• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.26-26
• /
• 2017

우리나라는 하천 및 호수 등 지표수에 대한 수자원 의존도가 매우 높다. 지표수는 태양광에 노출되어 있고, 기온의 영향을 직접 받기 때문에 기후변화에 대해 매우 민감한 수체이다. 기후변화로 인한 이상 저온, 이상 고온, 홍수, 가뭄 등의 자연 현상은 하천, 호수의 물리화학적 및 생태학적 특성을 변화(교란)시키고 있다. 이러한 기상현상에 변동되는 수질특성을 고려하여 기상청 확률기상예보를 구축된 인공신경망 예측모형의 입력인자로 적용하여 수질예보시스템을 개발하고자 하였다. 모형구축은 실제 일어난 기상관측자료와 요인분석을 통해 분류한 수질인자를 반영하여 단위유역별 수질예측을 위한 ANN학습을 실시하였다. 각 단위유역마다 기상요인의 공간적 세밀화 적용을 위해 각각 남강A, 남강B는 산청기상대, 남강C, 남강D는 진주기상대, 남강E는 의령기상대 자료를 이용하였으며, 수질항목은 DO, BOD, COD, TOC, T-P, SS 총 6개로 단위유역 5개에서 총 30개 예측모형 구축을 위한 자료를 수집하였다. 학습된 인공신경망 예측모형에 기상청 확률예보 값을 입력인자로 사용하여 모형평가를 실시하였다. 5개 단위유역 중 상대적으로 유역관리의 시급성을 고려하여 남강댐 하류 단위유역인 남강D, 남강E 인공신경망 모형의 입력자료로 적용하여 평가하였다.

• Korean Journal of Ecology and Environment
• /
• v.34 no.1 s.93
• /
• pp.9-19
• /
• 2001

contrasting monsoon between 1993 and 1994 produced an interannual difference in hydrology. Theoretical water residence time (TWRT) in monsoon 1993 averaged 27 d, which was>3 months shorter compared to the TWRT in monsoon 1994. A dominant physical process influencing thermal stratification, water movement, and mixing regime was an interflow current in 1993. During summer 1993, river water plunged to mid-lake (location 27 km) and passed through the 10${\sim}$20m stratum of the reservoir, resulting in an isolation of epilimnetic lake water from advected river water. The interflow disrupted thermal stratification and produced a meta-hypolimnetic warming of >4$^{\circ}C$ downlake, thereby increased a mixing depth (>13 m). In contrast, during monsoon 1994 density currents were not observed and strong thermal stratification occurred in the entire reservoir, resulting in > 2 fold greater thermal resistance (8.2${\times}10^{5}$ erg)compared to 1993 (4.0${\times}10^{5}$ erg). This reservoir was identified as a typical warm monomictic reservoir which showed one mixis during early winter. The timing of overturn, however, differed between the two years as a result of distinct contrast in TWRT and thermal regime; overturn in 1993 occured about one month earlier relative to that in 1994. Hypolimnetic warming was predictable in this system; the variation in discharge accounted (Y = 4.35-0.06X+0.10X$^{2}$, p<0.0001)for 98% of the interannual variation in hypolimnetic temperature. Overall data suggest that thermal stability, the timing of fall overturn, and water residence time in this system are primarily regulated by the intensity of monsoon.

• Korean Journal of Ecology and Environment
• /
• v.45 no.2
• /
• pp.174-189
• /
• 2012

