• Journal of Korean Society of Disaster and Security
• /
• v.16 no.4
• /
• pp.45-59
• /
• 2023

The global focus on mitigating climate change has traditionally centered on carbon dioxide, but recent attention has shifted towards methane as a crucial factor in climate change adaptation. Natural settings, particularly aquatic environments such as wetlands, reservoirs, and lakes, play a significant role as sources of greenhouse gases. The accumulation of organic contaminants on the lake and reservoir beds can lead to the microbial decomposition of sedimentary material, generating greenhouse gases, notably methane, under anaerobic conditions. The escalation of methane emissions in freshwater is attributed to the growing impact of non-point sources, alterations in water bodies for diverse purposes, and the introduction of structures such as river crossings that disrupt natural flow patterns. Furthermore, the effects of climate change, including rising water temperatures and ensuing hydrological and water quality challenges, contribute to an acceleration in methane emissions into the atmosphere. Methane emissions occur through various pathways, with ebullition fluxes-where methane bubbles are formed and released from bed sediments-recognized as a major mechanism. This study employs Biochemical Methane Potential (BMP) tests to analyze and quantify the factors influencing methane gas emissions. Methane production rates are measured under diverse conditions, including temperature, substrate type (glucose), shear velocity, and sediment properties. Additionally, numerical simulations are conducted to analyze the relationship between fluid shear stress on the sand bed and methane ebullition rates. The findings reveal that biochemical factors significantly influence methane production, whereas shear velocity primarily affects methane ebullition. Sediment properties are identified as influential factors impacting both methane production and ebullition. Overall, this study establishes empirical relationships between bubble dynamics, the Weber number, and methane emissions, presenting a formula to estimate methane ebullition flux. Future research, incorporating specific conditions such as water depth, effective shear stress beneath the sediment's tensile strength, and organic matter, is expected to contribute to the development of biogeochemical and hydro-environmental impact assessment methods suitable for in-situ applications.

• Korean Journal of Heritage: History & Science
• /
• v.57 no.1
• /
• pp.162-178
• /
• 2024

Swans are representative migratory birds that spend winter in East Asia, and have long been considered rare birds. In particular, they were regarded as king of Japan. The process of designating a natural monument in Hapcheon Swan Sanctuary is an interesting story. In this study, the designation and release process of Hapcheon Swan Sancturay ((Bakgok-ji, Yongju-myeon 龍州面 朴谷池), (Jeongyang-ji, Daeyang-myeon 大陽面 正陽池), Gaho, Cheongdeok-myeon 淸德面 嘉湖)) Natural Monument, was examined. These places were designated as a natural monument on August 27, 1934, during the Japanese colonial period, and was lifted on August 14, 1973, after the Cultural Protection Act was enacted after liberation. From the beginning of the new year in 1929, the Japanese Government-General of Korea (朝鮮總督府) decided to capture swans alive to give to the king of Japan. An official of the Japanese Government-General of Korea (統監) decided to offer swans to the king during his New Year's greeting visit. The department in charge of capturing swans was the Gyeongsangnam-do Provincial Police Department, and the execution was the police station of each county (郡). The reason is believed to be that it is easy to forcibly mobilize, control, or urge people, and the capture activity had to be completed as soon as possible. A total of three swans were captured in Hapcheon-gun from January 12 to 14, 1929. At that time, various newspapers published related information. Based on these facts and experiences, it is estimated that the Hapcheon area was selected when designating a natural monument in 1934. Hapcheon Swan Sancturay, Natural Monument lost its function due to excessive human interference of various developments, illegal capture, and use of poison to catch swans. Their number has also significantly decreased. It was thus removed from the natural monument in 1973. One of the three swan sanctuaries (Gaho 嘉湖) has been completely reclaimed, one (Bakgok-ji 朴谷池) has almost no migratory birds due to the conversion of wetlands, and one (Jeongyang-ji 正陽池) has swans flying back. In the case of Jeongyangji (正陽池), It is an encouraging sign that many swans fly as the surrounding environment and growing conditions change. This phenomenon is interpreted to mean that nature and climate are recovering and healing.