Effects of Photosynthetically Active Radiation and Air Temperature on CO_2 Uptake of Pterocarpus macrocarpus in the Open Field

Since trees and plants can absorb CO2, forests are widely regarded as a carbon sink that may control the amount of CO2 in the atmosphere. The CO2 uptake rate of plants is affected by the plant species and environmental conditions such as photosynthetically active radiation (PAR), temperature, water and nutrient contents. PAR is the most immediate environmental control on photosynthesis while air temperature affects both photorespiration and dark respiration. In the natural condition, PAR and temperature play an important role in net CO2 uptake. The effects of PAR and air temperature on the CO2 uptake of Pterocarpus macrocarpus grown in a natural habitat were studied in the present work. Due to many uncontrollable factors, a simple rectangular hyperbola could not represent the measured data. The data were divided into groups of 2oC intervals; CO2 uptake in each group may then be related to PAR by a rectangular hyperbola function. Using the obtained functions, the effect of PAR was removed from the original data. The PAR-independent CO2 uptake was then related to air temperature. Finally, the effects of PAR (I) and air temperature (Ta) on the CO2 uptake rate (A) were combined as: (-0.0575Ta2+2.6691Ta-23.264)I A= ——————————————— (-0.00766Ta2+0.40666Ta-3.99924) (-4.8794Ta2+227.13Ta-2456.9)+I

Simulation of Seasonal Circulations and Thermohaline Variabilities in the Gulf of Thailand

Based on the Princeton Ocean Model （POM）, the seasonal thermohaline feature and the ocean circulation in the Gulf of Thailand （GOT）, situated between 6°N to 14°N latitude and 99°E to 105°E longitude, were studied numerically with 37 × 97 orthogonal curvilinear grid and 10 vertical sigma levels conforming to a realistic bottom topography. A spin-up phase of the first model run was executed using wind stress calculated from climatological monthly mean wind, restoring-type surface heat and salt, and climatological monthly mean fresh water flux data. In this paper, the temperature and salinity fields taken from Levitus94 data sets and the calculated temperature and salinity from the model run for 12-month mean and for each season are presented where the winter, summer, rainy, and end of the rainy seasons of Thailand are represented by the months January, April, July, and October, respectively. The simulated circulations are also described. The results show that the temperature in the GoT is warmer than the temperature of the other parts connected to the South China Sea （SCS）. At any depth of inflow from SCS into the GoT, the salinity is high, but in the outflow from the GoT at the surface, the salinity is low. The strong circulations are clockwise during summer and the rainy seasons of Thailand, which are the East Asian monsoon periods, northeasterly and southwesterly during summer. They occur near Pattani and Narathiwat provinces during summer and in the central GoT during the rainy seasons. Sensitivity experiments were designed to investigate the effects of wind forcing and open boundary conditions. Wind forcing is shown to be the important factor for generating the circulation in the GoT. The lateral velocity at the open boundaries is of considerable importance to current circulation for the rainy and end of the rainy seasons, with insignificant effect for the winter and summer seasons of Thailand.

Google Earth Engine Based Three Decadal Landsat Imagery Analysis for Mapping of Mangrove Forests and Its Surroundings in the Trat Province of Thailand

Monitoring and understanding the changes in mangrove ecosystems and their surroundings are required to determine how mangrove ecosystems are constantly changing while influenced by anthropogenic, and natural drivers. Cosistency in high spatial resolution (30 m) satellite and high performance computing facilities are limiting factors to the process, with storage and analysis requirements. With this, we present the Google Earth Engine (GEE) based approach for long term mapping of mangrove forests and their surroundings. In this study, we used a GEE based approach: 1) to create atmospheric contamination free data from 1987-2017 from different Landsat satellite imagery;and 2) evaluating the random forest classifier and post classification change detection method. The obtained overall accuracy for the years 1987 and 2017 was determined to be 0.87 and 0.96, followed by a Kappa coefficient 0.80 and 0.94. The change detection results revealed a significant decrease in the agricultural area, while there was an increase in mangrove forest, shrimp/fish farm, and bareland area. The results suggest that interconversion of land use and land cover is affecting the landscape dynamics within the study area.

