Environmental costs of mercury pollution

Determination of Low Concentrations of Mercury Based on the Electrodeposition Time

Soil plays a crucial role in human health through its impact on food and habitation. However, it often contains toxic heavy metals, with mercury being particularly hazardous when methylated. Currently, high-sensitivity, rapid detection of mercury is achievable only through electrochemical measurements. These measurements require pretreatment of the soil sample and the preparation of a calibration curve tailored to the sample's condition. In this study, we developed a method to determine the environmental standard value of mercury content in soil by significantly reducing the pretreatment process. Our approach involves analyzing current peaks from electrodeposition times using specific electrodes and solvent settings. This method demonstrates low error rates under low concentration conditions and can detect mercury levels as low as 0.5 ppb in soil leachate and reagent dilution series. This research facilitates the determination of low mercury concentrations in solutions containing various soil micro-compounds without the need for calibration curves.

A Novel Rhodamine-Phenolphthalein Architecture for Selective Mercury Ion Detection in Aqueous Media

In this study, the primary objective is to synthesize a novel fluorescent Rh-PP-Rh compound and explore its extensive range of photochemical behaviors. Initially, the synthesis of the novel Rh-PP-Rh was carried out for this purpose. Subsequently, UV-Vis and fluorescence spectroscopy were employed to investigate the interactions between Rh-PP-Rh and a diverse array of ions in aqueous solvent systems. Through fluorescence and UV-Vis studies, it was observed that Rh-PP-Rh demonstrated turn-on sensor properties in the presence of Hg2+ ions. Furthermore, the limits of detection (LOD) and association constant (Ka) values for Rh-PP-Rh/Hg2+ were determined as 334 nM and 9.13×1011 M-2, respectively. Additionally, the reversible studies demonstrated a switchable on/off response upon alternate addition of HgCl2 and [Bu4N]F to Rh-PP-Rh. These findings suggest that the probe Rh-PP-Rh also possesses specific sensor properties for F- ions in the presence of mercury. In addition, the investigation encompassed an assessment of the visual analysis of the color alterations of Rh-PP-Rh both on filter paper and in an EtOH/H2O solution. The findings demonstrated that Rh-PP-Rh can be successfully utilized in solutions containing mercury, as it generates significant color transformations.

Bibliometric analysis on mercury emissions from coal-fired power plants: a systematic review and future prospect

Coal-fired power plants (CFPPs) are one of the most significant sources of mercury (Hg) emissions certified by the Minamata Convention, which has attracted much attention in recent years. In this study, we used the Web of Science and CiteSpace to analyze the knowledge structure of this field from 2000 to 2022 and then reviewed it systematically. The field of Hg emissions from coal-fired power plants has developed steadily. The research hotspots can be divided into three categories: (1) emission characterization research focused on speciation changes and emission calculations; (2) emission control research focused on control technologies; (3) environmental impact research focused on environmental pollution and health risk. In conclusion, using an oxygen-rich atmosphere for combustion and installing high-efficiency air pollution control devices (APCDs) helped to reduce the formation of Hg0. The average Hg removal rates of APCDs and modified adsorbents after ultra-low emission retrofit were distributed in the range of 82-93% and 41-100%, respectively. The risk level of Hg in combustion by-products was highest in desulfurization sludge (RAC > 10%) followed by fly ash (10% < RAC < 30%) and desulfurization gypsum (1% < RAC < 10%). Additionally, we found that the implementation of pollution and carbon reduction policies in China had reduced Hg emissions from CFPPs by 45% from 2007 to 2015, increased the efficiency of Hg removal from APCDs to a maximum of 96%, and reduced global transport and health risk of atmospheric Hg. The results conjunctively achieved by CiteSpace, and the literature review will enhance understanding of CFPP Hg emission research and provide new perspectives for future research.

