Science and Technology Development Journal: Natural Science
The official jornal of Viet Nam National University Ho Chi Minh City
Sea level rise scenarios for Ho Chi Minh City in the context of the climate change
This work aimed to develope sea level rise (SLR) scenarios in Ho Chi Minh City (HCMC) to 2100, corresponding to the scenarios of RCP2.6, RCP4.5, RCP6.0, and RCP8.5 and the approach mentioned in the AR5 report of the Intergovernmental Panel on Climate Change (IPCC) through SIMCLIM software, and the local water level data (updated to 2015). The results showed that the SLR in the coastal area of HCMC increased gradually over the years as well as the increase in greenhouse gas scenarios. In the period of 2025-2030, SLR would increase relatively equally among RCP scenarios. SLR in 2030 would increase about 12cm as compared to sea level in the period of 1986-2005 in all RCP scenarios. By 2050, the average SLR for the scenarios of RCP2.6, RCP4.5, RCP6.0, and RCP8.5 would be 21 cm, 21 cm, 22 cm, and 25 cm, respectively. The corresponding figures for 2100 would bee 43 cm, 52 cm, 54 cm, and 72 cm, respectively. The research results provide an important basis for calculations and assessments of impact and vulnerability due to the climate change to socio-economic development in HCMC.
Application of constructed wetlands using Vetiveria zizanioides and Phragmites australis in the landfill leachate treatment
Constructed wetlands have been widely applied for removing pollutants in the leachate recently. In this study, constructed wetland system combined vertical flow and horizontal flow, using Vetiveria zizanioides L. and Phragmites australis, was set in a laboratory scale to assess the leachate treatment ability. The landfill leachate was added to the system with increasing concentration to evaluate the treatment ability by the time. The results showed that the removal efficiency reached the highest when the COD concentration was 575 mg/L, including BOD5 (96.48%), COD (83.24%), total nitrogen (91.43%), total phosphorus (77.84%), ammonia nitrogen (86.47%), and color (87.91%). Furthermore, the treated effluent quality reached the class A of the Vietnamese standard on industrial wastewater quality. Beside, when physicochemically treated leachate (coagulation – flocculation) (COD concentration was 1255.50 mg/L), was added to the system, the removing efficiencies remained stable by the time, with the efficiency of ammonia nitrogen removing (93.48%), BOD5 (94.86%), total phosphorus (96.67%), total nitrogen (95.81%). Besides, the treated effluent quality reached the class B of the Vienamese standard on industrial wastewater quality. On other hand, COD and color removing efficiencies were also high at the first stage and tended to reduce rapidly by the time. Therefore, the EM called Bayer Pond Plus added to the system could increase and substained the removing efficiencies of COD (66.61%), color (81.40%). The results of this study showed that constructed wetland system had potential in the landfill leachate treatment.
Characterizations and nitrate adsorption capacity of Amine-SiO2 material
Amine-SiO2 material (basically on silicon dioxide) was synthesized by the grafting method with triamine silane to form activated amine groups on the surface of SiO2 support and was applied as a novel adsorbent for nitrate removal from aqueous solution. The characterizations of Amine-SiO2 were determined by using TGA, FTIR, BET, SEM. Nitrate adsorption capacity and durability of Amine-SiO2 were compared with the anion exchange resin (Akualite A420 commercial). The results showed that Amine-SiO2 had high nitrate adsorption capacity, ~ 1.14 fold higher than the Akualite A420 ion exchange resin, based on the adsorption efficiency. This might be due to a strong affinity for nitrate ions of the activated amine groups on the surface of SiO2 support. In addition, the experimental results also proved that Amine-SiO2 material had good durability (stable performance after 10 regeneration times).
Vulnerability assessment due to the climate change in Vinh Long province
This work aimed to assess the vulnerability to the climate change (CC) in Vinh Long province till 2020. Inundation, saltwater intrusion (SI), drought, riverbank landslide, storm, temperature and precipitation were taken into consideration. In addition to the socialogical investigation, risk assessment matrix, adaptive capacity assessment methods, etc. the vulnerability to CC was evaluated via index method. Results showed that among 8 districts in the province, Long Ho, Vung Liem, Vinh Long city, and Tam Binh were the most vulnerable. Besides, sectors interested in the relationship to CC include agriculture, infrastructure, and landuse. Indicated vulnerable sectors and areas in the province were important factor for planning suitable coping measures, especially in the context of CC seriously increasing.
