OC Concentrations Research Articles

Influence of Organic Carbon from Weathered Sediments on Triclocarban Distribution in Environmental Aqueous Systems

In this study, the chemical distribution of triclocarban (TCC), in natural aqueous systems, between water and sediment, with different chemical compositions of the aqueous phase and different percentages of organic carbon (OC%) in the sediments is presented. The influences of the temperature, of the composition of the aqueous matrices of natural waters and (OC%) in the sediment over the solubility of triclocarban, and its distribution coefficient Kd values were studied. log KD at 25 °C varied between 1.94 and 3.27 for a sediment with 5.50% OC and between 3.95 and 5.93% for a sediment with 6.75% OC, in the studied aqueous systems, with different concentrations of OC in the sediment.

High-Resolution Modeling of Air Quality in Abidjan (Côte d’Ivoire) Using a New Urban-Scale Inventory

In West African cities, the impacts of the air quality on the health of the population is expected to increase significantly in the near future. For the first time to our knowledge, we conducted a high-resolution modeling study over Abidjan (Côte d’Ivoire) using the WRF-Chem model and the simplified GOCART model to simulate carbonaceous aerosols BC and OC, sulfate, dust, sea salt, PM2.5, and PM10. The simulations were carried out during January and February 2019, a period over which there are databases of observations available. The DACCIWA inventory provided anthropogenic emissions at the regional scale, whereas a new emission inventory has been developed for the city of Abidjan. In 2019, the emissions were 4986.8 Gg for BC, 14,731.4 Gg for OC, and 7751.6 Gg for SO2. Domestic fires were the primary OC source (7719.5 Gg), while road traffic was the largest BC emitter (2198.8 Gg). Our modeling results generally overestimate urban particle concentrations, despite having a better agreement for those based on the inventory of the city of Abidjan. Modeled concentrations of BC are higher in administrative centers due to road traffic, while OC concentrations are significant in densely populated neighborhoods.

Natural colonizers effectively restore heavy metal polluted wasteland

In India, ∼30% of total land is degraded due to pollution, salinization, and nutrient loss. Change in soil-quality at urban waste-dumping site prior and after cow-dung amendment was compared with control agriculture soil. The soil at waste-dumping site had elevated pH, EC, temperature and lowered OC and NPK concentrations when compared to control. Polymetallic pollution of Cr, Cd, Pb, and Ni beyond permissible limits was obtained. Cow-dung amendment restored soil physicochemical properties at the waste-dumping site, with increasing soil moisture, CEC and OC; however, a slight change in soil bulk-density and heavy-metal concentration post-amendment was noted. The seven natural colonizers present at the waste-dumping site accumulated more metals in roots than shoots. Datura innoxia had maximum bioaccumulation of Cr, Calotropis procera of Cd and Ni and Parthenium hysterophorus of Pb in roots. All these plants had Bioacccumulation factor (BAfroot )>1 and translocation factor (Tf) <1 for Cd and serve as its phytostabilizer except Calotropis procera which had BAfroot >1 and Tf >1 and is identified as a phytoextractor for Cd. Cow-dung amendment alone appeared to be insufficient and additionally the revegetation of natural colonizers is recommended for effective reduction in heavy metal load and improving overall soil health at wasteland. Such eco-restoration may also minimize risks to biodiversity in India.

Impact of peri-urban forest fires on air quality and aerosol optical and chemical properties: The case of the August 2021 wildfires in Athens, Greece

