Chemical characterization and source apportionment of ambient nanoparticles: a case study in Hanoi, Vietnam.

PM has been believed to have adverse short- and long-term effects on human health. However, the information of PM that is needed to fully evaluate its influence on human health and environment is still scarce in many developing countries. This is a comprehensive study on the levels, chemical compositions, and source apportionment of PM conducted in Hanoi, Vietnam.

Study loading capacties of air pollutant emissions for developing countries: a case of Ho Chi Minh City, Vietnam.

Ho Chi Minh City (HCMC) is one of the cities in developing countries where many concentrations of air pollutants exceeded the Vietnam national technical regulation in ambient air quality including TSP, NO, Ozone and CO. These high pollutant concentrations have destroyed the human health of people in HCMC. Many zones in HCMC can't receive more air pollutants.

Spatial and temporal variations of PAHs in surface sediments of estuarine and coast of CanGio wetland, Vietnam.

Surface sediments from estuarine and coast of CanGio wetland (CGW) of Hochiminh City, Vietnam, were investigated to identify the spatial and temporal variations of polycyclic aromatic hydrocarbons (PAHs). The total PAHs showed wide variation but similar to patterns observed (F = 0.901, p = 0.

Dramatic decrease of flood frequency in the Mekong Delta due to river-bed mining and dyke construction.

Here we present a proof of concept evaluation of the impacts of riverbed-mining on river-wetland connectivity by analyzing the temporal trends of the flood frequencies in the Vietnamese Mekong Delta (VMD), while accounting for the effect of dyke constructions. We focus on the Long Xuyen Quadrangle (LXQ), which is significant in terms of biodiversity and economic contribution to the VMD as it is one of the most important food baskets of Southeast Asia that depends on seasonal flooding. Our results indicate that the flood frequency in LXQ has decreased significantly over the past 20 years (1995-2015).

Sand mining in the Mekong Delta revisited - current scales of local sediment deficits.

The delta of the Mekong River in Vietnam has been heavily impacted by anthropogenic stresses in recent years, such as upstream dam construction and sand mining within the main and distributary channels, leading to riverbank and coastal erosion. Intensive bathymetric surveys, conducted within the Tien River branch during the dry and wet season 2018, reveal a high magnitude of sand mining activities. For the year 2018, an analysis of bathymetric maps and the local refilling processes leads to an estimated sand extraction volume of 4.

Cyanobacterial Blooms and Microcystins in Southern Vietnam.

Studies on cyanobacteria in Vietnam are limited and mainly restricted to large reservoirs. Cyanobacterial blooms in small water bodies may pose a health risk to local people. We sampled 17 water bodies in the vicinity of urban settlements throughout the Mekong basin and in southeast Vietnam.

Transgenerational effects of cyanobacterial toxins on a tropical micro-crustacean Daphnia lumholtzi across three generations.

Climate change and human activities induce an increased frequency and intensity of cyanobacterial blooms which could release toxins to aquatic ecosystems. Zooplankton communities belong to the first affected organisms, but in tropical freshwater ecosystems, this issue has yet been poorly investigated. We tested two questions (i) if the tropical Daphnia lumholtzi is capable to develop tolerance to an ecologically relevant concentration of purified microcystin-LR and microcystins from cyanobacterial extract transferable to F1 and F2 generations? And (ii) would F1 and F2 generations recover if reared in toxin-free medium? To answer these questions, we conducted two full factorial mutigenerational experiments, in which D.

Treatment of tapioca processing wastewater in a sequencing batch reactor: Mechanism of granule formation and performance.

The formation of aerobic granular sludge was carried out in a sequencing batch reactor (SBR) for tapioca processing wastewater treatment. The effect of organic loading rates (OLRs) in the range of 2.5-10.

The effect of food, light intensity and tank volume on resting eggs production in Daphnia carinata.

Sexual reproduction is an important stage of cyclical parthenogenesis Daphnia, these cyclic parthenogens need to time their shift from asexual to sexual reproduction correctly, based on environmental cues. We investigated the effect of food quality and quantity, light intensity, and culture tank volume on the resting eggs production of a tropical Daphnia carinata clone of Vietnam. The results showed that sexual ephippia production of the D.

Warming Affects Growth Rates and Microcystin Production in Tropical Bloom-Forming Microcystis Strains.

Warming climate is predicted to promote cyanobacterial blooms but the toxicity of cyanobacteria under global warming is less well studied. We tested the hypothesis that raising temperature may lead to increased growth rates but to decreased microcystin (MC) production in tropical strains. To this end, six strains were isolated from different water bodies in Southern Vietnam.

Analysis of antibiotic multi-resistant bacteria and resistance genes in the effluent of an intensive shrimp farm (Long An, Vietnam).

In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bacteria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam).

Development of a Procedure for Evaluating the Impacts of the Accidental Emission of Hazardous Chemicals, Case Study in Ho Chi Minh City, Vietnam.

The study aims at developing a process to evaluate the impacts of the accidental emission of hazardous chemicals. The proposed process consists of four basic steps: i) identifying risks/hazards; ii) development of the worst-case scenario; iii) simulating the emission and dispersion of the toxic chemicals; and iv) assessing the severity of the impact to the people and the surroundings. It makes use of different techniques including accidental release source term, atmospheric dispersion modeling and results in the concentration and extent of the toxic chemicals in the atmosphere for either the direct evaporation of toxic chemicals as a primary emission or the dispersion of toxic chemicals as a domino effect of a fire or explosion accident.

