Estimation and field measurement of methane emission from waste landfills in Hanoi, Vietnam

A methodology for estimating the methane emissions from waste landfills in Hanoi, Vietnam, as part of a case study on Asian cities, was derived based on a survey of documents and statistics related to waste management, interviews with persons in charge, and field investigations at landfill sites. The waste management system in Hanoi was analyzed to evaluate the methane emissions from waste landfill sites. The quantity of waste deposited into the landfill was evaluated from an investigation of the waste stream. The composition of municipal waste was surveyed in several districts in the Hanoi city area, and the quantities of degradable organic waste that had been deposited into landfill for the past 15 years were estimated. Field surveys on methane emissions from landfills of different ages (0.5, 2, and 8 years) were conducted and their methane emissions were estimated to be 120, 22.5, and 4.38 ml/min/m², respectively. The first-order reaction rate of methane generation was obtained as 0.51/year. Methane emissions from waste landfills were calculated by a first-order decay model using this emission factor and the amount of landfilled degradable waste. The estimates of methane emissions using the model accorded well with the estimates of the field survey. These results revealed that methane emissions from waste landfills estimated by regional-specific and precise information on the waste stream are essential for accurately determining the behavior of methane emissions from waste landfills in the past, present, and future.     

Performance evaluation of intermediate cover soil barrier for removal of heavy metals in landfill leachate

This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces.     

Effects of chronic ozone exposure on growth, root respiration and nutrient uptake of rice plants

To clarify the response of growth and root functions to low concentrations of ozone (O(3)), rice plants (Oryza sativa L.) were exposed to O(3) at 0.0 (control), 0.05 and 0.10 ppm for 8 weeks from vegetative to early heading stages. Exposure to 0.05 ppm O(3) tended to slightly stimulate the dry weight of whole plants up to 5 weeks and then slightly decrease the dry weight of whole plants. However, these effects were statistically significant only at 6 weeks. Exposure to 0.10 ppm O(3) reduced the dry weight of whole plants by 50% at 5 and 6 weeks, and thereafter the reduction of the dry weight of whole plants was gradually alleviated. Those changes in dry weight can be accounted for by a decrease or increase in the relative growth rate (RGR). The changes in the RGR caused by 0.05 and 0.10 ppm O(3) could be mainly attributed to the effect of O(3) on the net assimilation rate. Root/shoot ratio was lowered by both 0.05 and 0.10 ppm O(3) throughout the exposure period. The root/shoot ratio which had severely decreased at 0.10 ppm O(3) in the first half period of exposure (1-4 weeks) became close to the control in the latter part of exposure (5-8 weeks). Time-course changes in NH(4)-N root uptake rate were similar to those in the root/shoot ratio especially for 0.10 ppm O(3). On the other hand, root respiration increased from the middle to later periods. Since it is to be supposed that plants grown under stressed conditions change the ratio of plant organ weight to achieve balance between the proportion of shoots to roots in the plant and their activity for maintaining plant growth, these changes in root/shoot ratio and nitrogen uptake rate under long-term exposure can be considered to be an adaptive response to maintain rice growth under O(3) stress.     

e-JIKEI Network using e-JIKEI Cameras: Community security using considerable number of cheap stand-alone cameras

The e-JIKEI Network, a concept for realizing a safer and more comfortable community, and the e-JIKEI Camera, a stand-alone camera developed for the e-JIKEI Network, are reviewed. The concept of the e-JIKEI Network is that residents view their surroundings using cheap cameras, which act as their eyes, and home computers, which act as their brains, using the free software provided by us through the Internet. For the complete protection of the privacy of ordinary citizens, we propose a second concept supporting the concept of the e-JIKEI Network; in this concept, those who own and manage images (owners) and those who have the right to view these images (viewers) are separated by means of image encryption. Since 2004, the “Dairi-EYE” series, a free software for a personal computer (PC)-based system, has been distributed through our website. However, the use of PCs is not very user-friendly. Therefore, an all-in-one device called the “e-JIKEI Camera” has been developed. A social experiment of the e-JIKEI Network using e-JIKEI Cameras has been carried out.     

Development of dioxin toxicity evaluation method in human milk by enzyme-linked immunosorbent assay--assay validation for human milk

In this study, the development of a toxicity evaluation method for dioxins in human milk by enzyme-linked immunosorbent assay (ELISA) was reported. A total of 17 human milk samples were tested by ELISA and by gas chromatography/mass spectrometry (GC/MS) to assess whether the ELISA performed on samples obtained from primiparas could be considered as reliable enough for identifying a dioxins contamination in human milk. The concept of toxicity equivalent quantity (TEQ) screening was validated by comparing TEQ values for a set of human milk samples to the ELISA responses predicted for those samples. A fairly good correlation (r=0.920) between immunoassay and GC/MS was achieved for human milk. This ELISA should be useful for biological samples monitoring.     

