• Title/Summary/Keyword: DO meter

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Seasonal Variation of Water Quality in a Shallow Eutrophic Reservoir (얕은 부영양 저수지의 육수학적 특성-계절에 따른 수질변화)

  • Kim, Ho-Sub;Hwang, Soon-Jin
    • Korean Journal of Ecology and Environment
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    • v.37 no.2 s.107
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    • pp.180-192
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    • 2004
  • This study was carried out to assess the seasonal variation of water quality and the effect of pollutant loading from watershed in a shallow eutrophic reservoir (Shingu reservoir) from November 2002 to February 2004, Stable thermocline which was greater than $1^{\circ}C$ per meter of the water depth formed in May, and low DO concentration (< 2 mg $O_2\;L^{-1}$) was observed in the hypolimnion from May to September, 2003. The ratio of euphotic depth to mixing depth ($Z_{eu}/Z_{m}$) ranged 0.2 ${\sim}$ 1.1, and the depth of the mixed layer exceeded that of the photic layer during study period, except for May when $Z_{eu}$ and $Z_{m}$ were 4 and 4.3 m, respectively. Most of total nitrogen, ranged 1.1 ${\sim}$ 4.5 ${\mu}g\;N\;L^{-1}$, accounted for inorganic nitrogen (Avg, 58.7%), and sharp increase of $NH_3$-N Hand $NO_3$-N was evident during the spring season. TP concentration in the water column ranged 43.9 ${\sim}$ 126.5 ${\mu}g\;P\;L^{-1}$, and the most of TP in the water column accounted for POP (Avg. 80%). During the study period, DIP concentration in the water column was &;lt 10 ${\mu}g\;P\;L^{-1}$ except for July and August when DIP concentration in the hypolimnion was 22.3 and 56.7 ${\mu}g\;P\;L^{-1}$, respectively. Increase of Chl. a concentration observed in July (99 ${\mu}g\;L^{-1}$) and November 2003 (109 ${\mu}g\;L^{-1}$) when P loading through two inflows was high, and showed close relationship with TP concentration (r = 0.55, P< 0.008, n = 22). Mean Chl. a concentration ranged from 13.5 to 84.5 mg $L^{-1}$ in the water column, and the lowest and highest concentration was observed in February 2004 (13.5 ${\pm}$ 1.0 ${\mu}g\;L^{-1}$) and November 2003 (84.5 ${\pm}$29.0 ${\mu}g\;L^{-1}$), respectively. TP concentration in inflow water increased with discharge (r = 0.69, P< 0.001), 40.5% of annual total P loading introduced in 25 July when there was heavy rainfall. Annual total P loading from watershed was 159.0 kg P $yr^{-1}$, and that of DIP loading was 126.3 kg P $yr^{-1}$ (77.7% of TP loading. The loading of TN (5.0ton yr-1) was 30 times higher than that of TP loading (159.0 kg P yr-1), and the 78% of TN was in the form of non-organic nitrogen, 3.9 ton $yr^{-1}$ in mass. P loading in Shingu reservoir was 1.6 g ${\cdot}$ $m^{-2}$ ${\cdot}$ $yr^{-1}$, which passed the excessive critical loading of Vollenweider-OECD critical loading model. The results of this study indicated that P loading from watershed was the major factor to cause eutrophication and temporal variation of water quality in Shingu reservoir Decrease by 71% in TP loading (159 kg $yr^{-1}$) is necessary for the improvement of mesotrophic level. The management of sediment where tine anaerobic condition was evident in summer, thus, the possibility of P release that can be utilized by existing algae, may also be considered.

The Establishment of Seongjusa Temple and the Production of Iron Buddhas (성주사 창건과 철불 조성 연구)

  • Kang Kunwoo
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.104
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    • pp.10-39
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    • 2023
  • Seongjusa Temple was founded in Boryeong in Chungcheongnam-do Province by Monk Muyeom (800-888), better known as Nanghye Hwasang. After returning from studying in China, Muyeom stayed in the Silla capital city of Gyeongju for a period. He later settled in a temple that was managed by the descendants of Kim In-mun (629-694). He then restored a burned-out temple and opened it in 847 as a Seon (Zen) temple named Seongjusa. It prospered and grew to become a large-scale temple with several halls within its domains. The influence of Seongjusa in the region can be seen in the Historical Record of Seongjusa Temple on Sungamsan Mountain, which relates that there were seventy-three rooms within the domains of the temple. What is most notable in the record is that the temple is referred to as "栴檀林九間," which means either "a structure with nine rooms built with Chinese juniper wood" or "a place that houses Chinese juniper wood and has nine rooms." Regardless of the interpretation, Seongjusa Temple had a large amount of juniper wood. Around this time, the term "juniper" referred to the olibanum tree (Boswellia sacra) native to the islands of Java and Sumatra in Southeast Asia. It is presumed that at some point after the death of Jang Bogo, the maritime forces that controlled the southwestern coast of Korea may have acquired a large amount of Southeast Asian olibanum wood and offered it to Seongjusa Temple. During the reign of King Munseong, Kim Yang (808-857) patronized Seongjusa Temple and its head monk Muyeom, who enjoyed a lofty reputation in the region. He sought to strengthen his own position as a member of the royal lineage of King Muyeol and create a bridge between the royal family and Seongjusan Buddhist sect. The court of King Wonseong designated Seongjusa Temple as a regional base for the support of royal authority in an area where anti-royal sentiment remained strong. Monk Muyeom is believed to have created an iron Buddha to protect the temple, enlighten the people, and promote regional stability. Given that the Seongjusa community had expanded to include more than 2,000 followers, the iron Buddha at Seongjusa Temple would have been perceived as an image that rallied the local residents. It is assumed that there were two iron Buddhas at Seongjusa Temple. The surviving parts of these Buddhas and the size of their pedestals suggest that they were respectively enshrined in the Geumdang Main Hall and the Samcheonbuljeon Hall of Three Thousand Buddhas. It is presumed that the first iron Buddha in Geumdang was a large statue over two meters in height and the second one was medium-sized with the height over one meter. The Historical Record of Seongjusa Temple on Sungamsan Mountain contains the phrase "改創選法堂五層重閣" which indicates that a multistoried Geumdang was newly built to enshrine a large Buddha sculpture like the first iron Buddha when Seongjusa Temple was founded. Also, according to the Stele of Seongjusa Temple and the surviving finger fragments, the first Buddha was making the fear-not and wish-granting (abhayavarada) mudras. The main Buddha of Seongjusa Temple is possibly Nosana Buddha, just like the main Buddhas at the contemporaneous temples Silsangsa, Borimsa, and Samhwasa. Given that Monk Muyeom studied Hwaeom teachings in his early years and received royal patronage upon his return, it is believed that the retro tendencies of the Hwaeom school, centered on the royal family of the Silla Dynasty, were reflected in Seongjusa temple.