Measurements of gaseous elemental mercury (GEM), particulate mercury (Hg
p), and reactive gaseous mercury (RGM) were concurrently recorded at an urban site in Detroit and a rural site in Dexter, both ...in Michigan for the calendar year 2004. Their average concentrations (±standard deviation) for the urban area were 2.5 ± 1.4 ng m
−3, 18.1 ± 61.0 pg m
−3, and 15.5 ± 54.9 pg m
−3, respectively, while their rural counterparts were 1.6 ± 0.6 ng m
−3, 6.1 ± 5.5 pg m
−3, and 3.8 ± 6.6 pg m
−3, respectively. The medians of urban-to-rural ratios of Hg concentrations indicate approximately 1-fold, 2-fold, and 3-fold gradients between Detroit and Dexter for GEM, Hg
p, and RGM, respectively. The urban–rural differences in Hg also varied considerably on different temporal scales and with wind flow patterns, which was most evident in RGM. Our results show that while Hg at both sites was impacted by regional sources, meteorological conditions, and photochemical transformations, the extent of variations in the observed urban-to-rural gradients, particularly in RGM, cannot be fully accounted for by these processes. Both analyses of the annual data and case studies indicate that the more variable and episodic nature of Hg, particularly RGM, seen in Detroit compared with Dexter, was the result of direct impact from local anthropogenic sources.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Although there have been numerous studies on metal sulphide precipitation, the research field as a whole is not well integrated. This paper reviews the disparate areas of study into metal sulphide ...precipitation in an attempt to summarise the current work, as well as to suggest potential for future consolidation in the field. The review encompasses (1) fundamental studies into metal sulphide precipitation, which usually focus on mechanisms and are carried out at very low (micromolar) concentrations; (2) applied studies focussing on metal removal and reaction kinetics (mostly via the aqueous phase); (3) studies that focus on the solid phase and address the crystallization kinetics of the formed particles; (4) studies into precipitation of metal sulphide nanocrystals and lastly, (5) applications of metal sulphide precipitation to effluent treatment processes such as Acid Mine Drainage (AMD) treatment as well as industrial hydrometallurgical processes.
The review found that, besides lack of integration between the fundamental and applied areas of study, the applied studies have often used flawed methods to evaluate the efficiency of the metal sulphide precipitation process. Applying classical crystallization theory has also not been entirely successful because of the sparingly soluble nature of the systems. The studies that investigate nanocrystal formation tend to focus mostly on recipes and characterization of the formed particles. The industrial and effluent treatment studies form another area of research that stands relatively isolated from its more scientific counterparts.
One of the key insights obtained from the summary of these disparate areas of work is that the level of scientific understanding in each of the fields is vastly different. The fundamental studies into mechanistic aspects of metal sulphide precipitation are far advanced of the other areas. However, they are restricted to very low concentrations, which are of limited value in most process-based hydrometallurgical applications. Most of the applied studies are still at a relatively empirical level, with the findings being highly system-dependent. Truly generic findings are still to be realised in these areas.
Developing robust measurement techniques to be able to collect consistent data and thus model the simultaneous nucleation, growth, aggregation and attrition of the nano to micro scale particles is one of the challenges in the field. Understanding and characterising the complex aqueous chemistry, taking into account multiple sulphide and metal species interactions, is another.
It is proposed that, by integrating the different priorities of the various study areas (chemistry, reaction mechanisms, crystallization mechanisms, particle characterization and industrial applications) the research field as a whole would benefit.
