Distribution and chemical speciation of dissolved inorganic arsenic in the Yellow Sea and East China Sea

Distribution and chemical speciation of dissolved inorganic arsenic were examined in Yellow Sea and East China Sea. Results demonstrated that： （1） both As（Ⅲ） and As（Ⅴ） were detected, with As（V） dominated at 40% stations of surface water and 51% stations of bottom water; （2） influenced by the exchange of fresh and sea water, the type of surface sediment and the transport of various water masses, large values in surface water were observed along the coastal region and in the same latitude of Changjiang River Estuary and Hangzhou Bay, and in bottom water found in the southern area where the Taiwan Warm Current and Kuroshio Current influenced; （3） As（Ⅲ） behaved non-conservatively in Changjiang River Estuary. Man-derived inputs cause substantial positive deviation from the theoretical dilution. The negative correlation of As（Ⅴ） to salinity in surface water suggested that it behaved conservatively during the transportation along Changjiang River Estuary. While, the occurrence of As（Ⅴ） up to the linear fit in bottom water indicated the eventual transfer from dissolved phase to particulate phase, which was impossible to be determined without the knowledge of arsenic level and speciation in suspended particulate matter. Further study is needed on the arsenic source/sink relationships based on the distribution profiles.

Synthesis of a Novel Imidazole Ionic Liquid Modified Mesoporous Silica SBA15 for Selective Separation and Determination of Inorganic Arsenic in Rice

A novel 1-methylimidazole ionic liquid modified SBA15 mesoporous silica(1-MIIL@SBA15) was synthesized and applied to selective separation of inorganic arsenic(iAs) in rice by dispersive solid phase extraction(DSPE), followed by hydride generation-atomic fluorescence spectrometric(HG-AFS) quantification. The prepared sorbent was characterized by FTIR, FESEM, BET and Zeta potential. Key parameters of adsorption and desorption in DSPE were optimized using standard reference material 1568 b rice flour. Under optimal conditions, the limit of detection was 8.776 ng/kg, relative standard deviation was ≤2.0%, and recoveries of iAs were in the 92.3～94.4% range. This method was successfully applied to the determination of iAs in rice. Under acidic condition, the electrostatic interaction between the positively charged 1-MIIL@SBA15 and anionic iAs played an important role in selective iAs separation, rendering this method suitable for iAs analysis.

Effect of inorganic arsenic in paddy soil on the migration and transformation of selenium species in rice plants

Selenium(Se)in paddy rice is one of the significant sources of human Se nutrition.However,the effect of arsenic(As)pollution in soil on the translocation of Se species in rice plants is unclear.In this research,a pot experiment was designed to examine the effect of the addition of 50 mg As/kg soil as arsenite or arsenate on the migration of Se species from soil to indica Minghui 63 and Luyoumingzhan.The results showed that the antagonism between inorganic As and Se was closely related to the rice cultivar and Se oxidation state in soil.Relative to the standalone selenate treatment,arsenite significantly(p<0.05)decreased the accumulation of selenocystine,selenomethionine and selenate in the roots,stems,sheaths,leaves,brans and kernels of both cultivars by 21.4%-100.0%,40.0%-100.0%,41.0%-100%,5.4%-96.3%,11.3%-100.0% and 26.2%-39.7% respectively,except for selenocystine in the kernels of indica Minghui 63 and selenomethionine in the leaves of indica Minghui 63 and the stems of indica Luyoumingzhan.Arsenate also decreased(p<0.05)the accumulation of selenocystine,selenomethionine and selenate in the roots,stems,brans and kernels of both cultivars by 34.9%-100.0%,30.2%-100.0%,11.3%-100.0% and 5.6%-39.6%respectively,except for selenate in the stems of indica Minghui 63.However,relative to the standalone selenite treatment,arsenite and arsenate decreased(p<0.05)the accumulation of selenocystine,selenomethionine and selenite only in the roots of indica Minghui 63 by 45.5%-100.0%.Our results suggested that arsenite and arsenate had better antagonism toward Se species in selenate-added soil than that in selenite-added soil;moreover,arsenite had a higher inhibiting effect on the accumulation of Se species than arsenate.

