Comparison of arsenic geochemical evolution in the Datong Basin (Shanxi) and Hetao Basin (Inner Mongolia), China

Shi

Jiang

et al. 2013

Environ. Sci. Technol.

Self Cite

Chronic exposure to arsenic (As) threatens human health. To systematically understand the health risks induced by As ingestion, we explored water and diet contributions to As exposure, and compared As in biomarkers and the arsenicosis in a geogenic As area in China. In this study, high percentages of water (77% of n = 131 total samples), vegetables (92%, n = 120), cereals (32%, n = 25), urine (70%, n = 99), nails (76%, n = 176), and hair (62%, n = 61) contained As higher than the acceptable levels. Dietary As contributed 92% of the average daily dose (ADD) when the water As concentration was less than 10 μg/L, for which 5 out of 30 examined participants were diagnosed with arsenicosis symptoms. The distinct positive correlation between ADD and As concentrations in urine, nails, and hair suggests different applicability for these biomarkers. Methylated As as the predominant urinary As species confirms that the ingested inorganic As is methylated and is excreted through urine. In situ microdistribution and speciation analysis indicates that As is mainly associated with sulfur in nails and hair. Nails, rather than hair and urine, could be used as a proper biomarker for arsenicosis. High ADD from the environment and low excretion could result in As toxicity to humans. ■ INTRODUCTIONArsenic (As) poses a severe threat to human health through exposure pathways mainly including water and diet. 1,2 Drinking water with elevated As levels is the primary source of As ingestion. 1,3 Moreover, As-laden groundwater, if used for irrigation, can lead to appreciable amounts of As accumulation in vegetables and cereals. 4−6 Extensive research demonstrates that rice and rice products could be another As source. 7,8 However, not much attention has been paid to other cereals like wheat, which are important staple foods worldwide, that could lead to significant As ingestion. 9 The intake of As results in its detection in noninvasive human biomarkers such as urine, nails, and hair. 10−12 Urine has frequently been used as a biomarker for short-term exposure because most As metabolites are excreted within 3−4 days through urine. 12,13 Nails and hair indicate long-term exposure for 2−12 months, 10 as As can be accumulated in these structures rich in keratin. 14 Thus, the association of As levels in biomarkers and groundwater has been recently studied to evaluate its health risks. 11,15 The speciation of As in biomarkers is crucial to understand the transformation, metabolism, and toxicity of ingested As. 12,16 As species in hair and nails are traditionally determined by chemical extraction, where inorganic and methylated As are detected. 14,17 No As−S species have been reported using indirect chemical extraction methods, even though As readily bonds to sulphydryl groups. 14 In contrast, As−S species have been detected in nail and hair samples using in situ X-ray absorption near-edge structure (XANES) spectroscopy. 15 Unfortunately, methylated As species are not distinguished from the As−S form in nails, 18 which deserves further...

Section: ■ Materials and Methodsmentioning

confidence: 99%

Arsenic Levels and Speciation from Ingestion Exposures to Biomarkers in Shanxi, China: Implications for Human Health

Shi

Jiang

et al. 2013

Environ. Sci. Technol.

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“…S1). Very few studies employed high groundwater As levels (∼500 to ∼1000 μg/L) (Luo et al 2012;, which could rapidly saturate the capacity of adsorbents (Kanematsu et al 2012;Li et al 2012). Second, systematic study on the influence of variation of empty bed contact time (EBCT) has been limited, though EBCT can regulate As breakthrough curves (Zeng et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Groundwater arsenic removal using granular TiO2: integrated laboratory and field study

