Water Arsenic Concentrations Research Articles

Rapid and noninvasive estimation of human arsenic exposure based on 4-photo-set of the hand and foot photos through artificial intelligence

Chronic exposure to arsenic is linked to the development of cancers in the skin, lungs, and bladder. Arsenic exposure manifests as variegated pigmentation and characteristic pitted keratosis on the hands and feet, which often precede the onset of internal cancers. Traditionally, human arsenic exposure is estimated through arsenic levels in biological tissues; however, these methods are invasive and time-consuming. This study aims to develop a noninvasive approach to predict arsenic exposure using artificial intelligence (AI) to analyze photographs of hands and feet. By incorporating well water consumption data and arsenic concentration levels, we developed an AI algorithm trained on 9988 hand and foot photographs from 2497 subjects. This algorithm correlates visual features of palmoplantar hyperkeratosis with arsenic exposure levels. Four pictures per patient, capturing both ventral and dorsal aspects of hands and feet, were analyzed. The AI model utilized existing arsenic exposure data, including arsenic concentration (AC) and cumulative arsenic exposure (CAE), to make binary predictions of high and low arsenic exposure. The AI model achieved an optimal area under the curve (AUC) values of 0.813 for AC and 0.779 for CAE. Recall and precision metrics were 0.729 and 0.705 for CAE, and 0.750 and 0.763 for AC, respectively. While biomarkers have traditionally been used to assess arsenic exposure, efficient noninvasive methods are lacking. To our knowledge, this is the first study to leverage deep learning for noninvasive arsenic exposure assessment. Despite challenges with binary classification due to imbalanced and sparse data, this approach demonstrates the potential for noninvasive estimation of arsenic concentration. Future studies should focus on increasing data volume and categorizing arsenic concentration statistics to enhance model accuracy. This rapid estimation method could significantly contribute to epidemiological studies and aid physicians in diagnosis.

Arsenic exposure and measures of glucose tolerance in Bangladeshi adults: A cross-sectional study.

Arsenic has been associated with diabetes and impaired glucose tolerance in many studies, although some reports have shown null findings. We conducted a cross-sectional study among 300 adults in Bangladesh. Participants were randomly selected from a roster of 1800 people who previously participated in studies of arsenic and skin lesions. We measured fasting glucose and insulin levels. We assessed drinking water arsenic concentration using graphite furnace atomic absorption spectrophotometry (GF-AAS) and toenail arsenic concentration using inductively coupled mass spectrometry (ICP-MS). We ran covariant-adjusted, linear regression and spline models to examine associations of arsenic concentrations with the homeostatic model assessment of insulin resistance (HOMA-IR), a marker of insulin resistance, and HOMA of beta-cell function (HOMA-β), a marker of beta-cell function. Among 285 participants with complete data, the median (IQR) arsenic concentration was 4.0 (6.9) μg/g in toenails and 39.0 (188.5) μg/L in drinking water. Arsenic concentrations were not associated with insulin resistance or beta-cell function. HOMA-IR was 0.67% lower and HOMA-β was 0.28% lower per µg/g increment in toenail arsenic, but these effect estimates were small, and confidence intervals crossed the null value. Although arsenic exposure has been associated with diabetes, we found no evidence of an adverse effect on insulin resistance or beta-cell function.

Removal of Arsenic from Contaminated Water by Polypyrrole-Based Adsorbents

Worldwide, there is growing concern over the toxicity of arsenic in drinking water. The US Environmental Protection Agency and Central Pollution Control Board (India) have set a safe limit of 50 parts per billion for arsenic in drinking water. Millions of people are at immediate risk due to high concentrations of arsenic in drinking water, particularly in developing nations where arsenic poisoning symptoms have been observed. One of the essential techniques described in this article is the absorption of arsenic from contaminated water by sustainable cellulosic materials like jute and wood sawdust after suitable modification. Jute and sawdust are cheap and abundantly available in South Asia. They are functionalized with polypyrrole coating by in situ chemical polymerization of pyrrole in aqueous medium in the presence of ferric chloride. Polypyrrole-coated jute fabric (with 11.28% polypyrrole add-on) and polypyrrole-coated sawdust (with 5.28% polypyrrole add-on) are found to be excellent adsorbers of arsenic ion (As3+) from water. The effect of dosage of polypyrrole-coated adsorbents, treatment time and pyrrole concentration on the As removal efficiency have been investigated in this work. The arsenic concentration in water is determined using a microwave plasma atomic emission spectrometer with the highest level of accuracy. Maximum As removal efficiency by the polypyrrole-coated sawdust and polypyrrole-coated jute fabric is found to be 80.90% and 97.3%, respectively, from a 50 mL, 7.5 parts per million As solution with a dosage of 1 g at neutral pH. The polypyrrole-coated jute and sawdust are characterized by Fourier-transform infrared spectroscopy to understand the chemical interaction between cellulose and polypyrrole molecules. The scanning electron microscope studies reveal a uniform coating of polypyrrole around the surface of jute fibre and sawdust particles. Thermo-gravimetric analysis shows good thermal stability of jute and sawdust after polypyrrole coating.

