Microplastic (MP) pollution threatens coastal ecosystems, yet hydrodynamic retention mechanisms often remain poorly constrained. This study investigates the spatial distribution, polymer composition, and hydrodynamic controls on microplastic accumulation in Ao Kung Krabaen, eastern Thailand, a shallow, mangrove-fringed system receiving both marine inflow and aquaculture effluent. Fifteen sediment samples were collected across four hydro-morphologically distinct zones: the Lagoon-Sea Interface (LSI), Inner Lagoon Area (ILA), Mangrove Transitional Zone (MTZ), and Sedimentation Canal (SC). The results show that MP concentrations range from 73 to 367 particles kg⁻1 dry weight (mean: 184 ± 74). Fragments (51

UNESCO World Heritage Sites in Kamphaeng Phet, Thailand, once part of the Sukhothai Kingdom, are built with laterite (e.g., temples, pagodas, and city walls). Four laterite deposits (Lan Dokmai Tok, Nong Pling, Phran Kratai, and Nong Hua Wua) have been found in the immediate vicinity and may have served as sources for construction materials. However, no studies have been conducted on this topic in the region. This study aims to analyze the geochemistry of laterite from four sites to explore and improve our understanding of their formation stages and processes. Field investigations identified various morphological types of nodular laterite, including vermiform, pisolitic, pisolith, and ferruginised. Darker-colored laterites (black, brown, and red) have greater relative hardness compared to their lighter-colored counterparts (pink, yellow, and white). Based on XRD and XRF analysis, the darker-colored laterites contain high concentrations of secondary iron minerals (hematite, goethite, and/or magnetite) and high iron oxide contents (>35 wt.%). In contrast, lighter-colored laterites predominantly comprise secondary clay minerals (kaolinite, montmorillonite, and/or muscovite) and exhibit lower iron oxide contents. Based on SiO2, Al2O3 and Fe2O3 concentrations, these laterites have undergone moderate to strong laterization processes. The presence of gabbro core stones and minerals such as hercynite and fayalite in laterite samples from Lan Dokmai Tok suggests that gabbro is the parent rock. In a tropical climate, the parent rock undergoes weathering processes for a long period, resulting in secondary clay and iron minerals. The concentration of the iron minerals has been controlled by different conditions such as water table levels and surrounding geological features (e.g., bedrock type, or faults). The geomorphological setting and thickness of all laterite sites indicate in situ formation. All tested laterites are suitable building materials and were likely integral for constructing historical sites. These findings can provide valuable information for archeological research in the region.

Beach ridges are depositional landforms that provide information related to coastal evolution, storm activity and sea-level variations. However, beach ridges are sometimes modified by aeolian processes, storm washover and/or human activity. Therefore, systematic investigations are required to use beach ridges as an archive of palaeoenvironmental conditions and sea-level changes. In this study, a multidisciplinary approach involving ground-penetrating radar, sedimentological analysis and optically stimulated luminescence as well as radiocarbon dating was used to reconstruct sedimentary processes and past sea-level changes that formed beach ridges in the coastal zone of Nakhon Si Thammarat province, Lower Gulf of Thailand. Ground-penetrating radar data reveal evidence of beach progradation coupled with the presence of beach scarps and washover deposits. This implies that the formation of the beach ridges occurred under swash processes on the beachface and was later punctuated by erosion during storm surges, leading to the deposition of washover sediments. During a storm, elevated seawater transported moderately to poorly sorted medium-to-coarse sand onto a higher position along the beach profile, resulting in an elevation of the beach ridge of up to 4.6 m above mean sea-level. In addition, aeolian processes contributed to vertical accretion by depositing well-sorted fine sand on the surface of the beach ridges. The dating results indicate that the formation of the beach ridges occurred approximately between 8.6 ka and 6.1 ka and can be attributed to an upper sea-level limit of 1.8 to 2.3 m above present-day mean sea level. Both allogenic (e.g. sea-level and climate variability) and autogenic (e.g. sediment supply and wave action) factors play crucial roles in the formation and evolution of beach ridges. Therefore, the multidisciplinary approach of this study enhances the understanding of these composite depositional processes and improves palaeoenvironmental reconstructions derived from beach ridges.