Wildfires occurring near urban areas are known to have exceedingly detrimental impacts on the environment, air quality, economy and human health. In this framework, this study examines the effects of peri-urban forest fires on atmospheric chemical composition, and aerosol physical-optical properties in Athens, Greece, during August 2021. Satellite imagery and air mass trajectories showed advection of intense smoke plumes over Athens from three forest fires persisting for 10 days in the greater Athens area and in Central Greece (Euboea). During August 1–20, 2021, daily PM2.5 concentrations ranged from 8.9 to 78.7 μg m−3, and were associated with high OC levels (2.3–27.8 μg m−3), while BC and BCbb concentrations on smoke-impacted days were 2.6 μg m−3 and 1.0 μg m−3, respectively (2–3 times higher than August mean levels). During the peak of biomass burning (BB) smoke transport over Athens, daily-average scattering and absorption coefficients at short wavelengths maximized at 313 Mm−1 and 171 Mm−1, respectively. There was also a large impact of ambient BrC (brown carbon) absorption (60 Mm−1), while the OC/EC ratio exhibited characteristically low values (3–4), linked to flaming combustion (modified combustion efficiency of 0.97–0.99). The absorption Ångström exponent (1.38) and single scattering albedo (0.74) indicated highly absorbing BB aerosol, deviating from the normal summer patterns. BB-tracers like nssK+ displayed strong correlations with OC, EC and BC concentrations, as well as with scattering and absorption coefficients. However, forest fires drastically modified the levels of additional chemical species, with enhancements observed for Ca2+, NO3−, Cl−, and for organic aerosol (OA) components such as BBOA and less-oxidized oxygenated OA (LO-OOA). Since under climate change conditions, the Mediterranean is anticipated to experience a dramatic rise in the frequency and intensity of wildfires, the results highlight the necessity for prevention and mitigation policies to safeguard urban air quality.

Do Organochlorine Contaminants Modulate the Parasitic Infection Degree in Mediterranean Trout (Salmo trutta)?

We investigated the occurrence of organochlorine pollutants (OCs) in the muscle of brown trout and evaluated their potential modulation of parasite infection. The toxicological risk for consumer health was assessed, too. Trout were collected from the Sila National Park (Calabria region, South of Italy). The highest concentrations emerged for the sum of the 6 non-dioxin-like (ndl) indicator polychlorinated biphenyls (Σ6ndl-PCBs), followed by the 1,1,1-trichloro-2,2-di(4-chlorophenyl)-ethane (DDT), dioxin-like PCBs, hexachlorobenzene (HCB), and dieldrin. Measured on lipid weight (LW), the mean value of Σ6ndl-PCBs amounted to 201.9 ng g-1, that of ΣDDTs (the sum of DDT-related compounds) to 100.2 ng g-1, with the major contribution of the DDT-metabolite p,p'-DDE which was detected in all sample units (97.6 ng g-1 on average). Among dioxin-like congeners, PCB 118 showed the highest mean concentration (21.96 ng g-1 LW) and was detected in all sample units. Regression analysis of intestinal parasites on OC concentration was performed, controlling for two potential confounding factors, namely sex and sexual stage. The results evidenced the existence of interactions between the dual stressors in the host-parasite system in the wild. A negative and statistically significant correlation was estimated, suggesting that OCs may decrease parasite infection degree. Regarding the toxicological risk evaluation, OC concentrations were consistently below the current European Maximum Residue Limits.

The relationship between coronary artery calcification and bone metabolic markers in maintenance hemodialysis patients

