Exploring optical descriptors for rapid estimation of coastal sediment organic carbon and nearby land-use classifications via machine learning models.

This study utilizes ultraviolet and fluorescence spectroscopic indices of dissolved organic matter (DOM) from sediments, combined with machine learning (ML) models, to develop an optimized predictive model for estimating sediment total organic carbon (TOC) and identifying adjacent land-use types in coastal sediments from the Yellow and Bohai Seas. Our results indicate that ML models surpass traditional regression techniques in estimating TOC and classifying land-use types. Penalized Least Squares Regression (PLR) and Cubist models show exceptional TOC estimation capabilities, with PLR exhibiting the lowest training error and Cubist achieving a correlation coefficient 0.79. In land-use classification, Support Vector Machines achieved 85.6 % accuracy in training and 92.2 % in testing. Maximum fluorescence intensity and ultraviolet absorbance at 254 nm were crucial factors influencing TOC variations in coastal sediments. This study underscores the efficacy of ML models utilizing DOM optical indices for near real-time estimation of marine sediment TOC and land-use classification.

Integrated assessment of the natural purification capacity of tidal flat for persistent toxic substances and heavy metals in contaminated sediments.

Natural purification of pollutants is highly recognized as regulating ecosystem services; however, the purification capacity of tidal flats remains largely unknown and/or unquantified. A 60-day mesocosm transplant experiment was conducted in situ to assess the purification capacity of natural tidal flats. We adopted the advanced sediment quality triad approach, monitoring 10 endpoints, including chemical reduction, toxicity changes, and community recoveries. The results indicated that contaminated sediments rapidly recovered over time, particularly > 50% within a day, then slowly recovered up to âˆ¼ 70% in a given period (60 days). A significant early reduction of parent pollutants was evidenced across all treatments, primarily due to active bacterial decomposition. Notably, the presence of benthic fauna and vegetated halophytes in the treatments significantly enhanced the purification of pollutants in both efficacy and efficiency. A forecast linear modeling further suggested additive effects of biota on the natural purification of tidal flats, reducing a full recovery time from 500 to 300 days. Overall, the triad approach with machine learning practices successfully demonstrated quantitative insight into the integrated assessment of natural purification.

Phytoplankton assemblage responses to massive freshwater inputs and anthropogenic toxic substances contamination in the Geum River Estuary, South Korea.

This study investigated the relationships between phytoplankton assemblages and water contamination by persistent toxic substances (PTSs) and nutrients in an estuary with an artificial dam over one year. The distribution of PTSs, including 15 polycyclic aromatic hydrocarbons, 6 alkylphenols, and 8 metal(loid)s, along with nutrients, exhibited relatively high concentrations with irregular temporal fluctuations in the inner estuary. During winter and spring, phytoplankton communities showed good ecological quality, with an average of 28 species and a density of 1750 cells L-1. In contrast, during summer, there was a significant increase in the density of freshwater species (max 45,000 cells L-1). These assemblages were categorized into three seasonal groups, featuring dominant taxa like blue-green algae and diatoms. Temperature and nutrient levels were the principal factors influencing phytoplankton assemblages, while PTSs had a minor impact. Overall, phytoplankton assemblages displayed strong seasonal variation, mainly influenced by freshwater input and nutrient availability.

Tenacibaculum tangerinum sp. nov., isolated from a tidal flat sediment.