Calcium carbonate (CaCO3) is an essential raw material in the manufacture of goods and industrial products like cement, rubber, paper, paints, food, and medicines. For this compound to be economically valuable, however, its quality needs to meet the standard market requirements. Among the various impurities found in natural CaCO3-bearing ores, iron (Fe) is one of the most problematic. In this study, the upgrading of low-grade CaCO3 from a processing plant in Thailand by magnetic separation was investigated. Detailed characterization of the low-grade material was also carried out to identify the solid-phase partitioning of Fe. The results showed that Fe was mainly associated with magnetite and pyrrhotite in the ore, and during processing, additional Fe was introduced from the ball milling process. To improve the quality of this low-grade CaCO3, the effects of magnetic field intensity, feed rate, and repetition on the induce roll magnetic separation were investigated. Based on the results, higher magnetic field intensity, lower feed rate, and more repetition are required for the upgrading of low-grade CaCO3.

Beach ridges are depositional features that allow reconstruction of past sea-level variations, sediment dynamics, and storm activity. However, there are still very few systematic studies focusing on beach ridges available from the Gulf of Thailand. Along the east coast, satellite images provide evidence of beach ridges in the Chanthaburi Province, extending as far as 6 km inland, oriented parallel to the current coastline. These can be divided into a set of landward ridges (5.3–6.0 km inland) and seaward ridges (0.4–1.8 km inland) that are separated by an arm of the Chanthaburi estuary. Optically stimulated luminescence dating of 26 sand samples from 12 pits of ridge profiles suggests that the landward set of beach ridges formed ca. 3500 yr ago, while the seaward set of ridges formed between ca. 2100–1200 years ago, which also includes the modern active beach. It appears that the landward set of beach ridges developed during a period of relatively stable sea level followed by a rapid regression presently occupied by the arm of the Chanthaburi estuary. The seaward set of beach ridges apparently reflects a millennium of slowly retreating coastline until the modern beach ridge formed.

Plastic debris is thought to be widespread in freshwater ecosystems globally 1 . However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging 2 , 3 . Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 μm) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris 4 . Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services.

Due to the effects of an anthropogenic global warming, the concern about the emissions of carbon dioxide (CO2) into the environment has increased in various industries like petroleum industry. Currently, the use of the geological storage techniques, such as carbon capture and sequestration (CCS), is the most promising way to mitigate these emissions. The objective of this study on a numerical simulation is to investigate CO2 onshore geological storage in the depleted oilfields in the North of Thailand. The geological modelling is a critical step in proving the suitability of a geologic formation for a CCS project. The simulations of the pressure build-up, CO2 plume movement and the amount of CO2 stored are the main points of this research. The development of the 3D reservoir model is performed by means of CMG-GEM, and CMG-WINPROP. This study performs how CO2 sequestration is injected with the flow rate of 1000–4000 tons/day into a reservoir with a depth of 2120-2161 m. The result indicates that CO2 moves up to the top formation. Moreover, 0.583 Mt of CO2 can be stored into the reservoir. This presents the preliminary study for the CO2 sequestration in Northern Thailand, which aids in the next phase of CCS projects in Thailand.

The main carbon dioxide (CO 2 ) emissions in Thailand come from the energy sector. Gas-based power plants, including natural gas and biogas, are CO 2 point sources, and are mostly located in the Khorat Plateau. Geological CO 2 storage is an important element in the effort to reduce CO 2 emissions from CO 2 point sources. This study is a preliminary assessment of the geological CO 2 storage potential of the onshore Khorat Plateau. A potential geological formation is screened and ranked in terms of its suitability as a CO 2 storage site (storage optimization, risk minimization and feasibility). The results of this screening and ranking indicate that, among the tested sites in this study, the Khorat Permian carbonate is the most suitable for geological CO 2 storage, followed by the Khorat Group sandstone, and Khorat evaporite. However, the Khorat Cenozoic basalts are not suitable for geological CO 2 storage in the Khorat Plateau. The results from this study should advance the understanding of petroleum exploration and carbon capture and storage technology in Thailand, especially in the Khorat area. However, it should be noted that more subsurface studies are needed, and more criteria should be included in the future to improve the reliability of the assessment of geological CO 2 storage potential in the Khorat Plateau.

