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Biochar from crop residues plays an important role in reclamation of degraded rice soil due to imbalance fertilizer application and soil carbon sequestration. The objective of this study aimed to evaluate the best type and rate of biochar application for rice dry matter and soil organic carbon improvement. Therefore, pot experiments were carried out in two seasons of spring and summer 2023 at the University of Agriculture and Forestry, Hue University. Twelve treatments including 2 types of biochar (rice husk and peanut shell) and 6 application rates (0, 1, 2, 3, 4, 5%) were used and arranged in a randomized block design with three replications. Research results showed that the shoot dry matter was higher 9.5-27.0% (spring season) and 19.1-26.9% (summer season) at a rate of 5% application in both types of biochar than control. Rice husk biochar application had higher shoot dry matter than peanut shell biochar application in the same application rate from 0.30-0.46 g/plant in both seasons. Similarly, organic carbon was found the highest content (2.15-2.21%) when the application of biochar from crop residues at a rate of 5%. Biochar from crop residues is considered as a good amendment for increasing crop dry matter and soil organic carbon. [ABSTRACT FROM AUTHOR]

One way to effectively use rice straw without causing environmental pollution is to produce biochar and reuse it to improve rice yield and soil properties. Using rice straw biochar has increased rice productivity and can reduce chemical fertilizers. Therefore, this study aimed to evaluate the effects of rice straw biochar application with reduced chemical fertilizer on the growth and yield of rice at Quang Phu commune, Quang Dien district, Thua Thien Hue province, Vietnam with four treatments of the coapplication of rice straw biochar doses of 5, 7.5 and 10 t/ha and chemical fertilizers of 75, 50 and 25% of the recommended dose. Growth parameters, yield components, yield of rice, and soil property were investigated. The results showed that the rice straw biochar had a positive effect on the growth, yield of rice, and soil properties. The coapplication of rice straw biochar of the level of 10 t/ha and chemical fertilizer of 25% of the recommended dose was optimal levels produced the highest growth and yield (63 t/ ha). The co-application of rice straw biochar and chemical fertilizers increased organic matter, improved both soil physical and chemical properties, and reduced chemical fertilizer use. As a result, the rice straw biochar may be recommended to farmers to apply for rice production. [ABSTRACT FROM AUTHOR]

Intensive rice cultivation for a long time resulted in increasing soil degradation and less yield. This study aimed to evaluate effects of the combining reducing nitrogen fertilizer (N) with biochar amendment on soil chemical properties, rice growth parameters, and grain yield in the rice cultivation system in the Mekong Delta region, Vietnam (VMD). Field experiment was designed in the split-plot design with two factors, including N fertilizer (main plot) and biochar (sub-plot). Two N fertilizer rates were: (N50)—50 kg N ha–1 and (N100)—100 kg N ha–1, which is the farmer's practice. Biochar was amended with three rates: no applied biochar (B0), 5 t ha–1 (B5), and 10 t ha–1 (B10). The results indicated that reducing N fertilizer by 50% combined 5–10 t biochar ha–1 resulted in maintaining soil pH, soil electrical conductivity, soil organic carbon, cation exchange capacity, and rice biomass. Applying biochar at a rate of 5–10 t ha–1 significantly increased the available N, available P, and rice height compared to the treatment with no applied biochar (B0). Rice yield in the treatments applied with 5–10 t ha–1 was significantly higher than the treatment without the use of biochar by 11.6–14.7%. The findings of this study confirmed that reducing 50% N fertilizer combined with 5 t ha–1 or 10 t ha–1 of biochar could improve soil available N, available P, rice growth, and grain yield in intensive rice cultivation systems in the VMD region. [ABSTRACT FROM AUTHOR]

Heavy metal contamination in agricultural land is an alarming issue in Vietnam. It is necessary to develop suitable remediation methods for environmental and farming purposes. The present study investigated the effectiveness of using peanut shell-derived biochar to remediate the two heavy metals Zn and Pb in laboratory soil assays following Tessier's sequential extraction procedure. The concentration of heavy metals was analyzed using Inductively coupled plasma mass spectrometry (ICP-MS). This study also compared the effectiveness of the blend of biochar and apatite applied and the mere biochar amendment on the chemical fractions of Pb and Zn in the contaminated agricultural soil. Results have shown that the investigated soil was extremely polluted by Pb (3047.8 mg kg−1) and Zn (2034.3 mg kg−1). In addition, the pH, organic carbon, and electrical conductivity values of amended soil samples increased with the increase in the amendment's ratios. The distribution of heavy metals in soil samples was in the descending order of carbonate fraction (F2) > residue fraction (F5) > exchangeable fraction (F1) > Fe/Mn oxide fraction (F3) > organic fraction (F4) for Pb and F5   ≈   F2 > F1 > F3 > F4 for Zn. The peanut shell-derived biochar produced at 400 °C and 600 °C amended at a 10% ratio (PB4:10 and PB6:10) could significantly reduce the exchangeable fraction Zn from 424.82 mg kg−1 to 277.69 mg kg−1 and 302.89 mg kg−1, respectively, and Pb from 495.77 mg kg−1 to 234.55 mg kg−1 and 275.15 mg kg−1, respectively, and immobilize them in soil. Amending the biochar and apatite combination increased the soil pH, then produced a highly negative charge on the soil surface and facilitated Pb and Zn adsorption. This study shows that the amendment of biochar and biochar blended with apatite could stabilize Pb and Zn fractions, indicating the potential of these amendments to remediate Pb and Zn in contaminated soil. [ABSTRACT FROM AUTHOR]

Given that rice husk biochar has been shown to modulate salinity in salt-affected acid soils, the objective of this study was to investigate the effects of organic amendment of salinized acid soils on P fractions, enzyme activities, and associated rice yield. Four treatments, viz. Rice–Rice–Rice, [RRR]; Fallow–Rice–Rice, [FRR]; Fallow–Rice–Rice + 3 Mg ha−1 of compost [FRR + Comp]; and Fallow–Rice–Rice + 10 Mg ha−1 of biochar [FRR + BC] were established at Ben Tre and Kien Giang sites, Viet Nam, over six consecutive crops. Soil properties at harvest of the sixth crop showed that there were diverse patterns of fractionation between P forms with respect to treatment. Overarchingly, biochar increased labile and moderately labile inorganic P and organic P by 30% to 70%, respectively, whilst compost had a relatively modest effect on these pools. Soil phosphatase activities at crop tillering increased following the FRR + Comp and FRR + BC treatments compared with those in RRR, except for acid phosphatase at Ben Tre. At harvest, there were no significant differences between the enzyme activities among the treatments. Rice yield was positively correlated with the more labile forms of P, soil C, and acid phosphatase activity. In the absence of organic amendments, there was no effect of triple versus double rice crops being grown in one-year cycle. Repeated application of biochar (10 Mg ha−1 × 5 times) showed potential to increase grain yields and total soil C in salt-affected acid soils, via modulation of P transformations to more plant-available forms. [ABSTRACT FROM AUTHOR]

