A Study on the Development of Deep Seabed Mineral Resources Exploration Techniques and Protection of Deep-Sea Environment

과학기술

The Role of Oceanography on the underwater cultural heritage

2

Sediment-Water Interface Flux of Methane in the Gunsan Basin of the South-Eastern Yellow Sea, Off the Coast of Western Korea

The sediment1

SWI Flux of CH4 in the Gunsan Basin of the South-Eastern Yellow Sea, Off the Coast of Western Korea

The sediment&#8211 water interface (SWI) flux of methane (CH4) was investigated using Fick’s first law of diffusion in box cores from eight stations in the Gunsan Basin, the south-eastern part of the Yellow Sea, in 2015 [1]. The dissolved CH4 concentrations in the samples were measured using a gas chromatograph&#8211 semiconductor detector (EG Analyzer, model GS-23 Sensortec, Inc., Shiga, Japan) by injecting an aliquot of headspace gas [2]. The CH4 flux of the SWI in the Gunsan Basin ranges from 0.002 to 0.029 (average 0.012) mM·m-2·day-1. The average CH4 emission flux over the total area of the Gunsan Basin (60,000 km2 [3]) is 11.8 ton·year-1. This value is lower compared with those in other parts of the world. The range of CH4 flux is higher than the 0.007&#8211 0.01 mM·m-2·day-1 observed in Tomales Bay, New York, USA, but much lower than those in intertidal zones, estuaries, and lakes [4]. To clearly predict the SWI flux of CH4, budget or modelling is recommended, together with more measurements of CH4 emission rates during field monitoring approaches in the Gunsan Basin of the South-Eastern Yellow Sea are required. [1] Martin et al. (2005) J. Control Release 102, 123-133. [2] Lee et al. (2018) J. Environ. Sci. Heal. A. 53, 457-466. [3] Wang et al. (2014) Geology of the China Seas 6, 392-393. [4] Sansone et al. (1998) Estuaries 21, 66-77.ellow Sea, in 2015 [1]. The dissolved CH4 concentrations in the samples were measured using a gas chromatograph&#8211 semiconductor detector (EG Analyzer, model GS-23 Sensortec, Inc., Shiga, Japan) by injecting an aliquot of headspace gas [2]. Discussion of Results The CH4 flux of the SWI in the Gunsan Basin ranges from 0.002 to 0.029 (average 0.012) mM·m-2·day-1. The average CH4 emission flux over the total area of the Gunsan Basin (60,000 km2 [3]) is 11.8 ton·year-1. This value is lower compared with those in other parts of the world. The range of CH4 flux is higher than the 0.007&#8211 0.01 mM·m-2·day-1 observed in Tomales Bay, New York, USA, but much lower than those in intertidal zones, estuaries, and lakes [4]. To clearly predict the SWI flux of CH4, budget or modelling is recommended, together with more measurements of CH4 emission rates during field monitoring approaches in the Gunsan Basin of the South-Eastern Yellow Sea are required.1

Gas release from tidal flat caused by decomposition of organic matter

갯벌 퇴적층으로부터 대기중으로 이산화탄소, 메탄가스의 방출량을 계산함으로서 갯벌의 유기물 분해및 지구온난화가스의 대기 방출 수지를 계산하고자, 2009년 4월 및 8월에 충남 근소만에서 2회 관측을 실시하였다.3개 측선에서 동.하계 주상시료 (60-80 cm)를 채취하여 퇴적층내 유기물 함량을 측정한 결과, 유기탄소의 함량이 E,S, W 측선에서 각각 0.21-0.39%, 0.18-0.96%, 0.08-0.67%로 나타났다. 측선별 함량의 차는 퇴적상의 변화에 따라 크게 나타났으나, 유기물의 수직함량은 큰 변화를 나타내지 않았다. 근소만 갯벌 대기 (지상 1 m)중의 메탄농도는 1795-1930 ppbv였으며, 퇴적층으로부터 방출되는 메탄의 플럭스는 0.15-0.63 mmol/m^2d로 나타났다.2

