Resin Acids Research Articles

Wear of the 3D Printed Polylactic Acid Elements Sliding against the Synthetic Resins at the Higher Speed Friction

Since the requirement of high dust-free levels, it is necessary to develop the technologies with anti-wear and low dust generation for drive elements that can be quickly printed. Polylactic acid and synthetic resins are often paired with each other for the 3D printed driven elements. To achieve "smooth friction", the adhesion wear under dry friction conditions should be reduced. To achieve a "high dust-free level", the anti-wear of the paired elements under higher speed friction should be improved to reduce the generation of abrasive dust. Therefore, wear of the 3D printed polylactic acid elements sliding against the synthetic resins at the high speed friction are investigated in this paper.

Contents of an Early Byzantine Amphora from Kruglaya Bay, the Black Sea

A fragment of an amphora found in the Kruglaya Bay near Sevastopol was filled with an unknown brown substance with a strong smell of tar. On the vessel’s neck, there is a round stamp ~30 mm in diameter, depicting the bust of an emperor encircled by an inscription. It resembles stamps on amphorae made in Alexandria and the Geronisos Island. The inscription reads, “επί Πτολεμαίου επάρχου”. The gas chromatography–mass spectrometry analysis revealed dehydroabietic acid, methyl dehydroabietate, norabietatrienes, retene, and other phenanthrene derivatives, suggesting that the substance resulted from dry distillation of wood of the Pinaceae family. The headspace analysis yielded components of turpentine oil such as α-pinene, camphene, limonene, cymenes, and others terpenes. To establish the sample’s origin, the amphora’s content was compared with modern pinewood tar obtained by the traditional method. Given nearly identical chromatogram profiles of the amphora’s contents and of tar in areas relating to resin acids, similar values of peak areas of biomarker components, and the presence of turpentine oil components in the sample, it is highly probable that the amphora indeed contained tar.

Investigation of the Effect of Chemical Treatment on the Properties of Colombian Banana and Coir Fibers and Their Adhesion Behavior on Polylactic Acid and Unsaturated Polyester Matrices

In this work, the adhesion behavior of chemically treated banana and coir Colombian fibers embedded in polylactic acid (PLA) and unsaturated polyester resin (UPR) matrices was investigated. Both types of fibers were treated with a 5 wt.% sodium hydroxide solution for one hour. The properties of treated and untreated fibers were determined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and tensile tests. To evaluate the adhesion behavior of the fibers in PLA and UPR matrices, pull-out tests were performed, and the percentage of broken fibers was determined. The results showed that alkaline treatment improved the fibers’ physicochemical, mechanical, and thermal properties. In addition, the alkaline treatment was able to improve the adhesion behavior of coir and banana fibers to PLA and UPR matrices. The banana fibers showed a percentage of broken fibers of 100%, while the coir fibers showed a slight increase in IFSS value. This behavior is attributed to the improvement in surface roughness due to the removal of non-cellulosic composites and impurities.

Key Materials in Solder Mask Ink for Printed Circuit Board

AbstractSolder mask ink (SMI) layer can avoid the short circuit between electronic component and land for the fabrication of printed circuit board (PCB). More importantly, the layer not only protects the board from the corrosion of moisture, mildew, or salt spray but also reduces the contamination of weld, and increases the degree of insulation by forming stable three‐dimensional net structure. Therefore, the SMI plays a decisive role for the service life of PCB. This review mainly summarizes three types of SMI including epoxy resin ink, acrylic acid resin ink, and phenolic resin ink for PCB. The focus is the effect of the changes of key materials, such as the design of the binder resin, the selection of the curable agent, and the variation of the colorant and initiator on the performances of epoxy resin SMI layer. Then other types of ink such as acrylic acid resin ink and phenolic resin ink have been discussed, especially about how the change of the binder resin influences the SMI film properties. At last, the development trend of the SMI is proposed. The review has significant meaning for the development and improvement of the SMI and the investigation is important for the application and exploitability of the high‐quality PCBs.

Making wood inspection easier: FTIR spectroscopy and machine learning for Brazilian native commercial wood species identification.

