Particulate Surface Research Articles

Solution and Solid-State Behavior of Amphiphilic ABA Triblock Copolymers of Poly(acrylic acid-stat-styrene)-block-poly(butyl acrylate)-block-poly(acrylic acid-stat-styrene)

A combination of statistical and triblock copolymer properties is explored to produce stable aqueous polymer dispersions suitable for the film formation. In order to perform an extensive structural characterization of the products in the dissolved, dispersed, and solid states, a wide range of symmetrical poly(acrylic acid-stat-styrene) x -block-poly(butyl acrylate) y -block-poly(acrylic acid-stat-styrene) x , poly(AA-st-St) x -b-PBA y -b-poly(AA-st-St) x , (x = 56, 108 and 140, y = 100-750; the AA:St molar ratio is 42:58) triblock copolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) solution polymerization using a bifunctional symmetrical RAFT agent. It is demonstrated that the amphiphilic statistical outer blocks can provide sufficient stabilization to largely hydrophobic particles in aqueous dispersions. Such a molecular design provides an advantage over copolymers composed only of homoblocks, as a simple variation of the statistical block component ratio provides an efficient way to control the hydrophilicity of the stabilizer block, which ultimately affects the copolymer morphology in solutions and solid films. It was found by small-angle X-ray scattering (SAXS) that the copolymers behaved as dissolved chains in methylethylketone (MEK) but self-assembled in water into stable and well-defined spherical particles that increased in size with the length of the hydrophobic PBA block. These particles possessed an additional particulate surface structure formed by the statistical copolymer stabilizer block, which self-folded through the hydrophobic interactions between the styrene units. SAXS and atomic force microscopy showed that the copolymer films cast from the MEK solutions formed structures predicted by self-consistent field theory for symmetrical triblock copolymers, while the aqueous dispersions formed structural morphologies similar to a close-packed spheres, as would be expected for copolymer particles trapped kinetically due to the restricted movement of the blocks in the initial aqueous dispersion. A strong correlation between the structural morphology and mechanical properties of the films was observed. It was found that the properties of the solvent cast films were highly dependent on the ratios of the hard [poly(AA-st-St)] and soft (PBA) blocks, while the aqueous cast films did not show such a dependence. The continuous phase of hard blocks, always formed in the case of the aqueous cast films, produced films with a higher elastic modulus and a lower extension-to-break in a comparison with the solvent-cast films.

Atmospheric chemistry and cancer risk assessment of Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs over a semi-arid site in the Indo-Gangetic plain.

Polycyclic Aromatic Hydrocarbons (PAHs) and Nitro-PAHs were collected over a year at a traffic dominated site in Agra, to determine the dominant partitioning mechanism. During the entire sampling period, total PAHs and Nitro-PAHs were 3465±3802 and 26.1±25.9ngm-3 respectively. The gas-particle partitioning behavior of PAHs was studied by applying the Pankow model, Absorption model, and Dual model. Amongst all the partitioning models, the Dual model fits well and indicates that the partitioning of PAHs at the traffic site in Agra depends on both the physical adsorption of PAHs on the Total Suspended Particulate (TSP) surface and absorption of PAHs into the organic layer present on the TSP surface. Pankow model indicates that PAHs are emitted from the source close to the sampling point and due to this PAHs do not get enough time to get partitioned in between both the phases. Incremental lifetime Cancer Risk (ILCR) shows that adults and children are more prone to cancer risk in comparison to infants for both PAHs and Nitro-PAHs. Cancer risk by inhalation was minimum in comparison to both ingestion and dermal exposure. Nitro-PAHs in the particulate phase were high enough to exceed the minimum permissible limit (10-6) of causing cancer by ingestion and dermal exposure.

An Analysis of the Aerosol Lifecycle Over India: COALESCE Intercomparison of Three General Circulation Models

