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Around one-third of the world's most carbon-rich ecosystems, mangrove forests, have already been destroyed in Thailand owing to coastal development and aquaculture. Improving these degraded areas through mangrove plantations can restore various coastal ecosystem services, including CO 2 absorption and protection against wave action. This study examines the biomass of three coastal mangrove plantations (Avicennia alba) of different ages in Samut Prakarn province, Central Thailand. Our aim was to understand the forest biomass recovery during the early stages of development, particularly fine root biomass expansion. In the chronosequence of the mangrove plantations, woody biomass increased by 40% over four years from 79.7 ± 11.2 Mg C ha -1 to 111.7 ± 12.3 Mg C ha -1 . Fine root biomass up to a depth of 100 cm was 4.47 ± 0.33 Mg C ha -1 , 4.24 ± 0.63 Mg C ha -1 , and 6.92 ± 0.32 Mg C ha -1 at 10, 12, and 14 year-old sites, respectively. Remarkably, the fine root biomass of 14-year-old site was significantly higher than those of the younger sites due to increase of the biomass at 15-30 cm and 30-50 cm depths. Our findings reveal that the biomass recovery in developing mangrove plantations exhibit rapid expansion of fine roots in deeper soil layers., (© 2024. The Author(s).)

The climate of the world today has changed greatly. This is mainly due to human activity causing large emissions of carbon dioxide (CO2) from the reserve into the atmosphere, which is the main cause of global warming. This research methodology comprised of training for people in the community and local government sector, so they acquired knowledge and understanding of the causes and consequences of global warming. The people will also learn the adjustment toward weather atmosphere, the method in relieving global warming issues with the potential of the community forest as well as tree measurement techniques. The research method was based from the analysis of the carbon stock from the community forest from 3 different methods; which are 1) method of tree measurement by farmers in the community 2) Measurement, Reporting and Verification (MRV) online method, and 3) the application of Geoinformatics Technology (GIT). The research results found that 50 participants in the training session possessed over 80 percent of understanding toward causes and consequences from global warming, adjustment toward the change of weather atmosphere, and way to relieve the severity of global warming issue with a potential of community forest. Participants were also able to learn tree measurement techniques as well as able to record results. The results from the data analysis from the field survey, MRV online tool, and Geoinformatics Technology found that the community forest can complete the process of carbon stock that is equivalent to 5,256.66 tCO2e, 5,061.32 tCO2e, 5,058.01 tCO2e respectively. [ABSTRACT FROM AUTHOR]

Mangrove forests can help to mitigate climate change by storing a significant amount of carbon (C) in soils. Planted mangrove forests have been established to combat anthropogenic threats posed by climate change. However, the efficiency of planted forests in terms of soil organic carbon (SOC) storage and dynamics relative to that of natural forests is unclear. We assessed SOC and nutrient storage, SOC sources and drivers in a natural and a planted forest in southern Thailand. Although the planted forest stored more C and nutrients than the natural forest, the early-stage planted forest was not a strong sink relative to mudflat. Both forests were predominated by allochthonous organic C and nitrogen limited, with total nitrogen being a major driver of SOC in both cases. SOC showed a significant decline along land-to-sea and depth gradients as a result of soil texture, nutrient availability, and pH in the natural forest., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: PEI SUN LOH reports financial support was provided by Asia-pacific Network for Global Change Research. CHOON WENG LEE, CHUI WEI BONG reports financial support was provided by Ministry of Higher Education Malaysia for the HICoE Phase II fund (HICoE IOES-2023C). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

