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  • 1
    Article
    Article
    Language: Korean
    In: 한국정보관리학회 학술대회 논문집, 2017, Vol.2017(8), pp.103-103
    Keywords: Ecological Data Lake River Aquatic
    Source: DBpia - 디비피아 (Nurimedia)
    Source: DBpia (Nurimedia)
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  • 2
    Language: English
    In: Journal of Hydrology, Feb 13, 2014, Vol.509, p.601(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2013.12.005 Byline: Svenja Bartsch, Sven Frei, Marianne Ruidisch, Christopher L. Shope, Stefan Peiffer, Bomchul Kim, Jan H. Fleckenstein Abstract: acents Temporal variability of river-aquifer exchange fluxes is controlled by the monsoon. acents Monsoonal extreme precipitation events are dominant drivers for flow reversals. acents Frequent flow reversals affect the local water quality. Article History: Received 26 August 2013; Revised 3 December 2013; Accepted 5 December 2013 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of Philippe Negrel, Associate Editor
    Keywords: Aquifers ; Rain ; Climate
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Environmental Pollution, 2010, Vol.158(2), pp.347-355
    Description: The effects of various factors including turbidity, pH, DOC, temperature, and solar radiation on the concentrations of total mercury (TM) and dissolved gaseous mercury (DGM) were investigated in an artificial reservoir in Korea. Episodic total mercury accumulation events occurred during the rainy season as turbidity increased, indicating that the TM concentration was not controlled by direct atmospheric deposition. The DGM concentration in surface water ranged from 3.6 to 160 pg/L, having a maximum in summer and minimum in winter. While in most previous studies DGM was controlled primarily by a photo-reduction process, DGM concentrations tracked the amount of solar radiation only in winter when the water temperature was fairly low in this study. During the other seasons microbial transformation seemed to play an important role in reducing Hg(II) to Hg(0). DGM increased as dissolved organic carbon (DOC) concentration increased ( -value 〈 0.01) while it increased with a decrease of pH ( -value 〈 0.01). Long-term in-situ monitoring of TM and DGM concentrations with various factors was executed in a large artificial reservoir in this study.
    Keywords: TM (Total Mercury) ; Dgm (Dissolved Gaseous Mercury) ; Reduction ; Doc (Dissolved Organic Carbon) ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 4
    Language: English
    In: Journal of Hydrology, 13 February 2014, Vol.509, pp.601-614
    Description: An important prerequisite to better understand the transport of nutrients and contaminants across the river-aquifer interface and possible implications for biogeochemical transformations is to accurately characterize and asses the exchange fluxes. In this study we investigate how monsoonal precipitation events and the resulting variability in river discharge affect the dynamics of river-aquifer exchange and the corresponding flux rates. We evaluate potential impacts of the investigated exchange fluxes on local water quality. Hydraulic gradients along a piezometer transect were monitored at a river reach in a small catchment in South Korea, where the hydrologic dynamics are driven by the East-Asian Monsoon. We used heat as a tracer to constrain river-aquifer exchange fluxes in a two-dimensional flow and heat transport model implemented in the numerical code HydroGeoSphere, which was calibrated to the measured temperature and total head data. To elucidate potential effects of river-aquifer exchange dynamics on biogeochemical transformations at the river-aquifer interface, river water and groundwater samples were collected and analyzed for dissolved organic carbon (DOC), nitrate (NO ) and dissolved oxygen saturation (DO ). Our results illustrate highly variable hydrologic conditions during the monsoon season characterized by temporal and spatial variability in river-aquifer exchange fluxes with frequent flow reversals (changes between gaining and losing conditions). Intense monsoonal precipitation events and the associated rapid changes in river stage are the dominant driver for the observed riverbed flow reversals. The chemical data suggest that the flow reversals, when river water high in DOC is pushed into the nitrate-rich groundwater below the stream and subsequently returns to the stream may facilitate and enhance the natural attenuation of nitrate in the shallow groundwater.