►The major highlight of this research paper is that it is an original review paper of work in the field of metal sulphide precipitation. Although there have been numerous studies on metal sulphide precipitation, the research field as a whole is not well integrated. The paper reviews the disparate areas of study into metal sulphide precipitation in an attempt to summarise the current work, as well as to suggest potential for future consolidation in the field. ►The review found that, besides lack of integration between the fundamental and applied areas of study, the applied studies have often used flawed methods to evaluate the efficiency of the metal sulphide precipitation process. Applying classical crystallization theory has also not been entirely successful because of the sparingly soluble nature of the systems. The studies that investigate nanocrystal formation tend to focus mostly on recipes and characterization of the formed particles. The industrial and effluent treatment studies form another area of research that stands relatively isolated from its more scientific counterparts. ►One of the key insights obtained from the summary of these disparate areas of work is that the level of scientific understanding in each of the fields is vastly different. The fundamental studies into mechanistic aspects of metal sulphide precipitation are far advanced of the other areas. However, they are restricted to very low concentrations, which are of limited value in most process-based hydrometallurgical applications. Most of the applied studies are still at a relatively empirical level, with the findings being highly system-dependent. Truly generic findings are still to be realised in these areas. ►Developing robust measurement techniques to be able to collect consistent data and thus model the simultaneous nucleation, growth, aggregation and attrition of the nano to micro scale particles is one of the challenges in the field. Understanding and characterising the complex aqueous chemistry, taking into account multiple sulphide and metal species interactions, is another. ►It is proposed that, by integrating the different priorities of the various study areas (chemistry, reaction mechanisms, crystallization mechanisms, particle characterization and industrial applications) the research field as a whole would benefit.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•The rationally designed receptor forms Hg(II) complex easily.•The Hg(II) complex senses I− via turn-on fluorescent in aqueous solution.•The mechanism of sensing involves displacement ...of metal ion from the complex.•This complex exhibited many advantages than similar in-situ generated Hg(II) complexes.
A simple Schiff base ligand (L) bearing 3,5-dibromo-2-hyrdoxybenzaldehyde fluorophore moiety has rationally been designed, synthesized and characterized. The Hg(II) complex of L has been synthesized by simply stirring a mixture of L and HgCl2 in ethanol at RT and the resultant non-fluorescent complex HgL is found to detect iodide ion selectively, with a turn-on fluorescence in H2O:DMSO (1:1 v/v) medium. The detection of iodide is performed via the metal ion displacement mechanism with a 1:2 (Probe:Iodide) stoichiometry and binding constant of 1.51x104 M−1. The results indicated that novel HgL complex showed rapid response towards iodide ion with a limit of detection (LOD) as low as 60 nM. Moreover, the sensing mechanism of iodide by the complex is theoretically supported by density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations. In addition, estimation of iodide in real water samples, table salt and urine sample demonstrate the practical value of the probe.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Over the past few decades, the design of an intelligent Intrusion Detection System (IDS) remains an open challenge to the research community. Continuous efforts by the researchers have resulted in ...the development of several learning models based on Artificial Neural Network (ANN) to improve the performance of the IDSs. However, there exists a tradeoff with respect to the stability of ANN architecture and the detection rate for less frequent attacks. This paper presents a novel approach based on Helly property of Hypergraph and Arithmetic Residue-based Probabilistic Neural Network (HG AR-PNN) to address the classification problem in IDS. The Helly property of Hypergraph was exploited for the identification of the optimal feature subset and the arithmetic residue of the optimal feature subset was used to train the PNN. The performance of HG AR-PNN was evaluated using KDD CUP 1999 intrusion dataset. Experimental results prove the dominance of HG AR-PNN classifier over the existing classifiers with respect to the stability and improved detection rate for less frequent attacks.
