Effect of changing groundwater levels caused by land-use changes on greenhouse gas fluxes from tropical peat lands

Monthly measurements of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) fluxes in peat soils were carried out and compared with groundwater level over a year at four sites (drained forest, upland cassava,upland and lowland paddy fields) located in Jambi province, Indonesia. Fluxes from swamp forest soils were also measured once per year as the native state of this investigated area. Land-use change from drained forest to lowland paddy field significantly decreased the CO₂ (from 266 to 30 mg C m^–2 h^–1) and N₂O fluxes (from 25.4 to 3.8 g N m^–2 h^–1), but increased the CH₄ flux (from 0.1 to 4.2 mg C m^–2 h^–1) in the soils. Change from drained forest to cassava field significantly increased N₂O flux (from 25.4 to 62.2 g N m^–2 h^–1), but had no significant influence on CO₂ (from 266 to 200 mg C m^–2 h^–1) and CH₄ fluxes (from 0.1 to 0.3 mg C m^–2 h^–1) in the soils. Averaged CO₂ fluxes in the swamp forests (94 mg C m^–2 h^–1) were estimated to be one-third of that in the drained forest. Groundwater levels of drained forest and upland crop fields had been lowered by drainage ditches while swamp forest and lowland paddy field were flooded, although groundwater levels were also affected by precipitation. Groundwater levels were negatively related to CO₂ flux but positively related to CH₄ flux at all investigation sites. The peak of the N₂O flux was observed at –20 cm of groundwater level. Lowering the groundwater level by 10 cm from the soil surface resulted in a 50 increase in CO₂ emission (from 109.1 to 162.4 mg C m^–2 h^–1) and a 25% decrease in CH₄ emission (from 0.440 to 0.325 mg C m^–2 h^–1) in this study. These results suggest that lowering of groundwater level by the drainage ditches in the peat lands contributes to global warming and devastation of fields. Swamp forest was probably the best land-use management in peat lands to suppress the carbon loss and greenhouse gas emission. Lowland paddy field was a better agricultural system in the peat lands in terms of C sequestration and greenhouse gas emission. Carbon loss from lowland paddy field was one-eighth of that of the other upland crop systems, although the Global Warming Potential was almost the same level as that of the other upland crop systems because of CH₄ emission through rice plants.     

Ring‐opening of γ‐valerolactone with amino compounds

Diols obtained by the ring‐opening of biomass‐based γ‐valerolactone (GVL) are potentially valuable building blocks that can be used as precursors in the manufacture of green polymers and resins. We report here a study on the ring‐opening of GVL through adding amine compounds. The reactivity of the applied amine compounds in this ring‐opening was tested by varying the structure of the amine compounds. Both mono‐amines (ammonium, 2‐aminoethanol, 2‐phenylethylamine, and morpholine) and di‐amines (1,2‐diaminoethane, 1,2‐diaminopropane, and piperazine) were used. The study showed that steric hindrance at the reacting amine‐function plays a more prominent role than local point charge. To optimize the yield of the desired di‐functional monomers, the ring‐opening of GVL with 1,2‐diaminoethane (1,2‐DE) was studied in more detail. Reaction temperature (25–100°C), reaction time, and molar ratio of the reactants appeared to be the determining processing parameters. These were found to be more important than the use of catalysts (triphenylphosphine, Tin(II)‐2‐ethylhexanoate, Ytterbium(III)trifuoromethanesulfonate, AlCl₃, and SnCl₂) and solvent polarity (methanol, DMA, DMSO, and water). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synchrotron crystal and local structures,microstructure, and electrical characterization of Cu-doped LiFePO4/C via dissolution method with ironstone as Fe source

Journal of Materials Science: Materials in Electronics - Powders of lithium iron phosphate (LFP) with Cu doping and carbon coating were prepared by a dissolution method using Fe sourced from...     

Thermal and dynamic mechanical properties of polyethylene glycol/quartz composites for phase change materials

Polyethylene glycol (PEG)/quartz (denoted as BP/Q) composites have been investigated as candidates of phase change materials (PCMs) due to their thermomechanical properties around the glass transition temperature as well as thermal properties between 30 and 600 °C. Quartz (q-SiO₂) powders were extracted from local sand in Tanah Laut, Pelaihari, South Kalimantan, Indonesia. The composites were prepared by dispersing q-SiO₂ powders in the PEG matrix followed by the wet mixing process. The thermal properties of the composites were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), while the thermomechanical properties were examined using a dynamic mechanical analyzer (DMA) in a three-point bending mode around the PEG glass transition temperature range (−100–50°C). The morphology and interface bonding were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From the DSC measurement, the endothermic peak of the composites showed a shift of approximately 7–12 °C toward higher temperatures than that of the pure polymer. The melting enthalpy values (ΔH_m) of the BP/Q composites covered the required PCM application range, that is, between 139 and 182 J/g. The TGA of the composites showed that thermal degradation occurs in the range of 250–450 °C. We found that solid–solid PCMs (ssPCMs) were successfully fabricated with the addition of 10 and 20 wt% q-SiO₂. From DMA characterization, the BP/Q 20 wt% composite exhibited the maximum E’ and the minimum energy dissipation (E”). Its E’ value was approximately 250 MPa more than that of the pure PEG. The glass transition (T_g) temperatures of PEG and BP/Q composites (5, 10, and 20 wt%) were around −24.5, −19.1, −17.1, and − 5.3 °C, respectively. In addition, the E” and tan δ values decreased with q-SiO₂ filler content. Furthermore, the Cole-Cole plots of the BP/Q composites revealed a better interfacial bonding between the q-SiO₂ and the PEG matrix in the composites with higher silica content. A compact morphology was shown by the BP/Q 20 wt% composite due to high silica concentration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48130.