AbstractAtmospheric aerosols or atmospheric particulate matter affects climate variables like temperature and rainfall, agricultural productivity, soil, and human health. We evaluated aerosol lifecycle over India via simulations (2005–2014) from three general circulation models under the COALESCE project (carbonaceous aerosol emissions, source apportionment, and climate impacts; Venkataraman et al., 2020, 10.1175/bams‐d‐19‐0030.1). The ECHAM6.3‐HAM2.3, CAM5.3, and NICAM‐SPRINTARS simulations use identical regional emissions (from the Speciated Multi‐pollutant generator, SMoG‐India‐v1). Satisfactory model simulations of meteorological variable magnitudes and seasonal cycle have been achieved partly from the adoption of nudging. Estimations of anthropogenic aerosol, aerosol optical depth (AOD), and particulate matter surface concentrations are significantly improved from (a) dust tuning (b) use of satellite‐derived organic aerosol to carbon ratio, and (c) nudged meteorology to capture variables influencing the production of secondary sulfate. Larger wintertime under prediction (−30% to −60%) results from over prediction of seasonal planetary boundary layer height and the absence of secondary ammonium nitrate and organic aerosols. Vertical dispersion to higher altitudes than in observations calls for improved modeling of vertical mass flux representation. Carbonaceous aerosol residence time and AOD fraction larger than global mean values in India, with a seasonal predominance in the autumn and winter seasons can be explained by enhanced regional emissions from residential biofuel cooking, agricultural stubble burning, and traditional informal industries like brick production.

Regional joint PM2.5-O3 control policy benefits further air quality improvement and human health protection in Beijing-Tianjin-Hebei and its surrounding areas

Beijing-Tianjin-Hebei and its surrounding areas (hereinafter referred to as “2+26” cities) are one of the most severe air pollution areas in China. The fine particulate matter (PM2.5) and surface ozone (O3) pollution have aroused a significant concern on the national scale. In this study, we analyzed the pollution characteristics of PM2.5 and O3 in “2+26” cities, and then estimated the health burden and economic loss before and after the implementation of the joint PM2.5-O3 control policy. During 2017–2019, PM2.5 concentration reduced by 19% while the maximum daily 8 hr average (MDA8) O3 stayed stable in “2+26” cities. Spatially, PM2.5 pollution in the south-central area and O3 pollution in the central region were more severe than anywhere else. With the reduction in PM2.5 concentration, premature deaths from PM2.5 decreased by 18% from 2017 to 2019. In contrast, premature deaths from O3 increased by 5%. Noticeably, the huge potential health benefits can be gained after the implementation of a joint PM2.5-O3 control policy. The premature deaths attributed to PM2.5 and O3 would be reduced by 91.6% and 89.1%, and the avoidable economic loss would be 60.8 billion Chinese Yuan (CNY), and 68.4 billion CNY in 2035 compared with that in 2019, respectively. Therefore, it is of significance to implement the joint PM2.5-O3 control policy for improving public health and economic development.

Core shell coatings for nuclear thermal propulsion cermets

Magnetron sputtering has been employed to provide conformal tungsten coatings from approximately 70 to 540 nm thicknesses over yttria stabilized zirconia (YSZ) powders. Through a rotating vessel, the powder was continually cascaded exposing its surface enabling the line-of-sight cathode tungsten target to deposit over the entire surface. With increasing coating thickness, a particulate surface morphology developed. These tungsten particulates were plate-like in morphology and faceted in some cases. The formation of these features is contributed to the continual low energy impacts between the hard YSZ powders during deposition as well as the adhesion and de-adhesion of the coatings connecting particle clusters. The results of this work demonstrate the ability of sputter deposition to create refractory coatings for cermet fuels utilized in nuclear thermal propulsion, as well as broader applications where core-shell powder fabrication is needed.

Weakened Haze Mitigation Induced by Enhanced Aging of Black Carbon in China

A great challenge for haze pollution mitigation with the existing emission control measures in China is ozone (O3) increase. The chemical processes leading to weakened haze mitigation are still poorly understood. Our work identifies the enhanced aging chemistries of black carbon (BC) with increasing O3 as an essential driver to weaken haze mitigation based on field observations during autumn/winter haze periods in 2014 and 2018 in North China Plain. The enhanced atmospheric oxidation capacity induced by increasing O3 promotes the initial aging of accumulated fresh BC from continuous emission under haze pollution conditions and consequently improves the hygroscopicity of BC-containing particles to provide more particulate surfaces and volumes for aqueous and heterogeneous chemistries. The enhanced BC aging amplifies PM2.5 concentrations by ∼20%, which can be broken by concurrent reductions in multipollutant emissions (i.e., BC, nitrogen oxides, and volatile organic compounds), especially from residential and industrial sources. Moreover, enhanced BC aging implies an adverse effect of O3 increase on climate change. Observationally enhanced BC aging will help to constrain estimations of the interactions among O3 increase, haze pollution, and climate warming in recent years in China.