Mercury speciation in selenium enriched wheat plants hydroponically exposed to mercury pollution

Mercury (Hg) pollution in agricultural soils and its potential pathway to the human food chain can pose a serious health concern. Understanding the pathway of Hg in plants and how the speciation may change upon interaction with other elements used for biofortification can be critical to assess the real implications for the final plant-based product. In that respect, selenium (Se) biofortification of crops grown in Se-poor soil regions is becoming a common practice to overcome Se deficient diets. Therefore, it is important to assess the interplay between these two elements since Se may form complexes with Hg reducing its bioavailability and toxicity. In this work, the speciation of Hg in wheat plants grown hydroponically under the presence of Hg (HgCl2) and biofortified with Se (selenite, selenate, or a 1:1 mixture of both) has been investigated by X-ray absorption spectroscopy at the Hg L3-edge. The main Hg species found in wheat grains was the highly toxic methylmercury. It was found that the Se-biofortification of wheat did not prevent, in general, the Hg translocation to grains. Only the 1:1 mixture treatment seemed to have an effect in reducing the levels of Hg and the presence of methylmercury in grains.

Exploring the origins and cleanup of mercury contamination: a comprehensive review

Mercury is a global pollutant that poses significant risks to human health and the environment. Natural sources of mercury include volcanic eruptions, while anthropogenic sources include industrial processes, artisanal and small-scale gold mining, and fossil fuel combustion. Contamination can arise through various pathways, such as atmospheric deposition, water and soil contamination, bioaccumulation, and biomagnification in food chains. Various remediation strategies, including phytoremediation, bioremediation, chemical oxidation/reduction, and adsorption, have been developed to address mercury pollution, including physical, chemical, and biological approaches. The effectiveness of remediation techniques depends on the nature and extent of contamination and site-specific conditions. This review discusses the challenges associated with mercury pollution and remediation, including the need for effective monitoring and management strategies. Overall, this review offers a comprehensive understanding of mercury contamination and the range of remediation techniques available to mitigate its adverse impacts.

The toxicological assessment of hazardous elements (Pb, Cd and Hg) in low-cost jewelry for adults from Chinese E-commerce platforms: In situ analysis by portable X-ray fluorescence measurement

This article focusses on the environmental implications of low-cost jewelry for adults from Chinese e-commerce platforms ((n = 8) with heavy metal impurities (Pb, Cd and Hg) and their potential impact on human health and the environment. The study highlights the advantages of using portable X-ray fluorescence (pXRF) analysis for rapid, non-destructive, and in situ analysis of heavy metals in jewelry. The results reveal that all products (n = 106) contained heavy metals at varying levels, Hg being the most commonly detected heavy metal. The fact that 71% of the samples exceeded the EU limit for Pb and 51% exceeded the EU limit for Cd is alarming and highlights the need for stricter regulations and monitoring of the jewelry industry to mitigate the risks posed by heavy metals in the environment. The study emphasizes the importance of using pXRF analysis to identify heavy metals in jewelry and address the literature gap in environmental risk assessments of Pb, Cd, and Hg in low-cost jewelry for adults from China. In general, the findings call for urgent action to ensure the safety of consumers and prevent environmental pollution by strengthening regulations and monitoring the jewelry industry.

Understanding the sources of mercury release from coal: A combined experimental and molecular simulation study

Understanding the occurrence modes of mercury in coal is important as its release poses long-term adverse effects on the environment and human health during coal production and utilization. However, the matter still remains a subject of controversy due to differing results from direct and indirect analyses, which suggest various possible modes of occurrence for mercury in coal. Additionally, the experimental measurement of Hg concentration presents challenges, further contributing to the complexity of the issue. A comprehensive investigation of experiments and molecular simulations is conducted herein. Electron probe microanalysis and elemental mapping analysis show that elemental Hg is concentrated in framboidal pyrites while absent in organic matter. To understand the occurrence modes of mercury in inorganic and organic materials at the atomic level, molecular simulations are performed for Hg2+ adsorption and retention in MMT, pyrite, and kerogen slit nanopores. It is found that the inorganic MMT and pyrite surfaces have a greater adsorption capacity than the organic kerogen surface (pyrite > MMT > kerogen). The outer-sphere adsorption is mainly observed with at least one monolayer of water molecules exiting between the ion and mineral surfaces. MMT has the highest retention for Hg2+ transport as the self-diffusion coefficient is the smallest among the three slit pores (MMT < pyrite < kerogen). The high adsorption and retention originate from the strong Hg2+-mineral interaction. These results suggest that mercury in coal is most likely associated with inorganic minerals instead of organic matter.