An orange-coloured bacterium, designated as strain GRR-S3-23T, was isolated from a tidal flat sediment collected from Garorim Bay, Chuncheongbuk-do, Republic of Korea. Cells of GRR-S3-23T were aerobic, Gram-stain-negative, rod-shaped and motile. GRR-S3-23T grew at 18-40 °C (optimum, 30 °C), pH 7.0-9.0 (optimum, pH 7.0) and with 2-4 % NaCl (optimum, 2-3 % w/v). Results of 16S rRNA gene sequence analysis indicated that GRR-S3-23T was closely related to Tenacibaculum aiptasiae a4T (97.6 %), followed by Tenacibaculum aestuarii SMK-4T (97.5 %), Tenacibaculum mesophilum MBIC 1140T (97.4 %), Tenacibaculum singaporense TLL-A2T (97.3 %), Tenacibaculum crassostreae JO-1T (97.2 %),and Tenacibaculum sediminilitoris YKTF-3T (97.1 %). The average amino acid identity values between GRR-S3-23T and the related strains were 86.8-72.8 %, the average nucleotide identity values were 83.3-74.1 %, and the digital DNA-DNA hybridization values were 27.0-19.6 %. GRR-S3-23T possessed menaquinone-6 (MK-6) as major respiratory quinone and had summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c, 20.6 %) and iso-C15 : 1G (10.8 %) as major fatty acids (>10.0 %). The polar lipid profiles of GRR-S3-23T contained phosphatidylethanolamine, one unidentified aminolipid, one unidentified aminophospholipid, three unidentified lipids, one unidentified glycolipid and four unidentified phospholipids. The DNA G+C content of GRR-S3-23T was 33.7%. On the basis of the results of the polyphasic analysis involving phylogenetic, phylogenomic, physiological and chemotaxonomic analyses described in this study, GRR-S3-23T is considered to represent a novel species within the genus Tenacibaculum, for which the name Tenacibaculum tangerinum is proposed. The type strain is GRR-S3-23T (=KCTC 102029T=KACC 23271T=JCM 36353T).

Effect-Directed Analysis Combined with Nontarget Screening to Identify Unmonitored Toxic Substances in the Environment.

Effect-directed analysis (EDA) combined with nontarget screening (NTS) has established a valuable tool for the identification of unmonitored toxic substances in environmental samples. It consists of three main steps: (1) highly potent fraction identification, (2) toxicant candidate selection, and (3) major toxicant identification. Here, we discuss the methodology, current status, limitations, and future challenges of EDA combined with NTS. This method has been applied successfully to various environmental samples, such as sediments, wastewater treatment plant effluents, and biota. We present several case studies and highlight key results. EDA has undergone significant technological advancements in the past 20 years, with the establishment of its key components: target chemical analysis, bioassays, fractionation, NTS, and data processing. However, it has not been incorporated widely into environmental monitoring programs. We provide suggestions for the application of EDA combined with NTS in environmental monitoring programs and management, with the identification of further research needs.

Identification of Mid-Polar and Polar AhR Agonists in Cetaceans from Korean Coastal Waters: Application of Effect-Directed Analysis with Full-Scan Screening.

Major aryl hydrocarbon receptor (AhR) agonists were identified in extracts of blubber, liver, and muscle from six long-beaked common dolphins (Delphinus capensis) and one fin whale (Balaenoptera physalus) collected from Korean coastal waters using effect-directed analysis. Results of the H4IIE-luc bioassay indicated that the polar fractions of blubber and liver extracts from the fin whale exhibited relatively high AhR-mediated potencies. Based on full-scan screening with high-resolution mass spectrometry, 37 AhR agonist candidates, spanning four use categories: pharmaceuticals, pesticides, cosmetics, and natural products, were selected. Among these, five polar AhR agonists were newly identified through toxicological confirmation. Concentrations of polar AhR agonists in cetaceans were tissue-specific, with extracts of blubber and liver containing greater concentrations than muscle extracts. Polar AhR agonists with great log KOA values (>5) were found to biomagnify in the marine food chain potentially. Polar AhR agonists contributed 8.9% of the observed AhR-mediated potencies in blubber and 49% in liver. Rutaecarpine and alantolactone contributed significantly to the total AhR-mediated potencies of blubber, whereas hydrocortisone was a major AhR contributor in the liver of the fin whale. This study is the first to identify the tissue-specific accumulation of polar AhR agonists in blubber and liver extracts of cetaceans.

Use of molecular composition and compound-specific isotope analysis for source appointment of PAHs in sediments of a highly industrialized area.

