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Low-cost, multispectral machine learning classification of simulated airborne micro/nanoplastics
No full textThis study presents a novel smartphone-based, machine-learning-assisted multispectral classification method for identifying airborne micro- and nanoplastics (MNPs). Instead of commercial polymeric microspheres, coffee grinder-based cryogrinding generated nonuniform MNPs from real-world plastic products with highly irregular shapes and heterogenous size distributions. The low-cost handheld device comprises a smartphone, a spectral mask array made from plastic color films, and a discrete multiplexed illumination device. A stack of images was captured across multiple wavelength ranges, and the RGB ratios were extracted without using morphological information. An XGBoost model was trained on two datasets: dry and wet MNP samples passively collected on a glass slide, simulating two types of airborne MNPs. The model successfully distinguished plastics from clay with 89–99 % accuracy and classified six plastic types with 79–87 % accuracy for dry and wet MNPs. This method offers a promising toolkit for airborne MNP monitoring.11Nsciescopu
A GPU-accelerated numerical model for nearshore scalar transport by dispersive shallow water flows
No full textA GPU-accelerated nearshore scalar transport model with the Boussinesq-type wave solver is introduced. The depth-integrated advection-diffusion equation is implemented into Celeris Advent, the firstly-developed open-source Boussinesq wave model equipped with an interactive system supporting simultaneous visualization and data exchange between a user and the computing unit. A hybrid finite volume-finite difference scheme is adopted to discretize the governing equations, and the modified HLL Riemann solver for satisfying the conservation property of the scalar concentration is applied for an accurate approximation of scalar numerical flux. A source-function wavemaker in conjunction with alongshore periodic boundary conditions and a wave-breaking model are implemented to more precisely replicate the nearshore hydrodynamic processes. Several numerical tests using analytical solutions and experimental data are performed to validate the model. Finally, field-scale dye release experiments are reproduced numerically, assessing the applicability of the proposed model in predicting nearshore scalar transport by dispersive hydrodynamics. The proposed model is expected to serve as an advanced tool for real-time assessment and mitigation of marine pollution incidents.11Nsciescopu
AUTOMATED DETACHABLE TYPE SUCTION ANCHOR SYSTEM WITH MULTIPLE PUMP
No full text자동 착탈식 석션 시스템으로 대용량 펌프와 고양정의 펌프로 해저 지반의 변화에 따른 펌프의 선택으로 석션파일의 관입을 원활하게 할 수 있다. 무용접형 고하중 프레임으로 중량물의 석션파일을 인양시 안정성을 높일 수 있다. 공기빼기 개폐구 및 클램프를 직선형 실린더를 사용함으로써 저압의 수압으로 작업할 수 있으며, 개폐구의 크기의 증가에도 압력 증가 없이 밸브 작동이 가능하다. 또한 시스템을 단순화함으로써 시스템 크기 및 고장 발생의 원인을 줄임으로써 작업의 안정성 및 효율성을 극대화 할 수 있다
Analysis of regional variation of water transparency in the Yellow Sea and East China Sea based on MODIS data
No full textWater transparency is an important optical parameter used to interpret various properties related to water quality. We investigated regional variation in water transparency in the Yellow Sea (YS) and East China Sea (ECS) by conducting linear regression and k-means clustering analyses based on satellite-derived water transparency data and satellite products including MODIS sea surface temperatures (SSTs) and chlorophyll a concentration (Chl), colored dissolved organic matter (CDOM), and total suspended matter (TSM) levels for the period 2003–2023. Water transparency showed seasonal variation, increasing in summer and decreasing in winter, with larger seasonal extremes observed in the central YS