New Polarimetric Data for the Galilean Satellites: Europa Observations and Modeling

This paper is dedicated to a long-standing problem of the shape of the negative branch of polarization (NBP) for Jupiter's moon Europa, determination of which is crucial for the characterization of the icy regolith on this satellite and similar objects, as well as for further progress in understanding light scattering by particulate surfaces. To establish the shape of Europa's NBP, in 2018–2021 we accomplished high-precision disk-integrated polarimetry of Europa in the UBVR I bands using the identical two-channel photoelectric polarimeters mounted on the 2.6 m Shajn reflector of the Crimean Astrophysical Observatory and the 2 m telescope of the Peak Terskol Observatory. We found that the polarization dependence on the phase angle in each filter is an asymmetric curve with a sharp polarization minimum at phase angle , after which the polarization degree gradually increases to positive values, passing the inversion angle at α inv ≈ 6° − 7°. Within the error limits, the parameters P min, , and α inv of the NPB are independent of the wavelength in the visible spectrum. The polarization curve clearly demonstrates the so-called polarization opposition effect (POE). Our analysis of the previous and new polarimetric observations of Europa allows us to conclude that the POE is caused by coherent backscattering of sunlight on microscopic icy grains covering Europa’s surface. Computer modeling with the numerical radiative transfer coherent backscattering method demonstrates that the best fit to the polarimetric observations and geometric albedo of Europa is provided by a regolith layer of elementary single-scattering albedo ∼0.985 and extinction mean free path length 2π l/λ eff ≈ 150, λ eff representing the effective wavelength in the UBVR I spectral bands.

Sources and Distribution of Organic Matter in Coastal Area of Muang Chonburi District, Eastern Thailand: Using Carbon and Nitrogen Stable Isotopes

The sources and spatial distribution of organic matter were investigated in the nearshore area receiving untreated urban wastewater and offshore areas containing bivalve mariculture in Muang Chonburi District. Content, elemental, carbon, and nitrogen isotopic analyses in particulate organic matter (POM) and surface sediments were performed. We found particulate organic carbon (POC), δ13C, and δ15N of POM ranging from 435.0-5,247.7 µg/L, -27.7 to -22.0 ‰, and 1.7-8.6 ‰, respectively, whereas total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N in sediment were 3.5-76.9 µg/g, 0.8-8.3 µg/g, -25.7 to -22.9 ‰ and 2.6-6.0 ‰, respectively. These values show significant differences between nearshore and offshore sampling stations wherein accumulation of organic matter was high in the nearshore and decreased with greater distance offshore, with some retained in the bivalve farming area. The results from a mixing model indicated that organic matter in POM and sediment were initially derived from anthropogenic organic matter. In contrast to the offshore water which had organic matter derived from marine organic matter. This study highlights the distribution of anthropogenic organic waste released to coastal waters with plenty of bivalve farms such as green mussels and oysters. The results can be used to advise national strategies regarding bivalve aquaculture zoning and seafood safety policies going forward.

The effect of aspect changes on Near-Earth Asteroid phase curves

ABSTRACTPhase curves of asteroids are typically considered to depend solely on the scattering properties of airless particulate surfaces and the size of the object being studied. In this study, we demonstrate the additional dependence of phase curves on object shape, rotation pole orientation, and viewing geometry over an apparition. Variations in the phase curve of near-Earth asteroid (159402) 1999 AP10 over its apparition from 2020 July to 2021 January are verified to be due to aspect changes over the apparition. This is achieved through shape modelling of the asteroid and simulation of the phase curve over the apparition. We present simulations of asteroid phase curves over a range of geometries to understand the potential magnitude of this aspect effect, and under which circumstances it can begin to dominate in the phase curves. This dependence on aspect may introduce significant additional uncertainty in the properties derived from phase-curve data. We provide and demonstrate software code to estimate the aspect-related uncertainty in near-Earth asteroid phase curves through simulation and model fitting of a randomly generated sample of ellipsoidal asteroid models over the observed viewing geometry. We demonstrate how ignoring this effect may lead to misleading interpretations of the data and underestimation of uncertainties in further studies, such as those in the infrared that use phase curve derived parameters when fitting physical properties of an asteroid.

