Seasonal variation in water column conditions in the upper Gulf of Thailand     

Anukul Buranapratheprat  Tetsuo Yanagi  Satsuki Matsumura   《Continental Shelf Research》2008,28(17):2509-2522

Seasonal variation in water column conditions in the upper Gulf of Thailand (UGoT) was analyzed by considering four major factors including surface heat flux, freshwater discharge, tidal and wind stirrings. The coincidence of surface heat loss, low river discharge and strong wind resulted in vertical well-mixing in December. Strong stratification developed in September and October due to large river discharge and moderate heat flux. Strong surface heating in April and May has a potential to generate strong stratification, although not as large as that in September and October due to low river discharge. Although no factors are prominent during January and March, and June and August, weak to moderate stratification results, because the influences of river discharge and surface heating are still larger than those of tidal and wind stirrings. The results of water column analysis based on monthly average data agree well with analyses derived from cruise data in the same months. Most analytical results correspond to the distributions of temperature and salinity from field observations. Disagreement, however, was found in December 2003 (cruise CU-2) when stratification in some small regions occurs in the distribution of water properties, but the water column analysis suggests vertical well-mixing. This phenomenon is triggered by non-uniform distribution of freshwater over UGoT, which is related to river discharge, monsoonal wind and current. Compared to a previous study regarding surface chlorophyll dynamics, water column conditions may be used to explain the occurrence of phytoplankton bloom in this region.  相似文献   

Revisiting frontiers as transitional spaces in Thailand     

PHILIP HIRSCH 《The Geographical journal》2009,175(2):124-132

This paper explores the notion of frontiers as 'in-between' spaces that define particular transitions. Three contexts of frontier and their rapidly changing nature form the basis of the analysis. Agricultural frontiers (typically between farmland and forest) are defined by new relations of production and interplays between conservation, shifting modes of agriculture and natural resource use and management. Peri-urban frontiers (between countryside and city) are taken beyond their desakota/chaan-meuang locations to a more generic interplay between urbanity and rurality in defining livelihood and identity. National frontiers (between nation states with sharply different political and economic conditions) are transcended from above in the form of new regionalisms, and, from below, in migrations and other transboundary influences and flows. The paper proposes the frontier as both a spatial and temporal heuristic for understanding development and associated societal transitions in Thailand.  相似文献   

Sourcing Thai geography literature for ASEAN and international education     

Steven Andrew Martin  Raymond James Ritchie 《Singapore journal of tropical geography》2020,41(1):61-85

This study surveys the available English-language literature and learning resources covering the field of Thai geography, and provides historical review of Thai geography education and an inventory of relevant, accessible materials for ASEAN and international undergraduate students, educators and researchers. We note that the discipline and context of Thai geography has shifted toward new technologies, particularly geographic information systems, and this has left a void in practical and accessible text for high school and undergraduate students in gaining broad and traditional knowledge of the field. Our study finds that the accessibility of introductory English-language texts on Thai geography is limited, and that existing texts appear mainly in the grey literature or widely dispersed across various disciplines of study. The paper provides a platform to help future researchers and to facilitate future production of English-language textbooks and other study materials in the field of Thai geography.  相似文献   

Soldier crab (Dotilla myctiroides) distribution,food resources and subsequent role in organic matter fate in Ao Tang Khen,Phuket, Thailand     

Kimberly K. Takagi  Phaothep Cherdsukjai  Izumi Mimura  Yuka Yano  Kanjana Adulyanukosol  Makoto Tsuchiya 《Estuarine, Coastal and Shelf Science》2010

This study aimed to elucidate Dotilla myctiroides (H. Milne-Edwards) food resources and how the soldier crab influences the organic matter composition on the intertidal flat. A preliminary assessment of D. myctiroides size, sex, and population distribution was conducted to clarify the characteristics of the inhabiting population. Overall, D. myctiroides size and abundance was normal across the tidal flat area. Comparison of different sediment types from the soldier crab habitat (surface sediments, igloos, burrow lining, burrow pellets, feeding pellets, and feces) using the fatty acid (FA) analysis technique revealed D. myctiroides removes organic matter via the significantly lower contributions of polyunsaturated FAs, essential FAs, and dinoflagellates in the feeding pellets. Dotilla myctiroides tissue analysis of the hepatopancreas and hindgut in individuals that had been starved for 24 h confirmed not only the consumption of dinoflagellates, but diatoms and macroalgae as well. In addition, the FA metabolism within the digestive system implied the ability of the soldier crab to synthesize highly unsaturated FAs (HUFAs) such as 20:4n–6, 20:5n–3 and 22:6n–3.  相似文献   

The impact of artisanal fishing on coral reef fish health in Hat Thai Mueang,Phang-nga Province,Southern Thailand     

