Batch and continuous removal of arsenic using hyacinth roots

Arsenic is considered a primary pollutant in drinking water because of its high toxicity. The unique property of water hyacinth roots (Eichhornia crassipes) to remove heavy metals is of great signiicance for the development of a cost-effective phytoremediation technology. An experimental test program was conducted at the United States Environmental Protection (USEPA) Test and Evaluation (T&E) Facility in Cincinnati, Ohio, to investigate the potential of water hyacinth roots to remove arsenic from spiked drinking water samples. Water hyacinth roots were washed, dried, and powdered to provide dried hyacinth roots (DHR) for batch and continuous column experiments, Various quantities of DHR were added to water spiked with 300 micrograms per liter (microg/L) arsenic. A concentration of 20 g/L DHR was found adequate for greater than 90% arsenic removal in the batch tests. Based on the batch test results, continuous column experiments were performed using a 2-L column. In a continuous system, 15 L of water containing 300 microg/L arsenic were treated to below 20 microg/L using 50 g DHR, and 44 L of water containing 600 microg/L arsenic were treated to below 20 microg/L using 100 g DHR, giving a specific accumulation rate of approximately 260 microg As/g DHR.     

Determination of Arsenic in Scalp Hair of Children and its Correlation with Drinking Water in Exposed Areas of Sindh Pakistan

This study was focused on the analysis of arsenic (As) levels in scalp hair of children (age, <10 years) collected from two towns of Khairpur, Pakistan, to evaluate the effects of As-contaminated groundwater. For comparative purposes, scalp hair samples of children were also collected from that area having low levels of As (<10 μg/L) in drinking water. Groundwater and scalp hair samples of children were collected and analyzed by electrothermal atomic absorption spectrometry prior to microwave-assisted acid digestion. The average As concentrations in groundwater samples of two towns, Thari Mirwah and Gambat, were found to be 28.5 and 98.3 μg/L, respectively. The range of As concentrations in scalp hair samples of children who belong to Thari Mirwah and Gambat was 1.25-1.61 μg/g and 1.73-3.63 μg/g, respectively. Twenty percent of the total children who belong to Gambat have skin lesions on their hands and feet. A positive correlation coefficient (R = 0.91-0.99) was obtained between As contents in drinking water and scalp hairs of children of both towns.     

Arsenic in Biogenic Iron Minerals from a Contaminated Environment

High arsenic levels have been found in some water samples from the Iron Quadrangle, a main gold, manganese and iron mining region in Brazil. In this work, we used transmission electron microscopy coupled to energy-dispersive X-ray analysis to show arsenic in bacteriogenic iron minerals (BIOS) collected in this region. Two types of iron bacteria stalks and several morphologically different filamentous sheaths of bacteria were found, most containing arsenic. Bacterial stalks were partially coated by spherical precipitates probably deposited after stalk secretion. Arsenic/iron ratios were the same independently of the amount of spherical precipitates, suggesting that arsenic incorporation is independent of bacterial metabolism. Additionally, arsenic seems to be saturated in these minerals, since the arsenic/iron ratio was the same under different arsenic concentrations.     

Boron ameliorates arsenic‐induced DNA damage,proinflammatory cytokine gene expressions,oxidant/antioxidant status,and biochemical parameters in rats

Arsenic, an element found in nature, causes hazardous effects on living organisms. Meanwhile, natural compounds exhibit protective effects against hazardous substances. This study evaluated the effects of boron against arsenic‐induced genotoxicity and altered biochemical parameters in rats. Thirty‐five male Wistar albino rats were equally divided into five groups, and the experimental period lasted 30 days. One group was used as the control, and another group was treated with 100 mg/L arsenic in drinking water. The other groups were orally treated with 5, 10, and 20 mg/kg boron plus arsenic (100 mg/L via drinking water). Arsenic caused changes in biochemical parameters, total oxidant/antioxidant status, and DNA damage in mononuclear leukocytes. Moreover, it increased IFN‐γ, IL‐1β, TNF‐α, and NFκB mRNA expression levels in rat tissue. However, boron treatment improved arsenic‐induced alterations in biochemical parameters and increases in DNA damage and proinflammatory cytokine gene expressions.     