Soundless Chemical Demolition Agents (SCDAs) are an environmentally friendly and safer alternative to traditional rock fragmentation methods. Admixtures are used to change the rheological properties and performance of SCDAs. This study aimed to investigate the effect of various concentrations of chemical accelerators (chloride salts) and viscosity enhancing agents (VEAs: Xanthan gum, Guar gum, and Gellan gum) on the fracture onset compared to an unmodified SCDA (BRISTAR 100®). All experiments were conducted on Portland Type 1 (OPC 1) cement blocks. The flowability of the mixtures was determined by mini-slump tests. Results show that 4wt% MgCl2 and 3wt% CaCl2 have accelerated the fracture onset by 47.4% and 61.2%, respectively. VEAs have a decelerating effect, which is mitigated by the addition of the aforementioned chloride salts. Combining 4wt% MgCl2 with 0.2wt% Xanthan gum reduced the fracture onset time by 66.8%. A cost analysis shows that the initial price of the SCDA mainly determines a potential cost reduction by using admixtures. For a low-cost SCDA, the focus is likely to shift to saving time. This study can serve as a basis for future studies to further improve performance and cost as well as diversify the range of applications for SCDAs.

The Cenomanian (Upper Cretaceous) Maha Sarakham Formation of the Khorat Basin, northeastern Thailand consists of three evaporite units (Lower, Middle and Upper Salt) interbedded with clastic sediments and exhibits abundant deposits of potash. Although numerous studies have been carried out on the Khorat potash deposit, results are still equivocal with regard to the origin of the rock salt, whether it was marine or non-marine (hydrothermal and/or mixed fluids). The purpose of this study is to examine the origin of rock salt based on elemental compositions and boron isotope analyses in the southwestern part of the Khorat Basin. A stratigraphic correlation of five boreholes (K-201– 205) located in Bamnet Narong and Chaturat districts, Chaiyaphum province, Thailand, revealed a salt dome structure. The elemental composition and δ11B values in the longest borehole K-203 indicate a precipitation of halite and carnallite from seawater. Rare earth elements (REE) of claystone and siltstone from five boreholes (K-201– 205) are comparable to the REE of sandstone from the Simao Basin in China, which suggest a similar provenance. Stratigraphic comparisons and geochemical signatures are important for a better understanding of the recharge models of paleoseawater. In agreement with some previous studies, we conclude that the Cenomanian evaporites within the Khorat Basin are marine deposits.

Salt caverns are an adequate solution for the sequestration of CO2 (large capacity, safety and long-term operation). The large rock salt deposits of the Maha Sarakham Formation represent a very promising location. Designing salt caverns is still a complex issue. In this paper, the stability of typical cavern shapes (spherical, cylindrical, teardrop, bulb, and pear) was evaluated based on displacement, von Mises stress, safety factor, and volume change. The analysis aimed to find the optimal cavern shape for salt deposits at Ban Nong Plue, Borabue district, Maha Sarakham province, northeast Thailand. The Finite Element simulations investigating the cavern stability are carried out for a time span of 600 years (> 500 years is considered permanent storage). The bulb-shaped cavern yielded the best results, indicating that it constitutes the optimal shape in the given geological conditions. The stability of all analyzed caverns showed a dependence on the operating stage. Each stability factor exhibited large differences between the periods of cavern construction/brine discharge and pre-pressurization by CO2 injection. A lower cavern pressure negatively affected the evaluated factors. The results can be useful in planning future cavern fields for CO2 storage (and other gases) in salt deposits.

