PHAM KIM TRANG - Academia.edu (original) (raw)

Papers by PHAM KIM TRANG

Environmental pollution (Barking, Essex : 1987), Jan 26, 2018

Lead poisoning is considered a public health threat, particularly in developing countries. Health... more Lead poisoning is considered a public health threat, particularly in developing countries. Health problems from Pb exposure occur in many parts of the world, especially near Pb mines, Pb smelters, and used lead-acid battery (ULAB) recycling plants. In this study, we analyzed the urine metabolome of residents in a village located near a ULAB recycling facility to investigate the biological effects of Pb exposure (ULAB: n = 44, Reference: n = 51). Lasso linear regression models were moderately predictive of blood Pb levels, as evaluated by a training set (R = 0.813) and against an external test set (R = 0.647). In lasso logistic regression models, areas under receiver operating characteristic curves, as measured by 5-fold cross-validation (AUC = 0.871) and against an external test set (AUC = 0.917), indicated accurate classification of urine samples from the affected village and from a reference site. Ten candidate biomarkers identified at false discovery rates of <0.05 were associ...

Geochimica et Cosmochimica Acta, 2016

Aquifers on the Red River flood plain with burial ages ranging from 500 to 6000 years show, with ... more Aquifers on the Red River flood plain with burial ages ranging from 500 to 6000 years show, with increasing age, the following changes in solute concentrations; a decrease in arsenic, increase in Fe(II) and decreases in both pH, Ca and bicarbonate. These changes were interpreted in terms of a reaction network comprising the kinetics of organic carbon degradation, the reduction kinetics of As containing Fe-oxides, the sorption of arsenic, the kinetics of siderite precipitation and dissolution, as well as of the dissolution of CaCO 3. The arsenic released from the Fe-oxide is preferentially partitioned into the water phase, and partially sorbed, while the released Fe(II) is precipitated as siderite. The reaction network involved in arsenic mobilization was analyzed by 1-D reactive transport modeling. The results reveal complex interactions between the kinetics of organic matter degradation and the kinetics and thermodynamic energy released by Fe-oxide reduction. The energy released by Fe-oxide reduction is strongly pH dependent and both methanogenesis and carbonate precipitation and dissolution have important influences on the pH. Overall it is the rate of organic carbon degradation that determines the total electron flow. However, the kinetics of Fe-oxide reduction determines the distribution of this flow of electrons between methanogenesis, which is by far the main pathway, and Fe-oxide reduction. Modeling the groundwater arsenic content over a 6000 year period in a 20 m thick aquifer shows an increase in As during the first 1200 years where it reaches a maximum of about 600 μg/L. During this initial period the release of arsenic from Fe-oxides actually decreases but the adsorption of arsenic onto the sediment delays the build-up in the groundwater arsenic concentration. After 1200 years the groundwater arsenic content slowly decreases controlled both by desorption and continued further, but diminishing, release from Fe-oxide being reduced. After 6000 years the arsenic content has decreased to 33 μg/L. The modeling enables a quantitative description of how the aquifer properties, the reactivity of organic carbon and Fe-oxides, the number of sorption sites and the

Water Resources Research, 2016

Many aquifers that are highly contaminated by arsenic in South and Southeast Asia are in the floo... more Many aquifers that are highly contaminated by arsenic in South and Southeast Asia are in the floodplains of large river networks. Under natural conditions, these aquifers would discharge into nearby rivers; however, large‐scale groundwater pumping has reversed the flow in some areas so that rivers now recharge aquifers. At a field site near Hanoi Vietnam, we find river water recharging the aquifer becomes high in arsenic, reaching concentrations above 1000 µg/L, within the upper meter of recently (< ∼10 years) deposited riverbed sediments as it is drawn into a heavily pumped aquifer along the Red River. Groundwater arsenic concentrations in aquifers adjacent to the river are largely controlled by river geomorphology. High (>50 µg/L) aqueous arsenic concentrations are found in aquifer regions adjacent to zones where the river has recently deposited sediment and low arsenic concentrations are found in aquifer regions adjacent to erosional zones. High arsenic concentrations are e...