Microbial leaching of arsenic from low‐sulfide gold mine material

Drainages from high‐sulfide tailings near abandoned lode deposits in Alaska, U.S.A., and Yukon, Canada, were found to be acidic, to contain large numbers of Thiobacillus ferrooxidans, and to have high concentrations of dissolved arsenic. Drainages from active placer gold mines are not acidic, but T. ferrooxidans and concentrations of dissolved arsenic exceeding 10 μg/L are found in some streams affected by placer mine drainage. Placer mine material containing low amounts of sulfides (326 (μg/g) and moderately high amounts of arsenic (700 μg/g) was leached with growing cultures of T. ferrooxidans, T. ferrooxidans‐spent filtrate, and acid ferric sulfate. The results showed that while more arsenic was released from this material by growing cultures of T. ferrooxidans than by abiotic controls, acid ferric sulfate released much more arsenic than did either growing cultures of T. ferrooxidans or spent culture filtrate containing oxidized iron. Cation exchange chromatography showed that oxidized iron from T. ferrooxidans culture filtrate is chemically less reactive than the iron in aqueous solutions of ferric sulfate salt. These results indicate that arsenic release from both high‐ and low‐sulfide mine wastes is enhanced biologically, but that rates and amounts of arsenic release are primarily controlled by iron species.     

Arsenic in groundwater and its health risk assessment in drinking water of Mailsi,Punjab, Pakistan

The present study was aimed at assessing drinking water quality regarding arsenic (As) and its impact on health from Mailsi (Punjab), Pakistan. Forty-four groundwater samples were collected from two sites, Sargana and Mailsi. Arsenic and other cations were determined by atomic absorption spectrophotometer, whereas the anions were determined either through titration or spectrophotometer. The results revealed that dominant anions were HCO₃^? and Cl^?, Ca⁺² was the dominant cation, and overall water chemistry of the area was CaMgHCO₃^? type. Arsenic concentrations were high, ranging from 11 to 828 µg/L that crossed the World Health Organization permissible limits. Likewise, higher SO₄^?2 concentrations ranging from 247 to 1053 mg/L were observed. The health risk index was higher in the Sargana site, which employed the differences in terms of higher Average Daily Dose, Hazard Quotient, and Carcinogenic Risk of arsenic, which is unsuitable for drinking purposes. The area seems to be at high risk due to arsenic pollution and wells have never been tested for arsenic concentrations earlier; therefore, necessary measures should be taken to test the wells with respect to arsenic.     

Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water

Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system.     

Phytoremediation of arsenic-contaminated groundwater by the arsenic hyperaccumulating fern Pteris vittata L

Arsenic concentrations in a much larger fraction of U.S. groundwater sources will exceed the maximum contaminant limit when the new 10 microg L(-1) EPA standard for drinking water takes effect in 2006. Thus, it is important to develop remediation technologies that can meet this new standard. Phytoremediation of arsenic-contaminated groundwater is a relatively new idea. In this research, an arsenic-hyperaccumulating fern, commonly known as Chinese Brake fern (Pteris vittata L.), was grown hydroponically to examine its effectiveness in arsenic removal from what is believed to be herbicide-contaminated groundwater. One plant grown in 600 mL of groundwater effectively reduced the arsenic concentration from 46 to less than 10 microg L(-1) in 3 days. Re-used plants continued to take up arsenic from the groundwater, albeit at a slower rate (from 46 to 20 microg L(-1) during the same time). Young fern plants were more efficient in removing arsenic than were older fern plants of similar size. The addition of a supplement of phosphate-free Hoagland nutrition to the groundwater had little effect on arsenic removal, but the addition of phosphate nutrition significantly reduced its arsenic affinity and, thus, inhibited the arsenic removal. This study suggested that Chinese Brake has some potential to remove arsenic from groundwater.     