Microplastic pollution is one of the most significant global environmental concerns. This study represents a first attempt to establish connections between the concentration of microplastics and both ocean surface circulation direction and land-based sources along the western Gulf of Thailand. Microplastics at the high-tide line from 25 beaches in 5 provinces were quantified. Observed amounts range from 20 to 273 (max. 5741) pieces/kg. Sheets were the most common shape and black the most common color of microplastics. Our study showed a significant, positive correlation between the number of microplastics and land-based sources (e.g., aquatic industries). While human activities were the dominant factor affecting microplastic concentrations, the newly designed surface circulation direction (SCD) index reflected relative changes in microplastic amounts. Our study identified several locations with substantial microplastic pollution which require a proper management system with appropriate laws and regulations, and a public awareness campaign about effects of microplastics on ecosystems.

Mainland Southeast Asia is located on the route of moisture transport of the Indian summer monsoon where hydroclimate records from speleothems have rarely been investigated. Here we present a new multi-proxy data set (δ18O, δ13C, trace elements and grayscale values) of stalagmite KPC1 from Khao Prae cave in western Thailand spanning from approximately 500 CE to 1900 CE. Our multi-proxy data reveal high variability between wet and dry periods during 500-850 CE and 1150-1350 CE, a stable condition between 850-1150 CE, and an overall trend towards dry conditions since 1350 CE. The δ13C, trace elements and grayscale values suggest centennial-scale fluctuations driven by local hydrological process at the cave site. In contrast, variations in stalagmite δ18O reflect integrated changes in rainfall amount from the Indian summer monsoon, supported by two-year monitoring rainfall data. In comparison with other Asian Monsoon records for the last millennia, the KPC1 record shows similarity with speleothem δ18O records from India, as well as lakes and tree-ring data from mainland Southeast Asia but diverges from records from equatorial regions and the western Pacific. We conclude that hydroclimate variability in the western side of Mainland Southeast Asia is mainly driven by changes in moisture transport from the Indian summer monsoon and modulated by expansion and contraction of the Intertropical convergent zone (ITCZ). However, Pacific Walker circulation (PWC) may have been the overriding control on precipitation on the eastern sides of Mainland Southeast Asia located closely to the western Pacific.

At present a total of 118 hot springs are distributed throughout Thailand. Several studies with a focus on high-temperature hot springs related to geothermal resources were conducted in the northern and southern part of the country. Geochemical data, however; especially isotopes of medium-low temperature hot springs are still scarce. In this study, we aim to investigate the geochemical composition of hot spring waters from western Thailand. The examination of elemental compositions and stable isotopes (δ18O, δD) of 3 hot springs; Hin Dad, Bor Klueng and Baan Samorthong (surface water temperatures of 40–50 °C), contributes to a better understanding of reservoir temperatures and recharge. The results from elemental compositions show that the chemical type of the hot spring waters from Baan Samorthong and Bor Klueng are alkaline-carbonate, while the hot spring from Hin Dad is a calcium-carbonate type with a high amount of sulfate related to bedrock. Based on the silica geothermometer approach, reservoir temperatures are calculated to be between 65–90 °C. The stable isotopes δD and δ18O of all hot spring waters suggest a recharge with meteoric waters as well as mixing with groundwater. The three hot springs in this study are well-known for public water recreation and health therapy. Regarding toxic elements, Baan Samorthong hot spring has high fluoride (F-) (14.84 mg L-1); while Hin Dad hot spring shows concentrations of Pb2+ (0.07 mg L-1) and Bor Klueng of Pb2+ (0.02 mg L-1), As5+ (0.01 mg L-1) and F- (4.35 mg L-1) which are above drinking water limits and might lead to health problems. Therefore, we recommend not to drink the water from the hot springs. In conclusion, a better understanding of geochemical data is beneficial for the sustainable development of medium-low temperature hot springs in Thailand.

