Preliminary results of the study on the reasons of the Hai Hau erosion phenomenon

Overall the evolution process of the Red River Delta based on the maps and historical data resulted in a fact that before the 20th century all the Nam Dinh coastline was attributed to accumulation. Then started the erosion process at Xuan Thuydistrict and from the period of 1935 - 1965 the most severe erosion was contributed in the stretch from Ha Lan to Hai Trieu, 1965 - 1990 in Hai Chinh - Hai Hoa, 1990 - 2005 in the middle part of Hai Chinh - Hai Thinh (Hai Hau district). The adjoining stretches were suffered from not severe erosion. At the same time, the Ba Lat mouth is advanced to the sea and to the North and South direction by the time with a very high rate.The first task of the mathematical modeling of coastal line evolution of Hai Hau is to evaluate this important historical marked periods e. g. to model the coastal line at the periods before 1900, 1935 - 1965; 1965 - 1990; 1990 - 2005. The tasks is very complicated and time and working labors consuming.In the paper, the primarily results of the above mentioned simulations (as waves, currents, sediments transports and bottom - coastal lines evolution) has been shown. Based on the obtained results, there is a strong correlation between the protrusion magnitude and the southward moving of the erosion areas

Some study results of Cam Ranh - Binh Thuan mud eruption strip

Most of the mud eruption locations are distributed in a stretching strip, running in NE-SW direction from Cam Ranh - Ninh Thuan - Binh Thuan NE-SW tectonic fault zone and coinciding with a tectonically crushed zone. The erupted mud consists of sand, mud, clay. The clay contains alkaline montmorillonite, formed following chemical weathering and re-sedimentation processes from rocks containing alkaline minerals in a semi-arid climate area, located in a low terrain or a tectonic subsiding zone with a large fluctuation in groundwater level. The mud eruption  has a close relation to factors (of) climate, topography, geomorphology, hydrogeology, petrography and tectonic activities in the area. Among these, tectonic factors are the most important for they create not only soil and rock crushed zone, paving favorable conditions for strong weathering process at depth, but also to form canals to bring hot groundwater and minerals from certain depths upward, and by the effects of pressurized groundwater and partly due to the expansion in volume of bentonite clay pushing the muddy clay material through the tectonic cracks to the surface of the current terrain. The mud eruption process is not deep; but it may occur from a shallow level, about 4-18 m below, under the impact of the above elements.ReferencesCao Dinh Trieu, 2006. Characteristics of Earthquake Activities of Central Southern and Southern Sea.  Journal of Geology, Range A, 293(3-4), Hanoi.   Cao Dinh Trieu, et al., 2013. Modern geodynamics in Vietnamese territory. Natural Sciences and Technology Publishing House, Hanoi, 242.Ho Vuong Binh, et al., 1990. Research report on evaluation of prospects and possibility of using alkaline bentonite at Thuan Hai. Archived at the Center for Information Archives of Geology, Hanoi.Le Duc An, 1990. Geomorphological and neotectonic features of Thuan Hai area. Geological Science and Technique Information, (1-2), 5-25, Hanoi.Le Duy Bach, et al., 2007. Tectonic features Pliocene - Quaternary at Southeast continental shelf of Vietnam. Journal of Sciences of the Earth, 29(3), 218-227, Hanoi.Mazzini. A, A. Nermoen, M. Krotkiewski, Y. Podladchikov, S. Planke, H. Svensen, 2009. Strike-slip faulting as a trigger mechanism for overpressure release through piercement structures. Implications for the Lusi mud eruption, Indonesia. Marine and Petroleum Geology, doi:10.1016/j.marpetgeo.2009.03.001Medialdea. T, et al., 2003. Tectonics and mud eruption  development in the Gulf of Cadiz.  