• 한국환경과학회지
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• 제10권2호
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• pp.119-127
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• 2001

The Keum river is one of the important river in Korea and has a drainage area of 9,873$\textrm{km}^2$. The Keum river is deepening pollution state due to development of the lower city and construction of a industrial complex. The water quality of the Keum river come to eutrophication state and belong to III grade of water quality standard. The concentration BOD in river is affected by the organic loading from a tributary and the algae biomass that largely happen to under eutrophication state. In the eutrophic water mass such as the Keum river, the autochthonous BOD was very important part for making a decision of water quality management, because it was accounted for majority of the total BOD. The purpose of this study was to survey the chatacteristics of water quality in summer and to estimate reaction coefficient. Also, we studied to correlationship between chlorophyll a and BOD(COD) for estimation of the autochthonous BOD. The correlationship between chlorophyll a and BOD(COD) were obtained through the culture experiment of phytoplankton in the laboratory. The results of this study may be summarized as follows ; The characteristics of water quality in summer were belong to III~IV grade of water quality standard as BOD and nutritive condition is very high. The BOD, ammonia nitrogen and phosphate loadings in Miho stream which inflowing untreated sewage from Chungju city was occupied with 64.07%, 26.36%, 46.08%, respectively. Maximum nutrient uptake (Vmax) was 0.4400$\mu$M/hr as substrate of ammonia nitrogen, 0.1652$\mu$M/hr as substrate of phosphate. Maximum specific growth rate ($\mu$max) was 1.2525$hr^{-1}$ as substrate of ammonia nitrogen, 1.5177$hr^{-1}$ as substrate of phosphate. The correlation coefficient between chlorophyll a and BOD by the culture experiment were found to be 0.911~0.935 and 0.942~0.947 in the case adding nutrient and no adding nutrient, respectively. The correlation coefficient between chlorophyll a and COD through the culture experiment were found to be 0.918~0.977 and 0.880~0.931 in the case adding nutrient and no adding nutrient, respectively. The autochthonous BOD(COD) was estimated to the relationship between BOD(COD) and chlorophyll a. The regression equation were found to be autochthonous BOD=(0.045~0.073)${\times}chlorophyll$ a and autochthonous $COD=(0.137~0.182){\times}chlorophyll$ a.

• 한국환경과학회지
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• 제3권3호
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• pp.185-195
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• 1994

Masan bay is one of the polluted enclosed bays, which has red tides problem and the formation of oxygen deficient water in the bottom layer. Most important factors that cause eutrophication and red tide is nutrient materials containing nitrogen and phosphorus which stem from terrestrial sources and nutrients released from sediment. Therefore, to improve of water quality, reduction of these nutrient loads should be indispensible. At this study, the three-dimensional numerical hydrodynamic and eutrophication model, which were developed by Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the phytoplankton production and also to evaluate the effect of water quality improvement plans on phytoplankton production. In field sorvey, the range of concentrations of chlorophyll-a at surface area was found to be 29.17 - 212.5mg/m3, which were exceeding eutrophication criteria. The constant currents defined by integrating the simulated tidal currents over 1 tidal cycle showed the counterclockwise eddies in the southern part of Budo. The general directions of constant currents were found to be southward at surface and northward at bottom over all the bay. The eutrophication model was calibrated with the data surveyed in the field area in June, 1993. The calculated results are in fairly good agreement with values within relative error of 30%. The pollutant load from the sources such as the input from terrestrial release from the sediment was reduced by the rate of 50, 70, 90, 98% to effect of phytoplankton production. Phytoplankton production was reduced to of the 90% reduction of the input loads from terrestrial sources and 8% in 90% reduction of the load from sediment.