The molecular structure of wood is mainly based on cellulose, lignin, and hemicellulose. However, low concentrations of lipids, phenolic compounds, terpenoids, fatty acids, resin acids, and waxes can also be found. In general, their color, smell, texture, quantity, and distribution of pores are used in human sensory analysis to identify native wood species, which may lead to erroneous classification, impairing quality control and inspection of commercialized wood. This study developed a fast and accurate method to discriminate Brazilian native commercial wood species using Fourier Transform Infrared Spectroscopy (FTIR) and machine learning algorithms. It not only solves the limitations of traditional methods but also goes beyond as it allows fast analyses to be obtained at low cost and high accuracy. In this work, we provide the identification of five Brazilian native wood species: Angelim-pedra (Hymenolobium petraeum Ducke), Cambara (Gochnatia polymorpha), Cedrinho (Erisma uncinatum), Champagne (Dipteryx odorata), and Peroba do Norte (Goupia glabra Aubl). The results showed the great potential of FTIR and multivariate analysis for wood sample classification; here, the Linear SVM differentiated the five wood species with an accuracy of 98%. The developed method allows industries, laboratories, companies, and control bodies to identify the nature of the wood product after being extracted and semi-manufactured.

Removal of boron from wastewaters using valonia-tannin-based biosorbent produced via spray drying

The primary objective of this study is to assess the adsorption behavior of boron using a tannin-based biosorbent known as tannic acid resin, synthesized from Turkish acorns (valonia) through the spray-drying method. The resulting biosorbent, named Valex, underwent modification into a tannic acid resin-based structure, rendering it suitable for use as a biosorbent. Comprehensive characterization studies involving Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller analysis were conducted on this biosorbent. The outcomes demonstrated the effectiveness of tannic acid resin, a tannin-based biosorbent, in removing boron from aqueous solutions. Various parameters such as pH, initial boron concentration, and adsorbent dosage were investigated for their impact on boron removal. The study also delved into adsorption kinetics, adsorption isotherm models, and adsorption thermodynamics. Maximum boron removal, reaching 92.9%, was achieved using 1 g of tannic acid resin-based biosorbent with an initial boron concentration of 8 mg L−1 within 6 h at pH 3. The Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models were applied to experimental data, with the Temkin model demonstrating a good fit. Adsorption kinetics were explored using pseudo-first-order, pseudo-second-order, Elovich, first-order, second-order, and intraparticle diffusion models, with the pseudo-second-order kinetic model fitting the data effectively. The negative values of Δ G° at all temperatures indicated the spontaneous nature of boron adsorption on the tannin resin, and the positive value of Δ H° suggested the endothermic nature of adsorption. This study shows the efficacy of Valex in boron adsorption and suggests its potential application as an effective method for boron removal. This study's findings on the impact of various parameters on boron removal provide insights for optimizing the boron adsorption process in practical applications.

Isolation of Polyphenols from Aqueous Extract of the Halophyte Salicornia ramosissima.

Polyphenols from residual non-food grade Salicornia ramosissima have health-promoting effects in feed, food, or nutraceutical applications. Therefore, the isolation of polyphenols is of interest from a series of environmentally friendly isolation methods with recyclable solvents. The isolation of polyphenols from non-food grade S. ramosissima was investigated using sequential membrane filtration with and without acid pretreatment, liquid-liquid extraction, resin adsorption, and centrifugal partition chromatography (CPC); analyzed by the Folin-Ciocalteu assay for total polyphenols; and finally analyzed using UPLC-TQMS in negative ion-spray mode for detection of 14 polyphenols. Sequential membrane filtration and acid hydrolysis indicated the polyphenols forming complexes with other compounds, retaining the polyphenols in the retentate fraction of large molecular weight cut-off membrane sizes. Conventional liquid-liquid extraction using sequential ethyl acetate and n-butanol showed most polyphenols were extracted, apart from chlorogenic acids, indicating a low isolation efficiency of higher polarity polyphenols. Analysis of the extract after resin adsorption by Amberlite XAD-4 resin showed high efficiency for separation, with 100% of polyphenols adsorbed to the resin after 13 bed volumes and 96.7% eluted from the resin using ethanol. CPC fractionations were performed to fractionate the concentrated extract after resin adsorption. CPC fractionations of the 14 polyphenols were performed using an organic or aqueous phase as a mobile phase. Depending on the mobile phase, different compounds were isolated in a high concentration. Using these easily scalable methods, it was possible to comprehensively study the polyphenols of interest from S. ramosissima and their isolation mechanics. This study will potentially lead the way for the large-scale isolation of polyphenols from S. ramosissima and other complex halophytes. The compounds of the highest concentration after CPC fractionation were isoquercitrin and hyperoside (155.27 mg/g), chlorogenic acid (85.54 mg/g), cryptochlorogenic acid (101.50 mg/g), and protocatechuic acid (398.67 mg/g), and further isolation using CPC could potentially yield novel polyphenol nutraceuticals.

