• Applied Biological Chemistry
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• 제41권8호
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• pp.587-594
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• 1998

The objective of this research was to characterize effects of Cu or Cd additions on chemistry of soil quality indices, such as pH, EC, cation distribution and buffering capacity. Metals were added at rates ranging from 0 to 400 mg $kg^{-1}$ of soil. Soil solution was sequentially extracted from saturated pastes using vacuum. Concentrations of Cu or Cd remaining in soil solutions were very low as compared to those added to the soils, warranting that most of the added metals were recovered as nonavailable fractions. Adsorption of the added metals released cations into soil solution causing increases of ionic strength of soil solution. At metal additions of $200{\sim}400\;mg\;kg^{-1}$, EC of soil solution increased to as much as $2{\sim}4\;m^{-1}$; salinity levels considered high enough to cause detrimental effects on plant production. More divalent cations than monovalent cations were exchanged by Cu or Cd adsorption. The nutrient buffering capacity of soils was decreased due to the metal adsorption and release of cations. pH of soil solution decreased linearly with increasing metal loading rates, with a decrement of up to 1.3 units at 400 mg Cu $kg^{-1}$ addition. Influences of Cu on each of these soil quality parameters were consistently greater than those of Cd. These effects were of a detrimental nature and large enough in most cases to significantly impact soil productivity. It is clear that new protocols are needed for evaluating potential effects of heavy metal loading of soils.

• The Korean Journal of Ecology
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• 제13권2호
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• pp.131-142
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• 1990

From July 1, 1985 to June 30, pH values of precipitation in Seoul area were average 5.1 and acid rain which was lower than pH 5.5 showed a frequence of 70.7%. Seasonal changes appeared in pH values of annual precipitation in Seoul. The pH patterns of spring and autumn were generally less acid than that of summer and winter, and snowfall pH was lower than rainfall. The beginning rainfall in Seoul was neutral because of alkali dust in the atmosphere. As times went on, rainfall pH was gradually low and after 1 to 2 hours, showed a steady state. On the surface soil precipitation was neutralized by soil buffering capacity.

• Asian-Australasian Journal of Animal Sciences
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• 제12권7호
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• pp.1104-1110
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• 1999

We condicted two experiments to evaluate the interaction among fumaric acid (FA), protected acids (PA), or no additional acid (NO) and two different levels of acid buffering capacity (BC) in diets for 14-d-old weaned pigs. BC was varied substituting mono-calcium phosphate and calcium sulfate for dicalcium phosphate and calcium carbonate. In the high BC diet plus PA, FA was also added. In Exp. 1, 48 gilts were raised for 31 days on the six diets, evaluating growth performance and fecal digestibility. In Exp. 2, 42 gilts were raised. With each diet three subjects were sacrificed after 19 days and four after 38 days. In addition, six subjects were sacrificed at weaning. Growth and carcass performance, ileal digestibility, bacterial populations and pH in the gut were assessed. The piglet performance and stomach, ileal and cecal pH, and empty body composition were not affected by the diets. Empty body composition other than ash content was affected by piglet age (p<0.01). The BC did not influence digestibility. The dietary inclusion of PA improved fecal digestibility of protein (p<0.05) compared to the addition of FA and NO. Ileal digestibility slightly increased with both acid additions (p<0.10), the groups receiving PA showing the higher values. Piglets fed diets with low BC had lower Lactobacillus and E. coli counts in the ileum (p=0.07) and higher Lactobacillus in the colon (p=0.08). Acidified diets tended to reduce E. coli counts in the ileum (p=0.10) and increased Lactobacillus in the colon (p=0.09). The addition in the diet of PA increased Lactobacillus in the ileum compared to the sole addition of free fumaric acid (p=0.07). The addition of protected acids, combined with free fumaric acid in the case of high BC diets, increased protein digestibility and Lactobacillus counts and reduced E.coli counts. Only some changes in the concentration of bacterial population can be expected with a diet of low BC.