•A Hypergraph and Arithmetic Residue based PNN (HG AR-PNN) is proposed for IDS.•HG AR-PNN uses Helly-based feature selection technique.•HG AR-PNN was evaluated with respect to precision, recall, accuracy and stability.•Arithmetic residue of the input feature vectors improves the stability of HG AR-PNN.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Mercury (Hg) concentration in fish of the Gulf of the Mexico (GoM) is a major concern due to the importance of the GoM for U.S. fisheries. The Deepwater Horizon (DWH) oil spill in April 2010 in the ...northern GoM resulted in large amounts of oil and dispersant released to the water column, which potentially modified Hg bioaccumulation patterns in affected areas. We measured Hg species (methylmercury (MMHg) and inorganic Hg (IHg)) concentrations, and light (C, N and S) and Hg stable isotopes in muscle and liver tissues from tilefish (Lopholatilus chamaleonticeps) sampled in 2012 and 2013 along the shelf break of the northeastern GoM. Fish located close to the mouth of the Mississippi River (MR) and northwest of the DWH well-head (47 km) showed significantly lower Hg levels in muscle and liver than fish located further northeast of the DWH (>109 km), where 98% of tilefish had Hg levels in the muscle above US consumption advisory thresholds (50% for tilefish close to the DWH). Differences in light and Hg stable isotopes signatures were observed between these two areas, showing higher δ15N, and lower δ202Hg, Δ199Hg and δ34S in fish close to the DWH/MR. This suggests that suspended particles from the MR reduces Hg bioavailability at the base of the GoM food chains. This phenomenon can be locally enhanced by the DWH that resulted in increased particles in the water column as evidenced by the marine snow layer in the sediments. On the other hand, freshly deposited Hg associated with organic matter in more oligotrophic marine waters enhanced Hg bioaccumulation in local food webs. Comparing Hg isotopic composition in liver and muscle of fish indicates specific metabolic response in fish having accumulated high levels of MMHg.
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•Hg in fish of the Gulf of the Mexico is a concern due to commercial fisheries.•We hypothesized that the Deepwater Horizon oil spill affected Hg availability.•About 90% of tilefish surpassed Hg thresholds of U.S. regulations for food.•Mississippi River inputs combined with oil caused reduced Hg bioavailability.•Hg concentrations and isotopes in fish organs reflect in vivo processes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the past few decades, mercury (Hg) discharged into the coastal bays of China has significantly increased; however, long-term trends regarding the pollution status and sources of Hg in these bays ...have yet to be clear. Focusing on this issue, surface sediments and core sediments were collected in the Jiaozhou Bay (JZB), a typical bay highly affected by human activities in China, to analyze the concentrations and stable isotopic composition of Hg. Total mercury (THg) concentrations in surface sediment varied from 7 to 163 ng/g, with higher levels located in the eastern JZB, possibly attributed to intensive industrial and population density. THg in sediment cores 14 and 20 displayed fluctuating increasing trends from 1936 to 2019, reflecting the deterioration of Hg pollution. In contrast, THg in sediment core 28 near the river mouth exhibited a declining trend, possibly due to the river dam construction. Using a stable isotope mixing model, contributions of various sources (atmospheric, riverine, and industrial emissions) to Hg in the JZB were estimated. The results showed that industrial emissions were the main source (over 50%) of mercury in the JZB in 2019. Sediment cores recorded an increase in industrial Hg due to early industrialization and Reform and Opening-up before 2000. In addition, sediment core 20 demonstrated a rise in the percentage of riverine Hg due to land reclamation at the bay's mouth during 2000–2007.
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•Higher Hg levels were observed in the eastern part of the Jiaozhou Bay (JZB).•Bay system is more susceptible to industrial Hg emission compared to marginal seas.•Sediment cores recorded the increase in Hg originated from industry with time.•Reclamation activities increased the riverine input of Hg in the bay mouth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mercury contamination is one of the most serious environmental problems. It can cause serious effects on the human health, such as case damage in the brain, nervous system, immune system, and kidney ...failure. Therefore, development of an accurate, sensitive, and simple operational detection method for mercury is very necessary. Herein, we report a new strategy for mercury ion detection based on commonly used PCR technique. High selectivity and sensitivity were achieved by the formation of the thymine‐Hg‐thymine (T‐Hg‐T) unnatural base pair at the 3’‐end of PCR primers. The detection results of PCR amplification in presence of mercury ion could be reported either by using agarose gel analysis or through real‐time fluorometric dye tracing for different detection purposes. To our knowledge, this study represents the first application of PCR based technique to the detection