There have been a very limited number of systematic studies on PM 2.5 compositions and their source contribution in Southeast Asia. This study aims to explore the characteristics of PM 2.5 composition collected in Chiang Mai (Thailand) during La Niña and El Niño years and to apportion their sources during smoke haze and non-haze periods. The average PM 2.5 concentration of smoke haze episode in 2019 (El Niño) was much higher than in 2017 (La Niña). The ratios of organic carbon (OC) to elemental carbon (EC), as well as K (biomass burning (BB) tracer) to PM 2.5 , were higher during smoke haze episodes in 2019 than in 2017 indicating a significant influence from BB. The ratios of secondary organic carbon (SOC) levels to primary organic carbon (POC) levels during smoke haze episodes were higher than those in non-haze period, which indicated greater SOC contributions or more photo-oxidation of precursors in haze episodes with high ambient temperatures. However, the ratios of soil markers (Ca and Mg) during non-haze period were high implying that soil source contributed more to PM 2.5 concentrations when there less BB occurred. The positive Matrix Factorization (PMF) model revealed that the source of BB, characterized by high K fractions, was the largest contributor during smoke haze episodes accounting for 50% (2017) and 79% (2019). Climate conditions influence meteorological patterns, particularly during incidences of extreme weather such as droughts, which affect the scale and frequency of open burning and thus air pollution levels., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Seagrass ecosystems are important organic carbon (C org ) sinks with great potential to contribute to climate change mitigation strategies. However, the high spatial and temporal variability is a barrier to the accurate assessment of national C org stocks. This study provides a national assessment of C org within seagrass meadows, including spatial and temporal variations. The highest C org stocks were within mangrove-associated (44.3 ± 8.27 Mg ha -1 ), while near-surface sediments were highest in reef-associated meadows (10.20 ± 3.69 Mg ha -1 ). Regionally, the highest stocks were in the Upper Andaman coast in monospecific meadows (51.7 ± 7.14 Mg ha -1 ). C org stocks in near-surface sediments were significantly different across historical trends (p < 0.001), with the highest stocks in stable meadows (9.28 ± 3.39 Mg ha -1 ). The national C org stock within seagrass meadows sediment was 40.45 ± 11.59 Mg C ha -1 . The results of this study highlighted the complexity of blue carbon in seagrass meadows and the associated impacts on national C org assessments, carbon accounting, and conservation strategies., Competing Interests: Declaration of competing interest Anchana Prathep, Milica Stankovic and Janmanee Panyawai report financial support from Center of Excellence on Biodiversity grant (2563-BCD-PG2-163003) for the project “Seagrass and it's blue carbon under the climate change world Anchana Prathep, Milica Stankovic and Janmanee Panyawai report the support from Program Management Unit for Human Resources & Institutional Development, Research and Innovation (PMU-B) on a project (B13F660071) “Capacity building on Nature based Solution for Carbon Net Zero”. Nattacha Khanthasimachalerm has nothing to declare., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Atmospheric particulate matter smaller than 2.5 micron (PM 2.5 ) was evaluated at four sites in the lower southern part of Thailand during 2019-2020 to understand the impact of PM 2.5 transport from peatland fires in Indonesia on air quality during the southwest monsoon season. Mass concentration and chemical bound-PM, including carbon composition, e.g., organic carbon (OC) and elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs), and inorganic elements, were analyzed. The PM 2.5 emission sources were identified by principal components analysis (PCA). The average mass concentrations of PM 2.5 in the normal period, which represents clean background air, from four sites was 3.5-5.1 µg/m 3 , whereas during the haze period, it rose to 5.4-13.5 µg/m 3 . During the haze period, both OC and EC were 3.5 times as high as in the normal period. The average total PAHs and BaP-TEQ of PM 2.5 during the haze period were ~ 1.3-1.7 and ~ 1.2-1.9 times higher than those in the normal period. The K concentrations significantly increased during haze periods. SO 4 2- dominated throughout the year. The effects of external sources, especially the transboundary haze from peatland fires, were significantly enhanced, because the background air in the study locations was generally clean. PCA indicated that vehicle emission, local biomass burning, and secondary particles played a key role during normal period, whereas open biomass burning dominated during the haze phenomena. This was consistent with the OC/EC and PAH diagnostic ratios. Backward trajectories confirmed that the sources of PM during the haze period were predominantly peatland fires in Sumatra, Indonesia, due to southwest wind., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The tropical forest carbon (C) balance threatened by extensive socio-economic development in the Greater Mekong Subregion (GMS) in Asia is a notable data gap and remains contentious. Here we generated a long-term spatially quantified assessment of changes in forests and C stocks from 1999 to 2019 at a spatial resolution of 30 m, based on multiple streams of state-of-the-art high-resolution satellite imagery and in situ observations. Our results show that (i) about 0.54 million square kilometers (21.0% of the region) experienced forest cover transitions with a net increase in forest cover by 4.3% (0.11 million square kilometers, equivalent to 0.31 petagram of C [Pg C] stocks); (ii) forest losses mainly in Cambodia, Thailand, and in the south of Vietnam, were also counteracted by forest gains in China due mainly to afforestation; and (iii) at the national level during the study period an increase in both C stocks and C sequestration (net C gain of 0.087 Pg C) in China from new plantation, offset anthropogenetic emissions (net C loss of 0.074 Pg C) mainly in Cambodia and Thailand from deforestation. Political, social, and economic factors significantly influenced forest cover change and C sequestration in the GMS, positively in China while negatively in other countries, especially in Cambodia and Thailand. These findings have implications on national strategies for climate change mitigation and adaptation in other hotspots of tropical forests., (© 2023 John Wiley & Sons Ltd.)