Ozone removal efficiency of the KI-denuder in the carbonyl sampling
In the carbonyl sampling of 2, 4- dinitrophenylhydrazine (DNPH) impregnated cartridge, the ozone removal was necessary because ozone reacted with the DNPH derivatives. A commercial ozone scrubber was usually used to remove O3. However, high humidity leaded to carbonyl compounds being trapped on the ozone scrubber before passing through the DNPH cartridge. The purpose of this study was to assess the ozone removal by KI-denuder under the climatic conditions of Ho Chi Minh City. Several parameters including air sampling flow rate and denuder length were optimized to achieve the highest removal efficiency. The optimum parameters of the KI denuder were the sampling flow rate of less than 1 L/min, and the denuder length of 20 cm. The effect of the initial O3 concentration on the removal efficiency was also investigated. Finally, the ozone removal efficiency of KI-denuder was compared to that of ozone scrubber when two devices were applied for the carbonyl sampling during field measurement. The results show that KI-denuder could be used to replace the ozone scrubber with high removal efficiency, particularly in high humidity condition. In conclusion, KI-denuder was effective, simple, easy to use and cheap. Therefore, it was encouraged to use in carbonyl sampling.
Assessment of people’s livelihood vulnerability under the impact of drought in Krongno district, Dak Nong province using livelihood vulnerability index
Krong No was evaluated that it was the most severely affected district in Dak Nong province under impacts of drought in 2015-2016. The objective of this study was to assess the people’s livelihood vulnerability in Krong No district in Daknong province by using Livelihood Vulnerability Index developed by Hahn et al. (2009) and field survey. The obtained results indicated that LVI of Krong No district reached to medium level (0.444). However, there was an unbalance point in major components of the LVI. The most vulnerable components were water (0.774) livelihood strategies (0.661), whereas, five other components were lower than 0.5. The descreasing order of the vulnerability was food, drought, social networks, health and sociodemographic profile. Another result showed that Quang Phu and Nam N'dir were two of five communes which were needed the support.
Multi-modal video retrieval using Dilated Pyramidal Residual network
Pyramidal Residual Network achieved high accuracy in image classification tasks. However, there is no previous work on sequence recognition tasks using this model. We presented how to extend its architecture to form Dilated Pyramidal Residual Network (DPRN), for this long-standing research topic and evaluate it on the problems of automatic speech recognition and optical character recognition. Together, they formed a multi-modal video retrieval framework for Vietnamese Broadcast News. Experiments were conducted on caption images and speech frames extracted from VTV broadcast videos. Results showed that DPRN was not only end-to-end trainable but also performed well in sequence recognition tasks.
Fine particulate matter (PM2.5) in Ho Chi Minh City: Analysis of the status and the temporal variation based on the continuous data from 2013-2017
Since 2013, the Ministry of Natural Resources and Environment published the revision of the “National Technical Regulation on Ambient Air Quality” (QCVN 05:2013/BTNMT), in which the fine particulate matter (PM2.5) was added to the QCVN. However, the status and the temporal variation of PM2.5 in Ho Chi Minh City (HCMC) have not been reported so far, especially based on the continuous and high time resolution measurements. The aim of this study was to analyze the status and the temporal variation of PM2.5 collected at the center of HCMC. Based on the composited PM2.5 data from the air monitoring station located at the University of Science, the average PM2.5 concentration was 28.0 ± 18.1 µg/m³ during 2013– 2017. The annual PM2.5 concentration in HCMC exceeded the acceptable limits of QCVN and WHO, highlighting a high human health risk. The PM2.5 concentrations showed the pronounced diurnal variation with the highest observed after the morning rush hour and the lowest during the midnight. In addition, a remarkable seasonal variation was observed with the highest and lowest PM2.5 occurring in dry and rainy seasons, respectively. This result highlighted the vital role of the rainfall events in reducing the PM2.5 level. Finally, from the analysis of the backward trajectories ending at the air monitoring station, we found that the air mass from the North and Northeast originating from China then passing through the areas (i.e. Binh Duong and Dong Nai provinces) with heavy industrial activities possessed a high PM2.5 level.