of metal ions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Mercury (Hg) is one of the major airborne emissions from coal combustion sources. Mercury emissions can be a serious pollution issue that is harmful to human health. Activated carbon (AC) is one of ...the most promising sorbents for Hg adsorption to date. Due to its high cost of chemical preparation, an affordable alternative activated carbon with a high Hg-capturing capacity would be beneficial to environmental security. This study focused on investigating the use of anthracite coal-based activated carbon (ACAC) prepared by a chemical activation method to remove elemental Hg from simulated flue gas. An activation process was developed by evaluating different carbonization temperatures, reagent/coal mass ratios and treating environments. The sample with the highest surface area was selected for synthesizing a bromide-impregnated ACAC. The ACAC sample prepared with KOH at a carbonization temperature of 800 °C, KOH/anthracite mass ratio of 1:1, and activated in an N2 environment yielded a surface area of 527.43 m2/g. Mercury adsorption experiments using synthesized ACAC in simulated flue gas were conducted at two different temperatures, 20° and 100 °C, with exposure times of 2.5 and 1 h, respectively. The kinetic adsorption capacity was found to increase with decreasing temperature. Specifically, at the Hg-laden gas temperature of 20 °C, with 2.5 h exposure time, the adsorbent can achieve the maximum adsorption capacity of 476.51μ g/g. The bromide-impregnated ACAC was also investigated under two different temperatures of 20 °C and 100 °C and exposure of 5 h. The adsorption capacity of the bromide-impregnated ACAC was found to be higher at elevated temperatures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In Suriname, mercury (Hg) use has recently increased because of gold mining, which has put fish-reliant communities (e.g., Indigenous and Tribal) at risk of enhanced Hg exposure through the riverine ...fish these communities consume. To quantify how the magnitude of these risks change according to location and time, we measured total mercury (HgT) in fish at sites downstream and upstream of an artisanal and small-scale gold mining (ASGM) operation in 2004–2005 and in 2017–2018. We tested whether fish HgT burdens over dynamic ranges were increased. Surprisingly, our findings did not support broadly increased fish Hg burden over time or that proximity to ASGM was diagnostic to fish HgT-burden. Subsequently, we elected to test the HgT stable isotope ratios on a set of freshly collected 2020 fish to determine whether differences in Hg source and delivery pathways might cofound results. We found that remote unmined sites were more susceptible to gaseous elemental Hg deposition pathways, leading to enhanced risk of contamination, whereas ASGM proximate sites were not. These results highlight that elemental mercury releases from ASGM practices may have significant impact on fish-reliant communities that are far removed from ASGM point source contamination.
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•Fish mercury burdens did not noticeably increase over a 20-year delay span.•Fish mercury burdens were inconsistent with typical size-burden relationships.•Fish were increased in mercury relative to global trends even in remote areas.•Proximity to mercury-use gold mining was a poor predictor for fish mercury.•Remote intact ecosystems were more mercury sensitive than disturbed ecosystems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A hierarchically porous carbon functionalized with Fe-Mn oxide was fabricated for superior removal of Hg(II) from water.•The composite exhibits high adsorption efficiency of 96.8% and fast ...adsorption rate for the removal of Hg(II).•The high efficiency is contributed by the synergy between physical and chemical adsorption.•The adsorption kinetics agrees with the pseudo-second order model, and isotherms are consistent with the Freundlich model.
The removal of heavy metal ions from industrial wastewater by adsorption has been central to the environment for decades, where common adsorbent materials are often limited by poor efficiency, complex fabrication and long processing time. Porous carbon derived from biospecies holds promise to address the limitations. In this study we converted bagasse into a carbon composite having hierarchically porous structure; the composite’s dispersion phases – iron oxide and manganese oxide – were synthesized by a simple one-step liquid-phase reaction method. Featuring large specific surface area of 350.8 m2 g−1, the composite demonstrated exceptional Hg (II) removal efficiency of 96.8%, adsorption rate of up to 96.8% within 150 min and adsorption capacity of 9.8 mg g−1. In comparison with other removal materials, our work is outstanding in terms of both removal efficiency and synthesis simplicity. The high efficiency is attributed to the synergy between physical adsorption referring to hierarchically porous structure and chemical adsorption relating to functional complexation processes. It provides a new avenue for the development of high-performance adsorbent materials for heavy metal removal from aqueous media.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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