COLOPHONY and It’s Derivatives as Corrosion Inhibitor Agent

Colophony obtained from oleoresin, toll oil and wood stump sources from the Pine species. The dominant components of colophony are resin acids and abietic acid forms the primary resin acid. Colophony and derivatives as inhibitor agent of metallic surface corrosion and alloy dissolution in corrosive environments reviewed. The novel approach and basic chemical reactions of the colophony derivatives as a corrosion inhibitor given in detailed. Toxicity research approved that colophony and derivatives practically non-toxic component. This evidence has strengthened the reason why colophony is the escalated attention of industrial applications. 
 Colophony is considered green oil because it is renewable, inexpensive, and environmentally friendly material. The ability of colophony, also named naval store, to improve the sealing properties of ships is well known feature. In the oil industry, colophony derivatives have rising interest of corrosion inhibitors thanks to their amphiphilic nature. Additionally, it could be utilized as petroleum dispersants. Colophony derivatives are renewable raw material which has enhanced solubility and ambient in nature. Besides, comparing to petroleum-based materials it has affordable price and low toxicity. Therefore, colophony and derivatives have advantageous as a unique raw material of advanced polymers applications compared to chemical based toxic corrosion inhibitors. A critical note that colophony and derivative does not causing water pollution in field such as maritime transportation.

Extraction and isolation of hydrophobic compounds and tannins from Pinus radiata bark using switchable hydrophilicity solvents

Pinus radiata is the dominant species of tree in the New Zealand forestry industry, with 38.3 million m3 of P. radiata trees harvested annually. Bark is removed from these trees when they are processed into logs, resulting in bark waste that is currently burnt to provide energy and heat or used as garden mulch despite its potential as a source of biorenewable chemicals such as waxes and polyphenols. To date, work to extract and isolate these components as part of a bark biorefinery has been affected by extraction selectivity and the energy efficiency of the extraction and isolation procedure, particularly the need to distill the solvent to recover the extract. Switchable hydrophilicity solvents N,N-dimethylcyclohexylamine (DMCHA) and N-methylcyclohexylamine (MCHA) have been explored for the extraction of hydrophobic compounds and tannins from P. radiata bark to enable the near ambient temperature recovery and isolation of these fractions. Fatty acids and alcohols were extracted by DMCHA and MCHA in their hydrophobic form and recovered by switching their polarity using CO2 and water in yields ranging from 1.1 – 4.5% relative to bark mass under optimised conditions. Compared with the use of supercritical CO2 extractions, DMCHA and MCHA showed greater selectivity toward fatty acids compared with resin acids. In their hydrophilic form, DMCHA showed greater selectivity than MCHA towards the extraction and separation of tannins compared with lignin and carbohydrates. Tannins were recovered with DMCHA by the reversible switching process in yields of 18% relative to total bark mass under optimised conditions compared with 5% for MCHA. The ability to recycle the solvents was demonstrated, with consistent results observed for DMCHA.

Improving the properties of polylactic acid/polypropylene carbonate blends through cardanol-induced compatibility enhancement

Cardanol (CD) is used as a reactive compatibilizer, and blended with polylactic acid (PLA) and polypropylene carbonate (PPC) resin (70/30(w/w)) to obtain a series of PLA/PPC/CD blends. The systematic study was conducted on the thermal properties, optical properties, rheological properties, mechanical properties, and microscopic morphology of the blend, by varying amounts of CD added to the blends. A detailed explanation and comprehensive analysis of the reaction mechanism between CD and PLA/PPC have been made. The study found that CD acts as a “bridge” between the PLA and PPC, forming the structure of a block copolymer (PLA-b-CD-b-PPC), and the copolymer can greatly improve the compatibility of PLA and PPC. When the amount of CD reaches 8 wt%, only one Tg is observed in the blend, simultaneously, PLA/PPC has already transitioned from a partially compatible system to a completely compatible system. At the same time, the addition of CD does not have any negative impact on the thermal stability of the PLA/PPC blend under processing temperature conditions, and the thermal stability of the PLA/PPC/CD blends can even be improved under extreme conditions. In addition, the addition of CD allows the PLA/PPC/CD blends to maintain a high light transmittance while reducing the opacity of the blend (the light transmittance remains above 92 %, and the opacity is reduced from 37 % to about 24 %), demonstrating excellent optical properties. Moreover, the elongation at break and impact strength of the PLA/PPC/CD blend both show a trend of first increasing and then decreasing with the increase of CD amount. When the CD amount varies within the range of 6– 8 wt%, the blends undergoes a brittle-ductile transition, and its toughness is greatly improved while the rigidity can also meet practical needs. When the amount of CD in the system increases to 12 wt%, the toughness of the blend reaches its peak, and its elongation at break and impact strength reach 513.24 % and 9211.5 J/m2 respectively (increased to 2442.84 % and 270.73 % of the PLA/PPC blend). Concurrently, the fracture surface of the blend exhibits large-scale plastic flow in the direction of the applied force, with marked shear yield phenomena, showing obvious characteristics of tough fracture.