This study utilized both conventional molecular analysis and compound-specific isotopic techniques to identify the sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Ulsan Bay, South Korea. The concentrations of 15 traditional and 11 emerging PAHs were determined in sediments from 21 source sites and 26 bay sites. The concentrations and compositions of traditional and emerging PAHs varied significantly, even at sites close to the source areas. The results obtained from diagnostic ratios and the positive matrix factorization model for source identification were inconsistent in adjacent source areas. The δ13C profiles of PAHs, such as phenanthrene (Phe), fluoranthene (Fl), pyrene (Py), and benz[a]anthracene (BaA) in the sediments showed distinct features depending on the surrounding sources. In urban sediments, lighter δ13CPhe values were observed (mean: -25.1‰), whereas relatively heavier values of δ13CPy were found in petroleum industry areas (mean: -23.4‰). The Bayesian isotope mixing model indicates that the predominant source of PAHs in Ulsan Bay sediments was the petroleum industry (45%), followed by the non-ferrous metals industry (30%), automobile industry (18%), and urban areas (6.3%). These results demonstrated the utility of stable isotopes in assessing the sources and contributions of PAHs in small-scale regions. However, there are still limitations in compound-specific isotope analysis of PAHs, including insufficient end-members for each source, difficulty in analysis, and the influence of non-point sources; thus, further study is needed to expand its application.

Spatiotemporal variability on local-regional scale in subtidal meiofaunal assemblages along the southern coast of Korea.

This study was conducted to investigate the spatiotemporal variability in subtidal meiofaunal assemblages off the southern coast of Korea at local and regional scales. Abiotic and biotic samples were collected by site (three sites at least 10 km apart) within region (three coastal regions at least 50 km apart) over 7 years (2015-2021). The density and taxon richness of meiofaunal assemblages differed significantly among sites, but not among regions or years. The meiofaunal assemblage composition differed significantly among sites, regions, and years. A distance-based multivariate multiple regression analysis revealed that the mean sediment grain size and total nitrogen, lead, nickel, chromium, and aluminum concentrations were key environmental variables determining the variation of the meiofaunal assemblages. This study can provide basic ecological data for understanding the spatiotemporal distribution of meiofauna assemblages and aid in the development of management strategies to mitigate marine pollution on the southern coast of Korea.

Legacy and novel perfluoroalkyl substances in raw and cooked squids: Perspective from health risks and nutrient benefits.

Perfluoroalkyl substance (PFAS) existed ubiquitously in the environment and could be ingested unconsciously with food which posed a disease risk to human health. Swordtip squid (Uroteuthis edulis) is one of the most popular and highly consumed seafood worldwide, with wide distribution and abundant biomass. Therefore, it is of great importance to the health of the public by reducing the health risks of squid consumption while preserving the benefits of squid to humans. In this study, the PFAS and fatty acids in squids were tested from the southeast coastal regions of China, a major habitat for squids. Relative higher concentrations of PFAS in squid were found in the subtropical zone of southern China (mean: 15.90 ng/g·dw) compared to those of the temperate zone of northern China (mean: 11.77 ng/g·dw). The digestive system had high tissue/muscle ratio (TMR) values, and the pattern of TMR among the same carbon-chain PFAS was similar. Cooking methods have a significant contribution to eliminating PFAS (in squids). PFAS were transferred from squids to other mediums after cooking, so juice and oil should be poured out to minimize PFAS exposure into body. The result showed that squids can be regarded as a healthy food by health benefits associated with fatty acids. Estimated daily intake (EDI) had the highest level in Korea via consuming squids through cooking processes compared with other countries. Based on the assessment of the hazard ratios (HRs), there was a high exposure risk of perfluoropentanoic acid (PFPeA) via taking squids for human health. This research provided the theoretical guidance of aquatic product processing in improving nutrition and reducing harmful substances.

Historical trends of traditional, emerging, and halogenated polycyclic aromatic hydrocarbons recorded in core sediments from the coastal areas of the Yellow and Bohai seas.

