Tất cả chứa ở đây http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/1 2026-08-07T10:14:31Z 2026-08-07T10:14:31Z Nguyen, Thanh Duong Vu, Duy Vinh Nguyen, Minh Hai http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21814 2026-08-07T04:16:06Z 2025-01-01T00:00:00Z

Title: Numerical simulation of seasonal currents in the Mekong Coastal Area: a case in 2019 Authors: Nguyen, Thanh Duong; Vu, Duy Vinh; Nguyen, Minh Hai Abstract: This study, employing the Delft3D numerical model, investigated the Mekong Delta’s seasonal current dynamics by simulating its hydrodynamic regime in 2019. Using Nash-Sutcliffe Efficiency and Root Mean Square Error metrics, the model’s accuracy in replicating measured water levels (cm) and currents at various stations was validated, achieving acceptable simulation results. This allowed for a reliable analysis of the delta’s current patterns. The study revealed that while the overall direction and peak velocity of current remain relatively consistent throughout the year, their spatial distribution undergoes significant shifts, particularly during the transitional periods between seasons. Monthly flow velocities reflect this seasonality, with strong (up to 1 m/s) and consistent northeast-southwest surface flows during the low flow season (minimal stratification), driven by northeasterly winds. Conversely, the flood season exhibits greater regional variability in velocity and direction due to strong freshwater input and fluctuating winds, with surface velocities reaching 1 m/s in the Mekong estuary in October but decreasing sharply with depth (strong stratification), and flow directions shifting dynamically throughout the season.

2025-01-01T00:00:00Z Lai, Duy Phuong Do, Manh Dung Luu, Xuan Hoa Nguyen, Xuan Thanh http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21813 2026-08-07T04:16:39Z 2025-01-01T00:00:00Z

Title: The reproductive biology of mangrove crab (Neosarmatium smithi) in Xuan Thuy National Park, Nam Dinh, Vietnam Authors: Lai, Duy Phuong; Do, Manh Dung; Luu, Xuan Hoa; Nguyen, Xuan Thanh Abstract: The results of the analysis of 458 samples of mangrove crab (Neosarmatium smithi) collected in areas where mangrove crab is distributed in the tidal zone with mangrove forests in Xuan Thuy Nam Dinh National Park from October 2022 to September 2023 showed that the spawning season of mangrove crab is from mid - April to early September, and is concentrated from early June to early August. In all months, the ratio of females to males is always dominant. The female/male ratio in the mangrove crab population averages 1.36 and ranges from 1.25–1.46. The onset of sexual maturity occurs when the carapace width (CW) of females exceeds 21 mm and that of males exceeds 24 mm. Absolute fecundity (Fa) ranged from 17,580–25,733 eggs/individual, averaging 21,571 eggs/individual. The larvae of the mangrove crab develop from zoea larvae with 5 sub - stages, and megalop larvae with 3 sub - stages. Our findings contribute information to the planning of the artificial seed production, conservation and sustainable development of the mangrove crab native resource.

2025-01-01T00:00:00Z Tran, Duc Thanh Dang, Hoai Nhon Bui, Van Vuong Duong, Thanh Nghi Nguyen, Dang Ngai Cao, Thi Thu Trang Vu, Duy Vinh http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21812 2026-08-07T04:16:58Z 2025-01-01T00:00:00Z

Title: Assessing the vulnerability of marine ecosystems in the Gulf of Tonkin to human impacts and climate change - natural disasters Authors: Tran, Duc Thanh; Dang, Hoai Nhon; Bui, Van Vuong; Duong, Thanh Nghi; Nguyen, Dang Ngai; Cao, Thi Thu Trang; Vu, Duy Vinh Abstract: The Gulf of Tonkin (Vietnam part) comprises 12 typical marine ecosystems distributed across 7 ecological regions. Human activities impacting the marine ecosystems are classified into three groups: strong impacts (fishing, aquaculture, navigation - ports, and marine infilling); medium impacts (dredging - dumping, mining, tourism - services); and weak impacts (security - defense). Climate change and natural disasters affecting marine ecosystems are categorized into three impact groups. The strong impact group includes water temperature, typhoons, waves, and rising sea levels. The medium impact group consists of turbidization, local freshening, salinization, and erosion. The low-impact group comprises circulation disturbances and sedimentation. The vulnerability of marine ecosystems, influenced by human activities, climate change, and natural disasters, varies and is classified into three levels. Highly vulnerable areas include lagoons, estuarine areas, tidal flats, seagrass beds, and coral reefs. The medium vulnerability encompasses ecosystems such as beaches, mangrove forests, and permanent wetlands. Low vulnerability encompasses ecosystems such as the seafloor, marine lakes, rocky coasts, and upwelling areas. Ecological zones with a high vulnerability levels include the coastal marine zones of Mong Cai - Do Son (Z.1) and Mui Roon - Hai Van (Z.4). The zones with medium vulnerability levels include the coastal marine zones of Do Son - Lach Truong (Z.2) and Lach Truong - Mui Roon (Z.3). In contrast zones with a low vulnerability levels include the northern marine zones of the Gulf (Z.5), the middle marine zone of the Gulf (Z.6), and the southern marine zone of the Gulf (Z.7).

