Red River Delta Research Articles

Iron mineral transformations and their impact on As (im)mobilization at redox interfaces in As-contaminated aquifers

Iron minerals are the most important arsenic host in As-contaminated deltaic sediments. Arsenic release from Fe minerals to groundwater exposes millions of people worldwide to a severe health threat. To understand the coupling of Fe mineralogy with As (im)mobilization dynamics, we analyzed the geochemistry and mineralogy of a 46 m long sediment core drilled into the redox transition zone where a high As Holocene aquifer is juxtaposed to a low As Pleistocene aquifer in the Red River delta, Vietnam. We specifically concentrated on mm- to cm-scale redox interfaces within the sandy aquifer. Various Fe phases, such as Fe- and Mn- bearing carbonates, pyrite, magnetite, hematite and Fe-hydroxides (goethite, lepidocrocite) with distinct As concentrations were identified by a combination of high-resolution microscopic, magnetic and spectroscopic methods. The concentration of As and its redox species in the different Fe-minerals were quantified by microprobe analysis and synchrotron X-ray absorption. We developed a conceptual model integrating Fe-mineral transformations and related As (im)mobilization across the redox interfaces. Accordingly, As is first mobilized via the methanogenic dissolution of Fe(III) (oxyhydr)oxide mineral coatings on sand grains when reducing groundwater from the Holocene aquifer intruded into the Pleistocene sands. This stage is followed by the formation of secondary Fe(II)-containing precipitates (mainly Fe- and Mn-bearing carbonates with relatively low As < 70 μg/g), and minor pyrite (with high As up to 5800 μg/g). Due to small-scale changing redox conditions these Fe(II) minerals dissolve again and the oxidative behavior of residual Fe(III)-phases in contact with the reducing water leads to the formation of abundant Fe(III)/Fe(II) (oxyhydr)oxides especially at the studied redox interfaces. Microcrystalline coatings and cementations of goethite, magnetite and hematite have intermediate to high As sorption capacity (As up to 270 μg/g) creating a key sorbent responsible for As (im)mobilization at interfingering redox fronts. Our observations suggest a dynamic system at the redox interfaces with coupled redox reactions of abiotic and biotic origin on a mm to cm-scale. In a final stage, further reduction creates magnetite with low As sorption capacity as important secondary Fe-mineral remaining in reduced gray Pleistocene aquifer sands while considerable Fe and As is released into the groundwater. The presented redox-dependent sequence of Fe phases at redox interfaces provides new insights of their role in As (im)mobilization in reducing aquifers of south and southeast Asia.

Landholdings, livelihood choices and household income in the Red River Delta, Vietnam

ABSTRACT Land scarcity has frequently been cited as the primary barrier preventing rural households from pursuing better livelihoods in Vietnam and other developing societies. In this paper, we investigate the role of landlessness and landholdings in the choice of livelihoods and in household income in the Red River Delta, the most densely populated region in Vietnam. Using data from the 2018 Vietnam Household Living Standard Survey, our cluster analysis classifies five livelihoods pursued by local households, namely informal wage-earning jobs, formal wage-earning jobs, nonfarm self-employment, agriculture, and non-labor livelihoods. Non-laboring, agricultural, or informal wage-earning households earn less per capita income on average than formal wage-earning or nonfarm self-employment households, according to both descriptive and inferential statistical analyses. Our regression analysis demonstrates that land scarcity is not a significant obstacle preventing rural people from seeking gainful livelihoods in the region. The finding suggests that improving education and supporting non-farm activities should be high-priority government policies for local households with limited land and education. Such policies are expected to help them not only transform their livelihoods but also improve their economic well-being.

