Arsenic in the Environment

Bhattacharya, Prosun; Jacks, Gunnar; Frisbie, Seth H.; Smith, Euan; Naidu, R. L.; Sarkar, Bibudhendra

doi:10.1201/9780203909300.ch6

Cited by 119 publications

(95 citation statements)

References 114 publications

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“…The background As concentration in soils is controlled by the lithology of the parent rocks (Yan Chu, 1994) and it is important to assess this in a given area prior to remediation. In view of the potential risk of bioaccumulation and toxicity of As (Bhumbla and Keefer, 1994;Bhattacharya et al, 1997Bhattacharya et al, , 2001), the geochemical behaviour of As in nature has generated much concern in environmental research in recent years. Under the range of Eh and pH in soil compartments, As normally occurs in qIII and qV oxidation states (Cullen and Reimer, 1989 under oxidising conditions (peqpH)8) (Sadiq et al, 1983;Masscheleyn et al, 1991).…”

Section: Chemistry Of Cca Metals In Soilsmentioning

confidence: 99%

Metal contamination at a wood preservation site: characterisation and experimental studies on remediation

Bhattacharya

Mukherjee

Jacks

et al. 2002

The Science of The Total Environment

107

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The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil. The mean As content of the contaminated surface soils (0-10 cm) was 186 mg kg , where as the mean concentrations of Cu, Cr y1 and Zn in soils from the contaminated area were 26, 29 and 91 mg kg , respectively. The elevated As content in y1 the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions. Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area. The fine fraction of the soil (-0.125 mm) has an average metal content increased by nearly 34% as compared to the -2-mm fraction conventionally used for the analysis and assessment of soil contamination. The -2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (-0.125 mm) constitutes approximately 10%. These facts, taken together, are essential for the choice of remediation measures. Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al-and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species. Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites. With a three-step sequential leaching, up to 98-99% of the metals could be removed. At lower concentrations and higher pH, the leaching decreased to approximately 70%. ᮊ

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Section: Chemistry Of Cca Metals In Soilsmentioning

confidence: 99%

Metal contamination at a wood preservation site: characterisation and experimental studies on remediation

Bhattacharya

Mukherjee

Jacks

et al. 2002

The Science of The Total Environment

107

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“…For preparing ICS, a FeCl 3 solution (100 mL, 0.1 M), adjusted to pH 4, 7, or 10 with 0.1 M HNO 3 or NaOH, was mixed with raw sand (100 g) in a rotary evaporator for 2 h. For MCS, a Mn(NO 3 ) 2 solution (100 mL, 0.1 M), previously adjusted to pH 4, 7 or 10, was mixed with raw sand (100 g) in the rotary evaporator. For IMCS, FeCl 3 (50 mL, 0.1 M) and Mn(NO 3 ) 2 (50 mL, 0.1 M) solutions, previously adjusted to pH 4, were mixed at different ratios with raw sand (100 g) in the rotary evaporator.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…In each experiment, the desired mass of precipitator was mixed with 500 mL of 2 mg/L phosphate. The solution pH was adjusted over the reaction time using 0.01 M HNO 3 and NaOH. The solution was mixed at 30 rpm for 24 h.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…2 Arsenic contamination in groundwater is a worldwide concern because the metal may have severe adverse effects on human and ecological receptors. 3 Primary potable water supplies are contaminated in many rural areas and developing countries like Bangladesh, India, and Nepal, where the arsenic level has remained at 50 μg/L. 4,5 Bangladesh is in a severe situation, with 35−77 million of its citizens potentially exposed to water with arsenic levels above the recommended limit of the World Health Organization (WHO), which is 10 μg/L.…”

Section: ■ Introductionmentioning

confidence: 99%

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Removal of Arsenic and Phosphate from Aqueous Solution by Metal (Hydr-)oxide Coated Sand

Huang

Yang

Keller

2014

ACS Sustainable Chem. Eng.

