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In aim to study the influence of circulating ash used as heat carrier and dolomite used as catalyst on mercury transition during the step conversion of coal pyrolysis and combustion, five experiments with different operating conditions were conducted in this study, including four pyrolysis experiments of raw coal, coal/ash, coal/dolomite, coal and ash/dolomite, and combustion experiment of pyrolysis solid product. By changing the experimental conditions including final pyrolysis temperature, heating rate, coal-ash ratio and dolomite type, the transition path and final mercury distribution in the step conversion process were comprehensively analyzed. Experiments results indicated that mercury completely released out from coal when the final pyrolysis temperature was 600 °C. The individual addition of ash could promote the mercury release from coal at lower temperature. Dolomite could catalyze the oxidation of Hg0 in gas phase, and the modified dolomite had better catalytic capacity for Hg0 oxidation than natural dolomite. The addition of circulating ash and natural dolomite both had a certain catalytic effect on Hg0 emission peaks during the coal pyrolysis. Increasing the coal-ash ratio was conducive to the oxidation of Hg0 in pyrolysis gas. During the direct combustion of coal, the content of Hg0 released into the gas phase could reach to 69.97%. By adding ash, ash/natural dolomite and ash/modified dolomite to the coal pyrolysis process, the content of Hg0 in pyrolysis gas decreased to 58.99%, 34.77% and 31.30%, respectively. The research is able to offer the theoretical foundation for mercury contaminants' removal and process optimization of the step conversion technology. • Ash heat carrier can promote the release of mercury in coal at lower temperatures. • Fe 2 O 3 has the strongest catalysis ability towards Hg0. • Dolomite and circulating ash have a synergistic effect on Hg0 oxidation. • The step conversion process greatly reduces the treatment pressure of mercury. [ABSTRACT FROM AUTHOR]

Highlights • Complexation of Hg with the antibiotics resulting in the dissolution of Hg compounds from the sediment. • Hg ions in the sediment can also promote the degradation of antibiotics. • The degradation of TC/OTC radicals generates CH3+ groups which can react with Hg° to form MeHg. Abstract The role of antibiotics commonly used in fish culture activities in methylmercury (MeHg) formation in mariculture sediments (MS) and in reference sediments (RS) was studied using simulation microcosms. MS and RS were split into three equal batches. Two batches were spiked with Hg(NO 3) 2 aqueous solution at levels of 2 and 8 mg kg−1 (dry weight basis) and the remainder served as a control batch. Tetracycline (TC) and oxytetracycline (OTC) (2.5 g and 10 g of each) were added to each treatment. Sediment THg concentration decreased during the culture period possibly due to complexation of Hg with the antibiotics resulting in the dissolution of Hg compounds from the sediment. More importantly, the MeHg concentration increased after 32 days together with a decrease in the concentrations of the antibiotics in the sediment. The complexation of TC or OTC with Hg resulted in the transport of electrons from TC or OTC to Hg2+ due to the high electronegativity of Hg2+. Subsequently, Hg2+ was reduced to Hg° which reacted with CH 3 + derived from TC or OTC. The use of antibiotics may therefore promote the formation of MeHg in sediments. [ABSTRACT FROM AUTHOR]

A simulative mesocosm study was conducted to evaluate the influence of wet–dry rotation on mercury (Hg) flux from soil/water to air and the distribution of Hg species in water as well as Hg chemical fractions in soil. Three types of soil were employed including two kinds of paddy soil, Typic Purpli-Udic Cambosols (TPUC) and Xanthi-Udic Ferralosols (XUF), as well as the Alluvial Soil (AS) from Three Gorge reservoir area in Chongqing, China. The results showed that Hg fluxes in wetting periods were significantly higher than that in drying periods. It might be due to the formation of a layer of stable air over the water surface in which some redox reactions promote evasion processes over the water surface. This result indicated that more Hg would be evaporated from the Three Gorge reservoir and paddy soil field during the flooding season. Hg fluxes were positively correlated with air temperature and solar irradiation, while negatively correlated with air humidity and the electronic conductivity of water. Hg fluxes from AS and TPUC were significantly higher than that from XUF, which might be due to the higher organic matter (OM) contents in XUF than TPUC and AS. The reduction processes of oxidized Hg were restrained due to the strong binding of Hg to OM, resulting in the decrease in Hg flux from the soil. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg2+ on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl2 complexes in solution. Moreover, Cl− inhibited the Hg2+ adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg2+ adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg2+ and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg2+ adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl− and HA, and therefore the reducing of Cl− promoted more Hg2+ on Fe and Mn hydroxides. In addition, the influence of HA on Hg2+ adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides. [Copyright &y& Elsevier]