    Keywords: River-Aquifer Exchange Fluxes ; Heat As a Natural Tracer ; Monsoonal-Type Climate ; Hydraulic Gradient Reversals ; Hydrogeosphere ; Natural Attenuation of Nitrate ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: Environmental pollution, 2010, Vol.158, pp.347-355
    Description: The effects of various factors including turbidity, pH, DOC, temperature, and solar radiation on the concentrations of total mercury (TM) and dissolved gaseous mercury (DGM) were investigated in an artificial reservoir in Korea. Episodic total mercury accumulation events occurred during the rainy season as turbidity increased, indicating that the TM concentration was not controlled by direct atmospheric deposition. The DGM concentration in surface water ranged from 3.6 to 160 pg/L, having a maximum in summer and minimum in winter. While in most previous studies DGM was controlled primarily by a photo-reduction process, DGM concentrations tracked the amount of solar radiation only in winter when the water temperature was fairly low in this study. During the other seasons microbial transformation seemed to play an important role in reducing Hg(II) to Hg(0). DGM increased as dissolved organic carbon (DOC) concentration increased (p-value 〈 0.01) while it increased with a decrease of pH (p-value 〈 0.01). Long-term in-situ monitoring of TM and DGM concentrations with various factors was executed in a large artificial reservoir in this study. ; Includes references ; p. 347-355.
    Keywords: Agricultural Watersheds ; Reservoirs ; Dissolved Organic Carbon ; Lakes ; Atmospheric Deposition ; Forested Watersheds ; Temperature ; Meta-Analysis ; Solar Radiation ; Turbidity ; Water Pollution ; Ph ; Mercury ; Literature Reviews
    ISSN: 0269-7491
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 6
    In: Ecological Applications, January 2015, Vol.25(1), pp.186-199
    Description: A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the “high hazardous” category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures.
    Keywords: Bayesian Network ; Climate Change ; Cyanobacterial Blooms ; Multiple Systems ; Nutrients ; Risk Assessment ; Uncertainty
    ISSN: 1051-0761
    E-ISSN: 1939-5582
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  • 7
    Language: English
    In: Journal of Hydrology, 28 June 2013, Vol.494, pp.72-82
    Description: River discharge is a commonly measured hydrologic variable; however, estimate uncertainty is often higher than acceptable limits. To quantify method limitations and spatiotemporal variability, a multi-year hydrologic flow partitioning investigation was completed under monsoonal conditions in the ungauged complex terrain of the Haean Catchment, South Korea. Our results indicate that sediment transport from a single annual monsoonal event can significantly modify the channel cross-sectional area resulting in inaccurate stage-discharge rating curves. We compare six discharge measurement methods at 13 locations that vary in slope from 1% to 80%, with discharge ranging up to four orders in magnitude, which enabled us to weight the accuracy of each method over a specific range in discharge. The most accurate discharge estimation methods are the weir, the acoustic Doppler current profiler, and the in-stream velocity area method; however, under certain conditions each of these methods is less desirable than other methods. The uncertainty in the three methods is on average 0.4%, 4.7%, and 6.1% of the total discharge, respectively. The accuracy of the discharge estimates has a direct influence on the characterization of basin-wide hydrologic partitioning, which can lead to significant variability in sediment erosion rates and nutrient fate and transport.
    Keywords: Terreco ; Korea ; Discharge ; Baseflow ; Topography ; River ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 8
    Language: English
    In: Journal of Hydrology, 12 December 2013, Vol.507, pp.149-162
    Description: The linkage between hydrologic dynamics and the delivery of nitrate and DOC (dissolved organic carbon) to streams was studied in the Haean catchment, a mixed land-use mountainous catchment in South Korea. Three monsoonal precipitation events were analyzed, which varied in total rainfall amount (39–70 mm) and intensities (mean: 1.6–5.6 mm h ), by high-resolution (2–4 h interval) stream water-quality sampling along the topographic elevation gradient of the catchment, from an upland deciduous forest stream, over areas intensively used for agriculture (dryland farming and rice paddies) down to the catchment outlet. The dynamics of river-aquifer exchange were investigated at two piezometer transects at mid and lower elevations. DOC and nitrate sources and their transport pathways to the receiving surface waters differed between the forested and the agricultural stream site. In the forest stream, elevated DOC concentrations (max: 3.5 mgC l ) during precipitation events were due to hydrologic flushing of soluble organic matter in upper soil horizons, with a strong dependency on pre-storm wetness conditions. Nitrate contributions to the forested stream occurred along shallow subsurface transport pathways. At the agricultural sites stream DOC concentrations were considerably higher (max: 23.5 mgC l ) supplied from adjacent rice paddies. The highest in-stream nitrate concentrations (max: 4.1 mgN l ) occurred at river reaches located in the lower agricultural part of the catchment, affected by groundwater inputs. Groundwater nitrate concentrations were high (max: 7.4 mgN l ) owing to chemical fertilizer leaching from dryland fields forced by monsoonal rainfalls. Overall, this study demonstrates that the hydrologic dynamics resulting from the monsoonal climate drive the in-stream DOC dynamics in the forested 1st-order catchment whereas sources and mobilization of DOC in downstream agricultural areas are mainly controlled by the prevailing land-use type and irrigation management. Nitrate dynamics in higher order agricultural streams and their connected aquifers reflect combined effects of land-use type and monsoonal hydrology.