and around Jeju Island than in coastal waters of Korea and China. Decadal variation in water transparency was significantly higher in summer and autumn than in spring and winter throughout the study area, exhibiting an increasing trend that was strongly correlated with decreasing Chl, CDOM, and TSM levels. K-means analysis resulted in the selection of five regions in the YS and ECS, among which spatial and temporal variation in water transparency were related to different regional impact factors. Coastal waters of Korea and China and the southern YS displayed a weaker increase in water transparency, which was associated mainly with Chl, followed by TSM and CDOM. In contrast, water transparency tended to increase dramatically in the central YS, where decadal variation was associated mainly with changes in TSM, followed by Chl and CDOM levels. Thus, regional variation in water transparency in the study area was dependent on local water conditions. These findings will be useful for understanding regional water quality in the study area.11Nsciescopu
Geographical Subdivision of the Hydrothermal Vent Bythograeid Crabs in the Indian Ocean
No full textBrachyuran crabs of the genus Austinograea are the endemic species of the deep-sea hydrothermal vents with widespread distribution in the western Pacific and the Indian Ocean. To date, only one species was reported in the Indian Ocean, Austinograea rodriguezensis. In this study, we investigated the population connectivity of bythograeid crabs of the genus Austinograea in the Indian Ocean. Mitochondrial COI sequences were collected from the seven vent fields. The bythograeid crabs were separated geographically into northern and southern groups, which showed high level of genetic distance (>5% in COI gene) between them. Each group had a high sequence similarity (>99%) with A. rodriguezensis and undescribed Austinograea species reported in the Carlsberg ridge in the northern Indian Ocean, respectively. Interestingly, the two groups were observed to co-occur at the Onnuri vent field. This study suggests speciation of the brachyuran crabs of genus Austinograea in the Indian Ocean.1
Evaluation of Accuracy and Error Characteristics of Research Vessel Thermosalinograph Data Using Satellite-Based Sea Surface Temperature
No full text해수면온도(Sea Surface Temperature; SST)는 기상 및 기후변화와 대기-해양의 상호작용을 이해하기 위한 중요한 인자이다. 해수면온도 자료는 현장관측과 위성 기반 원격탐사를 통해 수집되며, 위성 기반 자료는 광역 모니터링이 가능하지만 환경적 요인으로 시공간적 공백이 발생한다. 자료 공백을 보완하기 위하여 정확도 높은 해수면온도 합성장 산출 연구가 진행 중이며, 충분한 현장관측자료 확보가 필수적이다. 한국해양과학기술원은 연안 및 대양을 대상으로 총 6척의 연구선을 운영 중이며, 표층 수온·염분측정기(Thermosalinograph, TSG)를 통해 운항 중 매 1분 간격의 수온자료를 생산하고 있다. 국외에서는 TSG 수온자료 기반의 해수면온도 자료의 검·보정 연구가 진행되고 있으나, 국내에서는 한국해양과학기술원(Korea Institute of Ocean Science and Technology, KIOST)에서 취득한 TSG 자료는 신뢰성 확보와 자료에 대한 정보 부족으로 인해 활용도가 저조한 실정이다. 본 연구에서는 TSG 수온자료를 활용한 해수면온도 합성장 자료 생산 가능성을 평가하기 위하여 위성기반 해수면온도 자료와 일치점을 생산하여 시계열 및 공간적 오차특성을 분석하였다. TSG 수온자료와 위성기반 해수면온도 자료간의 편차는 0.57°C로 일관성이 확인되었으며, 향후 TSG 수온자료를 활용한 해수면온도 합성장 자료의 품질 향상에 기여할 것으로 기대된다.22Nkc
Tracing floating Sargassum in the Yellow Sea and East China Sea using GOCI
No full textThe Yellow Sea (YS) and East China Sea (ECS) have the world’s largest supply of floating algae. The golden tides (Sargassum horneri) causes a huge socioeconomic problem in the vicinity of coastal areas. However, the annual pattern of the golden tide bloom is not well known due to changing air-sea interaction conditions. To understand the spatial and temporal variations, the multi-satellite data was used to detect the floating macroalgae which was determined by the Alternative Floating Algae Index and mapped over the study area using a 17-year data. The floating golden tide patches detected by both satellite data were overlapped to make the annual pattern maps.
