Nawaz R.,Asian Institute of Technology |
Parkpian P.,Asian Institute of Technology |
Garivait H.,Environmental Research and Training Center |
Anurakpongsatorn P.,Kasetsart University |
And 2 more authors.
Communications in Soil Science and Plant Analysis | Year: 2012
The impacts of simulated acid rain on leachability of major plant nutrients, toxic element [aluminum (Al)], and acidity development in highly weathered tropical soils of Thailand were studied. Leaching experiments were conducted on soil columns with acidic solutions of pH 5.0, 4.0, 3.0, 2.0, and with water of pH 7.0 as a control treatment. Leaching losses of base cations from all soils increased with the decrease in pH associated with simulated acid rain (SAR) additions, and were found to be quite high under SAR with pH 2.0. The leaching removal of these cations was lesser at pH 3.0, 4.0, and 5.0 but greater than that in pH 7.0. The leaching of base cation from the soils depended not only on acid rain pH but also on soil properties, especially cation exchange capacity, soil texture, and initial base content. The significant losses of major plant nutrients [such as potassium (K+), calcium (Ca2+), and magnesium (Mg2+)] from the plant root zone over extended periods could cause nutrient imbalance and lower soil productivity. © 2012 Copyright Taylor and Francis Group, LLC.
PubMed | Kasetsart University and Environmental Research and Training Center
Type: Journal Article | Journal: Journal of agricultural and food chemistry | Year: 2016
A simple, sensitive, and high-throughput method was developed for the determination of six volatile phthalate esters-dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP)-in seafood samples by using monolith adsorbent in a capillary coupled to a gas chromatography-mass spectrometry (GC-MS) system. The freeze-dried samples were subjected to an ultrasonication with hexane, followed by vortex mixing. The liquid extract was quantitatively determined by a direct application to an online silica monolith capillary adsorbent coupled with a gas chromatograph with mass spectrometric detection. Method validation in seafood matrix gave recoveries of 72.8-85.4% and a detection limit of 6.8-10.0 ng g(-1) for bivalve samples. Reusability of the monolith capillary for trapping coextracted matrix was up to six times, allowing high-throughput analysis at the parts per billion level. When compared with the Food and Environment Research Agency (FERA) method, no significant difference in the result was observed, confirming the method was valid and applicable for the routine analysis of phthalates in seafood samples for food and environmental laboratories.
PubMed | Tokyo University of Technology, Ruhuna University, Environmental Research and Training Center, University of Tokyo and 3 more.
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2016
River water samples were taken from 32 locations around the basin of Chaophraya River and its four major tributaries in Thailand to investigate resistance ratios of Escherichia coli isolates to eight antibiotic agents of amoxicillin, sulfamethoxazole/trimethoprim, tetracycline, doxytetracycline, ciprofloxacin, levofloxacin, norfloxacin and ofloxacin. Principal component analysis was performed to characterize resistance patterns of the samples. Relevancy of the obtained principal components with urban land use and fecal contamination of the river were examined. The ratio of antibiotic-resistant bacteria is likely to increase when urban land use near the sampling site exceeds a certain ratio. The resistance ratio to fluoroquinolones tends to be high in a highly populated area. Meanwhile, no significant contribution of fecal contamination was found to increase the resistance ratio. These results suggest that an antibiotic-resistance ratio is dependent on conditions of local urbanization rather than the upstream conditions, and that the major sources of antibiotic-resistant bacteria in the Chaophraya River basin are possibly point sources located in the urban area which contains a high ratio of resistant bacteria.
Limjirakan S.,Chulalongkorn University |
Limsakul A.,Environmental Research and Training Center
Journal of the Meteorological Society of Japan | Year: 2012
Based on updated quality controlled daily records, extreme events were defined using temperature indices proposed by the Commission for Climatology/Climate Variability and Predictability project's Expert Team on Climate Change Detection, Monitoring and Indices, and temporal trends during the 1970-2009 period were examined in Thailand. Results revealed that Thailand has indeed experienced significant country-wide warming over the last four decades, and extreme events associated with both the cold and warm extremes of daily minimum and maximum temperature distributions have changed accordingly. Trends in temperature indices showed much spatial trend coherence and widespread significant warming, generally consistent with the regional evidence recently documented in other Asia-Pacific Network countries. Significant upward trends in temperature extreme indices were found in the annual number of warm nights and days, the annual occurrence of warm spells, tropical nights, summer days, and the highest and lowest values of daily minimum temperatures. In contrast, significant downward trends were observed in the annual number of cold nights and days, the annual occurrence of cold spells, diurnal temperature range and annual extreme temperature range. Changes in these temperature extreme indices were consistent with a significant shift in the temperature distribution toward warmer conditions over the recent decades. To address changes in Thailand's temperature more clearly, however, the plausible underlying mechanisms, including urbanization effects, need to be further studied. © 2012, Meteorological Society of Japan.