This study aimed to optimize the recovery of ammonium and phosphate from wastewater using Mg-modified biochar as an adsorbent. Given the situation of domestic wastewater and agricultural waste in Vietnam, the researchers fabricated biochar from rice husk and modified it with magnesium salt to make it an effective material for wastewater treatment. To determine the optimal conditions for the experiments, the response surface methodology was used, specifically the central composite design (CCD) model with four factors, namely biochar dosage (g/L), pH, N:P ratio, and initial concentrations of NH4+ and PO43- . The material was thoroughly characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) to ensure that it met the desired specifications. Based on the experimental design, the optimal conditions were determined to be a biochar dosage of 0.12 g/L, an N:P ratio of 1.25, an initial concentration of 60 mg/L, and a pH of 6. Tests conducted in synthetic wastewater produced results that were in agreement with the predicted values. However, when the optimized values were tested in domestic wastewater, only phosphate removal showed good agreement with an efficiency of 93% compared to the predicted optimization value of 88%. This study demonstrates the potential of Mg-modified biochar as an effective adsorbent for recovering ammonium and phosphate from wastewater. Although further optimization may be required for ammonium removal in domestic wastewater, the results are promising and warrant further investigation. [ABSTRACT FROM AUTHOR]

Cropping of acid sulfate soils requires effective treatment of their inherently low pH. We evaluated the efficacy of applications of two levels of lime (0 or 2 Mg/ha), two levels of organic fertiliser (0 or 5 Mg/ha), and three levels of biochar (0, 10 or 30 Mg/ha) in a factorial design for ameliorating acidity in an acid sulfate soil, and measured the subsequent growth and yield of baby corn (Zea mays L.). Lime increased soil pH(H2O) from 3.75 to 4.12, salinity from 1.72 to 1.95 dS/m, and cob yield by 30%. None of the amendments significantly altered total organic carbon or total nitrogen concentrations in the soil. Biochar additions increased cob yields by an average of 28% on both unlimed and limed soil. Addition of organic fertiliser increased cob yield by 45% on unlimed soil but had no significant effect on yields on limed soil. The yields obtained with liming were similar to the highest yields achieved with biochar or organic fertiliser applied either separately or in combinations. Overall, cob yields were increased by 19% with addition of organic fertiliser. The yield increseas from additions of biochar or organic fertiliser were associated with improvements in nutrient supply. However, the increases in cob yield were associated with reduced cob protein, probably resulting from poor availability of nitrogen late in the season. We conclude that biochar and organic fertiliser applied in relatively large quantities can be viable treatments for cropping acid sulfate soils. Biochar and organic fertiliser when applied in relatively large quantities can be as effective as liming for cropping acid sulfate soils. The three amendments added separately or in any combination increased growth and yield of baby corn but impaired cob protein content. [ABSTRACT FROM AUTHOR]

Access to clean water is still limited in a number of regions, especially country sides, rural, and mountainous areas in Vietnam. Therefore, studies on clean water production by using sustainable and affordable processes for locals to access to clean water are of great importance. In this research, we produced laterite-based adsorbents by thermal treatment of natural laterite. The produced adsorbents were characterized in terms of morphology, crystallite, chemical composition, surface functional groups, surface charges, and surface area. The adsorption processes of Ni2+ and Cu2+ onto thermally treated laterite were studied. The treated laterite was also deployed to the removal of pollutants from real rain water. Finally, treated laterite was used in a combination system to purify rain water to produce drinking water for households in Hai Dong commune, Hai Hau district, Nam Dinh province. The results showed that the adsorption of Ni2+ and Cu2+ by thermally treated laterite reached equilibrium after 40 min and followed the Langmuir sorption isotherm, with the maximum uptake of 27.6 mg/g for Cu2+ and 17.4 mg/g for Ni2+. The second-order-kinetic model described the best the adsorption of Cu2+ and Ni2+ from aqueous solution, implying chemisorption was predominant mechanism. The treated laterite was suitable for heavy metal removal but less effective for the removal of anions from water. The combination of solar heating system with treated laterite, sand, and activated carbon allowed to safely produce drinking water from rain water, which presented the water quality respecting the Vietnam national standard for drinking water (QCVN 01:09/BYT). [ABSTRACT FROM AUTHOR]

In this study, porous biochar (PBC) was prepared by acid activation of biochar derived from food waste (FWBC) and used as a suitable approach for the removal of 4-chlorophenol (CP) in wastewater. The characterization of PBC and the influent of different experimental conditions are determined. After the acid activation process, the surface area, porosity, and functional groups of PBC were developed. The removal performances of CP (1 mg/L) by PBC and FWBC were archived at 97.8 and 82.1%, respectively. Adsorption kinetics and isotherms of CP were followed by the second-order and Langmuir models, respectively. The maximum capacities of CP uptake onto mono-layer of FWBC and PBC based on the Langmuir model were determined at 79.8 and 108.7 mg/g, respectively. Besides, PBC could remove more than 89% CP from wastewater within 45 min of reaction time and it is suitable to reuse 8 times with over 60% adsorption efficiency of CP. In addition, the adsorption mechanism and environmental impact were discussed in detail. This work could bring a sustainable approach to the treatment of CP in wastewater as well as the management of food waste in Vietnam. [ABSTRACT FROM AUTHOR]

In this work, alginate-modified biochar derived from rice husk waste was synthesized using a simple process. The modified biochar (MBC) and rice husk biochar (RhBC) were investigated for removing Pb (II) ions in wastewater. The BET result displayed significantly improved specific surface area of MBC up to 120 m2/g along with a total pore volume of 0.653 cm3/g. FTIR spectrums presented the higher oxygen-contained functional groups of MBC as compared to RhBC, resulting in increasing adsorption capacity of Pb (II). MBC had higher adsorption capacity (112.3 mg/g) and faster removal rate (0.0081 g mg−1 min−1) than those of RhBC (41.2 mg/g and 0.00025 g mg−1 min−1). Modified RhBC can remove more than 99% of Pb (II) from wastewater and it could be utilized for three cycles with a removal performance of over 90%. In addition, the Pb adsorption mechanism by using MBC was proposed and the practical application of MBC for the treatment of wastewater in Vietnam was discussed. [Display omitted] • Alginate modified rice husk biochar (MBC) was used for Pb (II) removal in wastewater. • MBC had higher adsorption capacity (112.3 mg/g) as compared to others adsorbents. • More than 99% of Pb (II) in wastewater sample was removed by MBC. • MBC still has high efficiency of Pb (over 90%) after 3 times reused. [ABSTRACT FROM AUTHOR]