Binding and transport of Cr(III) by clay minerals during the Great Oxidation Event

A spike in chromium (Cr) abundance above crustal background in iron formations post-dating the Great Oxidation Event (ca. 2.5-2.3 billion years ago) has been suggested to reflect the evolution of terrestrial aerobic pyrite and siderite oxidation and the initiation of widespread acid rock drainage that would enhance Cr transport from terrestrial weathering environments to the oceans. However, it remains unclear whether Cr was transported in a soluble form (as Cr(III) or Cr(VI)), or bound to particulate surfaces. Here, we experimentally investigate the binding mechanisms of Cr(III) – the typical oxidation state associated with primary igneous minerals such as chromite – to three common soil clay minerals (kaolinite, illite, and montmorillonite) using extended X-ray adsorption fine structure (EXAFS) spectroscopy. Our results demonstrate that Cr(III) precipitates on the clay surfaces over a pH range of 6 to 8 as guyanaite (β-CrOOH) due to the replacement of surface Al-octahedra by paired Cr(III) octahedra. Bidentate bonding with a Cr-Cr interatomic distance of 3.43-3.51 Å indicates the incorporation of Cr(III) into the clay structure. A comparison between Cr(III) adsorption/precipitation onto the three clays and the desorption of Cr(III) from Cr(III)-spiked clays shows that kaolinite has the highest retention capacity for Cr(III), a predictable result given that an entire Al-octahedral sheet is exposed for Cr(III) binding, while illite and montmorillonite only have Al-edge sites. Moreover, Cr(III) was essentially immobilized in our experiments except under very acidic conditions (pH<2). Extending our results to the interpretation of the Cr record in iron formations, we suggest that under intense chemical weathering conditions, not only did acidity promote the solubilization of Cr(III) from primary Cr-bearing minerals, but that parent rocks were more systematically weathered to an advanced state dominated by kaolinite – creating ideal conditions for Cr adsorption. Erosion of regolith that scavenged mobilized Cr(III) could then facilitate transport of Cr(III)-bearing kaolinite to coastal environments where it contributed to the super-crustal Cr abundances above detrital background preserved in ca. 2.5-2.0 Ga iron formations.

Coating Processes of Pharmaceutical Applicability: A Glimpse

Presentation of manuscript is aiming to furnish glimpse on coating processes. Coating is process of snugly covering substrate surface with coating materials (CoM). In due course coating process has gradually developed from sugar-coating to non-aqueous film-coating to aqueous film-coating to specialised-coating processes. In second half of past century sugar-coating was first choice for pharmaceutical industry. Lengthy and tedious processing along with issues of skilled-operator inherited to sugar-coating compelled them to spring-up and improve film-coating. From past five decades, volatile organic solvent (VOS) are preferred over water in film-coating. Momentum for using aqueous solvent in film-coating gets accelerated from past few decades. Nowadays these replacing the VOS based film-coating processes as later inherit issues relating toxicity; safety; worker hygiene &amp; safety; environmental pollution; etc. During process of finding novelty of coating another exploited sphere is coating of particulate substrate surfaces with CoM is to confer them worthy functionalities and applications. In this area both wet- &amp; dry-coating process finds applicability thru modifying and/or altering innate properties of substrate, physically and/or chemically. Dry-coating process basically comprises specialised and novel process &amp; technologies. Nowadays there available numerous conventional, specialised, and novel coating processes. Amongst them state-of-art process are hot-melt coating (HMC) process, aqueous film-coating process, aerosolized coating process, Supercell® coating process, gas-/ vapour-phase process, photo curable coating process, electrical-electrostatic deposition process, Resonant acoustic coating process, thermal and mechanical process, thermo-mechanical process, fluidised-bed processes, etc. Herein conventional, specialised, and novel coating processes are briefed, to update professionals.&#x0D; Keywords: Coating, film-coating, novel, process, specialised.

Necroptosis contributes to airborne particulate matter-induced ocular surface injury

