• Journal of The Korean Society of Grassland and Forage Science
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• v.44 no.2
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• pp.133-139
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• 2024

This study aimed to evaluate the efficiency of combining acidification with adsorbents (zeolite and biochar) to mitigate the environmental impacts of pig slurry, focusing on ammonia (NH₃) emission and nitrate (NO₃^-) leaching. The four treatments were applied: 1) pig slurry (PS) alone as a control, 2) acidified PS (AP), 3) acidified pig slurry with zeolite (APZ), and 4) acidified pig slurry with biochar (APB). The AP mitigates NH₃ emission and NO₃^- leaching compared to PS alone. Acidification reduced the cumulative NH₃ emission and its emission factor by 35.9% and 12.5%, respectively. The APZ and APB increased NH₄⁺-N concentration, with the highest level in APB, compared to AP. The NH₄⁺ adsorption capacity of APB (0.90 mg g^-1) was higher than that of APZ (0.63 mg g^-1). The APB and APZ treatments induced less NH₃ emission compared to AP. The cumulative NH₃ emission was reduced by 12.2% and 27.6% in APZ and APB, respectively, compared to AP treatment. NO₃^- leaching began to appear on days 12 and 13, and its peak reached on days 16 and 17, which were later than AP. The cumulative NO₃^- leaching decreased by 17.7% and 25.0% in APZ and APB, respectively, compared to AP treatment. These results suggest that combining biochar or zeolite with acidified pig slurry is an effective method to mitigate NH₃ emission and NO₃^- leaching, with biochar being particularly effective.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.571-580
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• 2008

The influence of bacterial stress on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Several physical and chemical stresses (i.e., heating, adding methane producing inhibitor and chemical acidification) were adapted as a pretreament of the seed sludge. In this experiment, the cultivation temperature were set at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) with adjusting pH at 5, 6, and 7 when using the mixture of food waste and activated sludge as a substrate. In conjunction with the pretreatment, hydrogen production was significantly enhanced as compared with that from untreated sludge. However, less biogas (hydrogen and methane) was produced without the pH control, resulted from the decrease of pH to below 4, mainly due to the formation of VFAs. Hydrogen and carbon dioxide gas were analyzed as main components of the biogas while methane not detected. With an application of chemical acidification, the highest hydrogen production value of 248 ml/l/day achieved at pH 7 and $35^{\circ}C$. In addition, more hydrogen gas produced when the ratio of butyric/acetic acid ratio increased. The optimum pH and temperature for hydrogen production were found to be 7 and $35^{\circ}C$, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.21-26
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• 2002

Effects of cadmium (Cd) intoxication on renal endosomal accumulation of organic cations $(OC^+)$ were studied in rats using $^{14}C-tetraethylammnium$ (TEA) as a substrate. Cd intoxication was induced by s.c. injections of 2 mg Cd/kg/day for $2{\sim}3$ weeks. Renal cortical endosomes were isolated and the endosomal acidification (acridine orange fluorescence change) and TEA uptake (Millipore filtration technique) were assessed. The TEA uptake was an uphill transport mediated by $H^+/OC^+$ antiporter driven by the pH gradient established by $H^+-ATPase.$ In endosomes of Cd-intoxicated rats, the ATP-dependent TEA uptake was markedly attenuated due to inhibition of endosomal acidification as well as $H^+/TEA$ antiport. In kinetic analysis of $H^+/TEA$ antiport, Vmax was reduced and Km was increased in the Cd group. Inhibition of $H^+/TEA$ antiport was also observed in normal endosomes directly exposed to free Cd (but not Cd-metallothionein complex, CdMt) in vitro. These data suggest that during chronic Cd exposure, free Cd ions liberated by lysosomal degradation of CdMt in proximal tubule cells may impair the endosomal accumulation of $OC^+$ by directly inhibiting the $H^+/OC^+$ antiporter activity and indirectly by reducing the intravesicular acidification, the driving force for $H^+/OC^+$ exchange.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.4 s.117
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• pp.53-60
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• 2006

Paper materials for long term conservation suffer slowly mechanical and chemical deterioration, the extent of which may depend upon their conservation environment. Those deterioration includes discoloring, low moisture content, acidification, and brittleness. To slow deterioration, washing treatment, deacidification, and polymer reinforcement on paper materials are usually used. One easy and simple method of fixing low moisture content and acidification was an washing method, and we used both distilled and alkali water in washing method in this study. Alkali water is electrolyzed cathode water of high pH, and has no alkali metal ions in it. Experiment showed that washing treatment with both distilled and alkali water gave improvement in raising moisture content, pH, and mechanical strength of paper materials even after severe accelerated aging test. Advantageous effect of alkali water over distilled water on preventing deterioation was also shown clearly.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.34-39
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• 2005

The performance of elutriated acid fermentation with slurry-type piggery waste was investigated, especially to evaluate the effects of temperature and pre-treatment. In the first phase, the acid elutriation reactor with piggery waste after centrifugation operated at both mesophilic and thermophilic conditions to evaluate the effect of temperature. Solubilization yield($gVFAs/gSCOD_{prod.}$) and acidification rate($gVFAs/gSCOD_{prod.}$) in the thermophilic digestion were 0.45 and 0.55, which were higher than those of the mesophilic digestion, 0.25 and 0.45. In addition, the acid elutriation reactor at thermophilic temperature is more effective in removing e-coli. In the second phase, the acid elutriation reactor was fed with piggery waste before centrifugation. With piggery wastes before centrifugation, the solubilization yield and the acidificaton rate were 0.40 and 0.80, respectively, which were higher than the rates using piggery waste after centrifugation at both mesophilic and thermophilic conditions. The higher sludge volume reduction of 80% benefits sludge management. Furthermore, economical advantages can be achieved by removing the pre-treatment process, such as centrifugation. Consequently, the treatment with piggery waste before centrifugation proved to be effective. Also, the optimum temperature condition was estimated at mesophilic or thermophilic conditions, considering solubilization yields and acidification rates, though the system should be heated.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.348-352
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• 2007