Biomass burning (BB) is an important contributor to the air pollution in Southeast Asia (SEA), but the emission sources remain great uncertainty. In this study, PM 2.5 samples were collected from an urban (Chiang Mai University, CMU) and a rural (Nong Tao village, NT) site in Chiang Mai, Thailand from February to April (high BB season, HBB) and from June to September (low BB season, LBB) in 2018. Source apportionment of carbonaceous aerosols was carried out by Latin Hypercube Sampling (LHS) method incorporating the radiocarbon ( 14 C) and organic markers (e.g., dehydrated sugars, aromatic acids, etc.). Thereby, carbonaceous aerosols were divided into the fossil-derived elemental carbon (EC f ), BB-derived EC (EC bb ), fossil-derived primary and secondary organic carbon (POC f , SOC f ), BB-derived OC (OC bb ) and the remaining OC (OC nf, other ). The fractions of EC bb generally prevailed over EC f throughout the year. OC bb was the dominant contributor to total carbon with a clear seasonal trend (65.5 ± 5.8 % at CMU and 79.9 ± 7.6 % at NT in HBB, and 39.1 ± 7.9 % and 42.8 ± 4.6 % in LBB). The distribution of POC f showed a spatial difference with a higher contribution at CMU, while SOC f displayed a temporal variation with a greater fraction in LBB. OC nf, other was originated from biogenic secondary aerosols, cooking emissions and bioaerosols as resolved by the principal component analysis with multiple liner regression model. The OC nf, other contributed within a narrow range of 6.6 %-14.4 %, despite 34.9 ± 7.9 % at NT in LBB. Our results highlight the dominance of BB-derived fractions in carbonaceous aerosols in HBB, and call the attention to the higher production of SOC in LBB., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The carbon storage value of forest restoration, by the framework species method (FSM) in northern Thailand, was assessed for trees (using a partial harvesting technique) and soil and compared with restoration costs. Forest carbon accumulation amounted to 143.08 tC/ha in trees and 8.56 tC/ha in soil over 14 years, with a combined value of USD 27,173.63 (net present value (NPV), discounted at 2.85%/year)) (at the current European carbon credit (EUA) price of 55.98 EUR/tCO2 = 242.21 USD/tC). Restoration costs increased from 2190.27 to 5680.72 USD/ha with declining pre-existing natural regeneration or 3.99–10.34 USD per ton of sequestered CO2. Profits over 14 years ranged in NPV from 22,215.45 to 25,157.04 USD/ha, breaking even from just over 4 years to just under 7, respectively. In contrast, profits from maize cultivation (a major regional deforestation driver) averaged 96.25 USD/ha/year, or just 1347.53 USD/ha over 14 years. Consequently, forest restoration could become a financially attractive alternative land use, provided an open, transparent, carbon market is created. Therefore, this study supports creation of a forest-carbon trading system in Thailand, to incentivize forest restoration and fire prevention, increase farmers' incomes, reduce smoke-related public health problems, protect watersheds, and conserve biodiversity. [ABSTRACT FROM AUTHOR]

Fire has been used for land clearing under rotational shifting cultivation (RSC) in Northern Thailand for a long time. However, the effects of fire on soil organic carbon (SOC), soil total nitrogen (STN), and soil properties are not well understood. We determined SOC, STN, and soil properties of the topsoil layer (0-30 cm) along a fallow chronosequence under RSC and assessed how fire affects SOC, STN, and soil properties. Eight fields at Ban Mae Pok, Mae Chaem District, Chiang Mai Province, Northern Thailand, were investigated. The levels of SOC, STN, and soil properties were observed at three time points: pre-burning, post-burning (5 minutes after burning), and post-harvest (nine months after burning). The highest SOC and STN stocks, organic matter (OM), and clay content were observed for the longest fallow period (7 years fallow), whereas the shortest period (1 year fallow) resulted in the lowest SOC and STN stocks. Fire caused no significant changes in SOC, STN, and some soil properties (soil texture, available P, exchangeable K, exchangeable Ca, exchangeable Mg, bulk density, and OM) because of the low fire intensity and short fire duration. Only pH and electrical conductivity were significantly increased (p ≤ 0.05) after burning due to the demobilization of base cations in burnt vegetation and incorporation into the soil with ashes and wood charcoal. Although fire may still be necessary for RSC, maintaining the fire intensity below 380 °C to reduce SOC losses and appropriate post-fire management strategies to reduce STN losses are crucial., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Mangroves are increasingly recognized as an important component of regional and global carbon cycles especially for their high carbon storage capacity. Global estimation of mangrove soil organic carbon (SOC) storage requires detailed regional studies, but estimates of SOC data in deep soils are currently missing in many countries. Furthermore, little is explored on the molecular composition of mangrove SOC. Here, we assessed the SOC stock in a Trat mangrove forest (Thailand) by collecting deep soils (3.5 m) and analyzed the SOC composition for better understanding its potential sources and influencing factors. The Trat mangrove forest had four times higher SOC stock than has been considered for Thai mangrove forests, with the per-area SOC stock of nearly 1000 Mg C ha -1 which rivals that of Indo-Pacific mangrove forests. The SOC composition analyzed by C/N ratios and spectroscopic techniques differed by tree species and depth. Compositional data principal component analysis revealed that a biological factor (root abundance) had stronger influences than the soil texture (sand versus clay) on the abundance and composition of mangrove SOC. Although surface soil (~1 m) C density was largely controlled by the recent vegetation, deep soil C density reflected other historical processes. This study contributed to a refined estimate of Thailand mangrove SOC stock and revealed that factors influencing SOC abundance and composition differ by tree species and depth., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

