Accumulation Of Particulate Matter Research Articles

His dark materials: Quantifying the problem of dust (particulate matter) in the agricultural landscape of California

The composition and amounts of dust or particulate matter (PM) vary greatly in the atmosphere and particulates can have major adverse impacts on human health. Since PM10 deposition to foliage can improve air quality, there have been a number of studies of PM10 amounts on the surface of urban vegetation. Much less is known about PM in agricultural areas, although PM10 can be harmful to vegetation and, for food crops, have the potential to be ingested. Here we have quantified PM across the agricultural landscape of California, measuring the amounts present on the foliage of 18 crops at 21 locations. The amounts of particulates present varied (0.17–6.9 gm-2) and PM loads on leaves in the south and east of the area were higher than those in the northern and westerly locations. Our findings suggest that the amounts of particulates on the surface of agricultural crops can be high; exceeding the usual range of values for urban areas. Our data indicate that agricultural crops grown in regions like California and the Mediterranean where summer rainfall is largely absent and drip rather than spray irrigation is used are more vulnerable to PM accumulation and to any adverse effects resulting from these deposits. Microscopic analysis of PM10 on foliage showed that in these agricultural areas wind-blown soil particles make up 74.2% of the PM10 present; this is thus a very significant source. A small number of microplastic particles (2.2%) were also identified on foliage. We suggest that PM and microplastics could impact food and forage quality and that more work is needed to examine PM deposition to crops and their range of impacts.

Analysis of gas flow and PM movement characteristics inside diesel particulate filter channel

Based on experimental data from engine after-treatment tests, the diesel particulate filter (DPF) microscopic channel model was constructed using UG, and the accumulation of particulate matter (PM) in the deep bed filter layer and carbon deposit layer was analyzed through computational fluid dynamics (CFD). A comprehensive study was conducted on the exhaust gas flow characteristics and PM movement within the DPF channel, and focus on the effects of PM distribution type on capture and regeneration characteristics. The results show that with the increase in particle size in the exhaust, the distribution of PM concentration along the axial position of the channel shows a trend of gradually shifting from 0.2 to 0.25 m (rear section) to 0.125–0.2 m (front section). In particular, PM with 1 μm particle size has a large motion inertia, which is easy to move out of the airflow and deposit in the middle part of the channel. For PM in the front and middle sections of the channel, the airflow obstruction is relatively small, but the heat transfer loss is large, which is not beneficial for PM regeneration in the rear section. Therefore, with the distribution of LID, PD-1, and PD-2, the regeneration efficiency is relatively low, at 50.84%, 55.01%, and 54.59%, respectively.

Assessment of seasonal variations in particulate matter accumulation and elemental composition in urban tree species

Outdoor air pollution in urban areas, especially particulate matter (PM), is harmful to human health. Urban trees and shrubs provide crucial ecosystem services such as air pollution mitigation by acting as natural filters. However, urban greenery comprises a particular biodiversity, and different plant species vary in their capacity to accumulate PM. Twenty-two plant species were analyzed and selected according to their leaf traits, the different fractions of PM accumulated on the leaves (large - PML, coarse - PMC, and fine - PMF) and their chemical composition. The study was conducted in four city zones: urban traffic (UT), urban background (UB), industrial (IND), and rural (RUR), comparing winter (W) and summer (S) seasons. The average PM levels in the air and accumulated on the leaves were higher in W than in S season. During both seasons, the highest PM accumulated on the leaves was recorded at the UT zone. Nine species were selected as the most suitable for accumulating PML, seven as the most efficient for accumulating PMC, and six for accumulating PMF. The leaf area and leaf roundness were correlated negatively with PM accumulation. The evergreen species L. nobilis was indicated as suitable for dealing with air pollution based on PM10 and PM2.5 values recorded in the air. Regarding the PM element and metal composition, L. nobilis, Photinia x fraseri, Olea europaea, Quercus ilex and Nerium oleander were selected as species with notable elements and metal accumulation. In summary, the study identified species with higher PM accumulation capacity and assessed the seasonal PM accumulation patterns in different city zones, providing insights into the species interactions with PM and their potential for monitoring and coping with air pollution.