Enhanced frequency of micronuclei in individuals exposed to arsenic through drinking water in West Bengal, India

In West Bengal, India arsenic in ground water has been found to be above the maximum permissible limit in seven districts covering an area of 37,493km2. In the present study, evaluation of the micronuclei (MN) formation in oral mucosa cells, urothelial cells and peripheral blood lymphocytes was carried out in the symptomatic individuals exposed to arsenic through drinking water. Forty five individuals with cutaneous signs of arsenicism from four affected districts (368.11 microg/l of As in drinking water) were considered as the exposed group and 21 healthy individuals with no symptoms of arsenic poisoning and residing in two unaffected districts (5.49 microg/l of As) were considered as controls. The exposed and control groups had similar age distribution and socioeconomic status. Standardised questionnaires were utilised and medical examination was conducted to ascertain exposure history, sociodemographic characteristics, diet, health, medication, addiction and chief symptoms in the study participants. Arsenic exposure was confirmed by measuring the arsenic content in the drinking water, nails, hair and urine samples from the volunteers. Arsenic contents in the urine, nail and hair in the exposed group were 24.45 microg/l, 12.58 and 6.97 microg/g, respectively which were significantly high in comparison to corresponding control group values of 4.88 microg/l, 0.51 and 0.34 microg/g, respectively. Exposed individuals showed a statistically significant increase in the frequency of MN in oral mucosa, urothelial cells and lymphocytes (5.15, 5.74 and 6.39/1000 cells, respectively) when compared with the controls (0.77, 0.56 and 0.53/1000 cells, respectively). Thus, the above results indicate that the symptomatic individuals exposed to arsenic through drinking water in this region have significant cytogenetic damage.     

The effect of a milk diet on the retention of 74As labelled arsenic in mice

The effect of 3 diets with different proportion of milk proteins on retention of arsenic was studied in mice. Arsenic was administered via drinking water in concentration 50 mg As [III] per litre labelled with 74As in amount 2.96 MBq per 100 ml. After 2, 4, 8, 16 and 32 days of exposure the mice in groups of 6 each from all 3 experimental cohorts were decapitated and the content of 74As was determined in whole body, blood, liver, kidneys, spleen, lungs and heart by measuring of the activity in Gamma Scintillation Counter Tesla. From the intake of drinking water and amount of arsenic found in the experimental animals was calculated retention of arsenic in mice at different exposure intervals in all three diets. The values of arsenic found at the exposure intervals in examined materials of all three experimental cohorts were compared. The results obtained indicate that a milk diet has no adverse effect at exposure to arsenic in the sense of enhancing of its retention in mice at given experimental conditions. The found data seemed to suggest that the milk protein rich diet caused retardation of the increase of arsenic concentrations in blood, liver and kidneys that might lead at a lower exposure rate to a decrease in arsenic content in tissues of exposed animals.     

Arsenic Ingestion and Bladder Cancer Mortality—What Do the Dose-Response Relationships Suggest About Mechanism?