• Carbon footprint of a sample of home-stays in Thailand is assessed. • Carbon performance of home-stays against hotels is compared. • On average, home-stays generate 1.3 tonnes of CO2-eq. per home-stay per year. • This is equivalent to 0.32 kg of CO2-eq. per 'per guest night'. Home-stays represent a popular category of tourist accommodation in South-East Asia but their carbon footprint has not been systematically assessed. This hampers an understanding of the energy consumption patterns of home-stays, impedes identification of the main carbon hotspots in home-stay operations and prevents a comparative analysis of the carbon performance of home-stays against other tourist accommodation categories. Using the method of screening Life Cycle Energy Analysis (LCEA), this study assessed the carbon footprint of a sample of home-stays in Thailand and undertook its comparative analysis against other categories of tourist accommodation, globally and in Thailand. The overall annual carbon footprint of home-stays was assessed as low (1.3 tonnes of CO 2 -eq. per home-stay on average) which was due to small size and limited guest amenities. The 'per guest night' carbon footprint of home-stays was comparable to that of budget hotels in Thailand (0.32 kg of CO 2 -eq. per home-stay on average) which was attributed to low occupancy driven by high demand seasonality. [ABSTRACT FROM AUTHOR]

Organic rice farming is a sustainable rice cultivation system that eliminates chemical inputs and has the potential to reduce environmental impacts. This study aims to: 1) evaluate and compare the carbon footprint intensity and the value of carbon sequestration ecosystem services (VCSES) between organic rice farming (OF) and conventional rice farming (CF) and 2) estimate the impact of climate change on soil organic carbon (SOC), rice yield, and VCSES of two farming types in Phichit province, Thailand. The results showed that the carbon footprint intensity in OF and CF were significantly different with -0.13 and 0.82 kg CO 2 eq kg -1 rice yield, respectively. The differences in SOC stocks (ΔSOCS) were more significant in OF with the increase of 1107.6 kg C ha -1 year -1 (4061.2 kg CO 2 eq ha -1 year -1 ), while the ΔSOCS value in CF was 625 kg C ha -1 year -1 (2291.7 kg CO 2 eq ha -1 year -1 ). The VCSES in OF (541,196 US$ ha -1 year -1 ) was nearly two times higher than in CF (305,388 US$ ha -1 year -1 ). Under future climate change, rice yields of both farming types are expected to increase under Representative Concentration Pathway (RCP) 2.6, RCP4.5, and RCP6.0, and it will decline under RCP8.5. The SOC and VCSES values are predicted to increase, except under RCP8.5. The dramatic declines can be found from the near future (2020-2039) to the very far future (2080-2099) period. Our finding indicates that even though climate change will have negative effects on SOC and VCSES, the OF will have less impact compared with CF., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Since the 1990s, CO2 emissions have increased steadily in line with the growth of production and the use of energy in the manufacturing sector in Thailand. The Logarithmic Mean Divisia Index Method is used for analysing the sources of changes in CO2 emissions as well as the CO2 emission intensity of the sector in 2000–2018. On average throughout the period, both the amount of CO2 emissions and the CO2 emission intensity increased each year relative to the baseline. The structural change effect (effect of changes of manufacturing production composition) reduced, but the intensity effect (effect of changes of CO2 emissions of individual industries) increased the amount of CO2 emissions and the CO2 emission intensity. The unfavourable CO2 emission intensity change came from the increased energy intensity of individual industries. The increased use of coal and electricity raised the CO2 emissions, whereas the insignificant change in emission factors showed little impact. Therefore, the study calls for policies that decrease the energy intensity of each industry by limiting the use of coal and reducing the electricity used by the manufacturing sector so that Thailand can make a positive contribution to the international community's effort to achieve the goal of CO2 emissions reduction. [ABSTRACT FROM AUTHOR]