Greenery planning for urban air pollution control based on biomonitoring potential: Explicit emphasis on foliar accumulation of particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs)

In this study, efficiencies of eight indigenous plants of Baishnabghata Patuli Township (BPT), southeast Kolkata, India, were explored as green barrier species and potentials of plant leaves were exploited for biomonitoring of particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs). The present work focused on studying PM capturing abilities (539.32−2766.27 μg cm−2) of plants (T. divaricata, N. oleander and B. acuminata being the most efficient species in retaining PM) along with the estimation of foliar contents of PM adhered to leaf surfaces (total sPM (large + coarse): 526.59−2731.76 μg cm−2) and embedded within waxes (total wPM (large + coarse): 8.73−34.51 μg cm−2). SEM imaging used to analyse leaf surfaces affirmed the presence of innate corrugated microstructures as main drivers for particle capture. Accumulation capacities of PAHs of vehicular origin (total index, TI > 4) were compared among the species based on measured concentrations (159.92−393.01 μg g−1) which indicated T. divaricata, P. alba and N. cadamba as highest PAHs accumulators. Specific leaf area (SLA) of plants (71.01−376.79 cm2 g−1), a measure of canopy−atmosphere interface, had great relevance in PAHs diffusion. Relative contribution (>90%) of 4–6 ring PAHs to total carcinogenic equivalent and potential as well as 5−6 ring PAHs to total mutagenic equivalent and potential had also been viewed with respect to benzo[a]pyrene. In−depth analysis of foliar traits and adoption of plant−based ranking strategies (air pollution tolerance index (APTI) and anticipated performance index (API)) provided a rationale for green belting. Each of the naturally selected plant species showed evidences of adaptations during abiotic stress to maximize survival and filtering effects for reductive elimination of ambient PM and PAHs, allowing holistic management of green spaces.

Can models adequately reflect how long-term nitrogen enrichment alters the forest soil carbon cycle?

Abstract. Changes in the nitrogen (N) status of forest ecosystems can directly and indirectly influence their carbon (C) sequestration potential by altering soil organic matter (SOM) decomposition, soil enzyme activity, and plant–soil interactions. However, model representations of linked C–N cycles and SOM decay are not well validated against experimental data. Here, we use extensive data from the Fernow Experimental Forest long-term whole-watershed N fertilization study to compare the response to N perturbations of two soil models that represent decomposition dynamics differently (first-order decay versus microbially explicit reverse Michaelis–Menten kinetics). These two soil models were coupled to a common vegetation model which provided identical input data. Key responses to N additions measured at the study site included a shift in plant allocation to favor woody biomass over belowground carbon inputs, reductions in soil respiration, accumulation of particulate organic matter (POM), and an increase in soil C:N ratios. The vegetation model did not capture the often-observed shift in plant C allocation with N additions, which resulted in poor predictions of the soil responses. We modified the parameterization of the plant C allocation scheme to favor wood production over fine-root production with N additions, which significantly improved the vegetation and soil respiration responses. Additionally, to elicit an increase in the soil C stocks and C:N ratios with N additions, as observed, we modified the decay rates of the POM in the soil models. With these modifications, both models captured negative soil respiration and positive soil C stock responses in line with observations, but only the microbially explicit model captured an increase in soil C:N. Our results highlight the need for further model development to accurately represent plant–soil interactions, such as rhizosphere priming, and their responses to environmental change.