Background: Economic benefit has been analyzed for the yield of farming products when designing a farming system, while waste treatment also generates profitable energy products for this system. The economic factor is decisive in decision-making for applying waste treatment solutions for a small-scale farming system. A household farming system in the Mekong Delta generates many kinds of organic wastes, but most of the agricultural waste resources are disposed of into the environment. Methods: This study approaches an analysis of economic–environmental–energy (EEE) efficiency for waste treatment of an integrated livestock-orchard (LO) system on a household scale in the Mekong Delta. This novel analysis method is based on the energy content of biomass and its cost. The EEE efficiency is optimized to gain objective functions regarding energy yield efficiency, system profit, and CO2 sequestration for the treatment model. The algorithms are built for optimizing these objective functions. Results: The optimization results show the treatment model of pyrolysis and pelleting gain all the objective functions with high efficiency. The model is efficiently applied for the LO system that generates more than 100 kg of orchard residues and 3000 kg of pig manure. The system with a charcoal oven and pellet machine is capable to gain energy efficiency due to its potential biofuel products, such as biochars and pellet products. A treatment model of composting, pyrolysis, and pelleting gives the best performance of overall EEE efficiency. Conclusions: This work has proven economic benefits from integrating biogas tank, charcoal oven, and pellet machine in an integrated LO system. The system contributes not only for reducing CO2 emissions but also for supplementing secondary renewable bioenergy, as well as for increasing incomes and thus supporting livelihoods for the local farming households. [ABSTRACT FROM AUTHOR]

This study investigates carbon stability of biochars produced from wood, herbaceous, and fruit agricultural waste products from southern Vietnam. The biochars were produced by pyrolysis to 500 °C, 700 °C, and 900 °C at a heating rate of 10 °C/min. Organic geochemistry and petrology have well-established measurable parameters that define degree of preservation of organic carbon in the Earth's crust. These parameters are utilized, comparatively, to infer the organic carbon stability in biochars relative to that preserved in the geological carbonaceous rocks. The stability of carbon was assessed by measuring incident-light random reflectance (%R o) to determine the degree of thermally induced aromatization/ordering of the biochar carbon molecules. Additionally, the organic carbon content of the biochars was quantitatively separated into reactive and non-reactive carbon fractions based on thermodynamic stability of C H and C O bonds. The results show increasing carbon stability with increasing pyrolysis temperature and indicate high stability has been achieved at 700 °C and 900 °C where the biochars have the highest total organic carbon (TOC) contents and lowest Hydrogen Index values. Occurrence of a small quantity of readily degradable, labile free hydrocarbons (soluble organic matter; SOM) is due to condensation of the thermally generated hydrocarbons on the surfaces of the biochars. This fraction is minimized in the biochars produced at 700 °C and 900 °C due to volatilization of the free hydrocarbons at higher pyrolysis temperatures. The relatively substantial content of labile hydrocarbons associated with particulate organic matter (POM) in the 500 °C produced biochars is attributed to the incomplete pyrolyzation of the feedstock at this temperature. This fraction declines to near zero at 700 °C and 900 °C as complete carbonization is achieved at these higher temperatures. The overall carbon budget within the biochar shows that irrespective of the biochar type, over 97% of the TOC consists of highly refractory, residual carbon that geochemically is considered to possess long-term stability ("inert"). This is further underpinned by a pronounced increase in biochar mean random reflectance from <2.33% at 500 °C to >4.35% when pyrolyzed at 700 °C, indicating a highly polyaromatized condensed carbon structure. Rice husk is an exception as it yields a mean reflectance of 4.55% at 500 °C suggesting that pyrolysis temperature is not the only factor controlling %R o and hence carbon stability. Furthermore, the biochar compositions show a relationship between feedstock and pyrolysis temperature. The biochar morphotype composition changes significantly with increasing temperature, but the analyzed biochars are all dominated by fusinoid/solid (primarily fusinoid) morphotypes with the highest initial quantity recorded at 500 °C. This quantity decreases with increasing pyrolysis temperature while porous morphotypes (tenuinetwork, crassinetwork, mixed porous, mixed dense) increase. Variations in morphotype composition observed between the biochars is attributed to the structural nature of the feedstocks. [ABSTRACT FROM AUTHOR]

Despite being a promising biomass source for gasification, the practical use of rice straw in Vietnam is hindered by its low gasification efficiency. This study introduces an innovative approach by integrating the production of syngas and CO 2 adsorbent during the gasification process of rice straw, departing from the conventional focus solely on improving gasification efficiency. Results showed that the gasification of rice straw, conducted in the 20 kWe commercial gasification system (PP20 All Power Lab), attained a thermal conversion efficiency of 58.7%. Syngas produced exhibited consistent composition, with CO and H 2 content ranging from 12.1% to 15%, CO ranging from 16.9% to 22.1%, and CH 4 ranging from 1.9% to 3.9% throughout the operation, demonstrating relative stability. Notably, a considerable amount of residual char, accounting for 22.1 wt% of the initial feedstock, was generated. Characterized by notable traits such as high surface basicity, aromaticity, and a dense concentration of (ultra-)micropores, the residual char demonstrates suitability for applications in CO 2 adsorption. In controlled laboratory conditions (25 °C, 1 atm, without heat-mass transfer limitations), the adsorption capacity reached 1.2 mmol g−1. Transitioning to more practical conditions (40 °C, 1 atm, within a 2-cm adsorbent bed subject to diffusion constraints), the CO 2 adsorption capacity of the residual char ranged between 2% and 4.8% of the adsorbent's weight, while the CO 2 /N 2 selectivity measured between 25.5 and 29.7. These findings underscore the significant potential of integrating syngas and CO 2 adsorbent production through rice straw gasification, indicating a promising avenue for sustainable energy and carbon capture technologies. [Display omitted] • Stable syngas quality obtained throughout rice straw gasificatiom. • Use of residual char after gasification as cost-effective and scalable CO 2 adsorbents. • CO 2 capture capacities reached up to 1.2 mmol g−1 at 25 °C, 1 atm. • Potential for cascading use of rice straw for energy and adsorbent production. [ABSTRACT FROM AUTHOR]

Cassava starch production is a key industrial production of Tay Ninh province, Vietnam. However, this production chain has also caused many negative impacts on the environment. This study applied the principles of circular economy to analyze the waste streams via linear programming method for cassava starch circular production chain towards zero waste emission. The results show that the cassava starch indutry can achieve the goals of zero electricity, zero waste, and zero fossil energy by re-planning the production chain. The chain's output products are 517.5 tons of bio-oil/year, 206.7 thousand tons of biochar/year, 190.0 thousand tons of dry pulp/year, 10 million m3/year of liquid fertilizer. In order to increase further the value of the chain in the circular economy, future research needs to study the feasibility of a solution to reuse wastewater to produce microalgae, as well as evaluate the effectiveness of these methods. The optimization method applied in this study can also be extended to similar agricultural chains properties such as rice processing, sugar cane, etc. [ABSTRACT FROM AUTHOR]

Activated carbon is produced from Burmese grapes using NaOH as the activator under microwave irradiation. Through scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction analysis, and Brunauer–Emmett–Teller analysis methods, the activated carbon material is found to have a rough and uneven surface with the formation of pores, an amorphous structure, and possesses hydroxy, C–H, carbonyl, alkene, and ether functional groups. The surface area (478.5 m2 g−1) and pore size (about 3.4 nm) are calculated from the adsorption N2 equation. The adsorption mechanism of activated carbon is evaluated and follows a pseudo-first-order kinetic model (large single adsorption) and the Langmuir isotherm model (physical interaction). The factors affecting ciprofloxacin adsorption using activated carbon derived from Burmese grapes are also evaluated and optimized by the response surface method model based on influencing factors including the contact time, the solution pH, the antibiotic concentration, and the material dosage. The optimal parameters are as follows: pH = 6.26, concentration = 58.9 mg L−1, content = 0.15 g L−1, time = 54 min. Under optimal conditions, the adsorption capacity predicted from the model is 191.33 mg g−1 with an efficiency of 41.35%. [ABSTRACT FROM AUTHOR]

