• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.8-14
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• 2007

Water quality in Lake Rotorua, New Zealand, deteriorated since the 1960s because of excessive phytoplankton growths due principally to increasing nitrogen and phosphorus in the lake waters. Nutrient concentrations in eight of the nine major streams feeding Lake Rotorua have increased since 1965. The groundwater system has a key role in the hydrology of the Lake Rotorua catchment and the groundwater system is probably the control on the time delay between intensification of agricultural land use and response of surface water quality. All major, and many minor streams, in the catchment are fed by springs. Two lithological units are most important to groundwater flow in the Lake Rotorua catchment: Mamaku Ignimbrite, erupted in about 200,000 years ago and Huka Formation sediments which filled the caldera left by the Mamaku Ignimbrite eruption. Rainfall recharge to groundwater in the groundwater catchment of Lake Rotorua is estimated as approximately 17300 L/s. A calibrated steady-state groundwater flow model estimates that approximately 11100 L/s of this flow discharges into streams and then into the lake and the balance travels directly to Lake Rotorua as groundwater discharge through the lake bed. Land use has impacted on groundwater quality. Median Total Nitrogen (TN) values for shallow groundwater sites are highest for the dairy land use (5.965 mg/L). Median TN values are also relatively high for shallow sites with urban-road and cropping land uses (4.710 and 3.620 mg/L, respectively). Median TN values for all other uses are in the 1.4 to 1.5 mg/L range. Policy development for Lake Rotorua includes defining regional policies on water and land management and setting an action plan for Lake Rotorua restoration. Aims in the action plan include: definition of the current nutrient budget for Lake Rotorua, identification of nutrient reduction targets and identification of actions to achieve targets. Current actions to restore Lake Rotorua water quality include: treatment of Tikitere geothermal nitrogen inputs to Lake Rotorua, upgrade of Rotorua City sewage plant, new sewage reticulation and alum dosing in selected streams to remove phosphorus.

• Ocean and Polar Research
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• v.26 no.3
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• pp.507-514
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• 2004

A sediment core drilled from Lake langer on King George Island was analyzed for a variety of textural md geochemical properties along with $^{14}C$ age dates. These data were combined with published records of other cores to provide a detailed history of Holocene variation of total organic carbon (TOC) contents with respect to terrestrial paleoclimate change. The lithologic contrast of the lower diamicton and upper fine-grained sediments shows the glacier activity and subsequent lake formation. Low TOC contents fluctuated during the diamicton deposition whereas the increase of TOC began with the lake formation during the postglacial period that started about 5,000 yr B.p More notable are the distinct TOC peaks that may imply enhanced primary productivity during the warm period. The uniform and low TOC contents may reflect the limited productivity during the evolution of the lake. However, the recent TOC readvance clearly indicates gradual warming on King George Island. However, the paleoclimatic signature in the terrestrial lake environment during the Holocene seems to be subtle and less distinct, compared to the marine environment.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.81-86
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• 2007

This paper describes a study on the role of limestone which might affect the dissolution of phosphates when phosphate containing sediments are put under anaerobic conditions. A small quantity of calcium hydroxy-apatite, alone or mixed with limestone powder, was put in contact with aqueous solution of acetic acid or carbonic acid, and variations of phosphate concentration were determined time dependantly. The results showed that the concentration was remarkably low in the presence of limestone, signifying that the coexistence of limestone suppresses the dissolution of phosphate by organic acid and/or carbonic acid. Separate experiments conducted by developing an anaerobic condition, after mixing lake sediments with dried leaves and limestone, showed that the existence of limestone suppressed the dissolution of phosphate. These results show that the application of limestone might be a useful measure to prevent deterioration of water quality originated from eutrophication by inhibiting the internal loading of P in eutrophic water-bodies.

