Photochemical Smog Modelling Using the Air Pollution Chemical Transport Model (TAPM-CTM) in Ho Chi Minh City,Vietnam

Environmental Modeling & Assessment - This paper describes the application of the air pollution model (TAPM-CTM) for photochemical airshed modelling in the Ho Chi Minh region. The model was...     

Measuring water resource use efficiency of the Dong Nai River Basin (Vietnam): an application of the two-stage data envelopment analysis (DEA)

Environment, Development and Sustainability - The recent growth of agriculture, industry and urban areas in Vietnam requires a large amount of water consumption as a production factor. This paper...     

Application of SWAT model to assess land use change and climate variability impacts on hydrology of Nam Rom Catchment in Northwestern Vietnam

Environment, Development and Sustainability - Land use and land cover (LULC) changes, climate variability and climate change (CC) contribute hydrological response in tropical catchments, but their...     

Climate change impacts on a large-scale erosion coast of Hai Hau district,Vietnam and the adaptation

Among the effects of global warming, sea level rise (SLR) and severe typhoons pose the greatest threat to the stability of human settlements along coastlines. Therefore, countermeasures must be developed to mitigate the influences of strong typhoons and persistent SLR for coastal protection. This study assesses climate change impacts on coastal erosion, especially in two projected SLR scenarios of RCP2.6 and RCP8.5. The results show that SLR and severe typhoons lead to the increase of coastal erosion, beach lowering and scour. Moreover, as in projected SLR scenarios, average waves in high tide can cause severe soil erosion at inner slopes and lead to dyke failure by 2060. The paper highlights the need for additional countermeasures to protect the coast of Hai Hau district against SLR and severe typhoons. Among the alternatives available for countering these threats, applying soil stabilization and soil improvement combined with geosynthetics are promising strategies for coastal structures. Hybrid structures can be used with earth reinforcement and soil improvement. Additionally, the paper emphasizes the importance of multiple protective adaptations, including geosynthetics and ecological engineering measures against climate change-induced severe erosion on the coast of Hai Hau district.     

Esterification of sugarcane bagasse by citric acid for Pb2+ adsorption: effect of different chemical pretreatment methods

In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb²⁺ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C₂H₅OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb²⁺ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb²⁺ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.

     

Status of water use and potential of rainwater harvesting for replacing centralized supply system in remote mountainous areas: a case study

Environmental Science and Pollution Research - The failure of the centralized water supply system forced XY community to become more dependent on uncertain and unstable water sources. The results...     

Development of a combined isotopic and mass-balance approach to determine dissolved organic carbon sources in eutrophic reservoirs

A combined mass-balance and stable isotope approach was set up to identify and quantify dissolved organic carbon (DOC) sources in a DOC-rich (9 mg L⁻¹) eutrophic reservoir located in Western France and used for drinking water supply (so-called Rophemel reservoir). The mass-balance approach consisted in measuring the flux of allochthonous DOC on a daily basis, and in comparing it with the effective (measured) DOC concentration of the reservoir. The isotopic approach consisted, for its part, in measuring the carbon isotope ratios (δ¹³C values) of both allochthonous and autochthonous DOC sources, and comparing these values with the δ¹³C values of the reservoir DOC. Results from both approaches were consistent pointing out for a DOC of 100% allochthonous origin. In particular, the δ¹³C values of the DOC recovered in the reservoir (−28.5 ± 0.2‰; n = 22) during the algal bloom season (May-September) showed no trace of an autochthonous contribution (δ¹³C in algae = −30.1 ± 0.3‰; n = 2) being indistinguishable from the δ¹³C values of allochthonous DOC from inflowing rivers (−28.6 ± 0.1‰; n = 8). These results demonstrate that eutrophication is not responsible for the high DOC concentrations observed in the Rophemel reservoir and that limiting eutrophication of this reservoir will not reduce the potential formation of disinfection by-products during water treatment. The methodology developed in this study based on a complementary isotopic and mass-balance approach provides a powerful tool, suitable to identify and quantify DOC sources in eutrophic, DOC-contaminated reservoirs.     

Seagrass (Posidonia oceanica) monitoring in western Mediterranean: implications for management and conservation

The seagrass Posidonia oceanica is extensively monitored in Mediterranean coastal waters and is an ideal candidate for an eco-regional assessment of the coastal ecosystem. The aim of this study is to evaluate the potential of P. oceanica as eco-regional indicator for its assessment at the scale of Mediterranean basin. For this purpose, regional and national P. oceanica monitoring programmes are identified, and their data and metadata are collected and compared in terms of objectives, strategies, sampling designs and sampling methods. The analysis identifies a number of issues concerning data quality, reliability and comparability. In particular, the adoption of different sampling designs and methods may introduce relevant errors when comparing data. The results of this study stress the necessity of carefully planning monitoring programmes. Moreover, it highlights that the adoption of a number of common tools would facilitate all Mediterranean monitoring activities and allows an optimisation of management efforts at an eco-regional scale.     

Comprehensive temperature monitoring in an in-vessel forced-aeration static-bed composting process

Comprehensive temperature monitoring was done in an in-vessel forced-aeration static-bed composting process using sewage sludge. The three layers that divided the compost pile horizontally showed different temperature distributions. The temperature of the top layer appeared not to be influenced by the ambient temperature. The temperature of the center area of the top layer was taken to be the representative temperature for evaluating composting start-up performance. The temperature of the bottom layer was strongly influenced by the ambient temperature, and the temperature of the center area of the bottom layer was taken to be the representative temperature for pathogen control as it was the minimum temperature in the reactor. Composting start-up performance was influenced by several factors when the ambient temperature was either below or above 20°C. When the ambient temperature was below 20°C, the time taken to reach 65°C (T ₆₅) was influenced by the temperature of inflowing air, but when the temperature was higher than 20°C, it was influenced by the ratio of sewage sludge to seed compost (F/S). T ₆₅ was least when F/S was 1–2. Received: January 9, 2001 / Accepted: October 10, 2001