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• Species of inorganic As and Se in coal, fly ash and gypsum were analysed by HPLC-ICP-MS. • AsV was the dominating species in coal and fly ash extracts. • AsIII, much more toxic than AsV, was mainly detected in gypsum samples. • Se was mostly present as SeIV in fly ash and gypsum extracts. This study investigated arsenic (As) and selenium (Se) distribution and speciation in coal and the burning by-products (fly ash and gypsum) in five coal-fired power plants in China. Total concentrations of As and Se in coal varied significantly among different power plants, but most of them were below the average As and Se content in Chinese coal. The concentrations of As and Se in fly ash were much higher than that in coal. Total As contents in four gypsum samples were lower than that in coal, while Se contents in four gypsum samples were much higher than that in coal. The species of inorganic As (AsIII and AsV) and Se (SeIV and SeVI) were determined by high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry after solvent extraction. The extraction efficiencies of As and Se in coal were low, but a considerable amount of As and Se in fly ash and gypsum can be extracted, showing that elements As and Se were easily leached from the burning by-products. Speciation analysis indicated that Se was mostly present as SeIV in all the fly ash and gypsum extracts, and AsV was the dominating species in coal and fly ash extracts. In contrast, AsIII, much more toxic than AsV, was mainly detected in gypsum. Large amounts of coal-fired by-products are produced every year, most of which end up in landfills or stockpiled in the open areas. Our results suggest that the proper disposal of coal-fired solid wastes is urgently demanded. [ABSTRACT FROM AUTHOR]

Coal-Gas replacement project has been implemented to decrease haze pollution in China in recent years. Airborne arsenic (As) mostly originates from coal burning processes. It is noteworthy to compare the distribution of arsenic fraction in PM 2.5 before and after coal-gas replacement. Eighty PM 2.5 samples were collected in Baoding in December 2016 (coal dominated year) and December 2017 (gas dominated year) at different functional areas including residential area (RA), industrial area (IA), suburb (SB), roadside (ST) and Botanical Garden Park (BG). The fraction, bioavailability and health risk of As in the PM 2.5 samples were investigated and compared between these two years. Arsenic was mainly distributed in the non-specifically sorbed fraction (F1) and the residual fraction (F5). However, the proportion of F1 to the total As in 2017 was higher than that in 2016, while the proportion of As in the amorphous and poorly-crystalline hydrous oxides of Fe and Al fraction (F3) in 2017 was lower. The distributions of fraction and bioavailability showed temporal and spatial characteristics. The total concentration and bioavailability of As in SB and IA were significantly higher than those in RA, ST and BG. The BF (Bioavailability Factor) values of As ranged from 0.30 to 0.61. Health risk assessment indicated that the hazard quotient (HQ) and carcinogenic risk (CR) of As in PM 2.5 significantly decreased after coal-gas replacement. Image 1 • Concentration of As in PM 2.5 decreased after coal limiting. • Fraction distribution was different in the samples from different functional areas. • Health risk was significantly decreased (p < 0.05) after Coal-Gas replacement. The concentration of arsenic in PM 2.5 and health risks decreased after coal-gas replacement implementation. [ABSTRACT FROM AUTHOR]

The distribution and chemical speciation of arsenic (As) in different sized atmospheric particulate matters (PMs), including total suspended particles (TSP), PM 10 , and PM 2.5 , collected from Baoding, China were analyzed. The average total mass concentrations of As in TSP, PM 10 , and PM 2.5 were 31.5, 35.3, and 54.1 µg/g, respectively, with an order of PM 2.5 >PM 10 > TSP, revealing that As is prone to accumulate on fine particles. Due to the divergent toxicities of different As species, speciation analysis of As in PMs is further conducted. Most of previous studies mainly focused on inorganic arsenite (iAs III ), inorganic arsenate (iAs V ), monomethylarsonate (MMA), and dimethylarsinate (DMA) in PMs, while the identification and sensitive quantification of trimethylarsine oxide (TMAO) were rarely reported. In this study, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs. An anion exchange column was used to separate MMA, DMA and iAs V , while a cation exchange column to separate TMAO and iAs III . Results showed that iAs V was the dominate component in all the samples, corresponding to a portion of 79.2% ± 9.3% of the total extractable species, while iAs III , TMAO and DMA made up the remaining 21%. Our study demonstrated that iAs III accounted for about 14.4% ± 11.4% of the total extracted species, with an average concentration of 1.7 ± 1.6 ng/m 3 . It is worth noting that TMAO was widely present in the samples (84 out of 97 samples), which supported the assumption that TMAO was ubiquitous in atmospheric particles., (Copyright © 2021. Published by Elsevier B.V.)

Coal-Gas replacement project has been implemented to decrease haze pollution in China in recent years. Airborne arsenic (As) mostly originates from coal burning processes. It is noteworthy to compare the distribution of arsenic fraction in PM 2.5 before and after coal-gas replacement. Eighty PM 2.5 samples were collected in Baoding in December 2016 (coal dominated year) and December 2017 (gas dominated year) at different functional areas including residential area (RA), industrial area (IA), suburb (SB), roadside (ST) and Botanical Garden Park (BG). The fraction, bioavailability and health risk of As in the PM 2.5 samples were investigated and compared between these two years. Arsenic was mainly distributed in the non-specifically sorbed fraction (F1) and the residual fraction (F5). However, the proportion of F1 to the total As in 2017 was higher than that in 2016, while the proportion of As in the amorphous and poorly-crystalline hydrous oxides of Fe and Al fraction (F3) in 2017 was lower. The distributions of fraction and bioavailability showed temporal and spatial characteristics. The total concentration and bioavailability of As in SB and IA were significantly higher than those in RA, ST and BG. The BF (Bioavailability Factor) values of As ranged from 0.30 to 0.61. Health risk assessment indicated that the hazard quotient (HQ) and carcinogenic risk (CR) of As in PM 2.5 significantly decreased after coal-gas replacement., Competing Interests: Declaration of competing interest All authors (Jiao-Jiao Xie, Chun-Gang Yuan, Jin Xie, Xiao-Dong Niu, Xu-Rui Zhang, Ke-Gang Zhang, Pei-Yao Xu, Xiao-Ying Ma, Xiang-Bin Lv) have seen and approved the submission of the manuscript. The authors declared that there is no conflict of intrest. We also affirm that this manuscript is not under consideration for publication and has not been published elsewhere in any medium including electronic journals and computer databases of a public nature. We assure you that there are no related works that are currently under consideration for publication in this or other journals., (Copyright © 2020 Elsevier Ltd. All rights reserved.)