• Journal of Environmental Health Sciences
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• v.38 no.5
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• pp.424-430
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• 2012

Objective: The purpose of this study was to present the standard deviation of the elemental normalization of concentration of selected heavy metals in the surface sediment of Lake Paldang. Methods: Grain size dependency of selected heavy metal concentrations in the surface sediments of Lake Paldang was analyzed by the extrapolation method. The heavy metal concentrations were the sum of all fractions. Results: Cd and Cu showed an increase of the coefficient of determination($r^2$) in the fractional content of particle size, from <256 ${\mu}m$ to <20 ${\mu}m$, and a decrease from <20 ${\mu}m$ to <1 ${\mu}m$. The normalized concentration of Cd and Cu by extrapolation at 50% <20 ${\mu}m$ were 0.8 mg/kg, 37.0 mg/kg, 57.6 mg/kg and 201.7 mg/kg respectively. Conclusions: The normalized concentrations in the sediment of Lake Paldang are 1.5-2.0 times higher than mean average concentration. We concluded that in interpretation of heavy metal concentration in the sediment of Lake Paldang, normalization of grain size dependency should be considered.

• Journal of Wetlands Research
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• v.8 no.4
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• pp.49-58
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• 2006

The extent and degree of contaminated sediments on lake Paldang were analyzed at 40 sites for organic matters, nutrients and heavy metals. COD, T-N and T-P were fairly correlated with the grain size of sediments, and the sites which were most distributed with sand were less contaminated with the sites covered with silt and clay. Phosphorus species were in the range of 7-58 for adsorbed-P, $13{\sim}411{\mu}g/g$ for NAI-P, $52{\sim}482{\mu}g/g$ for Apatite-P and $75{\sim}894{\mu}g/g$ for residual-P, respectively. Although heavy metals of sediments were detected at the range of $0.2-4.2{\mu}g/g$(Cr), $1.6{\sim}20.7{\mu}g/g$(Cu), 1.4~78.0ng/g(Hg), $2.1{\sim}18.9{\mu}g/g$(Pb), $1.8{\sim}99.5{\mu}g/g$(Zn), further survey over the long period were required for more monitoring data. The release rate of nutrients were found no relationship in this study.

• Journal of The Geomorphological Association of Korea
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• v.25 no.3
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• pp.43-55
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• 2018

This study aimed to identify different sedimentary environments of Gochang coast according to geomorphic conditions of each bore hole. To achieve the aim, this study utilized the classification of sedimentary environmental conditions of surface sediment, which was based on grain size distribution characteristics.In other words, three sedimentary environmental conditions ofsandy flat + sand beach, coastal sand dune and weathered bedrock soil, which were distinguished based on grain size distribution characteristics of mean-sorting for surface sediments, were applied to the sediments of bore holes. Four sedimentary environments could be identified in Gochang coast. First, the lake sedimentary environment originated from terrestrial sediments seems to have been dominated by weathered bedrock soil that the surface flow has deposited in a coastal wetland or a boundary, which is affected by the sea. Second, the lake sedimentary environment that is little affected by coastal sand dunes is located at the center of a valley, which is connected to the land, and the dune slack of Saban-ri. The surface flow of weather bedrock soil is the main source of deposits. However, there seems to have been a temporary influence of the sea. Third, the lake sedimentary environment that is strongly affected by coastal sand dunes is located at the dune slack of Yeongjeong-ri. This environment shows traces of a change from a coastal sand dune into the dune slack. Finally, the coastalsand dune sedimentary environment, which wasinvestigated by boring the current coastal sand dune, shows a temporary influence of the land but seems to have maintained the overall stability. Consequently, this study demonstrated that the grain size distribution characteristics of the present surface sediments could be effectively applied to identify the sedimentary environments of the paleo bore hole sediments. In addition, the paleo change of sedimentary environment could also be identified in many places of Gochang coast. If the results of this study are combined with the age dating and geochemical analysis in future works, the paleo environmental change in Gochang coast will be restored more precisely.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.198-207
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• 1999

Five core sediments acquired from the Lake Shihwa are analyzed for variations of sedimentary environment and heavy metal pollution after the Shihwa seawall construction. The depositional environment of the study area is divided into anoxic, oxic and mixed suboxic conditions based on the C/N ratio and C/S ratios of organic matters. Controlling factors for redox condition are the water depth and the difference in industrial effluents supply. Correlations among geochemical elements (Mn, U, Mo) show a distinctive difference and thus can be used as an indicator of redox condition. The content of Al, Ti are dependent on the sediment characteristics, and the contents of heavy metals (Cr, Ni, Cu, Zn, and Pb) indicate heavy metal pollution. The concentrations of heavy metals are higher near Shiswa-Banwol industrial complexies than the central part of Lake Shihwa. Especially, the accumulation of the heavy metal at the surface sediments near Shihwa-Banwol industrial complex are two to eight times higher than in the center of Lake Shihwa.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.43-50
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• 2013