Abstract: This study investigated total mercury (THg) and methylmercury (MeHg) concentrations in five species of freshwater fish and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The concentrations of THg and MeHg in fish pond surface sediments were 33.1–386ngg−1 dry wt and 0.18–1.25ngg−1 dry wt, respectively. The age of ponds affected the surface sediment MeHg concentration. The vertical distribution of MeHg in sediment cores showed that MeHg concentrations decreased with increasing depth in the top 10cm. In addition, a significant correlation was observed between %MeHg and DNA from Desulfovibrionacaea or Desulfobulbus (p <0.05) in sediment cores. Concentrations of THg and MeHg in fish muscles ranged from 7.43–76.7 to 5.93–76.1ngg−1 wet wt, respectively, with significant linear relationships (r =0.97, p <0.01, n =122) observed between THg and MeHg levels in fish. A significant correlation between THg concentrations in fish (herbivorous: r =0.71, p <0.05, n =7; carnivorous: r =0.77, p <0.05, n =11) and corresponding sediments was also obtained. Risk assessment indicated that the consumption of largemouth bass and mandarin fish would result in higher estimated daily intakes (EDIs) of MeHg than reference dose (RfD) for both adults and children. [Copyright &y& Elsevier]

Co-pyrolysis of coal and seaweed can not only effectively decrease the carbon footprint but also improve the quality and output of coal pyrolysis products, however, the influence of seaweed on thermal releasing behaviors of mercury during co-pyrolysis process are still unclear. In this work, the chlorella and Guizhou bituminous coal were mixed and used to reveal the mercury release behavior during co-pyrolysis by the temperature programmed pyrolysis experiments, thermogravimetric and differential thermogravimetric analysis (TG-DTG) and thermogravimetry-mass spectrometry (TG-MS) methods, offering a sufficient explanation on the control technology of mercury pollutants in co-pyrolysis. The results exhibited that a large amount of reducing gases such as CO, H 2 and H 2 O were generated in chlorella at the temperature range of 100-500°C, which was favorable for the transformation from oxidized mercury to elemental mercury, thus remarkably increased the release of elemental mercury in the raw coal sample. The mixed chlorella also significantly lowered the decomposition temperature range (from 400-600 to 300-400°C) of pyrite-bound mercury and decreased the decomposition temperatures of the pyrite-bound mercury species. Additionally, in the co-pyrolysis about 91.82% of mercury was released into the gas phase below 400°C and was 13.77% higher than that of in individual pyrolysis of coal. [Display omitted] [ABSTRACT FROM AUTHOR]

Consumption of fish and aquatic products is considered to be the main pathway of human exposure to methylmercury (MeHg). To assess human health risk through seafood consumption in a coastal area of Guangdong Province, South China, a total of 518 seafood samples (including fish, shrimp, crabs, and mollusks) were collected from 11 coastal cities for total mercury (THg) analysis. The THg concentrations varied significantly among different seafood groups and ranged from 0.11 to 317 ng/g (with a mean of 37.2 ng/g). The THg concentrations were relatively low compared with fish from Europe and North America, and no samples exceeded the national limit recommended by the Standardization Administration of China (0.5 ng/g wet wt). The ecological functional groups and cultured styles have significant effects on THg concentrations in the fish tissue. The median of probable daily intakes (PDIs) of MeHg via seafood consumption ranged from 42.6 to 71.4 ng/g for different age groups, with fish contributing the major portion (84%). The results indicated potential health risks associated with seafood consumption for the general population in the coastal area of Guangdong Province, South China. Environ. Toxicol. Chem. 2013;32:541-547. © 2012 SETAC [ABSTRACT FROM AUTHOR]