Light-absorbing organic carbon (or brown carbon, BrC) has been recognized as a critical driver in regional-to-global climate change on account of its significant contribution to light absorption. BrC sources vary from primary combustion processes (burning of biomass, biofuel, and fossil fuel) to secondary formation in the atmosphere. This paper investigated the light-absorbing properties of BrC such as site-specific mass absorption cross-section (MAC BrC ), absorption Ångström exponent (AAE BrC ), and the absorbing component of the refractive index (k BrC ) by using light absorption measurements from a 7-wavelength aethalometer over an urban environment of Chiang Mai, Thailand in northern peninsular Southeast Asia (PSEA), from March to April 2016. The contribution of BrC to total aerosol absorption (mean ± SD) was 46 ± 9%, 29 ± 7%, 24 ± 6%, 20 ± 4%, and 15 ± 3% at 370, 470, 520, 590, and 660 nm, respectively, highlighting the significant influence of BrC absorption on the radiative imbalance over northern PSEA. Strong and significant associations between BrC light absorption and biomass-burning (BB) organic tracers highlighted the influence of primary BB emissions. The median MAC BrC and k BrC values at 370 nm were 2.4 m 2  g -1 and 0.12, respectively. The fractional contribution of solar radiation absorbed by BrC relative to BC (mean ± SD) in the 370-950 nm range was estimated to be 34 ± 7%, which can significantly influence the regional radiation budget and consequently atmospheric photochemistry. This study provides valuable information to understand BrC absorption over northern PSEA and can be used in model simulations to reassess the regional climatic impact with greater accuracy., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding financial funding and the publication of this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Atmospheric size-classified particles in sizes ranging from small to nanoparticles (PM 0.1 ) are reported for Rangsit City in the Bangkok Metropolitan Region (BMR) of Thailand, for October 2019 (wet season) and January-February 2020 (dry season). The sampling involved the use of a PM 0.1 cascade air sampler to determine the mass concentration. The PMs consisted of six stages including TSP-PM 10 , PM 2.5-10 , PM 1.0-2.5, PM 0.5-1.0, PM 0.5-1.0 and PM 0.1 . Elemental carbon (EC) and organic carbon (OC) were evaluated by a carbon analyzer following the IMPROVE&#95;TOR protocol. The average PM 0.1 mass concentrations were found to be 13.47 ± 0.79 (wet season) and 18.88 ± 3.99 (dry season) μg/m 3 , respectively. The average OC/EC ratio for the rainy season was lower than that in the dry season. The char-EC/soot-EC ratios were consistently below 1 for the PM 0.1 fraction in both seasons indicating that vehicular traffic appeared to be the main emission source. However, the influence of open biomass burning on fine and coarse PM particles on local air pollution was found to be an important issue during the wet season. In addition, long-range transport from other countries may also contribute to the carbon content in the Bangkok Metropolitan Region (BMR) atmosphere during the dry season. The higher secondary organic carbon to organic carbon (SOC/OC) ratio in the dry season is indicative of the contribution of secondary sources to the formation of PM, especially finer particles. A strong correlation between OC and EC in nanoparticles was found, indicating that they are derived from sources of constant emission, likely the diesel engines. Conversely, the OC and EC correlation for other size-specific PMs decreased during the dry season, indicating that these emission sources were more varied., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Although seagrass ecosystems provide various ecosystem services, the implications in correspondence with temporal changes of the meadows is lacking. In this study, we analyzed two-decade changes of the seagrass area with the organic carbon storage and the sources at Libong island in Thailand. The seagrass area covered 841 ha in 2019, after two decades of decline (3.2 and 0.6% yr -1 between 2004 and 2009 and 2009-2019, respectively). Although δ 13 C was not significant between depth layers (p > 0.05), the general trend suggested that the terrestrial source of carbon is dominating bottom depth layer (31.7-37.2%), mixture of terrestrial (19.7-30.3%), seagrass (22.9-29.6%), mangrove (16.8-43.0%) and CPOM (11.2-25.4%) in the middle, and mangroves and seagrasses are dominating surface layer (28.3-66.2 and 29.3-36.5%, respectively). These trends approximately correspond to the areal changes of the meadows, as well as changes of urban area and water quality, providing detailed information on the meadow changes and possible causes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