The environmental and agronomic benefits and trade-offs linked with the adoption alternate wetting and drying in temperate rice paddies

ContextAlternating wetting and drying (AWD) is an irrigation practice, alternative to continuous flooding, to improve the agro-environmental sustainability of rice cultivation. Benefits include reduction in water consumption, methane (CH4) emissions and arsenic (As) concentrations in grain. However, drainage periods during AWD can negatively affect nitrogen (N) use efficiency by the crop and grain yields, while increasing nitrous oxide (N2O) emissions and cadmium (Cd) contents in grain. ObjectiveThe objective of this study was to provide a holistic evaluation of AWD adoption in temperate rice cropping systems, including associated trade-offs. We hypothesized that the adoption of AWD in water seeded rice paddies can reduce the global warming potential (GWP) without affecting plant N uptake or introducing yield gaps, and also maintain a high quality of rice grain by limiting the uptake of metal(loid)s present in the soil, thereby resulting in an overall positive agro-environmental performance. MethodsIn a two-year field experiment in NW Italy two alternative irrigation practices involving water seeding followed by AWD management of different severity (AWDsafe and AWDstrong) were evaluated relative to the conventional water seeding and continuous flooding (WFL), comparing three different rice varieties. Yields and yield components, plant N uptake, apparent N recovery (ANR), metal(loid) concentrations in grain, and CH4 and N2O emissions were evaluated. ResultsAWDsafe and AWDstrong maintained or increased yields compared to WFL depending on varieties, despite an increase in sterility. There were no consistent differences in N uptake and ANR. Both AWDsafe and AWDstrong significantly reduce As concentration in grain, but significantly increase Cd and nickel (Ni). AWDsafe and AWDstrong reduced CH4 emissions by 45–55 % and 40–73 %, respectively, compared toWFL, while no increase in N2O emissions was observed. This resulted in a reduction in the GWP of 46 and 54 % with AWDsafe and AWDstrong, respectively. Conclusions and ImplicationsAWD was shown to be effective for mitigating GHG emissions from temperate rice cropping systems while maintaining high yield performance comparable or higher than WFL. AWD may represent a viable alternative to continuous flooding to improve agro-environmental sustainability of temperate rice cropping systems, but the trade-off between decreasing As and increasing Cd and Ni contents in the grain may represent an important concern for food safety with the adoption of this alternative water management practice.

Residential sociodemographic characteristics associated with public water arsenic and uranium concentrations, 2006-2011

Residential sociodemographic characteristics associated with public water arsenic and uranium concentrations, 2006-2011

Arsenic Treatment Using Electrolytic Ferrous Reagent to Replace Bulk Ferric Chloride

Key TakeawaysAs federal maximum contaminant level (MCL) recommendations for arsenic in drinking water are being reviewed, US utilities are preparing for more stringent regulations.If faced with reducing its treated water's arsenic concentration to 5 μg/L, the City of Alamosa, Colo., would need to increase its ferric chloride dose—raising supply, cost, and operational concerns.To avoid these issues, the city explored a new technology that generates a ferrous reagent via an in situ electrolytic process to replace bulk ferric chloride.The electrolytic ferrous reagent removed arsenic to below 5 μg/L, reduced permeate manganese levels, and improved effluent quality with a far lower coagulant dose.