• Mercury occurrence and thermal stability in high ash bituminous coal were determined. • The relations of Hg content with organic sulfur, sulfate and sulfide were obtained. • Mercury species in various density fractions were quite distinct. • The matrix-bound Hg, HCl soluble Hg, HgS and Hg(NO 3) 2 ·xH 2 O were thermally unstable and released before 400 °C. • The pyrite-bound Hg mainly enriched in density >2.0 g/cm3 fraction and released at 400–600 °C. The high-ash coals have gradually become essential energy resources due to their availability, and the occurrence of Hg in coals and its thermal stability could be significantly influenced by ash-forming minerals. In this work, a high-ash bituminous coal was divided into 4 density fractions using sink-float procedure. The sequential chemical extraction procedures, temperature-programmed pyrolysis and TG/DTG experiments were carried to investigate the Hg occurrence and thermal stability in different samples. The results showed that the Hg contents in samples has a positive relation with the ash, sulfate and sulfide contents, and the correlation coefficients were 0.868, 0.535 and 0.924, respectively. However, the negative value with correlation coefficient of 0.751 between the Hg and organic sulfur content was obtained. The Hg species in different samples were quite distinct, the organic matrix-bound Hg was the dominate form in SG1 with the content of 76.14%, the SG2 and SG3 were mainly composed of HCl soluble Hg and Hg(NO 3) 2 ·xH 2 O, and the Hg species occurred in SG4 were mainly HCl soluble Hg and pyrite-bound Hg. In the process of pyrolysis, the matrix-bound Hg, HCl soluble Hg, HgS and Hg(NO 3) 2 ·xH 2 O were thermally unstable and could be released into gas in the drying and desorption stage of 30–400 °C, while the pyrite-bound Hg mainly released with the decomposition of pyrite in the temperature range of 400–600 °C. There was only little Hg released in the temperature range of 600–850 °C, indicating the negligible relationship of Hg with carbonate and silicate minerals. [ABSTRACT FROM AUTHOR]

In this study, bacterial mercury (Hg) methylation was investigated under the influence of red-tide algae of Skeletonema costatum (S. costatum). The distribution and speciation of total mercury (THg) and methylmercury (MeHg) were profiled by employing Geobacter metallireducens (G. metallireducens GS-15) as the methylating bacteria. G. metallireducens GS-15 showed different capabilities in methylating different inorganic forms of Hg(II) (HgCl 2) and Hg(II)-Algae (HgCl 2 captured by S. costatum) to MeHg. In the absence of S. costatum , a maximum methylation efficiency of 4.31 ± 0.47% was achieved with Hg(II) of 1–100 μg L−1, while accelerated MeHg formation rate was detected at a higher initial Hg(II) concentration. In the presence of S. costatum , there were distinct changes in the distribution of THg and MeHg by altering the bioavailability of Hg(II) and Hg(II)-Algae. A larger proportion of THg tended to be retained by a higher algal biomass, resulting in decreased methylation efficiencies. The methylation efficiency of Hg(II) decreased from 3.01 ± 0.10% to 1.01 ± 0.01% with 10-mL and 250-mL algal media, and that of Hg(II)-Algae decreased from 0.83 ± 0.13% to 0.22 ± 0.01% with 10-mL and 250-mL Hg(II)-Algae media. Fourier transform infrared spectrometry, surface charge properties and elemental compositions of S. costatum were used to infer that amine, carboxyl and sulfonate functional groups were most likely to interact with Hg(II) through complexation and/or electrostatic attraction. These results suggest that red-tide algae may be an influencing factor on bacterial Hg methylation in eutrophic water bodies. Unlabelled Image • Bacterial Hg methylation was investigated in the Hg-algae-bacteria system. • Bacterial MeHg yield and methylation efficiency depended on algal biomass. • Higher algal biomass reduced the potential risk of bacterial Hg methylation. • S. costatum exerted significant influences on Hg distribution and speciation. • Various functional groups in algal cells were involved in Hg-algae interactions. [ABSTRACT FROM AUTHOR]