Marine Geology, 261(1-4), 48-63.Nguyen Duc Thai, et al., 2011. Report on survey results of land crack and mud appearance locations at Suoi Da village, Loi Hai commune, Thuan Bac district, Ninh Thuan province. Archived at Division for Water Resources Planning and Investigation for the Central Region of Vietnam.Nguyen Duc Thang (chief author) et al., 1988. Report on surveying and mapping of Geology and Minerals in Phan Rang-Nha Trang area at 1:200,000 scale. Archived at the Center for Information Archives of Geology, Hanoi.Nguyen Hong Phuong, 2004. Map of earthquake dangerous rate in Vietnam and the East Sea. Journal of Sciences of the Earth,  26(2), 97-111, Hanoi.Pham Van An, et al., 1990. Features of weathering crust at dry hot area Thuan Hai and origin of alkaline bentonite clay. Geological Science and Technique Information, (1-2), 72-79, Hanoi.Pham Van Hung, 2000. Determining kinematic properties of cracks by analyzing tectonic cracks in the South Central region, Journal of Sciences of the Earth, 29(2), 113-119, (in Vietnamese).Pham Van Hung, 2001. Quaternary - modern operational features of tectonic fault at the East edge of Kon Tum massif. Journal of Geology, 267, 43-49, Hanoi.Pham Van Nam, et al., 1988. Report on hydrogeological-engineering geological Mapping at 1:200,000 scale in Phan Rang-Nha Trang region. Archived at Division for Water Resources Planning and Investigation for the Central Region of Vietnam, Nha Trang.Phan Trong Trinh, 2012. Recent tectonics and modern geodynamics in Vietnam’s Sea and adjacent zones. Natural Sciences and Technology Publishing House, Hanoi, 331p.Pham Van Thuc, et al., 2004. Seismic zoning of the East Sea and coastal area in Vietnam. Journal of Geology, Range A, 285(11-12), Hanoi.Phung Van Phach, et al., 1996. Some research results of gases ash eruption phenomenon at Pleiku Highland in 1993. Geological Resources, 1, Science and Technique Publishing House, 396-405.Quo-Cheng Sung, Hung-Cheng Chang, HSing-Chang Liu, Yen-Chieh Chen, 2010. Mud eruption along the chihan fault in Southwestern Taiwan Arelease bend model. Geomorphology, 118, 188-198.Tran Van Thang, et al., 2006. Tectonic development characteristics of Da Lat zone and adjacent zone in late Mezozoi-Kainozoi. Journal of Sciences of the Earth, 28(2), 140-149, (in Vietnamese)..Stepanek P., Ho Trong Ty, 1986. Report on mineral geological mapping at Phan Rang-Cam Ranh at 1:50,000 scale. Archived at the Center for Information Archives of Geology, Hanoi.Vo Cong Nghiep, et al., 1998. List of hot water and minerals resources in Vietnam. Ministry of Industry, General Department of Geology and Minerals of Vietnam, Hanoi. 308p.Uong Dinh Khanh, 2004. Geomorphological characteristics of the hilly areas Ninh Thuan - Binh Thuan. Doctorate thesis, archived at National Library, Hanoi.Yin. P, S. Bern, P. Vagner, B. Loubrieu, Z. Liu, 2003. Mud eruption at the shelf margin of the East China Sea. Marine Geology, 194(3-4), 135-149.http://www.mhc.vn/. Minh Ha Bentonite Minerals JSC. 

The impact of corporate social responsibility and risk management on financial performance: The case of Vietnamese textile firm

The objective of this study is to assess the impact of corporate social responsibility (CSR) and risk management (RM) on financial performance (FP), and evaluate the moderate role of firm size in the relationship between risk management and financial performance. The study was conducted on a re-search sample of 389 Vietnamese textile firms. The results show that corporate social responsibility (CSR) was an optimal measure to minimize risks and improves financial performance. The good CSR policy reduces corporate risk and improves financial performance. Other way, the bad CSR policy increases corporate risk and impacts negatively on financial performance. In addition, the moderate role of firm size in the relationship between risk management and financial performance is statistically significant