Sediment mercury concentration of a subtropical mangrove wetland responded to Hong Kong-Shenzhen industrial development since the 1960s

Mercury (Hg) in coastal wetlands is of great concern due to its acute toxicity. We measured the total Hg content (THg) from a ²¹⁰Pb-dated sediment core obtained from the Futian mangrove wetland in Shenzhen Bay, South China to explore the historical variation and possible sources. Our results extend the sediment THg record back to 1960 and reveal three distinct intervals. Interval I (1960-1974) has low and increasing THg values, averaging 83.0 μg/kg; Interval II (1975-1984) witnesses a remarkably increase, peaking in 1980 (261.6 μg/kg) then remaining elevated; Interval III (1985-2014) shows a steady reduction, averaging 118.4 μg/kg. The good correlation among THg, TOC, and Hg/TOC, and the downstream decrease in monitoring sediment THg consistently suggest that the bulk THg are mainly sourced from the Shenzhen River discharge. The different timing in industrial development attributes the elevated THg concentrations during 1975-1984 to Hong Kong industrial sewage pollution.

Development of low-cost copper nanoclusters for highly selective "turn-on" sensing of Hg2+ ions

The development of low-cost earth abundant metal based fluorescent sensors for a rapid and selective nanomolar level detection of Hg²⁺ is essential due to the increasing world-wide concern of its detrimental effect on humans as well as the environment. Herein, we present a perylene tetracarboxylic acid functionalized copper nanoclusters (CuNCs) based "turn-on" fluorescence probe for highly selective detection of toxic Hg²⁺ ions. The fabricated CuNCs exhibited high photostability with emission maximum centered at 532 nm (λ_ex = 480 nm). The fluorescence intensity of CuNCs was remarkably enhanced upon the addition of Hg²⁺ over other competing ions and neutral analytes. Notably, the 'turn-on' fluorescence response exhibits highly sensitive detection limit as low as 15.9 nM (S/N ∼ 3). The time resolved fluorescence spectroscopy suggested the energy transfer between CuNCs and Hg²⁺ ions following either inhibited fluorescence resonance energy transfer (FRET) or surface modification of CuNCs during Hg²⁺ sensing. This study offers the systematic design and development of new fluorescent 'turn-on' nanoprobes for rapid and selective recognition of heavy metal ions.

Mercury-Modulated Immune Responses in Arctic Barnacle Goslings (Branta leucopsis) upon a Viral-Like Immune Challenge

Historical mining activities in Svalbard (79°N/12°E) have caused local mercury (Hg) contamination. To address the potential immunomodulatory effects of environmental Hg on Arctic organisms, we collected newborn barnacle goslings (Branta leucopsis) and herded them in either a control or mining site, differing in Hg levels. An additional group at the mining site was exposed to extra inorganic Hg(II) via supplementary feed. Hepatic total Hg concentrations differed significantly between the control (0.011 ± 0.002 mg/kg dw), mine (0.043 ± 0.011 mg/kg dw), and supplementary feed (0.713 ± 0.137 mg/kg dw) gosling groups (average ± standard deviation). Upon immune challenge with double-stranded RNA (dsRNA) injection, endpoints for immune responses and oxidative stress were measured after 24 h. Our results indicated that Hg exposure modulated the immune responses in Arctic barnacle goslings upon a viral-like immune challenge. Increased exposure to both environmental as well as supplemental Hg reduced the level of natural antibodies, suggesting impaired humoral immunity. Hg exposure upregulated the expression of proinflammatory genes in the spleen, including inducible nitric oxide synthase (iNOS) and interleukin 18 (IL18), suggesting Hg-induced inflammatory effects. Exposure to Hg also oxidized glutathione (GSH) to glutathione disulfide (GSSG); however, goslings were capable of maintaining the redox balance by de novo synthesis of GSH. These adverse effects on the immune responses indicated that even exposure to low, environmentally relevant levels of Hg might affect immune competence at the individual level and might even increase the susceptibility of the population to infections.