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Arsenic contamination is a major concern in many drinking water supplies around the world. One low-cost approach for removing arsenic and other oxyanions such as phosphate is to use metal (hydro-)oxide coated sands. In this study, solution pH, sand grain size, coating efficiency, and mineral type for iron-coated sand (ICS), manganese-coated sand (MCS), and iron-and manganese-coated sand (IMCS) were evaluated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used to investigate the surface properties of the coated layer. The mineral type of ICS prepared at different solution pH was identified as a mixture of FeOOH and Fe 2 O 3 . The mineral type of MCS prepared at pH 4 and 7 was identified as MnO 2 and changed to ramsdellite (γ-MnO 2 , a mixture of α-MnO 2 and β-MnO 2 ) at pH 10. ICS exhibited a greater phosphate removal capacity, and phosphate removal increased with increasing iron oxide on the sand. ICS was also shown to have a greater removal capacity for phosphate than chemical precipitation methods by FeCl 3 , especially below neutral pH. In contrast, IMCS(Fe:Mn = 7:3) was better for removing As(III), which occurs through oxidation to As(V) and adsorption of As(III) and As(V) and can reach >98% removal rate (residual concentration <0.02 mg/L) at neutral pH. IMCS(7:3) is an efficient adsorbent for arsenic, as >50% can be removed within 60 min; 66% adsorption was reached after 24 h. Removal of arsenic and phosphate by these metal (hydro-)oxide coated sand adsorbents followed a pseudo-second-order rate and Langmuir as well as Freundlich adsorption isotherms. Removal under different conditions (e.g., pH, ionic strength) was also evaluated to provide information to optimize the process.

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“…Bacterial As(III) oxidase genes are phylogenetically diverse and ecologically widespread [85]. Microbial oxidation of As(III) to As(V) occur under both aerobic and anaerobic soil conditions, which significantly enhance the immobilization of As in the soils, due to the fact that As(V) can more easily co-precipitate with ferric iron or be adsorbed by ferrihydrite [86]. In the rhizosphere soil, it remains unclear whether the activity of As(III) oxidizing bacteria (expression of aroA-like gene [85]) is elevated by the root exudates or the oxygen released from the rice roots to result in more As(V) binding on iron minerals in soil and iron plaque on rice roots, thus to reduce the bioavailability of As to rice roots.…”

Section: Interactions Of Microorganisms With Iron Oxidesmentioning

confidence: 99%

Effects of microbial processes on the fate of arsenic in paddy soil

2012

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Arsenic (As) is a metalloid toxic to organisms including humans. Arsenic in rice represents a significant exposure pathway for the general population, particularly for those subsisting on rice. Arsenic transformation, namely reduction, oxidation and methylation, in soil-rice systems has fundamental impacts on its mobility and toxicity. In addition to soil chemical properties (pH, Eh, metallic oxides, organic matter), microorganisms play critical roles in As transformation and mobility in paddy soil, such as through ArsM (As(III) S-adenosylmethyltransferase) and interactions with iron oxides or organic matters. Arsenic species in paddy soil directly influence As speciation in rice grain because the methylated As species in rice are mainly derived from microbial methylation in paddy soil. This paper aims to provide an overview on the status of the knowledge and gaps on the chemical aspects of As transformation in soil-rice system in conjunction with microbial ecology and functional genes. In addition, potential pathways (manipulation of microorganisms in paddy soil and genetic engineering) to decrease total As and/or inorganic As in rice grain are proposed.

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Arsenic in the Environment

Cited by 119 publications

References 114 publications

Metal contamination at a wood preservation site: characterisation and experimental studies on remediation

Metal contamination at a wood preservation site: characterisation and experimental studies on remediation

Removal of Arsenic and Phosphate from Aqueous Solution by Metal (Hydr-)oxide Coated Sand

Effects of microbial processes on the fate of arsenic in paddy soil

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