Estelle Jones  Tim Gray  Chanin Umponstira 《Marine Policy》2009

This study investigates whether there has been a decline in fish stocks of a coral reef in Thailand, and if so, whether that decline is due to small-scale fishing. The research methods used included fish sampling by UVC, interviews and questionnaires with key informants and artisanal fishers. The results confirmed that there has been a decline in piscivores and carnivores (though not herbivores), and the main perceived threat came not from artisanal but from commercial fishing. Recommendations are to replace the largely unrestricted fishery with a more regulated regime backed by effective enforcement.  相似文献   

Monitoring of coral communities in the inner Gulf of Thailand influenced by the elevated seawater temperature and flooding   总被引：1，自引：0，他引：1  

PENGSAKUN Sittiporn  YEEMIN Thamasak  SUTTHACHEEP Makamas  SAMSUVAN Watchar  KLINTHONG Wanlay  CHAMCHOY Charernmee 《海洋学报(英文版)》2019,38(1):102-111

There were two severe coral bleaching events at Ko Khang Khao, the inner Gulf of Thailand, occurred during the prolonged period of the elevated sea surface temperature (SST) in 2010 and low salinity as well as turbidity due to heavy flooding in 2011. The bleaching index (BI) and mortality index (MI) are calculated to compare the susceptibilities of coral species in the two bleaching events. The BI and MI vary significantly among the study sites and bleaching events. The most susceptible corals during both bleaching events are Acropora millepora, Pocillopora damicornis and Pavona decussate, while the most resistant species were Galaxea fascicularis, Fungia fungites, Pavona frondifera, Oulastrea crispate, and Symphyllia recta. The corals Favia favus, Goniopora columna, Platygyra pini, Symphyllia agaricia were relatively more tolerant to high SST but they are relatively more susceptible to low salinity. Coral bleaching is a phenomenon that the dissociation stress of the symbiotic relationship between zooxanthellae and their cnidarian host results in the reduction in photosynthetic pigment concentration. Among stressors, both prolonged exposure of high SST and low salinity, above and below their thresholds, respectively. The long-term resilience of coral communities at Ko Khang Khao and other coral communities close to the mouth of large rivers may depend on the frequency and duration of the exposure on the elevated SST due to atmospheric heating and low salinity due to river flooding.  相似文献   

Mainstreaming climate change adaptation into inland aquaculture policies in Thailand     

Anuwat Uppanunchai  Chanagun Chitmanat 《Climate Policy》2018,18(1):86-98

While there have been many pilot projects on adaptation undertaken in the fisheries and aquaculture sector, state policies are only just beginning to address let alone refer to climate change. This study explores the climate-related content, climate sensitivities, and opportunities to incorporate climate change concerns in a set of aquaculture policies by the government of Thailand. The analysis is based on content analysis of policy documents and in-depth interviews with 14 officials that had roles in the design or implementation of 8 Department of Fisheries policies. The Aquaculture Master Plan 2011–2016 and the now abandoned Tilapia Strategy refer directly to climate variability or change. The Master Plan also suggests measures or strategies, such as investment in research, and the transfer of technologies, which would be helpful to sustainability and adaptation. Other policies suggest, or at the very least include, practices which could contribute to strengthening management of climate-related risks, for example: a registration policy included provisions for compensation; extension programme policy recognizes the importance of extreme events; and a standards policy gives guidance on site selection and water management. Most existing aquaculture policies appear to be sensitive to the impacts of climate change; for instance, the zoning policy is sensitive to spatial shifts in climate. Stakeholders had ideas on how policies could be made more robust; in the case of zoning, by periodically reviewing boundaries and adjusting them as necessary.

POLICY RELEVANCE

This study is one of the first evaluations of the coverage and sensitivity of aquaculture policies to climate change. It shows that while existing policies in Thailand are beginning to refer explicitly to climate change, they do not yet include much in the way of adaptation responses, underlining the need for identifying entry points as has been done in this analysis. Further mainstreaming is one option; another possibility is to adopt a more segregated approach, at least initially, and to collect various policy ideas under a new strategic policy for the aquaculture sector as a whole.  相似文献   

Truncated flame structures within a deposit of the Indian Ocean Tsunami: evidence of syn‐sedimentary deformation     

DAN MATSUMOTO  HAJIME NARUSE  SHIGEHIRO FUJINO  APICHART SURPHAWAJRUKSAKUL  THANAWAT JARUPONGSAKUL  NORIHIKO SAKAKURA  MASAFUMI MURAYAMA 《Sedimentology》2008,55(6):1559-1570

