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

Papers by PHAM KIM TRANG

Geochemical reactive transport modeling in “4D” of groundwater arsenic distribution in a non-static developing fluvial sediment aquifer system—feasibility study based on the upper part of the Red River, Vietnam

Arsenic from groundwater into soils, plants and the food chain: Complementary case studies from West Bengal, Inner Mongolia and the Red River Delta, Vietnam

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

This study demonstrated the contamination levels of polychlorinated biphenyls (PCBs), hydroxylate... more This study demonstrated the contamination levels of polychlorinated biphenyls (PCBs), hydroxylated PCBs (OH-PCBs), polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), hydroxylated PBDEs (OH-PBDEs), and bromophenols (BPhs), and their relationships with thyroid hormones (THs), in the serum of human donors from an e-waste recycling site and a rural site in Hung Yen province, Vietnam. Occupationally related exposure was indicated by significantly higher residue levels of PCBs, OH-PCBs, PBDEs, and BPhs in the serum of donors from the e-waste recycling site (median: 420, 160, 290, and 300 pg g À 1 wet wt, respectively) than those in the serum of donors from the rural site (median: 290, 82, 230, and 200 pg g À 1 wet wt, respectively). On the other hand, levels of OH-/MeO-PBDEs were significantly higher in serum of donors from the reference site (median: 160 and 20 pg g À 1 wet wt, respectively) than in those from the e-waste recycling site (median: 43 and 0.52 pg g À 1 wet wt, respectively). In addition, we implemented stepwise generalized linear models to assess the association between the levels of TH and PCBs, PBDEs, and their related compounds. In females, we found positive associations of PCBs and OH-PCB concentrations with total thyroxine, free thyroxine, total triiodothyronine, and free triiodothyronine, and a negative association with thyroid-stimulating hormone concentrations.

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

Vietnam is an agricultural country with a population of about 88 million, with some 18 million in... more Vietnam is an agricultural country with a population of about 88 million, with some 18 million inhabitants living in the Red River Delta in North Vietnam. The present study reports the chemical analyses of 68 water and 213 biological (human hair and urine) samples conducted to investigate arsenic contamination in tube well water and human arsenic exposure in four districts (Tu Liem, Dan Phuong, Ly Nhan, Hoai Duc) in the Red River Delta. Arsenic concentrations in groundwater in these areas were in the range of <1 to 632 µg/L, with severe contamination found in the communities Ly Nhan, Hoai Duc, and Dan Phuong. Arsenic concentrations were markedly lowered in water treated with sand filters, except for groundwater from Hoai Duc. Human hair samples had arsenic levels in the range of 0.07-7.51 µg/g, and among residents exposed to arsenic levels ≥50 µg/L, 64% of them had hair arsenic concentrations higher than 1 µg/g, which is a level that can cause skin lesions. Urinary arsenic concentrations were 4-435 µg/g creatinine. Concentrations of arsenic in hair and urine increased significantly with increasing arsenic content in drinking water, indicating that drinking water is a significant source of arsenic exposure for these residents. The percentage of inorganic arsenic (IA) in urine decreased with age, whereas the opposite trend was observed for monomethylarsonic acid (MMA) in urine. Significant cointeractions of age and arsenic exposure status were also detected for concentrations of arsenic in hair and the sum of IA, MMA, and dimethylarsinic acid (DMA) in urine and %MMA. In summary, this study demonstrates that a considerable proportion of the Vietnamese population is exposed to arsenic levels of chronic toxicity, even if sand filters reduce exposure in many households. Health problems caused by arsenic ingestion through drinking water are increasingly reported in Vietnam.