Microorganisms isolated from seabirds feathers for mercury bioremediation

Environmental pollution caused by mercury has received increasing attention in recent years. Several studies have warned of the high rates of biomagnification in superior levels of marine food networks affecting seabirds. Although seabird feathers are reported as bioindicators of mercury, the possibility of using the microbiota associated with them for the bioremediation of this metal has not been considered. Despite the potential of the seabird feather microbiota, the cultivable microorganisms from this sample matrix have not been identified. In this study, we isolated and identified the organisms in the feathers from three types of seabirds, two species of penguins (Pygoscelis antartica and Pygoscelis papua) and the brown skua bird (Catharacta lonnbergi) through poisoned media a final concentration of 10 mg / L Hg2+ in the culture medium for the microbial consortia. Yeast isolates belonged to the genus Debaryomyces, Meyerozyma, Papiliotrema, and Rhodotorula, and fungi genera Leiotrametes, Penicillium, Pseudogymnoascus, and Cladosporium were identified. Adult bird feathers with high mercury concentrations can serve as a matrix to isolate microorganisms capable of removing mercury. Keywords: Antarctica, bioremediation, feathers, mercury, microorganisms

Highly Selective MOF-Based Turn-Off Luminescence Detection of Hg2+ Ions in an Aqueous Medium and Its Dual Functional Catalytic Activity toward Aldol Condensation and β-Enamination Reactions

A new organic ligand, 5-(carboxyformamido)isophthalic acid (5-CFIA), was prepared and employed for the synthesis of two compounds [M₃(C₁₀H₄O₇N₁)₂(8H₂O)]·H₂O (M = Cd, Mn). The compounds have three-dimensionally extended structures. Both the compounds were found to be luminescent at room temperature. The luminescence nature was exploited for the detection of Hg²⁺ ions in an aqueous medium with good selectivity. The interactions between Hg²⁺ ions and the compounds quench the luminescence intensity and act as a turn-off sensor. Both the compounds exhibited low limits for the detection of Hg²⁺ ions and in the range mandated by the WHO. The interactions between Hg²⁺ ions and the compound involve the -NH group, which was probed using Raman and IR spectroscopic techniques. These studies provide important pointers toward the mechanism of this turn-off luminescence behavior. The compounds were explored for base-catalyzed aldol condensation and Lewis acid-promoted β-enaminoester formation reactions. The aldol condensation reaction uses the -NH functionality as a base. The studies indicate that the electron-withdrawing group produces products with higher yields. The β-enaminoester reaction uses the Lewis acid centers, and the studies reveal that the electron-withdrawing groups produce lesser yields of the products. The catalytic nature of the reaction and recyclability of the catalysts were also established. The catalytic reactions employ ethanol (aldol condensation) and no solvent (β-enaminoester), which suggests that the reactions are green and environmentally friendly. The Mn compound was observed to be anti-ferromagnetic.

The role of transdisciplinarity for mineral economics and mineral resource management: coping with fallacies related to phosphorus in science and practice

Mineral economics is a genuine multidisciplinary field dealing with economic and policy matters related to the production, distribution, and consumption of mineral commodities. We discuss why the increasing complexity, ambiguity, ambivalence, and social contestation of subjects of mineral economics promote the participation of mineral economists in transdisciplinary processes. These processes relate (a) knowledge from targeted interdisciplinary processes and (b) mitigated discourses among different stakeholders to provide (c) a shared problem definition and to attain shared basic knowledge about problem transformation science and practice. We discuss known examples of misperceptions regarding minerals (phosphorus), such as an imminent scarcity threat, the incorrectly understood causations of the 2007/2008 price peak and present the phosphorus ore-grades increased by 3.2% between 1983 and 2013 fallacies (which is based on the Simpson’s paradox), and only few countries have mineable reserves fallacy. Here, we also illuminate motivations underlying several mineral economics–related misunderstandings. We argue that societally relevant questions require an honest mineral economics knowledge brokership. The example of the Global TraPs project, which targeted sustainable phosphorus management, is presented. Honest brokership to attain a clearinghouse function of science requires trust formation in society. We argue that this calls for increasing the understandability of relationships that are not well-understood, such as “if prices rise, so do stocks.” Wellmer and Becker-Platen’s feedback control cycle may be considered an example of how complex mineral economics can become and how challenging it is to be understandable to scientists from different disciplines and faculties as well as to practitioners whose knowledge may well be used to cope with the complexity of given problems. Thus, the present paper represents a plea for mutual learning between science and practice in order to understand the complex social and economic challenges of mineral resource dynamics.