Durian is one of the most valuable and expensive fruits in Vietnam and Southeast Asia. Leaf nutritional disorders are considered to be causes of reductions in fruit yield and quality. However, studies on the nutritional balance in durian leaf are limited. In this study, we used the DRIS method for leaf limitation nutrient diagnosis at the stage 2 months before durian flowering. Our objectives were to (i) establish DRIS norms for the macronutrients (N, P, K, Ca, Mg, and S) in durian leaf and (ii) determine nutrient value ranges that are insufficient or excessive in durian production. A total of 180 leaf samples were collected and examined from 90 durian orchards cultivated on alluvial soils in the Vietnamese Mekong Delta. The results indicate that DRIS establishment for durian was highly reliable due to the significant positive correlation (r > 0.5) among nutrient indices. The limiting nutrients in durian leaf at the investigation stage were S, Mg, Ca, and P, where S and Mg were the most deficient. The optimal ranges of nutrients in durian leaf were determined and recommended in this study. Further studies are necessary to validate the efficiency of DRIS using nutrient omission trials under durian cultivation. [ABSTRACT FROM AUTHOR]

Vietnam's Mekong Delta region contains a sizable amount of acid-sulfate soil, which has properties that harm plants, such as low pH, aluminum and iron toxicity, hydrogen sulfide and sulfate acid. The study aims to gather helpful information about the problems with acid sulfate soils' chemical makeup so that suggestions can be made for improving these soils in the Mekong Delta. These methods mainly review studies and projects on the properties, constraints and management improvement of acid-sulfate soils and recommend the proper methods for sustainable use. The Mekong Delta contains many sulfidic or acid-sulfate-producing materials. Soils that contain acid sulfate are especially vulnerable to the consequences of climate change. Therefore, evaluating and predicting how acidic soil impacts soil quality and the affected factors such as drought, water scarcity, rainstorms, floods and saltwater intrusion are essential. Selecting cultivars that can withstand acid sulfate or salt is easy and inexpensive. Designing appropriate farming models is necessary in the interim. To correctly manage and exploit acid sulfate soils in the current situation, one must also be aware of their distribution, physicochemical makeup and biological properties. [ABSTRACT FROM AUTHOR]

Vietnam heavily relies on pork as its primary source of animal protein. Traditional farming methods, characterized by small-scale operations, dominate the industry. However, challenges such as rising feed costs, disease outbreaks, and market volatility are prompting many farmers to abandon their businesses. Recognizing the pivotal role of the swine sector in both economic development and nutrition, authorities must intervene to prevent its collapse. In developed nations, smart pig farming, utilizing technologies like sensors and cameras for data collection and real-time decision-making, has significantly improved health and productivity. These technologies can detect subtle indicators of animal well-being, enabling prompt intervention. This review aims to analyze the drivers of Vietnam's swine farming, identify existing production system flaws, and explore innovative precision farming methods worldwide. Embracing precision farming promises to enhance Vietnam's competitiveness in export markets and bolster consumer confidence. However, reliance solely on expensive foreign technologies may benefit large-scale farms, leaving smaller ones behind. Therefore, fostering local innovation and validating cost-effective solutions will be crucial for the sustainable growth of small- and medium-scale pig farming in Vietnam. [ABSTRACT FROM AUTHOR]

Landfills have the potential to contribute to mercury (Hg) pollution, due to the burial of waste containing mercury. Mercury from domestic waste can enter the soil surrounding landfills through surface runoff and leachate. In this study, we assessed the levels of Hg in the paddy soil around the Nam Son landfill, the largest landfill in the North of Vietnam, during both rainy (September 2021) and dry (January 2022) seasons. The concentration of Hg was in the range of 20.5 to 79.7 μg/kg dry w.t. in Bac Son and Nam Son, and 16.6 μg/kg dry w.t. at a higher reference site. In most of the samples, the rainy season showed higher Hg concentrations than the dry season. Soil samples taken closer to the landfill exhibited higher levels of Hg contamination compared to those in more distant paddy areas, suggesting a decreasing trend of Hg concentration as one moves away from the pollution source. Additionally, Hg concentration was found to decrease vertically from the surface, with the higher value observed in the surface layer (0–5 cm), and the lower in the bottom layer (20–25 cm). The geo-accumulation index showed that all the sampling points were moderately to heavily polluted, indicating that Hg was lost from the waste source in the landfill. This study provides valuable insights into the spatial and vertical distribution of Hg pollution in the topsoil and highlights the importance of managing and assessing the risks of Hg-containing waste. [ABSTRACT FROM AUTHOR]

Roselle is a potential crop in Vietnam due to its wide adaptation and many uses. In Thua Thien Hue province -- Central Vietnam, the roselle has been grown widely at Phong Dien district. However, local people were growing on their experience and mainly using inorganic fertilizers, which had affected the crop yield partly. In order to towards environmentally friendly and contribute to completing the growing process to expand the safe material area for roselle, the experiments were carried out during 2021 and 2022 to evaluate the effects of microbial organic fertilizer doses and planting density on the growth, development and yield of roselle. The experiment consisted of twelve treatments, with three doses of microbial organic fertilizer (0, 0.5, 1.5 tons/ha) and four planting densities (21000, 24000, 28000, 33000 plants/ha), arranged in a split-plot design with three replications for each treatment. The results showed that in the 0.5 tons/ha of microbial organic fertilizer application treatment and planted at 33000 plants/ha had the highest yield per plant in both crops (568.04 and 590.04 g/plant), with yields of 20.98 and 20.56 tons/ha, respectively. Therefore, it could be recommended to use that amount of microbial organic fertilizer and plant density in the process of growing roselle in Thua Thien Hue and similar ecological regions. [ABSTRACT FROM AUTHOR]

Sustainable development is a subject of study and consideration by scientists and policymakers, especially the sustainable development of the night-time economy. The night-time economy refers to the various economic activities and businesses that primarily operate during the evening and night hours, typically from 6 p.m. until early morning. It includes a diverse range of sectors such as entertainment, dining, hospitality, and nightlife, with establishments such as bars, clubs, restaurants, theaters, and live music venues playing a significant role. The development of the night-time economy refers to the process of managing and promoting the growth of economic activities during the evening and night hours in a manner that balances economic, social, and environmental considerations. Therefore, the paper aimed to identify the factors affecting the night-time economy in Hanoi to achieve the sustainable development of this economy. The paper processed and analyzed the data using SPSS Statistics 26.0 software. The quantitative study included (1) testing the suitability of the scale for the variables using Cronbach's alpha, (2) analyzing the EFA factors to check the convergence of the observed variables and the separation between the independent variables, (3) checking the correlation to evaluate the problem of multicollinearity of the model, and (4) performing regression analysis to evaluate the impact of the factors on night-time economic development in Hanoi City. The empirical results showed that the variables positively impacted night-time economic development in Hanoi. However, the study found differences in the levels of their impact. Among the four factors, factor 3 (promotion and sharing) had the strongest impact on night-time economic development, followed by factor 2 (city infrastructure and safety), factor 1 (institutions and environment), and factor 4 (nature and resources). The empirical results will help policymakers promote the sustained development of the night-time economy in Hanoi, Vietnam. [ABSTRACT FROM AUTHOR]