Predicting as Contamination Risk in Red River Delta Using Machine Learning Algorithms

Excessive presence of As level in groundwater is a major health problem worldwide. Additionally, several million residents of Red River Delta in Vietnam possess high risk of chronic As poisoning. As releases into groundwater due to natural process through microbially-driven reductive dissolution of Fe (III) oxides. The As-contained groundwater has been extracted by Red River residents using private tube wells for drinking and daily purposes. This leads to a necessity to generate a predictive model to assess the As risk of the studied wells. Four machine learning algorithms were used to predict the As probability of study sites in Red River Delta, Vietnam. The GBM was the best performing model with the accuracy, precision, sensitivity, and specificity of 98.7%, 100%, 95.2%, and 100%, respectively. In addition, it resulted the highest AUC of 92% and 96% for the PRC and ROC curves, with Eh and Fe as the most important variables. The partial dependence plot of As concentration on the model parameters showed that the probability of high level of As is related to the low number of wells’ depth, Eh, and SO4, along with high PO4 3− and NH4 +. This condition triggers the reductive dissolution of iron phases, thus releasing As into groundwater.

Attraction of foreign direct investment in agriculture

Agriculture is an industry with potential and advantages for development, but it is increasingly difficult to attract foreign direct investment (FDI) flows. Up to now, the results of attracting FDI inflows into the agricultural sector have many limitations, not really reaching the industry’s potential. This study will assess the current situation of attracting foreign direct investments into the agricultural sector in Vietnam in terms of FDI capital scale, FDI capital structure based on agriculture standard, investment method, investment partners and by investment recipients. The Red River Delta is one of the two Vietnamese economic regions with highly agricultural production. With the tradition of agricultural production and many favorable natural, economic and social conditions, the Red River Delta can further develop into a major agricultural production area of the country, contributing to economic development of the region and the whole country. However, FDI investment in agriculture in the region is modest compared to the potential of the industry as well as compared to other sectors in the region. While FDI inflow into Vietnam and other sectors in the region tends to increase strongly, FDI into agriculture is very low and has not grown for a long time, which is contrary to the trend of FDI to other sectors of the Red River Delta as well as the whole country and also contrary to the FDI flows to global agriculture.

Late Pleistocene-Holocene sedimentary evolution in the coastal zone of the Red River Delta

The Red River Delta is considered one of the largest megadelta systems in Asia. The formation of this delta has been controlled by the continent-ocean interaction and sea-level fluctuation during the Cenozoic. In this study, we present a new sequence stratigraphic framework of the Red River Delta based on borehole lithofacies analysis and high resolution seismic data. The Late Pleistocene–Holocene sediments in the coastal zone of the Red River Delta were subdivided into three systems tracts: (1) the lowstand systems tract (LST) is characterized by a Late Pleistocene alluvial silty sand facies complex (arLSTQ13b); (2) the transgressive systems tract (TST) is illustrated by the coastal marsh facies complex and the lagoonal greenish-gray clay facies of Early-Middle Holocene (amt, mtTSTQ21−2); and (3) the highstand systems tract (HST) is composed of the Middle-Late Holocene deltaic clayish silt facies complex (amhHSTQ22−3). The boundaries between these three systems tracts are not isochronous, namely: (1) The LST-HST boundary has been associated with the Würm 2 Glaciation, which occurred at ~40-18 Ka.; (2) The TST-LST boundary is identified by a transgressive erosion surface, whose age ranges from ~12-5 Ka.; and (3) the HST-TST boundary is an unconformity between the submarine deltaic facies complex and the Middle Holocene marine flooding plain.

Sediment budget and morphological change in the Red River Delta under increasing human interferences