2025-01-01T00:00:00Z Huỳnh, Hoàng Như Khánh Trương, Anh Khoa Nguyễn, Hoàng http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21811 2026-08-07T03:35:11Z 2025-01-01T00:00:00Z

Title: Phân bón lá Oligocarrageenan từ rong sụn – các tác động đến sinh trưởng và năng suất cây trồng Authors: Huỳnh, Hoàng Như Khánh; Trương, Anh Khoa; Nguyễn, Hoàng Abstract: This study presented the results of an investigation into the effects of carbohydrate concentrations in foliar fertilizer TN06-1 on the growth, performance, yield components, and overall productivity of maize and coffee plants. The biological compound - oligocarrageenan - used as a foliar fertilizer was derived from the hydrolysis of Kappaphycus alvarezii algae through an enzymatic process utilizing Viscozyme L in combination with ascorbic acid as an catalyst. Solutions containing oligocarrageenan (OCs) at varying concentrations demonstrated differential impacts on plant growth and yield parameters. Specifically, a concentration of 100 ppm yielded the most favorable results for plant height, ear kernel number, and yield in maize. Conversely, for coffee plants, optimal yield and seed quality were achieved with OCs concentrations of 150 or 200 ppm. Additionally, the findings indicated that the foliar fertilizer formulation containing oligocarrageenan exerted a direct positive influence on plant health and development, as evidenced by improved nutritional balance, enhanced root system development, and increased resilience to environmental stress, ultimately leading to higher crop quality.

2025-01-01T00:00:00Z Duong, Thanh Nghi Do, Thu Huong Pham, Quoc Hai Dinh, Hai Ngoc Nguyen, Dac Ve Nguyen, Thi Thu Ha Bui, Thi Mai Huyen Bui, Van Vuong Dang, Hoai Nhon Tran, Van Quy http://tvhdh.vnio.org.vn:8080/dspace/handle/123456789/21810 2026-08-07T03:33:05Z 2025-01-01T00:00:00Z

Title: Characteristics of Plastic Waste on Rivers in Hai Phong City, Vietnam Authors: Duong, Thanh Nghi; Do, Thu Huong; Pham, Quoc Hai; Dinh, Hai Ngoc; Nguyen, Dac Ve; Nguyen, Thi Thu Ha; Bui, Thi Mai Huyen; Bui, Van Vuong; Dang, Hoai Nhon; Tran, Van Quy Abstract: In this research, we conducted three complementary survey methods including visual observation, underwater sampling with nets, and riverside sampling with quantitative plots with six plastic waste monitoring stations on the river in Hai Phong city: An Thai, Tram Bac, Kien An, Bui Vien, Rao, Tan Vu Lach Huyen to study the plastic waste on rivers. We found the most concentrated plastic waste in the city was at Bui Vien station (1,239 objects 33.05%) and Rao station (938 objects, 25.05%). During the four months of monitoring plastic waste on the rivers in Hai Phong city (November, December of 2024 and June, August of 2025), the total amount of plastic waste collected was 3,749 objects. The amount of plastic waste in the dry season is higher than in the wet season, respectively 54.41% and 45.59%. In the nine groups of plastic waste monitored, nylon bags and packaging plastic bags account for the majority, at 24.03% and 35.48% respectively. Plastic waste with low proportion is beverage and food waste (6.68%), hygiene and sanitary waste (1.48%), fishing net and aquaculture waste (2.97%), miscellaneous items waste (8.13%), items of unidentifiable origin waste (13.44%), and other types of plastic waste (1.03%). The total amount of plastic waste will be highly concentrated in the dry season, accumulating in the urban center over the years and the number of types of plastic waste that need to be prioritized for treatment and management so that the urban can develop in the direction of a green, clean, smart, cultural and modern urban area.

2025-01-01T00:00:00Z