An improved understanding of the historical variation in the emissions and sources (biomass burning, BB vs. fossil fuel, FF combustion) of soot and char, the two components of black carbon (BC), and polycyclic aromatic compounds (PACs) may help in assessing the environmental effects of the Atmospheric Brown Cloud (ABC) in SE Asia. We therefore determined historical variations of the fluxes of soot, char, and PACs (24 polycyclic aromatic hydrocarbons (PAHs), 12 oxygenated PAHs (OPAHs), and 4 azaarenes) in a dated sediment core (covering the past ∼150 years) of Phayao Lake in Thailand. The soot fluxes have been increasing in recent times, but at a far lower rate than previously estimated based on BC emission inventories. This may be associated with a decreasing BB contribution as indicated by the decreasing char fluxes from old to young sediments. The fluxes of high- and low-molecular-weight (HMW and LMW) PAHs, OPAHs, and azaarenes all sharply increased after ∼1980, while the ΣLMW-/ΣHMW-PAHs ratios decreased, further supporting the reduction in BB contribution at the expense of increasing FF combustion emissions. We also suggest that the separate record of char and soot, which has up to now not been done in aerosol studies, is useful to assess the environmental effects of ABC because of the different light-absorbing properties of these two BC components. Our results suggest that besides the establishment of improved FF combustion technology, BB must be further reduced in the SE Asian region in order to weaken the ABC haze., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Transboundary and domestic aerosol transport during 2018-2019 affecting Bangkok air quality has been investigated. Physicochemical characteristics of size-segregated ambient particles down to nano-particles collected during 2017 non-haze and 2018-2019 haze periods were analyzed. The average PM 2.5 concentrations at KU and KMUTNB sites in Bangkok, Thailand during the haze periods were about 4 times higher than in non-haze periods. The highest average organic carbon and elemental carbon concentrations were 4.6 ± 2.1 µg/m 3 and 1.0 ± 0.4 µg/m 3 , respectively, in PM 0.5-1.0 range at KU site. The values of OC/EC and char-EC/soot-EC ratios in accumulation mode particles suggested the significant influence of biomass burning, while the nuclei and coarse mode particles were from mixed sources. PAH concentrations during 2018-2019 haze period at KU and KMUTNB were 3.4 ± 0.9 ng/m 3 and 1.8 ± 0.2 ng/m 3 , respectively. The PAH diagnostic ratio of PM 2.5 also suggested the main contributions were from biomass combustion. This is supported by the 48-hrs backward trajectory simulation. The higher PM 2.5 concentrations during 2018-2019 haze period are also associated with the meteorological conditions that induce thermal inversions and weak winds in the morning and evening. Average values of benzo(a)pyrene toxic equivalency quotient during haze period were about 3-6 times higher than during non-haze period. This should raise a concern of potential human health risk in Bangkok and vicinity exposing to fine and ultrafine particulate matters in addition to regular exposure to traffic emission., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