• 한국환경농학회지
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• 제27권4호
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• pp.343-348
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• 2008

시설재배 토마토(To) 생산에 미치는 녹비 토양투입 효과와 양분 수지량을 조사하기 위하여 겨울과 여름 휴한기 동안 헤어리베치(Hv), 호밀(Ry), 콩(Sb), 수단그라스(Sd)를 녹비로 재배하였으며, 녹비와 토마토를 조합한 작부체계로서 두과 녹비작물을 활용한 Hv-To-Sb-To, 화본과 녹비작물로 구성된 Ry-To-Sb-To, 그리고 두과와 화본과 녹비를 교호 재배하는 Ry-To-Sd-To로 구분하여, 화학비료(Cf)를 처리하는 Cf-To-Cf-To 작부체계와 비교하였다. 녹비 수량은 겨울 휴한기에 비해 여름 휴한기 동안 높았던 반면, 녹비의 질소 고정량은 화본과에 비해 두과 녹비작물에서 현저히 높아 두과 녹비작물의 경우 토마토 재배를 위한 질소량의 62%를 고정하였다. 두과 녹비작물로 구성된 작부체계(Hv-To-Sb-To)의 토마토 수량은 관행(Cf-To-Cf-To)과 유사하였으나, 화본과 녹비로 구성된 처리구(Ry-To-Sd-To)의 수량은 두과 녹비작물 처리구 수량의 40% 수준으로서 현저한 수량 감소가 나타났다. 한편 두과 녹비작물 활용에 따른 질소공급 효과로 인해 토마토 생육 및 과실 생산량은 증가한 반면, 후작물에 의한 양분흡수량이 많아 Ry-To-Sb-To 작부체계의 N:P:K 수지량은 -80:-59:$-480\;kg\;ha^{-1}\;yr^{-1}$로서 양분의 불균형이 심각하였다. 역으로 화본과 녹비로 구성된 Ry-To-Sb-To 작부체계의 N:P:K 수지량은 43:1:$130\;kg\;ha^{-1}\;yr^{-1}$로서 양분수지상 3요소 모두 양의 값을 보였으나, 이는 화본과 녹비작물의 낮은 질소 고정량과 높은 C/N율로 인해 후작물 토마토의 생육이 부진하였던 결과로 판단된다. 결론적으로 두과 녹비작물 토양 환원시 양분 수지량에서 큰 음의 값을 보였을지라도 관행수준의 토마토 수량을 얻을 수 있다는 관점에서 두과녹비는 화학비료 없이 유기농 재배를 위한 양분공급 및 토양지력 증진 방안으로서 활용 가능하고, 일반 토마토 재배 시에도 다소의 부족한 양분 수지량만 조정한다면 균형된 작부체계로 이용할 수 있을 것으로 판단된다.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.87-92
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• 2013

미세조류는 바이오연료를 생산하기 위해 필요한 성분인 지방질의 생산성이 우수하기 때문에 바이오연료의 유망한 원료로서 최근 많은 주목을 받고 있다. 본 연구에서는, 이러한 미세조류의 성장 속도와 미세조류 내부의 지방의 함량이 최대가 되도록 하기 위한 목적으로, 미세조류의 성장과 지방의 생성을 설명하는 제일원리(first principle)에 근거한 상미분방정식(ODE) 모델에 대하여 조사하였다. 모델은 6개의 상태변수와 12개의 파라미터로 이루어져 있으며, 미세조류의 성장을 영양분의 흡수와 흡수된 영양분에 의한 성장으로 두 단계로 나누어 설명한 Droop 모델의 가정을 따른다. 본 연구에서는 민감도 분석(Sensitivity analysis)을 위한 최대의 정보를 줄 수 있는 입력 신호를 결정하기 위해 D-optimality criterion을 이용한 최적 입력 설계(Optimal input design)를 수행하였으며, 구하여진 입력 신호를 적용하여 민감도 분석을 수행하여 모델에 좀 더 중요한 파라미터를 결정하였다. 또한 미세조류의 성장속도와 지방의 함량이 최대가 되도록 하기 위하여 모델 예측 제어(MPC)를 수행하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권3호
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• pp.423-431
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• 2001

