• Fisheries and Aquatic Sciences
• /
• 제8권3호
• /
• pp.167-176
• /
• 2005

Atmospheric deposition and riverine waters were sampled throughout a year, to estimate the loading fluxes of polycyclic aromatic hydrocarbons (PAHs) into the Masan Bay and its vicinity, Korea. Atmospheric deposition fluxes of total PAHs in the surveyed area varied from 62.2 to 464 ${\mu}g/m^2/year$. Concentration of total PAHs in water samples from six rivers ranged from 34.6 to 239 ng/L. Contribution of the carcinogenic PAHs to the total PAHs occupied $38\%$ and $50\%$ for atmospheric deposition and river waters, respectively. Atmospheric deposition fluxes and water concentrations of PAHs were slightly low or moderate to those in locations from some countries. Correspondence analysis was used to investigate the loading characteristics of PAHs according to transport routes. Atmospheric deposition samples were corresponded to higher molecular aromatics of PAHs, while riverine water samples were associated with lower molecular weight of PAHs. The results indicate that the higher-molecular-weight PAHs can be primarily transported by atmosphere deposition and the lower-molecular-weight PAHs can be mainly contaminated by riverine discharge into the Masan Bay and its vicinity. Loadings fluxes of PAHs into the Masan Bay and its vicinity were 39.2 g/day via atmosphere and 10.3 g/day via rivers, showing that atmospheric input was about 4 times higher than riverine one. Therefore, in order to minimize the contamination burden of PAHs from terrestrial sources to the Masan Bay and its vicinity, the control and management of PAHs deriving from atmosphere will be necessary.

• Journal of the korean society of oceanography
• /
• 제36권3호
• /
• pp.59-71
• /
• 2001

In order to investigate the temporal variability of dissolved and particulate trace metals in the Han River, water samples were collected intermittently at two sites for 3 years (August 91 to December 94). Surface seawaters covering the range of salinity were also collected at the estuarine region to evaluate the role of estuary for the riverine fluxes of trace metals within the estuary during October 95 and 96. During the study period, dissolved metal concentrations in riverwaters varied by a factor of 5-10 for Fe, Ni, Co and Cu and 50-100 for Mn, Cd and Pb depending upon the water level; high concentration during the low water and low concentration in high water period except for Fe. The concentration of dissolved Fe increased with increasing water discharge. These concentration-discharge relationships of the studied trace metals are explained by the successive dilution of waters from two different origins, which can be presumably identified as anthropogenic discharges and watershed flushing. Although estuarine waters at early mixing region were not collected due to the difficulty of sampling, mixing behaviors of metals were inferred from the concentration-salinity relationships through the laboratory mixing experiment and field sampling, and distribution coefficients between dissolved and labile particulate phases. It is suggested that the Han River estuary plays a role of accumulating Fe, Mn, Co and Pb from riverine sources due to high turbidity caused by strong tidal current, whereas this system serves as a source of dissolved Cd due to release caused by extended residence time of riverine particles.

• Fisheries and Aquatic Sciences
• /
• 제13권3호
• /
• pp.236-243
• /
• 2010

Fecal sterols, nonylphenolic compounds (NPs), and polycyclic aromatic hydrocarbons (PAHs) were determined in surface water from Masan Bay and its adjacent rivers in February 2005. Concentrations of coporstanol (Cop), an indicator of fecal pollution, in surface water ranged from <10 to 13,853 ng/L, and concentrations of nonylphenol, the most toxic of the NPs, ranged from 10.2 to 481 ng/L, and concentrations of PAHs ranged from 8.61 to 223 ng/L. The concentrations of the compounds measured in this study were lower than or comparable to those at other locations in Korea and other countries. The contamination of Cop and PAHs in surface water was associated with the discharge from rivers passing through cities and/or industrial complexes. The NP contamination was associated with wastewater treatment plant (WWTP) effluents through outfalls as well as riverine discharge. Compared to ecotoxicological values, the concentrations of NPs from rivers, the mouths of rivers, and WWTP outfall areas exceeded guidelines, suggesting that hot spot areas may pose a potential risk to sensitive species.