Façade Greening for Healthy Urban Air: An Umbrella Review on Particulate Matter Reduction, Challenges, and Future Directions

Particulate matter (PM) exposure in urban areas is a continuous threat to human health and requires sustainable solutions for effective reduction. The aim of this study is to provide a comprehensive overview of façade greening and its effects on PM and to identify knowledge gaps. We systematically screened, analyzed, and re-evaluated previous reviews according to the criteria established for an umbrella review. As a result, this study covers and discusses common measurement methods, influencing factors, the effectiveness of façade greening, leaf characteristics, and plant species from different subtopics. The main findings are that inconsistent measurement methods limit the comparability of the analyzed reviews, and different climatic conditions affecting the use of plant species lead to different international effects. Despite the existing studies reporting a positive effect on the reduction of PM, comparability is difficult due to methodological differences and external influences. Given the complexity, interdisciplinary collaboration with experts is essential to increase the effectiveness of façade greening for PM accumulation for healthy urban air. We suggest that this umbrella review provides a foundation for future research and practical implementations, such as a suitable plant selection or façade design, by integrating the results.

Examination of Air Quality of Dr. Sami Yağız Street in Niğde

Air pollution can be defined as the accumulation of gas, air, or particulate matter released as a result of fuel residues and chemical processes in the atmosphere in amounts that harm the lives of living things. Rapid urbanization, industrialization, increase in the number of motor vehicles, meteorological conditions, fuels used for heating, and the spread of industrial establishments and thermal power plants play an important role in the increase in air pollution. Air pollution is a major environmental problem affecting people in both developed and developing countries, and it is estimated that megacities in developing countries, and a quarter of the world's population are exposed to unhealthy concentrations of air pollutants. People living in cities with high outdoor air pollution are more likely to suffer from heart disease, respiratory problems, and lung cancer than those living in urban areas with clean air. In the industrialized western world, urban air pollution is in some respects in its final stages, with a dramatic decline in SO2 and soot levels. The increase in the number of private vehicles is a newly emerging problem. Rapid urbanization in most developing countries has so far led to uncontrolled growth and environmental degradation. Air pollution levels are still rising in many cities. In this study, air quality was tried to be measured along Dr. Sami Yağız Street, which is one of the most heavily used areas of Niğde. H2S, O2 and CO measurements were made at 25 points at equal intervals on both sides of the street. Measurements were made at a total of 4 different time periods per day. The obtained values were transferred to ArcGIS 10.3 software and maps were produced. Measurement of gases other than H2S is not distributed homogeneously along the street, and traffic density and the businesses on the sides of the street cause changes in the rates of the gases.

Climate and mineral accretion as drivers of mineral‐associated and particulate organic matter accumulation in tidal wetland soils

AbstractTidal wetlands sequester vast amounts of organic carbon (OC) and enhance soil accretion. The conservation and restoration of these ecosystems is becoming increasingly geared toward “blue” carbon sequestration while obtaining additional benefits, such as buffering sea‐level rise and enhancing biodiversity. However, the assessments of blue carbon sequestration focus primarily on bulk SOC inventories and often neglect OC fractions and their drivers; this limits our understanding of the mechanisms controlling OC storage and opportunities to enhance blue carbon sinks. Here, we determined mineral‐associated and particulate organic matter (MAOM and POM, respectively) in 99 surface soils and 40 soil cores collected from Chinese mangrove and saltmarsh habitats across a broad range of climates and accretion rates and showed how previously unrecognized mechanisms of climate and mineral accretion regulated MAOM and POM accumulation in tidal wetlands. MAOM concentrations (8.0 ± 5.7 g C kg−1) (±standard deviation) were significantly higher than POM concentrations (4.2 ± 5.7 g C kg−1) across the different soil depths and habitats. MAOM contributed over 51.6 ± 24.9% and 78.9 ± 19.0% to OC in mangrove and saltmarsh soils, respectively; both exhibited lower autochthonous contributions but higher contributions from terrestrial or marine sources than POM, which was derived primarily from autochthonous sources. Increased input of plant‐derived organic matter along the increased temperature and precipitation gradients significantly enriched the POM concentrations. In contrast, the MAOM concentrations depended on climate, which controlled the mineral reactivity and mineral–OC interactions, and on regional sedimentary processes that could redistribute the reactive minerals. Mineral accretion diluted the POM concentrations and potentially enhanced the MAOM concentrations depending on mineral composition and whether the mineral accretion benefited plant productivity. Therefore, management strategies should comprehensively consider regional climate while regulating sediment supply and mineral abundance with engineering solutions to tap the OC sink potential of tidal wetlands.