Animals are one of the important memberships of the food chain. The low-efficiency rule of nutrient transfer from one member to the next in the food chain determines the low efficiency of animal agriculture for human food. On the average, about 20% feed proteins and 15% feed energy can be converted into edible nutrients for humans. The rest proportion of feed nutrients is exposed to the environment. Environmental pollution, therefore, is inevitable as animal agriculture grows intensively and extensively. The over-loading of the environment by nutrients such as nitrogen, phosphorus from animal manure results in soil and water spoilage. The emission of gases like $CH_2$, $CO_2$, $SO_2$, NO, $NO_2$ by animals are one of the contributors for the acidification of the environment and global warming. The inefficient utilization of natural resources and the probable unsafety of animal products to human health are also a critical environmental issue. Improving the conversion efficiency of nutrients in the food chain is the fundamental strategy for solving environmental issues. Specifically in animal agriculture, the strategy includes the improvements of animal genotypes, nutritional and feeding management, animal health, housing systems and waste disposal programs. Animal nutrition science plays a unique and irreplaceable role in the control of nutrient input and output in either products or wastes. Several nutritional methods are proved to be effective in alleviating environmental pollution. A lot of nutritional issues, however, remain to be further researched for the science of animal nutrition to be a strong helper for sustainability of animal agriculture.

• 한국농공학회지
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• 제39권2호
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• pp.53-61
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• 1997

The interface system, GIS-AGNPS was to be validated with field data from six tested small watersheds ranging from 0.7 to 4.7$km^2$ in size which have steep topography and complex landuses. The model validation involved the calibration of input parameters and component modifications, in efforts to develop a model applicable to general uses for identifying and controlling nonpoint source pollution loads from agricultural watersheds. The simulated direct runoff from AGNPS was in good agreement with the field data for the averaged antecedent moisture conditions or AMC- II. The results differed, however, from the observed for AMC- I or III. A simple empirical relationship was proposed to estimate the curve number for AMC- I or m from AMC- II, which was found to result in simulated runoff close to the observed. The peak runoff relationship at AGNPS was also modified to reflect the watershed conditions and tested satisfactorily with the field data. The simulated sediment yields from the watersheds were fair as compared to the observed. Nutrient loads simulated from the model were different from the observed data. It appeared that the model was incapable of adequate depicting nutrient transport processes at paddy field and other landuses of the tested watersheds. Some modifications may be needed for the accurate representing the processes at paddy field.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.81-89
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• 2020

In the forest ecosystems, litterfall is an important component of the nutrient cycle that regulates the accumulation of soil organic matter (SOM), the input and output of the nutrients, nutrient replenishment, biodiversity conservation, and other ecosystem functions. Therefore, a profound understanding of the major processes (litterfall production and its decomposition rate) in the cycle is vital for sustainable forest management (SFM). Despite these facts, there is still a limited knowledge in tropical forest ecosystems, and further researches are highly needed. This shortfall of research-based knowledge, especially in tropical forest ecosystems, may be a contributing factor to the lack of understanding of the role of plant litter in the forest ecosystem function for sustainable forest management, particularly in the tropical forest landscapes. Therefore, in this paper, I review the role of plant litter in tropical forest ecosystems with the aims of assessing the importance of plant litter in forest ecosystems for the biogeochemical cycle. Then, the major factors that affect the plant litter production and decomposition were identified, which could direct and contribute to future research. The small set of studies reviewed in this paper demonstrated the potential of plant litter to improve the biogeochemical cycle and nutrients in the forest ecosystems. However, further researches are needed particularly on the effect of species, forest structures, seasons, and climate factors on the plant litter production and decomposition in various types of forest ecosystems.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.63-68
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• 2007