We used the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to simulate elemental carbon (EC) concentrations in Thailand in 2017. The goals were to quantify the respective contributions of local emissions and regional transport outside Thailand to EC pollution in Thailand, and to identify the most effective emission control strategy for decreasing EC pollution. The simulated EC concentrations in Chiang Mai, Bangkok, and Phuket were comparable with the observation data. The correlation coefficient between the simulated and observed EC concentrations was 0.84, providing a good basis for evaluating EC sources in Thailand. The simulated mean EC concentration over the whole country was the highest (1.38 μg m -3 ) in spring, and the lowest (0.51 μg m -3 ) in summer. We conducted several sensitivity simulations to evaluate EC sources. Local emissions (including anthropogenic and biomass burning emissions) and regional transport outside Thailand contributed 81.2% and 18.8% to the annual mean EC concentrations, respectively, indicating that local sources played the dominant role for EC pollution in Thailand. Among the local sources, anthropogenic emissions (including the industry, power plant, residential, and transportation sectors) and biomass burning contributed 75.1% and 6.1% to the annual mean EC concentrations, respectively. As the anthropogenic emissions dominated the EC pollution, we performed four sensitivity simulations by reducing 30% of the emissions from each of the industry, power plant, residential, and transportation sectors in Thailand. The results indicated that controlling transportation emissions in Thailand was the most effective way in reducing the EC pollution. The 30% reduction of transportation emissions decreased the annual mean EC concentrations by 12.1%. In contrast, 30% reductions of the residential, industry, and power plant emissions caused 8.4%, 6.4%, and 4.0% decreases in the annual mean EC concentrations, respectively. The model results could potentially provide useful information for air pollution control strategies in Thailand., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Humic-like substances (HULIS) are complex mixtures that are highly associated with brown carbon (BrC) and are important components of biomass burning (BB) emissions. In this study, we investigated the light absorption, emission factors (EFs), and amounts of HULIS emitted from the simulated burning of 27 types of regionally important rainforest biomass in Southeast Asia. We observed that HULIS had a high mass absorption efficiency at 365 nm (MAE 365 ), with an average value of 2.6 ± 0.83 m 2  g -1  C. HULIS emitted from BB accounted for 65% ± 13% of the amount of water-soluble organic carbon (WSOC) and 85% ± 10% of the light absorption of WSOC at 365 nm. The EFs of HULIS from BB averaged 2.3 ± 2.1 g kg -1 fuel, and the burning of the four vegetation subtypes (herbaceous plants, shrubs, evergreen trees, and deciduous trees) exhibited different characteristics. The differences in EFs among the subtypes were likely due to differences in lignin content in the vegetation, the burning conditions, or other factors. The light absorption characteristics of HULIS were strongly associated with the EFs. The annual emissions (minimum-maximum) of HULIS from BB in this region in 2016 were 200-371 Gg. Furthermore, the emissions from January to April accounted for 99% of the total annual emissions of HULIS, which is likely the result of the burning activities during this season. The most significant emission regions were Cambodia, Burma, Thailand, and Laos. This study, which evaluated emissions of HULIS by simulating open BB, contributes to a better understanding of the light-absorbing properties and regional budgets of BrC in this region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Dissolved inorganic carbon isotope composition (δ 13 C DIC ), together with major ion concentrations were measured in the Mun River and its tributaries in March 2018 to constrain the origins and cycling of dissolved inorganic carbon. In the surface water samples, the DIC content ranged from 185 to 5897 μmol/L (average of 1376 μmol/L), and the δ 13 C DIC of surface water ranged from -19.6‱ to -2.7‱. In spite of the high variability in DIC concentrations and partial pressure of carbon dioxide ( p CO 2 ), the δ 13 C DIC values of the groundwater were relatively consistent, with a mean value of -16.9 ± 1.4‱ ( n = 9). Spatial changes occurred in the direction and magnitude of CO 2 flux through water-air interface ( F CO2 ). In the dry season, fluxes varied from -6 to 1826 mmol/(m 2 ·d) with an average of 240 mmol/(m 2 ·d). In addition to the dominant control on hydrochemistry and dissolved inorganic carbon isotope composition by the rock weathering, the impacts from anthropogenic activities were also observed in the Mun River, especially higher DIC concentration of waste water from urban activities. These human disturbances may affect the accurate estimate contributions of carbon dioxide from tropical rivers to the atmospheric carbon budgets.

Size-segregated ambient particles down to particles smaller than 0.1 μm (PM 0.1 ) were collected during the year 2014-2015 using cascade air samplers with a PM 0.1 stage, at two cities in Thailand, Bangkok and Chiang Mai. Their characteristics and seasonal behavior were evaluated based on the thermal/optical reflectance (IMPROVE&#95;TOR) method. Diagnostic indices for their emission sources and the black carbon (BC) concentration were assessed using an aethalometer and related to the monthly emission inventory (EI) of particle-bound BC and organic carbon (OC) in order to investigate the contribution of agricultural activities and forest fires as well as agro-industries in Thailand. Monthly provincial EIs were evaluated based on the number of agricultural crops produced corresponding to field residue burning and the use of residues as fuel in agro-industries, and also on the number of hot spots from satellite images corresponding to the areas burned by forest fires. The ratio of char-EC/soot-EC describing the relative influence of biomass combustion to diesel emission was found to be in agreement with the EI of BC from biomass burning in the size range <1 μm. This was especially true for PM 0.1 , which usually tends to be indicative of diesel exhaust particles, and was shown to be very sensitive to the EI of biomass burning. In Chiang Mai, the northern part of Thailand, the forest fires located upwind of the monitoring site were found to be the largest contributor while the carbon behavior at the site in Bangkok was better accounted for by the EI of provinces in central Thailand including Bangkok and its surrounding provinces, where the burning of crop residues and the cultivation of sugarcane for sugar production are significant factors. This suggests that the influence of transportation of polluted air masses is important on a multi-provincial scale (100-200 km) in Thailand., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

C and N species, including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), dissolved organic nitrogen (DON), NO₃ - and NH₄⁺ contents in 57 river water samples collected from the Mun River of Thailand were measured to determine the relationships between these dissolved load species and their impacts on the environment. DOC values varied between 1.71 and 40.08 mg/L, averaging 11.14 mg/L; DON values ranged from 0.20 to 1.37 mg/L, with an average value of 0.48 mg/L; NO₃ - -N values averaged 0.18 mg/L; and NH₄⁺-N values averaged 0.15 mg/L. DOC contents increased while DON and NO₃ - values decreased along the flow direction. The concentrations of NH₄⁺ maintained the same level in the whole watershed. DOC and DON values exhibited clearly higher concentrations in comparison with other rivers worldwide and were inextricably linked with anthropogenic inputs. The relationships of DOC, DON, and anthropogenic ions imply that there are two different anthropogenic sources (industrial activities and agricultural activities) of the dissolved load in the Mun River watershed. The limited correlations between the DON, NO₃ - , and NH₄⁺ indicate that the N species are not dominated by a single factor, and reciprocal transformations of riverine N pool are complex. Based on the environmental water quality standard reported by the EC (European Communities) and the World Health Organization, assessments of the water quality using the parameters of pH, dissolved oxygen (DO), NO₃ - , NH₄⁺, and TN (total nitrogen) in the Mun River were conducted. The results demonstrate that the river water faces potential environmental pollution, and anthropogenic inputs endanger local water quality and the aquatic community. Therefore, the local government should restrict and reduce the anthropogenic inputs discharged in to rivers, and launch long-term monitoring of water quality.