• The 3D structure carbon aerogel with highly dispersed SnO 2 nanoparticles was synthesized. • The sorbent exhibited high Hg0 and H 2 S capture capacities and excellent regeneration performance. • The core-shell structure is beneficial for the resistance to H 2 O. • E-R adsorption mechanism of H 2 S and Hg0 was conformed. A seaweed-templated pathway was developed for the controllable synthesis of SnO 2 /carbon aerogel for the simultaneous removal of Hg0 and H 2 S in natural gases, where the SnO 2 nanoparticles with an outer diameter of 4–20 nm were highly dispersed and conjoined by graphitic carbon, forming a 3D core-shell structure with a developed pore network. The synthesized sorbent performed a complete removal of Hg0 and H 2 S at a high space velocity of 70,000 h−1 and showed resistance to water. At 5% breakthrough, the Hg0 and H 2 S capture capacities reached as high as 10.37 mg g−1 and 392.23 mg g−1, respectively, which are much higher than those of the existing commercial sorbents. More importantly, the spent sorbent could be easily regenerated without significant performance degradation over five cycles. The 3D interconnected macro- and mesopores are beneficial for the Hg0 and H 2 S removal at a high space velocity, and the core-shell structure is conducive to prevent poisoning from water. The Hg0 and H 2 S removal over the SnO 2 /aerogel conforms to the E-R mechanism, where H 2 S is first adsorbed and dissociated on the SnO 2 surface to produce active sulfur species, and the adsorbed sulfur then reacts with gaseous Hg0 to form HgS. [ABSTRACT FROM AUTHOR]

Abstract The multistep solvent extraction is an effective way for evaluating the original structure of coal, however, it is seldom used for studying the Hg distribution in coal and its release behavior during mild pyrolysis process. In this work, the Guizhou bituminous coal was divided into organic-rich class C 1 and minerals-rich class C 2 , the C 1 was further subdivided into 4 groups (EG 1 –EG 4) using multistep solvent extraction method. The Hg species in different samples and their fate during pyrolysis was investigated using sequential chemical leaching methods and temperature-programmed experiments. The results showed the dominant Hg forms in different samples are quite different, the HCl-soluble and HNO 3 -soluble Hg are the dominant forms in C 2 , while organic matrix combined Hg is the most abundant form in C 1 , EG 1 and EG 2 samples. The Hg contents in EG 1 to EG 4 groups are in the order of EG 4 < EG 3 < EG 2 < EG 1 , and have little correlation with the total sulfur contents. The thermal stability of different Hg species are quite distinct, the Hg in EG 1 sample is the most thermal unstable and almost released completely before 400 °C. The Hg release of GZB, C 1 , and C 2 are similar, >60% and 95% of Hg in the three samples can be released at 400 °C and 600 °C, respectively. The Hg-OM+ combined with aromatic clusters in EG 2 is difficult to decompose during pyrolysis process, it mainly released in the temperature range of 400–800 °C. Except the Hg-OM+ combined with aromatic clusters in EG 2 , >95% of Hg can be released before 600 °C for other samples. When the heating rate increased from 5 °C/min to 20 °C/min, the Hg releasing peaks ranged from 150 to 400 °C shifted gradually to higher temperature zones, but there was no obvious change in the positions of peaks ranged from 400 to 800 °C. Graphical abstract Unlabelled Image Highlights • The Hg distribution and releasing behavior in samples were investigated by using multistep solvent extraction method. • The Hg contents in EG 1 to EG 4 samples have little correlation with the total sulfur contents. • The Hg species and their thermal stability in different samples are quite distinct. • More than 95% of Hg in raw coal can be released before 600 °C. • The Hg-OM+ combined with aromatic clusters in EG 2 has higher releasing temperature than other Hg species. [ABSTRACT FROM AUTHOR]