A Bibliometric Analysis of the Scientific Research on Artisanal and Small-Scale Mining

Mineral resource exploitation is one of the activities that contribute to economic growth and the development of society. Artisanal and small-scale mining (ASM) is one of these activities. Unfortunately, there is no clear consensus to define ASM. However, its importance is relevant in that it represents, in some cases, the only employment alternative for millions of people, although it also significantly impacts the environment. This work aims to investigate the scientific information related to ASM through a bibliometric analysis and, in addition, to define the new lines that are tending to this field. The study comprises three phases of work: (i) data collection, (ii) data processing and software selection, and (iii) data interpretation. The results reflect that the study on ASM developed intensively from 2010 to the present. In general terms, the research addressed focuses on four interrelated lines: (i) social conditioning factors of ASM, (ii) environmental impacts generated by ASM, (iii) mercury contamination and its implication on health and the environment, and (iv) ASM as a livelihood. The work also defines that geotourism in artisanal mining areas is a significant trend of the last decade, explicitly focusing on the conservation and use of the geological and mining heritage and, in addition, the promotion of sustainable development of ASM.

Reconstructing atmospheric Hg levels near the oldest chemical factory in central Europe using a tree ring archive

The Chemical Factory in Marktredwitz (CFM) is known as the oldest chemical factory in Germany (1778-1985), and from the beginning of the 20^th century focused primarily on the production of mercury (Hg) compounds. Due to extensive pollution, together with employee health issues, the CFM was shut in 1985 by a government order and remediation works proceeded from 1986 to 1993. In this study, tree ring archives of European Larch (Larix decidua Mill.) were used to reconstruct changes of air Hg levels near the CFM. Mercury concentrations in larch boles decreased from 80.6 μg kg^-1 at a distance of 0.34 km-3.4 μg kg^-1 at a distance of 16 km. The temporal trend of atmospheric Hg emissions from the CFM reconstructed from the tree ring archives showed two main peaks. The first was in the 1920s, with a maximum tree ring Hg concentration 249.1 ± 43.9 μg kg^-1 coinciding with when the factory had a worldwide monopoly on the production of Hg-based seed dressing fungicide. The second peak in the 1970s, with a maximum tree ring Hg concentration of 116.4 ± 6.3 μg kg^-1, was associated with a peak in the general usage and production of Hg chemicals and goods. We used the tree ring record to reconstruct past atmospheric Hg levels using a simple model of Hg distribution between the larch tree rings and atmosphere. The precision of the tree ring model was checked against the results of air Hg measurements during the CFM remediation 30 years ago. According to the tree ring archives, the highest air Hg concentrations in the 1920s in Marktredwitz were over 70 ng m^-3. Current air Hg levels of 1.18 ng m^-3, assessed in the city of Marktredwitz, indicate the lowest air Hg in the past 150 years, underscoring the effective remediation of the CFM premises 30 years ago.

Health risk assessment of gaseous elemental mercury (GEM) in Mexico City

Emissions of gaseous elemental mercury (GEM or Hg⁰) from different sources in urban areas are important subjects for environmental investigations. In this study, atmospheric Hg measurements were conducted to investigate air pollution in the urban environment by carrying out several mobile surveys in Mexico City. This work presents atmospheric concentrations of GEM in terms of diurnal variation trends and comparisons with criteria for pollutant concentrations such as CO, SO₂, NO₂, PM_2.5, and PM₁₀. The concentration of GEM was measured during the pre-rainy period by using a high-resolution active air sampler, the Lumex RA 915 M mercury analyzer. In comparison with those for other cities worldwide, the GEM concentrations were similar or slightly elevated, and they ranged from 0.20 to 30.23 ng m^-3. However, the GEM concentration was significantly lower than those in contaminated areas, such as fluorescent lamp factory locations and gold mining zones. The GEM concentrations recorded in Mexico City did not exceed the WHO atmospheric limit of 200 ng m^-3. We performed statistical correlation analysis which suggests equivalent sources between Hg and other atmospheric pollutants, mainly NO₂ and SO₂, emitted from urban combustion and industrial plants. The atmospheric Hg emissions are basically controlled by sunlight radiation, as well as having a direct relationship with meteorological parameters. The area of the city studied herein is characterized by high traffic density, cement production, and municipal solid waste (MSW) treatment, which constantly release GEM into the atmosphere. In this study, we included the simulation with the HYSPLIT dispersion model from three potential areas of GEM release. Emissions from industrial corridors and volcanic plumes localized outside the urban area contribute to the pollution of Mexico City and mainly affect the northern area during specific periods and climate conditions. Using the USEPA model, we assessed the human health risk resulting from exposure to inhaled GEM among residents of Mexico City. The results of the health risk assessment indicated no significant noncarcinogenic risk (hazard quotient (HQ) < 1) or consequent adverse effects for children and adults living in the sampling area over the study period. GEM emissions inventory data is necessary to improve our knowledge about the Hg contribution and effect in urban megacity areas with the objective to develop public safe policy and implementing the Minamata Convention.