Is hydrophobic coating on glass equally efficient in reducing % soiling loss of solar PVs in clean and polluted environments?

Hydrophobic-coated glass (CS) on PV surfaces is known to reduce particulate matter (PM) accumulation. However, there is no comparative study on the % reduction in soiling loss (% RSL) on CS with respect to uncoated glass (UCS) for clean and polluted environments (higher atmospheric PM). The present field study (∼210 km2 in Gujarat, Western India) focuses on the evaluation of particle-size distribution of PM on CS and UCS, quantification of size-resolved soiling due to PM accumulation on CS and UCS, and comparison of % RSL of CS in cleaner and polluted environments. The findings show that 3 to 10 µm particles contribute to ∼21 % and ∼12 % of the total mass accumulated on CS and UCS, respectively. The observations are also validated using the theoretical adhesion model and critical rebounding velocity. Moreover, this particle-size fraction contributes to ∼50 % of the total soiling loss for CS against only ∼27 % soiling loss for UCS. Therefore, CS surfaces under polluted environments are expected to have a higher % of finer particle-size fraction in accumulated PM, which contributes significantly to the total soiling loss of CS and reduces the difference in % soiling loss between CS and UCS. Although CS reduces PM accumulation in both clean and polluted regions, the % RSL using CS is comparatively less in a polluted environment. The observations from the present study provide greater insight into the soiling aspect of solar PVs and have significant economic implications in deploying PV surfaces with hydrophobic coated glass.

The influence of plant species, leaf morphology, height and season on PM capture efficiency in living wall systems

Green infrastructure (GI) is already known to be a suitable way to enhance air quality in urban environments. Living wall systems (LWS) can be implemented in locations where other forms of GI, such as trees or hedges, are not suitable. However, much debate remains about the variables that influence their particulate matter (PM) accumulation efficiency. This study attempts to clarify which plant species are relatively the most efficient in capturing PM and which traits are decisive when it comes to the implementation of a LWS. We investigated 11 plant species commonly used on living walls, located close to train tracks and roads. PM accumulation on leaves was quantified by magnetic analysis (Saturation Isothermal Remanent Magnetization (SIRM)). Several leaf morphological variables that could potentially influence PM capture were assessed, as well as the Wall Leaf Area Index. A wide range in SIRM values (2.74–417 μA) was found between all species. Differences in SIRM could be attributed to one of the morphological parameters, namely SLA (specific leaf area). This suggest that by just assessing SLA, one can estimate the PM capture efficiency of a plant species, which is extremely interesting for urban greeners. Regarding temporal variation, some species accumulated PM over the growing season, while others actually decreased in PM levels. This decrease can be attributed to rapid leaf expansion and variations in meteorology. Correct assessment of leaf age is important here; we suggest individual labeling of leaves for further studies. Highest SIRM values were found close to ground level. This suggests that, when traffic is the main pollution source, it is most effective when LWS are applied at ground level. We conclude that LWS can act as local sinks for PM, provided that species are selected correctly and systems are applied according to the state of the art.

Nanopatterned Electroactive Polylactic Acid Nanofibrous MOFilters for Efficient PM0.3 Filtration and Bacterial Inhibition.