Fixed-bed column recirculation system for investigation of sorption and biodegradation of organic pollutants in saturated sediment: a detailed design and development.

Background: Sorption and biodegradation are the primary processes of organic pollution remediation in aquatic and soil/sediment environments. While researchers have substantially reported their findings regarding these processes, little attention has been given to description of experimental apparatus. This technical paper aims to present the development and detailed design of a fixed-bed column recirculation (FBCR) system which has been widely applied to investigate sorption and biodegradation of organic pollutants in aquatic and/or sediment environments.

Ecophysiological responses of young mangrove species Rhizophora apiculata (Blume) to different chromium contaminated environments.

Many mangrove forests have suffered from the contaminated environments near industrial areas. This study addresses the question how these environments influence the renewal of mangrove forests. To this end ecophysiological responses of the young mangrove species Rhizophora apiculata (Blume) grown under combinations of the factors heavy metals (here chromium), nutrition and soil/water environment were analyzed.

Sensitivity of a tropical micro-crustacean (Daphnia lumholtzi) to trace metals tested in natural water of the Mekong River.

Metal contamination is one of the major issues to the environment worldwide, yet it is poorly known how exposure to metals affects tropical species. We assessed the sensitivity of a tropical micro-crustacean Daphnia lumholtzi to three trace metals: copper (Cu), zinc (Zn) and nickel (Ni). Both, acute and chronic toxicity tests were conducted with metals dissolved in in situ water collected from two sites in the lower part of the Mekong River.

Modelling and prediction of air pollutant transport during the 2014 biomass burning and forest fires in peninsular Southeast Asia.

During the dry season, from November to April, agricultural biomass burning and forest fires especially from March to late April in mainland Southeast Asian countries of Myanmar, Thailand, Laos and Vietnam frequently cause severe particulate pollution not only in the local areas but also across the whole region and beyond due to the prevailing meteorological conditions. Recently, the BASE-ASIA (Biomass-burning Aerosols in South East Asia: Smoke Impact Assessment) and 7-SEAS (7-South-East Asian Studies) studies have provided detailed analysis and important understandings of the transport of pollutants, in particular, the aerosols and their characteristics across the region due to biomass burning in Southeast Asia (SEA). Following these studies, in this paper, we study the transport of particulate air pollution across the peninsular region of SEA and beyond during the March 2014 burning period using meteorological modelling approach and available ground-based and satellite measurements to ascertain the extent of the aerosol pollution and transport in the region of this particular event.

Copper toxicity and the influence of water quality of Dongnai River and Mekong River waters on copper bioavailability and toxicity to three tropical species.

The present study investigated copper (Cu) toxicity and the influence of water quality characteristics of Dongnai River and Mekong River (Vietnam) surface waters to three tropical species; Daphnia lumholtzi, Ceriodaphnia cornuta, and Danio rerio. The river waters had a range of water quality parameters that modify Cu bioavailability and toxicity. The range of total hardness, alkalinity, pH and dissolved organic carbon were 15-64 mg/L as CaCO3, 18-58 mg/L as CaCO3, 6.

Microorganisms in landfill bioreactors for accelerated stabilization of solid wastes.

Landfill bioreactors (LBRs) with management of leachate and biogas have presented numerous advantages such as accelerated stabilization of solid wastes, reduced amount of leachate, and in situ leachate treatment. Such advantages have minimized environmental risks, have allowed extension of the useful life of the landfill site, and have fostered cost reduction. LBRs of three types have been developed using both anaerobic and aerobic modes: anaerobic, aerobic, and hybrid.

Antibiotic contaminants in coastal wetlands from Vietnamese shrimp farming.

Background And Purpose: Shrimp culture has been expanded rapidly in recent years in coastal wetland zone of Vietnam due to favorable natural conditions. However, this industry has caused several negative impacts to the environment. One of the critical issues is the excessive application of antibiotics including human medicines.

Chronic effects of cyanobacterial toxins on Daphnia magna and their offspring.

The zooplankton grazer Daphnia magna endures living in water bodies up to moderate densities of cyanobacteria, such as Microcystis spp., known for producing toxic secondary metabolites. Although daphnids are affected via decreased food filtering, inhibition of digestive proteases and lethality, development of tolerance against cyanobacterial toxins has also been observed.

Dioxin contamination in soils of Southern Vietnam.

Dioxin is the common name for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and is abbreviated as PCDD/Fs. In the case of Southern Vietnam, is of high concern dioxin contamination in the areas affected by past-use chemical defoliants. Our study related to the zone considered as a "hot spot"--Bien Hoa Airbase and surrounding areas (Bien Hung Lake).

Operational strategies for thermophilic anaerobic digestion of organic fraction of municipal solid waste in continuously stirred tank reactors.

Three operational strategies to reduce inhibition due to ammonia during thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) rich in proteins were investigated. Feed was prepared by diluting SS-OFMSW (ratio of 1:4) with tap water or reactor process water with or without stripping ammonia. Three continuously stirred tank reactors were operated at 55 degrees C with 11.

Tropical ecotoxicity testing with Ceriodaphnia cornuta.

The Sai Gon-Dong Nai river system in southern Vietnam is of great social and economic importance yet receives a large amount of industrial, domestic, and agricultural discharges. Toxicity assessment has started to become an issue in Vietnam, and it is important to employ a test system that is appropriate for typical Vietnamese conditions with a species that is representative of the invertebrates living in its aquatic ecosystems. The aim of this study was to develop and to validate an ecotoxicity test with an autochthonous organism.