곰소만 만돌, 하전, 상암 퇴적물의 In-Situ Air Sparging 공법을 이용한 PAHs의 농도 감소 변화

본 논문은 전라북도 부안∙고창 지역에 위치한 곰소만 만돌리(Sand), 하전리(sandy Silt), 상암리 (Silt) 지역 퇴적물 및 부산항 근처 준설토 샘플(Clay)을 이용한 PAHs(polycyclic aromatic hydrocarbons)의 농도 감소 변화의 실험실 규모 연구(lab scale)이다. 응용 적용된 기술방법은 공기주입(In-Situ Air sparging)법으로 포화층(vadose zone)에 있는 오염물질을 지중으로 처리하는 기술이다. 이 기술은 대수층에 있는 휘발성유기화합물(volatile organic compounds; VOCs)과 석유계 탄화수소류(total petroleum hydrocarbons; TPHs)를 효과적으로 처리하며 이는 포화 퇴적물층으로 직접 압을 가해 공기 주입한다. 이런 유기적인 물질을 공기로 상승시켜 포화층(vadose zone)으로부터 불포화층(unsaturated zone)으로 VOCs 물질들을 휘발시키는 복원기술을 말한다. 이러한 실험 결과는 항후 다양한 입도상을 가진 국내 오염퇴적물 및 해양 준설토 복원 및 오염저감 계획수립에 있어 PAHs(polycyclic aromatic hydrocarbons)의 농도 감소 양상을 파악하는데 있어 기초자료로 활용될 수 있을 것으로 판단된다. 실내 실험에 사용될 곰소만내 대표 표층퇴적물 3정점의 샘플 및 부산항 근처 준설 퇴적물 1정점에서 샘플을 채취하였다. 샘플링 후 기본적인 입도(mean size), 함수율, 전밀도 및 유기탄소(total organic carbon; TOC) 항목등을 분석 후 120℃에 12시간동안 건조 후 2 mm 체에 거른 다음 각각 지역의 건조한 퇴적물과 MIX-1 혼합액은 1:1 비율로 섞은 뒤 48시간 지난 후 실내 실험 분석에 사용하였다. 각 컴럼에 주입된 공기압은 90 psi의 압력 및 0-5 L/min 유량으로 48시간 공기주입(In-Situab scale)이다. 응용 적용된 기술방법은 공기주입(In-Situ Air sparging)법으로 포화층(vadose zone)에 있는 오염물질을 지중으로 처리하는 기술이다. 이 기술은 대수층에 있는 휘발성유기화합물(volatile organic compounds; VOCs)과 석유계 탄화수소류(total petroleum hydrocarbons; TPHs)를 효과적으로 처리하며 이는 포화 퇴적물층으로 직접 압을 가해 공기 주입한다. 이런 유기적인 물질을 공기로 상승시켜 포화층(vadose zone)으로부터 불포화층(unsaturated zone)으로 VOCs 물질들을 휘발시키는 복원기술을 말한다. 이러한 실험 결과는 항후 다양한 입도상을 가진 국내 오염퇴적물 및 해양 준설토 복원 및 오염저감 계획수립에 있어2

THE DIFFERENT IMPACTS OF HUMAN SOURCES ON THE SPATIAL DISTRIBUTION OF PAHs AND PCBs IN SURFACE SEDIMENTS IN THE NAKDONG RIVER ESTUARY, SOUTH KOREA

The Nakdong River in South Korea is about 510 km long and is exposed to various potential sources of human pollution, such as urban dumping, industrial complexes, and input from many cities. The Noksan Dam, built in 1934, blocks the flow of the West Nakdong River, while the NRE Dam was completed in 1987 to regulate flow from the East Nakdong River. This study assessed the concentrations and trends of persistent contaminants in surface sediments, including 16 polycyclic aromatic hydrocarbons (PAHs) and 19 polychlorinated biphenyls (PCBs), and examined their origins. Eighteen surface sediment samples were collected on and around the barrier islands (Eulsukdo, Jinwoodo, and Sinjado) and near the Nakdonggang Estuary Bank from May 2015 to August 2016. The concentrations of PAHs (10.8&#8211 1,079.6 ng·g-1) and PCBs (197.0&#8211 1,131.0 pg·g-1) in the surface sediments revealed different spatial patterns for these compounds, suggesting that they partially originated from the use of commercial PCB products in adjacent industrial complexes. The analysis determined that PAHs originated from the combustion of fossil fuels and biomass, and the overall concentrations due to anthropogenic activity were related to the contributions of individual PAHs in most of the sediment samples. Compared to the sediment quality guidelines of the National Oceanic and Atmospheric Administration (NOAA) for PAHs and PCBs, they were less enriched the West Nakdong River, while the NRE Dam was completed in 1987 to regulate flow from the East Nakdong River. This study assessed the concentrations and trends of persistent contaminants in surface sediments, including 16 polycyclic aromatic hydrocarbons (PAHs) and 19 polychlorinated biphenyls (PCBs), and examined their origins. Eighteen surface sediment samples were collected on and around the barrier islands (Eulsukdo, Jinwoodo, and Sinjado) and near the Nakdonggang Estuary Bank from May 2015 to August 2016. The concentrations of PAHs (10.8&#8211 1,079.6 ng·g-1) and PCBs (197.0&#8211 1,131.0 pg·g-1) in the surface sediments revealed different spatial patterns for these compounds, suggesting that they partially originated from the use of commercial PCB products in adjacent industrial complexes. The analysis determined that PAHs originated from the combustion of fossil fuels and biomass, and the overall concentrations due to anthropogenic activity were related to the contributions of individual PAHs in most of the sediment samples. Compared to the sediment quality guidelines of the National Oceanic and Atmospheric Administration (NOAA) for PAHs and PCBs, they were less enriched1