BackgroundTo study the influencing factors for coronary artery calcification (CAC) in maintenance hemodialysis (MHD) patients and the relationship between CAC and bone metabolism markers and to attempt to find a reliable marker linking vascular calcification and bone metabolism in MHD patients.MethodsA total of 123 patients were enrolled. CAC was assessed by multislice spiral computed tomography (MSCT), and the CAC score (CACS) was evaluated using the Agaston method. Routine laboratory parameters, including triglycerides (TG), total cholesterol (TC), glucose (Glu), calcium (Ca), phosphorus (P), magnesium (Mg), etc., were measured. Serum markers of bone metabolism, such as alkaline phosphatase(ALP), calcitonin (CT), 25-hydroxy vitamin D [25-(OH)D], intact parathyroid hormone (iPTH), total type I procollagen amino-terminal peptide (tPINP), N-terminal mid-fragment of osteocalcin (N-MID OC), and β-type I collagen crosslinked carboxyl-terminal peptide (β-CTX), were also measured.ResultsAmong 123 MHD patients, 37 patients (30.08%) did not have CAC, and 86 patients (69.92%) had CAC, including 41 patients (47.67%) with mild calcification and 45 patients (52.33%) with moderate to severe calcification. Age, Body Mass Index(BMI), the prevalence of hypertension and diabetes mellitus, TC, Glu, P, and Ca×P in the calcification group were higher than those in the noncalcification group, whereas Mg, iPTH, tPINP, N-MID OC, and β-CTX were lower than those in the noncalcified group (P < 0.05). Compared with the mild calcification group (0<CACS<400), P and Ca×P levels were higher in the moderate to severe calcification group (CACS ≥ 400), and ALP, iPTH, N-MID OC, tPINP, and β-CTX concentrations were lower (P < 0.05). Correlation analysis showed that the CACS was positively correlated with TC, LDL-C, P, and Ca×P (P < 0.05) and negatively correlated with N-MID OC and β-CTX (P < 0.05). There was no significant correlation between the CACS and other parameters (P > 0.05). A logistic regression model was used to evaluate the influencing factors for CAC. The results showed that age, BMI, TC, Glu, P, and Ca×P were risk factors for CAC and its severity in MHD patients, whereas diabetes mellitus, Mg, and N-MID OC were protective factors for CAC in MHD patients. In addition, N-MID OC was a protective factor for the severity of CAC. After adjusting for the corresponding confounding factors, the results of the risk factors were consistent, and N-MID OC was still an independent protective factor for CAC and its severity.ConclusionsElevated serum P and Ca×P were independent risk factors for CAC in MHD patients, and serum Mg may be an independent protective factor for CAC. CAC was closely related to abnormal bone metabolism and bone metabolic markers in MHD patients. Relatively low bone turnover can promote the occurrence and development of CAC. N-MID OC may be a reliable bone metabolic marker linking vascular calcification and bone metabolism in MHD patients.

Non‐Fossil Origin Explains the Large Seasonal Variation of Highly Processed Organic Aerosol in the Northeastern Tibetan Plateau (3,200 m a.s.l.)

AbstractCarbonaceous aerosol plays an important role in climate, but its sources and atmospheric processes are least understood in the Tibetan Plateau (TP), a remote yet climatically sensitive region. This study presents the first seasonal cycle of radiocarbon and stable isotope 13C of organic and elemental carbon (OC and EC) in the atmosphere of the northeastern TP. Large seasonal variations of EC and OC concentrations were explained by non‐fossil sources. Regardless of the season, fossil contribution to OC was strongly correlated with inverse OC concentrations. This allowed the separating a constant background source and a source responsible for OC variability that was mostly of non‐fossil origin. The 13C signature of OC shows that OC was highly atmospherically processed and thus less volatile than OC found near sources or in urban areas. The 13C‐depleted secondary sources contributed strongly to more volatile OC, whereas the 13C‐enriched less volatile OC suggests the influence of atmospheric aging.

Human health risk assessment of trace elements in PM10 for industrial areas in Gujarat

Introduction: The present study examines human exposure to Particulate Matter (PM10) and analyses potential health concerns in the industrial zones of Ankleshwar and Vapi in Gujarat.&#x0D; Materials and methods: For Ankleshwar and Vapi, 120 samples were collected, and characterisation was carried out to determine the concentration of NO3, SO4, NH3, K-S, Na, EC, OC, Al, Si, Fe, K, Ti, Ni, Br, Ca, Cl, Mn, Pb, Cr, Zn, S, V, and Cu in PM10 mass. The health risk from exposure to different trace elements, including both carcinogenic and non-carcinogenic, is evaluated for three distinct paths of ingestion, inhalation, and skin contact.&#x0D; Results: The Excess Cancer Risk (ECR) values for Cr and Pb for the ingestion pathway and the carcinogenic risks for Cr, Ni, and Pb for the inhalation pathway are both found to be higher than the minimal permissible threshold (1×10−6) for both children and adults for Ankleshwar and Vapi. However, for Ankleshwar and Vapi, the carcinogenic risks from dermal exposure to Cr and Pb are found to be lower than the permissible limit for both adults and children. It is observed that non-carcinogenic Hazard Index (HI) values for the skin contact and ingestion routes are less than 1 for both children and adults for Ankleshwar and Vapi. While the HI value for the inhalation pathway is found to be larger than the tolerable limit of 1 for both adults and children.&#x0D; Conclusion: For the purpose of creating sustainable cities and improving the health of the urban population, this study will provide a fundamental basis and help the governing authorities design mandatory pollution prevention and control methods, restoration plans, and systematic monitoring programmes.

