown under aerosol exclusion in filtered air (FA) were lacking the amorphous, flat areas that were abundant on leaves grown in ambient air (AA), suggesting salt crusts formed from deliquescent aerosols. Increasing vapor pressure deficit (VPD) resulted in half the Ball-Berry slope and double WUE for AA compared to FA leaves. This apparent contradiction to the wicking hypothesis may be due to the independent, overcompensating effect of stomatal closure in response to VPD, which affects AA more than FA stomata. Compared to leaves in a more polluted region in the Taiwanese Southwest, NaCl aerosols dominated the leaf surface conditions on mature camphor trees in Eastern Taiwan, while the considerably lower contact angles and the 2.5 times higher minimum epidermal conductances might have come from organic surfactants. Interpretations of SEM images from leaf surface microstructures should consider amorphous areas as possible indicators of aerosol deposition and other hygroscopic material. The amount and type of the material determine the resulting impacts on plant water relations, together with the surrounding atmosphere and ecophysiological traits.

Spatiotemporal Differences and Ecological Risk Assessment of Heavy Metal Pollution of Roadside Plant Leaves in Baoji City, China

The concentration of heavy metals in plants’ leaves can effectively indicate the spatiotemporal differences of environmental pollution, providing a scientific basis for the monitoring of urban air quality. The concentration of Ni, Cu, Cd, Pb and Zn in the leaves of five different species (Ophiopogon japonicus, Ligustrum vicaryi, Platanus acerifolia, Sophora japonicaand Cedrusdeodara) were measured, which were from I, II, III, IV (0.05 m, 0.25 m, 1 m, 4 m) at different times (May and November) in the green belt of Baoji city. The degree of heavy metal pollution and potential ec ological risk were analyzed. The results revealed that the concentration of Zn, Cu and Pb in roadside plant leaves was relatively high. In May, the heavy metal concentration was the highest in the leaves of C.deodara, whereas this was the case for S. japonica in November. Arbors were more effective at capturing particles from the atmosphere than low plants. At the same height, areas with high levels of heavy metal pollution in May were basically the same as that in November, and areas with high levels of pollution were affected by traffic and industry. The pollution index and the comprehensive index of potential ecological risk of element Cd were the highest, indicating that the potential harm of Cd to the environment should receive more attention from the Government.