Limsakul A.,Environmental Research and Training Center |
Singhruck P.,Chulalongkorn University
Atmospheric Research | Year: 2016
Based on quality-controlled daily station data, long-term trends and variability of total and extreme precipitation indices during 1955-2014 were examined for Thailand. An analysis showed that while precipitation events have been less frequent across most of Thailand, they have become more intense. Moreover, the indices measuring the magnitude of intense precipitation events indicate a trend toward wetter conditions, with heavy precipitation contributing a greater fraction to annual totals. One consequence of this change is the increased frequency and severity of flash floods as recently evidenced in many parts of Thailand. On interannual-to-interdecadal time scales, significant relationships between variability of precipitation indices and the indices for the state of El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) were found. These results provide additional evidence that large-scale climate phenomena in the Pacific Ocean are remote drivers of variability in Thailand's total and extreme precipitation. Thailand tended to have greater amounts of precipitation and more extreme events during La Niña years and the PDO cool phase, and vice versa during El Niño years and the PDO warm phase. Another noteworthy finding is that in 2011 Thailand experienced extensive flooding in a year characterized by exceptionally extreme precipitation events. Our results are consistent with the regional studies for the Asia-Pacific Network. However, this study provides a more detailed picture of coherent trends at a station scale and documents changes that have occurred in the twenty-first century, both of which help to inform decisions concerning effective management strategies. © 2015 Elsevier B.V.
Kachenchart B.,Chulalongkorn University |
Jones D.L.,Bangor University |
Gajaseni N.,Chulalongkorn University |
Edwards-Jones G.,Bangor University |
Limsakul A.,Environmental Research and Training Center
Agriculture, Ecosystems and Environment | Year: 2012
An important ecological service provided by tropical riparian ecosystems is the mitigation of nutrient pollution (e.g. nitrate) from surrounding agricultural areas. However, a negative impact of this nutrient remediation may be that the ecozone also functions as a major emitter of nitrous oxide (N 2O). We hypothesized that the high inorganic nitrogen, organic carbon, and soil water content in tropical riparian ecosystems enhances N 2O production through rapid nitrification and denitrification processes. This study was therefore designed to quantify the variability in N 2O emissions in such an ecosystem in northern Thailand with specific emphasis on (1) different land uses (comparing replicate leguminous reforestation areas with conventional maize agriculture with high rates of nitrogen fertilizer addition), and (2) temporal aspects (comparing wet and dry seasons). Our aim was to quantify N 2O emissions and to identify the major drivers controlling these emissions. Using in situ closed chambers the annual average emissions of N 2O from the leguminous reforestation area (3.3kgN 2ONha -1 y -1) was significantly higher than agricultural areas with maize (2.2kgN 2ONha -1 y -1). The seasonal variation results indicated that the rate of N 2O flux in the wet season was higher than in the dry season. The variations of N 2O emission rates were strongly correlated with water filled pore space (WFPS), denitrification, and microbial biomass C, but not with nitrification. This study indicates that when inorganic N and soil organic C are sufficient, WFPS plays an important role in controlling N 2O emissions from denitrification. Comparatively, annual N 2O emissions from the tropical riparian reforestation were similar to that reported for temperate riparian forests and other ecosystems. Although the annual N 2O emissions from the maize agricultural area were comparable to other crops cultivated in riparian ecosystems, it was higher than the N 2O fluxes from crops grown in non-riparian zones. We conclude that agricultural lands located in tropical riparian zones do not represent a major hotspot of N 2O emissions and that this does not diminish the positive benefits they provide in relation to other aspects of ecosystem service provision. © 2012 Elsevier B.V..
Limsakul A.,Environmental Research and Training Center |
Limjirakan S.,Chulalongkorn University |
Suttamanuswong B.,Environmental Research and Training Center
EnvironmentAsia | Year: 2010
The Asian monsoon is an important component of the Earth's climate. Its associated rainfall variability is a crucial factor for Thailand's socio-economic development, water resources and agricultural management. An analysis shows that the Thailand rainfall annual cycle is in phase with the Indian summer monsoon (ISM) and the western North Pacific summer monsoon (WNPSM). On the basis of the Empirical Orthogonal Function (EOF) analysis, the dominant spatial-temporal interannual variability in summer monsoon rainfall (Jun.-Sep.) during 1975-2006 could be explained by the first two EOF modes, accounting for 34% of the total variance. The EOF1 was spatially dominated by strong positive signals in the central and east, whereas the EOF2 exhibited dipole variability. The coefficient time series of EOF1 significantly correlated positively with ISM index, but negatively with WNPSM index. The results suggest that summer monsoon rainfall in Thailand is higher (lower) than normal during the strengthening (weakening) of ISM. In contrast, rainfall in the north-east (central) is surplus (deficit) during the strengthening (weakening) of WNPSM. These findings imply that, on an interannual time scale, ISM and WNPSM exert their influence to a different extent on summer monsoon rainfall in Thailand. A clear picture of linking mechanisms and interactions with another climate mode in the Indo-Pacific sector needs to be understood. This knowledge is essential for effectively adapting to climate-related hazards and rainfall extremes and for better management of water resource and agriculture in Thailand, especially under current/future warming conditions.