The Red River sediment dispersal system has been increasingly altered by human activities, but the resultant morphodynamic change and sediment budget in the Red River Delta (RRD) has been little studied in a holistic perspective. In this study, time-series analysis of river water and sediment discharges from 1960 to 2010 was carried out to trace human interferences on sediment routing processes, and historical charts from 1930 to 2008 were digitized to reconstruct the Digital Elevation Models for investigating spatiotemporal variations in the RRD morphology and calculating their depositional and erosional fluxes. The results show that sediment reduction by 61.3% in the Red River is mainly induced by constructing the Hoa Binh Dam at the lower reach of the Da river, and deforestation and other land-use change have recently increased significantly the sediment loads in the Thao and Lo rivers. Intertidal and subtidal morphological changes in the RRD are highly site-specific in response to natural and anthropogenic drivers. Rapid intertidal accretion majorly occurs near the distributary mouths because of abundant sediment supply and artificially promoted siltation by land reclamation projects, but severe coastal erosion may occur secularly after the distributary outlet shifting or temporarily by storm events. The subaqueous RRD is generally featured by the contour-parallel zonation of erosion and accretion determined by strong longshore currents associated with monsoon winds. Net accretion was observed in the tide-dominated northern subaqueous RRD and has recently changed into a slight erosion due to reduced sediment input in the last two decades, while net erosion was monitored in the southern subaqueous RRD predominated by wave and longshore currents and has recently entered into a slight accretion phase in response to the distributary outlet shifting and secular morphodynamic adjustment. The study RRD region received on average 41.1 Mt./yr (Mt = 106 t) of suspended sediments, and 14.2 Mt./yr and 28.6 Mt./yr were estimated to accumulate on the intertidal flats and in the northern subaqueous RRD, respectively. However, erosion in the southern subaqueous RRD could contribute 42.9 Mt./yr of sediment to the system. Therefore, 41.2 Mt./yr of suspended sediment was indicated to escape from the study RRD region and transport further southward by longshore current to form the distal muddy clinoform along the inner Vietnam shelf. This sediment budget estimation should bear a significant uncertainty, but provides important information for multi-decadal sediment dispersal in a mega-delta system and coastal management.

Effective Removal of Arsenic in Drinking Water Using Facile Synthesized Fe2O3 Coated N-Doped TiO2 Nanoparticles

Arsenic contamination of water in the Red River and Mekong deltas brings the largest mass poisoning calamity in human history because drinking of arsenic contaminated water can cause cancers of the skin, lungs, bladder and kidney and other harmful diseases. In general, the arsenic exists in difference oxidation states such as –3, 0, +3, and +5, among which As(+3) has been considered as the most dangerous contaminant in the water. Synthesis of nature friendly and low cost, portable, and effective adsorbent for removal of arsenic in contaminated water is very essential for many countries where development of large industrial setup is difficult. In this work, we introduce a facile method for preparation of Iron Oxide (Fe2O3) coated N-doped Titanium Oxide (TiO2) nanoparticles (FNT NPs) towards effective removal of As(III) from drinking water. The FNT NPs were synthesized by a scalable low temperature, solution based hydrothermal method using as Iron(III) chloride (FeCl3), and N‑doped TiO2 NPs as starting materials. The prepared FNT NPs were characterized by Scanning electron microscopy (SEM), Energy-Dispersive X-Ray (EDS), and Transmission electron microscopy (TEM), whereas the As(III) adsorption studied were done using Inductively coupled plasma mass spectrometry (ICP) analysis. Results pointed out that the high quality FNT NPs were successfully synthesized by a low temperature hydrothermal method with uniform size and shape. The adsorption test confirmed that the prepared FNT NPs can effectively remove the As from the water. The results shows 99.34% As(III) form water was adsorbed using the prepared FNT NPs within 60 min. The results shows synthesized FNT NPs, could provide large specific surface area for effective adsorption sites for capturing and removal of As(III) in the water.

Development of 2015 Vietnam emission inventory for power generation units

The 2010 and 2015 Emission Inventories (EIs) for Vietnam Thermal Power Plants (TPP) were concurrently developed using the bottom-up approach. Local activity data, emission factors, and pollution control efficiencies were applied to estimate the annual emissions of individual power plants. As the EIs consider all emission control activities with relevant unit upgrades, the estimated SO2, NOx and PM species were found to be lower than most of the reported EIs by 20–70%. An overestimation (i.e., 3.8 times) of SO2 has been observed in Emission Database for Global Atmospheric Research (EDGAR) EI, which can possibly be attributed to the assumption of no air pollution controls in their inventory. Overall, the newly developed EIs indicate that the annual emissions of coal-fired TPPs were highest among the various types of TPPs, and the largest uncertainty occurred in NOx with ranges between −23% and +31%. In terms of regional distribution, the most significant emission sources of CO2, N2O, SO2, NOx, PM10, PM2.5, BC, and OC were from the Red River Delta region resulted from coal-fired TPPs, while the Southeast region had the largest sources of CO, NMVOC, and CH4 caused by gas-fired TPPs. The study reveals that from 2010 to 2015, the growths of NOx, CO, NMVOC, PM10, PM2.5, BC, OC, CO2, CH4, and N2O emissions were 51%, 39%, 41%, 109%, 88%, 9%, 107%, 58%, 33%, and 119%, respectively, while ~19% reduction in SO2 was found resulted from the decommission of oil-fired TPPs.

