Accumulation Of Pollutants Research Articles

Riparian Soil Pollution Caused by Sediment Metal Transport: Seasonal Changes and Ecological Risk Assessment.

The accumulation of pollutants in the sediment along surface water may negatively affect riparian zones and increase ecological risk. This article investigates the effects of metal sediments on riparian soil via field monitoring and ICP-OES analysis. To this end, pollution levels, seasonal changes, and potential sources of the pollutants were determined for the Melen River watershed, Turkey. The ecological statuses (contamination factor, enrichment factor, index of geo-accumulation, pollution index, modified pollution index, and potential and modified ecological risk indexes) of the watershed were also analyzed. Although no significant seasonal differences in the metal sediments were observed, their spatial distribution in the sediments and riparian soils varied markedly. Cr (11.4 to 136), Co (7.7 to 21.52), Cu (11.4 to 76.6), and Ni (14.06 to 128.2) recorded as mg/kg significantly increased from the upstream to the downstream. The metals possessing the highest risk in the sediment and riparian soil regarding the river health were Cu, Co, and Ni. The risk values were found to be heavily polluted (PI > 3 and MPI > 10), and the risk indexes were above the "desired environment without the risk". The risk index was found to be more than 50, and the modified risk indexes exceeded 200 at many points. The transportation of pollutants in surface water became evident in the sediment, resulting in adverse effects on the riparian zone and the ecological system.

SiO2/WO3/ZnO based self-cleaning coatings for solar cells

The accumulation of pollution and any kinds of contamination on the glass cover of the solar cell affects the efficiency of the photovoltaic (PV) systems. The contamination on the glass cover can absorb and reflect a certain part of the sunlight irradiation, which can decrease the intensity of the light coming in through the glass cover. With the study, it was planned to develop self-cleaning coatings for the PV systems. It was aimed to prevent or reduce the contamination-induced efficiency loss of the existing PV systems. In the scope of the project, SiO2/WO3 and SiO2/WO3/ZnO composites were coated from their solutions on the glass substrates using a dip-coating technique. WO3 was selected as a photocatalyst semiconductor. Under the UV light irradiation, WO3 could absorb the photons of the UV light, generating the photoinduced charge carriers. The photoexcited charge carriers provide both the photoinduced hydrophilicity on the surface of the coating and the photocatalytic degradation of the organic contaminants accumulated on the surface of the coating, which allows water droplets to spread and flow on the surface of the cover glass to remove the contaminations. However, the recombination rate of the photoexcited charge carriers on the WO3 film was high. In order to suppress the recombination of the photoinduced charge carriers, WO3 was coupled with SiO2 and ZnO. Both of these semiconductors improved the photocatalytic activity of the WO3 film. Although SiO2 has superior features in terms of the light transmission, it was not very effective under UV light as a photocatalyst alone. The widely preferred photocatalyst ZnO was added into the composite film structure to enhance the photocatalytic activity. The self-cleaning mechanism of the film coatings on a solar cell was investigated through the photocatalytic dye removal efficiency on the as-prepared film samples. There was a slight decrease in the light transparency and the solar cell efficiency because of the WO3 content of the composite film. On the other hand, coupling the SiO2/WO3 film with ZnO enhanced the photocatalytic activity, and it suppressed the reduction effect of the WO3 phase on both the light transparency and the solar cell efficiency. The photocatalytic dye removal efficiency was increased to over 90% after 240 min of UVA light irradiation. In addition, the solar cell coated with the SiO2/WO3/ZnO film provided almost the same solar cell efficiency as the uncoated solar cell. The water contact angle measurement also exhibited the photocatalytic degradation of the model contamination on the glass cover of the solar cell under the UVA light irradiation.Graphical

Spatial distribution characteristics and degradation mechanism of microorganisms in n-hexadecane contaminated vadose zone