Arsenic Adsorption Isotherms of Sediments from Old Mining Area and Their Implications: A Case Study of the Ron Phibun Area, Thailand

Although tin mining activities in the southern part of Thailand have been abandoned for more than 40 years, arsenic contamination in old tin-mining areas continues to pose a health risk. Fortunately, natural adsorption of arsenic by sediment has reduced the arsenic concentration in water to the maximum allowable level within a 10-kilometre radius of the mine sources. This article attempts to characterize the arsenic adsorption properties of sediment along a water creek which passes through the old tin-mine areas in Ron Phibun district, Nakhon Si Thammarat province, Thailand, where the contamination has been most severe. It was found that Fe tends to be associated with the adsorption capacity of arsenic in sediment. However, pH 4 and pH 7 did not associate with adsorption capacity. At pH 12, the solubility of arsenic increases, making it less likely to be adsorbed into the sediment and more likely to dissolve in water. For the adsorption isotherms of the sediment, the so-called ‘2-step Langmuir/Freundlich models’, with the advance of switching functions (Logistic or Arctan functions), were proposed. Then, based on the principle of parsimony, a stepwise model reduction approach was used to choose the optimal models. It was found that the isotherms were used successfully to describe the historical arsenic-contamination data of the past 14 years (2005 - 2019) and to predict future trends qualitatively. HIGHLIGHTS Two-step Langmuir/Freundlich models with the switching functions were proposed The historical arsenic-contamination data of the past 14 years (2005 - 2019) was examined The model described the historical arsenic-contamination data as a function of pH and metal-complex formation in sediment soils successfully GRAPHICAL ABSTRACT

Arsenic Exposure-Related Hypertension in Bangladesh and Reduced Circulating Nitric Oxide Bioavailability.

Hypertension is a major cause of death worldwide. Although arsenic exposure has been associated with the risk of hypertension, this association appears nonuniform due to inconsistent results from studies conducted in different populations. Moreover, hypertension is a complex condition with multiple underlying mechanisms and factors. One factor is impaired production and bioavailability of vascular nitric oxide (NO). However, the implications of the effects of arsenic exposure on circulating NO and its association with hypertension in humans are largely unknown. We investigated the dose-response relationship between arsenic exposure and hypertension with vascular NO levels as a potential mediator of arsenic-related hypertension in individuals exposed to a broad range of arsenic. A total of 828 participants were recruited from low- and high-arsenic exposure areas in Bangladesh. Participants' drinking water, hair, and nail arsenic concentrations were measured by inductively coupled plasma mass spectroscopy. Hypertension was defined as a systolic blood pressure (SBP) value of and a diastolic (DBP) value of . Serum NO levels reflected by total serum nitrite concentrations were measured by immunoassay. A formal causal mediation analysis was used to assess NO as a mediator of the association between arsenic level and hypertension. Increasing concentrations of arsenic measured in drinking water, hair, and nails were associated with the increasing levels of SBP and DBP. The odds of hypertension were dose-dependently increased by arsenic even in participants exposed to relatively low to moderate levels () of water arsenic [odds ratios (ORs) and 95% confidence intervals (CIs): 2.87 (95% CI: 1.28, 6.44), 2.67 (95% CI: 1.27, 5.60), and 5.04 (95% CI: 2.71, 9.35) for the , , and groups, respectively]. Causal mediation analysis showed a significant mediating effect of NO on arsenic-related SBP, DBP, and hypertension. Increasing exposure to arsenic was associated with increasing odds of hypertension. The association was mediated through the reduction of vascular NO bioavailability, suggesting that impaired NO bioavailability was a plausible underlying mechanism of arsenic-induced hypertension in this Bangladeshi population. https://doi.org/10.1289/EHP13018.

Arsenic In Surface Waters In The Central Part Of The North Caucasus And Correspondent Health Risk Assessment

Arsenic is ranked as a significant global health hazard associated with potable water. The present study assesses the arsenic pollution of the surface waters in the mountainous regions of the central part of the North Caucasus due to the presence of geochemical anomalies and the potential health risk by its consumption for the residents. The studies were carried out from 2016 to 2022. The surface waters of 5 main rivers of the region (Kuban, Malka, Baksan, Chegem and Cherek) with their main tributaries have been studied. Samples were taken during the period of intensive melting of glaciers (summer). The determination of the soluble form of arsenic was carried out using the method of atomic absorption spectrometry. In general, arsenic concentrations in this region are lower than Clark values for river waters. Along with this, watercourses with high and very high concentrations of arsenic have been identified. Elevated concentrations of arsenic in surface waters spatially coincide with the location of geochemical anomalies. The most polluted is the Baksan River. The levels of surface waters pollution from natural and anthropogenic sources are almost the same (up to 100 µg/dm3). In this regard, an assessment of the health hazard was carried out. For residents receiving drinking water from wells located at the southern foot of Elbrus, the carcinogenic risk for adults was 4.51×10-4, which is unacceptable for the general population. The non–carcinogenic risk was 1.00 - the maximum permissible risk causing concern.