• Journal of the korean society of oceanography
• /
• 제32권3호
• /
• pp.156-161
• /
• 1997

The biogeochemical cycle of silver has rarely been reviewed, even though the silver ion (Ag$^{\times}$) is extremly toxic to some organisms. Its concentration is still rising sharply because of increased anthropogenic activity, specifically the discharge from the film industry (mainly, silver thiosulfate: Ag (S$_2$O$_3$)${^3-}_2$). Recently, a number of researchers have quantified the major fluxes and reservoirs of silver in the open ocean, bays, and estuaries. A review of the available information for Ag cycling in the open ocean shows that the riverine input (from human activity and weathering processes: 7${\times}$10$^6$ kg/yr and 5${\times}$10$^6$ kg/yr, respectively) is the dominant source of Ag to estuarine and coastal regions. Most of the silver (90% of riverine input silver) is removed in coastal sediments by the physical-chemical character of silver due to its high partitioning with particulate matter. On the other hand, in the open ocean the atmospheric input (wet and dry deposition: 1.48${\times}$10$^6$ kg/yr and 1.94${\times}$ 10$^5$ kg/yr, respectively) becomes more important as a source of silver than riverine input. The residence time of silver calculated from available data is 1250 yrs in the deep ocean below 500 m, but only 3 yrs in the surface ocean.

• 생태와환경
• /
• 제49권4호
• /
• pp.245-257
• /
• 2016

하천이 차지하는 면적은 전체 육지 면적의 약 0.5%에 불과하지만, 하천수의 조성은 유역 환경의 생지화학적 변화를 집약적으로 반영하는 지표가 될 수 있다. 하천 탄소의 농도는 수질과 직접적인 관련이 있고, 또한, 하천을 통해 바다로 유출되는 탄소량을 순 생태계 생산량 (NEP)에서 빼주지 않으면 생태계 내 저장될 수 있는 탄소량이 과다 산정될 수 있기 때문에 하천의 탄소 유출량을 정확히 추정하려는 연구가 꾸준히 이뤄지고 있다. 전 세계적으로 하천을 통해 바다로 유출되는 총 탄소량은 약 $0.8{\sim}1.5Pg\;yr^{-1}$, 수체로부터 대기로 빠져나가는 양이 약 $0.62{\sim}2.1Pg\;yr^{-1}$로 추정된다. 우리나라의 하천 탄소에 대한 연구는 주로 수질과 관련된 유기탄소에 집중된 편이며, 농도, ${\delta}^{13}C$, 형광스펙트럼 분석 결과 강수량과 강수 세기 등 시간에 따른 차이와 토지 이용 등 공간적인 차이에 따라 다양한 성상의 탄소가 하천으로 유입되는 것으로 여겨진다. 인간의 토지이용과 기후변화의 영향으로 인한 탄소순환 동태의 변화는 하천의 총 탄소 함량뿐만 아니라 DIC, DOC, POC의 비율에도 변화를 불러오고, 이들과 함께 수체 내에서 이동하는 다양한 유기/무기 오염물질의 양과 분해도에도 영향을 줄 수 있다. 따라서, 기존의 분석 방법에 더해 탄소연대 측정과 초고분해능 질량 분석 등의 방법을 활용하여 하천 탄소의 기원, 변화, 분해 과정을 면밀히 유추하는 연구가 필요하다. 장기적으로, 넓은 유역을 대상으로 얻어진 하천 탄소의 성상별 농도와 일유량 자료는 유역 생태계의 변화를 추적하고, 자연적인 또는 인간에 의한 교란 때문에 일어나는 환경 변화를 예측하는 데 유용하게 쓰일 수 있다. 현재 정부가 운영 중인 수질측정망을 대상으로, 알칼리도를 포함한, 하천 탄소의 성상별 농도가 분석 항목에 추가되고, 일유량 자료와 개별 연구진이 얻은 연구결과를 포함하는 데이터베이스가 구축되어, 이러한 자료가 보다 효율적으로 활용될 수 있기를 바란다.