The objective of this study was to determine the weight-length relations and condition factor (K) of Zacco platypus, along the trophic gradients from oligotrophic to eutrophic state in six reservoir ecosystems ($B_aR$, $Y_yR$, $J_yR$, $G_pR$, $Y_dR$, and $M_sR$), during 2008~2010. The species was selected as a sentinel species for the study, due to its wide distribution and wide trophic gradient. The analysis of trophic state index (TSI), based on total phosphorus (TP) and chlorophyll-a (Chl-a), indicated that reservoirs of $Y_yR$ and $B_aR$ were classified as to be in an oligotrophic state (30~40), the $J_yR$ and $G_pR$ as mesotrophic (40~50), and the $Y_dR$ and $M_sR$ as eutrophic state (50~70). Total 47 species and 26,226 individuals were sampled from 6 reservoirs and sensitive species dominated in the oligotrophic reservoirs ($Y_yR$ and $B_aR$). In the mean time, the tolerant speciesdominated the community in the mesotrophic ($J_yR$ and $G_pR$) and eutrophic ($Y_dR$ and $M_sR$) reservoirs. Regression analysis of body weight, against the total length, indicated that the regression coefficient (b value) was lower in the oligotrophic reservoir (2.77~2.79) than the mesotrophic (3.07~3.17) and eutrophic reservoirs (3.15~ 3.21). This result suggests that the population growth rate Zacco platypus reflected the trophic gradients of the reservoirs. The analysis of condition factor (K) against the total length showed positive slopes (b>3.0) in mesotrophic and eutrophic reservoirs, and a negative slope (b<3.0) in oligotrophic reservoir. The variation of the regression slope of "b" in Z. platypus was accounted for 79.7% [$b=0.012{\times}TSI(TP)+2.395$, p=0.017] by the variation of TSI (TP) and 82.2% [$b=0.013{\times}TSI(Chl-a)+2.36$, p=0.013] by the variation of TSI (Chl-a). The proportion of DELT abnormality increased as the trophic state increases in the reservoirs. The overall data suggest that the growth of the fish populations, based on the length-weight relations and condition factor, reflected the trophic state of nutrient and phytoplankton biomass of the reservoir waters. Thus, in spite of the tolerant characteristics of Z. platypus, hypertrophic states might negatively affect the health of the population.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.17 no.1
• /
• pp.123-134
• /
• 2014

Identification of methods to optimize the growth of a plant community, including the capacity of the soil to further sequester carbon, is important in urban design and planning. In this study, to construct and manage an urban park to mitigate carbon emissions, soil organic carbon of varying biomass, different park construction times, and a range of vegetation types were analyzed by measuring aboveground and belowground carbon in Seoseoul Lake Park and Yangjae Citizen's Forest. The urban parks were constructed during different periods; Seoseoul Lake Park was constructed in 2009, whereas Yangjae Citizen's Forest was constructed in 1986. To identify the differences in soil organic carbon in various plant communities and soil types, above and belowground carbon were measured based on biomass, as well as the physical and chemical features of the soil. Allometric equations were used to measure biomass. Soil total organic carbon (TOC) and chemical properties such as pH, cation exchange capacity (CEC), total nitrogen (TN), and soil microbes were analyzed. The analysis results show that the biomass of the Yangjae Citizen's Forest was higher than that of the Seoseoul Lake Park, indicating that older park has higher biomass. On the other hand, TOC was lower in the Yangjae Citizen's Forest than in the Seoseoul Lake Park; air pollution and acid rain probably changed the acidity of the soil in the Yangjae Citizen's Forest. Furthermore, TOC was higher in mono-layered plantation area compared to that in multi-layered plantation area. Improving the soil texture would, in the long term, result in better vegetation growth. To improve the soil texture of an urban park, park management, including pH control by using lime fertilization, soil compaction control, and leaving litter for soil nutrition is necessary.

• Korean Journal of Ecology and Environment
• /
• v.34 no.1 s.93
• /
• pp.45-53
• /
• 2001

Transport of cyanobacterial toxins (microcystin-LR, -RR, -YR) were assessed from a eutrophic lake, Lake Suwa, through the outflowing river, the Tenryu River, and its irrigation channel branch. Temporal variation of phytoplankton species composition in the river coincided with those of the lake; Microcystis ichthyoblabe dominated from June to July, and M. viridis dominated from August to September. When cyanobacterial bloom occurred, microcystins were continuously detected at the concentration of $0.3{\sim}3.2\;{\mu}g/l$ even at 32 km downstream. The change of the content of three microcystin variants were related both with the total cell density of Microcystis and with the change of Microcystis species composition. When Microcystis ichthyoblabe dominated during July, only microcystin-RR (MC-RR) and -LR (MC-LR) were detected, while when Microcystis viridis dominated between August and October, microcystin-RR,-YR (MC -YR) and -LR were detected. Along 29 km flowing distance (flow time 11 hours) between site 2 and site 5 in the Tenryu River, cyanobacterial density and microcystin concentration were reduced by 73% and 72%, respectively, which is mostly contributed by the dilution effect of tributary waters (61% and 57%, respectively) . In the artificial irrigation channel microcystins and cyanobacterial cells were decreased less than in the natural river. The results indicate that cyanobacterial toxins can be transported far downstream without much removal and give hazards to water usage in downstream of eutrophic lakes with cyanobacterial blooms.