Evaluación de concentración de arsénico para proponer la alternativa de remediación en el río Ananea

This study addresses the problem of arsenic contamination of water from the Ananea River due to artisanal and informal mining. The main objective is to evaluate arsenic contamination of waters of the Ananea River and remediation alternatives, during the 12 months of 2018 to 2019. The results reveal that the concentration of arsenic in water at point P-A located in the Sillacunca lagoon was 0.926 mg/l, 0.527 mg/l, 0.730 mg/l; in sediments 117.475 mg/kg, 74.8 mg/kg, 92.50 mg/kg; at the point of monitoring P-B located in the Ananea River 100 meters upstream confluence with the Lunar de Oro River, the concentration of arsenic in water is 0.422 mg/l, 0.221 mg/l, 0.225 mg/l; in sediments it is 56.73 mg/kg, 26.77 mg/kg, 62.5 mg/kg. The concentration of arsenic in the area of the Sillacunca lagoon and in the area in the Ananea river 100 meters upstream confluence with the Lunar de Oro river presented a higher concentration.

Biomarkers of arsenic exposure in biogeochemical provinces

Introduction. One of the direct methods of assessing the impact of contaminants on public health is the use of biological markers that allow determining the presence of a substance or its metabolite in human biological tissues and the dose received from all sources of this substance. 
 The purpose of this study was to determine the dependence of arsenic content in biological samples (hair) 
 of exposed residents on the level of its content in drinking water and to substantiate the effectiveness of the use of this biomarker in the conditions of a hydrogeochemical province in the Republic of Dagestan.
 Material and methods. During this research the arsenic content in the hair of the exposed residents was measured with further comparison of the data obtained with its content in drinking groundwater. To determine the arsenic content in the hair of the exposed residents, an atomic absorption method was used with preliminary preparation of biosubstrate samples. Socio-demographic data were obtained from a questionnaire. Statistical data processing was carried out using Microsoft Excel.
 Results. In the course of this study, a correlation was revealed between the arsenic content in the hair of the exposed residents and its content in the drinking water consumed, and a direct proportional relationship between these values was also revealed. Thus, with an increase in the concentration of arsenic in water by 
 0.1 mg/l, the arsenic content in the hair increases by 0.14 mkg/g. So, using of the hair of exposed residents as a biomarker of long-term exposure is recommended to small doses of arsenic in a biogeochemical province.
 limitation of the study is the small sample size. However, this does not prevent the assessment of the effectiveness of using hair as a biomarker of arsenic exposure and preliminary conclusions for subsequent in-depth analysis of biomonitoring in the conditions of biogeochemical provinces.
 Conclusion. As a rule, the content of natural toxic elements is characterized by trace amounts in the conditions of biogeochemical provinces. Biomonitoring will reveal the level of stress on the body and timely apply preventive methods before the clinical signs of intoxication are revealed.

Chemical composition of arsenic-based acid mine drainage in the downstream of a gold mine: Fuzzy regression and clustering analysis

This study employs fuzzy regression and fuzzy multivariate clustering techniques to analyze arsenic-polluted water samples originating from acid rock drainage in waste rock dumps. The research focuses on understanding the complex relationships between variables associated with arsenic contamination, such as water arsenic concentration, pH levels, and soil characteristics. To this end, fuzzy regression models were developed to estimate the relationships between water arsenic concentration and independent variables, thus, incorporating the inherent uncertainties into the analysis. Furthermore, multivariate fuzzy k-means clustering analysis facilitated the identification of fuzzy-based clusters within the dataset, providing insights into spatial patterns and potential sources of arsenic pollution. The pairwise comparisons indicated the strongest correlation of 0.62 between soil total arsenic and pH, while the weakest correlation of 0.13 was observed between soil-soluble arsenic and soil iron, providing valuable insights into their relationships and impact on water arsenic levels. The associated uncertainties in the relationships among the variables were determined based on the degree of belongingness of each data point to various fuzzy sets. Three distinct clusters emerged from the analysis: Cluster 1 comprised Points 5, 6, and 7; Cluster 2 included Points 1, 2, 3, 4, 8, and 9; and Cluster 3 consisted of Points 10, 11, 12, and 13. The findings enhance our understanding of the factors influencing arsenic contamination to provide an effective mitigation strategy in acid rock drainage scenarios. This research also demonstrates the applicability and effectiveness of fuzzy regression and fuzzy multivariate clustering in the analysis of arsenic-polluted water samples.