Incorporation of 32PO4 directly taken-up into acid-soluble phosphates of Artemia salina

A study of the direct uptake by Artemia salina of phosphate ion from the medium and its incorporation into acid-soluble organic phosphorous compounds over a range of exposure time from 2 to 30 min, using ³²PO₄ ion, indicated that the phosphate ion was directly taken up and was rapidly incorporated into the energy-rich compounds, such as adenosine triphosphate (ATP), guanosine triphosphate (GTP), and adenosine diphosphate (ADP), which were separated by ion-exchange chromatography using Dowex-1, X2. Even after an exposure of 2 min, the sum of the radioactivity of nucleotide-fractions was 37.4% of that of the whole acid-soluble extract. The most rapid incorporation of ³²P occurred into ATP, followed by GTP and ADP. The amount of ³²P incorporated into each fraction increased with increased exposure, giving straight lines when the radioactivity of each fraction was plotted against the exposure time on a logarithmic scale. Almost no difference, however, was observed in the distribution rate of ³²P into each fraction at 2, 5, 10 and 30 min. These results show that inorganic phosphate absorbed by A. salina is rapidly incorporated into the energy-rich nucleotides, and that a dynamic equilibrium is established among various acid-soluble phosphorous compounds even after very short periods of time.     

Detonation characteristics of ammonium nitrate and activated carbon mixtures

To better understand the detonation characteristics of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests were carried out for AN/AC mixtures of various compositions and different forms of AN (powdered, prilled, phase stabilized and granular), and the detonation velocity was measured. The powdered AN/AC mixtures gave higher detonation velocities than the other AN forms. For all the AN/AC mixtures, the experimentally observed detonation velocities at each loading density were far below the theoretically predicted values calculated by the CHEETAH code based on thermohydrodynamics, exhibiting so-called non-ideal detonation. The lowest detonation velocity of powdered AN/AC mixtures was obtained as D=1.25 km/s for an AC content of 0.1 wt%. This was considered to be close to the critical condition for stable detonation.     

Modeling of mercury sorption by activated carbon in a confined,a semi-fluidized,and a fluidized bed

A process model was developed to simulate elemental mercury sorption by activated carbon in three distinct beds, namely a confined, a semi-fluidized, and a fluidized bed. The model involved the coupling of a kinetic model based on the mechanisms of surface equilibrium and external mass transfer, and a material balance model based on the tank-in-series approach. For surface equilibrium, three different equilibrium laws were used in the model, namely the Henry's Law, the Langmuir isotherm and the Freundlich isotherm. Literature mercury sorption data were used to determine the best-fit values of parameters for these equilibrium expressions. The parameter-fitted model was then used to simulate mercury sorption processes in the three distinct beds. The simulation parameters were mercury concentration, gas flow rate, adsorption temperature and the degree of semi-fluidization. The simulation results have indicated that the model is capable of describing the literature available mercury sorption data. All the three surface equilibrium laws appear to simulate the adsorption profiles equally well mainly because the sorption process occurs in an extremely low concentration range. The simulation results for the three distinct beds have suggested that the confined bed has the best mercury control performance; however, it generates the highest pressure-drop across the bed. A fluidized bed creates the least pressure drop; however, its sorption performance is poor. A semi-fluidized bed offers acceptable performance with affordable pressure-drops and can be a practical candidate for the process.     

The first ceratopsian dinosaur from South Korea

In 2008, a new basal neoceratopsian was discovered in the Tando beds (Albian) of Tando Basin in South Korea. It represents the first ceratopsian dinosaur in the Korean peninsula and is assigned to Koreaceratops hwaseongensis gen. et sp. nov. Autapomorphies of Koreaceratops include very tall neural spines over five times higher than the associated centra in the distal caudals, and a unique astragalus divided into two fossae by a prominent craniocaudal ridge on the proximal surface. A phylogenetic analysis indicates that Koreaceratops is positioned between Archaeoceratops and all more derived neoceratopsians, and the elongation of caudal neural spines was an important derived character in non-ceratopsid neoceratopsians. The very tall caudal neural spines in Koreaceratops, Montanoceratops, Udanoceratops, Protoceratops, and Bagaceratops appear to be homoplasious, suggesting an independent adaptation, possibly for swimming. Skeletal evidence suggests that obligate quadrupedalism occurred gradually in neoceratopsians progressing from bipedal through facultative quadrupedalism, to complete quadrupedalism in Coronosauria.