Narrow Results

Adsorption is widely applied to remove arsenic from water. This paper reviewed and compared the recent progresses on the arsenic removal by adsorption using two-dimensional and three-dimensional graphene-based materials as adsorbents. Functional graphene sheet achieved the largest As(III) adsorption capacity of 138.79mg/g, while Mg-Al LDH/GO2 showed the largest As(V) adsorption capacity of 183.11mg/g. Parameters including pH, temperature, co-existing ions and loaded metal or metal oxide affected the adsorption process. The adsorption mechanisms of graphene-based materials for As(III) and As(V) could be explained by surface complexation and the electrostatic attraction, respectively. Future works are suggested to focus on regenerating of two-dimensional graphene-based adsorbents and developing the three-dimensional with large specific surface area and better adsorption performance.

The World Health Organization has labeled the problem of arsenic contamination of groundwater in South Asia as “the largest mass poisoning in human history.” Various technical solutions to the problem fall into one of two broad categories: (i) cleaning contaminated water before human consumption and (ii) encouraging people to switch to less contaminated water sources. In this paper, we review research on the behavioral, social, political, and economic factors that determine the field-level effectiveness of the suite of technical solutions and the complexities that arise when scaling such solutions to reach large numbers of people. We highlight the conceptual links between arsenic-mitigation policy interventions and other development projects in Bangladesh and elsewhere, as analyzed by development economists, that can shed light on the key social and behavioral mechanisms at play. We conclude by identifying the most promising policy interventions to counter the arsenic crisis in Bangladesh. We support a national well-testing program combined with interventions that address the key market failures (affordability, coordination failures, and elite and political capture of public funds) that currently prevent more deep-well construction in Bangladesh.

Recent advances in the chemistry of main group porphyrin complexes are surveyed. New, unprecedented structural types for porphyrin complexes which have been revealed from the recent reports of boron and tellurium porphyrins are described. Advances in the preparation and reactivity of Group 14 (silicon and tin) and Group 15 porphyrin complexes are discussed. A systematic variation in the out-of-plane distortion (ruffling) of light element Group 14 and 15 porphyrin complexes has become apparent now that a significant number of structurally characterized examples are at hand.

The groundwater pollution by arsenic in Bangladesh causes a serious problem for millions of people who are exposed to poisoning by this toxic element. In an attempt to evaluate the extent of arsenic poisoning, hair samples of people living in Pabna district were collected. The hair samples were analyzed using Proton Induced X-ray Emission (PIXE) through exciting the atoms of a specimen so that their intensities can be converted into elemental concentrations in the specimen. The elements present in the specimen are identified by the corresponding X-ray energies and their concentrations are deduced from the X-ray intensities. The results from hair samples indicate substantially higher level of arsenic than those demarcated as toxic levels, in people from member families both affected and non-affected by poisoning. We correlate it with exceedingly high arsenic concentration in drinking water far above the permissible limit. The analytical results are compared with the results of arsenic and other elemental analysis of 160 Bangladeshi hair samples with that of 250 Japanese samples. The results show markedly higher levels of arsenic, manganese, iron and lead where the latter three elements show a positive relation with arsenic in the case of Bangladeshi as compared to the samples from Japan. On the other hand, selenium concentrations show very low level in the Bangladeshi samples compared to Japanese, displaying an inverse relationship with arsenic. The mechanism of arsenic in relation to other elements in the human body needs further investigation. The preliminary results call for detailed experimental and epidemiological studies to further characterize these aspects.