• 대한임상검사과학회지
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• 제55권3호
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• pp.195-202
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• 2023

본 연구는 국내 시판중인 일부 어린이 음료의 우식활성능을 측정하여 치아우식의 위험도를 알아보아 치아우식증을 예방하기 위한 기초자료를 제공하고자 시행하였다. 실험음료는 국내 시판중인 탄산음료류, 과실음료류, 우유류, 발효유류 중에서 가장 시장점유율이 높은 음료를 선택하였고, 대조군으로는 0.25% glucose tryticase soy broth를 제조하여 사용하였다. 실험은 음료의 pH, 적정산과 완충력, 음료에 S. mutans를 접종한 후 시간 별로 산 생성력과 생활력을 측정하였다. 결과 어린이 음료의 pH는 탄산음료(2.61±0.02)가 가장 낮았고 적정산은 우유(14.00±0.58)가 가장 낮았다. 완충력이 높은 것은 발효유(80.33±3.64)이고, 탄산음료(9.40±1.06)가 가장 낮았다(P<0.05). 산 생성력 측정결과, 탄산음료(3시간 25분)가 가장 높았고 우유(4시간)가 가장 낮았다. 음료에 S. mutans를 접종하여 성장력 측정 결과, 우유는 계속적으로 증가하였다. 결론적으로 어린이 음료는 pH가 낮고 S. mutans의 산 생성력이 높으므로 어린이 음료 섭취 후 철저한 구강위생관리가 필요하다고 생각한다.

• 대한소아치과학회지
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• 제38권2호
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• pp.146-154
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• 2011

어린이용 시럽제의 우식유발능에 관해 알아보기 위하여 국내에서 시판 중인 일반의약품 어린이용 시럽제 8종에 대한 생체 외 연구를 사행하였다. 어린이용 시럽제 8종을 실험군으로 10% 자당을 양성 대조군, 인공 타액을 음성 대조군으로 하였다. 실험군 및 대조군의 pH를 측정하고 시료용액 20 ml의 pH를 7로 맞추는데 필요한 2 N NaOH의 부피로 완충능을 측정하였다. Ostwald 파이햇을 시료용액 2 ml가 통과하는데 걸린 시간을 측정하여 비점조도를 계산하였다. Streptococcus mutans의 배양액을 접종 후 48시간 배양하여 pH의 변화를 측정해서 산생성능을 살펴보았다. 하루에 3번 시료용액에 유치 법랑질 시편을 20분간 넣은 후 인공타액에 보관하는 pH 순환모텔을 5일간 적용하였고 표면미세정도의 변화를 측정하여 유치 법랑질 침식능을 검사하였다. 본 연구 결과로부터 어린이용 시럽제는 자체 산도 및 완충능, 점조도, 유치 법랑질 침식능에서 모두 우식유발 가능성이 높음을 알 수 있으며 산생성능에서도 3종를 제외한 어린이용 시럽제가 양성대조군보다 높게 나타남으로써 우식 유발가능성이 높음을보여준다.

• KSBB Journal
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• 제16권4호
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• pp.389-397
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• 2001