• Proceedings of the Korean Quaternary Association Conference
• /
• 2004.06a
• /
• pp.49-50
• /
• 2004

푸른 진주라 불리는 훕스굴호는 러시아 국경에 인접한 몽고 북부의 청정호수로 해발 약 1,645m 지점에 위치한다. 훕스굴호의 길이는 약 136km이고, 폭은 20-40km이며, 최대수심은 약 262m 이다. 이 호수의 물은 세계에서 가장 깨끗한 담수 중 하나로 몽고 지표수원의 약 70%를 공급하고 있다. 훕스굴호는 바이칼 열곡대내에 형성된 일종의 구조호로 약 240만년 내지 400만년전에 형성된 것으로 추정되고 있다. 훕스굴호는 자연공원으로 지정되어 보호되고 있으며, 따라서 호수의 유역은 다행스럽게도 인간활동에 오염되거나 교란되지 않아 다양하고 흥미로운 육상/수성 생물상을 보유하고 있으며, 퇴적물 기록 역시 후기 신생대 동안의 중앙아시아의 지구환경 및 기후변화 연구에 매우 적합하다. 바이칼 시추사업 (Baikal Drilling Project)은 신생대 후기 동안의 중앙아시아의 지구조진화 및 전지구적 기후변화를 규명하기 위해 미국, 러시아, 일본, 독일 등이 참여한 다국가 공동사업이다. 바이칼 시추사업 연구팀은 지난 15년간 많은 노력과 예산을 투자하여 바이칼 호로부터 총 1,600m에 이르는 방대한 양의 퇴적물 코아를 성공적으로 회수하였고, 이 시료를 이용하여 후기 신생대 동안의 중부 유라시아 대륙의 고기후/고환경 진화과정을 성공적으로 규명하였다. 바이칼 시추사업이 성공적으로 진행됨에 따라, 이 사업에 참여했던 러시아와 일본의 과학자들은 바이칼호의 서쪽에 위치한 몽고 북부의 훕스굴에도 많은 관심을 가지게 되었으며, 동시에 바이칼 시추사업의 후속사업으로 훕스굴 시추사업을 새롭게 추진하게 되었다. 한편, 대륙내부에서의 제4기 지구환경 및 기후 변화 과정에 많은 관심을 가지고 연구해 오던 한국지질자원연구원도 2003년에 정식 회원으로 훕스굴 시추사업에 합류하였다. 훕스굴 시추사업 연구팀은 몽고의 지질광물자원연구소 (대표연구기관), 러시아의 지구화학연구소, 일본의 나고야대학교 그리고 한국의 지질자원연구원 등 4개국의 연구기관으로 구성되어 있다. 이들 4개 연구기관은 시추획득 및 기초연구 수행에 필요한 연구비를 현금 혹은 현물 (장비 포함)의 형태로 공동부담하고 있으며, 따라서 획득한 시추코아에 대해서도 각 연구기관이 전 구간에 대해 동일하게 25%의 소유권을 가지고 있다. 훕스굴 시추사업은 2008년까지 수행될 계획이며, 시추작업은 2005년까지 완료될 계획이다. 연구 진행과 관련하여, 공동연구의 명분을 높이고 분석의 효율성을 높이기 위해서 시료채취 및 기초자료 획득은 4개국의 연구원이 모여 공동으로 수행한 후의 결과물을 서로 공유하고, 자세한 전문분야 연구는 각 국의 대표기관이 독립적으로 수행하는 방식을 택하였다. 훕스굴에 대한 제1차 시추작업은 2004년 3월 말에 실시하였다. 시추작업 결과, 약 80m의 시추 코아가 성공적으로 회수되어 현재 러시아 이르쿠츠크 지구화학연구소에 보관중이다. 이 시추코아는 2004년 8월 중순경에 4개국 연구팀원들에 의해 공동으로 기재된 후에 분할될 계획이다. 분할된 시료는 국내로 운반되어 다양한 전문분야별 연구에 이용될 것이다. 한편, 제2차 시추작업은 2004년 12월에서 2005년 2월 사이에 실시될 계획이다. 수백만년에 이르는 장기간에 걸쳐 지구환경변화 기록이 보존되어 있는 훕스굴호에 대한 시추사업은 후기 신생대 동안 유라시아 대륙 중부에서 일어난 지구환경 및 기후변화를 이해함과 동시에 이러한 변화가 육상생태계 및 지표지질환경에 미친 영향을 이해하는데 크게 기여할 것이다.