Historical trends of polycyclic aromatic hydrocarbons (PAHs) contamination were reconstructed from eleven sediment cores located in intertidal zones of the Yellow and Bohai seas for a period encompassing the last 80 years. The analysis encompassed 15 traditional PAHs (t-PAHs), 9 emerging PAHs (e-PAHs), and 30 halogenated PAHs (Hl-PAHs), including 10 chlorinated PAHs (Cl-PAHs) and 20 brominated PAHs (Br-PAHs). Concentrations of target PAHs were highest in industrial and municipal areas situated along the coast of the Bohai Sea, including Huludao, Yingkou, Tianjin, and Dandong, constituting a substantial mass inventory. All target PAHs showed increasing trends since the 1950s, reflecting the development history of South Korea and China. High molecular weight PAHs accumulated in sampling sites more than low molecular weight PAHs. A positive matrix factorization model showed that the PAH sources were coal and gasoline combustion (35%), diesel combustion (33%), and biomass combustion (32%). Over the last 80 years, the contribution of coal and gasoline combustion increased in all regions, while diesel combustion and biomass combustion varied across regions and over time. Toxicity equivalence values were highest for t-PAHs (>99% contribution), followed by Cl-PAHs, Br-PAHs, and e-PAHs. Concentrations of t-PAHs in Eastern Asia seas have increased since the 1900s, particularly in intertidal areas compared to subtidal areas. The intertidal zone removed 83% of the total flux of PAHs originating from land and thus appears to serve as a buffer zone against marine pollution. Overall, this study provides novel knowledge on the historical trends and sources of PAHs on a large scale, along with insights for future coastal management.

First confirmed report of Nassarius sinarum (Mollusca, Gastropoda) in Korea.

Background: The marine gastropod mollusc Nassarius sinarum has attracted attention due to its status as a potential invasive species and the ecological impact it may have on local environments and the fishing industry. It was observed exclusively within China initially, but its distribution now seems to have expanded into Japan and Korea. Accurate identification of N. sinarum, particularly in its juvenile stage, is vital for understanding its ecological influences and distribution patterns. New information: This study represents the first comprehensive analysis of N. sinarum samples from Korea. It includes morphological examination, scanning electron microscopy images and molecular sequencing. Two live specimens were collected from the Yeongsan River estuary in Korea and their morphological features were analysed and compared to those of samples from China and Japan. The samples' species were confirmed by molecular identification, based on cytochrome c oxidase subunit I (COI) and histone H3 (H3) genetic markers.It was observed that juvenile N. sinarum shells lack key species-characteristic morphological traits, such as a thick outer lip and diminishing axial ribs. However, COI marker-based molecular identification affirmed that these Korean specimens were N. sinarum. The H3 region was registered with the National Center for Biotechnology Information (NCBI) for the first time. Phylogenetic analysis of the H3 region did not resolve species distinctions within the Nassarius, suggesting that the H3 marker is not suitable for species identification within this genus. In this context, multiple genetic markers, when used appropriately, can also be applied to genus-level searches, enhancing species identification accuracy and reducing misidentification.The sequences provided in this study can serve as a valuable reference for future DNA barcoding research. Additional samples and surveys should be conducted through collaborative efforts amongst national and institutional organisations to further clarify the ecological status of N. sinarum and to investigate its distribution and potential impact around East Asia. Finally, a new Korean name, (No-lan-jul-job-ssal-mu-nui-go-dung; 노란줄좁쌀무늬고둥) has been proposed for N. sinarum.

Sphingomicrobium sediminis sp. nov., isolated from marine sediment in the Republic of Korea.