The damage caused by petroleum hydrocarbon pollution to soil and groundwater environment is becoming increasingly significant. The vadose zone is the only way for petroleum hydrocarbon pollutants to leak from surface into groundwater. The spatial distribution characteristics of indigenous microorganisms in vadose zone, considering presence of capillary zones, have rarely been reported. To explore the spatial distribution characteristics of indigenous microorganisms in vadose zone contaminated by petroleum hydrocarbons, a one-dimensional column migration experiment was conducted using n-hexadecane as characteristic pollutant. Soil samples were collected periodically from different heights during experiment. Corresponding environmental factors were monitored online. The microbial community structure and spatial distribution characteristics of the cumulative relative abundance were systematically analyzed using 16S rRNA sequencing. In addition, the microbial degradation mechanism of n-hexadecane was analyzed using metabolomics. The results showed that presence of capillary zone had a strong retarding effect on n-hexadecane infiltration. Leaked pollutants were mainly concentrated in areas with strong capillary action. Infiltration and displacement of NAPL-phase pollutants were major driving force for change in moisture content (θ) and electric conductivity (EC) in vadose zone. The degradation by microorganisms results in a downward trend in potential of hydrogen (pH) and oxidation-reduction potential (ORP). Five petroleum hydrocarbon-degrading bacterial phyla and 11 degradable straight-chain alkane bacterial genera were detected. Microbial degradation was strong in the area near edge of capillary zone and locations of pollutant accumulation. Mainly Sphingomonas and Nocardioides bacteria were involved in microbial degradation of n-hexadecane. Single-end oxidation involved microbial degradation of n-hexadecane (C16H34). The oxygen consumed, hexadecanoic acid (C16H32O2) produced during this process, and release of hydrogen ions (H+) were the driving factors for reduction of ORP and pH. The vadose zone in this study considered presence of capillary zone, which was more in line with actual contaminated site conditions compared with previous studies. This study systematically elucidated vertical distribution characteristics of petroleum hydrocarbon pollutants and spatiotemporal variation characteristics of indigenous microorganisms in vadose zone considered presence of capillary zone. In addition, the n-hexadecane degradation mechanism was elucidated using metabolomics. This study provides theoretical support for development of natural attenuation remediation measures for petroleum-hydrocarbon-contaminated soil and groundwater.

Assessment of metal and organic pollutants in combination with stable isotope analysis in tunas from the Gulf of Cadiz (east Atlantic)

Bioaccumulation patterns of heavy metals (Pb, Cd, Cr, Ni, Fe and Cu) and organic (priority and emerging) pollutants, in combination with stable isotope analysis (SIA), were assessed in muscle and liver of three tuna species from the Gulf of Cadiz (Atlantic bluefin tuna, Thunnus thynnus; Atlantic bonito, Sarda sarda, and skipjack tuna, Katsuwonus pelamis). SIA and contaminant (heavy metal and organic) profiles separately discriminated between species. There was no significant overlap between the trophic niches estimated from isotopic data, suggesting that there are diet differences which may determine differential bioaccumulation patterns. The levels of heavy metals and persistent organic pollutants in muscle of all the individuals analyzed were below the allowable limits established by the current legislation. Concentrations of most contaminants were higher in liver than in muscle, underlining the powerful detoxifying capacity of the liver in tunas. In addition to diet, other factors such as size and age (exposure time to environmental chemicals) explain differences in pollutant accumulation patterns in tissues between species, each with varying degrees of involvement depending on the pollutant class. Our results show that combining contaminant profile data with trophic features based on SIA may help understand pollutant bioaccumulation patterns in upper levels of marine food webs.

Causes of an extremely low visibility event in Northeast China

AbstractAn extreme haze‐fog event occurred during October 20–22, 2013, in Harbin, Northeast China, which lasted for nearly 60 h with local visibility as low as 20 m. However, causes of the extreme haze‐fog formation remain unclear. Through the analysis of in situ data and objective weather circulation classification, it is revealed that high pollutant emissions from biomass burning played a very important role in the extreme event. Stable weather conditions under the circulation type 8 (CT8), marked by weak high‐pressure control, strong inversion (6.55°C), shallow boundary layer depth (<300 m), and high relative humidity (>90%), aided in the accumulation of pollutants and hygroscopic aerosol growth. All of these factors collectively contributed to the extreme haze‐fog formation. The insights derived from this study can improve the predictability of extreme haze‐fog events, and indicate that pollution emissions should be tightly controlled in the adverse meteorological circulation type in Northeast China.