• Journal of the Korean Geographical Society
• /
• v.40 no.5 s.110
• /
• pp.571-583
• /
• 2005

This paper presents a paleoenvironmental study on Hoya San Nicolas, a maar lake in Valle de Santiago in Central Mexican Bajio. Maar lake sediments have been widely used for high-resolution reconstruction of paleoenvironment. Many different paleoenvironmental proxy data such as stable isotopes, pollen, and sediment chemistry were produced in this study. These data help to reveal paleoenviromental changes throughout the whole period covered by sediment materials from this study site. The evidence indicates that during ca. 11,000 - ca. 8,900 cal yr B.P. there was dry climate; during ca. 8,900 - ca. 7,000 cal yr B.P. it was wetter; during ca. 7,000 - ca. 4,000 cal yr B.P. drier; during ca. 4,000 cal yr B.P - the present wetter. Prominent dominance of Pinus pollen during ca. 11,000 - ca. 8,900 cal yr B.P. and during ca. 7,000 - ca. 4,000 cal yr B.P. may reflect very low lake levels resulting in poor preservation of pollen. Pinus pollen, the most resistant pollen type, may have been able to survive severe deterioration due to arid climate, but other pollen types may not. Due to likely droughts in these periods, a sedimentation gaps are probably present in the core.

• Journal of Environmental Impact Assessment
• /
• v.23 no.6
• /
• pp.432-444
• /
• 2014

When the water quality modelling is done with a manual calibration, it is possible that the researcher's opinion may affect the objectivity of the research. Hence, the role of the automatic calibration is highly important. This research applies a technique to automatically calibrate the water quality parameters by implementing an optimization method. This involves estimating the optimum water quality parameters targeting influential parameters towards the lake's BOD, DO, Phosphorus, Nitrogen and Phytoplankton. To accurately calculate the water temperature and hydraulic characteristics of a deep, stratifying lake, EFDC, a 3-dimensional hydraulic model which can be linked to the WASP7 was applied. With EFDC, the segment of the lake is formed and utilized as an input data of the WASP7. For the calibration of the water quality parameters of the WASP7, an influence coefficient algorithm and a genetic algorithm was applied. Of the five water quality variables for calibration, the normalized residuals of the observed and calculated values of DO, TN, CBOD were relatively small and the three water quality variables were calibrated properly. Yet the accuracy of the calibration of TP and Chl-a was relatively low.

• Korean Journal of Microbiology
• /
• v.43 no.1
• /
• pp.40-46
• /
• 2007

For restoration of disturbed ecosystem in Lake Paro, artificial floating island (AFI) was installed. Even though the lake water was oligo-mesotrophic, the macrophytes, such as Iris ensata, Iris pseudoacorus, Phragmites communis were growing well in the rubberized coconut fiber media. For elucidating this process, total bacterial numbers, active bacterial numbers and exoenzymatic activities of ${\beta}-glucosidase$ and phosphatase of pore water of media and lake water were analyzed. The average of total bacterial numbers, active bacterial numbers and exoenzymatic activities of ${\beta}-glucosidase$ and phosphatase were $28.6{\times}10^{6}\;cells/ml,\;22.7{\times}10^{6}\;cells/ml,\;452.9nM/L/hr,\;and\;16381.9nM/L/hr$ which were 10, 15, 22 and 38 times higher than those of lake water, respectively. Moreover, the total phosphorus and total nitrogen concentration of media showed high values of 0.82 mg/L and 7.0 mg/L, respectively, while those of lake water 0.07 mg/L and 2.3 mg/L. This results suggest that the bacteria was playing an important role for restoration of disturbed ecosystem with newly created microbial ecosystem in media of artificial floating island.

• Analytical Science and Technology
• /
• v.24 no.5
• /
• pp.378-386
• /
• 2011

The goal of this study is to understand the influence of temperature on phosphorus release rate from soil into water. As the temperature increases, $PO_4$-P reaches equilibrium more quickly and the equilibrium concentration increases, and thus the $PO_4$-P concentration increases, and pH decreases. The $PO_4$-P concentration affects pH. $PO_4$-P released from turbidity is not adsorbed onto the turbidity. $PO_4$-P was independent on the turbidity and yet $PO_4$-P was steadily increasing. However, $PO_4$-P was dependent upon the turbidity concentration as the turbidity releases $PO_4$-P. The total phosphorous (T-P) and turbidity were directly linked because T-P changed with the turbidity. T-P includes the $PO_4$-P content of water and the phosphorus content of the turbidity. As the temperature decreases, density of water increases, and the precipitation of turbidity decreases, resulting in an increases in T-P concentration. As the temperature increases, the T-P concentration decreases, but the PO4-P release rate from turbidity increases. At the same time, even at different temperatures, the T-P concentrations of the samples were about the same. When the lake gets deepened, the water temperature decreases, hence, the phosphorus release rate from soil into water was decreased. This mechanism is of great interest because phosphorus is released from soil sediment into the lake water.