Effect Of Arsenic Concentration Research Articles

Determination of Arsenic Uptake Potential in An Edible Plant Species (Trigonellna foenum- granecum) and Assessment of Human Health Risk

Arsenic is a carcinogenic and toxic element that possesses a high health risk from its presence in crops, water, and soil. The present study has been conducted by fenugreek (Trigonella foenum-granecum) seeds which is a very common spice used for cooking, especially in India. An equal number of seeds have been germinated in laboratory conditions. Three concentrations e.g. 1, 2, and, 3 mg/L of arsenite (As+3) and arsenate (As+5) salt solutions were used throughout the experiments for the treatment of plants. After 10 days of germination, the concentration of the arsenic accumulated into the plant edible parts was estimated and health risk was assessed. Effects of arsenic concentration were observed through estimating the total chlorophyll (a, b, c), carotenoid content, and taking the fresh weight and dry weight of both the control and treatment plants. The results of the biochemical analysis revealed that chlorophyll and carotenoid contents were decreased than that of control plants. Moreover, fresh weight and dry weight results also showed lower values in treatments than in controls. The bioaccumulation factor results demonstrated that an increased level of soil arsenic doesn’t certainly result in high arsenic uptake by the Fenugreek plants. From the concentration estimated in the plant body, the health risk was assessed in adults and children and found that both adults and children having a potential health risk upon consumption of fenugreek. Moreover, Incremental Life Time Cancer Risk was found high (< 10-4) which indicates the presence of potential cancer risk. Hence, it is possible to conclude from the present study that fenugreek can bio-accumulate arsenic and it may be used as an indicator plant for arsenic-contaminated areas.

Kinetics of arsenic absorption by the species Eichhornia crassipes and Lemna valdiviana under optimized conditions

This work aimed to study the kinetics of arsenic absorption by Eichhornia crassipes and Lemna valdiviana under pre-established conditions of pH phosphate and nitrate in the nutrient solution. Additional aims were to evaluate the conversion kinetics between As(III) and As(V), and the effect of arsenic concentrations on development of the species. The plants were cultivated in nutrient solutions containing different arsenic concentrations: 0, 0.56, 0.89 and 1.38 mg L−1 for the water-hyacinth, and 0, 0.13, 0.48, 0.99 and 1.4 mg L−1 for Lemna. Monitoring of arsenic removal by the plants was performed by sampling at intervals of 0, 4, 8, 16, 24, 48, 96, 144, 192 and 240 h for the water hyacinth, and 0, 4, 8, 16, 24, 48, 96, 144 and 168 h for Lemna. The samples were submitted to analysis of total arsenic, As(III), As(V) and phosphorus. The first-order kinetics was fit to the arsenic removal kinetics by the plants, and it was observed that the decay coefficient (k) decreased with the increase of its initial concentration in the nutrient solution. For the, absorption was observed after 96 h of culture, the time coinciding with the greatest As(V) concentrations. For Lemna, the metal was only absorbed by the plant after decay of the phosphate levels of the medium, which occurred at 48 h. Concentrations above 1 mg L−1 implied deleterious effects in both plant species and in the phytoremediation process, and the bioaccumulation factor decreased for concentration above this for both E. crassipes and L. valdiviana.

Effect of Arsenic Concentrations in Soil on Growth and Arsenic Accumulation of Pteris multifida

Effect of Arsenic Concentrations in Soil on Growth and Arsenic Accumulation of Pteris multifida

Nature and reactivity of layered double hydroxides formed by coprecipitating Mg, Al and As(V): Effect of arsenic concentration, pH, and aging