Dynamics of pollutants accumulation in the snow of an urban agglomeration

Snowpack properties allow using snow as a convenient indicator of atmospheric air pollution, precipitation, and eventually soil pollution. There is a high probability of trace elements and organic pollutants accumulation on the snow cover acting as the deposit matrix. In this study, we analyzed the dynamics of the content of metals (Ca, Mn, Fe, Zn, Sr, Pb and Ba) in filtered and unfiltered samples and the content of polyaromatic hydrocarbons (18 basic PAHs) in weekly snow sampling in the city and nearby. The obtained results were collated with the content of the same contaminants in the snow sampled layer by layer at the end of the season (layer thickness was 0.1 m). In result of the study, we concluded that the sampling should be carried out right after the precipitation for the purpose of atmospheric pollution estimation, because most of heavy metals migrate through the snow layers into soil cover and get lost by the end of the season. The organic pollutants, such as PAHs, are also lost. The sampling of snow during the whole season allows identifying the global and local sources of contaminants released into the atmosphere.

CFD-DPM Simulation on the Atmospheric Pollutant Dispersion in Industrial Park

In order to mitigate the impact of particulate pollutants in Nanjing Sample Industrial Park, it is imperative to simulate the wind field and pollutant dispersion inside the park. Therefore, a CFD-DPM study was employed to simulate the wind field and pollutant dispersion with an accurate landform model. A large eddy simulation was utilized for calculating wind flow distribution inside the park, which is more suitable than Reynolds-Averaged Navier–Stokes Equations (RANS). The physical model of the plant canopy was incorporated to assess its influence on the wind field and particulate pollutants through drag, buoyancy, and deposition effects. Using this method, the distributions of the wind field, and contaminant and the sensitivity tests were obtained by means of calculating a number of research cases under different meteorological conditions. In the numerical results, the wind field was obstructed by the plant canopy, resulting in near-ground uniformity under unstable weather conditions. The distribution of particulate pollutants was influenced not only by the drag and buoyancy effects but also by deposition, which caused an accumulation of particulate pollutants on the windward side of the canopy under unstable weather conditions. The sensitivity tests were performed by comparing the concentrations of particulate pollutants under various conditional settings. The canopy regions can remove the particulate pollutant by 50% under stable weather conditions. The deposition effect is enhanced by larger particle density and diameter and is also influenced by leaf area density.

A comprehensive review of water quality control on lentic ecosystem through the water quality, IoT and aeration models

Eutrophication is the term used to describe the phenomenon in which a body of water becomes excessively loaded with nutrients, leading to a population of basic plant life. Excessive growth of algae and planktonic organism’s manifests as blooms on the water surface. Eutrophication gets worse in a lentic ecosystem when there is no outflow or water movement, resulting in the accumulation of pollutants on the surface. Water quality measurements, including temperature, pH, dissolved oxygen (DO), and biochemical oxygen demand (BOD), exhibit correlations with one another. Therefore, this article provides a comprehensive review of the water quality model, aeration system, and IoT technology. The water quality model enables the development of forecasts on future water quality. Therefore, effective water quality management can be strategized based on the specific attributes of the water. In addition, an aeration system is a technology used to improve water quality by enhancing oxygen levels and decreasing nutrient levels. Furthermore, it has been shown that real-time surveillance with IoT technology can enhance precision, effectiveness, and reduce time consumption. Therefore, it is important to priorities the implementation of water quality model, aeration, and IoT technology since they offer significant benefits in controlling water quality.

Application of Machine Learning to Estimate Ammonia Atmospheric Emissions and Concentrations

