An economic valuation and the sustainable development of a marine protected area: A case study of Cu Lao Cham, Vietnam: A thesis submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy at Lincoln University

The Vietnamese shoreline stretches for over 3,200 km with over 3,000 islands but the marine and coastal resources of Vietnam are under increasing threat from human activities. This includes Cu Lao Cham (Cham Island Marine Protected Area (CLC MPA)), which is recognised as an important area in terms of biodiversity and fish stocks in Vietnam. The important habitats in CLC MPA, such as coral reefs, seagrass beds, rocky shore, and sandy bottoms in the waters surrounding the CLC, have been seriously over-exploited. This exploitation is blamed as the main cause of the decline in marine resources. Conservation efforts have recently been implemented in the CLC MPA. However, economic analysis of the CLC MPA’s natural values has not yet investigated what may affect policy decisions on CLC MPA’s sustainable development. An economic valuation of the CLC MPA marine and coastal resources can provide a framework to sustainably manage the allocation and use of the resources. This study estimates the recreation and conservation values of marine resource in the CLC MPA using an onsite survey with a structured questionnaire. The Travel Cost Method was used to estimate the recreational values for respondents based on their visitation rate and their trips to the CLC MPA from 2013 to 2018. The results show that the respondents’ visitation rate and trips are significantly affected by their socio-economic characteristics (such as income, household size, gender, occupation and education), their transport means to travel between home and the CLC MPA, and other factors (travel and other expenses, time and purpose for visiting CLC MPA). Empirical evidence from Zonal Travel Cost Models (the OLS log-log form) suggests that the relationship between the respondents’ visitation rate and their travel cost is inelastic, which means that a change in the respondents’ travel costs nominally affects their visitation rate. The findings from the zero-truncated Poisson count models reveal that the aggregate recreational benefits in 2018 from the CLC MPA are estimated to be approximately VND950 billion (US$42.4 million). The consumer surplus is overestimated if multi-destination trips are omitted from the demand model, with approximately a 2.7The Contingent Valuation Method is used in this study to estimate the respondents’ willingness to pay (WTP) for the conservation of the CLC MPA (paying additional entrance fees). The results from Generalised Linear Models show that the WTP estimation varied among three different groups of respondents (combined, Vietnamese, and foreign visitors). Foreign respondents were willing to pay the highest amount and Vietnamese respondents pay the lowest amount (US$3.56 and US$1.99 per person per visit, respectively). On average, respondents visiting CLC MPA were willing to pay US$2.26 per person per visit

Higher chromatic rendition with Cr3+-doped yellow Y3Al5O12:Ce3+ for double-layer remote phosphor white-light-emitting diodes

Remote phosphor designs of white-light-emitting diodes (WLEDs) have been recognized for their high thermal stability and excellent luminous efficiency but not for the chromatic rendering. The study presents an approach for the remote phosphor structure to overcome the low-color-rendering issue by enriching its red-light spectral intensity through co-doping Cr3+ and Ce3+ ions into the yellow  Y3Al5O12 (YAG) phosphor compound. This ion co-doping process probably enhances emission spectra in the far-red range because of the energy transfer of the integrated ions: Ce3+ Cr3+. Additionally, the luminescence and color properties of the phosphor layer significantly depend on the doped concentration of the Cr3+ ion. Here, with 0.008% Cr3+ in the phosphor composite, either internal or external quantum performances of the dual-layer WLED light are enhanced, which achieved the number of 58.9% and 46.7%, respectively. The color rendering index (CRI) would also be higher if Cr3+ is added, about 77.9, compared to the CRI of 63.2 when using the original  YAG:Ce3+ phosphor layer

Sustainable management of a marine protected area in Vietnam: An application of visitors’ willingness to pay for conservation in Cu Lao Cham