Multi-functional metal-organic frameworks for detection and removal of water pollutions

Water pollutions have caused serious threats to the aquatic environment and human health, it is of great significance to monitor and control their contents in water. Compared with the traditional...

Isotope investigation of mercury sources in a creek impacted by multiple anthropogenic activities

To investigate mercury (Hg) sources responsible for contamination at Gumu Creek in South Korea, Hg concentration (THg) and Hg isotope ratios were measured in the soil and sediment of Gumu Creek and the samples from a hazardous waste landfill (HWL). The THg ranged between 0.29-327 mg kg^-1 and 9.5-414 mg kg^-1 in the soil and sediment, respectively, reflecting heterogeneous distribution and elevated levels across the entire Gumu Creek. Without the soil with the lowest THg (0.30 ± 0.01 mg kg^-1, n = 3), the δ²⁰²Hg (-0.83 to -0.18‰) and Δ¹⁹⁹Hg (-0.24 to 0.01‰) of the sediment and soil of Gumu Creek were within the ranges of the HWL samples (δ²⁰²Hg; -1.29 to -0.38‰, Δ¹⁹⁹Hg; -0.31 to 0.01‰). The comparison with the literature reporting sediment Hg isotope ratios impacted by various anthropogenic Hg sources revealed a presence of diverse Hg sources at Gumu Creek, including commercial liquid Hg, phenyl-Hg, and fly ash, consistent with the types of waste deposited within the HWL. Using commercial liquid Hg, fly ash, and the soil with the lowest THg as end-members, the ternary mixing model yielded 25-88% and 12-57% contributions from commercial liquid Hg and fly ash to the Gumu Creek sediment, respectively. The results of our study suggest that Hg isotope ratios are an effective tool for screening potential Hg sources at sites where the distribution of Hg is heterogeneous and multiple anthropogenic activities exist.

A population approach for the estimation of methylmercury ToxicoKinetics in red mullets

It is known that, as the vast majority of the anthropogenically emitted mercury can be found in aquatic ecosystems, where several methylating bacteria are present, fish consumption represents the most critical intake source of the most toxic form of mercury, the methylmercury (MeHg). The aim of this work is to predict MeHg levels in the fish muscles which, being the edible portion, are part of the human diet. A physiologically based toxicokinetics model was developed to evaluate the kinetics of MeHg in red mullets. Fishes were described by means of a multi-compartment model including stomach, gut, blood, muscles and an additional compartment virtually encompassing all the remaining organs. Absorption, distribution and excretion were modelled considering different MeHg routes of administration and excretion: intake by ingestion of contaminated food, intake and elimination through inhalation-exhalation and excretion through feces. The model has been firstly validated on Terapon jarbua fish (using the weighted least squares method for parameter estimation) to be subsequently readapted to predict methylmercury concentrations in the muscle of red mullets (using an approximate Bayesian computation approach). This simple multicompartmental model could be considered part, a link in the chain, of a wider more complex project aiming at tracking the fate of MeHg from polluted seawater to the human end consumer. The present study could be useful to surveillance organizations in order to carry out a more comprehensive and informed risk assessment analysis and to take appropriate preventive measures by evaluating possible new MeHg concentration thresholds to minimize public health hazards.