A Gram-stain-negative, rod-shaped, bright-orange coloured bacterium without flagellum, designated as strain GRR-S6-50T, was isolated from a tidal flat of Garorim bay, Taean-gun, Chungcheongbuk-do, Republic of Korea. Cells grew aerobically at 20-37 °C (optimum, 30 °C), pH 7.0-10.0 (optimum, pH 7.0) and with 1-5 % (w/v) NaCl (optimum, 3 %). The 16S rRNA gene sequence analysis demonstrated that strain GRR-S6-50T was closely related to Sphingomicrobium aestuariivivum AH-M8T with a sequence similarity of 97.80 % followed by Sphingomicrobium astaxanthinifaciens CC-AMO-30BT (97.44 %), Sphingomicrobium marinum CC- AMZ-30MT (97.16 %), Sphingomicrobium arenosum CAU 1457T (96.37 %), Sphingomicrobium flavum CC-AMZ-30NT (95.31 %) and Sphingomicrobium lutaoense CC-TBT-3T (95.23 %). The average nucleotide identity and digital DNA-DNA hybridization values with related strains ranged from 74.5 to 77.3% and 21.1 to 35.0 %, respectively. The G+C content of strain GRR-S6-50T was 63.30 mol%. The strain has ubiquinone-10 as the predominant respiratory quinone and the major fatty acids were C18 : 3 ω6c (54.57 %) and C17 : 1 ω6c (10.58 %). The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, three unidentified lipids and one glycolipid. On the basis of the results of phylogenetic, phenotypic and chemotaxonomic studies, strain GRR-S6-50T is regarded to represent a novel species within the genus Sphingomicrobium, for which the name Sphingomicrobium sediminis sp. nov. (KACC 22562T=KCTC 92123T=JCM 35084T) is proposed.

Removing emerging e-waste pollutant DTFPB by synchronized oxidation-adsorption Fenton technology.

Liquid crystal monomers (LCMs), an emerging group of organic pollutants related to electronic waste, have been frequently detected from various environmental matrices, including landfill leachate. The persistence of LCMs requires robust technology for remediation. The objectives of this study were to evaluate the feasibility, performance and mechanism of the remediation of a typical LCM 4-[difluoro(3,4,5-trifluorophenoxy)methyl]- 3,5-difluoro-4'-propylbiphenyl (DTFPB) via synchronized oxidation-adsorption (SOA) Fenton technology and verify its application in DTFPB-contaminated leachate. The SOA Fenton system could effectively degrade 93.5% of DTFPB and 5.6% of its total organic carbon (TOCDTFPB) by hydroxyl radical oxidation (molar ratio of Fe2+ to H2O2 of 1/4 and pH 2.5-3.0) following a pseudo-first-order model under 0.378 h-1. Additionally, synchronized adsorption of DTFPB and its degradation intermediates by in situ resultant ferric particles via hydrophobic interaction, complexation, and coprecipitation contributed to almost 100% of DTFPB and 33.4% of TOCDTFPB removal. Three possible degradation pathways involving eight products were proposed, and hydrophobic interactions might drive the adsorption process. It was first confirmed that the SOA Fenton system exhibited good performance in eliminating DTFPB and byproducts from landfill leachate. This study provides new insights into the potential of the Fenton process for the treatment of emerging LCMs contamination in wastewater.

Cooking methods effectively alter perfluoroalkyl substances and nutrients in cultured and wild bullfrogs.

The ubiquitous distribution of perfluoroalkyl substances (PFASs) poses a threat to the health of aquatic organisms and humans. Bullfrogs are considered a popular aquatic food product in South China, providing high protein and tasty cuisine; however bullfrogs have been shown to contain significant concentrations of PFASs. However, the risk-benefit ratios of PFASs and nutrient contents in cooked bullfrogs are not well understood. PFASs and nutrients were investigated in raw and cooked specimens of cultured and wild bullfrogs in this study. Novel PFASs showed higher detection levels and accumulation in wild bullfrogs than in cultured bullfrogs. Potential factors such as fat and fatty acid ratio affected PFASs accumulation in different tissues and by different cooking methods of bullfrogs. All cooking methods can reduce PFASs in edible tissues while significantly enhancing the nutritive value index (NVI) compared to raw bullfrogs. Steaming was the most effective way to reduce PFASs (rate of reduction was over 66%) and resulted in a lower risk of contributing to arteriosclerosis than other cooking methods assessed by atherogenicity index (AI) values. Cultured bullfrogs instead of wild bullfrogs were recommended for human consumption, and steaming was regarded as a better cooking method in terms of risk-benefit concerns. Overall, this work provides quantitative analysis of cooking methods that alter PFASs and nutrients in bullfrogs.