Biodegradable polylactic acid (PLA) nanofibrous membranes (NFMs) hold great potential to address the increasing airborne particulate matter (PM) and dramatic accumulation of plastic/microplastic pollution. However, the field of PLA NFM-based filters is still in its infancy, frequently dwarfed by the bottlenecks regarding relatively low surface activity, poor electroactivity, and insufficient PM capturing mechanisms. This effort discloses a microwave-assisted approach to minute-level synthesis of dielectric ZIF-8 nanocrystals with high specific surface area (over 1012 m2/g) and ultrasmall size (∼240 nm), which were intimately anchored onto PLA nanofibers (PLA@ZIF-8) by a combined "electrospinning-electrospray" strategy. This endowed the PLA@ZIF-8 NFMs with largely increased electroactivity in terms of elevated dielectric coefficient (an increase of 202%), surface potential (up to 5.8 kV), and triboelectric properties (output voltage of 30.8 V at 10 N, 0.5 Hz). Given the profound control over morphology and electroactivity, the PLA@ZIF-8 NFMs exhibited efficient filtration of PM0.3 (97.1%, 85 L/min) with a decreased air resistance (592.5 Pa), surpassing that of the pure PLA counterpart (88.4%, 650.9 Pa). This was essentially ascribed to realization of multiple filtration mechanisms for PLA@ZIF-8 NFMs, including enhanced physical interception, polar interactions, and electrostatic adsorption, and the unique self-charging function triggered by airflow vibrations. Moreover, perfect antibacterial performance was achieved for PLA@ZIF-8, showing ultrahigh inhibition rates of 99.9 and 100% against E. coli and S. aureus, respectively. The proposed hierarchical structuring strategy, offering the multifunction integration unattainable with conventional methods, may facilitate the development of biodegradable long-term air filters.

Unraveling the link: exploring the effects of environmental change on the cardiovascular system.

Climate change has a particularly detrimental effect on the cardiovascular system, which is highly vulnerable to harmful impacts. The accumulation of particulate matter (PM) and greenhouse gasses in the environment negatively impacts the cardiovascular system through several mechanisms. The burden of climate change-related diseases falls disproportionately on vulnerable populations, including the elderly, the poor, and those with pre-existing health conditions. A key component of addressing the complex interplay between climate change and cardiovascular diseases is acknowledging health disparities among vulnerable populations resulting from climate change, familiarizing themselves with strategies for adapting to changing conditions, educating patients about climate-related cardiovascular risks, and advocating for policies that promote cleaner environments and sustainable practices.

The health and economic impacts of emergency measures to combat heavy air pollution

Emergency measures are effective measures that can be quickly taken in response to heavy air pollution. They not only have an obvious impact on slowing down the accumulation of particulate matter but also have a significant impact on public health and socio-economic development. Therefore, to analyze the effectiveness of emergency measures, one must assess their environmental, health and economic impacts. In this paper, we use exposure-response functions and a city-level computable general equilibrium (CGE) model to do so for China's Jing-Jin-Ji region. We find that the emergency measures implemented in 2019 significantly improve the region's air quality and enhance public health by reducing risk associated with acute bronchitis. Moreover, those emergency measures notably benefit the Jing-Jin-Ji region economically by expanding labor supply, most notably in Beijing and Tianjin. It seems Beijing and Tianjin should compensate industrial cities in Hebei, which enabled the Jing-Jin-Ji region's better air quality but encountered far fewer economic benefits. Handan, Baoding, and Cangzhou are among the cities in Hebei that are expanding employment in manufacturing and service sectors. These results can provide scientific guidance and policy suggestions for government while using emergency measures to combat regional heavy air pollution considering its health and economic benefits.

A Review on Seasonal Changes in Particulate Matter Accumulation by Plant Bioindicators: Effects on Leaf Traits

A Review on Seasonal Changes in Particulate Matter Accumulation by Plant Bioindicators: Effects on Leaf Traits

Depth-dependent effects of ericoid mycorrhizal shrubs on soil carbon and nitrogen pools are accentuated under arbuscular mycorrhizal trees.