Calculation of the Orr-Sommerfeld stability equation for the plane Poiseuille flow
The stability of plane Poiseuille flow depends on eigenvalues and solutions which are generated by solving Orr-Sommerfeld equation with input parameters including real wavenumber and Reynolds number . In the reseach of this paper, the Orr-Sommerfeld equation for the plane Poiseuille flow was solved numerically by improving the Chebyshev collocation method so that the solution of the Orr-Sommerfeld equation could be approximated even and odd polynomial by relying on results of proposition 3.1 that is proved in detail in section 2. The results obtained by this method were more economical than the modified Chebyshev collocation if the comparison could be done in the same accuracy, the same collocation points to find the most unstable eigenvalue.
The research and fabrication of graphene quantum dots applied as the hole transporting layer in polymer solar cells
In this report, we studied and fabricated graphene quantum dots by improved the Hummer method using NH3 reducing agent. The diameter of graphene quantum dots was approximately 6 nm, applied as the hole transport layer in organic solar cell to improve the quantum efficiency of solar cells. GQDs were very friendly with environment, made at low temperatures and might be dried into powder form and dissolved well in polar solvents. Graphene quantum dots with a 0D structure had the workfunction suistable for the conductive polymer which increased the short current (from 2.41 mA/cm2 to 4.38 mA/cm2 ) of polymer solar cells. They improved the performance significantly compared to conventional solar cells.
Maximizing the energy of surface wave and diminishing the effect of lateral inhomogenousness in the multichannel analysis of the surface wave (MASW)
Multichannel analysis of surface wave (MASW) is one of the novel seismic methods in geophysic field in Vietnam. MASW is able to survey the stiffness of the soil environment under the ground via the shear-wave velocity VS by analyzing the spectral image of surface wave. We did the 1D MASW survey upon the borehole belonged to the residential development project at district 2, Ho Chi Minh city with fixed receiver system, different source orientations and different source offsets. The spectral images of surface wave were combined to maximize the surface wave’s energy on the spectral image of surface wave to minimize the effect of lateral inhomogenousness and near - far source offsets. The data points were chosen on the phase curve on spectral image of surface wave for the inversion process to define shear wave velocity VS. The VS from MASW was compared to the petrographic components and another seismic method (downhole). The relative difference of the obtained VS values between two methods was less than 10%. The change of VS in MASW was absolutely compatible to petrographic components in geological borehole, near surface filled soil layer (93 m/s), dark-gray silty layer (68–157 m/s), sandy clay layer (250–265 m/s) and lower clay layer (254–400 m/s).
GPRTVN – Processing ground penetrating radar data software
Designing and mapping underground construction works have been doing for years to meet urgent demands in urbanization process. In this field, Ground Penetrating Radar (GPR) method has shown many advantages in determining underground structures. However, our country has almost no processing program that meets demands of processing and interpretation GPR data. This paper introduced GPRTVN processing program which was the research result of the Department of Geophysics for years. This program could process data of many present GPR equipments and quickly provide cross sections of existing underground constructions. It would be very useful for construction and building investigation companies in Vietnam.
Method for calculation the absolute dose in the Monte Carlo simulation
In this study, we presented the method for calculation the absolute dose in the Monte Carlo simulation following the prescription of Popescu et al for the 6 MV photon energy. The BEAMnrc was used to simulate 6 MV photon beams from a Siemens Primus M5497 linear accelerator at DongNai general hospital. The DOSXYZnrc was then used to calculate the dose distribution in a homogeneous phantom (in form of CT images). The absolute dose obtained from the MC and TPS were compared with measured ones using an ion chamber (Farmer Type Chamber FC65-P, IBA). The average doses discrepancy between the simulated and measured dose was 0.53±0.37% and between the simulated and TPS was 1.00±0.51%. Results showed good agreement between simulated, measured and calculated dosed on a homogeneous phantom.