Rapid urbanization led to significant land-use changes and posed threats to surface water bodies worldwide, especially in the Global South. Hanoi, the capital city of Vietnam, has been facing chronic surface water pollution for more than a decade. Developing a methodology to better track and analyze pollutants using available technologies to manage the problem has been imperative. Advancement of machine learning and earth observation systems offers opportunities for tracking water quality indicators, especially the increasing pollutants in the surface water bodies. This study introduces machine learning with the cubist model (ML-CB), which combines optical and RADAR data, and a machine learning algorithm to estimate surface water pollutants including total suspended sediments (TSS), chemical oxygen demand (COD), and biological oxygen demand (BOD). The model was trained using optical (Sentinel-2A and Sentinel-1A) and RADAR satellite images. Results were compared with field survey data using regression models. Results show that the predictive estimates of pollutants based on ML-CB provide significant results. The study offers an alternative water quality monitoring method for managers and urban planners, which could be instrumental in protecting and sustaining the use of surface water resources in Hanoi and other cities of the Global South. [ABSTRACT FROM AUTHOR]

Water sources for irrigation systems in the Red River Delta are crucial to the socioeconomic growth of the region's communities. Human activities (discharge) have polluted the water source in recent years, and the water source from upstream is limited. Currently, the surface water quality index (WQI), which is calculated from numerous surface water quality parameters (physical, chemical, microbiological, heavy metals, etc.) is frequently used to evaluate the surface water quality of irrigation systems. However, the calculation of the WQI from water quality monitoring parameters remains constrained due to the need for a large number of monitoring parameters and the relative complexity of the calculation. To better serve the assessment of surface water quality in the study area, it is crucial and essential to conduct research to identify an efficient and accurate method of calculating the WQI. This study used machine learning and deep learning algorithms to calculate the WQI with minimal input data (water quality parameters) to reduce the cost of monitoring surface water quality. The study used the Bayes method (BMA) to select important parameters (BOD5, NH4+, PO43−, turbidity, TSS, coliform, and DO). The results indicate that the machine learning model is more effective than the deep learning model, with the gradient boosting model having the most accurate prediction results because it has the highest coefficient of determination R2 (0.96). This is a solid scientific basis and an important result for the application of machine learning and deep learning algorithms to calculate WQI for the research area. The study also demonstrated the potential of artificial intelligence algorithms to improve water quality forecasting compared to traditional methods with minimal cost and time. [ABSTRACT FROM AUTHOR]

Tea is a very important cash crop in Vietnam as it provides crucial income and employment for farmers in poor rural areas. Unfortunately, the dominance of long‐term, conventional tea cultivation has caused severe soil health degradation and environmental pollution. At the same time, as tea production may provide a better net income compared with other annual crops such as rice and vegetables, farmers have been converting parts of their allocated land to cultivate tea plants. Little is known about the benefit of agroecological management as an alternative to conventional tea management practices, and thus, there is a need to understand how it can improve tea yields, quality and the livelihoods of the farmers. Conducted in Northern Vietnam from 2019 to 2022, this study examined the impacts of agroecological tea management practices on soil health indicators, tea yield and quality, and net income of tea farmers. We showed that agroecological management practices significantly enhanced soil organic matter by 0.8% and soil pH by 0.5 units on average. Conversely, conventional management based on chemical fertilizer applications, significantly increased soil total nitrogen by 0.15%–0.2%. No significant differences were observed between soil texture and other soil chemical characteristics. Soil biological parameters were also significantly higher in agroecological tea soil and root samples than in conventional tea plots. Average AMF frequency and intensity of the agroecological tea roots were 98% and 37%, respectively, compared with 73% and 15% of the conventional tea roots. Likewise, soil macrofauna and mesofauna abundance in the agroecological tea plantations was 76 individuals/m2 and 101 individuals/100 g fresh soil on average, respectively, while that of conventional tea farms were 34 and 63 individuals/100 g fresh soil, respectively. Interestingly, a comparison between the converted and nonconverted lands did not show any significant effect of the conversion on soil physicochemical and biological characteristics, apart from tea root AMF colonization. Conventional tea management consistently resulted in higher tea yield and yield components, even though the differences were not always statistically significant. Despite lower tea yields, agroecological tea adopters earned around USD 8400 ha/year more than the farmers still practicing conventional management. This study shows that it is economically and environmentally more sustainable to produce organic tea than conventional tea, and our results should encourage more farmers to adopt such agroecological practices in Northern Vietnam. [ABSTRACT FROM AUTHOR]

The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water <2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was >80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms. [ABSTRACT FROM AUTHOR]

The prevalence of microplastics (MPs) in the environment has had a significant impact on ecosystems and posed a major threat to human health. This study investigated the distribution and characteristics of MPs in the Nhue - Day River basin in Vietnam, which is a critical source of biodiversity and used to support the economic growth of about 12 million people. The effect of seasonal variation and anthropogenic activities on the MP abundance was assessed. The findings revealed that the MPs abundance was significant in this study area. The average abundance of MPs in the dry season (754 items/m³) was insignificantly higher than that in the rainy season (706 items/m³) with n=9. The range in the abundance of MPs in the dry and rainy seasons was 49-2,827 and 400-1,133 items/m³, respectively. Microplastics in fiber forms were dominant in both seasons. The majority of the collected MPs were in the 0.5-2.0 mm size range, varying from 71% to 100% of the total MPs depend on sampling point. The total percentage of MPs size 0.3-0.5 mm in the dry season was 56.97% compared to 119.85% in the rainy season, indicating that the MPs were broken into smaller pieces due to UV exposure and weather conditions. Colored items occupied the majority of the MPs. This study can be used to gain a better knowledge of MP pollution in Vietnam's river water. [ABSTRACT FROM AUTHOR]

The owners of SMEs in Vietnam mainly focus on business performance in the short term. In recent years, FDI firms have demonstrated interest in both business efficiency and sustainable development. These issues have attracted the attention of scientists and policy makers in Vietnam. Therefore, this study aimed to determine the factors affecting the performance of small and medium enterprises in Vietnam regarding the Sustainable Development Goals (SDGs). Using the latest published survey data up to March 2022 for food and beverage, wood and steel foreign direct investment enterprises, combined with a data envelope analysis model in step one and Tobit regression in step two, the results from this quantitative study are as follows: (1) the production efficiency index of Vietnamese FDI enterprises ranges from 82.5% to 89% depending on the industry (assuming variable output to scale); (2) the factors financial leverage, renewable consumption, scale and operating time are related to the performance of FDI enterprises, and have a positive effect on performance; and (3) financial leverage and renewable consumption can generally boost a firm's performance in the case of FDI SMEs in the food and beverage, wood and steel industries. This research also suggests some solutions to achieve the Sustainable Development Goads (SDGs) in the FDI SMEs of Vietnam. [ABSTRACT FROM AUTHOR]