et al. 2014

Environ Sci Pollut Res

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High concentrations of arsenic (As) in groundwater pose a great threat to human health. The motivation of this study was to provide a practical solution for As-safe water in As geogenic areas using granular TiO 2 (GTiO 2 ). The kinetics results indicated that the As (III/V) adsorption on GTiO 2 conformed to the Weber-Morris (WM) intraparticle diffusion model. The Langmuir isotherm results suggested that the adsorption capacities for As (III) and As (V) were 106.4 and 38.3 mg/g, respectively. Ion effect study showed that cationic Ca and Mg substantially enhanced As (V) adsorption, whereas no significant impact was observed on As (III). Silicate substantially decreased As (V) adsorption by 57 % and As (III) by 50 %. HCO 3 − remarkably inhibited As (V) adsorption by 52 %, whereas it slightly reduced As (III) adsorption by 8 %. Field column results demonstrated that ∼700 μg/L As was removed at an empty bed contact time (EBCT) of 1.08 min for 968 bed volumes before effluent As concentration exceeded 10 μg/L, corresponding to 0.96 mg As/g GTiO 2 . Two household filters loaded with 110 g GTiO 2 in the on-off operational mode can provide 6-L/day As-safe drinking water up to 288 and 600 days from the groundwater containing ∼700 μg/L As and ∼217 μg/L As, respectively. Integration of batch experiments and column tests with systematic variation of EBCTs was successfully achieved using PHREEQC incorporating a charge distribution multisite complexation (CD-MUSIC) model and one-dimensional reactive transport block.

“…S5, ESI †), which is in accordance with our previous report. 15 The As concentration was obtained using the linear regression equation in Fig. 2.…”

mentioning

confidence: 99%

Rapid in situ identification of arsenic species using a portable Fe₃O₄@Ag SERS sensor

Jing

2014

Chem. Commun.

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Rapid and sensitive SERS identification and quantification of arsenic species in multiple matrices have been realized using a Fe 3 O 4 @Ag magnetic substrate. The molecular structure of arsenic on Fe 3 O 4 @Ag characterized using EXAFS spectroscopy and DFT confirms the existence of a chemical effect on SERS enhancement.Arsenic (As) contamination is a pressing environmental issue that causes serious threat to human health. 1 The presence of As has been well documented in multiple environmental matrices including groundwater, soil and sediment, and foods. 2 The toxicity and mobility of As depend on its oxidation state, where arsenite (As(III)) is 50-100 times more toxic than arsenate (As(V)). 1 As speciation analysis is usually achieved by separation using high performance liquid chromatography combined with mass spectrometry or atomic absorption/ fluorescence spectrometry. These techniques require samples to be collected and transported to the laboratory, which may induce As(III) oxidation, and thus lead to biased conclusions on its toxicity. Therefore, the need for rapid and sensitive field As speciation analysis has motivated great research efforts for decades. 3 Recently, As field testing kits were developed, but failed in a high fraction of cases when analyzing groundwater samples. 4,5 Nevertheless, most current field detection methods are not capable of As speciation analysis. 6 Surface enhanced Raman scattering (SERS) spectroscopy provides an alternative tool for fast screening of As-contaminated environmental samples. Previous studies proved that silver (Ag) substrates can achieve SERS sensing of 10 mg L À1 As(III) and As(V). 6-9 However, the Ag SERS substrate was susceptible to matrix effects, and could not even detect 10 mg L À1 As(V) in a spiked groundwater sample. 10 Therefore, either complicated pretreatment or a standard addition method is needed to compensate for the reduced SERS sensitivity in real environmental matrices. 6,10 The lack of reliable in situ methodology has prevented wide application of the SERS technique. Herein, we present a portable SERS sensor for onsite monitoring of arsenic speciation. Fe 3 O 4 @Ag core-shell magnetic NPs, which are capable of fast preconcentration, rapid separation, and exhibit high SERS sensitivity, were used as reliable SERS substrates for determination of As(III) and As(V). The entire process can be completed within 2 min. Moreover, the active SERS substrate can be used for As sensing in complex media such as juice, wine, and soils.The detailed synthetic procedure for Fe 3 O 4 @Ag NPs is described in the ESI. † The morphology and structure of Fe 3 O 4 @Ag were characterized by transmission electron microscopy (TEM) and high-resolution (HR) TEM. A 10 nm Ag layer was coated on the 70 AE 20 nm Fe 3 O 4