Abstract Algae and mercury (Hg) are ubiquitous in marine environments. In this study, we investigated the effects of a typical marine algae of diatom Skeletonema costatum on Hg methylation by an iron-reducing bacterium of Geobacter sulfurreducens (G. sulfurreducens) PCA. In the absence of Skeletonema costatum , the bacterial MeHg production rate maximized at 104.06 ± 11.7 ng L−1 h−1 with a high Hg level, while the highest methylation efficiency was achieved at a low Hg concentration. The existence of Skeletonema costatum greatly inhibited the capability of G. sulfurreducens PCA to methylate Hg. With the increase in algal biomass, there was a significant mitigation of MeHg formation and Hg0 release, leaving a considerable proportion of immobilized Hg2+ species (up to 47%) associated with algal cell materials. These results suggest that marine algae are crucial in determining the bioavailability of Hg contaminants and the methylating potential of G. sulfurreducens PCA. Highlights • Marine algae of Skeletonema costatum was insignificant in Hg methylation. • G. Sulfurreducens PCA was capable of bacterial methylation of Hg. • Bacterial methylation depended on initial Hg level and active algal biomass. • Bacterial methylation of Hg was inhibited by Skeletonema costatum. • Algal biomass was crucial in determining the distribution and transformation of Hg. [ABSTRACT FROM AUTHOR]

The silver loaded adsorbents has been demonstrated to be an exciting approach towards Hg 0 removal from natural gas streams, its Hg 0 removal efficiency and capacity is closely related to the valence state, particle size and dispersity of silver particles. This study focused on chemical reduction methods in aqueous solutions to synthesize Ag/4A zeolite, and the influences of ultrasonic and protective additives were investigated to reduce the size of silver particles. The characterization results showed that silver particles are loaded on the surface of 4A zeolite with highly dispersed elemental form, ultrasonic and addition of stearic acid as protective additives are the effective ways to produce small nano-scale silver particles close to 15 nm. Meanwhile, the silver particles on the surface of Ag/4A zeolite are the active sites for Hg 0 adsorption which can react with Hg 0 to form Ag-Hg amalgam alloy. The silver lattices disappeared from the outer boundary to the interior of the particles after Hg 0 adsorption, which indicated that the Hg 0 firstly reacts with the nano-scale silver on the surfaces and then gradually penetrates into the interior of silver particles. The Hg 0 removal efficiency of prepared Ag/4A zeolite adsorbents was higher than 96% after 200 min adsorption at 30 °C, and adsorption capacity reached to 5.985 mg/g. Furthermore, the regeneration and reutilization results indicated that the Hg 0 adsorption performance remained stable after 5 reuse cycles. [ABSTRACT FROM AUTHOR]