Survey-based inventory for atmospheric emissions from residential combustion in Vietnam.

Local questionnaire surveys were conducted to collect representative activity data for calculation of annual emissions from residential combustion in Red River Delta (RRD), Vietnam, for 2010-2015. Multistage statistical sampling was implemented in the surveys for Hanoi Metropolitan Region (HMR) and deep rural area of Ninh Binh province (Con Thoi, Ninh Binh (CTNB)). Emission factors were scrutinized to select relevant ranges and central values for typical cookstoves in RRD. Large differences in the activity data (cooking activities, fuel-stove types, and fuel consumption) were found between three HMR strata (urban, suburban, and rural populations) and CTNB, respectively, which resulted in distinctly different annual emissions per capita. Annual 2010 emissions from residential combustion in RRD were estimated for toxic pollutants, in Gg/year, of 217 for CO, 1.5 NOx, 7.4 SO2, 33 NMVOC, 3.7 NH3, 16.9 PM2.5, 1.4 BC, and 7.1 OC, along with 171t/year of total PAHs with 0.7t/year of BaP, and greenhouse gases of 5395 CO2, 17.2 CH4, and 0.7 N2OGg/year. Emissions increased by 1.5-7.8%, varying with species, over the 6-year period. Prevalent use of crop residue in CTNB induced its dominant shares in the residential combustion emissions not only in this deep rural area but also in the entire RRD domain. Spatial emission distribution exhibited high intensities over districts having high rural population density. Global warming potential results indicated the dominant role of black carbon, especially over the 20-year horizon. Switching from solid fuels to liquefied petroleum gaswould reduce the emissions from this sector and bring in multiple benefits.

Antibiotic and antiparasitic residues in surface water of urban rivers in the Red River Delta (Hanoi, Vietnam): concentrations, profiles, source estimation, and risk assessment.

Antibiotic residues and antimicrobial resistance in surface water are issues of global concern, especially in developing countries. In this study, the occurrence of seven antibiotics and one antiparasitic agent was determined in surface water samples collected from four rivers running through Hanoi urban area in the Red River Delta, northern Vietnam. The pharmaceuticals in water samples were analyzed by solid-phase extraction combined with liquid chromatography-tandem mass spectrometry method. The concentrations of pharmaceuticals in our samples ranged from 3050 to 16,700 (median 7800) ng/L, which were generally higher than levels found in river water from many other locations in the world. Amoxicillin, oxfendazole, and lincomycin were the most dominant and frequently detected compounds (detection rate 100%), which together accounted for 76 ± 14% of total concentrations. Sulfacetamide and sulfamethoxazole were detected at moderate concentrations in more than two-thirds of the analyzed samples. The remaining antibiotics (i.e., azithromycin, ciprofloxacin, and ofloxacin) were found at lower detection frequency and concentrations. Antibiotic concentrations in the water samples were not significantly different between the investigated rivers. Meanwhile, levels of pharmaceuticals in the samples collected in February 2020 were higher than those found in the remaining samples, largely due to the sharp decrease in sulfamethoxazole and azithromycin concentrations of the samples collected in March and April. Considerable ecological risks of antibiotics in surface water were estimated for some compounds such as amoxicillin, ciprofloxacin, and ofloxacin.

Evaluation of a facility-based inspection tool to assess lymphedema management services in Vietnam.