Plant mycorrhizal associations influence the accumulation and persistence of soil organic matter and could therefore shape ecosystem biogeochemical responses to global changes that are altering forest composition. For instance, arbuscular mycorrhizal (AM) tree dominance is increasing in temperate forests, and ericoid mycorrhizal (ErM) shrubs can respond positively to canopy disturbances. Yet how shifts in the co-occurrence of trees and shrubs with different mycorrhizal associations will affect soil organic matter pools remains largely unknown. We examine the effects of ErM shrubs on soil carbon and nitrogen stocks and indicators of microbial activity at different depths across gradients of AM versus ectomycorrhizal (EcM) tree dominance in three temperate forest sites. We find that ErM shrubs strongly modulate tree mycorrhizal dominance effects. In surface soils, ErM shrubs increase particulate organic matter accumulation and weaken the positive relationship between soil organic matter stocks and indicators of microbial activity. These effects are strongest under AM trees that lack fungal symbionts that can degrade organic matter. In subsurface soil organic matter pools, by contrast, tree mycorrhizal dominance effects are stronger than those of ErM shrubs. Ectomycorrhizal tree dominance has a negative influence on particulate and mineral-associated soil organic matter pools, and these effects are stronger for nitrogen than for carbon stocks. Our findings suggest that increasing co-occurrence of ErM shrubs and AM trees will enhance particulate organic matter accumulation in surface soils by suppressing microbial activity while having little influence on mineral-associated organic matter in subsurface soils. Our study highlights the importance of considering interactions between co-occurring plant mycorrhizal types, as well as their depth-dependent effects, for projecting changes in soil carbon and nitrogen stocks in response to compositional shifts in temperate forests driven by disturbances and global change.

Short-term particulate matter contamination severely compromises insect antennal olfactory perception

The consequences of sub-lethal levels of ambient air pollution are underestimated for insects, for example, the accumulation of particulate matter on sensory receptors located on their antennae may have detrimental effects to their function. Here we show that the density of particulate matter on the antennae of houseflies (Musca domestica) collected from an urban environment increases with the severity of air pollution. A combination of behavioural assays, electroantennograms and transcriptomic analysis provide consistent evidence that a brief exposure to particulate matter pollution compromises olfactory perception of reproductive and food odours in both male and female houseflies. Since particulate matter can be transported thousands of kilometres from its origin, these effects may represent an additional factor responsible for global declines in insect numbers, even in pristine and remote areas.

Species-specific influence of powdery mildew mycelium on the efficiency of PM accumulation by urban greenery.

Particulate matter (PM) is one of the most important air pollutants, especially in urban areas. The efficiency of PM biofiltration by plants depends on the morphological features of the foliage. More PM is deposited on complex leaves, covered with thick wax layer, trichomes, epidermal glands, and convex venation. Very few literature reports suggest that also the presence of mycelium of nonparasitic and saprophytic fungi positively affects the accumulation of PM on the leaves. In this work, to our best knowledge, for the first time the effect of the mycelium of the parasitic powdery mildew on the efficiency of PM accumulation by urban greenery was studied. Uninfested and fungus-infested leaves of Acer negundo L., Malus domestica Borkh Quercus robur L., and Berberis vulgaris L. were harvested in July in the center of Warsaw city. The effect of powdery mildew infection on PM accumulation was species-specific. A higher amount of PM on leaves not infected with powdery mildew was found in M. domestica and Q. robur, while in A. negundo and B. vulgaris more PM was accumulated on leaves infected with fungus. All species (except A. negundo) accumulated more of the PM of 0.2-2.5-μm and 2.5-10-μm size fractions on leaves not infected with powdery mildew. One of the greatest consequences of the presence of powdery mildew mycelium on the foliage is most probably reduction of the direct involvement of waxes in PM accumulation and retention processes.

Impact of different ventilation conditions on tobacco smoke-associated particulate matter emissions in a car cabin using the TAPaC platform