Separation of Boron and Arsenic from Geothermal Water with Novel Gel-Type Chelating Ion Exchange Resins: Batch and Column Sorption-Elution Studies

In this research, the removal of boron and arsenic from geothermal water was examined by using novel N-methyl-d-glucamine functionalized gel-like resins (abbreviated as 1JW and 2JW) synthesized by the membrane emulsification method. The outcomes were compared with those of commercially available boron selective chelating ion exchange resin (Diaion CRB 05). According to the results obtained with the novel resins, it was possible to reduce both boron and arsenic concentrations in geothermal water by using these novel gel-like chelating resins below their permissible levels for agricultural irrigation (<1 mg B/L) and drinking water (<0.01 mg As/L) by using the batch method. The optimum resin concentration required for almost complete boron removal (more than 95%) with the two chelating resins was determined to be 2 g/L. The novel gel-like chelating resins 1JW and 2JW achieved 94% of arsenic removal by using the resin concentration of 8 g/L, while the required resin concentration was 32 g/L for 94% of arsenic removal using commercially available Diaion CRB05 resin. In addition, the column performance characteristics of the novel chelating resins for the separation of boron were studied, and the results were compared to those obtained with Diaion CRB05. According to the column data obtained, the total resin capacities of the Diaion CRB05, 1JW, and 2JW resins were calculated as 6.29, 5.08, and 4.64 mg B/mL-resin, respectively.

Large Scale Nationwide Screening of Bioavailable Tetracyclines and Arsenic Using Whole-cell Bioreporter from Pangasius and Tilapia Aquaculture System in Bangladesh

In this study, a large-scale screening of bioavailable tetracycline (TC) and arsenic (As) was carried out using Whole-Cell biosensor bacteria from the pond surface waters of selected pangasius and tilapia farms across Bangladesh. Bioavailability of Tetracyclines and Arsenic was detected using biosensor bacteria E. coli K12 pTetLux1 and E. coli DH5R (pJAMA-arsR), respectively. 62 samples were within the tetracycline detection limit; others were below the detection limit. The highest concentration 31.27µg/l was found in a pond of Jashore and the lowest concentration 2.57µg/l, was measured from Trishal, Mymensingh. Tetracyclines were detected in 19.57 % of all analyzed samples and varied from below the detection limit to a maximum of 31.27 μg/l. Khulna showed the maximum percentage of detected samples (90%), followed by Mymensingh (52%), Cumilla (27.5%), Jashore (14%), Bogura (14%), and Sathkhira (10%). Bioavailable As were detected in only 5.7% of all analyzed samples. Detectable as samples were higher in number among the collected samples at Madaripur and higher in percentage at Sathkhira (30%) followed by Madaripur (20%), Cumilla (5%), and Gopalgonj (3.2%). The pick level of Arsenic was found in Madaripur, which was 9.45 µg/l and the lowest figure was 2.35 µg/l, found in Cumilla. Though the concentrations of arsenic in groundwater (tube well water) were high in all studied regions, the concentrations of arsenic in pond water were low in every region. The concentration of as in the experimental ponds was neither very high nor in the danger limit. Use of shallow tube well water, fertilizers, drugs, pesticides, and herbicides possessed with as during fish culture might be the source of as contamination. However, extensive use of antibiotics results in the emergence and spread of antibiotic resistance in the aquatic environment.

Using an anti-fouling electro- (stainless-steel/ PVC) membrane reactor in electrocoagulation process for arsenic removal: Experimental study and mechanism development in multiphase media using CFD

