The Characteristics of Tropospheric Ozone Seasonality Observed from Ozone Soundings at Pohang, Korea

This paper presents the first analysis of vertical ozone sounding measurements over Pohang, Korea. The main focus is to analyze the seasonal variation of vertical ozone profiles and determine the mechanisms controlling ozone seasonality. The maxima ozone at the surface and in the free troposphere are observed in May and June, respectively. In comparison with the ozone seasonality at Oki (near sea level) and Happo (altitude of 1840 m) in Japan, which are located at the same latitude as of Pohang, we have found that the time of the ozone maximum at the Japanese sites is always a month earlier than at Pohang. Analysis of the wind flow at the surface shows that the wind shifts from westerly to southerly in May over Japan, but in June over Pohang. However, this wind shift above boundary layer occurs a month later. This wind shift results in significantly smaller amounts of ozone because the southerly wind brings clean wet tropical air. It has been suggested that the spring ozone maximum in the lower troposphere is due to polluted air transported from China. However, an enhanced ozone amount over the free troposphere in June appears to have a different origin. A tongue-like structure in the time-height cross-section of ozone concentrations, which starts from the stratosphere and extends to the middle troposphere, suggests that the ozone enhancement occurs due to a gradual migration of ozone from the stratosphere. The high frequency of dry air with elevated ozone concentrations in the upper troposphere in June suggests that the air is transported from the stratosphere. HYSPLIT trajectory analysis supports the hypothesis that enhanced ozone in the free troposphere is not likely due to transport from sources of anthropogenic activity.     

Biodegradable corn starch loose- fill. I. The effect of the extrusion temperature on the physical properties of loose-fill

Extrusion with an intermeshing corotating twin-screw extruder with a limited amount of water caused structural changes in corn starch. The structural changes resulted in a transformation-from a semicrystalline to an amorphous state and the development of orientation of molecular chains in the amorphous region during extrusion. These structural changes, in turn, caused an increase in theT _g, tensile strength, and resilience of the extruded corn starch. Our experimental results showed that the tensile properties and resilience of the expanded corn starch extruded at 240‡C were the best: tensile strength, 1.7 kPa; tensile modulus, 40.4 kPa; and resilience, 57.2%. Extrusion produced an expanded corn starch suitable for protective loose-fill.     

Adsorption and clay-catalyzed degradation of erythromycin A on homoionic clays

Erythromycin has been widely used in food-producing animals and in humans, and is frequently detected as an organic pollutant in U.S. streams. In batch experiments with homoionic clays, the Freundlich isotherms were determined at 10 and 25 degrees C. The adsorption of erythromycin A was strongly influenced by clay type, exchanged cations, the pH of the bulk solutions, and the acidity of clay surfaces. The formation of clay-erythromycin A complexes was thermodynamically favorable except for K+- and Fe3+-exchanged montmorillonites, since the reactions were exothermic (deltaH(o) > 0) and the systems became stable (deltaS(o) > 0). Clays catalyzed the erythromycin A degradation by the hydrolysis of the neutral sugar and the multiple dehydrations. The surface acidity of clay surface enhanced the rate of clay-catalyzed degradation of erythromycin A. In addition, the Fe3+-exchanged clay minerals seemed to have an electrostatic interaction with the erythromycin A molecule, by which the hydrolysis of the neutral sugar was influenced.     

Interpreting complex geochemistry of groundwater in a coastal paddy field near a mine using isotopic signatures of sulfate and water

Environmental Geochemistry and Health - In the area around the abandoned Seoseong mine, South Korea, coastal paddy fields undergo seawater intrusion and possible sulfate reduction. Here, channel...     

Soil sampling strategies for site assessments in petroleum-contaminated areas

Environmental site assessments are frequently executed for monitoring and remediation performance evaluation purposes, especially in total petroleum hydrocarbon (TPH)-contaminated areas, such as gas stations. As a key issue, reproducibility of the assessment results must be ensured, especially if attempts are made to compare results between different institutions. Although it is widely known that uncertainties associated with soil sampling are much higher than those with chemical analyses, field guides or protocols to deal with these uncertainties are not stipulated in detail in the relevant regulations, causing serious errors and distortion of the reliability of environmental site assessments. In this research, uncertainties associated with soil sampling and sample reduction for chemical analysis were quantified using laboratory-scale experiments and the theory of sampling. The research results showed that the TPH mass assessed by sampling tends to be overestimated and sampling errors are high, especially for the low range of TPH concentrations. Homogenization of soil was found to be an efficient method to suppress uncertainty, but high-resolution sampling could be an essential way to minimize this.     