Methodological advances and future directions of microalgal bioassays for evaluation of potential toxicity in environmental samples: A review.

Microalgal bioassays are widely applied to evaluate the potential toxicity of various persistent toxic substances in environmental samples due to multiple advantages, including high sensitivity, short test duration, and cost-effectiveness. Microalgal bioassay is gradually developing in method, and the scope of application to environmental samples is also expanding. Here, we reviewed the published literature on microalgal bioassays for environmental assessments, focusing on types of samples, sample preparation methods, and endpoints, and highlighted key scientific advancements. Bibliographic analysis was performed with the keywords 'microalgae' and 'toxicity' or 'bioassay', and 'microalgal toxicity'; 89 research articles were selected and reviewed. Traditionally, most studies implementing microalgal bioassays focused on water samples (44%) with passive samplers (38%). Studies using the direct exposure method (41%) of injecting microalgae into sampled water mainly evaluated toxic effects by growth inhibition (63%). Recently, various automated sampling techniques, in situ bioanalytical methods with multiple endpoints, and targeted and non-targeted chemical analyses have been applied. More research is needed to identify causative toxicants affecting microalgae and to quantify the cause-effect relationships. This study provides the first comprehensive overview of recent advances in microalgal bioassays performed with environmental samples, suggesting future research directions based on current understanding and limitations.

Food web dynamics in the mangrove ecosystem of the Pearl River Estuary surrounded by megacities.

Global recognition that mangroves support coastal ecosystem services has increased; however, studies on trophic dynamics in mangrove ecosystems remain limited. We seasonally analysed the δ13C and δ15N of 34 consumers and 5 diets to elucidate the food web dynamics in the Pearl River Estuary (PRE). Fish had a large niche space during the monsoon summer, reflecting increased trophic roles. In contrast, the small niche space of benthos over seasons reflected consistent trophic positions. Consumers mainly utilized plant-derived organic matters in the dry season and particulate organic matters in the wet season. The present study with literature reviews revealed characteristics of the PRE food web with the depleted δ13C and enriched δ15N, indicating a high contribution of mangrove-derived organic carbon and sewage input, particularly in the wet season. Overall, this study confirmed the seasonal and spatial trophic dynamics in mangrove forests surrounding megacities for future sustainable mangrove ecosystem management.

Distribution, compositional characteristics, and historical pollution records of microplastics in tidal flats of South Korea.

Studies on distribution of microplastics (MPs) in sediments of tidal flats are relatively scarce compared to other coastal areas. In this study, spatial and vertical distributions and compositions of MPs in tidal flat sediments along the west coast of Korea were investigated. The abundance of MPs in surface and core sediments ranged from 20 to 325 and 14 to 483 particles per 50 g dry weight, respectively. Polypropylene (51%) and polyethylene (36%) were the most dominant MPs; the size was <0.3 mm, and the shape was mostly fragments followed by fibers. The abundance of MPs in sediments has increased rapidly since the 1970s, and recently showed a slight decrease. Surface morphology of MPs analyzed using a scanning electron microscope revealed that the MPs in tidal flats were highly weathered mechanically and/or oxidatively. The results of this study provide valid baseline data on distributions of MPs in tidal flats.

Characterization of microalgal toxicants in the sediments from an industrial area: Application of advanced effect-directed analysis with multiple endpoint bioassays.

