• ALGAE
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• 제34권3호
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• pp.237-251
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• 2019

The dinoflagellate genus Alexandrium is known to often form harmful algal blooms causing human illness and large-scale mortality of marine organisms. Therefore, the population dynamics of Alexandrium species are of primary concern to scientists and aquaculture farmers. The growth rate of the Alexandrium species is the most important parameter in prediction models and nutrient conditions are critical parameters affecting the growth of phototrophic species. In Korean coastal waters, Alexandrium affine and Alexandrium fraterculus, of similar sizes, often form red-tide patches together. Thus, to understand bloom dynamics of A. affine and A. fraterculus, growth rates and nitrate uptake of each species as a function of nitrate ($NO_3$) concentration at $100{\mu}mol\;photons\;m^{-2}s^{-1}$ under 14-h light : 10-h dark and continuous light conditions were determined using a nutrient repletion method. With increasing $NO_3$ concentration, growth rates and $NO_3$ uptake of A. affine or A. fraterculus increased, but became saturated. Under light : dark conditions, the maximum growth rates of A. affine and A. fraterculus were 0.45 and $0.42d^{-1}$, respectively. However, under continuous light conditions, the maximum growth rate of A. affine slightly increased to $0.46d^{-1}$, but that of A. fraterculus largely decreased. Furthermore, the maximum nitrate uptake of A. affine and A. fraterculus under light : dark conditions were 12.9 and $30.1pM\;cell^{-1}d^{-1}$, respectively. The maximum nitrate uptake of A. affine under continuous light conditions was $16.4pM\;cell^{-1}d^{-1}$. Thus, A. affine and A. fraterculus have similar maximum growth rates at the given $NO_3$ concentration ranges, but they have different maximum nitrate uptake rates. A. affine may have a higher conversion rate of $NO_3$ to body nitrogen than A. fraterculus. Moreover, a longer exposure time to the light may confer an advantage to A. affine over A. fraterculus.

• Journal of Radiation Protection and Research
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• 제32권2호
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• pp.45-50
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• 2007

본 연구는 한국인 특성에 대해 보다 신뢰할 수 있는 방사성핵종의 체내 흡수선량 평가를 위한 일환으로 $^{131}I$을 선정하여 체내 각 장기별 잔류율 및 소변 일일배설률을 측정하였다. 실험방법은 성인남성 28명을 대상으로 $^{131}I$을 경구 투여한 후, 시간대별(2, 4, 6, 24시간) 갑상선, 간, 위, 소장, 신장, 소변의 방사능을 측정하고 이를 이용하여 각 장기별 잔류율 및 소변 일일배설률을 산출하였다. 그 결과, $^{131}I$ 투여 24시간 후 갑상선이 평균 19.70%의 잔류율과 71.12%의 소변 일일배설률을 나타냈으며, 갑상선을 제외한 각 장기는 투여 2시간 후 최고 잔류율 및 최고 소변 일일배설률을 보이나, 이후 감소하는 경향을 보였다. 또한 잔류율이 높은 장기 순서는 갑상선을 제외하고 위, 왼쪽 신장, 간, 소장, 오른쪽 신장으로 나타났다. 본 연구를 통해 산출된 방사성옥소의 섭취 24시간 후 갑상선 잔류율 변화는 기존 30%로 보고된 ICRP-54/67 및 25% 잔류율로 보고된 ICRP-78의 자료와 차이를 나타냈다. 한국인의 특성에 맞는 체내 흡수선량 평가의 올바른 접근과 그에 따른 기초 자료의 확보는 향후 원자력 발전소의 작업 종사자 내부피폭 및 임상에서 발생 가능한 체내 피폭의 정량적 평가에 도움을 줄 수 있을 것으로 판단된다.

• 대한수의학회지
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• 제6권1호
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• pp.24-30
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• 1966

In order to observe the effect of the injected radioactive iodine-$I^{131}$ on the uptake in thyroid of normal male guinea pigs and P.B.$I^{131}$ conversion ratio of $I^{131}$ in serum, 24 matured male guinea pigs were divided in 4 groups and $35{\mu}c$, $70{\mu}c$, $140{\mu}c$ and $280{\mu}c$ per kg of body weight respectively were injected subcutaneously. 1. The uptake rates of radioactveiodine-$I^{131}$ by external counts of thyroidal uptake reached the maximum level of uptake in 24 hours after injection. 2. As the injected amount increases, the uptake rates of maximum levels and release rate were increased. 3. Uptake rate in the removed thyroid have shown no statistical in the $35{\mu}c$ and $70{\mu}c$ groups of injected guinea pigs. 4. There was no statistical significance in $140{\mu}c$ and $280{\mu}c$ groups of injected guinea pigs. 5. P.B.$I^{131}$ conversion ratio of $I^{131}$ in serum was not in proportion to injected amounts: 61.0%(35), 70.2%(70), 75.3%(140) and 64.8%(280).