Environmental Research, 2015

Archives of environmental contamination and toxicology, 2014

Perchlorate (ClO4 (-)) and thiocyanate (SCN(-)) interfere with iodide (I(-)) uptake by the sodium... more Perchlorate (ClO4 (-)) and thiocyanate (SCN(-)) interfere with iodide (I(-)) uptake by the sodium/iodide symporter, and thereby these anions may affect the production of thyroid hormones (THs) in the thyroid gland. Although human exposure to perchlorate and thiocyanate has been studied in the United States and Europe, few investigations have been performed in Asian countries. In this study, we determined concentrations of perchlorate, thiocyanate, and iodide in 131 serum samples collected from 2 locations in Northern Vietnam, Bui Dau (BD; electrical and electronic waste [e-waste] recycling site) and Doung Quang (DQ; rural site) and examined the association between serum levels of these anions with levels of THs. The median concentrations of perchlorate, thiocyanate, and iodide detected in the serum of Vietnamese subjects were 0.104, 2020, and 3.11 ng mL(-1), respectively. Perchlorate levels were significantly greater in serum of the BD population (median 0.116 ng mL(-1)) than those ...

Science of The Total Environment, 2014

Geochimica et Cosmochimica Acta, 2014

Reviews on Environmental Health, 2010

In this review, we summarize the current knowledge on exposure, metabolism, and health effects of... more In this review, we summarize the current knowledge on exposure, metabolism, and health effects of arsenic (As) in residents from As-contaminated groundwater areas of Vietnam and Cambodia based on our findings from 2000 and other studies. The health effects of As in humans include severe gastrointestinal disorders, hepatic and renal failure, cardiovascular disturbances, skin pigmentation, hyperkeratosis, and cancers in the lung, bladder, liver, kidney, and skin. Arsenic contamination in groundwater is widely present at Vietnam and Cambodia and the highest As levels are frequently found in groundwater from Cambodia. Sand filter system can reduce As concentration in raw groundwater. The results of hair and urine analyses indicate that residents from these As-contaminated areas are exposed to As. In general, sex, age, body mass index, and As exposure level are significantly associated with As metabolism. Genetic polymorphisms in arsenic (+III) methyltransferase and glutathione-5-transferase isoforms may be influenced As metabolism and accumulation in a Vietnamese population. It is suggested oxidative DNA damage is caused by exposure to As in groundwater from residents in Cambodia. An epidemiologic study on an association of As exposure with human health effects is required in these areas.

Geochimica et Cosmochimica Acta, 2012

ABSTRACT Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goet... more ABSTRACT Three surface complexation models (SCMs) developed for, respectively, ferrihydrite, goethite and sorption data for a Pleistocene oxidized aquifer sediment from Bangladesh were used to explore the effect of multicomponent adsorption processes on As mobility in a reduced Holocene floodplain aquifer along the Red River, Vietnam. The SCMs for ferrihydrite and goethite yielded very different results. The ferrihydrite SCM favors As(III) over As(V) and has carbonate and silica species as the main competitors for surface sites. In contrast, the goethite SCM has a greater affinity for As(V) over As(III) while PO43− and Fe(II) form the predominant surface species. The SCM for Pleistocene aquifer sediment resembles most the goethite SCM but shows more Si sorption. Compiled As(III) adsorption data for Holocene sediment was also well described by the SCM determined for Pleistocene aquifer sediment, suggesting a comparable As(III) affinity of Holocene and Pleistocene aquifer sediments. A forced gradient field experiment was conducted in a bank aquifer adjacent to a tributary channel to the Red River, and the passage in the aquifer of mixed groundwater containing up to 74% channel water was observed. The concentrations of As (&lt;0.013 μM) and major ions in the channel water are low compared to those in the pristine groundwater in the adjacent bank aquifer, which had an As concentration of ∼3 μM. Calculations for conservative mixing of channel and groundwater could explain the observed variation in concentration for most elements. However, the mixed waters did contain an excess of As(III), PO43− and Si which is attributed to desorption from the aquifer sediment. The three SCMs were tested on their ability to model the desorption of As(III), PO43− and Si. Qualitatively, the ferrihydrite SCM correctly predicts desorption for As(III) but for Si and PO43− it predicts an increased adsorption instead of desorption. The goethite SCM correctly predicts desorption of both As(III) and PO43− but failed in the prediction of Si desorption. These results indicate that the prediction of As mobility, by using SCMs for synthetic Fe-oxides, will be strongly dependent on the model chosen. The SCM based on the Pleistocene aquifer sediment predicts the desorption of As(III), PO43− and Si quite superiorly, as compared to the SCMs for ferrihydrite and goethite, even though Si desorption is still somewhat under-predicted. The observation that a SCM calibrated on a different sediment can predict our field results so well suggests that sediment based SCMs may be a feasible way to model multi-component adsorption in aquifers.