The groundwater-surface water interaction of Searsville Lake area, California, US was analyzed using 3-dimensional groundwater model. This study especially focuses on investigating the groundwater head drawdown near the lake when the abrupt decline of the lake water table occurs due to the implementation of the options to remove the accumulated sediments along the dam. The result of the investigation revealed that the groundwater head drawdown near the lake is not significant enough to adversely affect the wetland habitat of the area regardless of the hydrogeologic parameters of the aquifers. We expect this result provides useful information to the similar Korean case studies in which the surface water level abruptly changes due to the operation of the hydraulic gates of dams and wiers and the corresponding environmental impact should be considered.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.166-173
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• 2008

Chemical forms and release potential of heavy metals were studied in the lime treated sediment of lake Chungcho. Chemical forms of heavy metals were analyzed using a sequential extraction method, and release potential of heavy metals was evaluated by the ratio of the content of labile forms to total metal one. Dominant form of Cd, Cu, Pb, and Zn in the untreated sediments was organic/sulfidic form that is stable in the reducing environment such as the bottom of Lake Chungcho. With liming of the sediment, the chemical forms of studied metals were greatly changed from organic/sulfidic form to adsorbed and reducible form, especially Cd and Cu to adsorbed and reducible form, but Pb and Zn to reducible form. It is believed that increase of unstable form of heavy metals in the sediments by liming was caused by the increase of pH of the pore water at the expense of organic/sulfidic form. Thus, we concluded that the liming approach currently used in the treatment of dredged sediments might cause the increase of labile form which is easily dissolved, and may increase the release of metals from the sediment into overlying water.

• Economic and Environmental Geology
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• v.30 no.3
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• pp.209-222
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• 1997

The Hoenam area, up the Taecheong lake, composed mainly of low grade coal-bearing metapelites within the Ogcheon Supergroup. These coal formations are developed discontinuously several hundred meters and swelling from 10 to 300 cm along the host metapelites. Although the formations have been mined for coal, but already mined out, and the formations were higher content (mean value of 42 samples) of environmental toxic elements as As (13 ppm). Ba (1.81 wt. %), Cd (2 ppm), Cr (188 ppm), Cu (87 ppm), Mo (214 ppm), Pb (25 ppm), Sb (3 ppm), Se (12 ppm), U (55 ppm), V (2124 ppm) and Zn (234 ppm) than the host metapelites and the NASC. The Al, Ti, Mg, K and Na contents in stream sediments derived from the Hando and Bugook mine area were highly concentrations than the samples from the Samseongjeil mine area. The mean value (wt. %) of Fe (10.07), Mn (0.15), Ca (0.84), P (0.18) and Ba (0.77) influenced by the Samseongjeil mine were higher than the other mine drainage sediments. The mean content (ppm) of environmental toxic elements in drainage sediments from the Samseongjeil mine were taken As (2083), Cu (447), Mo (202), Ni (720), Pb (42), U (250), V (1070) and Zn (2632), which are extremely high concentrations against NASC and EPA. Characteristics of elemental behavior and dispersion of the all toxic elements are the same as increased with increasing U, V, and Cu. Rare earth elements in the sediments are enriched with LREE (La, Ce and Nd) from the drainage on strong concentration of toxic elements. The pH of stream water is neutral, but pH of the sediments ranged from 4.92 to 6.93 (mean 6.22), those are slightly acid in the Hando mine area. Major elements in the host rocks at the Hoenam area are mostly depleted especially Ca, excepting Ti and Ba, normalized with NASC. The sediments were highly enriched of Ti, Fe, Mg, Mn and Ba, but depleted of Al, K, Ca, Na and P on the basis of host rocks and NASC. Minor and environmental toxic elements in the host rocks were strongly enriched all elements (As, Cd, Mo, Se, D, V and Zn), excepting Co, Ni and Sr. Enrichment index (mean value) about toxic elements (As, Cr, Cu, Fe, Ni, Pb and Zn) of the sediments in this area have taken 41.35 (Hando mine drainage; 2.73, Samseongjeil mine drainage; 113.14 and Bugook mine drainage; 8.19), those are seriously contaminated by environmental toxic elements.