A critical review of on-site inorganic arsenic screening methods

Approximately 94 to 220 million people worldwide are at risk of drinking well water containing arsenic > 10 μg/L, the WHO guideline value. To identify non-compliant domestic wells, assess health risks and reduce exposure, accurate and rapid on-site inorganic arsenic screening methods are desirable because all domestic wells worldwide need to be tested.Here, the principles, advantages and limitations of commonly used colorimetry, electrochemistry, and biosensing methods are critically reviewed, with the performance compared with laboratory-based benchmark methods. Most commercial kits are based on the classic Gutzeit reaction. Despite being semi-quantitative, the more recent and more expensive products display improved and acceptable accuracy and shorter testing time (~10 min). Carried out by trained professionals, electrochemical methods are also feasible for on-site analysis, although miniaturization is desirable yet challenging. Biosensing using whole bacterial cells or bio-engineered materials such as aptamers is promising, if incorporated with function specific nanomaterials and biomaterials. Since arsenic is frequently found as arsenite in reducing groundwater and subject to oxidation during sampling, transportation and storage, on-site separation and sample preservation are feasible but the specific methods should be chosen based on sample matrix and tested before use. To eliminate arsenic exposure among hundreds of millions of mostly rural residents worldwide, we call for concerted efforts in research community and regulatory authority to develop accurate, rapid, and affordable tests for on-site screening and monitoring of arsenic in drinking water. Access to affordable testing will benefit people who are socioeconomically disadvantaged.

Multiple transformation pathways of p-arsanilic acid to inorganic arsenic species in water during UV disinfection

p-Arsanilic acid（p-ASA） is widely used in China as livestock and poultry feed additive for promoting animal growth.The use of organoarsenics poses a potential threat to the environment because it is mostly excreted by animals in its original form and can be transformed by UV–Vis light excitation.This work examined the initial rate and efficiency of p-ASA phototransformation under UV-C disinfection lamp.Several factors influencing p-ASA phototransformation,namely,p H,initial concentration,temperature,as well as the presence of Na Cl,NH4＋,and humic acid,were investigated.Quenching experiments and LC–MS were performed to investigate the mechanism of p-ASA phototransformation.Results show that p-ASA was decomposed to inorganic arsenic（including As（Ⅲ） and As（V））and aromatic products by UV-C light through direct photolysis and indirect oxidation.The oxidation efficency of p-ASA by direct photosis was about 32%,and those by HOU and1O2 were 19% and 49%,respectively.Cleavage of the arsenic–benzene bond through direct photolysis,HOU oxidation or1O2 oxidation results in simultaneous formation of inorganic As（Ⅲ）,As（IV）,and As（V）.Inorganic As（Ⅲ） is oxidized to As（IV） and then to As（V） by1O2 or HOU.As（IV） can undergo dismutation or simply react with oxygen to produce As（V） as well.Reactions of the organic moieties of p-ASA produce aniline,aminophenol and azobenzene derivatives as main products.The photoconvertible property of p-ASA implies that UV disinfection of wastewaters from poultry and swine farms containing p-ASA poses a potential threat to the ecosystem,especially agricultural environments.

Increased PIT1 and PIT2 Expression in Streptozotocin (STZ)-induced Diabetic Mice Contributes to Uptake of iAs^((V))

Objective This study aimed to investigate the susceptibility of mice with streptozotocin（STZ）-induced diabetes mellitus（TIDM） to the uptake of pentavalent inorganic arsenic（iAs^V） and the possible molecular mechanism. Methods TIDM was induced in mice by STZ. TIDM and normal mice were treated with 15.0 mg/kg Na2HAsO4·12H2O by intragastric administration. Then, the concentrations of arsenic in various tissues were measured by atomic fluorescence spectrometry. The gene expression levels of Pit1 and Pit2 were quantified by real-time RT-PCR, and their protein levels were detected by Western blotting in mouse heart, kidney, and liver tissues. Results The concentrations of arsenic in STZ-induced TIDM mouse tissues were higher at 2 h after intragastric administration of Na2HAsO4·12H2O. Compared with the levels in normal mice, PIT1 and PIT2, which play a role in the uptake of iAs^V, were upregulated in the livers and hearts of TIDM mice. PIT1 but not PIT2 was higher in TIDM mouse kidneys. The upregulation of Pit1 and Pit2 expression could be reversed by insulin treatment. Conclusion The increased uptake of iAs^V in TIDM mouse tissues may be associated with increased PIT1 and/or PIT2 expression.

A comprehensive study of treatment of arsenic in water combining oxidation,coagulation,and filtration

Arsenic is one of the most common inorganic contaminants in groundwater worldwide,mainly due to the release of naturally occurring arsenic from aquifer sediments（Amini et al.,2008;Li and Cai,2015;Rahman et al.,2015）.Naturally occurring arsenic exists predominantly in arsenate and arsenite species in groundwater.