This paper describes an innovative method that recursively applies the machine learning Random Forest to an assumed homogeneous aerographic domain around measurement sites to predict concentrations and emissions of ammonia, an atmospheric pollutant that causes acidification and eutrophication of soil and water and contributes to secondary PM2.5. The methodology was implemented to understand the effects of weather and emission changes on atmospheric ammonia concentrations. The model was trained and tested by hourly measurements of ammonia concentrations and atmospheric turbulence parameters, starting from a constant emission scenario. The initial values of emissions were calculated based on a bottom-up emission inventory detailed at the municipal level and considering a circular area of about 4 km radius centered on measurement sites. By comparing predicted and measured concentrations for each iteration, the emissions were modified, the model’s training and testing were repeated, and the model converged to a very high performance in predicting ammonia concentrations and establishing hourly time-varying emission profiles. The ammonia concentration predictions were extremely accurate and reliable compared to the measured values. The relationship between NH3 concentrations and the calculated emissions rates is compatible with physical atmospheric turbulence parameters. The site-specific emissions profiles, estimated by the proposed methodology, clearly show a nonlinear relation with measured concentrations and allow the identification of the effect of atmospheric turbulence on pollutant accumulation. The proposed methodology is suitable for validating and confirming emission time series and defining highly accurate emission profiles for the improvement of the performances of chemical and transport models (CTMs) in combination with in situ measurements and/or optical depth from satellite observation.

Vertical variation of source-apportioned PM2.5 and selected volatile organic compounds near an elevated expressway in an urban area.

Fine particulate matter (PM2.5) and volatile organic compounds (VOCs) are associated with adverse health effects and show spatial variation in three dimensions. The present study attempted to evaluate source contributions of PM2.5 and toxic VOCs in a metropolitan area focusing on the associated vertical variations. A special emphasis is put on the effects of the elevated expressway on the vertical variability of contribution estimates of the identified sources. Nine source factors, i.e., soil dust, sea salt/oil combustion, secondary nitrate, industrial emission, aged VOCs/secondary aerosol, traffic-related I, solvent use/industrial process, secondary sulfate, and traffic-related II, were identified using positive matrix factorization (PMF). The main contributors to PM2.5 were secondary sulfate (19.1%) and traffic-related emissions (traffic-related I and II, 16.1%), whereas the largest contributors to VOCs were traffic-related emissions (37.6%). The influence of the elevated expressway is suggested to be particularly critical on vertical variations of traffic-related emissions, including aging and secondary formation of locally accumulated air pollutants near roads. Increasing the building porosity under the viaduct could reduce the accumulation of air pollutants caused by the shelter effect. Additionally, in-street barriers would be beneficial in reducing population exposure to traffic-related emissions by altering the airflows near roads.

Study on the Vertical Distribution and Transport of Aerosols in the Joint Observation of Satellite and Ground-Based LiDAR

The mechanism of aerosol pollution transport remains highly elusive owing to the myriad of influential factors. In this study, ground station data, satellite data, ground-based LiDAR remote sensing data, sounding data, ERA5 reanalysis and a backward trajectory model were combined to investigate the formation process and optical properties of winter aerosol pollution in Beijing and surrounding areas. The analysis of ground station data shows that compared to 2019 and 2021, the pandemic lockdown policy resulted in a decrease in the total number of pollution days and a decrease in the average concentration of particulate matter in the Beijing area in 2020. The terrain characteristics of the Beijing-Tianjin-Hebei (BTH) made it prone to northeast and southwest winds. The highest incidence of aerosol pollution in Beijing occurs in February and March during the spring and winter seasons. Analysis of a typical heavy aerosol pollution process in the Beijing area from 28 February to 5 March 2019 shows that dust and fine particulate matter contributed to the primary pollution; surface air temperature inversion and an average wind speed of less than 3 m/s were conducive to the continuous accumulation of pollutants, which was accompanied by the oxidation reaction of NO2 and O3, forming photochemical pollution. The heavy aerosol pollution was transmitted and diffused towards the southeast, gradually eliminating the pollution. Our results provide relevant research support for the prevention and control of aerosol pollution.