This study reveals the three‐dimensional morphology and syn‐sedimentary formation processes of a deformation structure termed ‘truncated flame structures’ which is found in a terrestrial tsunami deposit in southern Thailand that formed during the 2004 Indian Ocean Tsunami. The structure was found at the boundary between a lower fine‐grained layer and an upper coarse‐grained layer that are related to two runup events. In order to confirm the morphology of the structure, the authors excavated two trenches and an opencast pit. When viewed in a cross‐section oriented parallel to the direction of the runup current, the deformed boundary has an irregularly bulging profile, similar to that observed in flame structures. The protruding structures are inclined towards the downstream direction of the runup current, and are truncated horizontally along their upper surface by parallel laminations in the overlying layer. When viewed in a cross‐section oriented perpendicular to the current direction, it appears that parts of the upper layer descend into the lower layer as lobate masses. In places, these masses are completely detached from the main part of the upper layer, forming circular or elliptical shapes. The contact between the lower layer and the main part of the upper layer is a planar truncation surface. Opencast excavation of the contact surface revealed that the deformed structures have flat, sinuous horseshoe crests that open in a downstream direction. It is possible for the runup current to generate shear stress such that it deforms the boundary into a truncated flame structure. Moreover, the observations made in this study indicate the syn‐sedimentary development of the structure: deformation and truncation occurred simultaneously in association with the runup current that formed the upper layer. Truncated flame structures can be used as a criterion in identifying the syn‐sedimentary deformation of substrate: the structures are indicative of unidirectional flow with sufficiently high shear velocity to deform unconsolidated substrate. As in the present case, the truncated flame structures may be characteristic of tsunami events that involve strong unidirectional currents on land due to the extraordinarily long wave period of tsunamis, rather than other events such as storm surges or flooding.  相似文献   

Arsenic contamination in surface drainage and groundwater in part of the southeast Asian tin belt,Nakhon Si Thammarat Province,southern Thailand   总被引：2，自引：0，他引：2  

M. Williams  F. Fordyce  A. Paijitprapapon  P. Charoenchaisri 《Environmental Geology》1996,27(1):16-33

The occurrence of human health problems resulting from arsenic contamination of domestic water supplies in Ron Phibun District, Nakhon Si Thammarat Province, southern Thailand was first recognized in 1987. The area has an extensive history of bedrock and alluvial mining, the waste from which is typically rich in arsenopyrite and related alteration products. In 1994 a collaborative study was instigated involving Thai and British government authorities to establish the distribution and geochemical form of As in surface drainage and aquifer systems in the affected area, the probable sources of As contamination, and the potential for problem alleviation. Hydrochemical analyses of surface- and groundwaters have confirmed the presence of dissolved As at concentrations exceeding WHO potable water guidelines by up to a factor of 500. Contamination of the shallow alluvial aquifer system is systematically more severe than the underlying carbonate-hosted aquifer. Deep boreholes may therefore provide the best available potable water source for the local population. The presence of up to 39% of total As as arsenite (H₃AsO₃) within the carbonate aquifer may, however, constitute a hidden toxicological risk, not evident in the shallow groundwater (in which arsenate species account for > 95% of total As). Mineralogical investigations of As-rich tailings and flotation wastes were undertaken to evaluate their likely impact on water quality. The results indicate that although some flotation wastes contain up to 30% As, the rate of leaching is extremely low. Consequently the As loading of drainage emanating from such waste is below the subregional average. Analyses of the silty alluvium that covers much of the central sector of the study area have highlighted As concentrations of up to 5000 mg kg^–1, probably carried by disseminated arsenopyrite. Following sulfide dissolution, the mobility of As in this material may be high (with resultant contamination of shallow groundwater) due to the low Fe content of the soil. On the basis of the data acquired, a range of pollution mitigation schemes are currently under investigation including Fe supplementation of alluvium and microbial degradation of disseminated arsenopyrite.  相似文献   

Trace elements and mineral chemistry of silicified wood from Thailand: colours and elemental distribution     

S. Saminpanya 《Australian Journal of Earth Sciences》2016,63(7):873-884

Thai silicified woods were examined using electron probe microanalysis, yielding chemical data that characterised the samples into two groups: low and high silica contents (82—94 wt% and 94—98 wt%). The elements analysed in order of abundance include Si > Fe > Ca > Na > Al > Ti > K > Mg > Mn > Zr. Iron plays a major role in the colour range (red, orange, yellow, brown, grey and black) of the samples. Calcium is associated with Fe in the darker colours of the wood. Pseudo-crystallochemistry has been used for the substitution of trace elements for Si⁴⁺ in silica polymorphs. The atomic channels that run parallel to the c-axis of silica polymorphs or lattice defects, or even the charge balance for trivalent-ion substitution for Si⁴⁺, can accommodate monovalent ions (K⁺ and Na⁺). Vacant and atomic cavities, which are charged balanced by trivalent ions [Al³⁺ or Fe³⁺ substituting for Si⁴⁺], are commonly occupied by divalent ions (Ca²⁺, Mg²⁺ and Mn²⁺). Quadrivalent ions, Ti⁴⁺ and Zr⁴⁺ are non-structurally incorporated but form clusters of mineral inclusions in the samples. Several other trace-element contents are also in the form of mineral/fluid inclusions hosted in the woods.  相似文献