Effect of Clean Heating on Carbonaceous Aerosols in PM2.5 During the Heating Period in Baoding

In order to study the effects of clean heating measures on the concentration and source of carbonaceous aerosols in PM2.5 in Baoding, we collected PM2.5 samples in Baoding during the winter heating periods of 2014 and 2019. The concentrations of OC and EC in the samples were determined by using a DRI Model 2001A thermo-optical carbon analyzer.The results showed that the average values of ρ(OC) and ρ(EC) in the heating period in 2014 were 60.92 μg·m-3 and 18.15 μg·m-3, and the average values of ρ(OC) and ρ(EC) in the heating period in 2019 were 36.63 μg·m-3 and 6.07 μg·m-3. Compared with those in 2014, the concentrations of OC and EC decreased by 39.87% and 66.56%, respectively, in 2019; the decrease in EC was larger than that in OC, and the meteorological conditions in 2019 were more severe than those in 2014, which was not conducive to the spread of pollutants.The correlation analysis and SOC estimation of OC and EC indicated that the correlation R2 of OC and EC in Baoding in 2014 and 2019 were 0.874 and 0.811, respectively, indicating that OC and EC in Baoding had relatively consistent sources. The average values of ρ(SOC) in 2014 and 2019 were 16.59 μg·m-3 and 11.31 μg·m-3, respectively, and the contribution rates to OC were 27.23% and 30.87%, respectively. This showed that in 2019, compared with that in 2014, the primary pollution decreased, but the secondary pollution increased, and the atmospheric oxidation increased.The analysis of the pollution sources of carbonaceous aerosols revealed that in 2014 and 2019 before and after the implementation of clean heating, the carbonaceous aerosols in the atmosphere were mainly from biomass combustion, coal combustion, and vehicle exhaust emissions. However, the contribution from biomass burning and coal burning decreased in 2019 compared to that in 2014. The decrease in OC and EC concentrations was attributed to the control of coal-fired and biomass-fired sources by clean heating. At the same time, the implementation of clean heating measures reduced the contribution of primary emissions to carbonaceous aerosols in PM2.5 in Baoding City.

Brown carbon absorption in the Mediterranean basin from local and long-range transported biomass burning air masses

This study examines the impact of light absorption from biomass burning (BB) brown carbon (BrC) in the Mediterranean basin from local and distant fire incidents during a typical fire season in August 2019 and under severe fire activity in August 2021. The approaches of Saleh et al. (2014) and Wang et al. (2018) are used to describe the BrC absorption within the WRF-Chem model. Focusing on three regions in the Mediterranean (around the islands of Sicily, Malta, and Crete) that are most affected by BB activity, BrC absorption approximates 5 Mm−1 in OC concentrations up to 3 μg m−3 and can approach 15 Mm−1 in extreme conditions (up to 10 μg m−3). When photochemical bleaching is considered, BrC undergoes almost immediate bleaching upon emission due to high levels of OH radical in the Mediterranean atmosphere during summertime, decreasing light absorption between 56% and 75% under both average and extreme BB conditions. Cloud formation is facilitated above the PBL due to moisture increase induced by BrC at the area of fire events, while transported drier and warmer air masses tend to dissipate cloud formation further away from the BB source. The impact of BrC absorption on irradiances is small (up to −6 W m−2 in extreme conditions) and is often overlapped by the absorption from water vapour variations. BrC direct radiative effect (DRE) is estimated at 0.04 W m−2 (∼10% of BC) in average and 0.18 W m−2 in extreme BB activity under clear sky. Under all sky, low-level clouds dissipation in 2019 with average BB emissions enhances DRE (at 0.15 W m−2), while the higher clouds dissipation in 2021 limits DRE (at 0.11 W m−2) resulting in lower DRE despite the extreme BB conditions.