Peanut is an important annual crop in sandy soil of Central Vietnam. Organic fertilizer application plays a key role in improving peanut yield and soil quality. However, research on cattle manure is still limited in sandy soil for peanut crop. Trial consisted of 10 fertilizer treatments with two factors including two application methods and five ratios of inorganic fertilizer and manure and rice straw combinations. They were arranged in a split plot design with three replicates during the spring and summer season of 2021 on the sandy soil at Cat Trinh commune, Phu Cat district, Binh Dinh province, Vietnam. The aims of the study were to evaluate the efficiency of different combinations of organic amendments on the yield of peanut and to examine possible short-term changes in soil characteristics as a result of organic amendments application. The study results showed that application methods and different organic treatments gave higher yields compared with application of inorganic fertilizer alone. The highest peanut yield was found in the application of organic fertilizer from cattle manure+rice straw (1:0.5) and row application with (2.80-3.85 t/ha), increasing (21-27%) compared with application of inorganic fertilizer alone in surface application method and seasons. Cattle manure application improved some soil chemistry properties after the experiment such as OC, CEC, total N, P2O5 and K2O. In conclusion, incorporation of different types of organic amendments improved peanut yield and soil properties more than application of inorganic fertilizer alone. [ABSTRACT FROM AUTHOR]

Shade trees may have contrastive effects on Robusta coffee (Coffea canephora Pierre ex A. Froehner) yield, which may be additionally influenced by soil properties and reproductive stages of the plant. The current study is aimed at examining the interaction effects of shade trees, soils with different properties, and reproductive stages on coffee yield and identifying key factors influencing the yield. The current study was conducted in Dakha, Kontum of Vietnam on 133 farms, randomly selected from two soils, and two reproductive stages of coffee plants planted with and without shade trees. The coffee yield was measured, and surface soil samples were taken from these farms to be analyzed for 16 variables. The results showed that shade trees enhanced coffee yield significantly (by 28%) in the young reproductive stage but exhibited an insignificant effect in the old stage. The silt fraction, total nitrogen, cation exchange capacity, and shade trees were key factors determining 52% of the coffee yield in the sandy clay loam soil, while silt content and shade trees determined 23% of the yield in the clay soil. These findings suggest that shade trees, together with some soil properties, should be considered to improve coffee production under a tropical monsoon climate region. [ABSTRACT FROM AUTHOR]

High ammonium concentration in groundwater in Viet Nam is a threaten consequence to Vietnamese people in suburban and rural areas. Coconut coir is an economic waste of Viet Nam's agriculture with million tons generated every year. In this work, NaOH treatment of raw coconut coir (RCC) was implemented to obtain activated biomaterial (NaACC) for evaluation of ammonium adsorption from synthetic and ground waters. First, the effects of adsorbent dosage, initial ammonium concentration, reaction time, temperature on adsorption performance, adsorption isotherm, and kinetics for ammonium‐contained synthetic water were investigated. Second, the ammonium adsorption performance of NaACC from a natural groundwater was also evaluated. The removal efficiencies of ammonium were 49.5, 60.6, and 66.7% with maximum adsorption capacities of 0.51, 0.67, and 0.74 mg/g at temperatures of 30, 40, and 50°C, respectively, at pH 7.0, NaACC dose 40 g/L, initial ammonium concentration 40 mg/L, and reaction time 144 h. The NaACC displayed the best ammonium adsorption following Langmuir isotherm (R2 = 0.9990) and pseudo‐second‐order kinetic model (R2 = 0.9989). The NaACC also exhibited a good ammonium adsorption in natural groundwater with removal efficiency and adsorption capacity of 82.6% and 0.77 mg/g, respectively. Particularly, NaACC can be regenerated up to three cycles for consecutive adsorption of ammonium in groundwater without loss of its adsorptive performance. Therefore, NaACC derived from agricultural wastes was a potential biomaterial for cleaning ammonium from contaminated groundwater. [ABSTRACT FROM AUTHOR]

The 2,3,7,8-tetrachlorodibenzodioxin (TCDD), a contaminant in Agent Orange released during the US–Vietnam War, led to a severe environmental crisis. Approximately, 50 years have passed since the end of this war, and vegetation has gradually recovered from the pollution. Soil bacterial communities were investigated by 16S metagenomics in habitats with different vegetation physiognomies in Central Vietnam, namely, forests (S0), barren land (S1), grassland (S2), and developing woods (S3). Vegetation complexity was negatively associated with TCDD concentrations, revealing the reasoning behind the utilization of vegetation physiognomy as an indicator for ecological succession along the gradient of pollutants. Stark changes in bacterial composition were detected between S0 and S1, with an increase in Firmicutes and a decrease in Acidobacteria and Bacteroidetes. Notably, dioxin digesters Arthrobacter, Rhodococcus, Comamonadaceae, and Bacialles were detected in highly contaminated soil (S1). Along the TCDD gradients, following the dioxin decay from S1 to S2, the abundance of Firmicutes and Actinobacteria decreased, while that of Acidobacteria increased; slight changes occurred at the phylum level from S2 to S3. Although metagenomics analyses disclosed a trend toward bacterial communities before contamination with vegetation recovery, non-metric multidimensional scaling analysis unveiled a new trajectory deviating from the native state. Recovery of the bacterial community may have been hindered, as indicated by lower bacterial diversity in S3 compared to S0 due to a significant loss of bacterial taxa and recruitment of fewer colonizers. The results indicate that dioxins significantly altered the soil microbiomes into a state of disorder with a deviating trajectory in restoration. [ABSTRACT FROM AUTHOR]

Agricultural production is one of the main sources of anthropogenic greenhouse gas (GHG) emissions, contributing 50% and 60% of CH4 and N2O emissions, respectively. This study evaluated the rice yield and components, the CH4 and N2O emissions and the global warming potential between the triple rice (R-R-R) and sesame-rice rotation (S-R-R) systems in Can Tho city, Vietnam. The experiments were conducted in three cropping seasons: spring-summer 2016, summer-autumn 2016, and winter-spring 2016–2017. The results showed that there was no significant difference in the yield components and grain yield between the triple rice and sesame-rice rotation systems. The application of a sesame rotation in rice-based system could reduce the CH4 and N2O emission by 30.5% and 18.7%, respectively. The global warming potential in the S-R-R rotation was 9 860 kg CO2e/ha, significantly lower than the R-R-R rotation (12 410 kg CO2e/ha) by 20.6%. These results show that the S-R-R rotation has the potential to mitigate the GHG emissions, especially CH4, which contributes a large amount of emissions in the rice cultivation. [ABSTRACT FROM AUTHOR]

High economic and tourism growth demand extensive energy production that needs the energy creation industry's attention and demands the researchers' and policymakers' emphasis. Hence, the present study examines the impact of economic and tourism growth on renewable energy production (REP) in Vietnam. The present research has taken the gross domestic product (GDP), exports, human capital, and employment rate to measure the economic growth, while international tourism receipts and expenditures have been used to measure the tourism growth. The secondary data have been extracted from 1983 to 2020 using World Development Indicators (WDI) database. The Nonlinear Autoregressive Distributed Lagged (NARDL) model has been applied to investigate the linkage between the constructs. The findings indicated that GDP, exports, human capital, employment rate, international tourism receipts, and expenditures have a significant and positive relationship with REP in Vietnam. These results guide the regulators while making regulations related to the extensive energy production in return for high economic and tourism growth. [ABSTRACT FROM AUTHOR]