Evaluation of synthetic sponge to control wave-induced currents in coastal waters

Based on National Oceanic and Atmospheric Administration (NOAA) Coral Reef Conservation Program, climate change causes coral bleaching. In response to the high roughness of coral colonies and reduced current velocity, coral reefs in near-shore regions are susceptible to accumulation of pollutants or sediments. This threatens coral reef ecosystems and causes several challenges. Controlling the wave velocity, Turbulent Kinetic Energy (TKE), and vortical structures help enhance advection/diffusion of particles from coral reef zones.In the current study, a device inspired by a marine sponge (synthetic sponge), was designed. A suction/pumping function was devised through two concentric perforated cylinders to simulate this mechanism in the synthetic sponge. Several physical and numerical experiments (using OpenFOAM software considering RANS modeling) were carried out to investigate the effects of geometrical characteristics (i.e., cylinder and perforation diameters) of synthetic sponge on wave hydrodynamics. Accordingly, wave attenuation, mean horizontal and orbital velocities, turbulent kinetic energy, and vortex structures were evaluated. In summary, the results indicated that the pumping flow can act as an energy recovery downstream of the sponge, and the horizontal velocity and TKE growing in the water column due to generation of special vortices. Therefore, the current synthetic sponge can improve momentum transfer.

Chemical and microbiological insights into two littoral Antarctic demosponge species: Haliclona (Rhizoniera) dancoi (Topsent 1901) and Haliclona (Rhizoniera) scotti (Kirkpatrick 1907).

Antarctic Porifera have gained increasing interest as hosts of diversified associated microbial communities that could provide interesting insights on the holobiome system and its relation with environmental parameters. The Antarctic demosponge species Haliclona dancoi and Haliclona scotti were targeted for the determination of persistent organic pollutant (i. e., polychlorobiphenyls, PCBs, and polycyclic aromatic hydrocarbons, PAHs) and trace metal concentrations, along with the characterization of the associated prokaryotic communities by the 16S rRNA next generation sequencing, to evaluate possible relationships between pollutant accumulation (e.g., as a stress factor) and prokaryotic community composition in Antarctic sponges. To the best of our knowledge, this approach has been never applied before. Notably, both chemical and microbiological data on H. scotti (a quite rare species in the Ross Sea) are here reported for the first time, as well as the determination of PAHs in Antarctic Porifera. Both sponge species generally contained higher amounts of pollutants than the surrounding sediment and seawater, thus demonstrating their accumulation capability. The structure of the associated prokaryotic communities, even if differing at order and genus levels between the two sponge species, was dominated by Proteobacteria and Bacteroidota (with Archaea abundances that were negligible) and appeared in sharp contrast to communities inhabiting the bulk environment. Results suggested that some bacterial groups associated with H. dancoi and H. scotti were significantly (positively or negatively) correlated to the occurrence of certain contaminants.

Proglacial river sediments are a substantial sink of perfluoroalkyl substances released by glacial meltwater

How climate change will influence the accumulation of pollutants in remote mountainous lakes is poorly understood. Here we collected sediment cores from two glacial lakes (one is small and close to glacier, and the other is large and far from glacier) in the Third Pole and quantified deposition fluxes of perfluoroalkyl substances. The trends of perfluoroalkyl substances fluxes broadly correspond with their historical emissions and phase-out. Besides of emission, glacial meltwater strongly impacts the accumulation of perfluoroalkyl substances in the small lake, while precipitation exhibits great impact on that of the big lake. We then modified the Quantitative Water Air Sediment Interaction model to explore how perfluoroalkyl substances transport along proglacial rivers before entering the big lake and found that river sediments intercept ~13% of perfluoroalkyl substances from glacial meltwater. With climate warming and increased glacial meltwater, proglacial river sediments will play an important role in retaining perfluoroalkyl substances.

Modelling and simulation study on dynamic pollution accumulation process of composite insulator

AbstractWith the widespread application of composite insulators in transmission lines, exploring the accumulation mechanism of pollution particles on composite insulator surfaces is of importance to ensure the safe and steady operation of the power system. Addressing the current theoretical shortcomings, this study categorises the accumulation process of particles on the insulator surface into three stages, namely ‘spatial motion’, ‘surface collision’, and ‘surface motion’. The motion and rotation velocities in a multi‐physics field are calculated in the spatial motion stage. In the surface collision stage, a parameter called ‘neck height’ is introduced to determine the optimum mechanics theory, and the normal deposition criterion is established. For the surface motion stage, the sliding displacement and rolling displacement on the surface are calculated based on the rotation speed of the particles. A dynamic pollution accumulation model of the composite insulator is established based on the normal deposition criterion and tangential displacement. Finally, numerical simulations are performed by using the finite element method. Simulation results show that the proposed model agrees with the actual insulator pollution accumulation, and the deposition model is still applicable for various types of composite insulators operating in different applied voltages. The deposition probability of particles increases with the increasing particle size. In the surface motion stage, particle displacement increases with particle size and wind velocity.