The impact of seasonality and meteorological conditions on PM2.5 carbonaceous fractions coupled with carbon isotope analysis: Advantages, weaknesses and interpretation pitfalls

PM2.5 samples were collected from October 2020 to September 2021 in Legnica in the Lower Silesia Voivodeship (SW Poland), where environmental guidelines are often exceeded. In order to have a better insight into the respective inputs of local and regional sources concentrations of PM2.5, carbonaceous fractions (TC/OC/EC), carbon isotope composition (δ13CTC) and FTIR spectra of PM2.5 were studied in parallel. The objectives of this study were to (i) identify the emission sources controlling the local aerosol budget and to (ii) discuss the potential limits of the approach used. We highlighted a seasonality in the concentrations of PM2.5, TC, OC, and EC, with higher concentrations in winter resulting of an increased activity of local emission sources coupled to the occurrence of specific meteorological conditions. While we identified coal burning as the main source of pollution in winter, a mix of emissions from coal and bio/organic combustion and road traffic explains the pollution levels in summer. Coupling these findings with the study of FTIR spectra, we corroborated that incomplete combustion of fossil fuels is a major source in winter whereas biogenic particles are in summer. Despite the observed seasonal variations in the OC and EC concentrations, the OC/EC ratios did not show significant variations. It suggests that this ratio, if used as a single proxy to infer sources of carbonaceous aerosols, may lead to interpretation pitfalls. Our results strongly suggest that a multi-proxy approach that couples TC/OC/EC and FTIR to carbon isotope geochemistry provides a reliable evaluation tool for air quality and brings strong constraints on the corresponding sources of PM2.5.

Long-term tillage and cropping systems affect soil organic carbon components and mineralization in aggregates in semiarid regions

Examining soil organic carbon (SOC) mineralization and sequestration under different agricultural practices is pertinent to mitigate climate change and improve soil quality. Soil structure and SOC chemical components are important regulating factors for SOC dynamics. A 12-year field experiment was conducted in Northwest China to assess the effects of cropping system (wheatmaize rotation system and continuous wheat system) and tillage practice (no-tillage, subsoiling and plowing) on SOC stocks, soil aggregate stability, aggregate-associated OC concentrations, chemical components and mineralization. Results showed that wheatmaize rotation, no-tillage and subsoiling increased input-C from crop residue, thus increasing SOC, soil aggregate stability and aggregate-associated OC concentrations. The wheatmaize rotation system with subsoiling had the highest MWD at the 0–40 cm depths as well as increased SOC stock. Fourier transform infrared spectra showed that the OC hydrophobicity within aggregate classes was decreased by wheatmaize rotation system, but increased by no-tillage and subsoiling. Soil aggregates and SOC components jointly affected carbon mineralization kinetics, and the increase in MWD and OC hydrophobicity inhibited OC mineralization. The wheatmaize rotation system increased total carbon mineralization, OC mineralizability and the mineralization rate, which was related to lower OC hydrophobicity. The higher MWD and OC hydrophobicity under no-tillage and subsoiling contributed to decrease SOC mineralizability and delay the carbon mineralization rate (especially slow carbon). At the 0–20 cm depth, no-tillage and subsoiling decreased total carbon mineralization by 21% and 19% compared to plowing, respectively. Overall, the adoption of subsoiling under a wheatmaize rotation system is a promising practice to improve soil structure and SOC sequestration as well as decrease SOC mineralization in semiarid regions.