As an important area in terms of biodiversity and fish stocks in Vietnam, Cu Lao Cham or Cham Islands (CLC) marine protected area (MPA) is under increasing threat from human activities. Conservation efforts have recently been implemented but economic analysis of the CLC MPA’s natural values did not investigate what may affect policy decisions on CLC MPA’s sustainable development. Using a structured questionnaire and a payment card technique (based on the contingent valuation method), we estimate visitors’ willingness to pay (WTP) for conservation of marine resources in the CLC MPA. The log-normal regression results indicate that the visitors’ WTP for conservation is affected by their characteristics, perceptions of environmental protection and conservation, and their assessment of the current CLC MPA entrance fee. Visitors are WTP an additional amount of US$2.26 per person for conservation while visiting the CLC MPA. This indicates that with the introduction of the proposed entrance fee (the mean WTP added to the current entrance fee), the CLC MPA management would not only have sufficient funds for their management and conservation programmes, but also that the number of visitors may decline slightly, which would reduce some of the pressure on the environment, natural resources, and coral reefs

Characteristics of Antibiotic-resistant E. coli Isolated from Perfume River in Hue City, Vietnam

Antibiotic resistant bacteria (ARB) in aquatic environments is attracting increasing attention. However, the spread of ARB along Perfume River in Hue City is poorly understood. This study aimed to phenotypically and genotypically characterize β-lactam- and fluoroquinolone-resistant Escherichia coli isolates from this river. Water samples were collected from the urban, rural, agricultural, and less-affected areas in March 2020. E. coli susceptibility to seven commonly employed antibiotics was analyzed using the disk diffusion method, and the antibiotic resistance genes (ARGs), qnrA, qnrB, qnrS, TEM, SHV, and CTX-M, were identified using polymerase chain reaction (PCR) and DNA sequencing. The antibiotic susceptibility patterns of E. coli revealed that the rate of amoxicillin resistance was the highest (60%). PCR assays and sequencing of 12 β-lactam-resistant E. coli isolates indicated the presence of blaTEM and blaCTX-M-15 in 58.3% and 16.7% of the isolates, respectively. Only one of four fluoroquinolon -resistant E. coli isolates harbored the qnrS, while qnrA or qnrB genes were not detected. These findings suggest that this water may be an essential source of transmissible ARGs in Hue City, which may have a detrimental impact on the people living in this area

Antioxidant, α-Amylase and α-Glucosidase Inhibitory Activities and Potential Constituents of <i>Canarium tramdenum</i> Bark

The fruits of Canarium tramdenum are commonly used as foods and cooking ingredients in Vietnam, Laos, and the southeast region of China, whilst the leaves are traditionally used for treating diarrhea and rheumatism. This study was conducted to investigate the potential use of this plant bark as antioxidants, and &#945;-amylase and &#945;-glucosidase inhibitors. Five different extracts of C. tramdenum bark (TDB) consisting of the extract (TDBS) and factional extracts hexane (TDBH), ethyl acetate (TDBE), butanol (TDBB), and water (TDBW) were evaluated. The TDBS extract contained the highest amount of total phenolic (112.14 mg gallic acid equivalent per g dry weight), while the TDBB extract had the most effective antioxidant capacity compared to other extracts. Its IC50 values were 12.33, 47.87, 33.25, and 103.74 &#181;g/mL in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2&#8242;-azino-bis (ABTS), reducing power (RP), and nitric oxide (NO) assays, respectively. Meanwhile, the lipid peroxidation inhibition of the four above extracts was proximate to that of butylated hydroxytoluene (BHT) as a standard antioxidant. The result of porcine pancreatic &#945;-amylase inhibition showed that TDB extracts have promising effects which are in line with the commercial diabetic inhibitor acarbose. Interestingly, the inhibitory ability on &#945;-glucosidase of all the extracts was higher than that of acarbose. Among the extracts, the TDBB extract expressed the strongest activity on the enzymatic reaction (IC50 = 18.93 &#181;g/mL) followed by the TDBW extract (IC50 = 25.27 &#181;g/mL), TDBS (IC50 = 28.17 &#181;g/mL), and TDBE extract (IC50 = 141.37 &#181;g/mL). The phytochemical constituents of the TDB extract were identified by gas chromatography&#8315;mass spectrometry (GC-MS). The principal constituents included nine phenolics, eight terpenoids, two steroids, and five compounds belonging to other chemical classes, which were the first reported in this plant. Among them, the presence of &#945;- and &#946;-amyrins were identified by GC-MS and appeared as the most dominant constituents in TDB extracts (1.52 mg/g). The results of this study revealed that C. tramdenum bark possessed rich phenolics and terpenoids, which might confer on reducing risks from diabetes. A high quantity of &#945;- and &#946;-amyrins highlighted the potentials of anti-inflammatory, anti-ulcer, anti-hyperlipidemic, anti-tumor, and hepatoprotective properties of C. tramdenum bark