Land reclamation and its consequences: A 40-year analysis of water residence time in Doha Bay, Qatar.

Qatar's rapid industrialization, notably in its capital city Doha, has spurred a surge in land reclamation projects, leading to a constriction of the entrance to Doha Bay. By reducing and deflecting the ocean circulation, land reclamation projects have reduced the effective dispersion of wastewater introduced into the bay and hence degraded the water quality. Here, we assess fluctuations in water residence time across three distinct eras (1980, 2000, and 2020) to gauge the impact of successive land reclamation developments. To do this, we couple the multi-scale ocean model SLIM with a Lagrangian model for water residence time within Doha's coastal area. We consider three different topographies of Doha's shoreline to identify which artificial structures contributed the most to increase water residence time. Our findings reveal that the residual ocean circulation in Doha Bay was predominantly impacted by northern developments post-2000. Between 1980 and 2000, the bay's residence time saw a modest rise, of about one day on average. However, this was followed by a substantial surge, of three to six days on average, between 2000 and 2020, which is mostly attributable to The Pearl mega artificial island development. Certain regions of the bay witnessed a tripling of water residence time. Given the ongoing population expansion along the coast, it is anticipated that the growth of artificial structures and coastal reclamation will persist, thereby exacerbating the accumulation of pollutants in the bay. Our findings suggest that artificial offshore structures can exert far-reaching, non-local impacts on water quality, which need to be properly assessed during the planning stages of such developments.

Effects of Dredging on Nitrogen and Phosphorus Storage Patterns and Retention Mechanisms in Column Core Sediments in the Caohai Region of Dianchi Lake

Dredging is a common technique for managing eutrophication problems in waters, reducing the accumulation of pollutants by removing sediments from the bottom of water bodies. However, dredging can have complex impacts on lake ecosystems, and it is crucial to understand its benefits and mechanisms for the environment. In this paper, the dredged and undredged areas in the Caohai portion of Dianchi Lake were studied to analyze the effects of dredging on nitrogen–phosphorus transport and conversion and changes in nitrogen–phosphorus morphology content and its mechanisms by comparing the nitrogen–phosphorus morphology content and percentage, the nitrogen–phosphorus ratio, and the release contribution of the two areas. It was found that the ratio of stabilized nitrogen (SN) to stabilized phosphorus (SP) in the dredged area was lower than that in the undredged area and the BD-P and TOC content had a large turnaround at the 16–20 cm position of the sediment in the dredged area. The main conclusions were that the dredging would disrupt the internal equilibrium of the lake system for many years, with the greatest effect on the balance of the BD-P in the phosphorus forms of the sediment, and that the column cores of the dredged area at 0 to 16 cm might be newly accumulated sediments after the dredging project. However, with time, the distribution of nitrogen and phosphorus forms in the newly accumulated sediments will gradually reach a new equilibrium. In addition, dredging will also cause significant changes in the retention efficiency of nitrogen and phosphorus in the sediment, and the stable nitrogen and phosphorus forms will be released and transformed into unstable nitrogen and phosphorus forms.

Fate of pharmaceuticals and personal care products like metronidazole, naproxen, and methylparaben and their effect on the physiological characteristics of two wetland plants