The electrocoagulation (EC) method is an effective way to remove arsenic (As) from water. However, to obtain high-quality floc-free water, it needs further purification, and membrane processes can be used to achieve this goal, but fouling is their main problem. In this study, a PVC/stainless steel electro-conductive membrane was used as a cathode electrode, and the effects of voltage, current, and time on the reduction of membrane fouling and arsenic removal were investigated. By increasing the applied voltage, due to the increase of the repulsive force between the membrane and negatively charged arsenic particles, the percentage of arsenic removal increased. While increasing the current density, more coagulant materials were produced from the anode, and the rejection rate of arsenic also became higher. The optimal conditions for removing arsenic at 22 V, 0.2 A, and 50 min were obtained according to the box-Behnken design in deionized water. After the second one-hour cycle, the concentration of arsenic in the model water decreased by 99.6% and fell below the maximum permissible level. Additionally, increasing voltage and current reduces membrane fouling due to an increase in the repulsive force and formation of bubbles on the membrane surface, respectively. Also, the process modeling results, considering the adsorption mechanism and repulsive force, showed that at 0.2 and 0.32 amperages, the model follows the Freundlich and Langmuir isotherms better, respectively, and showed an accurate prediction of experimental outcomes. Furthermore, 3D process modeling results indicated the distribution of velocity, current, voltage, and concentration inside the reactor.

Understanding water characteristics and arsenic contamination of Lower Bakırçay Basin (LBB) and its coastal wetland (Western Turkiye): from Bergama (Pergamum) to Çandarlı (Elaia) by hydrogeochemical tools and stable isotope signatures.

Bakırçay Basin is one of the largest and most productive basins in Turkey in terms of geothermal energy, history, mining, agriculture, and tourism. In this study, the lower part of the Bakırçay Basin was extensively examined using hydrogeochemical tools, encompassing 27 different water sample points in the basin, in alignment with the United Nations' 2030 sustainable development goals that focus on access to safe drinking water for all and climate action for carbon emissions. From the higher zones of the basin towards the coastal wetland, EC values increase from 212 to 26500 µS/cm. Again in the same direction, water types are Ca-Mg-HCO3 in hilly areas and Na-Cl at the coastal wetland. Salt marshes, which are the silent heroes of carbon sequestration, are the most important element of the Bakırçay coastal wetland. Irrigation water evaluation has also been made for agriculture, which is widespread in the basin. Except for the salty waters in the wetland, waters are suitable for irrigation. A contamination investigation was conducted in the waters with the aim of clean drinking water. As and Mn contamination, which exceeds the standard values, has been detected in the Bakırçay river and its tributaries, especially from the mining sites in LBB. The arsenic content of water in the study area varies between 2 and 62.2 ppb. Additionally, the study identified As(III) species, which is 60 times more toxic than As(V), in the study area. Stable isotope values (δ18O and δD) of waters in the basin are from - 6.66 to 1.43‰ and - 36.4 to 5.8‰, respectively, and all waters are of meteoric origin. It is essential to emphasize the importance of controlling mining activities in the basin, halting the construction of the port that will destroy the carbon sequestration coastal wetland, and instead, transforming it into a recreation area, the significance of which is now understood during the COVID-19 pandemic.

Low-to-Moderate Arsenic Exposure and Urothelial Tract Cancers with a Long Latent Period of Follow-Up in an Arseniasis Area

BackgroundArsenic exposure can cause adverse health effects. The effects of long-term low-to-moderate exposure and methylations remain unclear.ObjectiveThis study aims to examine the association between low-to-moderate arsenic exposure and urothelial tract cancers while considering the effects of methylation capacity.MethodsIn this study, 5,811 participants were recruited from an arseniasis area in Taiwan for inorganic arsenic metabolite analysis. This follow-up study was conducted between August 1995 and December 2017. We identified 85 urothelial tract cancers in these participants, including 49 bladder and 36 upper urothelial tract cancer cases. A Cox proportional hazards model was employed.ResultsThe analyses revealed a significant association between concentrations of inorganic arsenic in water > 100 ug/L and bladder cancer occurrence, with a hazard ratio (HR) of 4.88 (95% CI 1.35–17.61). A monotonic trend was observed between concentrations of inorganic arsenic in water (from 0 to > 100 ug/L) and the incidence of urothelial tract cancer, including bladder cancer (p < 0.05) and upper urothelial tract cancers (p < 0.05). Participants with a lower primary methylation index or higher secondary methylation index had a prominent effect.ConclusionsRigorous regulations and active interventions should be considered for populations with susceptible characteristics.

Trace metal load of two urban wetlands with varied catchment activities in Ghana.