Optimization of copper detection based on polarization-resolved laser-induced breakdown spectroscopy

In order to obtain stable spectral data of copper plasma, a detection platform of polarization-resolved laser-induced breakdown spectroscopy (PRLIBS) was built. The PRLIBS characteristic function of copper was constructed by combining the spectral path of plasma discrete spectrum and contact spectrum. The system can not only measure the original data, but also obtain the polarization information in the spectral data. By analyzing the extraction method of spatial polarized light information, the characteristic model of S-wave intensity information in PRLIBS was derived. The results show that in the decay process of plasma energy, the anisotropy of plasma recombination under local thermal equilibrium makes the number of deflected particles of atoms and electrons different in unit time, which leads to the polarization of radiation. The polarization characteristics of the plasma spectrum decreased with the increase of laser energy density. The S-wave was very active, and the polarization of continuous media was much stronger than that of discrete line emission. The advantages were helpful to obtain more stable characteristic peak signals. As a plasma element identification method, PRLIBS makes up for the deficiency of plasma detection technology, and can provide a scientific basis for the safety and non-destructive detection of heavy metals.

A novel near-infrared optical and redox-active receptor for the multi-model detection of Hg2+ in water and living cells

A key issue for constructing optical and redox-active receptors is how to conjugate a specific sensing kernel with a multi-signal-responsive system to carry out multi-feature analysis. Mercury is considered to be highly toxic to human health and ecological security. In this work, we present a novel near-infrared optical and redox-active receptor that can sense Hg²⁺ at ppb level in aqueous media via multi-model monitors with a low detection limit of 8.4 × 10^-9 M (1.68 ppb). This receptor features a visible detection, 'off-on' fluorescence response, and efficient electrochemistry assessment, as well as pH-insensitivity to Hg²⁺ with high sensitivity. In view of its marked near-infrared emission and fluorescence enhancement, we successfully applied this receptor to visualize Hg²⁺ in live cells. Furthermore, a possible sensing model was established and rationalized with theoretical studies.

Liability allocation in pollution involving multiple responsible parties

World over, the instances where polluters are made to pay for the damages they have caused to the environment are on the rise. If more than one party is found responsible for pollution, our analyses of statutes of different countries, covering more than 57% of the world population and more than 45% of its land area, showed that liability is to be allocated among the involved parties on an equitable basis, often decided by the courts. Analyses of a number of court cases showed that the factors considered for allocation in such cases may be classified into two, technical and non-technical. It was also found that the legal liability of pollution was different from the technical liability in many cases due to the influence of non-technical factors that were very specific to the case. These non-technical factors often do not fall under the investigation purview of an environmental forensic expert who carries out technical investigations to find the responsible parties. Based on the analysis, it is suggested that the liability allocation be a two-stage process; the first stage being technical liability allocation done by the forensic expert and the second stage the final (legal) allocation by the court. It is also suggested that clear guidelines be prepared for technical liability allocation. There was also a felt need to quantify remediability to make the remediation liability allocation easier.

New Pyridine-Bridged Ferrocene-Rhodamine Receptor for the Multifeature Detection of Hg2+ in Water and Living Cells

A challenge in the design of optical and redox-active receptors is how to combine a specific recognition center with an efficient responsive system to facilely achieve multifeature detection in biological and environmental analyses. Herein, a novel ferrocene-rhodamine receptor conjugated with a pyridine bridge was designed and synthesized. This receptor can sensitively sense Hg²⁺ in aqueous media via chromogenic, fluorogenic, and electrochemical multisignal outputs with a low detection limit and fast response time. Moreover, it can be qualified as a fluorescent probe for effectively monitoring Hg²⁺ in living cells. A plausible recognition mode was proposed and rationalized with theoretical calculations.

A reaction-type receptor for the multi-feature detection of Hg2+ in water and living cells

The first optical and redox-active receptor of reaction-type has been developed for efficiently multi-model survey of Hg²⁺.

Organically Functionalized Mesoporous SBA-15 Type Material Bearing Fluorescent Sites for Selective Detection of HgII from Aqueous Medium