Despite antagonizing attempts from the tobacco industry, passive inhalation of tobacco smoke is known to be cancerogenic and toxic to human health for decades. Nonetheless, millions of non-smoking adults and children are still victims of second-hand smoke. Accumulation of particulate matter (PM) in confined spaces such as the car are particularly harmful due to high concentrations. We here aimed to analyze the specific effects of ventilation conditions in the setting of a car. By the use of the measuring platform TAPaC (tobacco-associated particulate matter emissions inside a car cabin), 3R4F reference cigarettes, Marlboro red, and Marlboro gold were smoked in a car interior with a volume of 3.709 m3. Seven different ventilation conditions (C1–C7) were analyzed. Under C1, all windows were closed. Under C2–C7, the car ventilation was turned on power level 2/4 with the air directed towards the windshield. Only the passenger side window was opened, where an outer placed fan could create an airstream speed of 15.9–17.4 km/h at one meter distance to simulate a driving car. C2: Window 10 cm opened. C3: Window 10 cm opened with the fan turned on. C4: Window half-opened. C5: Window half-opened with the fan turned on. C6: Window fully opened. C7: Window fully opened with the fan turned on. Cigarettes were remotely smoked by an automatic environmental tobacco smoke emitter and a cigarette smoking device. Depending on the ventilation condition the cigarettes emitted different mean PM concentrations after 10 min under condition C1 (PM10: 1272–1697 µg/m3, PM2.5: 1253–1659 µg/m3, PM1: 964–1263 µg/m3) under C2, C4, and C6 (PM10: 68.7–196.2 µg/m3, PM2.5: 68.2–194.7 µg/m3, PM1: 66.1–183.8 µg/m3) C3, C5, and C7 (PM10: 73.7–139 µg/m3, PM2.5: 72–137.9 µg/m3, PM1:68.9–131.9 µg/m3). Vehicle ventilation is insufficient to protect passengers from toxic second-hand smoke completely. Brand-specific variations of tobacco ingredients and mixtures markedly influence PM emissions under ventilation conditions. The most efficient ventilation mode to reduce PM exposure was achieved by opening the passenger´s window 10 cm and turning the onboard ventilation on power level 2/4. In-vehicle smoking should be banned to preserve innocent risk groups (e.g., children) from harm.

The expansion of evergreen and deciduous shrubs changed the chemical characteristics and biological community of alpine meadows soil

Global warming drives shrubs expansion. However, it is unclear how shrubs expansion affect the nutrients cycling, decomposer diversity and activity of alpine meadows. We selected two dominant shrub species in an alpine forest-Tundra ecotone on the eastern Tibetan Plateau: Rhododendron lapponicum (evergreen shrubs), and Sorbus rufopilosa (deciduous shrubs), the shrub-free tundra site as the control site. The fauna community diversity, microbial biomass, extracellular enzyme activity and enzyme stoichiometry of organic soil and mineral soil layer were determined to explore the effects of shrubs expansion. The soil total nitrogen, microbial biomass carbon and nitrogen, and some extracellular enzyme activity of the two shrubs were higher than those in CK. In addition, deciduous shrub expansion had a stronger effect on meadows ecosystem process than evergreen shrub expansion. However, both of them may alleviate the limitation of nitrogen and phosphorus in alpine meadows ecosystem, and the expansion of evergreen shrubs may also contribute to the accumulation of particulate organic matter. It is of great significance to probe the biogeochemical cycle of alpine meadows ecosystems under climate change.

Particulate Matter Accumulation and Elemental Composition of Eight Roadside Plant Species

Particulate matter (PM) is the most dangerous air pollutant that adversely affects health. Increasing PM in urban areas is a big problem that must be solved. This study analyzed the amount of PM that accumulated on plant leaves, as well as the leaf traits that contribute to PM accumulation, to determine the plant’s ability to accumulate PM and the impact of PM on the plants. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to quantitatively assess metal concentrations in the particles that had accumulated on the leaf samples. Eight common plant species that grow on the roadside were used to analyze leaf traits using leaf samples. Specific leaf areas (SLA), leaf extract pH (pH), relative leaf water content (RWC), chlorophyll (Chl), and carotenoids were analyzed. PM accumulation and leaf traits varied among plant species, and Parthenocissus tricuspidata showed the highest PM accumulation on its leaf surface. The leaf’s elemental composition included C, O, Ca, K, Mg, S, P, Al, Si, Na, Cl, and Fe. Among these elements, Ca, K, and Cl made up a relatively large percentage. Fe was only detected in the leaves of Pachysandra terminalis and P. tricuspidata, while C and O were excluded as they are not relevant in determining PM metal content. Plants not only accumulate PM but also heavy metals from the atmosphere. This study found that plants with highly effective PM accumulation, such as P. tricuspidate, should be considered for optimizing the benefits of plants in improving air quality.