This study compared Lead (Pb), Chromium (Cr), Copper (Cu), Zinc (Zn), Mercury (Hg), Arsenic (As) and Cadmium (Cd) concentrations in sediment, water, and biota at Vaughan Dam which receives limited sewage effluent discharge from residential areas, and Korle Lagoon which receives industrial effluents, electronic waste, garages-spill oil and a host of others in addition to residential sewage effluent discharge. Samples were analyzed with Atomic Absorption Spectrometer. The results showed that concentrations of trace metals were generally higher in the sediment, water, and plants from the Korle Lagoon but only Cu in the sediment of Korle Lagoon showed a significantly high concentration. The similarities in the rank orders of the metal concentrations together with the dominance of Zn and Pb in most compartments of the wetlands indicated major differences did not exist in the contaminant input to the two wetlands except electronic waste recycling and disposal that resulted in significantly high copper concentrations in the sediment of Korle Lagoon. No evidence of biomagnification was determined along the food chains of the Vaughan Dam and the Korle Lagoon for all the metals studied.The Tilapia zilli from Vaughan Dam, the only biota that is regularly consumed from the wetlands, had Cr, Cu, Pb, Cd, Hg, and As concentrations above FAO/WHO permissible limits and therefore pose a health risk to consumers.

Towards an understanding of the factors controlling bacterial diversity and activity in semi-passive Fe: and As-oxidizing bioreactors treating arsenic-rich acid mine drainage.

Semi-passive bioreactors based on iron and arsenic oxidation and co-precipitation are promising for the treatment of As-rich acid mine drainages. However, their performance in the field remains variable and unpredictable. Two bioreactors filled with distinct biomass carriers (plastic or a mix of wood and pozzolana) were monitored during one year. We characterized the dynamic of the bacterial communities in these bioreactors, and explored the influence of environmental and operational drivers on their diversity and activity. Bacterial diversity was analyzed by 16S rRNA gene metabarcoding. The aioA genes and transcripts were quantified by qPCR and RT-qPCR. Bacterial communities were dominated by several iron-oxidizing genera. Shifts in the communities were attributed to operational and physiochemical parameters including the nature of the biomass carrier, the water pH, temperature, arsenic and iron concentrations. The bioreactor filled with wood and pozzolana showed a better resilience to disturbances, related to a higher bacterial alpha diversity. We evidenced for the first time aioA expression in a treatment system, associated with the presence of active Thiomonas spp. This confirmed the contribution of biological arsenite oxidation to arsenic removal. The resilience and the functional redundancy of the communities developed in the bioreactors conferred robustness and stability to the treatment systems.

Removal of arsenic from contaminated water: Phytoaccumulation and adsorbent-based removal by activated carbon prepared from Typha tripholia

Aim: To assess the phytoaccumulation efficiency of arsenic in different parts of Typha tripholia (cattail) grown in the natural habitat of a pond located in Rada village of Bijua block, district Lakhimpur Kheri (U.P.) and to develop an adsorbent based removal technology by activated carbon prepared from Typha tripholia (ACTT) using physical activation. Methodology: Phytoaccumulation of arsenic was studied in cattail plants. Rhizomes and leaves of plants were used to prepare activated carbon. The morphological characterization and surface structure were studied by using different modern techniques like Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), and Brunauer-Emmett- Teller (BET). The adsorption efficiency and removal of arsenic were studied by using different doses of ACTT, i.e., 0.5, 1.0, 1.5, 2.0, 2.5 g 100 m l-1 in the known solution of arsenate (30 ppb). Results: The arsenic concentration in pond water was 19 µg l-1, which was higher than the permissible limit (10 µg l-1) of WHO, while in the soil it was 123 µg kg-1. The maximum As concentration in the root was 360 µg kg-1, while in the stem and leaf, it was 20 µg kg-1 and 26 µg kg-1, respectively. Characteristics properties of ACTT showed amorphous nature and it contained 81.71 % carbon while other elements like oxygen (10.65 %), chloride (2.12 %) and potassium (5.52%) were also detected. The porosity of ACTT was 1.271 × 10-3 cc g-1 with pore volume 3.7 × 10-3 cc g-1, while the pore size, pore width, and pore diameter were 4.498 nm, 2.0208 nm and 4.498 nm, respectively. Removal of arsenic increased on increasing the dose of activated carbon, and the maximum adsorption (99.6%) was observed at 1.5 g 100-1 ml further it decreased. Interpretation: Thus, Typha tripholia may be used as phytoremediation, a plant-based green technology for the removal of As from contaminated water while ACTT acts as a good adsorbent for As, due to its large surface area and pore space and a high degree of surface reactivity. Key words: Arsenic removal, Activated carbon, Adsorption, Cattail, Phytoaccumulation