The Black–Foot Disease (BFD) endemic area of SW Taiwan has historically been the principal data source for assessing cancer risks from arsenic in drinking water in the United States, most recently in a 42–village ecological study. The data showed a discontinuity for bladder cancer risk at about 400 μg/L. A proposed explanation was that the arsenic–dependent bladder cancer risk was found only for those villages that were dependent on water from the artesian well aquifer (As > 350 μg/L and co–contamination with humic acids) and not for those villages receiving water from the shallow aquifer (As < 350 μg/L without humic acids). The humic acids were present from the algae that grew in the uncovered tanks holding the artesian water. The risk factors (slopes) developed from these subpopulations of the SW Taiwan study were applied to the data from an ecological study of median groundwater arsenic concentration and bladder cancer mortality in 133 U.S. counties dependent on groundwater to determine the slope most predictive of U.S. experience for bladder cancer mortality and arsenic ingestion (Lamm et al. 2004 Lamm, S H, Engel, AKruse, M B. 2004. Arsenic in drinking water and bladder cancer mortality in the United States: An analysis based on 133 U.S. counties and 30 years of observation.. J Occup Environ Med, 46(3): 298–306. [PUBMED][INFOTRIEVE][CSA][Crossref], [PubMed], [Web of Science ®] [Google Scholar]).The U.S. data excluded the SW Taiwan slope estimate derived from the artesian well–dependent subpopulation but were consistent with the slope estimate derived from the subpopulation using shallow aquifer water. Both the SW Taiwan data in the absence of high arsenic levels (< 350 μg/L) and humic acids and the U.S. 133–county data with As < 60 μg/L are consistent with no increased bladder cancer mortality risk from drinking water arsenic concentrations in the exposure range of observation. These analytic results are consistent with both co–carcinogenesis and high–exposure (hundreds of μ g/L As) dependence models of toxicological mode–of–action. These dose–response relationships should influence prioritization in the remediation of arsenic–contaminated drinking water supplies.     

Uncertainty in cancer risk at low doses of inorganic arsenic

It is unknown whether inorganic arsenic in drinking water concentrations at the current maximum contaminant level of 50 μg/1 poses a cancer risk in the United States. Data from two large epidemiological studies of cancer and arsenic in drinking water in Taiwan indicate a dose‐response relationship, but the magnitude of risk at low concentrations is highly uncertain. Four sources of uncertainty are described: model choice, data aggregation, intra‐village variability of arsenic in well water, arsenic intake from food. New data from an appropriately designed epidemiological study are needed to improve dose‐response assessment.     

Arsenic resistance and removal by marine and non-marine bacteria

Arsenic resistance and removal was evaluated in nine bacterial strains of marine and non-marine origins. Of the strains tested, Marinomonas communis exhibited the second-highest arsenic resistance with median effective concentration (EC(50)) value of 510 mg As l(-1), and was capable of removing arsenic from culture medium amended with arsenate. Arsenic accumulation in cells amounted to 2290 microg As g(-1) (dry weight) when incubated on medium containing 5 mg As l(-1) of arsenate. More than half of the arsenic removed was related to metabolic activity: 45% of the arsenic was incorporated into the cytosol fraction and 10% was found in the lipid-bound fraction of the membrane, with the remaining arsenic considered to be adsorbed onto the cell surface. Potential arsenic resistance and removal were also examined in six marine and non-marine environmental water samples. Of the total bacterial colony counts, 28-100% of bacteria showed arsenic resistance. Some of the bacterial consortia, especially those from seawater enriched with arsenate, exhibited higher accumulated levels of arsenic than M. communis under the same condition. These results showed that arsenic resistant and/or accumulating bacteria are widespread in the aquatic environment, and that arsenic-accumulating bacteria such as M. communis are potential candidates for bioremediation of arsenic contaminated water.     

Determination of Arsenic Scalp Hair of Pakistani Children and Drinking Water for Environmental Risk Assessment

This cross-sectional study measured the arsenic level in scalp hair samples of children from two age groups exposed to contaminated underground water in Pakistan. The As concentrations in water and scalp hair samples were analyzed by electrothermal atomic absorption spectrometry. The studied areas were divided into three regions based on concentration of As in water and scalp hair of children who had been exposed to different levels of As through drinking water. The average As concentrations in underground water samples of sub-districts Faiz Ganj, Thari Mirwah, and Gambat were observed to be 15.2, 28.5, and 98.3 μg/L, respectively, which were marked as less, medium, and highly contaminated areas, respectively. The proportion of the children with lower body mass index significantly increased with increasing As exposure level; the dose–response relationship was consistently observed among the subgroups. The range of As concentrations in scalp hair samples of children of age 1–5 and 6–10 years was 0.21–3.88 and 0.32–3.63 μg/g, respectively. Thus, it is likely that children in our study areas are chronically exposed to As through drinking groundwater, suggesting that there is an urgent need to take immediate solution, especially in the Gambat sub-district.     