Arsenic (As) co-precipitation is one of the major processes controlling As solubility in soils and waters. When As is co-precipitated with Al and Mg, the possible formation of layered double hydroxides (LDHs) and other nanocomposites can stabilize As in their structures thus making this toxic element less available. We investigated the nature and reactivity of Mg–Al–arsenate [As(V)] co-precipitated LDHs formed in solution affected by As concentration, pH, and aging. At the beginning of the co-precipitation process, poorly crystalline LDH and non-crystalline Al(Mg)-oxides form. Prolonged aging of the samples promotes crystallization of LDHs, evidenced by an increase in As K XANES intensities and XRD peak intensities. During aging Al- and/or Mg-oxides are likely transformed by dissolution/re-precipitation processes into more crystalline but still defective LDHs. Surface area, chemical composition, reactivity of the precipitates, and anion exchange properties of As(V) in the co-precipitates are influenced by pH, aging, and As concentration. This study demonstrates that (i) As(V) retards or inhibits the formation and transformation of LDHs and (ii) more As(V) is removed from solution if co-precipitated with Mg and Al than by sorption onto well crystallized LDHs.

Effect of Arsenic Concentration in Irrigation Water and Soil on the Arsenic Content of Vegetables in Bangladesh

Two pot experiments were conducted to examine the effect of arsenic (As) concentration both in irrigation water and in soil on the As content in vegetables grown in a glass greenhouse. In the first experiment, spinach (Spinacia oleracea), green amaranth (Amaranthus viridis) and gima kalmi (Ipomoea aquatica) were grown in soil containing 10 mgAskg, where the irrigation water contained two As levels (0.1 and 0.5 mg L). In the second experiment, gima kalmi (Ipomoea aquatica) was grown in As spiked soil at different levels [10 (control), 15, 20, 30, and 50 mgAskg soil] and with irrigation water without As contamination. The As concentration (mg kg DW) and As accumulation (μg plant) in the edible part of the plants increased significantly with increasing As concentrations in irrigation water and/or soil. When plants were irrigated with As contaminated water, the As concentration of the edible part exceeded its maximum limit Original Research Article Joardar et al.; IJPSS, Article no. IJPSS.2014.007 86 (0.5 mg kg) in spinach and green amaranth at 0.5 mg L of As, but gima kalmi had a smaller amount than the other vegetables. Gima kalmi had the characteristics of a lower As accumulation. Therefore, the risk level of As in irrigation water was suggested to be 0.1 mg L for vegetables. When gima kalmi was grown in elevated levels of As contaminated soil, the As concentration of gima kalmi, even being a low As accumulator, exceeded the maximum limit at the level above 20 mgAskg soil. The risk level of As in soil, therefore, was suggested to be 20 mg kg. The risk value of As concentration in irrigation water and/or in soil needs to be investigated in detail by using many vegetables and/or soils.

Arsenic (V) removal from groundwater by GE-HL nanofiltration membrane: effects of arsenic concentration, pH, and co-existing ions

A laboratory-scale investigation was performed to study arsenic (As (V)) removal by negatively charged GE-HL nanofiltration (NF) membrane in simulated drinking water. Effects of As (V) concentration (0–200 μg·L−1), pH, and co-ions and counter-ions were investigated. The NF membrane presented good stability, and the rejection rates exceeded 90%. The rejection rates of As (V) decreased with the increase of As (V) concentration, while it increased with the increase of pH (reached 96% at pH 6.75). Moreover, a negative relationship was observed between the co-existing ions of Cl−, Na+, SO42−, and Ca2+ and the removal of As (V), in which bivalent ions presented more significant effects than monovalent ions.

Effect of arsenic concentration on microbial iron reduction and arsenic speciation in an iron-rich freshwater sediment

Depth profiles in the sediment porewaters of the Chattahoochee River (Georgia, USA) show that iron oxides scavenge arsenate in the water column and settle to the sediment–water interface (SWI) where they are reduced by iron-reducing bacteria. During their reduction, these particles seem to release arsenic to the porewaters in the form of arsenate only. Sediment slurry incubations were conducted to determine the effect of low concentrations of arsenic (⩽10 μM) on biogeochemical processes in these sediments. Experiments confirm that any arsenate (As(V)) added to these sediments is immediately adsorbed in oxic conditions and released in anoxic conditions during the microbial reduction of authigenic iron oxides. Incubations in the presence of ⩽1 μM As(V) reveal that arsenate is released but not concomitantly reduced during this process. Simultaneously, microbial iron reduction is enhanced significantly, spurring the simultaneous release of arsenate into porewaters and secondary formation of crystalline iron oxides. Above 1 μM As(V), however, the microbial reductive dissolution of iron oxides appears inhibited by arsenate, and arsenite is produced in excess in the porewaters. These incubations show that even low inputs of arsenic to riverine sediments may affect microbial processes, the stability of iron oxides and, indirectly, the cycling of arsenic. Possible mechanisms for such effects on iron reduction are proposed.