In this study, we explored the role of necroptosis in the pathogenesis of ocular surface injury caused by airborne particulate matter (PM). Human corneal epithelial (HCE) cells and mouse ocular surface were treated with PM exposure and compared with non-exposed groups. The expression of necroptosis-related proteins was measured by immunoblotting in HCE cell groups. Cell damages were detected using CCK-8, flow cytometry, and immunofluorescence staining. In the mouse model, hematoxylin and eosin (H&E) staining and corneal fluorescein sodium staining were assessed. In addition, the expression of inflammatory cytokines and mucin were examined via Enzyme-linked immunosorbent assay (ELISA), immunofluorescence staining and/or quantitative RT -PCR (qRT-PCR), both in vitro and in vivo. Our research showed that PM exposure may trigger HCE cell damage via necroptosis. Necrostatin-1(Nec-1), one of the specific inhibitors of necroptosis, can markedly reduce PM-induced HCE cell damage. HCE cell damage markers included decreased cell viability, increased intracellular reactive oxygen species (ROS) levels, and loss of mitochondrial membrane potential. At the same time, Nec-1 inhibited the increased inflammatory cytokines and the decreased mucin expression caused by PM exposure in HCE cells. Nec-1 also reduced corneal inflammation and mucin underproduction in mouse ocular surface after PM exposure. Our study demonstrated that necroptosis is involved in the pathogenesis of PM exposure-related ocular surface injury, including inflammation and insufficient mucin production in the cornea, which can be rescued by inhibitor Nec-1. This suggests Nec-1 could be a novel therapeutic target for ocular surface disorders, especially dry eye disease, which is caused by the exacerbation of airborne PM pollution.

Characteristics and health risk assessment of fine particulate matter and surface ozone: results from Bengaluru, India.

Urban air pollution is a complex problem, which requires a multi-pronged approach to understand its dynamics. In the current study, various aspects of air pollution over Bengaluru city were studied utilizing simultaneous reference-grade measurements (during the period July 2019 to June 2020) of fine particulate matter mass concentration (PM2.5), aerosol black carbon mass concentrations (BC), and surface ozone (O3) concentrations. The study period mean PM2.5, BC, and O3 were observed to be 26.8 ± 11.5 µg m−3, 5.6 ± 2.8 µg m−3, and 25.5 ± 12.4 ppb, respectively. Statistical methods such as principal component analysis, moving average subtraction method, conditional bivariate probability function, and concentration weighted trajectory analysis were performed to understand the dynamics of air pollution over Bengaluru and its long-range transportation pathways. Some of the major findings from the statistical analyses include (i) contrasting association in BC versus O3 and PM2.5 versus O3; (ii) around one-fourth of the observed receptor site BC was contributed by local sources/emissions; and (iii) the source locations potentially contributing to BC and PM2.5 were spatially different. In Bengaluru, long-term exposure to PM2.5 resulted in around 3413, 3393, 1016, and 147 attributable deaths for the health endpoints chronic obstructive pulmonary disorder, ischemic heart disease, stroke, and lung cancer, respectively. Long-term exposure to O3 resulted in around 155 attributable deaths for respiratory diseases, as estimated by the AirQ + model. Finally, the limitations of the study in terms of data availability and analysis have been detailed.Supplementary informationThe online version contains supplementary material available at 10.1007/s10661-022-09852-6.

Critical material designs for mucus- and mucosa-penetrating oral insulin nanoparticle development

ABSTRACT Subcutaneous and pulmonary insulin is associated with medical and pharmaceutical complications. Oral insulin mimics physiological glucose regulation with reduced hypoglycemia and coma risks. Nanoparticles are advocated as oral insulin carrier to overcome intestinal absorption barrier. Their insulin bioavailability and blood glucose lowering performances are hampered by inefficient mucus and mucosa transport of nanoparticles. This review discusses critical materials used in oral insulin nanoparticle design to address mucus and mucosa penetrating hurdles. It highlights intestinal receptor targeting, biomimetic virus mimicking, particulate surface charge switching, coat-core detachment, and combination approaches developed through material sciences. Mucus penetration favors particles with hydrophilic/amphiphilic surfaces with no net charges. Mucosa penetration shows a preponderance for hydrophobic or positively charged surfaces with intestinal receptor binding affinity. Materials with switchable physicochemical properties along with mucus-mucosa transit require research exploration, with consideration of their influences on endocytosis, lysosomal escape, exocytosis, and intestinal receptor upregulation.

A non-motorized spectro-goniometric system to measure the bi-directional reflectance spectra of particulate surfaces in the visible and near-infrared.

Reflectance spectroscopy is a powerful tool for remotely identifying the compositional and physical properties of surface materials. Due to the anisotropic scattering nature of most surfaces, the spectral features, including the absolute reflectance value, spectral slope, and band depth, are influenced by illumination and viewing configurations. Therefore, it is important to understand how spectral features vary with illumination and observation geometries for various particulate surfaces through laboratory measurements. Here, we describe a non-motorized spectro-goniometric system capable of measuring the bi-directional reflectance of particulate surfaces in the upper hemisphere in the wavelength range from 350 to 2150nm. The incident and the viewing zenith angles can be varied from 0° to 55° and from 0° to 70°, respectively. The relative viewing azimuth angle can be varied from 0° to 360°. Measurements on Labsphere Spectralon agree well with measurements done with other instruments. We also present measurement results on two typical planetary analog materials, the JSC-1A Martian soil simulant and the JSC-1A lunar regolith simulant.