Decolorization of textile dyes by TiO2 -based photocatalyst using polyol as electron donor
Decolorization of textile dyes including 2,6-dichlorophenolindophenol (DCIP), congo red (CR) and methyl orange (MO) by using TiO2-based photocatalyst in the presence of polyols such as glycerol and ethylene glycol was investigated. Polyols were used as sacrificial electron donors (SEDs). The results showed that the polyols improved the rate and yield of a light-induced decolorization of dyes in comparison with a photocatalytic reaction without polyols. A possible reaction mechanism of dye decolorization by the photocatalyst in the presence of electron donors was proposed. TiO2 photocatalyst absorbed light to generate electrons (e- ) and holes (h+ ). The electrons and holes were prevented from recombining by the presence of SEDs. The free electrons and holes then involved in decolorization processes through reduction or oxidation reactions. The effects of TiO2 catalyst amounts, irradiation time and polyol concentrations on dye decolorization were investigated. The decolorization efficiency significantly increased with the increasing irradiation time, SED concentrations and certain amounts of TiO2.
Chemical constituents of Euphorbia tirucalli L.
Euphorbia tirucalli has not been chemically studied much in Vietnam. This research described the isolation and elucidation of compounds isolated from the plant collected in Binh Thuan. Multiple chromatographic methods were applied, including normal phase silica gel column chromatography and thin-layer chromatography. Seven compounds were isolated and their chemical structures were elucidated by spectroscopic analysis as well as comparing their data with the ones in the literature. They are arjunolic acid (1), eriodictyol (2), quercitrin (3), afzelin (4), scopoletin (5), 3,3′,4- trimethylellagic acid (6), and gallic acid (7). Among them, compound 1 a major component was isolated for the first time in Euphorbia genus, while three compounds 2, 4, and 5 were isolated from this species for the first time.
Ionic liquid supported on magnetic nanoparticles (-Fe2O3@SiO2-IL-ZnxCly) as the green catalyst for the Paal-Knorr reaction
The ionic liquid supported on magnetic nanoparticles ( -Fe2O3@SiO2-IL-ZnxCly) was found to be an effective catalyst for the Paal–Knorr reaction. The condensation of aromatic amine and acetonylacetone under solvent-free sonication afforded the desired pyrrole derivatives in high yields. The pyrrole derivatives was isolated in yield with a environmentally friendly process. The structure of products was determined by modern methods such as nuclear magnetic resonance spectroscopy (1H and 13C NMR), high resolution mass spectrometry (HR-ESI-MS) or gas chromatography-mass spectrometry (GS-MS). Moreover, the catalyst could be easily recovered by magnetic separation and reused for five times without significant loss of the catalytic activity.
Chemical constituents of the lichen Roccella sinensis growing in Binh Thuan province
The lichen Roccella sinensis has not been studied chemically. This research described the isolation and elucidation of compounds isolated from the lichen Roccella sinensis collected in Binh Thuan. Phytochemistry investigation of this lichen was carried out by using normal phase silica gel column chromatography and thin-layer chromatography. Six compounds was isolated. Their structures were established by extensively spectroscopic analysis as well as comparison with NMR data in the literatures. They are (+)-D-montagnetol (1), (+)-D-erythrin (2), lecanorin (3), 1-acetylerythritol (4), (E)-nostodione A (5), and 2,4-dihydroxyphthalide (6). This is the first time compounds 3 6 were found in the Roccella genus. Compounds 1, 2, and 6 were evaluated for their cytotoxic activities against HepG2 (liver hepatocellular carcinoma), NCI-H460 (human lung cancer), MCF-7 (human breast cancer), and HeLa (human epithelial cancer) and all of them showed no activity.
Chemical constituents of the propolis from the stingless bee Trigona minor
Propolis is a natural product produced by bees, and it is a mixture of resins and other bee excretions. The chemical composition of each type of propolis and its associated bioactivities also depend on the geographical regions, its food and the bee species. In Vietnam, propolis has been used in traditional medicine as the remedy to improve health and prevent diseases. From the ethanolic extract of the stingless bee propolis Trigona minor (Meliponini, Apidae), four lignan compounds were isolated. Their chemical structures were determined as (+)-isolariciresinol (1), 5-methoxy-(+)- isolariciresinol (2), (+)-lyoniresinol (3), and 6-(4- hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0] octan-2-one (4) by spectroscopic methods as well as comparing with data in the literature. Among them, compound 4 was the first isolated from natural sources, while others were isolated for the first time from this stingless bee propolis.