Kitwattanavong M.,Chulalongkorn University |
Prueksasit T.,Chulalongkorn University |
Morknoy D.,Environmental Research and Training Center |
Tunsaringkarn T.,Chulalongkorn University |
Siriwong W.,Chulalongkorn University
Human and Ecological Risk Assessment | Year: 2013
The occupational health risk of petrol station workers from exposure to BTEX and carbonyl compounds via inhalation was estimated in the inner city of Bangkok. Personal sampling was performed within the workers' breathing zone using 2,4 dinitrophenylhydrazine cartridges and charcoal glass tubes connected to a personal air pump during eight working hours at six petrol stations. BTEX and carbonyl compounds were quantitatively analyzed by GC/FID and HPLC/UV, respectively. Of all detectable BTEX and carbonyl compounds, the levels of the four most prevalent compounds (benzene, ethylbenzene, formaldehyde, and acetaldehyde) were used to assess the lifetime cancer risk and 95% confidence interval of the risk levels were found to be totally higher than acceptable criteria for benzene (1.82 × 10-4-2.50 × 10-4), formaldehyde (7.81 × 10-6-1.04 × 10-5), ethylbenzene (4.11 × 10-6-5.52 × 10-6), and acetaldehyde (1.39 × 10-6-2.45 × 10-6). Thus, petrol station workers in the inner city of Bangkok have a potentially high cancer risk through inhalation exposure. With respect to the noncarcinogenic agents, toluene, m,p-xylene, o-xylene, and propionaldehyde, all non-cancer health risk were within hazard quotients of 1 and of acceptable risk. © 2013 Copyright Taylor and Francis Group, LLC.
Kwan C.S.,Tokyo University of Agriculture and Technology |
Kwan C.S.,University of the Philippines at Diliman |
Takada H.,Tokyo University of Agriculture and Technology |
Boonyatumanond R.,Environmental Research and Training Center |
And 6 more authors.
Science of the Total Environment | Year: 2014
Historical trends of the accumulation of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a typical tropical Asian environment were investigated using radio-dated sediment cores from Manila Bay, the Philippines and from the upper Gulf of Thailand. Vertical profiles indicated earlier usage of PCBs than of PBDEs which coincided with their industrial production. The increasing concentrations of total PBDEs and PCBs toward the surface suggested an increased consumption of PBDEs; and possible leakage of PCBs from old machineries into the aquatic environment in recent years. Current input of PCBs to the catchment of Manila Bay was supported by the analyses of air samples and plastic resin pellets. The vertical profiles of total PBDEs in the cores (i.e., rapidly increasing concentrations corresponding to the mid-1980s until mid-1990s, followed by a decrease until the early 2000s, and increasing again toward the surface) likely corresponded to the rapid economic growth in Asia in the 1990s, the Asian financial crisis in 1997, and the economic recovery since early 2000s. BDE-209 was predominant especially on the surface layers. BDEs 47 and 99 generally decreased toward the surface, reflecting the phase-out of the technical penta-PBDE products and the regulation by the Stockholm Convention in recent years. Increasing ratios of BDE-202/209, 206/209, 207/209 and decreasing % of BDE-209 down the core layers may provide evidence for the anaerobic debromination of BDE-209 in the sediment cores. Inventories in ng/cm2 of total PCBs were higher than total PBDEs (92 vs. 34 and 47 vs. 11 in the Philippines; 47 vs. 33 in Thailand). However, the doubling times indicated faster accumulation of total PBDEs (6-7years) and BDE-209 (6-7.5years) than of PCBs (8-11years). Furthermore, the temporal increase in BDE-209 was comparable to or faster than those reported in other water bodies around the world. © 2013 Elsevier B.V.
Tipmanee D.,Chulalongkorn University |
Deelaman W.,Environmental Research and Training Center |
Pongpiachan S.,National Institute of Development Administration |
Schwarzer K.,University of Kiel |
Sompongchaiyakul P.,Chulalongkorn University
Natural Hazards and Earth System Science | Year: 2012
In this study, we attempted to use PAHs as a chemical proxy to trace the transport of land-derived materials caused by the tsunami backwash to better understand how it may have affected the distribution of sedimentary deposition throughout the seabed of Khao Lak coastal areas. By analyzing the compositions of sedimentary PAHs in combination with application of the multivariate descriptive statistical techniques, PAHs were proven to be a promising chemical proxy to indicate the tsunami backwash in the study area. Their spatial distribution could indicate that the tsunami backwash plays an important role in transporting anthropogenic PAHs to the nearby coastal area as far as approximately 25 km from the shoreline. In addition, the results from diagnostic PAH isomer ratios suggested that road paving asphalt, originated from heavy erosion by the tsunami wave in front of Pakarang Cape, was among the identified sources of PAHs. Principle Component Analysis (PCA) results provided 2 estimated land-derived sources of PAHs, which were the road dust and oil burning sources. These estimated signature sources clearly support our hypothesis that PAHs were transported from the potential sources on land and deposited into the near-shore seabed during tsunami backwash. © 2012 Author(s).