Microplastics have become a global concern due to their persistent properties and impacts on the marine environment. This research investigates pollution sources and behaviors of microplastics at UNESCO Can Gio Mangrove Biosphere Reserve. Density flotation with sodium chloride is employed to extract microplastics from sand at Can Gio Beach, and a double‐filtration procedure is developed to recover microplastics from seawater at the beach and Dong Tranh Cape. The microplastics’ morphology and type are analyzed by micro‐Raman spectroscopy. The results show that microplastics are accumulated at concentrations from 31.99 to 92.56 MPs g⁻¹ at various sand layers. The seawater at Can Gio Beach and Dong Tranh Cape contains 6.44 and 3.75 MPs L⁻¹ of microplastics, respectively. White polyethylene fragments predominate, and all the microplastics comprise small secondary microplastics with a minimum size of 25 µm and a maximum size of 260 µm for fragments and a length of 640 µm for fibers. The proportions of polyethylene, polypropylene, polystyrene, and polymethylmethacrylate are similar. The differing percentages of other compositions in sand and seawater are attributed to the morphology and density of the microplastics. The results indicate the extent of microplastic pollution and suggest appropriate strategies for tourism development at the Biosphere Reserve.

Microplastics (MPs) are synthetic polymer pieces with a size of less than 5 mm that are ubiquitous in the marine environment. They have been recently detected in several wild species and sea products. An indispensable condiment in human food is marine salt that is produced from seawater. Since toxicity studies report potential health impacts when plastic debris is ingested, more attention must be paid to the MP contamination of sea salt and the underlying reasons for this. The central aim of this study is to evaluate the MPs contamination level of sea salt in correlation with the MPs contamination level of seawater in Vietnamese areas. Micro-Raman spectroscopy was employed to determine MPs in the samples collected from three artificial salt pans of Vietnam. The result revealed the presence of MPs in all study areas—Vung Tau (VT;14.54 MPs/L seawater and 114.67 MPs/kg salt), Ly Nhon (LN; 13.14 MPs/L seawater and 63.59 MPs/kg salt), and Can Thanh (9.42 MPs/L seawater and 93.69 MPs/kg salt). The comparisons highlight close correlations in the percentage, shape, size, and color of MPs, especially polyethylene, polyethylene terephthalate, and polypropylene particles extracted from the seawater and its salt. This study proved that seawater is a plastic pollution source for salts produced by traditional seawater evaporation. The study also alerts the prevalence of MPs in the environment and human consumables, thereby indicating that actions must be taken to reduce the pollution of water sources in Vung Tau and at the UNESCO Can Gio Mangrove Biosphere Reserve and improve salt production and refinery processes in order to minimize the number of MPs in final salt products for safe consumption.

Plastic pollution is one of the significant environmental concerns due to the threefold increase in global plastic waste. Marine microplastics, including petroleum-based plastic pieces and synthetic and artificial fibers smaller than 5 mm, are not only ubiquitous in natural water but also high in wastewater streams due to the direct discharge, transfer and breakdown of plastic items. This research aims to investigate the presence and dispersion of microplastics in the downtown area and coastal suburban area of Ho-Chi-Minh City by using Raman microscopy. As a result, the most common plastics (PE, PET, PA, PP, PVC, PS and PMMA) were detected, and most of them were fibrous shorter than 500 μm. The total microplastics decreased gradually from the urban waterborne (up to 220 MPs/L) via Can Gio UNESCO Mangrove Biosphere Reserve (10 MPs/L) and to the East Sea (3 MPs/L), which reveals the potential role of the mangrove in reducing marine contaminants including microplastics. This study provides important insights into microplastic pollution in the Western Pacific Region, especially the Saigon-Dong Nai river systems, supporting useful data for natural water resources management.

Vitexin and isovitexin are natural flavone C-glucosides that have numerous benefits for human health. However, their low oral bioavailability and poor gastrointestinal absorption dramatically restrict their potential medicinal uses. To overcome this challenge, chitosan-coated alginate microcapsules were prepared for intragastrical administration to rabbits. An LC-MS/MS method was developed and validated for the simultaneous determination of vitexin and isovitexin in the plasma of treated rabbits, using salicylic acid as the internal standard. Raw rabbit plasma samples were deproteinized using acetonitrile as a precipitation agent. Chromatographic separation was performed on a reversed-phase C18 column (100 mm × 4.6 mm, 3.5 µm), with an isocratic mobile solvent system comprising methanol and 0.1% acetic acid (40:60) as the mobile phase. All the analytes and the internal standard were ionized on a triple quadrupole mass spectrometer and electrospray ionization, operating in negative mode and multiple reaction monitoring. The analytical approach developed underwent validation in terms of system suitability, specificity, selectivity, LLOQ of 2 ng/mL, linearity (2.0–200 ng/mL, R² > 0.99), accuracy (the intra- and inter-day from 94 to 110% with the relative standard deviations no more than 8.7%, precision with the recoveries from 97% to 102%, matrix effect (90–100%), carry-over, dilution integrity (2 times), and stability at room and frozen temperature for up to 1 month, and all the parameters met FDA and EMA requirements for bioanalytical methods. The validated procedure was applied to measure the absorption of vitexin and isovitexin from encapsulated extracts in a pilot pharmacokinetic study on rabbit plasma. Compared to the raw traditional extracts, the microcapsules enhanced the bioavailability of vi-texin and isovitexin regarding C_max and AUC values.

Can Gio, designated in 2000, is the first Biosphere Reserve of Vietnam. In recent years, local agriculture, tourism, households, nearby industrial zones, and maritime transport have released substances into rivers flowing through Can Gio Mangrove to the East Sea and transported into creatures. This study aims to investigate microplastics and heavy metals in the famous seafood of Can Gio. A Raman microscope was used to identify microplastics from the tissue of oysters, grease snails, and clams after enzymatic treatment with trypsin. Heavy metals were quantified with ICP-MS after acidic treatment. As a result, microplastics were found in almost all samples, even up to 10 in a random individual of bivalve. Fibers dominated, especially from 30 to 150 µm long. The metal with the highest content was zinc, followed by copper, especially in oysters. Non-essential metals were also present in the soft tissue in the order As > Pb > Cd. The accumulation of metals in Can Gio’s molluscs was generally lower than in other regions and still in the allowed range for consumption of Vietnamese Standard. Although there have not been any Vietnamese regulations on the permissible level of microplastics for consumption, regular seafood intake will increase the risk of chronic poisoning and unknown disorders caused by the accumulation of microplastics and heavy metals.