Structured Emulgels by Interfacial Assembly of Terpenes and Nanochitin.

Interfacial assemblies formed by colloidal complexation are effective in multiphase stabilization, as shown in structured liquids and Pickering emulgels. Herein, we demonstrate a type of biobased colloidal system that spontaneously stabilizes an organic phase in a continuous hydrogel phase. Specifically, a triterpene extracted from bark (betulin, BE) is added to an organic phase containing a coniferous resin (rosin acid, a diterpene). BE is shown to take part in strong noncovalent interactions with the nanochitin dispersed in the aqueous (hydrogel) phase, leading to a complex of high interfacial activity. The viscoelastic response of the system is rationalized by the presence of a superstable structured dual network. When used as a templating material, the emulgel develops into structured liquids and cryogels. The herein introduced all-biobased type of nanoparticle surfactant system forms a gel ("emulsion-filled" with "aggregated droplets") that features the functional benefits of both betulin and nanochitin.

Resin acids play key roles in shaping microbial communities during degradation of spruce bark

The bark is the outermost defense of trees against microbial attack, largely thanks to toxicity and prevalence of extractive compounds. Nevertheless, bark decomposes in nature, though by which species and mechanisms remains unknown. Here, we have followed the development of microbial enrichments growing on spruce bark over six months, by monitoring both chemical changes in the material and performing community and metagenomic analyses. Carbohydrate metabolism was unexpectedly limited, and instead a key activity was metabolism of extractives. Resin acid degradation was principally linked to community diversification with specific bacteria revealed to dominate the process. Metagenome-guided isolation facilitated the recovery of the dominant enrichment strain in pure culture, which represents a new species (Pseudomonas abieticivorans sp. nov.), that can grow on resin acids as a sole carbon source. Our results illuminate key stages in degradation of an abundant renewable resource, and how defensive extractive compounds have major roles in shaping microbiomes.

Superhydrophobic coating composed of rosin acid and TiO2 with antimicrobial properties and excellent mechanical durability for oil/water separation

Developing multifunctional materials with green, lasting, and simple preparation processes is a hot topic and challenge in solving the problem of oil spill contamination. A multifunctionalized superhydrophobic coating was generated via cross-linking 3-(Trimethoxysilyl) propyl acrylate with Polyethyleneimine in a multifunctional covalent manner and modifying the cotton fabric surface with silylated modified rosin acid (RA-Si) as well as TiO2 nanoparticles. The coated samples had remarkable superhydrophobicity with self-cleaning as well as stain resistance. With bactericidal rates of 97.73 % and 98.36 %, respectively, the coated samples effectively inhibited the formation of biofilms and showed high antimicrobial performance for both Staphylococcus aureus and Escherichia coli. Meanwhile, the coated samples showed outstanding oil absorption and separation of the oil-water mixture. Both water-in-oil and oil-in-water stable emulsions would be effectively separated out of the coated samples after demulsifying. Additionally, the water droplet contact angle of the coated samples was maintained at approximately 150.0° after mechanical and chemical testing. It was noteworthy that the coated samples still exhibited satisfactory separation for stabilizing oil/water emulsions after mechanical wear and chemical corrosion treatment, indicating their excellent mechanical durability. The prepared multifunctional RA-TiO2 superhydrophobic coating has promising applications in oil-containing wastewater treatment and environmental remediation.