Rainwater harvesting (RWH) systems can be used to produce drinking water in rural communities, particularly in developing countries that lack a clean drinking water supply. Most previous research has focused on the application of RWH systems for individual urban households. This paper develops a yield-after-spillage water balance model (WBM) which can calculate the reliability, annual drinking water production (ADWP) and benefit–cost ratio (BCR) of a community-scale RWH system for rural drinking water supply. We consider multiple scenarios regarding community aspects, including 150–1000 users, 70–4800 kL rainwater storage, 20–50 L/capita/day (LCD) drinking water usage levels, local rainfall regimes and economic parameters of Australia (developed country) and Vietnam (developing country). The WBM analysis shows a strong correlation between water demand and water supply with 90% system reliability, which allows both Australian and Vietnamese systems to achieve the similar capability of ADWP and economic values of the produced drinking water. However, the cost of the Vietnamese system is higher due to the requirement of larger rainwater storage due to larger household size and lower rainfall in the dry season, which reduces the BCR compared to the Australian systems. It is found that the RWH systems can be feasibly implemented at the water price of 0.01 AUD/L for all the Vietnamese scenarios and for some Australian scenarios with drinking water demand over 6 kL/day. [ABSTRACT FROM AUTHOR]

ZSM-5 zeolite was successfully synthesized from bentonite clay sourced from Lam Dong Province, Vietnam, using the hydrothermal method at 170 °C for 18 h. The synthesized ZSM-5 (SiO 2 /Al 2 O 3 ratio ~ 34) exhibited a single phase with high crystallinity (91.8%), and a clear and uniform shape. In a detailed examination of the synthesized material's Pb(II) adsorptive capacity, various factors were taken into account, including pH, interaction time, ionic strength, and the amount of adsorbent. Isotherms and kinetics were examined to elucidate the uptake behavior. Study results suggested that Pb(II) ion uptake by ZSM-5 was most appropriately described by the Sips isotherm and intraparticle diffusion kinetic models. The calculated maximum monolayer adsorption capacity according to the Langmuir isotherm model was 48.36 mg/g. Furthermore, the adsorption mechanisms of Pb(II) on ZSM-5 involving electrostatic interactions, ion exchange, and diffusion into pores were demonstrated using the analytical techniques before and after Pb(II) adsorption. These findings demonstrate that ZSM-5 synthesized from bentonite clay exhibits an excellent adsorption capacity for Pb(II), resulting in promising applications for treating drinking water or aqueous industrial waste containing Pb(II) ions., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

For effective management of water quantity and quality, it is absolutely essential to estimate the pollution level of the existing surface water. This case study aims to evaluate the performance of twelve machine learning (ML) models, including five boosting-based algorithms (adaptive boosting, gradient boosting, histogram-based gradient boosting, light gradient boosting, and extreme gradient boosting), three decision tree-based algorithms (decision tree, extra trees, and random forest), and four ANN-based algorithms (multilayer perceptron, radial basis function, deep feed-forward neural network, and convolutional neural network), in estimating the surface water quality of the La Buong River in Vietnam. Water quality data at four monitoring stations alongside the La Buong River for the period 2010–2017 were utilized to calculate the water quality index (WQI). Prediction performance of the ML models was evaluated by using two efficiency statistics (i.e., R2 and RMSE). The results indicated that all twelve ML models have good performance in predicting the WQI but that extreme gradient boosting (XGBoost) has the best performance with the highest accuracy (R2 = 0.989 and RMSE = 0.107). The findings strengthen the argument that ML models, especially XGBoost, may be employed for WQI prediction with a high level of accuracy, which will further improve water quality management. [ABSTRACT FROM AUTHOR]

Ammonium removal from drinking water to protect human and environmental health is one of the major global concerns. This study evaluates the performance of Purolite C100E, a commercial cation exchange resin, in eliminating ammonium in synthetic and real contaminated groundwater. The results demonstrate that the pH operation range of the resin for better ammonium removal is 3 to 8. Lower ammonium removal at low and high pH occurred due to competition from H+ and loss of ammonium as ammonia gas, respectively. Equilibrium data of ammonium removal fitted both the Langmuir and Freundlich isotherm models with the maximum Langmuir ion exchange capacities for initial ammonium concentrations of 10–200 mg/L and 50–2000 mg/L, reaching 18.37 mg/g and 40.16 mg/g, respectively. The presence of co-ions in the water reduced the ammonium removal efficiencies slightly (< 12%) in the order Mg2+ > Ca2+ > K+. The higher affinity of ammonium to adsorbent is due to its lower hydrated ionic radius and H-bonding. The maximum exchange capacity in the fluidized bed studies of the original Purolite C100E (bed height 27 cm, resin weight 75 g, initial ammonium concentration 17.4 mg/L, filtration velocity 0.5 m/h) was 10.48 mg/g. It progressively reduced slightly after three regeneration cycles to 8.79 mg/g. The column breakthrough data satisfactorily fitted the Thomas model. A household filter cartridge packed with 4 kg Purolite C100E (80 cm height) and operated at a filtration velocity of 1.9 m/h in Vietnam successfully reduced the initial 6 mg NH4+/L in groundwater (after sand filter pre-treatment) to well below the Vietnam drinking water standard (3 mg/L-QCVN 01:2009/BYT) continuously for 1 week, suggesting that such a filter can be adopted in rural areas to successfully remove ammonium from groundwater. [ABSTRACT FROM AUTHOR]

This study aimed to (i) select endophytic bacteria in maize root for its phosphorus solubilization ability and (ii) evaluate the efficacy of selected indigenous bacterial strains on soil fertility, phosphorus (P) uptake, growth, and maize yield. A total of 31 maize root samples were collected from An Phu District, An Giang Province, to isolate the bacteria. In addition, the pot experiment was conducted with nine treatments of (i) 100% P of the recommended fertilizer formula (RFF), (ii) 75% P of the RFF, (iii) 50% P of the RFF, (iv) 25% P of the RFF, (v) 75% P of the RFF plus a mixture of the 3 selected strains, (vi) 50% P of the RFF plus a mixture of the 3 selected strains, (vii) 25% P of the RFF plus a mixture of the 3 selected strains, (viii) 0% P of the RFF plus a mixture of the 3 selected strains, and (ix) 0% P of the RFF plus none of the 3 selected strains. The results identified 72 isolates from LGI medium. All isolates were screened in a broth medium at pH 5.0, but only 16 isolates obtained OD660 > 0.5. All 16 isolates were able to solubilize various insoluble P fractions. Of those, strain ASD-21 had the highest P solubilization ability for the insoluble Al-P compound. Strains ASD-08 and ASD-21 had the highest Fe-P concentration at 39.8-41.5 mg P L-1. Strains ASD-08 and ASD-21 had the highest Ca-P concentration (46.6-51.3 mg P L-1) for 48 h of incubation. They were identified as Enterobacter spp. Results also showed the application of a mixture of strains ASD-08, ASD-10, and ASD-21 increased soil fertility by increasing phosphorus content by 13.7 mg P kg-1 and replacing 25% of P fertilizer, but this mixture did not change maize yield. [ABSTRACT FROM AUTHOR]