Effects of zinc, copper and sodium ions on ferric arsenate precipitation in a novel atmospheric scorodite process

A novel process has been developed for the fixation of arsenic using the formation of scorodite. Stable scorodite particles were produced by introducing an oxidizing gas into a reaction mixture containing ferrous sulfate and arsenic(V) at high concentration to convert the ferrous ion to ferric ion. This approach to scorodite synthesis enabled the reaction to proceed in the presence of sulfuric acid under atmospheric pressure. The influence of zinc, copper, and sodium ions in the solution was investigated; as well as the effect of pure O 2 gas and air as the oxidizing agent and the effect of arsenic concentration and pH of the reaction mixture. Scorodite grains were precipitated even though the reaction system contained co-existing ions at high concentration. It was found that zinc did not affect the synthesis and that the presence of copper yielded a good scorodite product. However, the presence of sodium inhibited the formation of scorodite. An initial pH under 2 was significant for producing well-crystallized scorodite and avoiding conditions favorable for jarosite formation.

Experimental and modelling analysis of As(V) ions adsorption on granular activated carbon

In this work the adsorption of pentavalent arsenic on a granular activated carbon (GAC) has been experimentally studied. The effects of arsenic concentration, pH, temperature and salinity on equilibrium adsorption capacity have been investigated. Experimental results show that the adsorption capacity is the highest at neutral pH conditions, low salinity levels and high temperatures. A model for the description of the arsenic adsorption mechanism is reported. This is based on the multicomponent Langmuir adsorption theory applied to the ionic species in solution. The model points out that the adsorption capacity is proportional to the concentration of arsenic anions in solution and decreases by increasing the concentration of competitive ions such as hydroxides and chlorides, allowing a correct interpretation of the pH and salinity effects on the adsorption capacity. Finally, one of the main goals of the proposed model is to preserve the exothermicity of the adsorption phenomena despite the observed trend of experimental results: the increase of adsorption capacity with temperature appears to be related to a higher arsenic dissociation.

Arsenic speciation and transport in Pteris vittata L. and the effects on phosphorus in the xylem sap

The mechanism of arsenic (As) transport in Pteris vittata L. (Chinese brake fern), the first known arsenic-hyperaccumulating plant, is important to understand how arsenic is detoxified in the fern. The effects of arsenic concentration and form on arsenic and phosphorus in xylem sap were investigated using hydroponics systems. Ferns were subjected to 0, 10 or 50 mg As l −1 as As(III), As(V), DMA or MMA. Xylem sap was collected and analyzed for arsenic concentration and speciation and inorganic phosphorus concentrations. When arsenic was supplied as an inorganic form, As(V), was the predominant form transported in the sap. This may be due to its resemblance to phosphorus. However, when arsenic was supplied in the methylated form, the fern transported the arsenic mainly in the form supplied. The presence of arsenic in the xylem sap did not significantly affect the inorganic phosphorus concentration in the sap. Regardless of the species supplied, arsenic may be transported in the form(s) which are least harmful to the plant. The fact that arsenic was stored mostly as As(III) in the pinnae of the frond but transported as As(V) or methylated forms indicates the majority of the arsenic reduction takes place in the frond pinnae.