Effect of Long Term Storage of Soil Sample on Some Chemical Properties of Vertisol and Andosol at Kulumsa Agricultural Sub Centers

The present study was conducted at the Kulumsa Soil and Plant Analysis Laboratory, Ethiopia from January 2021 to January 2022 to identify the appropriate storage duration of soil samples and recommend good storage materials for soil laboratories. The effects of soil sample storage on the pH, TN (%), OC (%), and available phosphorus were studied for 12 months. The highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus at the Kulumsa site were: 6.29 and 5.82; 0.17 and 0.12%; 2.93 and 1.70%; 22.53 and 10.88 respectively. At the Arsi Robe site, the highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus were 6.54 and 5.97, 0.16 and 0.12%, 3.02 and 1.00%, and 19.09 and 10.39 respectively. The highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus (mg kg1) at the Dera site were 9.14 and 8.47; 0.11, 0.07%; 4.36, 1.04%; and 111.85 and 75.37 respectively. Soil samples were stored in three storage containers with replications. The storage materials a card box with a plastic bag and a polyethylene bottle have not made any significant difference in the results of a soil sample stored under laboratory. A card box with a plastic bag was the appropriate material for soil sample storage for long-term analysis. However, based on the cost effectiveness and availability of the material to be purchased for the soil storage condition, the polyethylene plastic bag was the best option for soil sample storage under laboratory conditions.

Effects of land use/land cover changes on soil properties in Rib watershed, Ethiopia

Conversion of natural vegetation into farm land and grazing land causes soil quality loss. Soil properties response to land use/land cover changes (LULC) shows both spatial and temporal variations. This study was aimed at assessing the effects of LULC changes on physical and chemical properties of soil in Rib watershed. To assess physical and chemical properties of the soil among LULC, soil samples were taken over natural forest, grazing and cultivated lands in two agro-ecological belts of Dega and High Dega. Multivariate analysis of variance (MANOVA) and Pearson’s correlation were computed. The study revealed that LULC and agro-ecology have affected physical and chemical properties of the soil in the study watershed. Significant difference in distribution of soil texture, BD, OC, TN and pH among LULC were observed. Soils of Natural forest had higher OC, OC stock and TN. For instance, soils of natural forest had higher OC stock (188.32 Mg/ha) as compared to soils of cultivated lands(72.75 Mg/ha). Soil pH was slightly higher in natural forests and lower in the soils of grazing and cultivated lands. Significant difference (P < 0.05) among the two agro-ecologies were also observed in OC, Ca2+, and contents of clay and silt. In general, LULC change has affected the concentration of TN, OC, pH and BD which in turn can affect soil productivity. Therefore, the study suggests the implementation of an integrated soil fertility management practices and conservation based production systems with the collaboration of regional, local authority and farming community.

Size Distribution of Chemical Components of Particulate Matter in Lhasa

To explore the contributions of chemical components in the particulate matter in Lhasa, the size distribution characteristics of the chemical components, such as carbonaceous species (organic carbon, OC; elemental carbon, EC), water-soluble ions (NH4+, Cl−, SO42−, and NO3−) and trace elements (Na, Ca, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, K, Mg, and Pb), were investigated from August 2018 to May 2019. Principal component analysis (PCA) was also used to simulate the source of the particulate matter. The chemical components showed bimodal size distributions, except for Cu. The highest mass concentration of OC appeared at &lt; 0.49 μm, and the second highest one existed at 1.5–3.0 μm in winter or at 3.0–7.2 μm in other seasons. The maximum concentrations of NH4+, Cl−, SO42−, and NO3− were at &lt; 0.49 μm and peaked at 0.95–1.5 μm or &gt; 3.0 μm. For seasonality, the concentrations of NO3− and SO42− were considerably higher in summer and autumn; trace elements (except for Cu, Zn, V, and Ni), OC, and EC presented higher values during late autumn and winter. The ratio between OC and EC (4.15–33.80) indicated the existence of secondary pollution in Lhasa. The [NO3−]–[SO42−] ratios during summer and autumn exceeding 1 suggested that the currently predominant vehicle exhaust made a greater contribution to the aerosols. According to the results of a PCA, the main pollution sources of particulate matter in Lhasa were suspended dust, biomass burning, fossil fuel combustion, secondary pollution, and vehicular emissions.