Assessment of ecosystem services is vital for successful natural resource allocation; however, these have been less studied within Vietnam. This study estimated the ecosystem services value (ESV) and its change in Cham Chu nature reserve, Vietnam using a benefit transfer method. Ecosystem service values estimation and trend analyses were carried out based on land use and land cover datasets from 1986, 1998, 2007, and 2017, with their corresponding global value coefficients. The results revealed that the total value of ecosystem services in Cham Chu was approximately 64.4, 63.9, 60.7, and 63.4 million USD in 1986, 1998, 2007, and 2017, respectively. Changes have also occurred in the values of individual ecosystem service functions. From 1986 to 2017, ecosystem service functions showed significant decreases in gas regulation, pollination, biological control, water regulation, water supply, and food production of 62.9%, 51.2%, 44.4%, 24.7%, 23.1%, and 13.0%, respectively. We conclude that the loss of ESV is a result of ecological deterioration in the studied landscape, and we propose further research to examine future solutions and establish action strategies. In summary, the research approach methodology developed can be used by land managers and planners in Vietnam as a guideline to estimate the importance of ecosystem services in Vietnam. [ABSTRACT FROM AUTHOR]

The implementation of climate change adaptation and greenhouse gas emissions (GHGs) mitigation not only results in synergy and co-benefits of climate change adaptation and mitigation but also leads to socioeconomic, environmental, and institutional benefits. The main objective of the study is to develop the methodology to assess the co-benefits of climate change response actions in nationally determined contributions (NDCs) as well as Vietnam's sustainable development goals (SDGs). During this research study, it was found that GHG mitigation can lead to an adaptation rate of 2.9 (on a scale of 5), which is higher than that of climate change adaptation to climate change mitigation (which is a rate of 1.9 on a scale of 5). Most of the overall benefits of GHGs reduction are gained in the Land Use, Land-Use Change, and Forestry (LULUCF) sector. As for the climate change adaptation, the overall benefits can be received most in the agricultural and the rural development sector. Moreover, the implementation of climate change actions also facilitates the achievement of SDGs. [ABSTRACT FROM AUTHOR]

Ehretia asperula (E asperula) is a well-known traditional medicinal plant in Vietnam with potent activity against a wide range of diseases, including hepatitis B and various cancers. Although E asperula has been used in traditional medicine, the efficacy of E asperula and its bioactive components on retinal degenerative diseases has not been fully evaluated. In present this study, we found that ethanolic extracts of E asperula increased cell viability in retinal precursor cells exposed to glutamate/BSO-induced excitotoxicity/oxidative stress. The major responsible bioactive compounds were rosmarinic acid and methylrosmarinic acid. First, 10 known compounds were isolated from E asperula leaves. Their chemical structures were determined using 1D and 2D nuclear magnetic resonance, and compared with published data. Using high-performance liquid chromatography, we determined the content of 4 compounds in E asperula extract: rosmarinic acid, lithospermic acid B, astragalin, and kaempferol 3-rutinoside. The most abundant of these com)pounds was lithospermic acid B. The protective effects of the pure compounds and ethanolic extracts against excitotoxicity and oxi)dative stress-induced retinal cell death were tested in R28 cells. Both 70% and 95% ethanolic extracts of E asperula increased cell viability in these conditions. Rosmarinic acid and methyl rosmarinic acid were more effective at protecting against retinal cell death and elevated reactive oxygen species in cells subjected to glutamate/BSO-induced excitotoxicity/oxidative stress. These find)ings suggested that E asperula could potentially be used to treat retinal degeneration. [ABSTRACT FROM AUTHOR]

The Vietnam's agricultural sector had to challenge with its course and learned lessons of further development. Novel policy might be adopted to encourage the private investments and sectors in agriculture. Furthermore, an introduction of new models such as climate-smart or green agriculture and application of modern technology increased productivity at the same time and creating jobs for millions of agricultural workers and reversing the massive rural-urban migration flux. Vietnam's agricultural sector needs to maintain the reform momentum, particularly liberalization policy, and to boost up agricultural potential. Obstacles such as land limitation policy must be removed to enable large-scale production and encourage private investment in the agricultural sector. To avoid being trapped by its own success, Vietnam is now shifting the old development paradigm that focuses too much on the quantity to the quality of the agricultural production. The government makes major efforts to achieve at the same time agricultural growth, better livelihood of the farmer, and the development of the rural areas. However, Vietnam still needs to prepare a "transition strategy" to overcome the impact of the technological progress on the traditional agricultural workers. [ABSTRACT FROM AUTHOR]

Sands have favourable physical properties for harvesting peanut, but improving S and water use efficiency on these soils remains a challenge. We studied partial S balance in irrigated peanut crops on sands of Central Vietnam to identify key factors of S fertiliser management affecting S inputs and outputs. Field trials were conducted in the spring seasons of 2015 and 2016 to determine the effects of S application rates (0, 15, 30, 45 kg ha−1) on peanut yield and partial S balance. Sulfur balances were negative (−28.3 to 5.6 kg S ha−1) at rates < 30 kg S ha−1, while at higher rates of S fertiliser application that produced maximum pod yield (30–45 kg S ha−1), three of four sites showed neutral to slightly positive S balance (1.5–5.6 kg S ha−1). The negative partial S balance decreased with increasing S rates but was mostly attributable to the large S removal in peanut shoots (9.7–22.3 kg S ha−1) which are used on farms for animal feed. The negative partial S balance results in depletion of soil S reserves and hence efficient recycling of S on farms is critical for sustainable crop production on sands of VN. [ABSTRACT FROM AUTHOR]

CO2 emissions reduction from coal-fired power plants is an urgent issue in Japan, as well as around the world. The purpose of this study is to estimate the CO2 emissions and economy of using carbonized wood pellets produced overseas and co-fired at coal-fired power plants in Japan. We examined carbonized wood pellets produced in Canada and Vietnam, since those countries are major exporters of wood pellets for Japan. The results obtained are as follows: (1) The CO2 emissions and calculated cost per calorific value of carbonized wood pellets (CP25), which have a fixed carbon content of 25 wt.%, are lower than those of wood pellets at the port of import in Japan. When the fixed carbon of carbonized biomass is controlled at 25 wt.% or more via a carbonizer, sufficient pyrolysis gas (the heat source used for drying and carbonization without auxiliary fuel) can be obtained. (2) Carbonized wood pellets manufactured in Vietnam are more economical than those manufactured in Canada, since the resource of wood is less expensive and the transportation distance is shorter from Vietnam compared to Canada. (3) When carbonized wood pellets at CP25 are co-fired in coal-fired power plants, they do not affect the cost of the electricity generated, even if the carbonized pellets are blended at a high ratio. [ABSTRACT FROM AUTHOR]