Self-cleaning durability assessment of TiO2/SiO2 photocatalysts coated concrete: Effect of indoor and outdoor conditions on the photocatalytic activity

A self-cleaning nanostructured TiO2 coating has demonstrated the capacity to mitigate undesired effects from air pollution. Not only it reduces the deterioration of building materials but may also prevent certain pollution-related human health problems. In this study, mesoporous TiO2/SiO2 photocatalysts were synthesized in order to produce self-cleaning and long-lasting coatings that meet the necessary requirements for outdoor applications. The synthesized products were sprayed on concrete substrates and their self-cleaning and air depolluting capabilities were evaluated. The former one as a function of methylene blue (MB) and soot degradation and the latter, according to nitrogen oxides reduction. The coatings proved to have high photocatalytic activity, and their efficiency was enhanced as TiO2 loadings were increased. Thus, after the first 60 min of their irradiation by UV–vis light, the photocatalysts ST1 and S4T had removed 79% and 95% of the MB, respectively. These coatings presented particulate surfaces that provided more surface area and porosity, which are key factors for a high photocatalytic activity. Moreover, the same samples after 104 h of irradiation exhibited 38% and 49% conversion of total NO, respectively. While E503, a commercially available photocatalyst, produced coating cracked surfaces and a total MB degradation of just 50% after 60 min of irradiation as well as 35% of NO conversion after 104 h of irradiation. The TiO2/SiO2 coatings’ photocatalytic efficacy remained practically invariable after four months of exposure to real-life conditions and three MB degradation cycles. After the outdoor durability tests, the coated surfaces exhibited a practically unchanged structure, which confirms their long-lasting efficiency.

Influence of major typhoons on ocean, atmosphere and air quality of Northwest Pacific during August 2020

Tropical storms (TSs)/Typhoons (TYs) in the Northwest Pacific (NWP) region are one of the most devastating natural hazards, which cause large-scale impacts on human life and infrastructure. In August 2020, a total of 9 tropical storms were identified by International Best Track Archive for Climate Stewardship (IBTrACS) in the NWP region. These TSs/TYs made their landfall over the coastal parts of China, North Korea, and South Korea, while none of them made their landfall over Taiwan. These conditions were unique in recent years and induced drought conditions in Taiwan during 2020. We have carried out a three-dimensional analysis of oceanic, atmospheric, and meteorological parameters for the evaluation of changes associated with typhoons during August 2020. The model, satellite, and ground observations data have been used for the assessment of the impact of these TS/TYs on the ocean, atmosphere, and air quality. The rise in ocean temperature (1 °C–2 °C) was observed even at the depth of 100 m. Strong upwelling of the ocean water in the NWP originated a change in the mixed layer depth and also has affected the salinity in South China, East China, and the Philippines Sea. The strong convective forces during the storm conditions produced a prominent rise in CO and Ozone concentration. These typhoons also affected the air quality of Taiwan during August 2020. The transboundary air pollutants triggered the enhancement in particulate matter (PM1.0 and PM2.5) and surface ozone over Taiwan, which resulted in major health hazards to a large population.

Archaeal tetraether lipids and their biphytane carbon isotope composition in sediments along an estuarine biogeochemical gradient