Assuring availability of services for patients with lymphedema is required for countries to be validated as having achieved elimination of lymphatic filariasis (LF). A direct inspection protocol (DIP) tool, designed to measure the readiness to provide quality lymphedema management services, has recently been developed. The DIP tool includes 14 indicators across six quality themes: trained staff, case management and education materials, water infrastructure, medicines and commodities, patient tracking system, and staff knowledge. We evaluated the use of the tool in Vietnam, where data were needed to inform validation efforts. To apply the tool in Vietnam, we compiled a list of 219 commune health stations (CHS) with known lymphedema patients and conducted a cross-sectional survey in 32 CHS; including 24 in Red River Delta region, 2 in the North Central region, and 6 in the South Central Coast region. The mean facility score, calculated by assigning 1 point per indicator, was 8.8 of 14 points (63%, range 4[29%]-13[93%]). Percentage of surveyed facilities with staff trained in last two years was 0%; availability of lymphedema management guidelines (56%); availability of information, education, and communication materials (16%); reliable improved water infrastructure (94%); availability of antiseptics (81%), antifungals (44%), analgesics or anti-inflammatories (97%), antibiotics (94%); supplies for lymphedema and acute attack management (100%); lymphedema patients recorded in last 12 months (9%); staff knowledge about lymphedema signs/symptoms (63%), lymphedema management strategies (72%), signs/symptoms of acute attacks (81%), and acute attack management strategies (75%). The tool allowed standardized assessment of readiness to provide quality services. Lack of trained health staff, limited patient tracking, and depletion of education materials were identified as challenges and addressed by the national program. Survey data were included in the validation dossier, providing evidence necessary for WHO to validate Vietnam as having eliminated lymphatic filariasis in 2018.

The Situation of Small and Medium Enterprise Development in Vietnam

In the period of 2010-2017, the number of small and medium enterprises (SMEs) of Vietnam tended to be increased, accounting for about 98% of the total number of Vietnamese enterprises by the end of December 2017. Vietnam's SMEs are mainly private enterprises operating in the field of commerce and services as well as industry and construction, mostly concentrated in the Southeast and the Red River Delta. In the research period, micro enterprises had experienced a sharp increase in the loss rate, making the loss rate of the whole enterprise soar. In addition, SMEs were increasingly dependent on loans and especially small businesses had less access to bank loans as well as deferred purchase. However, Fixed-charge coverage ratio of SMEs had been improved and the gap between large enterprises and small enterprises had been narrowed.

A descriptive survey of porcine epidemic diarrhea in pig populations in northern Vietnam.

Porcine epidemic diarrhea (PED) virus (PEDV) is a globally emerging and re-emerging epizootic swine virus that causes massive economic losses in the swine industry, with high mortality in piglets. In Vietnam, PED first emerged in 2009 and has now developed to an endemic stage. This is the first cross-sectional survey performed to evaluate the proportion of PEDV-positive swine farms in Vietnam from January 2018 to February 2019. Fecal samples from 327 pig farms in northern Vietnam were collected and tested for PEDV infection by reverse transcription-loop-mediated isothermal amplification (RT-LAMP) method. The proportion of PEDV-positive farms was 30.9% and PEDV-positive farms were distributed throughout the study area. The highest proportion of PEDV-positive farms was 70% (7/10) among nucleus production type farms (P < 0.05). Higher proportions of PEDV-positive farms were found in the Northeast and Red River Delta areas, which are the major areas of pig production (P < 0.05). The proportion of PEDV-positive farms was higher among larger farms (P < 0.05). Our findings illustrate the high proportion of PEDV-positive farms in the Vietnamese pig population and will help to better understand the epidemiological dynamics of PED infection, to estimate impact, and establish and improve prevention and control measures.Electronic supplementary materialThe online version of this article (10.1007/s11250-020-02416-1) contains supplementary material, which is available to authorized users.