Plants play a vital role in the phytoremediation process, attenuating various pollutants. However, the dynamic root uptake and fate of emerging pollutants in plants, along with their effects on plant characteristics, have received limited research attention. This study explores the potential of Chrysopogon zizanioides (Vetiver) and Colocasia esculenta (Taro) in mitigating pharmaceutical and personal care products (PPCPs) - metronidazole (MNZ), naproxen (NAP), and methylparaben (MeP), under hydroponic conditions. Both plants demonstrated similar specific uptake potentials for the target pollutants (5.23 to 5.76 mg/g of biomass dry weight), with pollutant accumulation in plants remaining very low (<10 %). Notably, a substantial fraction of pollutants (66.27 % to 78.42 %) underwent metabolism. Qualitative analysis identified five MNZ and NAP metabolites and six MeP metabolites in plant tissues. Over a 28-day PPCPs exposure, accumulation of reactive oxygen species (ROS) resulted in reduced chlorophyll content, root activity, protein, and carbohydrates, alongside increased oxidative stress levels. The study highlighted distinct accumulation patterns, with NAP (anion) primarily in roots and MeP (cation) and MNZ (neutral) predominantly in aerial parts. Phloroglucinol staining confirmed the intact endodermis (Casparian Strips) in Vetiver roots, indicating symplastic transport of PPCPs to aerial parts. Moreover, significant morphological alterations were observed in plant roots exposed to target pollutants. During recuperation, a decrease in accumulated ROS indicates partial self-recovery from oxidative damage. In conclusion, both Vetiver and Taro emerge as promising candidates for removing specified PPCPs, emphasizing the critical role of addressing emerging contaminants for sustainable development and preserving the environment and human wellbeing.

Effects of street plants on atmospheric particulate dispersion in urban streets: A review

Numerous empirical studies have demonstrated that street trees not only reduce dust pollution and absorb particulate matter (PM) but also improve microclimates, providing both ecological functions and aesthetic value. However, recent research has revealed that street tree canopy cover can impede the dispersion of atmospheric PM within street canyons, leading to the accumulation of street pollutants. Although many studies have investigated the impact of street trees on air pollutant dispersion within street canyons, the extent of their influence remains unclear and uncertain. Pollutant accumulation corresponds to the specific characteristics of individual street canyons, coupled with meteorological factors and pollution source strength. Notably, the characteristics of street tree canopy cover also exert a significant influence. There is still a quantitative research gap on street tree cover impacts with respect to pollution and dust reduction control measures within street spaces. To improve urban traffic environments, policymakers have mainly focused on scientifically based street vegetation deployment initiatives in building ecological garden cities and improving the living environment. To address uncertainties regarding the influence of street trees on the dispersion of atmospheric PM in urban streets, this study reviews dispersion mechanisms and key atmospheric PM factors in urban streets, summarizes the research approaches used to conceptualize atmospheric PM dispersion in urban street canyons, and examines urban plant efficiency in reducing atmospheric PM. Furthermore, we also address current challenges and future directions in this field to provide a more comprehensive understanding of atmospheric PM dispersion in urban streets and the role that street trees play in mitigating air pollution.

Anthropogenic multipollutant input to the offshore South China Sea

The remote region of the South China Sea (SCS), situated far from urban mainland areas, is commonly perceived to experience minimal pollution. However, this may evolve into a considerably polluted region owing to increasing anthropogenic pollutants. In this study, we employ a multidisciplinary approach to analyze the surface sediments collected from the offshore area of the southern SCS. Our aim is to explore potential anthropogenic pollutants, their interactions, and the related controlling factors. This research endeavors to enhance our understanding of the current pollution status in the SCS and help making relevant policy management decisions. Comparison with previous reports reveals that now, the area is more extensively and increasingly contaminated by petroleum hydrocarbons and heavy metals (Cd and As) than before. For the first time, we report the recognition of coprostanol and long-chain alkyl mid-chain ketones, unveiling the noticeable incorporation of sewage fecal matter and biomass burning into offshore sediments. Moreover, sedimentary multipollutants (except ketones) exhibit strong correlations with terrestrial elements and fine-sized particles, displaying a roughly high-west/low-east spatial variability in pollutant accumulation or enrichment. These signatures evidently demonstrate the major impact of river discharges (e.g., the Mekong River to the west and the Pearl and Red Rivers to the north) on the SCS. They have hydrodynamic effects on the subsequent basin-wide dispersal of pollutants, driven by monsoon-induced large- and regional-scale currents. The different behavior of burning-related ketones may be partly due to their aerosol form, leading to atmospheric transportation. Because anthropogenic multipollutants pose compounded threats, exacerbating oceanic warming and acidification to marine ecosystems such as the widespread coral reefs in the southern SCS, scientific management of urban emissions is required to mitigate ecosystem degradation in the Anthropocene era.