Transformation of Arsenobetaine and Growth of Bacteria on Zeolitic Tuffs

Arsenobetaine (AsB) is a known organoarsenical of harmless toxicity. It is formed mainly by the metabolization of arsenate in marine organisms such as fish, mollusks and crustaceans. Preliminary investigations have shown that AsB can be degraded in contact with zeolites used as feed additives. Employing high‐performance liquid chromatography (HPLC) combined with simultaneous parallel electrospray ionization (ESI) and inductively coupled plasma mass spectrometric (ICP‐MS) detection, the formation of degradation products was monitored over fifty days in batch reactors containing AsB and clinoptilolites in an aqueous solution. After a 50‐day contact with different natural Mexican zeolites, the AsB concentration decreased by 37 to 100 %. In contrast, no degradation products of AsB were detected after contact with a synthetic clinoptilolite. The formation of dimethyl (1‐carboxymethyl) arsine and arsenate proceeded with different yields in the set of four natural zeolites. To search for the presence of bacteria on the zeolites as an alternative explanation for the metabolism of AsB in our experiments, the growth of microorganisms was studied on two natural clinoptilolites from Hungary and Mexico after severe acid wash. After 10 days of cultivation in iron and sulfur media, almost a threefold increase of the microbial population was observed. In further experiments on the retention of inorganic arsenic, one sample retained, for example, 25 μg/g As(V) and 2.5 μg/g As(III) from a 400 μg/L arsenic solution.     

Arsenic-resistant bacteria solubilized arsenic in the growth media and increased growth of arsenic hyperaccumulator Pteris vittata L

The role of arsenic-resistant bacteria (ARB) in arsenic solubilization from growth media and growth enhancement of arsenic-hyperaccumulator Pteris vittata L. was examined. Seven ARB (tolerant to 10 mM arsenate) were isolated from the P. vittata rhizosphere and identified by 16S rRNA sequencing as Pseudomonas sp., Comamonas sp. and Stenotrophomonas sp. During 7-d hydroponic experiments, these bacteria effectively solubilized arsenic from the growth media spiked with insoluble FeAsO? and AlAsO? minerals (from < 5 μg L?1 to 5.04-7.37 mg L?1 As) and enhanced plant arsenic uptake (from 18.1-21.9 to 35.3-236 mg kg?1 As in the fronds). Production of (1) pyochelin-type siderophores by ARB (fluorescent under ultraviolet illumination and characterized with thin layer chromatography) and (2) root exudate (dissolved organic C) by P. vittata may be responsible for As solubilization. Increase in P. vittata root biomass from 1.5-2.2 to 3.4-4.2 g/plant dw by ARB and by arsenic was associated with arsenic-induced plant P uptake. Arsenic resistant bacteria may have potential to enhance phytoremediation of arsenic-contaminated soils by P. vittata.     

An integrated health risk assessment of indigenous children exposed to arsenic in Sonora,Mexico

Exposure to inorganic arsenic (InAs) through drinking water, even at low to moderate concentrations, is a global public health problem. The objectives of this study were to estimate the risk ratio (HQ), cancer risk (R), and DNA damage (comet assay) of children from three indigenous Yaqui populations located in southern Sonora, Mexico, who were exposed to InAs through drinking water. A cross-sectional study was employed, and analysis of InAs in water and urine was performed via HPLC/ICP-MS. InAs levels in drinking water from Pótam, Vícam, and Cócorit were 108.2, 36.0, and 6.2 μg/L^?1 respectively. Children from Pótam had arsenic concentrations in urine of 107.1 μg As L^?1 compared with 40.3 μg As L^?1 for the children of Cócorit. The HQ values for the children of Pótam, Vícam, and Cócorit were 16.64, 6.02, and 0.94, while the R values were 9.4E-04, 3.5E-04, and 5.7E-05, respectively. Children with the highest arsenic exposure had significantly increased DNA damage (OTM = 14.4 vs. 4.3) [p < 0.0005] which positively correlated with urinary arsenic levels (r = 0.56, p < 0.0001). In conclusion, children of Pótam and Vícam are at significant risk of developing chronic diseases and cancers associated with chronic exposure to this metalloid.     