Comparision of several secondary metabolite and elemental ion contents of leaves from &lt;i&gt; Kandelia obovata &lt;/i&gt; and &lt;i&gt; Sonneratia caseolaris &lt;/i&gt; forests located in the Red River delta

The two mangrove species Kandelia obovata and Sonneratia caseolaris were widely planted in the Red River delta. Both K. obovata and S. caseolaris forests play an important role in the economic development and environmental protection of the delta. However, chemical responses of the common mangrove forests to different ecological conditions in the delta have not yet been described. In this study, we evaluated chemical responses of K. obovata and S. caseolaris through comparisons of the content of metabolites and element ions in leaves of mangrove plants located under different ecological conditions in the Red River delta. In the low salinity area (Thuy Truong), specific leaf areas of K. obovata and S. caseolaris were much lower while the succulent index was higher compared to those in the high salinity area (Kim Trung). In Kim Trung, both species had a lower ratio of chlorophyll a/chlorophyll b. K. obvata in lower light (under the S. caseolaris canopy) had lower levels of chlorophyll b, resulting in a higher Chla/chlb ratio. There was no difference in the Mg content of leaves between two areas. An increase in Na content in leaves of mangrove plants in the higher salinity area was evident. The high K/Na ratio in leaves were eveluated for both species in high salinity areas. Our results also showed better uptake of K in leaves of S. caseolaris growing in the low salinity conditions (Thuy Truong), i.e. Thuy Truong has more favourable ecological conditions for S. caseolaris. Carotenoid contents in leaves of both species growing in the higher salinity were lower.

Potential use of satellite observations to detect suspended sediment in delta region: a case study of the Red river delta, Vietnam

Potential use of satellite observations to detect suspended sediment in delta region: a case study of the Red river delta, Vietnam

Nation-Scale Mapping of Coastal Aquaculture Ponds with Sentinel-1 SAR Data Using Google Earth Engine

Global rapid expansion of the coastal aquaculture industry has made great contributions to enhance food security, but has also caused a series of ecological and environmental issues. Sustainable management of coastal areas requires the explicit and efficient mapping of the spatial distribution of aquaculture ponds. In this study, a Google Earth Engine (GEE) application was developed for mapping coastal aquaculture ponds at a national scale with a novel classification scheme using Sentinel-1 time series data. Relevant indices used in the classification mainly include the water index, texture, and geometric metrics derived from radar backscatter, which were then used to segment and classify aquaculture ponds. Using this approach, we classified aquaculture ponds for the full extent of the coastal area in Vietnam with an overall accuracy of 90.16% (based on independent sample evaluation). The approach, enabling wall-to-wall mapping and area estimation, is essential to the efficient monitoring and management of aquaculture ponds. The classification results showed that aquaculture ponds are widely distributed in Vietnam’s coastal area and are concentrated in the Mekong River Delta and Red River delta (85.14% of the total area), which are facing the increasing collective risk of climate change (e.g., sea level rise and salinity intrusion). Further investigation of the classification results also provides significant insights into the stability and deliverability of the approach. The water index derived from annual median radar backscatter intensity was determined to be efficient at mapping water bodies, likely due to its strong response to water bodies regardless of weather. The geometric metrics considering the spatial variation of radar backscatter patterns were effective at distinguishing aquaculture ponds from other water bodies. The primary use of GEE in this approach makes it replicable and transferable by other users. Our approach lays a solid foundation for intelligent monitoring and management of coastal ecosystems.

A stochastic simulation model of African swine fever transmission in domestic pig farms in the Red River Delta region in Vietnam.

The main objectives of this study were to model various scenarios of African swine fever (ASF) virus transmission among farms in Vietnam and to evaluate the impact of control strategies using North American Animal Disease Spread Model (NAADSM). A total of 7,882 pig farms in the Red River Delta (RRD) region were obtained from the General Statistics Office, and then, random points corresponding to the number of farms in each province were generated as exact farm locations were not available. A total of 10 models were developed, including movement control scenarios. In addition, we conducted sensitivity analysis to assess the impact of indirect contact transmission probability (TP). Overall, the indirect contact exhibited an important role in transmitting the ASF virus. In order to minimize ASF transmission between farms, we found that movement restriction needed to reach a certain level (approximately between 50% and 75%) and that the restriction had to be applied in a timely manner. This study offers valuable insight into how ASF virus can be transmitted via direct and indirect contact and controlled among farms under the various simulation scenarios. Our results suggest that the enforcement of movement restriction was an effective control measure as soon as the outbreaks were reported. In addition, this study provided evidence that high standards of biosecurity can contribute to the reduction of disease spread.