Adsorption of formaldehyde vapor by amine-functionalized mesoporous silica materials

The amine-functionalized mesoporous silica materials were prepared via the co-condensation reaction of tetraethoxysilane and three types of organoalkoxysilanes： 3-aminopropyl-trimethoxysilane, n-（2-aminoethyl）-3-aminopropyltrimethoxysilane, and 3-（2-（2- aminoehtylamino）ethylamino） propyl-trimethoxysilane. Cetyltrimethylammonium bromide was used as a template for forming pores, Specific surface area and pore volume of the amine-functionalized mesoporous silica materials were determined using surface area and pore size analyzer. Fourier transform infrared （FTIR） spectroscope was employed for identifying the functional groups on pore surface. In addition, the amine-functionalized mesoporous silica materials were applied as adsorbents for adsorbing formaldehyde vapor. FTIR spectra showed the evidence of the reaction between formaldehyde molecules and amine groups on pore surface of adsorbents. The equilibrium data of formaldehyde adsorbed on the adsorbents were analyzed using the Langmuir, Freundlich and Temkin isotherm. The sample functionalized from n-（2-aminoethyl）-3-aminopropyltrimethoxysilane showed the highest adsorption capacity owing to its amine groups and the large pore diameter.

Modelling of a tubular solid oxide fuel cell with different designs of indirect internal reformer

The cell performance and temperature gradient of a tubular solid oxide fuel cell with indirect internal reformer （IIR-SOFC） fuelled by natural gas, containing a typical catalytic packed-bed reformer, a catalytic coated wall reformer, a catalytic annular reformer, and a novel catalytic annular-coated wall reformer were investigated with an aim to determine the most efficient internal reformer system. Among the four reformer designs, IIR-SOFC containing an annular-coated wall reformer exhibited the highest performance in terms of cell power density （0.67 W.cm 2） and electrical efficiency （68%） with an acceptable temperature gradient and a moderate pressure drop across the reformer （3.53 × 10 5 kPa）. IIR-SOFC with an annular-coated wall reformer was then studied over a range of operating conditions： inlet fuel temperature, operating pressure, steam to carbon （S ： C） ratio, gas flow pattern （co-flow and counter-flow pattern）, and natural gas compositions. The simulation results showed that the temperature gradient across the reformer could not be decreased using a lower fuel inlet temperature （1223 K-1173 K） and both the power density and electrical efficiency of the cell also decreased by lowering fuel inlet temperature. Operating in higher pressure mode （1-10 bar） improved the temperature gradient and cell performance. Increasing the S ： C ratio from 2 ： 1 to 4：1 could decrease the temperature drop across the reformer but also decrease the cell performance. The average temperature gradient was higher and smoother in IIR-SOFC under a co-flow pattern than that under a counter-flow pattern, leading to lower overpotential and higher cell performance. Natural gas compositions significantly affected the cell performance and temperature gradient. Natural gas containing lower methane content provided smoother temperature gradient in the system but showed lower power density and electrical efficiency.

Effects of Biochar Particle Size on Methane Emissions from Rice Cultivation

Biochar amendment is generally recognized as an effective mitigation option of methane(CH_(4))emissions from rice cultivation.Although its mitigation mechanisms are not well understood,the potential relevance of surface area and porosity of biochar has been discussed.This study aimed to evaluate the application of different biochar particle sizes on CH_(4) production,oxidation,and emissions from rice cultivation in a clay loam soil,based on the assumption that porosity and surface area of biochar are directly related to its mitigation effects.Rice was grown under greenhouse conditions for two growing seasons,either with 0.5–2 mm(small,SB)or with 2–4 mm(large,LB)biochar.The results show that both sizes of biochar increased soil pH and redox potential(Eh)during rice growth.Soil dissolved organic carbon(DOC),nitrate(NO^(−)_(3)),and sulfate(SO^(2−)_(4))also increased under both biochar amendments,but size effects were not observed.SB and LB suppressed the abundance of CH_(4) producers(methanogens)but stimulated the abundance of CH_(4) consumers(methanotrophs).The increase of soil Eh and electron acceptors(NO^(−)_(3)and SO^(2−)_(4))indicated the increase in soil oxidation capacity is a barrier to CH_(4) production by methanogens in both biochar treatments.Laboratory incubation experiments showed that CH_(4) production activity was significantly(p≤0.05)reduced by 18.5%using SB and by 11.3%using LB compared to the control.In contrast,the stimulation of methanotrophs promoted greater CH_(4) oxidation activity by 15.0%in SB and 18.7%in LB compared to the control.It shows that CH_(4) production was reduced more by larger surface area biochar(SB),while a greater increase in CH_(4) oxidation was found using larger pore volume biochar(LB).The effects on CH_(4) production were more pronounced than those on CH_(4) oxidation,resulting in a greater reduction of cumulative CH_(4) emissions by SB than LB(by 26.6%and 19.9%compared to control,respectively).