• 환경영향평가
• /
• 제20권3호
• /
• pp.325-335
• /
• 2011

Estuary is a transitional zone between river and ocean environment that receives the maritime and riverine influence simultaneously. Estuaries are the most productive habitats because their incoming water provides large quantities of nutrients. The Seomjin River estuary, located in the middle south of Korea, has no barrage and shows natural characteristic of estuary. However, due to dredging and reclamation the environment of the estuary has been changed significantly in the river mouth. In addition, increased freshwater intake in midstream of the Seomjin River results in salinity intrusion. In this paper salinity variation in downstream estuary of the Seomjin River has been simulated and tested using EFDC model. The results of simulation were compared with measured data collected at three points, Culture & Art Center, Sumjin Iron Bridge, and Mokdori, located at 9Km, 14Km, and 15.5Km respectively from downstream estuary. Based on the simulated results, the contribution of the flushing discharge has been evaluated in preventing the salinity intrusion by increasing the discharge flowrates released from the Juam dam.

• 생태와환경
• /
• 제43권4호
• /
• pp.471-476
• /
• 2010

Monthly up-river discharge in the riverine zone analysis resulted in large interannual variations and differences in calcium ($Ca^{2+}$), bicarbonate ($HCO_3^-$), and cations in the lacustrine zone (Lz) of Daecheong Reservoir during the wet year (Wy, 1993) vs. dry year (Dy, 1994). Total up-river discharge in the Wy was four times that of the Dy, and the up-river discharge in July~August of the Wy was eight times greater than that of same period of Dy. Annual water retention time in the Lz showed large difference between the two years. Water residence time (WRT) was minimum when the up-river discharge peaked, whereas the WRT was maximum when the up-river discharge was at minimal condition. This peak discharge from the up-river on early July reduced residence time in the Lz on mid-July~late July. Monthly pattern, based on data of May~November, was similar between the two years, but, but mean retention time in the Wy was 50 days shorter than in the Dy. Such hydrology, up-river discharge, and WRT reduced $Ca^{2+}$, $HCO_3^-$, and cations in the Lz. At low up-river discharge in Wy during April~May, the cation content of Ca+Mg+Na+K averaged 1.17meq $L^{-1}$ (range=1.09-1.26meq $L^{-1}$), but as the up-river discharge increased suddenly, the values decreased. Seasonal fluctuations of $Ca^{2+}$ showed exactly same pattern with bicarbonate ion of $HCO_3^-$. The minimum $Ca^{2+}$ (0.03meq $L^{-1}$) was occurred in the early August of wet year and coincided with the minimum $HCO_3^-$. These results suggest that the magnitude of variation in $Ca^{2+}$, bicarbonate, and cations in the lacustrine zone is directly determined by the peak magnitude of up-river discharge. The magnitude of up-river discharge determined water retention time and the magnitude of ionic dilution in the lacustrine zone, resulting in functional changes of the ecosystem.

• 생태와환경
• /
• 제46권1호
• /
• pp.10-17
• /
• 2013

History of Instream Flow Incremental Methodology (IFIM) Following the large reservoir and water development era of the mid-twentieth century in North America, resource agencies became concerned over the loss of many miles of riverine fish and wildlife resources in the arid western United States. Consequently, several western states began issuing rules for protecting existing stream resources from future depletions caused by accelerated water development. Many assessment methods appeared during the 1960's and early 1970's. These techniques were based on hydrologic analysis of the water supply and hydraulic considerations of critical stream channel segments, coupled with empirical observations of habitat quality and an understanding of riverine fish ecology. Following enactment of the National Environmental Policy Act (NEPA) of 1970, attention was shifted from minimum flows to the evaluation of alternative designs and operations of federally funded water projects. Methods capable of quantifying the effect of incremental changes in stream flow to evaluate a series of possible alternative development schemes were needed. This need led to the development of habitat versus discharge functions developed from life stage-specific relations for selected species, that is, fish passage, spawning, and rearing habitat versus flow for trout or salmon. During the late 1970's and early 1980's, an era of small hydropower development began. Hundreds of proposed hydropower sites in the Pacific Northwest and New England regions of the United States came under intensive examination by state and federal fishery management interests. During this transition period from evaluating large federal reservoirs to evaluating license applications for small hydropower, the Instream Flow Incremental Methodology (IFIM) was developed under the guidance of the U.S. Fish and Wildlife Service (USFWS).