Physio-chemical properties and dynamic of the surface sediment in riparian mangroves along the Tien river, Tien Giang province
This study was conducted to investigate the physio-chemical properties and vertical dynamic of the surface sediment (0–5 cm) in riparian mangroves along the Tien river, Tien Giang province. The distribution of riparian mangroves located from the polyhaline zone (transect S1 and S2) to the mesohaline zone (transect S3 and S4) and the oligohaline zone (transect S5). Three plots (10x10 m) per transect were set based on the elevation of the mangrove floor (cm + mean sea level) and dominant plants. A total of 28 sediment samples were collected in December 2016 and April 2017. Seasonal variation of pH, redox potential (Eh), electrical conductivity of saturated extract (ECse), bulk density, sediment organic matter (SOM) and total sulfur (TS) were measured in accordance with the standard protocols. Seasonal trends of vertical erosion and accumulation were tested by the tracer stick method. The ECse values and TS concentrations were higher in the dry season and in transects closed to the estuary (S1, S2 and S3) but these trends weren’t found for pH, Eh, and SOM. In most of the riparian mangroves along the Tiền river, low elevation (0–50 cm) was one of important factors affecting the Eh and ECse. In the rainy season, major changes in vertical erosion and acumulation have occurred in the transects near the mouth of the river.
The development of rs7107217 genotyping method and initial study of the association of this gene with the breast cancer risk in Vietnamese women
Breast cancer is the most common cancer for women around the world. The presence of single nucleotide polymorphisms (SNP) on or near the coding region of breast cancer susceptibility genes can affect the regulation of gene expression, which may increase or decrease the risk of breast cancer. BARX2 was showed to stimulate the expression of ERS1, which involved in the development of breast cancer. SNP rs7107217 on 152kb downstream of the BARX2 could affect the level of protein BARX2 and had been proved to associate with the breast cancer risk in populations similar to Vietnamese, including Chinese and Korean. In this study, rs7107217 was genotyped and initially detemined the association with the breast cancer risk in Vietnamese. Real-time PCR HRM was optimized and used to genotype rs7107217 in 117 breast cancer cases and 105 healthy controls. Thereafter, the correlation of this SNP with the risk of breast cancer was initially determined by analyzing the differences in allelic and genotypic frequencies between cases and control groups. The results showed the optimal rs7107217 genotyping condition was successfully developed with the high sensitivity, specificity, and consistency. SNP rs7107217 had high polymorphism with the frequency of minor allele C of 29.9% and 35.3% in case and control, respectively. SNP rs7107217 had been found no association with the breast cancer risk (C vs A: P = 0.23, OR (95% CI) = 0.79 (0.53 – 1.17)). However with the low reliability of the analysis (11.71%) and the high potential related to the formation of breast cancer, the association between rs7107217 and breast cancer risk in Vietnamese population should be further conducted on a larger sample size to get higher accuracy.
The food composition in the Scylla paramamosain's stomach growing in the mangrove forest and industrial farming at Can Gio district, Ho Chi Minh City
Mud crab (Scylla paramamosain) farming is widely developed in Can Gio, however the economic value is not so high because buyers always prefer the crabs which are caught in the mangrove. The hypothesis is that whether there are differences in the food composition between two crab types (farming and mangrove) or not. So, the research was conducted at Can Gio mangrove forest to analyze the stomach content of S. paramamosain. The results were the food ingredients in S. paramamosain in Can Gio including snail shells, crab shells, animal materials, leaves, sand and unidentified materials. The snail shells, animal materials and leaves were dominant food on mangrove Scylla crab’s stomach. Meanwhile, the crab shells, animal materials and sand were main foods in the farming Scylla crab’s stomach. Leaves was the new food composition recorded in S. paramamosain stomach compared to previous studies. The result initially showed that the food composition affected the quality of Scylla paramamosain growing in Can Gio mangrove forest.
Biological activities of the liverwort Marchantia polymorpha L. collected at Da Lat, Lam Dong province
Marchantia polymorpha L. is used as a folk medicine in India, China and some European countries for the treatment of inflammation, cure cuts, wounds, diuretics, etc. Natural compounds and biological activities of this liverwort have been studied in the world for few years. At present time, the studies on bryophytes (non-vascular plants) are quite limited, especially in Vietnam. Therefore, this research focused on investigating some biological activities and analyzing of major secondary metabolites of M. polymorpha L. collected at Da Lat, Lam Dong. Among four extracted fractions (nhexane, chloroform, ethyl acetate and ethanol), the chloroform extract exhibited the best antioxidant, antibacterial, anti-proliferation of MCF-7 cell line activities. The ethyl acetate extract exhibited better activity of tyrosinase and α-glucosidase inhibition than others. Main secondary compounds in this species were phenolics, steroids and glycosidederivatives. These results were scientific evidences that might help us to understand rigorously about the ultilization of Marchantia liverwort in the traditional treatment and new potential applications in the contemporary medicine.