Several studies have shown the ubiquitousness of microplastics across ecosystems worldwide including significant amounts in beach sand. In Thailand, however, there is a lack of studies about the microplastic pollution of beaches. This study aimed to quantify microplastics at the high-tide line of 21 beaches along the eastern Gulf of Thailand. Observed amounts ranged from 420 to >200,000 counts/kg. Anthropogenic and environmental factors affect distribution and amount of microplastics. Tide-dominated beaches and beach sections protected by beachrocks exhibit higher microplastic amounts due to lesser hydrodynamics. While human activities have a visible impact, in some cases environmental factors seem to predominate. Despite effective protection efforts led by the government and NGOs, our study shows that the substantial microplastic pollution of beach sand requires a proper management system with appropriate laws and regulations, and a public awareness campaign to reduce effects of microplastics on organisms and their ecosystems.

Concerns about heavy metal and metalloid contamination from mine dumps is one of the most intensively discussed issues in society, politics, and academia, because of the levels of pollution, and its toxic properties. During the Middle Ages the Black Forest was one of the most successful mining areas in Southwestern Germany. Historical records show that Sulzburg was a mining town in the Black Forest since the 10th century, but was abandoned in the 19th century. Nowadays this town is considered as an important recreation area in the country. Therefore, soil and water quality and any contamination are of great concern. The purpose of this research was to understand the weathering process and environmental impact of heavy metals and metalloids from the old antimony (Sb) mine sites in Sulzburg. In this study, we examined the mineralogy and whole-rock chemistry and performed soil sequential extraction and water chemical analysis around mine sites. The results show that the Sb deposits in Sulzburg contain mixtures of antimony-lead-bearing sulfides and sulfosalts in hydrothermal quartz veins. The primary ore stibnite (Sb2S3) and boulangerite (Pb5Sb4S11) occur associated with pyrite, arsenopyrite, and sphalerite. The whole-rock chemistry of Sb-Mine Sulzburg is characterized by considerable Sb2O3 (4-25 %) and PbO contents (2-7 %). This agrees with the chemical composition of Sb minerals. Based on soil sequential extraction, toxic elements (Sb, Pb, As) mostly remain in the residual fraction. Comparing the water analysis at and around Sb-mine Sulzburg, Sb concentrations are lower than those of As and Pb for all water samples. This is possible due to the strong affinity of Sb to Fe-oxides-hydroxides and amorphous material and a lower mobi-lity, from the source into water. Based on these findings, we argue that sources of toxic elements and weathering process in Sulzburg are important from the ecotoxicity perspective. Changes in oxidizing or reducing conditions can lead to release and mobilization of Sb, As, and Pb into the environment.

Locating suitable caves and stalagmites for palaeoenvironmental and palaeoclimatic studies can be challenging. Isotopic geochemical analyses, albeit commonly performed for palaeoclimatic reconstruction, are also time consuming and costly. Therefore, petrographic and non‐destructive morphological studies on speleothems are desirable to facilitate sample selection for further analysis. In this study, 20 caves were surveyed in Ban Rai district, Uthai Thani province in western Thailand. After external physical observations in the field, three stalagmite samples were collected from Tham Nam Cave to test their potential for palaeoclimatic research. Firstly, the stalagmites were scanned by X‐ray computed tomography ( CT scanning) and subsequently the CT images were compared with petrographic inspections. Columnar fabrics show the highest density, whereas closed and open dendritic fabrics have medium and the lowest densities, respectively. Layers near the top and bottom of the three stalagmites were dated by U‐Th mass spectrometric techniques. All three samples were deposited between c. 87 and c. 105 ka ago; therefore, they are probably the oldest stalagmites that have been reported so far from mainland Southeast Asia. However, their physical features indicate that all the samples have suffered from postdepositional dissolution, and are unlikely to be suitable for palaeoclimatic research. The internal dissolution feature of stalagmites, however, cannot be identified by visual inspection of uncut samples. We hereby argue that CT images are useful to characterize stalagmite petrography, in particular fabric, porosity and density. Such features can be used to select the ideal plane of a stalagmite for sectioning, to maximize the chances of robust climatic reconstruction.

The detailed documentation of joint systems and their spatial variability are crucial for the optimal exploitation of fractured reservoirs. The extrapolation of well data up to reservoir scale is complex. This study investigates the potential of geomechan