This investigation focuses on the arsenic contamination problems in tube well groundwater systems and the different forms of arsenic and other toxic elements accumulated in human hair samples taken in a rural area of Allahabad, Uttar Pradesh, India. The local residents at the study site depend on groundwater as their major source of household water. The oxidation reduction potential (ORP) and pH of groundwater samples were measured directly after the sampling of groundwater. Arsenic concentrations were measured directly in water samples by a colorimetric arsenic analysis kit after the water was pumped from a tube well and/or at a nearby laboratory. Human hair samples from the residents of the villages in the study site were analyzed by PIXE to measure a wide range of elements. An atomic absorption spectrometer was also used to measure arsenic concentrations. The results indicated that the concentrations of arsenic in groundwater and human hair were significantly higher in the village of Bada Kanjasa than in the villages of Kanua and Chota Kanjasa (P< 0.05), clearly indicating that the higher arsenic concentration in groundwater reflected the accumulation of arsenic in human hair in the residents of Bada Kanjasa. The PIXE analysis also revealed an unusually high concentration of lead in human hair samples from Chota Kanjasa. Although the actual health effects and the detailed exposure mechanisms remain to be investigated, lead pollution is suspected to be the source of the exposure.

Traditional Chinese Medicine (TCM) is a practical medicine based on thousands of years of medical practice in China. Arsenic dispensing powder (ADP) has been used as a treatment for MDS patients with a superior efficacy on anemia at Xiyuan Hospital of China Academy of Chinese Medical Sciences. In this study, we retrospectively analyzed MDS patients that received ADP treatment in the past 9 years and confirmed that ADP improves patients’ anemia and prolongs overall survival in intermediate-risk MDS patients. Then, we used the MDS transgenic mice model and cell line to explore the drug mechanism. In normal and MDS cells, ADP does not show cellular toxicity but promotes differentiation. In mouse MDS models, we observed that ADP showed significant efficacy on promoting erythropoiesis. In the BFU-E and CFU-E assays, ADP could promote erythropoiesis not only in normal clones but also in MDS clones. Mechanistically, we found that ADP could downregulate HIF1A in MDS clones through upregulation of VHL, P53 and MDM2, which is involved in two parallel pathways to downregulate HIF1A. We also confirmed that ADP upregulates GATA factors in normal clones. Thus, our clinical and experimental studies indicate that ADP is a promising drug to promote erythropoiesis in both MDS and normal clones with a superior outcome than current regular therapies. ADP promotes erythropoiesis in myelodysplastic syndromes via downregulation of HIF1A and upregulation of GATA factors.

In recent years, the number of artisanal gold miners in Mongolia is drastically increasing. They use mercury to extract gold from ore and release it to the environment and this fact has been an issue of concern in the nation. In order to monitor the degree of exposure to mercury, artisanal miners' hairs from a typical mining site, Boroo, were analyzed by PIXE at Nishina Memorial Cyclotron Center, Japan. The result indicated that mercury content in the hairs is very low in spite of the miners' practice to work in mercury fume for smelting. However the result showed high level of arsenic, up to 3.2 ppm, although miners' do not use arsenic in the smelting process.

Pytoremediation using an arsenic hyperaccumulator, Petris vittata L., has generated an increasing interest worldwide due to both environmentally sound and cost effectiveness. However the mechanism of arsenic accumulation by this fern is not clear at this time. This study examined the uptake of arsenate (As(V)) and arsenite (As(III)) by a hydroponic culture of Pteris vittata using both in-air submilli-PIXE for different parts of the fern and in-air micro-PIXE for the tissue cells. These PIXE analysis systems used 3 MeV proton beams from a 4.5-MV single-ended Dynamitron accelerator at Tohoku University, Japan. The fern took up both arsenate and arsenite from hydroponic solutions which were spiked with 50 mg of arsenic per litter. Final amount of arsenic accumulation in the fern is 1,500 mg per kg (wet weight) of the plant biomass in arsenite treatment and 1,100 mg per kg in arsenate treatment. Arsenic accumulation was not observed at the root parts of the ferns. The in-vivo mapping of elements by submilli-PIXE analyses on the fern laminas showed the arsenic accumulation in the edges of a pinna. The micro-PIXE analyses revealed arsenic maps homogeneously distributed in cells of the lamina, stem and rhizome of the fern. These results indicate that arsenic, both arsenate and arsenite in a contaminated medium are translocated quickly from roots to fronds of Pteris vittata, and distributes homogeneously into tissue cells of the fern laminas.