The presence of cellulose-degrading microorganisms in Perisesarma eumolpe crab’s stomach at opened areas of Can Gio mangrove forest
The study was conducted to determine the presence of cellulose-degrading microorganisms which were living in the stomach of Perisesarma eumolpe crabs. P. eumolpe were collected in the gap of Can Gio mangrove caused by Durian typhoon in 2006. The study identified 520 microorganism samples from 30 stomach samples Cellulose degrading microbacteria were isolated on three types of nutrient media: meat extract – peptone, Gause and Czapek – Dok with CMC. These 520 microbial samples included of 496 aerobic bacteria, 7 actinomycetes and 0 mold samples. The number of cellulose degrading microorganisms was also accounted for 46% of total (240 samples). Among these, there were 24 bacteria strains and 5 actinomycetes strains which degradated cellulose based on the difference in the colony and the cell shape. The average microbial density per crab gut was approximately 0.66 ×105 to 6.6 ×105 cell/mL. In addition, the results showed that cellulose degrading microorganism groups have importantly contributed to the food sources for P. eumolpe during their living in the mangrove forest.
Seasonal composition and abundance of zooplankton in snakehead fish ponds at Ham Giang commune, Tra Cu district, Tra Vinh province
These zooplankton samples and water samples were taken at 4 sites in the fish pond area (2 outside points in the river and 2 inside point in the fish pond). The results were recorded 76 zooplankton taxa which were belong to 28 genuses and 3 phylums (Protozoa, Rotifera and Arthropoda: Cladocera, Copepoda, Ostracoda). The Rotatoria phylum was dominated over 70% of species composition and 45% of individual density. The zooplankton communities in the outside were more diverse than those in the fish ponds. Besides, there was a significant difference between the individual density of the inside and outside ponds. The Shannon-Wiener diversity index showed that the water qualities were from lightly to moderately polluted at all points. Water of inside pond was polluted by organic materials, with the dominated by Brachionus genus. The Bray – Curtis similarity showed that the difference between zooplankton communities of inside and outside ponds was about 40%. Therefore, the fish pond water could affect natural water sources.
Dissecting lipid accumulation of microalgae Nannochloropsis oculata using fluorescent image analysis
Cell suspension of Nannochloropsis oculata was cultured in a modified f/2 medium to study the changes of lipid content during phases of growth. The growth of cell suspension was determined by measuring the cell density and diameter under light microscope. To observe and evaluate the accumulation of lipid droplets in microalgae cells, lipid droplets were stained with Nile Red fluorescent dye then examined under fluorescence microscope and the obtained images were analyzed using Fiji ImageJ, an image processing program. The cell density increased quickly at the first 6 days of culture while cell diameter reached the highest value at the 8th day and 20th day of culture. The presence of lipid droplets in the cells could be observed from the 20th day of culture. The size of lipid droplets was gradually increased after 60 days. Treatment of depleted nitrogen for 4 days resulted an increase in the accumulation of lipid. The intracellular lipid accumulation during phases of growth of the cell suspension under nitrogen-depleted conditions was also discussed.
Geochemical characteristics of Chu Lai body granitoids in Nui Thanh, Quang Nam
Chu Lai body granitoid typically had the gneiss structure. Petrography inclueded biotite and two-mica granitogneiss. The rock consisted of quartz (25 – 30%), plagioclase (28 – 30%), akaline feldspar (30 – 32%), biotite (7 – 8%) and musscovite (3 – 5%). Accessory minerals were zircone, apatite, garnet, etc. Geochemical characteristics were typically high SiO2 (73.89 – 74.38 wt%); high total amount of alkali (Na2O + K2O ̴ 8.28 – 8.89%). Aluminous saturation indexs - ASI (Al2O3/CaO + Na2O + K2O) are more than 1. They have enrichment of the lipthophile elements with high Cs, Rb and Pb indexs; negative anomalies were Nb, Ta and strong Eu, specially. Eu/Eu* values were very low (0.041 – 0.056). The petrographic and geochemical charecteristics showed that Chu Lai rocks were S-granite, formed during the collision tectonic between Indochina and South China block in the early Paleozoic.