Elucidating pollution characteristics, temporal variation and source origins of carbonaceous species in Xinxiang, a heavily polluted city in North China

In order to understand temporal variations, sources origins of carbonaceous components in Xinxiang, an industry city in North China, high time resolution of OC and EC were observed from March 2021 to February 2022. The results illustrated annual average OC and EC concentrations were 5.76 ± 3.65 and 0.83 ± 0.56 μg m−3, respectively. Obvious seasonal and monthly fluctuations of carbonaceous components were observed with high values in cold seasons and low levels in warm seasons. Meanwhile, diurnal variation patterns of carbonaceous species illustrated temporal evolution of boundary layer height (BLH) and variation in emission intensity strongly affected carbonaceous component levels. In addition, obvious correlations between OC and EC (p < 0.001) were found with higher correlation coefficient in autumn, demonstrating they were be likely to originate from similar sources or POC contributed more to OC. The minimum R squared (MRS) method was adopted to calculate second organic carbon (SOC) concentration, represented 52%, 53%, 33%, and 52% of OC in spring, summer, autumn, and winter, respectively. Moreover, two different formation pathways (photochemical oxidation and heterogeneous reactions) of SOC were found in diverse seasons. Furthermore, nonparametric wind regression (NWR) method and potential source contribution function (PSCF) showed the sources from southeast, southwest, and northwest areas were considered as important contributors of carbonaceous species in Xinxiang. This work elucidates the significance of strict control precursors of carbonaceous components and the pressing requirements for coordinated inter−regional prevention and control of air pollution for further improving air quality.

Synthesis of Hydrosiapatite from Muscle Shell Waste Using The Precipitation Method

Hydroxyapatite is a calcium phosphate compound that is the main inorganic component of bones andteeth. Hydroxyapatite has a main role in the medical world because of its identical chemical propertiesand structure to human bone. Kupang shells have a high CaCO3 content of 95-99% by weight. So thisconcurrence, the mussel shells are to be used as good as an ingredient for making Hydroxyapatite. Thevariables used in this research are Temperature of the Furnace and Phosphoric Acid Concentration,which were 700ºC, 750 ºC, 800 ºC, 850 ºC, 900 ºC and Phosphate Acid Concentrations 0.4M, 0.6M,0.8M, 1M, and 1.2M. The product results were tested with XRD analysis to determine the crystalstructure contained in the product and the level of Hydroxyapatite in the product. The best researchresults in this study at a temperature of 900ºC at a concentration of 1.2M phosphoric acid with aHydroxyapatite content of 100% with lattice parameters an (Aº)=b (Aº) = 9..422, c (Aº)=6.8835, andgamma = 120º.

Nonnegligible biogenic organic aerosol and the correlations with light absorption at three high altitude locations in the Qinghai–Tibetan Plateau

To investigate the contribution of primary biological aerosol particles (PBAPs) to aerosol and the correlations with brown carbon (BrC) light absorption over the Tibetan Plateau (TP), the total suspended particle (TSP) samples were collected at three high altitude sites. The spatial variations of PBAPs tracers and absorption Ångström exponent (AAE) were obtained over the TP for the first time. Elevated PBAPs tracers concentrations were observed in the northeastern and southwestern sites compared to the central TP. The high concentrations of FSPD OC (the fungal-spore-derived OC and plant-debris OC) and PBAPs were obtained in the northeastern (with 74 ng m−3 and 2333 ng m−3) and southwestern sites (with 80 ng m−3 and 2682 ng m−3), respectively. The results indicated that PBAPs may be important fraction of BrC chromophores in the southwestern TP. The highest AAEs of BrC, primary BrC (BrCpri), and secondary BrC (BrCsec) were observed in the northeastern site with the values of 5.1, 3.7, and 5.7, respectively. The potential PBAPs and FSPD OC source distributions were obtained. The results are important for evaluating the effects of PBAPs in the TP.