Effects of Arsenic Concentrations and Forms on Arsenic Uptake by the Hyperaccumulator Ladder Brake

Ladder brake (Pteris vittata L.) is a newly discovered arsenic hyperaccumulator. No information is available about arsenic effects on ladder brake. This study determined the effects of different arsenic concentrations (50 to 1000 mg kg(-1)) or forms (organic vs. inorganic and arsenite vs. arsenate) applied to soils on growth and arsenic uptake by ladder brake. Young plants were grown in a greenhouse for 12 or 18 wk. Ladder brake was highly tolerant of arsenic and survived in soil containing up to 500 mg As kg(-1). The fact that addition of arsenate up to 100 mg As kg(-1) increased fern biomass by 64 to 107%, coupled with higher arsenic concentration in younger fronds at low soil arsenic concentrations and older fronds at high soil arsenic concentrations, implies that arsenic may be beneficial for fern growth. Addition of 50 mg As kg(-1) was best for fern growth and arsenic accumulation, resulting in the highest fern biomass (3.9 g plant(-1)), bioconcentration factor (up to 63), and translocation factor (up to 25). With an exception of FeAsO4 and AlAsO4, which had the lowest effects due to their low solubility, little difference was observed among other arsenic forms mainly because of arsenic conversion in soil. Aboveground biomass was mostly responsible for accumulation of arsenic by plant (75-99%). Up to 26% of the added arsenic was removed by ladder brake, showing the high efficiency of ladder brake in arsenic removal. The results suggest that ladder brake may be a good candidate to remediate arsenic-contaminated soils.

Effects of Arsenic Concentrations and Forms on Arsenic Uptake by the Hyperaccumulator Ladder Brake

Ladder brake (Pteris vittata L.) is a newly discovered arsenic hyperaccumulator. No information is available about arsenic effects on ladder brake. This study determined the effects of different arsenic concentrations (50 to 1000 mg kg−1) or forms (organic vs. inorganic and arsenite vs. arsenate) applied to soils on growth and arsenic uptake by ladder brake. Young plants were grown in a greenhouse for 12 or 18 wk. Ladder brake was highly tolerant of arsenic and survived in soil containing up to 500 mg As kg−1 The fact that addition of arsenate up to 100 mg As kg−1 increased fern biomass by 64 to 107%, coupled with higher arsenic concentration in younger fronds at low soil arsenic concentrations and older fronds at high soil arsenic concentrations, implies that arsenic may be beneficial for fern growth. Addition of 50 mg As kg−1 was best for fern growth and arsenic accumulation, resulting in the highest fern biomass (3.9 g plant−1), bioconcentration factor (up to 63), and translocation factor (up to 25). With an exception of FeAsO4 and AlAsO4, which had the lowest effects due to their low solubility, little difference was observed among other arsenic forms mainly because of arsenic conversion in soil. Aboveground biomass was mostly responsible for accumulation of arsenic by plant (75–99%). Up to 26% of the added arsenic was removed by ladder brake, showing the high efficiency of ladder brake in arsenic removal. The results suggest that ladder brake may be a good candidate to remediate arsenic-contaminated soils.

Effects of arsenic concentration on the formation of dislocation loops near the projected ion range in high-dose As+-implanted (001) Si

The formation of a two-layer structure and the inhibition of the formation of dislocation loops near the projected ion range (Rp ) have been observed by cross-sectional transmission electron microscopy in 80 keV, 1×1016 and 2×1016/cm2 As+-implanted (001) Si, respectively. The correlations among the arsenic concentration, electrical inactivation of impurity, suppression of the formation of interstitial loops near Rp, and retardation of the epitaxial regrowth rate provide significant insight into the point-defect migration and agglomeration during solid phase epitaxial regrowth of implantation amorphous silicon.

The ion-exchange behaviour of arsenic(III) on varion anion-exchange resins

The ion-exchange equilibrium of arsenic ions was studied on the strongly basic anion-exchange resins VARION AD, VARION AT-4 and VARION AT-6. The apparent equilibrium constants ( K x ) and the distribution coefficients ( D) were determined between the resin and the liquid phases in acidic and alkaline solutions. The effect of arsenic concentration on the course of chromatographic experiments was studied in terms of the breakthrough capacity of the ion-exchange column and the pH of the effluent. VARION AT-6 resin proved to be the most suitable for removing arsenic from highly alkaline solution.