In this study, a green synthesis route was developed to prepare Ca and Co oxides supported carbon aerogel from renewable alginate. The sodium alginate was adopted as a template and carbon source, and a hydrogel with a three-dimensional and core-shell structure was chelated by introducing calcium and cobalt bimetals. The synthesized Ca Co oxides supported carbon aerogel can completely remove Hg0 in the HCl-containing waste gasification gas at room temperature. The Hg0 adsorption capacity on the 4Ca-1Co/CA adsorbent is as high as 4.02 mg/g when the 5% breakthrough occurs. At a 20% breakthrough of HCl, the captured amount of HCl could reach 175.37 mg/g. We concluded that the introduction of calcium and cobalt on the adsorbent provides sufficient active sites for the removal of HCl in a large amount, at the same time, the excellent oxygen supply capacity of Co species in an oxygen-free atmosphere can form active chlorine sites, which is conductive to enhance the removal of Hg0. Additionally, the 4Ca-1Co/CA adsorbent has the characteristics of wide temperature window and wide application range of space velocity, which can meet the needs of various working conditions. [Display omitted] • A green synthesis route to prepare Ca and Co oxides supported carbon aerogel from renewable alginate is provided. • There is a synergistic effect on removing HCl and Hg0 at 4Ca-1Co/CA adsorbent. • The introduction of Ca and Co provides sufficient active sites for the highly efficient removal of HCl and Hg0. • A wide temperature window and high space velocity could be performed on 4Ca-1Co/CA adsorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel sorbent was prepared for simultaneous removal of H 2 S and Hg0 in natural gas. • H 2 S and Hg0 capacities of 1Cu1Zn/SBA-15 were 296.78 mg·g−1 and 12.75 mg·g−1 at 10% breakthrough. • The 1Cu1Zn/SBA-15 sorbent exhibited excellent the regeneration performance over 5 cycles. • the S n 2− formed by chemisorption of H 2 S are the active sites for Hg0 capture. Inspired by the fact that H 2 S can easily decompose on some metal oxides to form sulfur species and the resulting products are usually used as Hg0 removal active sites, a novel Cu-Zn mixed oxide supported SBA-15 zeolite was controllably synthesized for simultaneous removal of Hg0 and H 2 S. The Cu-Zn nanoparticles with a particle size range of 4.4–5.0 nm were successfully confined and uniformly dispersed in the two-dimensional mesopores of SBA-15. The obtained 1Cu1Zn/SBA-15 adsorbent presented an outstanding H 2 S and Hg0 removal efficiencies at 30 °C and 30,000 h−1, and the H 2 S and Hg0 capture capacities reached to 296.78 mg·g−1 and 12.75 mg·g−1 at a 10% breakthrough. In addition, the spent adsorbent could be regenerated in a 5% O 2 and 95% N 2 atmosphere at 600 °C without obvious degradation of adsorption capacities over five cycles. We considered that the doping effects of Cu-Zn oxides were beneficial for its excellent H 2 S and Hg0 removal performance at low temperatures, and the nano-confinement effect of SBA-15 was conducive to prevent the oxides nanoparticles from agglomeration in the regeneration process, thus achieving the outstanding regeneration performance. Furthermore, the polysulfide polymer formed by chemisorption of H 2 S on the Cu-Zn oxides surface was confirmed to be the Hg0 active sites, which could react with gaseous mercury to form HgS. This work provided an effective way for simultaneous removal of H 2 S and Hg0 in natural gas by confining nano-sized active metal oxides into the mesopores of zeolites. [ABSTRACT FROM AUTHOR]

Abstract: Emissions of mercury (Hg) to air have regional and global impacts through long range transport in the atmosphere. Primary Zn production is regarded as an important anthropogenic Hg source in China, but research on its Hg emission is limited. To gain a better understanding of Hg emissions from Zn production activities in China, field investigations at four industrial-scale Zn production plants using electrostatic process with Hg removal (HP-WR), electrostatic process without Hg removal (HP-WOR), retort Zn production (RZ), imperial smelting process (ISP), and one artisanal Zn smelting process (AZ) were carried out. In the investigation, Hg emission factors are defined as how much Hg was emitted to the atmosphere per ton Zn produced during various Zn production methods and were estimated by using mass balance method. The results showed that the estimated Hg emission factors of Zn production were 5.7±4.0g Hg t− 1 Zn for HP-WR, 31±22g Hg t− 1 Zn for HP-WOR, 34±71g Hg t− 1 Zn for RZ, 122±122g Hg t− 1 Zn g t− 1 for ISP, and 75±115g Hg t− 1 Zn for AZ. Approximately 80.7–104.2 t year− 1 of Hg was emitted to atmosphere from primary Zn production during the period of 2002–2006 in China. [ABSTRACT FROM AUTHOR]

Abstract: Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the Tongren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg mining. Mine waste contained high T-Hg concentrations, ranging from 1.8 to 900mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirming that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the binding and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varying from 92 to 2300ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg mining in the study area, but the extent of Hg contamination is dependent on the mining history and the scale of artisanal Hg mining. [Copyright &y& Elsevier]