Biogas productivity of algal residues from bioethanol production

Journal of Material Cycles and Waste Management - The purpose of this study was to investigate biogas productivity of algal residues from bioethanol production. Pre-treatment based on enzyme was...     

A numerical simulation model of cyclic hardening behavior of AC4C-T6 for LNG cargo pump using finite element analysis

This paper is concerned with the evaluation of cyclic hardening models within the stress–strain behavior of aluminum alloy AC4C-T6 that can be used to LNG cargo pump operating in cryogenic temperature. To insure the strength assessment of LNG cargo pump, material model of cyclic hardening and plasticity for aluminum alloy AC4C-T6 is investigated through FEA (Finite Element Analysis) with various hardening options including linear and non-linear hardening, isotropic and kinematic hardening, and combined hardening model. Monotonic tensile and cyclic tensile experiments for AC4C-T6 alloy were performed at room temperature and temperature of ?165 °C. Parameters of each hardening model are obtained from the experimental data; thus five hardening models are numerically simulated thereafter. Appropriate hardening models which describe the cyclic stress–strain relationship are investigated through the simulations of cyclic hardening behavior by FEA. In order to verify the predicted behavior of cyclic hardening obtained by FEA, the results of FEA and those measured by experiments are compared.     

Cooperative prey capture by young subsocial spiders: II. Behavioral mechanism

Subsocial spiders demonstrate an intermediate stage in the evolution of permanent sociality. Cooperative hunting is an important attribute of their sociality, but has not been documented in subsocial arthropods. After cannibalizing their mother, young of the subsocial spider Amaurobius ferox (Araneae, Amaurobiidae) remain together for several instars and feed communally. We monitored the collective prey capture behavior of the spiderlings. All the clutches showed collective capturing sequence (latency–orientation–moving–touching–seizing–feeding) toward the prey that was 10 times more massive than each individual. The first three individuals that exhibited attacking behavior were responsible for 90% of the total number of attacks, while 68% of the individuals within the group never exhibited attacks during the first 10 min following the introduction of prey into the communal web. First arriving individuals at the prey most often seized the antennae and legs of the prey, which probably facilitate access to the prey for subsequent individuals. The spiderlings that arrived later occupied more likely the abdomen and thorax, which contain more nutrition than the extremities occupied earlier. The individual apportionment of collective hunting behavior suggests a coordinated teamwork among individuals.     

厌氧/生物滤池/潜流人工湿地组合工艺处理农村生活污水效果评估

采用"厌氧/生物滤池/潜流人工湿地"组合工艺处理农村生活污水,系统稳定后表现出良好的净污效能,其中TSS、COD和NH4+-N的去除效率分别为97.7%、89.6%和63.3%,但对TN和TP的处理效果相对偏低,仅为26.7%和32.4%。组合工艺中,厌氧池、生物滤池和人工湿地对TSS去除的贡献率分别为35.7%、9.8%和52.1%,对COD去除的贡献分别为22.4%、33.8%和31.3%,对TN去除的贡献5.4%、0.0%和22.0%。生物滤池主要表现为COD和NH4+-N的强化处理,而人工湿地则能有效去除TSS、TP及TN。因此,在保持工艺不变的情况下,需优化工艺运行参数,保持碳源供给与微生物脱氮除磷之间的平衡。     

The impact of nudging coefficient for the initialization on the atmospheric flow field and the photochemical ozone concentration of Seoul,Korea

In order to incorporate correctly the large or local scale circulation in the model, a nudging term is introduced into the equation of motion. Nudging effects should be included properly in the model to reduce the uncertainties and improve the air flow field. To improve the meteorological components, the nudging coefficient should perform the adequate influence on complex area for the model initialization technique which related to data reliability and error suppression. Several numerical experiments have been undertaken in order to evaluate the effects on air quality modeling by comparing the performance of the meteorological result with variable nudging coefficient experiment. All experiments are calculated by the upper wind conditions (synoptic or asynoptic condition), respectively. Consequently, it is important to examine the model response to nudging effect of wind and mass information. The MM5–CMAQ model was used to assess the ozone differences in each case, during the episode day in Seoul, Korea and we revealed that there were large differences in the ozone concentration for each run.These results suggest that for the appropriate simulation of large or small-scale circulations, nudging considering the synoptic and asynoptic nudging coefficient does have a clear advantage over dynamic initialization, so appropriate limitation of these nudging coefficient values on its upper wind conditions is necessary before making an assessment. The statistical verifications showed that adequate nudging coefficient for both wind and temperature data throughout the model had a consistently positive impact on the atmospheric and air quality field. On the case dominated by large-scale circulation, a large nudging coefficient shows a minor improvement in the atmospheric and air quality field. However, when small-scale convection is present, the large nudging coefficient produces consistent improvement in the atmospheric and air quality field.