To investigate the effects of soil pH on plants, the seedlings of french marigold (Tagetes patula L.) was transplanted into the soils acidified with $H_{2}SO_{4}$ solutions (pH 5.3, 4.5, 3.9, 3.5). The level of malondialdehyde was significantly increased by soil acidification. As the pH levels decreased from 5.3 to 3.5, the contents of dehydroascorbate and oxidized glutathione of the plant were significantly increased. The antioxidative enzyme activities of the plant affected by soil acidification were increased as the pH decreased.

• ALGAE
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• v.33 no.4
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• pp.359-366
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• 2018

Mesocosm experiments conducted for ecological purposes have become increasingly popular because they can provide a holistic understanding of the biological complexities associated with natural systems. This paper describes a new outdoor mesocosm designed for $CO_2$ perturbation experiments of benthos. Manipulated the carbonate chemistry in a continuous flow-through system can be parallelized with diurnal changes, while irradiance, temperature, and nutrients can vary according to the local environment. A target hydrogen ion activity (pH) of seawater was sufficiently stabilized and maintained within 4 h after dilution, which was initiated by the ratio of $CO_2$-saturated seawater to ambient seawater. Specifically, pH and $CO_2$ partial pressure ($pCO_2$) levels gradually varied from 8.05-7.28 and $375-2,691{\mu}atm$, respectively, over a range of dilution ratios. This mesocosm can successfully manipulate the pH and $pCO_2$ of seawater, and it demonstrates suitability for ocean acidification experiments on benthic communities.

• ALGAE
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• v.36 no.4
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• pp.285-298
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• 2021

The amount of CO₂ absorbed by the oceans continues to rise, resulting in further acidification, altering some functional traits of phytoplankton. To understand the effect of elevated partial pressures of CO₂ (pCO₂) on functional traits of dinoflagellates Alexandrium affine and A. pacificum, the cardinal temperatures and chain formation extent were examined under two pCO₂ (400 and 1,000 µatm) over the range of temperature expected to be associated with growth. The growth rate and chain formation extent of A. affine increased with higher pCO₂, showing significant changes in cardinal temperatures and a substantial increase in middle chain-length (4-8 cells) fractionation under elevated pCO₂ condition. By contrast, there were no significant differences in specific growth rate and any chain-length fractionation of A. pacificum between ambient and elevated pCO₂ conditions. The observed interspecies variation in the functional traits may reflect differences in ability of species to respond to environmental change with plasticity. Moreover, it allows us to understand the shifting biogeography of marine phytoplankton and predict their phenology in the Korea Strait.

• Korean Journal of Food Science and Technology
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• v.24 no.1
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• pp.42-48
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• 1992

The rate and extent of coagulation of milk using fast acidification with 0.1 N HCl were monitored by changes in viscosity and turbidity at various temperatures and pH. Also the gelation rate of milk using slow acidification with D-glucono-${\delta}$-lactone was measured in a small strain rheological scanner. Coagulation of milk casein occurred in a specific pH range and was accompanied by an abrupt increase in viscosity at pH 5.0. Acid coagulation rate was enhanced by increasing temperature from $20^{\circ}C{\sim}50^{\circ}C$, and the maximum rate was shown around pH 5.0. The addition of salt ($CaCl_{2}$) reduced the maximum coagulation rate at all temperature ranges and shifted the pH ranges for maximum coagulation rate and the onset pH of coagulation. The onset of gelation and the rate of network formation during slow acidification were facilitated by Cl ion, but suppressed by SCN-ion, as indicated by the rate of rigidity development. The susceptibility to syneresis was greater in the gel made at lower temperature and around pH 4.6, while preheated milk at $90^{\circ}C$ for 5 min prior to acidification showed the same syneresis profile at all heating temperatures ($60{\sim}90^{\circ}C$).

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.91-109
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• 2022

The ocean is a significant sink for atmospheric anthropogenic CO₂, absorbing one-third of the total CO₂ emitted by human activities. In return, oceans have experienced significant declines in seawater pH and the aragonite saturation state also called ocean acidification. This study evaluates the distribution of aragonite saturation state, an indicator to assess the potential threat from ocean acidification, by combining newly obtained data from the west coast of South Korea with previous datasets covering the Yellow Sea, East Sea, northern South China Sea, and southeast coast of South Korea. In general, offshore waters absorb atmospheric CO₂; however, most of the collected water samples show aragonite oversaturation. On the southeast coast, the aragonite saturation state was significantly affected by river discharge and associated variables, such as freshwater input with nutrients, seasonal stratification, biological carbon fixation, and bacterial remineralization. In summer, hypoxia and mixing with relatively acidic freshwater made the Jinhae and Gwangyang Bays undersaturated with respect to aragonite, possibly threatening marine organisms with CaCO₃ shells. However, widespread aragonite undersaturation was not observed on the west coast, which receives considerable river water discharge. In addition, occasional upwelling events may have worsened the ocean acidification in the southwestern part of the East Sea. These results highlight the importance of investigating site-specific ocean acidification processes in coastal waters. Along with the above-mentioned seasonal factors, the dissolution of atmospheric CO₂ and the deposition of atmospheric acidic substances will continue to reduce the aragonite saturation state in Korean waters. To protect marine ecosystems and resources, an ocean acidification monitoring program should be established for Korean waters.