Microalgal toxicants in sediments from an industrialized area (Ulsan Bay) in South Korea were identified using effect-directed analysis (EDA) with full-scan screening analysis (FSA) and microalgal bioassays with multiple endpoints. The growth rate and cell viability of three microalgae (Isochrysis galbana, Dunaliella tertiolecta, and Phaeodactylum tricornutum) were strongly inhibited following exposure to raw organic extracts of sediments from Site D5 (Woehang River). The polar fraction separated using a silica gel column significantly inhibited growth rate, esterase activity, cell membrane intensity, and chlorophyll a autofluorescence. In comparison, non- and mid-polar fractions induced non-toxic or esterase inhibition. Target toxicants, such as polycyclic aromatic hydrocarbons, styrene oligomers, and alkylphenols, were detected at low concentrations (450, 79, and 98 ng g-1 dw, respectively) in the sediment of D5, indicating the presence of unmonitored toxicants. FSA was performed for the polar fraction using LC-QTOFMS, and 31 candidates of toxicants were selected. Toxicological confirmation was conducted for 7 candidates for which standards are available. Out of these, 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol showed significant microalgal toxicity; however, these compounds did not fully explain the induced toxicity. Overall, combining EDA and FSA with multiple endpoint bioassays demonstrated the benefits of characterizing the microalgal toxicants in the environments.

Sources and sequestration rate of organic carbon in sediments of the bare tidal flat ecosystems: A model approach.

Humans have been contributing adversely to greenhouse gas emissions by generating a vast amount of CO2, primarily causing climate change. Nature-based climate solutions, consisting of both terrestrial and marine ecosystems, are tremendous potential for sequestering and storing significant amounts of carbon, which can help to slow the progression of climate change. In this study, we use a carbon balance model to simulate the carbon sequestration rate and carbon stored in bare tidal flat (BTF) areas along Korea's west and south coasts from 2018 to 2050. Furthermore, the percentage of potential carbon sources deposited at BTF sites was calculated using a two-terminal mixing model and δ13C data. The carbon deposited on the BTF areas is the result of lateral carbon transport from upslope terrestrial regions as well as marine sources. Based on the δ13C isotope, this study classified potential carbon sources in BTFs sediment into two categories: terrestrial and marine. The results indicate that the proportion of organic carbon contribution from terrestrial sources ranged from 7.63% to 49% in the BTF studied areas. We discuss the validity of projection which was investigated over three years, from 2018 to 2020. A preliminary conclusion is that future carbon storage at BTF sites will increase significantly. Carbon accumulation increases linearly over time in nearly all areas studied, with carbon sequestration rates ranging from 0.053 to 0.623 (MgC ha-1 yr-1). This study found that a significant amount of carbon is sequestered for a long time in the BTF regions based on model simulation results. In addition, it also contributes to projects that seek to promote and conserve these climate benefits by providing estimates of carbon storage in coastal BTFs that can be included in NDCs for the Paris Agreement.

Insight into the Effect of Sulfonation Techniques on the Adsorption Properties of -SO3H Surface-Functionalized Coal as Adsorbent for Malachite Green Dye: Steric and Energetic Investigation.

Natural coal (N.C) was sulfonated with sulfuric acid by normal stirring (MS.C) and sonication waves (SS.C) to obtain -SO3H functionalized coal as enhanced adsorbents of malachite green dye (MG). The sulfonated products exhibit enhanced surface area (MS.C (27.2 m2/g) and SS.C (45.8 m2/g)) as compared to N.C. SS.C achieved higher acid density (14.2 mmol/g) and sulfur content (13.2 wt. %) as compared to MS.C. The impact of the sulfonation processes on the adsorption of MG was assessed based on the monolayer isotherm model of one energy. The MG Q sat of N.C (121.3 mg/g), MS.C (226.3 mg/g), and SS.C (296.4 mg/g) validate the significant effect of the sulfonation processes by the sonication waves. This is in agreement with the active site densities that reflect the saturation of SS.C by more active sites (180.74 mg/g) than MS.C (120.38 mg/g) and N.C (70.84 mg/g). The MS.C and SS.C can adsorb three MG molecules as compared to two molecules per site of N.C. The Gaussian energy (<8 kJ/mol) and adsorption energy (<40 kJ/mol)) reflects the physisorption of MG involving van der Waals forces, hydrogen bonding, and dipole bonding forces. The thermodynamic functions demonstrate the uptake of MG by exothermic, spontaneous, feasible reactions.