    Keywords: Nitrate ; Dissolved Organic Carbon ; Monsoonal-Type Climate ; Land-Use Type ; River-Aquifer Exchange Dynamics ; Topography ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
    Source: ScienceDirect Journals (Elsevier)
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  • 9
    Language: English
    In: Journal of hydrology, 2012, Vol.440, pp.90-101
    Description: Although soil erosion and leaching can transfer a substantial portion of the annual terrestrial carbon (C) increment to aquatic systems, little is known about rapid changes in the amount and characteristics of soil organic C exported from mountainous watersheds during storm events. To trace short-term changes in sources and characteristics of soil organic C exported during storm events, we investigated storm-induced changes in concentrations of particulate and dissolved organic C (POC and DOC) and the stable isotope composition of suspended sediment (SS) in a mountainous, mixed land-use watershed in northern South Korea. Biweekly stream sampling in a headwater forest stream and a watershed outlet receiving agricultural runoff showed that concentrations of SS and POC were higher in the watershed outlet. In both the forest stream and outlet, POC concentrations were lower than DOC concentrations during baseflow, but increased rapidly with rising discharge during intense storms, resulting in higher peak POC concentrations than peak DOC concentrations. When δ¹³C and δ¹⁵N were compared between SS and potential source soils during three storm events, SS δ¹³C and δ¹⁵N in the forest stream were similar to forest floor δ¹³C and δ¹⁵N. SS δ¹³C and δ¹⁵N in the watershed outlet reflected the contribution from forest and cropland mineral soils during peak flow, with sand-size SS displaying increasing δ¹³C and δ¹⁵N with rising rainfall intensity. The results suggest that storm pulses of POC can be a transient, but dominant pathway of hydrologic C export overwhelming DOC export and that POC sources and characteristics can rapidly change corresponding to varying rainfall intensity. ; p. 90-101.
    Keywords: Forests ; Soil Organic Carbon ; Exports ; Carbon ; Mineral Soils ; Forested Watersheds ; Streams ; Storms ; Soil Erosion ; Stable Isotopes ; Forest Litter ; Rain Intensity
    ISSN: 0022-1694
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 10
    Language: English
    In: Journal of Hydrology, 29 May 2012, Vol.440-441, pp.90-101
    Description: ► Storm pulses of C export represent soil C losses from mountainous watersheds. ► Storm pulses of POC can be a dominant pathway of C export overwhelming DOC export. ► POC sources can rapidly change with varying rainfall intensity during storms. ► Coupled soil and sediment stable isotope measurements are useful in tracing C export. Although soil erosion and leaching can transfer a substantial portion of the annual terrestrial carbon (C) increment to aquatic systems, little is known about rapid changes in the amount and characteristics of soil organic C exported from mountainous watersheds during storm events. To trace short-term changes in sources and characteristics of soil organic C exported during storm events, we investigated storm-induced changes in concentrations of particulate and dissolved organic C (POC and DOC) and the stable isotope composition of suspended sediment (SS) in a mountainous, mixed land-use watershed in northern South Korea. Biweekly stream sampling in a headwater forest stream and a watershed outlet receiving agricultural runoff showed that concentrations of SS and POC were higher in the watershed outlet. In both the forest stream and outlet, POC concentrations were lower than DOC concentrations during baseflow, but increased rapidly with rising discharge during intense storms, resulting in higher peak POC concentrations than peak DOC concentrations. When C and N were compared between SS and potential source soils during three storm events, SS C and N in the forest stream were similar to forest floor C and N. SS C and N in the watershed outlet reflected the contribution from forest and cropland mineral soils during peak flow, with sand-size SS displaying increasing C and N with rising rainfall intensity. The results suggest that storm pulses of POC can be a transient, but dominant pathway of hydrologic C export overwhelming DOC export and that POC sources and characteristics can rapidly change corresponding to varying rainfall intensity.
    Keywords: Dissolved Organic Carbon ; Extreme Events ; Hydrologic Carbon Export ; Stable Isotopes ; Particulate Organic Carbon ; Soil Carbon ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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