Litter production, nutrient contents of each component of litterfall and amount of nutrients returned to forest floor via litterfall were investigated from May 2005 through April 2006 in Quercus mongolica, Quercus variabilis and Pinus densiflora forests at Mt. Worak National Park. Total amount of litterfall during one year in Q. mongolica, Q. variabilis and P. densiflora forests was 542.7, 459.2 and $306.9\;g\;m^{-2}\;yr^{-1}$, respectively. Of the total litterfall, leaf litter, branch and bark, reproductive organ and the others occupied 50.3%, 22.7%, 10.1 % and 16.9% in Q. mongolica forest, 81.9%, 7.2%, 3.1% and 7.9% in Q. variabilis forest, 57.4%, 12.8%, 5.6% and 24.1 % in P. densiflora forest, respectively. Nutrients concentrations in oak litterfall were higher than those in needle litter. N, P, K, Ca and Mg concentration in leaf litterfall were 13.8, 1.1, 7.2, 4.2 and 1.3 mg/g for Q. mongolica forest, 10.5, 0.7, 3.2, 3.7 and 1.6 mg/g for Q. variabilis forest, 5.3, 0.4, 1.2, 2.8 and 0.6mg/g for P. densiflora forest, respectively. The amount of annual input of N, P, K, Ca and Mg to the forest floor via litterfall was 43.36, 2.89, 21.38, 23.31 and $5.62\;kg\;ha^{-1}\;yr^{-1}$ for Q. mongolica forest, 32.28, 2.01, 10.23, 20.29 and $7.78\;kg\;ha^{-1}\;yr^{-1}$ for Q. variabilis forest, 15.80, 1.04, 3.99, 9.70 and $2.10\;kg\;ha^{-1}\;yr^{-1}$ for P. densiflora forest, respectively.

• 한국환경과학회지
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• 제18권9호
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• pp.1027-1033
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• 2009

For the assesment of pollutant loads, a monitoring has been conducted to identify hydrologic conditions and water quality of the Oenam watershed in Juam Lake, and the SWAT model integrated with GIS was applied to the watershed and evaluated for its applicability through calibration and verification using observed data. For the model application, digital maps were constructed for watershed boundary, land-use, soil series, digital elevation, and topographic input data of the Oenam watershed using Arcview. The observed runoff was 832.8 mm while the simulated runoff was 842.8 mm in 2003. The model results showed that the simulated runoff was in a good agreement with the observed data and indicated reasonable applicability of the model. In terms of nutrient load, the simulation results of T-N, T-P showed a similar trend to observed values. The observed T-N load was 10.8 kg/ha and the simulated T-N load was 7.6 kg/ha while the observed T-P load was 0.21 kg/ha and the simulated T-P load was 0.18 kg/ha. In general, SWAT model predicted observed runoff and loads of T-N and T-P after calibration with observed data in acceptable range. Overall, SWAT model was satisfactory in estimation of nutrient pollutant loads of the rural watershed.

• 한국해양학회지:바다
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• 제19권1호
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• pp.41-52
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• 2014

반폐쇄적인 천수만에서 장마기 동안 짧은 기간에 대량의 담수가 집중적으로 유입될 때 발생할 수 있는 플랑크톤 생태계의 영향을 파악하고자 하였다. 이를 위해 장마기 전 후, 2012년 6월 27일부터 9월 1일까지 약 열흘 간격으로 수온, 염분, chlorophyll a 농도, 영양염 농도와 동물플랑크톤의 분포를 조사하여, 이들 각 변수간의 관계를 파악해 보았다. 담수 방류 후 영양염 농도는 약 2배 이상 증가하였고, 그 결과로 나타나는 chlorophyll a 농도 증가는 수 일이 소요되는 것으로 추정되었다. 동물플랑크톤의 경우는 먹이생물인 식물플랑크톤의 증가에 따른 개체수 증가라는 긍정적인 면과 염분 충격으로 인한 사망이라는 부정적인 면이 동시에 나타나는 것으로 여겨졌다. 급격한 염분 하강으로 인한 동물플랑크톤의 사망률은 최고 40%까지 나타났으나, 사체의 빠른 침강으로 신뢰할 만한 사망률 추정에는 한계가 있었다.