Preparation of graphene oxide/polyiminodiacetic acid resin as a high-performance adsorbent for Cu(II)

Preparation of graphene oxide/polyiminodiacetic acid resin as a high-performance adsorbent for Cu(II)

Adsorption Ability of Nitrogen-Containing Polymer Sorbents Based on Urea-Formaldehyde Resin and Aminoacetic Acid Towards Heavy Metal Ions

Adsorption Ability of Nitrogen-Containing Polymer Sorbents Based on Urea-Formaldehyde Resin and Aminoacetic Acid Towards Heavy Metal Ions

Carbonate Associated Sulfate Extraction Method Using Weakly Acidic Cation Exchange Resins

The sulfur (S) mass fraction of carbonate minerals can be used to reconstruct the environmental conditions and S sources at the time of precipitation. As S is present in a wide range of host materials, there is an urgent need to develop a method to extract S from a single mineral phase. We have developed a method to extract structurally substituted sulfate, termed carbonate‐associated sulfate (CAS), from geological and biogenic carbonate minerals using weakly acidic cation exchange resins. Two types of weakly acidic cation exchange resin (methacrylic acid and acrylic acid types) were tested to minimise the blank S contents and decompose carbonate. After repeated cleaning of the resins with high‐purity water or HCl, the blank S contents were reduced to < 0.1 μg, which is < 0.1% of the CAS in the samples. The cleaned resin was used to dissolve 10 and 25 mg of the JCp‐1 carbonate certified reference material (CRM; Japanese National Institute of Advanced Industrial Science and Technology, AIST). Samples and resin were added to 8 ml of high‐purity water at resin/sample ratios of 2, 5, 10 and 20, set on a shaking table, and reacted. The supernatant solutions were sampled sequentially from 0.5 h to 87 h after the start of experiments. The results show that the optimal conditions for decomposing 10 mg of carbonate is a resin/sample ratio of ≥ 10 with a reaction time of ≥ 40 h. Carbonate‐associated S mass fractions were measured for six geological and biogenic carbonate CRMs. The coefficient of variation in carbonate‐associated S mass fractions was ≤ 7%, regardless of the type of resins used. The mass fractions determined with this method recover 74–94% of the total S mass fractions reported in previous studies, suggesting that this method dissolved carbonate, and did not leach other S‐bearing fractions that are not resistant to weak acids. Another benefit of this method is that the decomposed solution can be introduced directly into the ion chromatograph, allowing for more sensitive analyses. We emphasise that this method can also be used for S isotopic measurements, as S contamination from other S‐bearing mineral phases is low.

Bulk and molecular-level composition of primary organic aerosol from wood, straw, cow dung, and plastic burning

Abstract. During the past decades, the source apportionment of organic aerosol (OA) in ambient air has been improving substantially. The database of source retrieval model-resolved mass spectral profiles for different sources has been built with the aerosol mass spectrometer (AMS). However, distinguishing similar sources (such as wildfires and residential wood burning) remains challenging, as the hard ionization of the AMS mostly fragments compounds and therefore cannot capture detailed molecular information. Recent mass spectrometer technologies of soft ionization and high mass resolution have allowed for aerosol characterization at the molecular formula level. In this study, we systematically estimated the emission factors and characterized the primary OA (POA) chemical composition with the AMS and the extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) for the first time from a variety of solid fuels, including beech logs, spruce and pine logs, spruce and pine branches and needles, straw, cow dung, and plastic bags. The emission factors of organic matter estimated by the AMS and hydrocarbon gases estimated by the total hydrocarbon analyzer are 16.2 ± 10.8 g kg−1 and 30.3 ± 8.5 g kg−1 for cow dung burning, which is generally higher than that of wood (beech, spruce, and pine), straw, and plastic bag burning (in the range from 1.1 to 6.2 g kg−1 and 14.1 to 19.3 g kg−1). The POA measured by the AMS shows that the f60 (mass fraction of m/z 60) varies from 0.003 to 0.04 based on fuel types and combustion efficiency for wood (beech, spruce, and pine) and cow dung burning. On a molecular level, the dominant compound of POA from wood, straw, and cow dung is C6H10O5 (mainly levoglucosan), contributing ∼ 7 % to ∼ 30 % of the total intensity, followed by C8H12O6 with fractions of ∼ 2 % to ∼ 9 %. However, as they are prevalent in all burning of biomass material, they cannot act as tracers for the specific sources. By using the Mann–Whitney U test among the studied fuels, we find specific potential new markers for these fuels from the measurement of the AMS and EESI-TOF. Markers from spruce and pine burning are likely related to resin acids (e.g., compounds with 20–21 carbon atoms). The product from the pyrolysis of hardwood lignins is found especially in beech log burning. Nitrogen-containing species are selected markers primarily for cow dung open burning. These markers in the future will provide support for the source apportionment.