Geochimica et Cosmochimica Acta, 2014

The adsorption of arsenic onto aquifer sediment from the Red River floodplain, Vietnam, was deter... more The adsorption of arsenic onto aquifer sediment from the Red River floodplain, Vietnam, was determined in a series of batch experiments. Due to water supply pumping, river water infiltrates into the aquifer at the field site and has leached the uppermost aquifer sediments. The leached sediments, remain anoxic but contain little reactive arsenic and iron, and are used in our experiments. The adsorption and desorption experiments were carried out by addition or removal of arsenic from the aqueous phase in sediment suspensions under strictly anoxic conditions. Also the effects of HCO 3 , Fe(II), PO 4 and Si on arsenic adsorption were explored. The results show much stronger adsorption of As(V) as compared to As(III), full reversibility for As(III) adsorption and less so for As(V). The presence or absence of HCO 3 did not influence arsenic adsorption. Fe(II) enhanced As(V) sorption but did not influence the adsorption of As(III) in any way. During simultaneous adsorption of As(III) and Fe(II), As(III) was found to be fully desorbable while Fe(II) was completely irreversibly adsorbed and clearly the two sorption processes are uncoupled. Phosphate was the only solute that significantly could displace As(III) from the sediment surface. Compiling literature data on arsenic adsorption to aquifer sediment in Vietnam and Bangladesh revealed As(III) isotherms to be almost identical regardless of the nature of the sediment or the site of sampling. In contrast, there was a large variation in As(V) adsorption isotherms between studies. A tentative conclusion is that As(III) and As(V) are not adsorbing onto the same sediment surface sites. The adsorption behavior of arsenic onto aquifer sediments and synthetic Fe-oxides is compared. Particularly, the much stronger adsorption of As(V) than of As(III) onto Red River as well as on most Bangladesh aquifer sediments, indicates that the perception that arsenic, phosphate and other species compete for the same surface sites of iron oxides in sediments with properties similar to those of, for example a synthetic goethite, probably is not correct. A simple two-component Langmuir adsorption model was constructed to quantitatively describe the reactive transport of As(III) and PO 4 in the aquifer.

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.

Transfusion, 2011

The human FUT2 gene encodes a secretor-type a(1,2)fucosyltransferase, and many population-specifi... more The human FUT2 gene encodes a secretor-type a(1,2)fucosyltransferase, and many population-specific polymorphisms have been reported in the coding region. STUDY DESIGN AND METHODS: Direct sequencing, real-time polymerase chain reaction, and high-resolution melt (HRM) analysis were done to detect singlenucleotide polymorphism (SNPs) and copy number variations (CNVs) in a Vietnamese population. The impacts of two novel mutations on the encoded enzyme were examined by a transient expression study. The major nonfunctional allele in the 294 Vietnamese was se 357,385 , whereas no CNV was detected. Two novel SNPs, 818C>A (Thr273Asn) and 853G>A (Ala285Thr), distributed at low frequency, were shown to remarkably affect the enzyme activity. The allelic polymorphism of FUT2 in Vietnamese is similar to that of other East and Southeast Asian populations. This result may reflect the history and gene flow of this population. In addition, HRM analysis seems to be a simple and effective method for screening rare SNPs of FUT2 in a large number of samples. T he secretor-type a(1,2)fucosyltransferase, encoded by FUT2, regulates the expression of the H antigen (essential precursor of A and B antigens) not on red blood cells but on the surface of mucosa and in body fluids and hence determines the secretor status of the ABO(H) antigens. Secretors who have the antigens in saliva and other body fluids have at least one functional FUT2 allele (Se), while homozygotes of nonfunctional FUT2 alleles (se) become nonsecretors who do not express the antigens in saliva and other body fluids. As shown in Table , many single-nucleotide polymorphisms (SNPs) and genetic recombination in the coding

Groundwater arsenic concentrations in Vietnam controlled by sediment age

Nature Geoscience, 2012

Surface complexation modeling of groundwater arsenic mobility: Results of a forced gradient experiment in a Red River flood plain aquifer, Vietnam

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.

Environmental Science & Technology, 2006

Arsenic removal efficiencies of 43 household sand filters were studied in rural areas of the Red ... more Arsenic removal efficiencies of 43 household sand filters were studied in rural areas of the Red River Delta in Vietnam. Simultaneously, raw groundwater from the same households and additional 31 tubewells was sampled to investigate arsenic coprecipitation with hydrous ferric iron from solution, i.e., without contact to sand surfaces. From the groundwaters containing 10-382 μg/L As, 99%, 90%, and 71%, respectively. The concentration of dissolved iron in groundwater was the decisive factor for the removal of arsenic. Residual arsenic levels below 50 μg/L were achieved by 90% of the studied sand filters, and 40% were even below 10 μg/L. Fe/As ratios of ≥50 or ≥250 were required to ensure arsenic removal to levels below 50 or 10 μg/L, respectively. Phosphate concentrations >2.5 mg P/L slightly hampered the sand filter and coprecipitation efficiencies. Interestingly, the overall arsenic elimination was higher than predicted from model calculations based on sorption constants determined from coprecipitation experiments with artificial groundwater. This observation is assumed to result from As(III) oxidation involving Mn, microorganisms, and possibly dissolved organic matter present in the natural groundwaters. Clear evidence of lowered arsenic burden for people consuming sand-filtered water is demonstrated from hair analyses. The investigated sand filters proved to operate fast and robust for a broad range of groundwater composition and are thus also a viable option for mitigation in other arsenic affected regions. An estimation conducted for Bangladesh indicates that a median residual level of 25 μg/L arsenic could be reached in 84% of the polluted groundwater. The easily observable removal of iron from the pumped water makes the effect of a sand filter immediately recognizable even to people who are not aware of the arsenic problem.