본 연구에서는 T. thiooxidans MET 균주를 이용하여 비소화 슬러지와 혐기성 소화슬러지로부터 중금속을 용출하여 제거하는데 영향을 미치는 슬러지 성상의 영향을 조사하였다. 슬러지 종류와 농도에 관계없이 슬러지로부터의 중금속 용출은 슬러지 용액의 pH에 의존하였다. 슬러지 용액의 pH가 3.0 이하일 때 효율적인 중금속 용출 효율을 얻을 수 있었으며, Zn > Cu > Cr의 순서로 용출이 진행되었다. 비소화 슬러지 및 혐기성 소화 슬러지간에 buffering capacity의 차이는 없었으나, 동일 고형물 농도에서 혐기성 소화 슬러지에서 T. thiooxidans MET의 황산화속도가 높기 때문에, 혐기성 소화 슬러지 용액의 pH 감소 속도가 비소화 슬러지보다 빨랐다. 그러나, pH 변화에 따른 슬러지 단위 질량당 중금속 용출량을 비교한 결과, 동일 pH 조건에서 혐기성 소화슬러지의 중금속 용출량은 비소화 슬러지에서의 중금속 용출량 보다 낮았다. 이는 혐기성 소화 슬러지와 비소화 슬러지에 함유되어 있는 불용성 금속화합물의 차이 때문으로 사료되었다. 슬러지 성상에 관계없이, 슬러지 고형물 농도가 증가할수록 (10~70 g/L) 중금속 용출 효율은 감소하였고, 최적 S$^{\circ}$/슬러지 고형물의 비율은 0.1이었다. 또한, T thiooxidans MET 균주를 이용한 슬러지로부터 중금속 용출 공정은 90% 이상의 살균 효과와 20% 정도의 슬러지 감량 효과가 있었다.

• 한국치위생학회지
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• 제20권3호
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• pp.387-397
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• 2020

Objectives: This study aimed to evaluate the inhibitory effects of probiotics containing Lactobacillus reuteri on Streptococcus mutans and Aggregatibacter actinomycetemcomitans. In addition, the degree of biofilm formation, initial acidity, buffering ability, and acid production performance were measured to confirm the dental caries-inducing ability. Methods: S. mutans (KCTC3065) and A. actinomycetemcomitans (KCTC2581) were used as experimental strains. The number of viable cells, degree of biofilm formation, initial pH, buffering capacity, and production performance were measured for comparing L. reuteri-containing probiotics and Bulgaris. Results: The viability of S. mutans in the groups was reduced in the following order: Bulgaris, probiotics, control. The degree of biofilm formation was significantly higher at 0% and gradually reduced at different concentrations (p<0.01). At 2.5%, the absorbance of the probiotics and Bulgaris groups differed significantly (p<0.01). The acid formation ability differed significantly based on the performance of S. mutans in each product (p<0.05). The absorbance of the probiotics group was significantly lower than that of the Bulgaris group (p<0.01). Conclusions: This study suggests that the use of L. reuteri-containing probiotics as an adjuvant for the prevention and decreasing of oral diseases may reduce their incidence, which can be considered one of the benefits of using probiotics.

• Corrosion Science and Technology
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• 제8권2호
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• pp.74-80
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• 2009

The high alkaline property in the concrete pore solution protects the embedded steel in concrete from corrosion due to aggressive ions attack. However, a continuous supply of those ions, in particular, chlorides altogether with a pH fall in electrochemical reaction on the steel surface eventually depassivate the steel to corrode. To mitigate chloride-induced corrosion in concrete structures, finely grained mineral admixtures, for example, pulverized fuel ash (PFA), ground granulated blast furnace slag (GGBS) and silica fume (SF) have been often advised to replace ordinary Portland cement (OPC) partially as binder. A consistent assessment of those partial replacements has been rarely performed with respect to the resistance of each binder to corrosion, although the studies for each binder were extensively looked into in a way of measuring the corrosion rate, influence of microstructure or chemistry of chlorides ions with cement hydrations. The paper studies the behavior of steel corrosion, chloride transport, pore structure and buffering capacity of those cementitious binders. The corrosion rate of steel in mortars of OPC, 30% PFA, 60% GGBS and 10% SF respectively, with chloride in cast ranging from 0.0 to 3.0% by weight of binder was measured at 7, 28 and 150 days to determine the chloride threshold level and the rate of corrosion propagation, using the anodic polarization technique. Mercury intrusion porosimetry was also applied to cement pastes of each binder at 7 and 28 days to ensure the development of pore structure. Finally, the release rate of bound chlorides (i.e. buffering capacity) was measured at 150 days. The chloride threshold level was determined assuming that the corrosion rate is beyond 1-2 mA/$m^3$ at corrosion and the order of the level was OPC > 10% SF > 60% GGBS > 30% PFA. Mercury intrusion porosimetry showed that 10% SF paste produced the most dense pore structure, followed by 60% GGBS, 30% PFA and OPC pastes, respectively. It was found that OPC itself is beneficial in resisting to corrosion initiation, but use of pozzolanic materials as binders shows more resistance to chloride transport into concrete, thus delay the onset of corrosion.