Regarding the honey industry, market prices are strongly affected by the origin and composition of products. In particular, the adulteration of honey can be divided into cases of honey being mixed with artificial syrup, the different origin of the adulteration and the presence of cane sugar residue. Unfortunately, recent studies mentioned that most honey is mixed with artificial syrups. Thus, determining such unnaturally present sugar is necessary to maintain the trust of the consuming populations. To investigate the possibility of syrup augmentation, this study first clarifies two points of great importance. First, long-term feeding of cane sugar to honey bee colonies in winter and the continuous harvest of honey were investigated to evaluate the C 4 sugar ratio in spring through inspection of the 13 C/ 12 C isotopic ratio. As the results indicated, C 4 sugar was detected as "sugar residue" in honey samples when the honey bee colonies were fed with cane sugar in winter and when the honey was collected in the first and second harvests in March. As indicated from the samples of 89 Taiwanese longan honeys, 54 Thai longan honeys, and 20 Taiwanese non-longan honeys for analysis, such "sugar residues" were in 40% (8/20) of the Taiwanese non-longan honeys, 15% (3/20) of 2017 Taiwanese longan honeys and 20% (4/20) of 2017 Thai longan honeys; these samples were classified as adulterated honey (C 4 % > 7). Second, as revealed in the honeys' protein contents, statistically significant differences were found between Taiwanese (>1.00 mg/g) and Thai longan honeys (<1.00 mg/g). Apparently, this significant difference could be used to classify the difference in origins of longan honeys. This novel inspection of "sugar residue" and "origin" in honey could represent the first attempt for a protocol to guarantee both the quality and quantity assurance of honey in the marketplace., (Copyright © 2018. Published by Elsevier Taiwan LLC.)

Objective: This research aimed to investigate the carbon equivalences associated with the unit processes of municipal solid waste management (MSWM) in Nonthaburi municipality. In addition, factors affecting MSWM's carbon-related activities were determined to find the reduction potential of carbon emissions into the atmosphere., Material and Method: Afield survey was conducted to quantify the amount of resources used in MSWM. Then, they were evaluated in terms of carbon equivalences occurring in the process scheme and categorized into carbon emissions, fixation and reduction,following a carbon-balanced model., Results: From carbon balance analysis of the base-line-scenario MSWM, the carbon emissions were found to be -2,374.56 MTCE/y, resulting in the average carbon unit of-22.98 kg CE/ton solid waste. The negative sign indicates a carbon reduction, instead of an emission,from this MSWM practice, which helps to reduce the concentration of carbon dioxide in the atmosphere., Conclusion: The results of the model reveal that the highest contribution to carbon reduction potential in MSWM is recycling. Accordingly, it is strongly recommended that a policy promoting reuse, recovery, and recycling be pursued in every step of MSWM to assist in, not only extending landfill service life span, but also alleviating the increasing global warming problems.

Stable isotopic compositions and elemental contents of the H, C, N, and O in 163 rice samples were analyzed. The samples were taken from three different farming countries; Japan (n = 103), United States of America (n = 30), and Australia (n = 21), in addition of Asian rice samples from Thailand (n = 2), Vietnam (n = 1), and China (n = 6) as comparison. They were mostly short grain samples known as "Koshihikari," with several samples of middle and long grains included. All samples were grown in the presence of either natural manure or artificial fertilizer. The climate of the rice farming environment was diverse, from arid to humid. Excluding deltaD data showing large uncertainty, according to the statistical analysis of the principal components based on the stable isotopic compositions such as delta(13)C, delta(15)N, and delta(18)O of rice samples, the Japanese rice samples were clearly distinctive from the Australian and the American rice samples. This fact may be explained by the regional differences in isotopic signatures of the climate, utilized nutrition, and/or quality of irrigation water among the farming countries. This statistical distinction could be one of the useful tools to extract the rice samples grown in Japan from those grown in the other countries.