Carbon Monoxide Emission and Concentration Models for Chiang Mai Urban Area

An emission inventory containing emissions from traffic and other sources was complied. Based on the analysis, Carbon Monoxide （CO） emissions from traffic play a very important role in CO levels in Chiang Mai area. Analysis showed that CO emissions from traffic during rush hours contributed approximately 90% of total CO emissions. Regional Atmospheric Modeling System （RAMS） was applied to simulate wind fields and temperatures in the Chiang Mai area, and eight ca^es were selected to study annual variations in wind fields and temperatures. Model results can reflect major features of wind fields and diurnal variations in temperatures. For evaluating the model performance, model results were compared with observed wind speed, wind direction and temperature, which were monitored at a meteorological tower. Comparison showed that model results are in good agreement with observations, and the model captured many of the observed features. HYbrid Particle And Concentration Transport model （HYPACT） was used to simulate CO concentration in the Chiang Mai area. Model results generally agree well with observed CO concentrations at the air quality monitoring stations, and can explain observed CO diurnal variations.

Effect of samarium and praseodymium addition on water gas shift performance of Co/CeO2 catalysts

The performance of Co supported over ceria and doped ceria(by Sm and Pr)catalysts towards the water gas shift reaction was studied for the removal of CO from syngas to produce high purity hydrogen for a fuel cell application.It is found that 1%Co/Ce-5%Sm-O yields the highest catalytic performance towards this reaction compared with undoped-Sm and doped-Pr.An addition of Sm onto ceria support reveals a small crystallite size with high surface area and well dispersed cobalt on ceria surface.Moreover,a presence of Sm increases the reducibility of cobalt species and surface oxygen.The positive effect of Sm on increasing the WGS activity of Co/CeO2 is because Sm contributes to the reduction of Ce^4+to Ce3+which gives rise to oxygen vacancies and facilitates the electron movement at the surface leading to an ease of surface reduction.

Degradative solvent extraction of low-rank coal:Role of water on pyrolysis mechanism of low-rank coal in a highly-dispersed medium

A degradative solvent extraction(DSE)method was proposed to upgrade low-rank coals(LRC)for their cascaded utilizations in a highly-dispersed medium.The derived products exhibited well improved properties in comparison to the raw LRCs.Previously,the LRCs were pre-dried to eliminate the potential impact of the varied water content of raw LRCs,but in light of the abundant water in fresh coals,the hydrolyzing effect of water on coals under heating,and the energy cost to pre-dry the LRCs,it is consequently essential to clarify the effect of water so as to verify the necessity of pre-drying process.In this study,the roles of inherent water and extra-added water were respectively investigated,using dried,raw and wet coals from two typical LRCs.The results show that increasing the moisture content of raw LRCs contributed to the extraction ability of DSE method without noticeably changing the elemental composition,chemical structure and thermal decomposition behavior of extractable products,thus pre-drying of LRCs before DSE treatment was proven unnecessary.Additionally,the roles of the inherent water were concluded as:1)leading to the formation of stable covalent bond during drying process;and 2)acting as H donor to promote extraction ability,while the added water can only function as H donor.Since excessive water will increase the pressure during DSE treatment and lead to the waste water treatment,the LRCs with a water content between 10%and 30%were consequently recommended for the practical application of DSE treatment.