The roles of social economic status and undernutrition in regional disparities of the under‐five mortality rate in Vietnam

From 2005 to 2017, the prevalence of mortality in Vietnamese children under five years old showed large regional disparities. In 2017, mortality in the wealthiest region was 12.6‰, whereas the most disadvantaged region it was three times as high, at 36‰. This study aims to identify factors affecting regional disparities of the under-five mortality rate (U5MR) in Vietnam. We applied Structural Equation Modelling to estimate the degree and the pathway through which undernutrition and socio-economic status (SES) contributed to the under-five mortality disparities. SES is estimated as a common latent factor of three socio-economic measures, that is, education, poverty and income. The direct effect of SES on U5MR is at 2.16 through the underweight pathway, which is 5 times higher than the effect of underweight on U5MR. Through the stunting channel, this direct impact is 1.43, nearly twice as high as the impact of the stunting rate. SES also has an indirect effect on U5MR through these undernutrition pathways. In total, we estimate that an increase in SES index will make the U5MR increase by 2.73‰. Among the three indicators of SES, poverty conveys the strongest signal of a considerable change in SES, thus to a subsequent change in U5MR. Among two types of undernutrition, the effect of stunting on U5MR is dominant, more than 3 times as high as that of underweight. These findings have important implications for socio-economic and health interventions: those that strongly focus on the reduction of regional poverty and stunting rates would be effective in bridging the regional gap in the U5MR in Vietnam.

Land subsidence and its effects on coastal erosion in the Nam Dinh Coast (Vietnam)

The Nam Dinh Coast is a constituent part of the dynamic coastline, belonging to the Red River Delta. It is bounded to the north and south by the Red and Day Rivers, with Ninh Co and So Rivers located in the middle. This coast has been undergoing severe erosion during the last hundred years. Over this period, vital agricultural area along the coastline has vanished into the sea and families have been forced to abandon their houses due to the erosive action of waves. Numerous studies were conducted to identify the major causes governing the erosion problems, and several hypotheses have been proposed. In the present work, remote sensing data analysis techniques with both optical and synthetic aperture radar (SAR) were employed to examine the hypothesis that land subsidence is contributing to the erosion along the Nam Dinh Coast. The results revealed that the high lateral erosion rates observed at sandy beaches between estuaries are approximately -6 m/yr in the south and -10 m/yr in the north of the So River. Meanwhile, sediments transported from the rivers accumulate mainly around the estuaries, leading to rapid accretions of approximately +93, +4, and +46 m/yr for Day, Ha Lan (So River), and Ba Lat (Red River), respectively. Simultaneously, land is sinking and uplifting at highly uneven rates, with a few sections subsiding 10 times faster than the overall spatial average. Uplifting observed in southern areas ranges from +1.2 to +1.9 mm/yr. In contrast, subsidence was identified in the northern parts, with mean rates varying from -0.1 to -12.3 mm/yr. Based on the Bruun Rule, the combined effects of land subsidence and relative sea level rise (SLR) could explain approximately 66% of the observed rate of erosion in the northern part of Ha Lan. Findings from surface deformation data contribute to a deeper insight into coastal erosion in Nam Dinh.

Dataset on the effects of spacing and fruit truss limitation on the growth, yield and quality of open-field tomato plants.

This article presents data on the effects of spacing and fruit truss limitation on tomato plant growth, yield and fruit quality. Plants with two, three, and four fruit trusses (T1-T3) were grown in four different spaces (S1-S4) to create 12 treatments. The experiment was conducted on an open field with a randomized complete block design and three replications. Data on fruit quantity, weight, and yield were collected to assess the effects of plant density and fruit truss limitation on tomato fruit produced and marketable fruit produced. This data could help develop a strategy for breeding new tomato cultivars for high density planting on the rice-based rotational crop systems in the Red River Delta of Vietnam and other similar sub-tropical regions.