• 한국수자원학회논문집
• /
• 제53권1호
• /
• pp.15-27
• /
• 2020

하천 유량관측은 수자원의 관리를 위해 활용되는 기초적이고 대표적인 자료로 하천에서 정확한 유량을 관측하는 것은 중요하다. 따라서 최근에는 다양한 첨단 장비들이 개발되어 전통적인 하천의 유량관측을 대체하거나 보완하고 있다. 여러 최신 장비들 중 전자파표면유속계는 홍수기와 같이 하천에 접근하여 직접유량계측이 위험하고 정확도 확보가 어려울 경우전자파를 이용하여 비접촉식으로 유량을 계측하는 장비로 홍수기 및 평갈수기에도 하천 유량계측에 활용되기 시작하였다. 전자파표면유속계는 사용법이 간단하고 간접적으로 유속을 측정하기 때문에 기존의 직접측정 방법에 비해 안전한 장점이 있어 현재 국내에서는 홍수기 또는 접근이 어려운 하천의 유속 측정을 위해 사용되고 있다. 국내에서는 1993년 유량측정 장치 개발을 위해 전자파표면유속계(MWSCM; Microwave Water Surface Current Meter)를 개발을 연구를 수행하였고, 최근에는 국내에서 개발된 전자파표면유속계을 활용하여 유량측정을 위해 사용되고 있다. 하지만 국내에서 개발된 전자파표면유속계가 실제 하천에서 유속측정의 정확도에 대한 연구는 부족한 실정이다. 전자파표면유속계는 기기로부터 전자파를 이용해 유속을 측정하기 때문에 수직각과 편각과 같은 각도 변화에 따라 측정정확도가 바뀔 수 있고, 전자파표면유속계 본체에서 발사되는 전자파의 측정영역에 따라 유속측정에 오차가 발생할 수 있다. 본 연구에서는 국내에서 개발 전자파표면유속계의 측정정확도를 분석하기 위해서 실제하천과 유사한 실규모 하천수로에서 수직각과 편각을 변화시키며 측정을 수행하여 수직각과 편각에 변화에 따른 유속측정 정확도를 분석하였다. 그리고 전자파표면유속계의 측정영역의 고려를 통해서 측정영역에 따른 유속측정결과를 분석하였다. 유속측정 결과를 통해서 수직각 15° 이하에서는 유속측정의 오차가 커지게 되는 것으로 나타났고, 편각이 커질수록 유속측정의 결과의 변동계수가 커지는 것으로 나타났다. 그리고 편각에 따른 오차의 영향은 전자파표면유속계의 측정영역에 따라 결과가 달라지는 것으로 나타났다.

• 한국환경과학회지
• /
• 제20권1호
• /
• pp.107-118
• /
• 2011

While the assessment of mean flow field is very important to characterize the hydrodynamic aspect of the flow regime in river, the conventional methodologies have required very time-consuming efforts and cost to obtain the mean flow field. The paper provides an efficient technique to quickly assess mean flow field by developing and applying spatial averaging method utilizing repeatedly surveyed acoustic Doppler current profiler(ADCP)'s cross-sectional measurements. ADCP has been widely used in measuring the detailed velocity and discharge in the last two decades. In order to validate the proposed spatial averaging method, the averaged velocity filed using the spatial averaging was compared with the bench-mark data computed by the time-averaging of the consistent fix-point ADCP measurement, which has been known as a valid but a bit inefficient way to obtain mean velocity field. The comparison showed a good agreement between two methods, which indicates that the spatial averaging method is able to be used as a surrogate way to assess the mean flow field. Bed shear stress distribution, which is a derived hydrodynamic quantity from the mean velocity field, was additionally computed by using both spatial and time-averaging methods, and they were compared each other so as to validate the spatial averaging method. This comparison also gave a good agreement. Therefore, such comparisons proved the validity of the spatial averaging to quickly assess mean flow field. The mean velocity field and its derived riverine quantities can be actively used for characterizing the flow dynamics as well as potentially applicable for validating numerical simulations.