• The Au/MCM-48 absorbent was controllable synthesized for Hg0 removal in natural gas. • Ultrafine Au nanoparticles were embedded in the three-dimensional channels of MCM-48. • The Au/MCM-48 absorbent exhibited excellent tolerance for H 2 O and H 2 S. • The Hg0 adsorption capacity of Au/MCM-48 is up to 7.23 mg∙g−1 at 5% breakthough. • The spent absorbent could be regenerated without distinct degradation over 5 cycles. The H 2 O and H 2 S in natural gas are frequently deemed to have inhibitory influences on Hg0 removal performance of most noble metal based Hg0 absorbents, it is extremely significant to develop an efficient and regenerable Hg0 removal absorbent with excellent H 2 S and H 2 O tolerance. In the work, the Au/MCM-48 absorbent was controllable synthesized using a facile yet robust method for Hg0 removal in H 2 S and H 2 O containing natural gas. The ultrafine Au nanoparticles with a diameter of 1.4 nm were embedded and uniformly dispersed in the three-dimensional channels of MCM-48. The absorbent of 1 wt% Au achieved a complete Hg0 capture performance at 60,000 h−1 and 30 °C by forming Au-Hg amalgam, and its Hg0 adsorption capacity achieved to 7.23 mg∙g−1 at 5% breakthrough. The spent sample could be easily regenerated by thermal treatment without distinct degradation over 5 cycles. The introduction of H 2 S and H 2 O in gas flow had an inappreciable impact on Hg0 removal performance over the Au/MCM-48 absorbent. The excellent Hg0 adsorption efficiency, outstanding capture capacity and good regeneration performance of the absorbent due to the nano-confinement of MCM-48 channels, which prevents Au nanoparticles from growing and agglomerating. Excellent H 2 O tolerance is attributed to the good hydrophobicity of MCM-48 modified by trimethylchlorosilane, and the high H 2 S tolerance is due to the fact that the Au nanoparticles lack reactivity toward H 2 S. This work provides a promising method for the preparation of effective and regenerable absorbents for demercuration in H 2 S and H 2 O containing natural gas. [ABSTRACT FROM AUTHOR]

• The rod-like MnO 2 catalyst modified by Co-Ce oxide were controllable synthesized. • The doping amount of Co influenced the enhancement of catalytic performance. • The prepared catalyst exhibited long-term stability and excellent SO 2 tolerance. • The addition of Co prevented the active sites from being poisoned by SO 2. The Co was firstly used as a dopant to improve the NO and Hg0 removal performance of CeO 2 loaded rod-like MnO 2 catalyst (Ce/MnO 2) and its SO 2 resistance. The results showed the doping process effectively improved the relative concentrations of chemisorbed oxygen as well as the contents of surface Ce4+ and Mn4+, enhanced the redox ability of catalyst, which was conducive to the simultaneous removal performance of NO and Hg0 in flue gas. The Co-Ce/MnO 2 catalyst (the mole ratio of Co/Ce = 1.0) had optimal catalytic performance among all prepared catalysts in 160–280 °C, its NO and Hg0 removal efficiencies achieved 99.9% and 91.9% at 200 °C and 10,000 h−1, respectively. In addition, the Co-Ce/MnO 2 performed stronger resistance to SO 2 in comparison with Ce/MnO 2 , its catalytic activities decreased slightly when SO 2 with a concentration of 500 ppm was added into the gas stream, and then recovered close to the initial value after eliminating of SO 2. We considered the excellent SO 2 tolerance performance of Co-Ce/MnO 2 catalyst is assigned to the fact that the Co-modification restrained the sulfation of CeO 2 and MnO 2 to CeSO 4 and MnSO 4 , alleviated the decreasing of chemisorbed oxygen, and hindered the chemisorption of SO 2 on the catalyst. This work provided a promising prospect of Co-modification on Ce/MnO 2 as SO 2 resistant catalysts for simultaneous removal of NO and Hg0 from flue gas. [ABSTRACT FROM AUTHOR]