• ALGAE
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• 제25권1호
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• pp.17-26
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• 2010

The effects of salinity on various ecophysiological parameters of Ulva pertusa such as growth, nutrient uptake, photosynthetic performance and internal nutrient composition were tested. U. pertusa was collected from an eelgrass bed in a semi-protected embayment on the southwest coast of Korea. Under salinity regimes from 5 to 40 psu, the specific growth rates $(\mu)$ of U. pertusa ranged from 0.019 to $0.032\;d^{-1}$. Maximum growth rate was observed at 20 psu, and minimum at 40 psu. This species showed various uptake rates for nitrate and phosphate. Nutrient uptake was noticeably higher at intermediate salinity levels, and lower at both extremes. Salinity significantly influenced chlorophyll-$\alpha$ content and effective quantum yield. Tissue nitrogen content ranged from 1.5 to 2.9% N (dry weight), whereas tissue phosphorus ranged from 0.1 to 0.14% P (dry weight). The N : P ratio in the tissue of U. pertusa was considerably higher, ranging from 30 to 50. Increased growth at lower salinity suggests that the initial growth rate of U. pertusa is greater during the rainy season (i.e., late spring and early summer) than any other season during the year. The appearance of an Ulva bloom in eelgrass beds may be triggered by salinity more than by other environmental factors such as light and temperature.

• 해양환경안전학회지
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• 제27권5호
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• pp.630-638
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• 2021

본 연구에서는 와편모조류 Alexandrium affine(LIMS-PS-2345)의 생장에 미치는 용존태 무기 및 유기 영양염의 영향을 조사하였다. 영양염 흡수 동력학 실험에서 A. affine의 최대흡수속도(ρ_max)와 반포화상수(Ks)는 질산염에서 77.0 pmol/cell/hr과 17.6 μM, 인산염에서 15.5 pmol/cell/hr과 3.88 μM로 산출되어, 무기영양염에 대하여 높은 요구량 및 낮은 친화성을 가지고 있는 것으로 나타났다. 유기 영양염에 따른 A. affine의 생장속도를 확인한 결과, 유기 질소 urea, glycine와 유기 인 adenosine triphosphate(ATP), glycerol phosphate(Glycerol-P) 첨가구에서 무기 영양염 첨가구의 70 % 이상 생장속도를 보였다. 따라서 낮은 무기 영양염 환경에서 A. affine의 우점화와 종간경쟁에서 우위를 위해서는 용존태 유기 영양염의 이용이 필요할 것으로 생각된다.

• Journal of Plant Biology
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• 제13권1호
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• pp.25-32
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• 1970

Ecological study on the reclaimed high saline soil was carried out throughout a year(1969) to elucidate the changes of the structure of halophytes communiteis and the possibilities of desalination from high saline soil by absorption of chloride ion. Results from this studies are summarized as followings; 1) The growth rates of halophytes showed a variation; maximum growth rate of Salicornia appeared on August, Chenopodium on July, Suaeda on July, Aster on August and Scirpus on June. 2) Changes of frequency of each halophyte were varied in accordance with species. Chenopodium and Salicornia have the highest frequency of all on May. However, frequency as well as density of halophytes decreased after on May due to competition for absorbing moisture in plant communities. 3) The terrestrial plants which were succeed into the reclaimed tidal land had herborized 25 species on the both side of irrigation route. 4) Each of the maximum chloride uptake by halophytes appeared on May(Salicornia and Aster), on June(Chenopodium and Scirpus), and on August(Suaeda), respectirecely 5) Among the halophytes, Salicornia was confirmed to absorb the highest amount of chloride. A possible amount of chloride uptake by all halophytes per 100 square cm reached about 24,629. ppm.

• Journal of Ginseng Research
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• 제44권4호
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• pp.627-636
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• 2020

Background: Cultivation of medicinal crops, which synthesize hundreds of substances for curative functions, was focused on the synthesis of secondary metabolites rather than biomass accumulation. Nutrition is an important restrict factor for plant growth and secondary metabolites, but little attention has been given to the plasticity of nutrient uptake and secondary metabolites synthesis response to soil nitrogen (N) change. Methods: Two year-field experiments of Sanqi (Panax notoginseng), which can synthesize a high level of saponin in cells, were conducted to study the effects of N application on the temporal dynamics of biomass, nutrient absorption, root architecture and the relationships between these parameters and saponin synthesis. Results: Increasing N fertilizer rates could improve the dry matter yields and nutrient absorption ability through increasing the maximum daily growth (or nutrient uptake) rate. Under suitable N level (225 kg/ha N), Sanqi restricted the root length and surface and enhanced the root diameter and N uptake rate per root length (NURI) to promote nutrient absorption, but the opposite status of Sanqi root architecture and NURI was found when soil N was deficient. Furthermore, increasing N rates could promote the accumulation of saponin in roots through improving the NURI, which showed a significant positive relationship with the content of saponin in the taproots. Conclusion: Appropriate N fertilizer rates could optimize both root architecture and nutrient uptake efficiency, then promote both the accumulation of dry matter and the synthesis of saponins.