Assessing the middle – upper pleistocene aquifer vulnerability due to the seawater intrusion in Ca Mau peninsula
The impact of climate change and over exploitation reduced the quality and groundwater reserves of the Ca Mau peninsula. This study used the GALDIT index to assess the vulnerability of groundwater resources due to salinity intrusion under exploitation and sea level rise. The GALDIT index results showed that the damage caused by the salinity intrusion of the Middle - Upper Pleistocene aquifer (qp2-3)was from moderate to high. The most vulnerable areas were Ca Mau and Soc Trang, accounting for 54.52% of the studied area, the average vulnerabbe areas were Kien Giang and Bac Lieu. This result could be used as a basis for policy planning, exploitation and utilization of sustainable groundwater resources, and to develop appropriate recommendations for people in the studied area.
Assessing the wastewater generation in the south of Binh Duong province
This study aimed to evaluate the wastewater generation in the south of Binh Duong province (including Di An, Thuan An, Tan Uyen, Ben Cat districts and Thu Dau Mot city) where is many development activities were undertaken as well as the risk of water pollution. By survey, data collection, and GIS, main pollutant loads (BOD, COD, SS, total N and total P) generated from main waste sources (domestic, industry, and livestock) were estimated and forecasted until 2030. The results showed that the amount of pollutant load in 2016 was about 105,273.6 ton/year, most of which came from domestic wastewater (about 60%). Di An and Thuan An districts generated the highest pollutant load in the study area, corresponding to 5.4 ton/ha.year and 2.8 ton/ ha.year. COD and BOD occupied a high proportion of pollutant parameters, which were 0.5 ton/ha.year and 0.26 ton/ha.year, respectively. To estimate the pollutant load in the future, two wastewater treatment scenarios were taken into the consideration: as similar as the current status (KB H) and according to A standard (KB A). By 2025, the total pollutant load would increase 2.1 times for KB H and 1.2 times for KB A. The corresponding figures for 2030 would be 3.1 and 2.0 times, respectively, indicating many pressures on the water quality. Accordingly, it is necessary to continue studying and evaluating the capacity of water sources for receiving wastewater, to the create basis for water quality management in particular and environmental management in general.
U-Pb zircon and Hf composition of granite Song Ma block
The granite of the Song Ma block mainly consists of two types of granite: biotite granite and hornblende-biotite granite. Biotite granites have the percent of plagioclase (35–45%), K-feldspar (25–35%), quartz (~20%) and biotite (~10%). Biotite-hornblende granite with the content of plagioclase (40–50%), K-feldspar (10–15%), hornblende (5–10%) and biotite (5%). Zircon crystals were selected from the granite of Song Ma block are V0741, V0856 and V1006 samples with the LA-ICP-MS U-Pb analyses gave concordant ages concentrated at 257±4Ma, 262±3Ma and 241±6Ma (weighted mean). Those ages are older than the results of the previous research. The mineral assemblages and geochemical characteristics show the typical of I-type granites. The results of Hf isotope composition analysis give the value of εHf(t) from +7.3 to +13.9, which is proven the sources of the granite Song Ma block similar to the granite of Phan Si Pan zone, NW Viet Nam during the period from late Permian to early Triassic.
Establishing vulnerability indicators to inundation in the context of the climate change
Flooding is a concern phenomenon, especially in the context of climate change (CC) and sea level rise. This work aimed to establish indicators used to assess vulnerability (V) due to inundation on the basis of considering the exposure (E), sensitivity (S) and adaptive capacity (AC) of a system. By literature review, data analysis, and expert methods, 33 indicators for assessing vulnerability due to inundation were established, including 4 E, 11 S (divided into 4 groups: society, economic, environment, and land use), and 18 AC indicators (divided into 4 groups: human, financial, infrastructure, and society). This work resulted in an important basis for comprehensive evaluation of vulnerability due to inundation in the context of CC and proposing suitable solutions.