The golden tides were generally found on spring in the YS and ECS. The Sargassum blooms was proceeded in the waters near the Yangtze River and Zhejiang Province, China and then floating into the east and northeast ward influenced by the Tsushima warm current or Kuroshio. The Sargassum blooms were build-up in the middle of the ECS and pile-up in the coast of Korea from March to May. Recently, the Sargassum blooms were temporally expanded from October to May from 2019 to 2023. We suggested two origins with tracing the temporal and spatial distribution and development. The first blooms were onset on fall around the Bohai Bay and/or Shandong Peninsula and southward controlled by the local wind and sea surface temperature condition on winter. The second blooms were initiated on winter near the Zhejiang Province, China and eastand northward affected by the local current and wind condition. Although the satellite (e.g. optical and ocean color sensor) have limited to monitor the golden tide blooms under the cloudy, severe weather conditions, small-scale blooms and coastal area, the satellite-detecting golden tide blooms shows promise in the terms of mapping blooms to understand the spatial and temporal distribution and development in regional scale of the YS and ECS.1
Ortholog Analysis and Transformation of Glycoside Hydrolase Genes in Hyperthermophilic Archaeal Thermococcus Species
No full textArchaea thrive in extreme environments, exhibiting unique traits with significant biotechnological potential. In this study, we investigated whether Thermococcus onnurineus NA1 could stably integrate a large glycoside hydrolase (GH) gene cluster from T. pacificus P-4, enhancing β-linked polysaccharides degradation for hydrogen production. Among 35 Thermococcus genomes examined via OrthoFinder2 and OrthoVenn3, and selecting Tpa-GH gene clusters as the target, we cloned and integrated Tpa-GH into T. onnurineus NA1 using a fosmid-based system, creating the GH03 mutant. Cultivation in a modified MM1 medium supplemented with laminarin revealed significantly higher growth and hydrogen production in T. onnurineus GH03 than in the wild-type strain. Our findings demonstrate the feasibility of stable, large-fragment DNA integration in hyperthermophilic archaea and underscore the promise of T. onnurineus GH03 as a strain for high-temperature biomass conversion.11Nsciescopu
Evolutionary insights into adaptation of hemocyanins from deep-sea hydrothermal vent shrimps
No full textDeep-sea hydrothermal vent shrimps inhabit environments with low oxygen levels and may even be exposed to hypoxic conditions. In response, their respiratory pigment, hemocyanin (Hc) may undergo molecular adaptations to enable them to survive in such extreme ecosystems. Therefore, we sampled four Alvinocarididae species from hydrothermal vents in the northern Central Indian Ridge and two types of Hc genes (α and γ) were observed. Employing the branch model, we detected positive selection for the deep-sea hydrothermal vent lineage, including 11 Decapoda species. Furthermore, using the branch-site model, we identified a putative mutant residue (Leu226, Ser377, and Ile390) close to the active site of Hc. Moreover, our results suggested potential molecular docking between two α-type Hc proteins. Thus, this study provides valuable and novel perspectives on the functional significance of the Hc gene in deep-sea hydrothermal vent shrimps, laying the foundation for future investigations in this intriguing area of research.11Nsciescopu
Mesoscale Flow Impacts on Downward Energy Flux of Near-Inertial Waves in the Kuroshio Extension
No full textIt is known that background mesoscale flows (BMFs) modify the local inertial frequency and affect the energy and vertical propagation speeds of near-inertial waves (NIWs), but their effects have not been quantified, especially using observations. This study aimed to quantify BMF effects on NIWs energy, group velocity, and the downward energy flux (F-z) of NIWs using 2 years of mooring data (November 2017-October 2019) from the Kuroshio Extension. By dividing the data into 11 days segments, the temporal variability of the effective near-inertial frequency and group velocity owing to the BMFs was considered. During winter, when NIWs are active-on a temporal average in anticyclonic flows-F-z increased by 50%, whereas in cyclonic flows, F-z decreased by 45% when the varying effective near-inertial frequency was considered. Because cyclonic circulations were twice as frequent, F-z decreased by similar to 17%, to 0.37 x 10(-3) W m(-2). Even so, this amount is similar to 1.8 times greater than that in the Northeastern Pacific and accounts for similar to 28% of the wind work rate, similar to eddy-resolving high-resolution numerical model results. This high efficiency suggests that NIWs could play a more important role in deep mixing than previously considered. To overcome spatiotemporal limitations of F-z estimation from our data, long-term eddy statistics were used to estimate overall F-z over the Kuroshio Extension. Anticyclonic circulations lasted longer, leading to an similar to 12% increase in F-z. Thus, the Kuroshio Extension is an important region for downward NIW energy propagation, and BMFs should be considered for accurate NIWs energetics.11Nsciescopu