Current advances in seagrass research: A review from Viet Nam

Seagrass meadows provide valuable ecosystem services but are fragile and threatened ecosystems all over the world. This review highlights the current advances in seagrass research from Viet Nam. One goal is to support decision makers in developing science-based conservation strategies. In recent years, several techniques were applied to estimate the size of seagrass meadows. Independent from the method used, there is an alarming decline in the seagrass area in almost all parts of Viet Nam. Since 1990, a decline of 46.5% or 13,549 ha was found. Only in a few protected and difficult-to-reach areas was an increase observed. Conditions at those sites could be investigated in more detail to make suggestions for conservation and recovery of seagrass meadows. Due to their lifestyle and morphology, seagrasses take up compounds from their environment easily. Phytoremediation processes of Thalassia hemprichii and Enhalus acoroides are described exemplarily. High accumulation of heavy metals dependent on their concentration in the environment in different organs can be observed. On the one hand, seagrasses play a role in phytoremediation processes in polluted areas; on the other hand, they might suffer at high concentrations, and pollution will contribute to their overall decline. Compared with the neighboring countries, the total Corg stock from seagrass beds in Viet Nam was much lower than in the Philippines and Indonesia but higher than that of Malaysia and Myanmar. Due to an exceptionally long latitudinal coastline of 3,260 km covering cool to warm water environments, the seagrass species composition in Viet Nam shows a high diversity and a high plasticity within species boundaries. This leads to challenges in taxonomic issues, especially with the Halophila genus, which can be better deduced from genetic diversity/population structures of members of Hydrocharitaceae. Finally, the current seagrass conservation and management efforts in Viet Nam are presented and discussed. Only decisions based on the interdisciplinary cooperation of scientists from all disciplines mentioned will finally lead to conserve this valuable ecosystem for mankind and biodiversity

Assessment of aflatoxin B1 contamination in rice and maize

Introduction: Aflatoxins B1 are among the most common poisonous mycotoxins produced by certain fungi that harm animals and crops. Mycotoxins can cause a variety of adverse health effects and pose a serious health threat to humans. The Maximum Residue Limits of aflatoxin B1 in processed cereals and ingredients are 2 parts per billion (ppb) and 5 ppb, respectively. Objectives: To evaluate the status of aflatoxin B 1 contamination in rice, corn and staple food produced in Ha Giang province compared with the maximum permitted levels. Methods: A total of 210 rice and maize samples were analyzed to quantify the level of aflatoxin B1. Analysis of mycotoxins was conducted by High Performance Liquid Chromatography using a fluorescence detector. Results: It was found that rice, rice products, maize, and maize products had a mean aflatoxin B1 content of 1.79 ppb, 2.55 ppb, 2.19 ppb, and 6.35 ppb, respectively. The results also showed that 71.9% of samples were contaminated with mycotoxins, and 14.28% of samples exceeded the maximum allowable limit. Conclusion: The concentration of aflatoxin B1 in 14.28% of the samples are over permissible limits by nationwide regulations

The impact of environmental and climatic variation on the spatiotemporal trends of hospitalized pediatric diarrhea in Ho Chi Minh City, Vietnam.

It is predicted that the integration of climate-based early warning systems into existing action plans will facilitate the timely provision of interventions to diarrheal disease epidemics in resource-poor settings. Diarrhea remains a considerable public health problem in Ho Chi Minh City (HCMC), Vietnam and we aimed to quantify variation in the impact of environmental conditions on diarrheal disease risk across the city. Using all inpatient diarrheal admissions data from three large hospitals within HCMC, we developed a mixed effects regression model to differentiate district-level variation in risk due to environmental conditions from the overarching seasonality of diarrheal disease hospitalization in HCMC. We identified considerable spatial heterogeneity in the risk of all-cause diarrhea across districts of HCMC with low elevation and differential responses to flooding, air temperature, and humidity driving further spatial heterogeneity in diarrheal disease risk. The incorporation of these results into predictive forecasting algorithms will provide a powerful resource to aid diarrheal disease prevention and control practices in HCMC and other similar settings

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions