Macroplastic and microplastic contamination assessment of a tropical river (Saigon River, Vietnam) transversed by a developing megacity.

https://hal.archives-ouvertes.fr/hal-02297526/document

Nutrient dynamics and eutrophication assessment in the tropical river system of Saigon - Dongnai (southern Vietnam).

Improved rice residue burning emissions estimates: Accounting for practice-specific emission factors in air pollution assessments of Vietnam.

https://hal.archives-ouvertes.fr/hal-02356823/document

Trace metals partitioning between particulate and dissolved phases along a tropical mangrove estuary (Can Gio, Vietnam).

In this study, we estimate rice residue, associated burning emissions, and compare results with existing emissions inventories employing a bottom-up approach We first estimated field-level post-harvest rice residues, including separate fuel-loading factors for rice straw and rice stubble Results suggested fuel-loading factors of 027 kg m-2 (±0033), 061 kg m-2 (±0076), and 088 kg m-2 (±0083) for rice straw, stubble, and total post-harvest biomass, respectively Using these factors, we quantified potential emissions from rice residue burning and compared our estimates with other studies Our results suggest total rice residue burning emissions as 224 Gg PM25, 3654 Gg CO and 56779 Gg CO2 for Hanoi Province, which are significantly higher than earlier studies We attribute our higher emission estimates to improved fuel-loading factors; moreover, we infer that some earlier studies relying on residue-to-product ratios could be underestimating rice residue emissions by more than a factor of 23 for Hanoi, Vietnam Using the rice planted area data from the Vietnamese government, and combining our fuel-loading factors, we also estimated rice residue PM25 emissions for the entirety of Vietnam and compared these estimates with an existing all-sources emissions inventory, and the Global Fire Emissions Database (GFED) Results suggest 7598 Gg of PM25 released from rice residue burning accounting for 128% of total emissions for Vietnam The GFED database suggests 4256 Gg PM25 from biomass burning with 562 Gg attributed to agricultural waste burning indicating satellite-based methods may be significantly underestimating emissions Our results not only provide improved residue and emission estimates, but also highlight the need for emissions mitigation from rice residue burning

https://iopscience.iop.org/article/10.1088/1748-9326/aa751d/pdf

Satellites may underestimate rice residue and associated burning emissions in Vietnam.

The Saigon River, Southern Vietnam, crosses one of the most dynamic developing Megacity in Southeast Asia: Ho Chi Minh City (HCMC). The increased economic, industrial, and domestic developments may affect the environmental quality of water and halieutic resources. In this study, we evaluated the seasonal (dry and wet seasons) biogeochemical state of the Saigon River during two snapshot campaigns conducted along the river basin upstream from HCMC; the Saigon River was characterized by slightly acidic (pH 5.7–7.7) and oxygen-depleted water (dissolved oxygen (DO), 0.36–5.18 mg l−1). Nutrients (N–NH4 = 0.01–2.41, N–NO3 = 0.14–2.72, and P–PO4 = ~0–0.42 mg l−1), DOC (2.2–8.0 mg l−1), POC, and trace metal(oid) (As, Cd, Cr, Cu, Zn, and Hg) concentrations were low showing a good quality of the upstream river. In the urban center area, DO dropped to 0.03 mg l−1 accompanied with a rise of nutrient concentrations (e.g., N–NH4, up to 17.7 mg l−1) likely originating from wastewater discharges. Trace metal concentrations also rose sharply (e.g., Cr and Hg rose up to 10-fold higher) in both water and sediments but remained under the World Health Organization (WHO) and Vietnamese concentration guidelines. In the downstream estuarine area, the intrusion of marine waters diluted water flowing from HCMC, leading water quality to return close to the state observed upstream from HCMC. In general, levels of nutrient and metal contaminations along the Saigon River during both seasons appear moderate regarding to Vietnamese and WHO guidelines although the urban area is highlighted as the major contributor for metal(oid) emissions. Finally, we showed that apart from wastewater and industrial discharges that affect the river quality, metal(oid) partitioning between solid and solution is controlled by the change in water geochemistry along the continuum during both seasons, such as DO (e.g., for As and Cr) and pH (e.g., for Pb) which drives their sorption/dissolution dynamics.

https://hal.archives-ouvertes.fr/hal-02357360/document

Baseline seasonal investigation of nutrients and trace metals in surface waters and sediments along the Saigon River basin impacted by the megacity of Ho Chi Minh (Vietnam)

***東京大学生産技術研究所 Institute of Industrial Science, The University of Tokyo キーワード:ベトナム,地域診断,バイオガスダイジェスター,家畜ふん尿,稲作,環境影響 ベトナム南部都市近郊農村におけるバイオマス利用に関する地域診断 Regional Diagnosis of Biomass Use in a Suburban Village of Southern Vietnam ○折立文子*・柚山義人*・中村真人*・山岡 賢* Nguyen Phuoc Dan**・Dang Vu Bich Hanh**・迫田章義***・望月和博*** ORITATE Fumiko, YUYAMA Yoshito, NAKAMURA Masato, YAMAOKA Masaru, Nguyen Phuoc Dan, Dang Vu Bich Hanh, SAKODA Akiyoshi and MOCHIDZUKI Kazuhiro

Regional Diagnosis of Biomass Use in Suburban Village in Southern Vietnam

In this study, we successfully crosslinked chitosan using STPP and produced chitosan beads to adsorb copper ions and subsequently phosphate ions from aqueous solutions. The optimal concentrations of chitosan (2% w/v) and STPP (7.5% w/v) during chitosan beads preparation and the optimal pH of 5.0 during adsorption were determined. Several adsorption models, including pseudo-first-order, pseudo-second-order, Langmuir, and Freundlich models, were used to evaluate the static adsorption experimental data. Moreover, the chitosan beads were applied in a dynamic adsorption column and several models including Bohart-Adam, Thomas, Yoon-Nelson, and Clark models were used to describe the system. This study showed that after adsorbing heavy metal ions, chitosan-STPP beads can be used for further adsorption of toxic anions from wastewater.

/pdf/sequent-adsorption-of-phosphate-ions-by-copper-ions-adsorbed-2o4gmy3a.pdf

Sequent Adsorption of phosphate ions by Copper ions Adsorbed on Tripolyphosphate Chitosan

Depending on different applications or materials that integrate with the substrate as well as the transduction method used in the biosensors, different materials of the substrate are considered. This research focuses on selecting the appropriate substrate in designing biosensors, detecting microorganisms in the environment. In this study, the glass slide (glass), Polyethylen plastic (PE plastic), and the cellulose paper (cellulose acetate (CA) & cellulose nitrate (CN)) are investigated substrates for coating AgNPs/ZIF-8 – material used as an optical signal amplification in further steps, using structural analysis techniques – Scanning Electron Microscopy (SEM) for morphology characterization and the Energy Dispersive Spectrometer (EDS) for optical characterization. A morphology characterization with SEM showed that cellulose paper is a better substrate in comparing with the other substrates (glass, PE), because the sensity of distribution on CN was the highest (85-90%) when it coated with AgNPs/ZIF-8. According to EDS analysis, the ratios of Ag in mixture on CN substrate (15.38±0.39% mass) is slightly higher than CA substrate (13.58±0.39% mass); and about 53 times higher than glass substrate (0.37±0.13% mass) and PE plastic substrate (0.29±0.08%). Therefore, cellulose paper (CA) will be suggested to select for further research as a new material with cost (inexpensive) and effectiveness in coating AgNPs/ZIF-8.

/pdf/determination-of-the-efficiency-of-agnps-zif-8-coating-on-uyrn9yvd.pdf

Vu Bich Hanh Dang

Papers

Baseline seasonal investigation of nutrients and trace metals in surface waters and sediments along the Saigon River basin impacted by the megacity of Ho Chi Minh (Vietnam)

Regional Diagnosis of Biomass Use in Suburban Village in Southern Vietnam

Sequent Adsorption of phosphate ions by Copper ions Adsorbed on Tripolyphosphate Chitosan

Determination of the efficiency of AgNPs/ZIF-8 coating on different substrates