A survey of arsenic, manganese, boron, thorium, and other toxic metals in the groundwater of a West Bengal, India neighbourhood

Around 150 million people are at risk from arsenic-contaminated groundwater in India and Bangladesh. Multiple metal analysis in Bangladesh has found other toxic elements above the World Health Organization (WHO) health-based drinking water guidelines which significantly increases the number of people at risk due to drinking groundwater. In this study, drinking water samples from the Bongaon area (North 24 Parganas district, West Bengal, India) were analyzed for multiple metal contamination in order to evaluate groundwater quality on the neighbourhood scale. Each sample was analyzed for arsenic (As), boron (B), barium (Ba), chromium (Cr), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), and uranium (U). Arsenic was found above the WHO health-based drinking water guideline in 50% of these tubewells. Mn and B were found at significant concentrations in 19% and 6% of these tubewells, respectively. The maps of As, Mn, and B concentrations suggest that approximately 75% of this area has no safe tubewells. The concentrations of As, Mn, B, and many other toxic elements are independent of each other. The concentrations of Pb and U were not found above WHO health-based drinking water guidelines but they were statistically related to each other (p-value = 0.001). An analysis of selected isotopes in the Uranium, Actinium, and Thorium Radioactive Decay Series revealed the presence of thorium (Th) in 31% of these tubewells. This discovery of Th, which does not have a WHO health-based drinking water guideline, is a potential public health challenge. In sum, the widespread presence and independent distribution of other metals besides As must be taken into consideration for drinking water remediation strategies involving well switching or home-scale water treatment.     

The Effects of Boron on Arsenic‐Induced Lipid Peroxidation and Antioxidant Status in Male and Female Rats

The aim of the present study was to investigate the possible protective effects of boron, an antioxidant agent, against arsenic‐induced oxidative stress in male and female rats. In total, 42 Wistar albino male and female rats were divided into three equal groups: The animals in the control group were given normal drinking water, the second group was given drinking water with 100 mg/L arsenic, and the third group was orally administered drinking water with 100 mg/kg boron together with arsenic. At the end of the 28‐day experiment, arsenic increased lipid peroxidation and damage in the tissues of rats. However, boron treatment reversed this arsenic‐induced lipid peroxidation and activities of antioxidant enzymes in rats. Moreover, boron exhibited a protective action against arsenic‐induced histopathological changes in the tissues of rats. In conclusion, boron was found to be effective in protecting rats against arsenic‐induced lipid peroxidation by enhancing antioxidant defense mechanisms.     

Arsenic (III) oxidation of water applying a combination of hydrogen peroxide and UVC radiation

Arsenic is toxic to both plants and animals and inorganic arsenicals are proven carcinogens in humans. The oxidation of As(III) to As(v) is desirable for enhancing the immobilization of arsenic and is required for most arsenic removal technologies. The main objective of this research is to apply an Advanced Oxidation Process that combines ultraviolet radiation and hydrogen peroxide (UVC/H(2)O(2)) for oxidizing aqueous solutions of As(III). For that purpose, a discontinuous photochemical reactor (laboratory scale) was built with two 40 W tubular germicidal lamps (λ = 253.7 nm) operating inside a recycling system. The study was made beginning with a concentration of 200 μg L(-1) of As(III), changing the H(2)O(2) concentration and the spectral fluence rate on the reactor windows. Based on references in the literature on the photolysis of hydrogen peroxide, arsenic oxidation and our experimental results, a complete reaction scheme, apt for reaction kinetics mathematical modelling, is proposed. In addition, the effectiveness of arsenic oxidation was evaluated using a raw groundwater sample. It is concluded that the photochemical treatment of As(III) using H(2)O(2) and UVC radiation is a simple and feasible technique for the oxidation of As(III) to As(v).