• The Korean Journal of Quaternary Research
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• v.24 no.2
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• pp.35-48
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• 2010

The purpose of this study is to investigate paleoenvironmental conditions of the shallow sea around Jeju Island during the Late Holocene using geochemical contents of the bivalve (Glycymeris albolineata) collected from the Sangmori Shell Mound. The bivalve shell used shows the archaeological age of 2,300 yr BP. Stable carbon and oxygen isotope compositions show that growth rates decreased with aging. Coeval trends of both isotope compositions can be observed: heavier values during winters and lighter values summers except for their young and old growth stages. The seasonality of bivalve shell appear to reflect seasonal variations of paleotemperature as well as paleosalinity. Especially China Coastal Water with low salinity was transported into the southern Jeju Strait from Changjiang River during summer periods. Heavier carbon isotope values during winter indicate higher productivity, and this is supported by high density of phytoplanktons and higher chlorophyll contents during winter time. For accurate interpretation, monitoring of present-day conditions of shallow marine water as well as additional geochemical analysis of the same Recent bivalve may be necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6567-6574
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• 2015

In order to estimate the characteristics of the growth and composition of phytoplankton according to the available nutrients, we added nitrate (0, 1, 5, 10, 20, 50, $100{\mu}M$) and phosphate (0, 0.1, 0.5, 1, 2, 5, $10{\mu}M$) to field samples in a eutrophic site (St. 1) and an oligotrophic site (St. 22) in 2010 as well as a eutrophic site (St. 1, 5), a mesotrophic site (St. 19), and an oligotrophic site (St. 22) in 2011 at Jinhae Bay, Korea. The phytoplankton growth in the areas with additional nitrates and phosphates on St. 1 were significantly different from the control (One-way ANOVA:P<0.01). The dominant species at St. 1 in 2010 were Heterocapsa triquetra and Pseudo-nitzchia spp., to which nitrate and phosphate were added, respectively. The dominant species at St. 22 in 2010 differed between treatment conditions as follows: nitrate treatment Chaetoceros spp. (${\leq}10{\mu}M$), Thalassiosira spp. ($20{\mu}M$), and Pseudo-nitzchia spp.(${\geq}50{\mu}M$) for nitrate treatment; Cylindrotheca spp. ($2{\mu}M$) and Pseudo-nitzchia spp. ($5{\mu}M$) for phosphate treatment. Phytoplankton growth in 2011 according to the added nutrient were significantly different with treatment concentrations (One-way ANOVA: P<0.01). Moreover, the beginning of exponential growth in phytoplanktons was different between the eutro-mesotrophic sites (St. 1, 5, and 19) and the oligotrophic sites (St. 22) on day 2 and day 6 respectively. This implies that phytoplankton growth in the low nutrient condition may be retarded. The dominant species at St. 1 were Eucampia spp. and Chaetoceros spp. in the low nutrient treatment compared to Skeletonema spp., and Thalassiosira spp in the high nutrient treatment. The dominant species at St. 5 and St. 19 were mostly Skeletonema spp. and Chaetoceros spp. However, the dominant species at St. 22 was Thalassiosira spp.. The results of this study showed that phytoplankton growth and composition were different in areas with different nutrient characteristics resulting from the additional nutrients. Therefore, the nutrients additional algal assay could be indirectly explained why the biomass and composition of phytoplankton in Jinhae Bay has shown spatial differences.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.271-283
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• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.9-21
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• 2011

This study is conducted to know the change in water environment of Lake Hwajinpo from 2000 to 2008 with physico-chemical parameters; salinity, dissolved oxygen, total phosphorus and total nitrogen and others. And zooplanktons and phytoplanktons were studied from 2007 to 2008. From the water quality data of Lake Hwajinpo from 2000 to 200S; water temperature, salinity, transparency, chemical oxygen demand and dissolved oxygen ranges are $2.8{\sim}29.4^{\circ}C$, 0.23~33.2‰, $0.2{\sim}1.8\;m$, $0.2{\sim}20.2\;mg\;L^{-1}$ and $0.1{\sim}17.4\;mg\;L^{-1}$ and the average values are $18.0^{\circ}C$, 15.7‰, 0.7 m, $5.7\;mg\;L^{-1}$ and $8.0\;mg\;L^{-1}$, respectively. Total phosphorus (TP) and total nitrogen (TN) ranges are $0.024{\sim}0.869\;mg\;L^{-1}$ (average 0.091) and $0.240{\sim}5.310\;mg\;L^{-1}$ (average 1.235). Average TN/TP ratio is 16.4. The annual variations in COD, TP, TN and Chl.${\alpha}$ are compared. COD in 2000 is $4.83\;mg\;L^{-1}$ and 2008 is $1.80\;mg\;L^{-1}$ which is reduced by $0.34\;mg\;L^{-1}$ every year. TP in 2000 is $0.07\;mg\;L^{-1}$ and 2008 is $0.05\;mg\;L^{-1}$ reduced gradually. Yearly reduction in TN is $0.09\;mg\;L^{-1}$, in 2000 and 2008 the values are $1.54\;mg\;L^{-1}$ and $0.77\;mg\;L^{-1}$ respectivly. Chl.${\alpha}$ in 2000 is $46.30\;{\mu}g\;L^{-1}$ and $5.78\;{\mu}g\;L^{-1}$ in 2008; yearly reduction is $4.50\;{\mu}g\;L^{-1}$. The tropic state index (TSI) in south and north parts of Lake Hwajinpo in 2000 are 67 and 63 which are reduced to 63 and 59 in 2008 respectively. North and south part of Lake Hwajinpo have 67 species of phytoplankton under 47 families in 2007 and 2008. Dominant species in south part in 2007 are; Asterococcus superbus in May, Lyngbya sp. in September and Trachelomonas spp. in November and in 2008 Anabaena spiroides in August are abundant and varies with time. Zooplankton species in Lake Hwajinpo are 25 of 25 families. Dominant species in south part in May and August 2007 and May and November in 2008 Copepoda larvae and in September 2007 Protozoa spp. of Protozoan and Brachionus plicatilis and Brachionus urceolaris of Cladocera in August 2008. Dominant species in north part Asplanchna sp. of Cladecera in August and November 2007 and rest of the time are larvae of Copepoda. In this way, the water quality of Lake Hwajinpo is changing with slow rate in the long period specially nutrients concentration (TP, TN etc) is decreasing.