Catalyst-free epoxy vitrimers from rosin: Highly mechanical performance, fast self-healing, and facile recycling

Recyclable epoxy vitrimers from biomass are significant for sustainable industrial development. However, the reprocessing of epoxy vitrimers comes at the cost of their mechanical properties and thermal stability and it is a challenge to obtain epoxy vitrimers with facile recycling ability, high mechanical properties and thermal stability, simultaneously. Present work offers a way to prepare the high-performance epoxy vitrimers with dual dynamic β-hydroxy ester bonds and boroxines from rosin derived glycidyl ester epoxy resin and 3-aminobenzeneboronic acid. The presence of tertiary amines and dynamic β-hydroxy ester bonds, as well as dynamic boroxines in the network accounts for the effective malleable behavior without the assistance of a catalyst. The resultant rosin-based epoxy vitrimers possess the Tg around ∼83.2 °C with the Ts above 170 °C, the E′ of 36.1 MPa and the tensile strength around ∼60.9 MPa comparable to commercial BPA epoxies, which attribute to the rigid rosin structure and high crosslink degree. The integrated self-healing of scratches after heating at 120 °C for 30 min is achieved, and the self-healing efficiency in terms of Young’s modulus is 97.8 %. The welding efficiency of tensile strength reaches 94.4 % after welding treatment at 120 °C for 30 min. The reprocessed samples with the first generation obtained from hot press (8 MPa) at 140 °C for 3.5 h exhibit the tensile strength of 54.9 MPa. A close-loop recycling of rosin-based epoxy vitrimers was demonstrated, the retention ratio the recycled sample in terms of tensile strength of 82.6 %. Therefore, the REB networks with unique properties are desired alternatives to commercial epoxy resin and show the potential applications in transportation, aerospace and construction materials.

Design of Cell-Adhesive Shellac Derivatives and Endowment of Photoswitchable Cell-Adhesion Properties.

The emergence of new biodegradable cell-adhesion materials is an attractive topic in biomaterial chemistry, particularly for the development of cell incubation scaffolds and drug encapsulation materials used in in situ regenerative therapy. Shellac is a natural resin with unique film-forming properties and high miscibility with various chemicals, in addition to being biodegradable and nontoxic to biological systems. However, since native shellac does not adhere to mammalian cells, there have been no reports of using shellac to develop cell-adhesive biomaterials. In this study, we report on the development of cell-adhesive shellac derivatives through slight chemical modification. Shellac is a mixture of oligoesters that consists of hydroxyl fatty acids and resin acids, and therefore, all oligomers have one carboxylic acid group at the terminal. We discovered that a simple modification of hydrophobic chemical groups, particularly those containing aromatic groups in the ester form, could dramatically improve cell-adhesion properties for mammalian cells. Furthermore, by using photocleavable esters containing aromatic groups, we successfully endowed photoswitchable properties in cell adhesion. Given that shellac is a low-cost, biodegradable, and nontoxic natural resin, the modified shellacs have the potential to become new and attractive biomaterials applicable to in situ regenerative therapy.

Anthropogenic emission controls organic aerosols at Gosan background site in the outflow from northeast Asia

Anthropogenic activities release substantial amounts of organic components into the atmosphere. In this study, eight groups of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, n-alkanes, fatty acids, fatty alcohols, phthalate esters, and lignin and resin acids were identified in the ambient aerosol samples collected from a regional background site in the Korean Climate Observatory at Gosan (KCOG), South Korea. The total identified organics were most abundant in winter (220 ± 60.3 ng m−3), followed by spring, autumn, and summer, with the predominance of n-fatty acids. All classes of aliphatic lipid components showed a significant positive correlation with fossil fuel-derived organic carbon (OC-FF) and biomass burning-derived organic carbon (OC-BB), indicating that they were abundantly emitted from anthropogenic sources such as fossil fuel combustion and biomass burning. The composition profiles and diagnostic ratios of PAHs indicate that they were largely derived from coal and/or biomass combustion in the continent. In contrast, hopanes are predominantly emitted from gasoline or diesel engines, particularly in the summer, from commercial ships. The high concentration of phthalates in the summer suggested that plastic emissions from the open ocean substantially contributed to the Gosan aerosols. The low ratios of unsaturated/saturated fatty acids indicate that Gosan organic aerosols were photochemically aged during atmospheric transport. The temporal and seasonal variations of organic species over KCOG provide crucial information on the emission strengths of different contributing sources in the East Asian outflow. Positive Matrix Factorization (PMF) results and 14C-based source apportionment studies demonstrated that anthropogenically derived organic aerosols largely contributed to the aerosol mass over KCOG. Thus, the East Asian continent might be the major source region for organic aerosols over the western North Pacific, except in the summer.