The stable carbon isotopic composition of Thaumarchaeota-produced crenarchaeol (δ13Ccren) is thought to reflect the δ13C of dissolved inorganic carbon (DIC) and is valuable in carbon cycle research. Recently, an isotope flux-balance model was proposed that δ13Ccren is dependent on passive CO2 uptake and a slow rate of intracellular conversion to HCO3−, which has been validated in open ocean environments. However, further studies are required in environments with larger ranges of aqueous CO2 and diverse archaeal communities to examine whether the δ13Ccren value could still be predicted by the model. Here, we report δ13C values of biphytanes chemically released from the archaeal tetraether lipids (i.e., GDGTs) in sediments along a transect exhibiting shifts in the archaeal community and showing gradients of salinity, pH, and CO2 in the Pearl River Estuary, South China. Methanogenic and methanotrophic Euryarchaeota are present in the upper estuary, although not significant, as revealed by the elevated relative abundances of GDGT-0 and higher values of methane index in suspended particulate matter (SPM) and surface sediments, as well as the more 13C-depleted C40:0, C40:1, and C40:2 biphytanes than the C40:3 biphytane released from sedimentary GDGTs. Toward the lower estuary and coastal sea, GDGT distributions in SPM and sediments tend to indicate archaeal communities under normal marine conditions. However, there are still differences in δ13C values between C40:0 and C40:3 biphytanes by up to 2.4‰ in sediments, although C40:1, C40:2, and C40:3 were similar in δ13C, likely due to the existence of marine group II Euryarchaeota. Along such a physicochemical and biogeochemical gradient, the values of sedimentary δ13C40:3 increase monotonically with the increase of mean annual pH and the decrease of mean annual CO2. This phenomenon resembles the reported δ13CGDGT profiles, along with the variations in pH and CO2, in water column in the open ocean, and hence consistent in direction with the isotope flux-balance model for Thaumarchaeota lipids. However, our estimated apparent biosynthetic isotope effect (εAr) of crenarchaeol, ranging from 15.2‰ to 19.7‰, is mostly lower than those estimated in the open ocean. With the constraints of thaumarchaeal growth rates in such a dynamic estuarine environment as well as those in the open ocean, we suggest slight reductions in catalytic efficiency and intracellular kinetic isotope effect of intracellular CO2 hydration relative to previously employed values. Such modifications would slightly change the sensitivities of εAr to archaeal growth rate and ambient CO2 concentration but might be more suitable for variable hydrology and community environments.

Major Ambient Air Pollutants and Toxicity Exposure on Human Health and Their Respiratory System: A Review

Indoor and outdoor air pollution is causing environmental and health issues globally. It is more challenging mainly in developing countries like India, china, and others.According to recent World Health Organization (WHO) reports, nearly 4.2 million people die prematurely because of AAP (Ambient Air Pollution). Air pollution is made up of a variety of contaminants, including gases, liquids, heavy metals in the air, and particulate matter. Suspended particulate matter (SPM), surface ozone (O3), sulfur dioxide (SO2), nitrogen oxides (NO2), and other contaminants have become major environmental threats to plant health. These pollutants also have an effect on human health because they affect the consistency of the air we breathe. They usually cause inflammation in the upper respiratory tract, resulting in cough and shortness of breath. These are also significant contributors to the exacerbation of current respiratory conditions like asthma and chronic obstructive pulmonary disease. Epidemiological, toxicological, and clinical research all support the connection between air pollution and increased incidence and severity of respiratory and cardiovascular diseases. This pollution is a major public health problem in the locations where maximum pollution sources exist. To improve air quality and reduce the adverse effects of airborne toxicity due to AAP on human health, significant approaches are needed. The main objective of this review article is to provide evidence on the adverse effects of AAP on human health, as well as to make recommendations to policymakers on how to minimize exposure to this risk factor. Only public awareness combined with a multidisciplinary approach by scientific specialists will be able to handle this problem; national and international organizations must address the rise of this threat and suggest long-term remedies.

Exposure to PM4 in Homes with Tobacco Smoke in and around Katowice, Poland

The results of a PM4 (airborne particles with an aerodynamic diameter less than 4 µm) study in Katowice and in the surrounding area in homes with and without environmental tobacco smoke (ETS) are presented. It was found that the average concentration of PM4 inside the homes with ETS was between 126 µg m−3 (in Jaworzno) and 208 µg m−3 (in Katowice)—significantly higher than in the homes without smokers (55–65 µg m−3). The mean of the indoor to outdoor ratios (I/O) for PM4 varied greatly, ranging from 0.6 in the apartments without smokers in Katowice to 5.2 in the homes with smokers in Jaworzno. The highly polluted by ETS indoor air causes children aged 14–15 living in these homes to inhale from 2.5 to 6.6 mg of PM4 more per day than their peers living in non-ETS homes. X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemical composition of the studied indoor airborne particles. Carbon, including elemental carbon, and oxygen-containing species dominated the particulate surface, with traces of Si, N, S, Na, Al, Zn, and K present. The surface layer of PM4 from the homes with ETS contains significantly more carbon and less oxygen than the airborne particles collected in the homes without smokers, which can be explained by the high emission of carbon during tobacco smoking.