Environmental Science & Technology, 2007

Environmental Science & Technology, 2005

In this study, we report the first ever large-scale environmental validation of a microbial repor... more In this study, we report the first ever large-scale environmental validation of a microbial reporter-based test to measure arsenic concentrations in natural water resources. A bioluminescence-producing arsenic-inducible bacterium based on Escherichia coli was used as the reporter organism. Specific protocols were developed with the goal to avoid the negative influence of iron in groundwater on arsenic availability to the bioreporter cells. A total of 194 groundwater samples were collected in the Red River and Mekong River Delta regions of Vietnam and were analyzed both by atomic absorption spectroscopy (AAS) and by the arsenic bioreporter protocol. The bacterial cells performed well at and above arsenic concentrations in groundwater of 7 µg/L, with an almost linearly proportional increase of the bioluminescence signal between 10 and 100 µg As/L (r 2 ) 0.997). Comparisons between AAS and arsenic bioreporter determinations gave an overall average of 8.0% false negative and 2.4% false positive identifications for the bioreporter prediction at the WHO recommended acceptable arsenic concentration of 10 µg/L, which is far better than the performance of chemical field test kits. Because of the ease of the measurement protocol and the low application cost, the microbiological arsenic test has a great potential in large screening campaigns in Asia and in other areas suffering from arsenic pollution in groundwater resources.

Environmental Pollution, 2006

Environmental Pollution, 2009

Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its meta... more Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam.

Environment International, 2008

Chemical Geology, 2008

Groundwater contamination by arsenic in Vietnam poses a serious health threat to millions of peop... more Groundwater contamination by arsenic in Vietnam poses a serious health threat to millions of people. In the larger Hanoi area, elevated arsenic levels are present in both, the Holocene and Pleistocene aquifers. Family-based tubewells predominantly tap the Holocene aquifer, while the Hanoi water works extract more than 600,000 m 3 /day of groundwater from the Pleistocene aquifer. Detailed groundwater and sediment investigations were conducted at three locations exhibiting distinct geochemical conditions, i.e., i) high levels of dissolved arsenic (av. 121 µg/L) at the river bank, ii) low levels of dissolved arsenic (av. 21 µg/L) at the river bank and, iii) medium levels of dissolved arsenic (60 µg/L) in an area of buried peat and excessive groundwater abstraction. Seasonal fluctuations in water chemistry were studied over a time span of 14 months. Sediment-bound arsenic (1.3-22 µg/g) is in a natural range. Arsenic correlates with iron (r 2 N 0.8) with variation related to grain size. Sediment leaching experiments showed that arsenic can readily be mobilized at each of the three locations. Low levels of arsenic in groundwater (b10 µg/L) generally exhibit manganese reducing conditions, whereas elevated levels are caused by reductive dissolution under iron-and sulphate reducing conditions. Average arsenic concentrations in groundwater are twofold higher at the river bank than in the peat area. The lower levels of arsenic contamination in the peat area are likely controlled by the high abundance of iron present in both the aqueous and sediment phases. With median molar Fe/As ratios of 350 in water and 8700 in the sediments of the peat area, reduced iron possibly forms new mineral phases that resorb (or sequester) previously released arsenic to the sediment. Despite similar redox conditions, resorption is much less significant at the river bank (Fe/As(aq) = 68, Fe/ As(s) = 4700), and hence, arsenic concentrations in groundwater reach considerably higher levels. Drawdown of Holocene water to the Pleistocene aquifer in the peat area, caused by the pumping for the Hanoi water works, clearly promotes reducing conditions in Pleistocene groundwater. This demonstrates that excessive abstraction of water from deep