Adaptive fisheries management in Vietnam: The use of indicators and the introduction of a multi-disciplinary Marine Fisheries Specialist Team to support implementation

Vietnam is in the process of introducing adaptive management based on indicators and time-series to manage its marine fisheries. The development of indicator-based frameworks for fisheries management has accelerated in recent years. This article describes the suite of indicators being suggested or used in Vietnam including the data-collection system. The Vietnamese approach is supported by an institutional structure consisting of a multi-disciplinary advisory system to facilitate the process of using indicators and to introduce knowledge-based management. The article concludes by identifying current problems and weaknesses and by providing suggestions for future improvement of the system.Adaptive fisheries management Multi-disciplinary advice Eco-system and fisheries profiles

Coastal Wetland Classification with Deep U-Net Convolutional Networks and Sentinel-2 Imagery: A Case Study at the Tien Yen Estuary of Vietnam

The natural wetland areas in Vietnam, which are transition areas from inland and ocean, play a crucial role in minimizing coastal hazards; however, during the last two decades, about 64% of these areas have been converted from the natural wetland to the human-made wetland. It is anticipated that the conversion rate continues to increase due to economic development and urbanization. Therefore, monitoring and assessment of the wetland are essential for the coastal vulnerability assessment and geo-ecosystem management. The aim of this study is to propose and verify a new deep learning approach to interpret 9 of 19 coastal wetland types classified in the RAMSAR and MONRE systems for the Tien Yen estuary of Vietnam. Herein, a Resnet framework was integrated into the U-Net to optimize the performance of the proposed deep learning model. The Sentinel-2, ALOS-DEM, and NOAA-DEM satellite images were used as the input data, whereas the output is the predefined nine wetland types. As a result, two ResU-Net models using Adam and RMSprop optimizer functions show the accuracy higher than 85%, especially in forested intertidal wetlands, aquaculture ponds, and farm ponds. The better performance of these models was proved, compared to Random Forest and Support Vector Machine methods. After optimizing the ResU-Net models, they were also used to map the coastal wetland areas correctly in the northeastern part of Vietnam. The final model can potentially update new wetland types in the southern parts and islands in Vietnam towards wetland change monitoring in real time

On the Degradation of Glyphosate by Photocatalysis Using TiO2/Biochar Composite Obtained from the Pyrolysis of Rice Husk

International audienceIn this study, titanium dioxide (TiO2) nanoparticles are immobilized onto rice husk biochar (RHB), as a porous support, for the photodegradation of glyphosate under UV light irradiation. The TiO2/RHB composites are prepared by pyrolysis and the sol-gel method. The SEM, XRD, EDX, and FT-IR results confirm the graphene structure of RHB and the formation of 10.61 nm TiO2 nanoparticles on the catalyst support. The effects of operating conditions, including catalyst dosage (3 g L−1, 5 g L−1, 10 g L−1, and 20 g L−1) and different illumination conditions (9 W lamp, 2 × 9 W lamps), on the removal of glyphosate from aqueous solutions were investigated. The photodegradation efficiency of 15 mg L−1 of commercial glyphosate was up to 99% after 5 h of irradiation at pH 3.0, with a TiO2/RHB dosage of 10 g L−1. However, the mineralization efficiency under this condition was lower than the decomposition efficiency of glyphosate, proving the partial degradation of glyphosate into AMPA and other metabolites after 5 h of reaction