Summer-Time Behaviour and Flux of Suspended Sediments at the Entrance to Semi-Closed Hampyung Bay, Southwestern Coast of Korea

반폐쇄형의 함평만 입구를 가로지르는 두 개의 정점(H1, H2)에서 1999년 8월 12-13일 대조기에 각각 한 조석주기동안 물리적 특성과 부유퇴적물의 농도변화에 대한 정선관측을 실시하였다. 수온과 염분의 조석변화는 각각 26.0-27.9 ∘C , 30.9-31.5 범위에서 창조시 저온과 고염분의 외해수 그리고 낙조시 고온과 저염분의 연안수 특성을 보이며, 복사열이 강한 여름철임에도 불구하고 강한 조류의 혼합작용으로 인해 수괴의 수직적 혼합이 잘 이루어지고 있다. 부유퇴적물의 농도는 표층에서 낮고 저층으로 향하면서 높아지며 수층별로 뚜렷한 차이를 보이고 있다. 불량한 분급도를 보이는 부유퇴적물은 대부분 극세립- 세립실트(>40%)로 구성되어 있는 가운데, 점토 크기 이하( μm )의 세립자들은 에너지가 약한 정조시에 상호간의 결합을 통해 입자 덩어리를 형성하고 있다. 조석별 평균유속의 세기는 남서쪽 정점 H1의 경우 낙조류가 창조류에 비해 수층에 따라 23-59 % 우세한 반면, 정점 H2에서는 오히려 창조류가낙조류에 비해 27-37 % 우세한 비대칭성을 보이고 있다. 이에 따른 각 정점에서 계산된 잔여유속은 정점 H1에서 아주 큰 값(-10 ∼ -20 cm s−1 )으로 외해쪽으로 향하고 있는 반면, 정점 H2에서는 내만쪽으로 향하는 미약한 흐름( s−1 )이 존재한다. 한편, 부유퇴적물의 농도변화는 남서쪽(H1)에서 낙조시에 비해 창조류를 따라 외해로부터 유입되는 양이 많고, 정점 H2에서는 창조시에 비해 낙조류를 따라 외해로 유출되는 양이 훨씬 높게 나타나고 있다. 잔여유속과 부유퇴적물의 농도를 고려한 부유퇴적물의 순이동률( fs )은 모든 정점에서 수층에 따라 -1.7 ∼ -15.6 × 10−3 kg m−2 s−1 속도로 일관되게 외해쪽으로 향하고 있으며, 북동쪽에서 보다 빠른 이동률을 보이고 있다. 부유퇴적물의 순이동량( \cQs )은 정점 H1과 H2에서 각각 0.37 × 103 , 0.21 × 103 kg m−1 의 양이 여름철 대조기 한 조석주기동안에 외해로 빠져나가고 있는 것으로 나타났다. 함평만 입구에서 여름철임에도 불구하고 부유퇴적물이 외해쪽으로 이동되고 있는 것은 내만에 발달되어 있는 조간대의 침식을 의미하는 것으로서, 지금까지 서해안 조간대에서 보고되고 있는 일반적인 여름철 퇴적현상과는 상이한 결과를 나타내고 있다. Anchored measurements (12.5 hr) of suspended sediment concentration and other hydrodynamic parameters were carried out at two stations located at the entrance to Hampyung Bay in summer (August 1999). Tidal variations in water temperature and salinity were in the range of 26.0-27.9 ∘C and 30.9-31.5, respectively, indicating exchange offshore and offshore water mass. Active tidal mixing processes at the entrance appear to destroy the otherwise vertical stratification in temperature and salinity in spite of strong solar heating in summer. On the contrary, suspended sediment concentrations show a marked stratification with increasing concentrations toward bottom layer. Clastic particles in suspended sediments consist mostly of very fine to fine silt (4-16 μ m) with a poorly-sorted value of 14.7-25.9 μ m. However, at slack time with less turbulent energy, flocs larger than 40 μ m are formed by cohesion and inter-collision of particles, resulting in a higher settling velocity. Strong ebb-dominated and weak flood dominated tidal currents, in the southwestern and the northeastern part, respectively, result in a seaward residual flow of -10 ∼ -20 cm s−1 at station H1 and a bayward residual flow less than 5.0 cm s−1 at station H2. However, mean concentration of suspended sediments at station H1 is higher at flood (95.0-144.1 mg 1−1 ) than in ebb (75.8-120.9 mg 1−1 ). On the contrary, at the station H2, the trend is reversed with higher concentration at the ebb (84.7-158.4 mg 1−1 ) than that at the flood (53.0-107.9 mg 1−1 ). As a result, seaward net suspended sediment fluxes ( fs ) are calculated to be -1.7 ∼ - 15.6103 kg m−2 s−1 through the whole water column. However, the stations H1 and H2 show definitely different values of the flux with higher ones in the former than in the latter. Alternatively, depth-integrated net suspended sediment loads ( \cQs ) for one tidal cycle are also toward the offshore with ranges of 0.37 × 103 kg m−1 and 0.21 × 103 kg m−1 , at station H1 and H2, respectively. This seaward transport of suspended sediment in summer suggests that summer-time erosion in the Hampyung muddy tidal flats is a rather exceptional phenomenon compared to the general deposition reported for many other tidal flats on the west coast of Korea.33Nkciothe

Total Volatile Organic Compounds (Benzene, Toluene, Ethylbenzene, and Xylene) Surface Sediments from Barrier Islands in the Nakdong River Estuary, South Korea

The total volatile organic compound (TVOC) concentrations and distribution were determined for 18 surface sediment samples collected in and around three islands in the Nakdong River estuary, in the southeastern Korean Peninsula on May 2015. There are four primary volatile organic compounds: benzene, toluene, ethylbenzene, and xylene. The emissions of TVOCs from sediments were measured using a thermal desorption system-gas chromatograph-mass selective detector (TDS-GC-MSD) for 30 min at 25°C in the National Center for Inter-University Research Facilities, South Korea. The thermal extractor (Gerstel, Germany) was equipped with an adjustable oven (temperature 20&#8211 350°C) to heat a glass tube containing the sample. The TVOC ranged from 2.6 to 64.9 ng/g-dry wt (average, 13.2 ± 13.8 ng/g-dry wt), with benzene 0.6 to 0.8 ng/g-dry wt (average, 0.7 ± 0.1 ng/g-dry wt), toluene 0.4 to 1.3 ng/g-dry wt (average, 0.9 ± 0.3 ng/g-dry wt), and xylene 0.0 to 0.8 ng/g-dry wt (average, 0.2 ± 0.2 ng/g-dry wt). For most of the sampling stations, no evidence of ethylbenzene was found. The TVOC was highest for a Sinjado Island station, at 64.9 ng/g-dry wt. This area corresponds to backbarrier fringe marsh sediments sorted by location and terrain. Although the TVOC levels in many sediments were below the detection limits, this method can be used to estimate their behavior in marine environments. TVOCs in sediments are a major probl There are four primary volatile organic compounds: benzene, toluene, ethylbenzene, and xylene. The emissions of TVOCs from sediments were measured using a thermal desorption system-gas chromatograph-mass selective detector (TDS-GC-MSD) for 30 min at 25°C in the National Center for Inter-University Research Facilities, South Korea. The thermal extractor (Gerstel, Germany) was equipped with an adjustable oven (temperature 20&#8211 350°C) to heat a glass tube containing the sample. The TVOC ranged from 2.6 to 64.9 ng/g-dry wt (average, 13.2 ± 13.8 ng/g-dry wt), with benzene 0.6 to 0.8 ng/g-dry wt (average, 0.7 ± 0.1 ng/g-dry wt), toluene 0.4 to 1.3 ng/g-dry wt (average, 0.9 ± 0.3 ng/g-dry wt), and xylene 0.0 to 0.8 ng/g-dry wt (average, 0.2 ± 0.2 ng/g-dry wt). For most of the sampling stations, no evidence of ethylbenzene was found. The TVOC was highest for a Sinjado Island station, at 64.9 ng/g-dry wt. This area corresponds to backbarrier fringe marsh sediments sorted by location and terrain. Although the TVOC levels in many sediments were below the detection limits, this method can be used to estimate their behavior in marine environments. TVOCs in sediments are a major probl1

Relevance of methane flux on the intertidal flat sediments in Taean, west coast of Korea

The CH4 is a powerful greenhouse gas, third in importance to CO2 and H2O and is the most abundant hydrocarbon. The wetland has been known as a major biogenic source of CH4 in the atmosphere. In the global scale, the amounts of 55~150 Tg CH4 are released into the atmosphere annually from wetlands. From March 2013 to September 2014, the emission of major gases (CH4, CO2 and O2) was measured using closed static chamber method on the intertidal flat sediments at Sogeun-ri(36°48’ 52.3”N, 126°11’ 03.8”E) and Eoeun-ri(36°49’ 11.0”N, 126°19’ 19.0”E) in Taean. The average of gas flux at Sogeun-ri during the experimental period was +0.28 mg m-2 hr-1 (+0.06~+0.60 mg m-2 hr-1) for CH4, +75.72 mg m-2 hr-1 (+58.45~+95.58 mg m-2 hr-1) for CO2 and -0.08 mg m-2 hr-1 (-0.02~-0.20 mg m-2 hr-1) for O2. At Sogeun-ri, the CH4 flux to mean size of sediments and temperature of inner chamber exhibited strong positive correlation (R2=-0.97 and R2=-0.89, respectively). It may indicate that temperature have significant role in determining whether the CH4 and CO2 source or sink take place. The average of gas flux at Eoeun-ri during the experimental period was -0.02 mg m-2 hr-1 (-0.02~+0.02 mg m-2 hr-1) for CH4, -118.58 mg m-2 hr-1 (-137.00~-81.73 mg m-2 hr-1) for CO2 and -0.01 mg m-2 hr-1 (-0.03~+0.01 mg m-2 hr-1) for O2. At Eoeun-ri, the CH4 flux before low tide was -0.02 mg m-2 hr-1 (R2=-0.56). The CH4 flux after low tide reached are released into the atmosphere annually from wetlands. From March 2013 to September 2014, the emission of major gases (CH4, CO2 and O2) was measured using closed static chamber method on the intertidal flat sediments at Sogeun-ri(36°48’ 52.3”N, 126°11’ 03.8”E) and Eoeun-ri(36°49’ 11.0”N, 126°19’ 19.0”E) in Taean. The average of gas flux at Sogeun-ri during the experimental period was +0.28 mg m-2 hr-1 (+0.06~+0.60 mg m-2 hr-1) for CH4, +75.72 mg m-2 hr-1 (+58.45~+95.58 mg m-2 hr-1) for CO2 and -0.08 mg m-2 hr-1 (-0.02~-0.20 mg m-2 hr-1) for O2. At Sogeun-ri, the CH4 flux to mean size of sediments and temperature of inner chamber exhibited strong positive correlation (R2=-0.97 and R2=-0.89, respectively). It may indicate that temperature have significant role in determining whether the CH4 and CO2 source or sink take place. The average of gas flux at Eoeun-ri during the experimental period was -0.02 mg m-2 hr-1 (-0.02~+0.02 mg m-2 hr-1) for CH4, -118.58 mg m-2 hr-1 (-137.00~-81.73 mg m-2 hr-1) for CO2 and -0.01 mg m-2 hr-1 (-0.03~+0.01 mg m-2 hr-1) for O2. At Eoeun-ri, the CH4 flux before low tide was -0.02 mg m-2 hr-1 (R2=-0.56). The CH4 flux after low tide reached1