Changes in the biogeochemical cycling of mercury (Hg) and Hg species were investigated in a typical marine aquaculture area located at Zhoushan island, Zhejiang province, east China. Mercury species were analyzed in different environmental samples collected during a field survey and a simulation batch experiment. The field work comprised both summer and winter collection of water and sediment samples from marine aquaculture sites (MAS) in a field survey and from corresponding reference sites (CRS) located 2500 m from the MAS. THg concentrations in water were 91.3 ± 70.3 and 115 ± 22.6 pmol L−1 in summer and winter, respectively. Particulate Hg accounting for ˃60% of THg and positively correlated with total suspended solid content in water. Dissolved organic carbon in water was positively correlated with dissolved Hg. Significantly higher (p < 0.001, F = 102) total methylmercury (TMeHg) contents were observed in MAS (0.31 ± 0.26 ng g−1) than in CRS (0.06 ± 0.03 ng g−1) in the sediment solid phase. Moreover, MeHg formation rate in MAS was clearly higher than in CRS in the simulation experiment. Both the field survey and the simulation experiment highlighted the readier formation of MeHg in MAS than in CRS. TMeHg levels in blackhead seabream (Acanthopagrus schlegelii), red snapper (Lutjanus campechanus) and perch (Perca fluviatilis) were only 52.7 ± 5.74, 23.7 ± 2.51 and 24.3 ± 3.86 ng g−1, values significantly lower than the safety guideline (1000 ng g−1) established by the World Health Organization. Unlabelled Image • THg concentration in water was 91.3 pmol·L−1 and PHg account for 63.4% of THg. • Fish farming increased THg accumulation and MeHg formation in sediment. • Suspended solid influence the Hg distribution and sedimentation in water. • MeHg concentration in fish tissues was significantly lower than WHO guidelines. [ABSTRACT FROM AUTHOR]

• A regenerable and H 2 S resistance Hg0 removal sorbent was synthesized using fulvic acid. • The Ag nanoparticles were confined and embedded in the carbon nanosheets. • The special core-shell structure of Ag/Fvs is beneficial for the tolerance to H 2 S. • The nanoconfinement of carbon layer is conducive to regeneration performance. The migration and agglomeration of Ag nanoparticles during high temperature regeneration processes were generally considered the key contributor for the decreasing of Hg0 removal performance over Ag-based sorbents. In this work, a complexation pathway was developed for controllable synthesis of Ag loaded carbon nanosheet (Ag/Fvs) using fulvic acid as template and carbon source. The elemental Ag nanoparticles were highly dispersed and embedded in the carbon nanosheet with an average diameter of 7.12 nm and formed a special core-shell structure. The synthesized sorbent achieved a complete Hg0 removal in H 2 S containing natural gas at ambient temperature. At 1% breakthrough, the Hg0 capture capacity of Ag/Fvs was as high as 1.36 mg·g−1, which is much higher than the sample prepared by traditional impregnation method (I-Ag/Fvs, 0.98 mg·g−1) and other existing commercial sorbents. More importantly, the spent Ag/Fvs could be easily regenerated by thermal treating process, its Hg0 capture capacity only slightly decreased by 5.8% after 4 cycles. We considered the carbon layer prevented Ag nanoparticles from poisoning by H 2 S, and more active sulfur sites for Hg0 capture could be formed on porous carbon nanosheets by chemical adsorption of H 2 S, which is beneficial for the strong tolerance to H 2 S. The excellent regeneration performance of Ag/Fvs mainly attributed to the nanoconfinement of carbon layer, which is conducive to prevent the agglomeration of Ag nanoparticles during high temperature regeneration processes. This work represented a practical and efficient pathway to utilize the cheap fulvic acid for applications of Hg0 removal in H 2 S containing natural gas. [ABSTRACT FROM AUTHOR]