• 한국환경농학회지
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• 제25권2호
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• pp.157-163
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• 2006

Investigation of Cd and Zn availability in four different soils as affected by the interactions of these two heavy metals was conducted using the metal desorption quantity-intensity (Q/I) isotherms. The soils were artificially contaminated with proper concentrations of Cd and Zn as $CdSO_4\;and\;ZnSO_4$ solutions. DTPA (diethylene triamine pentaacetic acid) - extractable and water-extiactable Cd or Zn from the soils were used as $Q_{Cd}\;or\;Q_{Zn}\;and\;I_{Cd}\;or\;I_{Zn}$ factors, respectively. The coefficient of determination for Cd and Zn desorption Q/I linear regression in the soils ranged from 0.947 to 0.999, which indicated that Q and I factors were closely correlated. The buffering capacity of Cd, $BC_{Cd}$, in the soils decreased with increasing Zn treatments, and the $BC_{Cd}$ values were ranged between 205.8 and 2255.6. The decreases of $BC_{Cd}$ values were mainly dependent upon the increases of $I_{Cd}$ factors. However, Zn buffering capacity. $BC_{Zn}$ decreased with increasing Cd treatments in acidic soils, and increased in neutral and calcareous alkaline soils. The $BC_{Cd}$ values were ranged from 143.2 to 6158.0. The values of $BC_{Zn}$ as influenced by the treatments of Cd were also controlled by the solubility of water-extractable Zn, $I_{Zn}$ factor. The solubility of water-extractable Cd and Zn was significantly dependent upon the changes of soil pH that were impacted by the treatment of Zn and Cd, respectively. Also, the availability of Cd was higher than Zn availability in the acidic and neutral soils, but Zn was higher than Cd in the calcareous alkaline soil.

• 한국토양환경학회지
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• 제1권2호
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• pp.15-21
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• 1996

산성강하물이 단기간에 걸쳐 지표수의 산성화에 미치는 영향을 조사하기 위하여 1995년 5월부터 10월까지 외부오염원이 거의 없는 강원도 춘천시에 위치한 저수지를 선정하여 연구를 수행하였다. 연구지역 일대의 지질을 조사하고 산골짜기에서 저수지로 흐르는 작고 얕은 하천의 수질을 분석하였다. 강우량은 우량계를 이용하여 측정하였고 강하물은 자동포집기를 이용하여 포집하였다. 연구기간동안의 강우의 pH 범위는 3.81~5.77로 평균 4.8을 나타내었으며 전기전도도 (EC)는 5~1.89$\mu$S/cm로 평균 10.6$\mu$S/cm를 나타냈다. 음이온 중에서는 ${SO_4}^{2-}$의 강하량이 3,119.7 kg/$\textrm{km}^2$로 가장 많았고, 양이온 중에서는 $NH^{4+}$가 1,053.2 kg/$\textrm{km}^2$로 가장 많았다. 지표수의 pH는 중성 또는 약염기성으로 강우의 pH가 산성이었음에도 지표수의 산성화 현상은 관찰되지 않았다. 그러나 골짜기에서 흐르는 하천수를 측정할 때마다 측정지점의 고도가 낮아질 수록 pH 값은 증가하는 경향을 나타내어 물이 하류로 흘러가는 동안에 일어난 산성 또는 염기성물질로 인한 산염기반응의 영향을 보여주었다. 이 결과는 토양의 완충능력과 모암내에서의 중화능력을 각각 구별하여 조사할 필요성을 제시하였다.