• Journal of Forest and Environmental Science
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• 제39권3호
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• pp.119-127
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• 2023

In this study, quantitative models were applied to case parks to estimate the carbon reduction by trees, which was compared and analyzed at the tree and park levels. At the tree level, quantitative models of carbon storage and uptake differed by up to 7.9 times, even for the same species and size. At the park level, the carbon reduction from quantitative models varied by up to 3.7 times for the same park. In other words, carbon reduction by quantitative models exhibited considerable variation at the tree and park levels. These differences are likely due to the use of different growth environment coefficients and annual diameter at breast height growth rates and the overestimation of carbon reduction due to the substitution of the same genus and group model for each tree species. Extending the annual carbon uptake per unit area of the case park to the total park area of Chuncheon a carbon uptake ranging from a minimum of 370.4 t/yr and a maximum of 929.3 t/yr, and the difference can reach up to 558.9 t/yr. This is equivalent to the carbon emissions from the annual household electricity consumption of approximately 2,430 people. These results suggest that the indiscriminate application of quantitative models to estimate carbon reduction in urban trees can lead to significant errors and deviations in estimating carbon storage and uptake in urban greenspaces. The findings of this study can serve as a basis for estimating carbon reduction in urban greening research, projects, and policies.

• 대한화학회지
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• 제27권1호
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• pp.31-37
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• 1983

실험실 조건에서 몇 개의 다른 종류의 토양에 의한 일산화탄소 소모를 측정했다. 시료로는 유기질이 많은 부식토 및 도로변의 토양과 실험에서 이미 사용한 높은 농도의 일산화탄소와 접했던 부식토 및 도로변의 토양을 택했다. 높은 CO농도 조건에서 CO의 소모성을 조사하기 위해서 18.2l 반응용기에서 CO의 농도를 2,000ppm에서 24,000ppm으로 변화시켰다. 토양의 CO 제거는 기체크로마토그래피법으로 측정하였다. 본 실험에서 시행한 조절실험의 결과를 보면 CO를 주로 제거하는 것은 화분용 토양임을 지적하고 있다. 부식토의 CO소모속도는 도로변의 흙에 비하여 월등히 크고, 실험에서 재사용된 부식토는 새로운 부식토에 비하여 약 15% 높은 소모속도를 나타냈다. 대기로부터 CO를 제거하는 토양의 능력은 $9,000{\sim}24,000ppm$의 CO농도 범위에서는 13,000ppm 근처일때 최대치에 도달했다. 스트렙토마이신의 첨가는 토양의 CO제거능력에 큰 영향을 미치지 못하지만, 10%의 소금물은 부식토의 CO제거능력을 현저하게 억제시켰다.

• 한국환경과학회지
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• 제12권8호
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• pp.853-860
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• 2003

Plants sequester atmospheric CO$_2$, a major agent of climate change, during the growing periods and mitigate its rising accumulation in the atmosphere. Pinus densiflora and Quercus mongolica are the native tree species dominant in the temperate forests of Korea. This study quantified the annual CO$_2$ uptake by the two species at forest sites in Chuncheon in the middle of the country. The quantification was based on seasonal measurements of CO$_2$ exchange rates under natural conditions by an infrared gas analyzer over the growing season (1999). The monthly CO$_2$ uptake per unit leaf area ranged from 1.6-6.7 mg/d㎡/h for P. densiflora and from 3.7-8.9 mg/d㎡/h for Q. mongolica, with a maximum in mid-summer. An equation for each species was generated to estimate easily the annual CO$_2$ uptake by total leaf area per tree, which subtracted the CO$_2$ release (i.e. respiration) by leaves and woody organs from the gross CO$_2$ uptake (diurnal uptake and release by leaves). Annual CO$_2$ release by leaves and woody organs accounted for 58-73％ of the gross CO$_2$ uptake across tree specimens. Annual CO$_2$ uptake per tree increased with increasing dbh (stem diameter at breast height) for the study diameter range, and was greater for Q. mongolica than for P. densiflora in the same dbh sizes. This was mainly associated with a greater total leaf area in the former. For example, the annual CO$_2$ uptake by one tree with dbh of 25 cm was 35.6 kg/yr for P. densiflora and 47.9 kg/yr for Q. mongolica. The results from this study can be applied to evaluate an atmospheric CO$_2$ reduction of woody plants by forest type and age class.