The large number of vehicles plying in roads is the main cause of traffic jam and air pollution in Hanoi. In this study, the vehicle density and shares of different vehicle types, the traffic flow velocity and roadside air pollutants concentrations were monitored in Chua Boc street, a typical arterial road in the city. The shares of the motorcycle, car and bus fleets in the total on-road traffic in the street were 78.4-87.3, 12.3-20.2 and 0.4-1.4%, respectively. The high density of vehicles caused traffic jam during rush hours and considerably reduced the vehicle speed. The traffic flow velocity during non-rush and rush hours was found to vary from 26.4-34.5 and 10.3-12.1 km/h, respectively. The average concentrations of PM₁₀, PM_2.5, SO₂, NO₂, CO and NMVOC during the rush hours were the following: 117.1 ± 8.5, 65.2 ± 10.6, 113.5 ± 10.9, 138.5 ± 16.0, 6792 ± 998 and 451 ± 71 µg/m³, respectively, which were about 1.9-2.6 times above the levels during non-rush hours. The decrease in vehicle speed during rush hours were strongly correlated with the increase in concentration of PM₁₀ (R² = 0.732), PM_2.5 (R² = 0.685), SO₂ (R² = 0.578), NO₂ (R² = 0.738), CO (R² = 0.689) and NMVOC (R² = 0.747). High levels of these toxic air pollutants in Hanoi city posed a high health risk to humans. Facemask use was more popular among the motorcycle commuters and pedestrians, especially during rush hours, than among the people working for extended time period alongside of the street.

The increasing intensification of aquaculture systems requires the development of strategies to reduce their environmental impacts such as pollution caused by the discharge of nutrient rich sediments into local water bodies. Recycling of fish pond sediments (FPS) as fertilizer has been proposed as a possible solution that may also reduce the reliance on synthetic fertilizers. With a case study in the Mekong Delta, Vietnam, we determined suitable mixtures of striped catfish (Pangasianodon hypophthalmus) pond sediment (PPS) and locally sourced organic amendments of rice straw (RS), or common water hyacinth (WH) to fertilize cucumber plants (Cucumis sativus L.) in an integrated cucumber–giant gourami fish (Osphronemus goramy) farming system. Highest nutrient concentrations were found when mixing 30% PPS with 70% RS or WH. When used in combination with chemical fertilizer, it was found that a 25% to 75% reduction in chemical fertilizer application could be achieved, while also increasing cucumber yields, with the highest yields found when RS was used in organic amendments. In combination with the additional income from fish production, integrated farming systems such as that demonstrated in this study, may increase both farm income and production diversity.

The abundance of heat-trapping asphalt and concrete, smog, and heat emitted from buildings and vehicles is one of the major reasons for the prevailing high temperature, air and noise pollution in cities. Incorporation of green wall in buildings is considered to be an effective method to reduce temperature and mitigate environmental pollution. This study investigated and compared the performance of two types of climbing green wall (CGW) and paving green wall (PGW) vegetation for temperature and noise reduction. Besides, the biological characteristics of Parthenocissus tricuspidata and Sedum lineare Thunb were also analysed to substantiate the temperature and noise reduction performance of these plants. The results revealed that, the average temperature reduction by CGW and PGW were 4.9 ± 1.3 and 16.6 ± 7.4%, respectively, under no irrigation condition, and 18.4 ± 9.4 and 23.8 ± 8.7%, respectively, under irrigation condition. The noise reduction by CGW in high (75-80 dB), medium (50-55 dB) and low (30-35 dB) sound pressure level was 12.4, 7.5 and 5.7 dB, respectively, and 15.6, 9.3 and 7.0 dB, respectively, by PGW. The results demonstrated that green wall has an excellent effect on buildings towards temperature and noise pollution reduction.

Common porous concrete templates (CPCT) and advanced porous concrete templates (APCT) were employed in this study to construct wetlands for their applications in pollutant removal from storm runoff. The planting ability of the concrete was investigated by growing Festucaelata plants in them. Strength of the porous concrete (7.21 ± 0.19 Mpa) decreased by 1.8 and 4.9% over a period of six and twelve months, respectively, due to its immersion in lake water. The height and weight of Festucaelata grass growth on the porous concrete were observed to be 12.6–16.9 mm and 63.4–95.4 mg, respectively after a duration of 1 month. Advanced porous concrete template based constructed wetland (APCT-CW) showed better removal of COD (49.6%), TSS (58.9), NH₃-N (52.4%), TN (47.7%) and TP (45.5%) in storm water, when compared with the common porous concrete template based constructed wetland (CPCT-CW) with 20.6, 29.8, 30.1, 35.4 and 26.9%, respectively. The removal of Pb, Ni, Zn by the CPCT-CW unit were 28.9, 33.3 and 42.3%, respectively, whereas these were 51.1, 62.5 and 53.8%, respectively with the APCT-CW unit. These results demonstrate that the advanced porous concrete template in constructed wetland could be employed successfully for the removal of pollutants from urban storm water runoff.

This novel study on cement paste material was conducted with the aim of keeping up with the rapid development of urban construction and contributing to the continuous improvement of building materials to overcome environmental issues. In this study, several kinds of industrial waste were used to enhance the properties of cement paste for application in a marine environment with a tropical climate, such as in Vietnam. This study focuses on evaluating the properties of cement paste containing cement replacement combining 0–30% fly ash, 0–10% silica fume, and plasticizer accounting for 0.3% and 0.4% of the binder by mass. Water demand, chloride ion and sulfate ion permeability, and microstructural properties of the cement paste were determined by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM) and they were investigated after 28 and 56 days. The test results show that an optimum mixture could be obtained with the use of 20% fly ash, 10% silica fume (replacing Portland cement), and 0.4% plasticizer. The application of such materials to sea dikes affected by a tropical climate (characterized by heat, humidity, salty seawater, many big storms, large waves, and strong tides) was investigated for four years on the Vietnamese coast. The test results indicate that fly ash and silica fume can improve the corrosion and abrasion resistance of concrete in coastal areas with a tropical climate, such as in Vietnam.