Investigation of organic carbon profiles and sources of coarse PM in Los Angeles

Source apportionment analyses are essential tools to determine sources of ambient coarse particles (2.5 <dp < 10 μm) and to disentangle their association and contribution from other pollutants, particularly PM2.5 (<2.5 μm). A semi-continuous sampling campaign was conducted using two virtual impactors/concentrators to enhance coarse particulate matter concentrations coupled with an online thermal-optical EC/OC monitor to quantify coarse PM–bound organic carbon volatility fractions (OC1-OC4) in central Los Angeles during the winter, spring, and summer of 2021. The total OC and its volatility fraction concentrations, meteorological parameters (i.e., wind speeds and relative humidity), vehicle miles traveled (VMT), and gaseous source tracers (i.e., O3 and NO2) were used as inputs to positive matrix factorization (PMF) model. A 3-factor solution identified vehicular emissions (accounting for 46% in the cold phase and 26% in the warm phase of total coarse OC concentrations), secondary organic carbon (27% and 37%), and re-suspended dust (27% and 37%) as the primary organic carbon sources of coarse PM. The re-suspended dust factor showed a higher contribution of more volatile organic carbons (i.e., OC1 up to 77%) due to their re-distribution on dust particles, whereas the SOA factor was the dominant contributor to less volatile organic aerosols (i.e., OC4 up to 54%), which are the product of reactions at high relative humidity (RH). Our findings revealed that the total OC concentrations in the coarse size range were comparable with those of previous studies in the area, underscoring the challenges in curtailing coarse PM-bound OC sources and the necessity of developing effective emission control regulations on coarse PM. The results from the current study provide insights into the seasonal and temporal variation of total OC and its volatility fractions in Los Angeles.

Heterogeneous changes of chemical compositions, sources and health risks of PM2.5 with the “Clean Heating” policy at urban/suburban/industrial sites

China has enacted the “Clean Heating” (CH) policy in north China. The domain-specific impacts on PM2.5 constituents and sources in small cities are still lacking, which obstruct the further policy optimization. Here, we performed an intensive observation covering the heating period (HP) and pre-heating period (PHP) in winter of 2017 at urban (UR), industrial (IS), and suburban (SUR) sites in one of the “2 + 26” cities. The mean PM2.5 concentrations at UR and IS decreased by 15.2 % and 4.6 %, while increased by 9.8 % at SUR in the HP compared with the PHP, indicating the heterogeneous responses. The lowest contribution percentages of coal combustion (14.6 %) and industrial emissions (17.1 %) to PM2.5 at UR in the HP implied the CH policy played more effective role. The most increase in NO3−/SO42− ratio by 26.8 % and the highest NO3− concentration at UR in the HP were linked mainly with the thermal-NOx emitted from natural gas (NG) burning in view of NOx emission reductions from other sources. The highest concentrations of OC, SO42−, K+, and Cl−, and contribution percentages of biomass burning (20.0 %) and coal combustion (24.8 %) to PM2.5 at SUR in the HP evidenced the enhanced usage of biomass/coal. Coal banning in the HP at IS and UR led to the obvious decreases in OC, SO42−, As, and Sb. Secondary nitrate became the largest PM2.5 source at IS and UR in the HP. Coal banning, emission control on large-size enterprises and ignored control on small-size enterprises efficiently modified the concentrations and health risks of heavy metals. The lowest carcinogenic risks moved from SUR in the PHP to UR in the HP. The policies on de-NOx of NG-burning related enterprises, reduction of biomass/coal usage in suburban area, and strict regulation of small-size enterprises were urgently need to further improve the air quality.