Hg(II) contamination in water resources is one of the major health issues in keeping the purity standard of the municipal water supply. Herein, we report a new mesoporous sensor probe material SBA-ABZ-PEA having a 2D-hexagonally ordered mesoporous framework bearing covalently bonded fluorescent sites, and this has been synthesized through a two-step post-synthesis grafting route. A pure silica mesoporous SBA-15 material has been functionalized with (3-chloropropyl)triethoxysilane (ClPTES) to obtain chloro-functionalized SBA-15, which was further reacted with 4-aminobenzaldehyde followed by treatment with 2-(2-pyridyl)-ethylamine resulting in functionalized 2D-hexagonal mesoporous sensor probe SBA-ABZ-PEA. Small angle PXRD, N₂ adsorption/desorption, HRTEM, TGA, and FT-IR studies have been carried out to characterize these materials. Our experimental results suggested successful grafting of the organic moiety on the SBA-15 surface along with preservation of mesoporosity throughout the grafting process. Photoluminescence measurements were carried out in the aqueous suspension of SBA-ABZ-PEA in the presence of different metal cations, like Na^I, Mg^II, Al^III, K^I, Ca^II, Mn^II, Co^II, Cu^II, Zn^II, Cd^II, Pb^II, and Hg^II. This result revealed that, among the various metal-ions, the emission intensity of the mesoporous sensing probe material SBA-ABZ-PEA has been dramatically quenched in the presence of the Hg^II ion. To check the sensitivity of the sensor probe, the fluorescence emission was also studied in the presence of different concentrations of Hg^II ions. A perfect linear plot between the concentrations of Hg^II ions in the aqueous medium with their corresponding fluorescence intensities with a detection limit of 1.2 × 10^-6 M has been observed.

Colorimetric and Fluorescence-Based Detection of Mercuric Ion Using a Benzothiazolinic Spiropyran

A merocyanine dye as a p-toluenesulfonate salt was synthesized. The structure of the dye was characterized using IR, NMR, HR-MS and single crystal X-ray crystallography. The X-ray crystallographic studies revealed the formation of a stacked aggregated structure of the merocyanine dye. The stacking interactions were investigated using the Crystal Explorer program, which estimated the strength of the interactions between different molecular pairs. The merocyanine dye was screened for affinity towards heavy metal ions, which revealed a color change from pink to colorless in the presence of mercuric ions, while other metal ions did not produce a similar change in color. In addition, the fluorescence spectroscopy indicated a change in the fluorescence intensity upon addition of mercuric ions. Both techniques displayed a good limit of detection value towards mercuric ions. In addition, the pixel intensity-based detection technique was also employed for the determination of limit of detection value with the help of a smartphone. The dynamic light scattering (DLS) studies indicated that the optical change occurred in the spectra of the receptor is due to the disaggregation of the receptor induced by mercuric ions. In addition, 1H-NMR studies were also used for investigating the mechanism of interaction between the receptor and the mercuric ions. The density functional theory (DFT) studies were used to investigate the formation of the complex at the molecular level, while time dependent density functional theory (TD-DFT) studies were used to understand the observed absorption spectra through the calculation of electronic excitation parameters, which indicated an increase in the energy difference between ground and the excited state.

Biochemical evidence on the potential role of methyl mercury in hepatic glucose metabolism through inflammatory signaling and free radical pathways

Methylmercury (MeHg) is an extremely important environmental toxicant posing serious health risks to human health and a big source of environmental pollutant. Numerous evidence available showing a link between nervous system toxicity and MeHg exposure. Other forms of mercury are reason of metabolic toxic effects and alteration of DNA in the human body. The sources of exposure could be occupational or other environmental settings. In the present study MeHg was orally gavaged to mice, at doses of 2.5, 5, and 10 mg/kg for 4 weeks. Fasting hyperglycemia, activity of hepatic phoshphoenolpyruvate carboxykinase and glucose 6-phoshphate were reported high as compared to control group. Inflammatory markers like, tumor necrosis factor α, the actual end product of inflammatory mediators' cascade pathway was also raised in comparison to control group. Hyperinsulinemia observed in serum showed clear understanding of mercury induced insulin resistance. Moreover, tissue damage due to increased oxidative stress markers like, hepatic lipid peroxidation, 8-deoxygunosine, reactive oxygen species, and carbonyl groups was significantly higher as compared to control group. MeHg caused a significant reduction in antioxidant markers like ferric reducing antioxidant power and total thiol molecules. The present study highlighted that activity of key enzymes involved in glucose metabolism is changed, owing to MeHg induced toxicity in the liver. Induction of similar toxic effects assumed to be stimulated by the production of high quantity free radicals.

Dually emitting carbon dots as fluorescent probes for ratiometric fluorescent sensing of pH values, mercury(II), chloride and Cr(VI) via different mechanisms

The authors describe the preparation of carbon dots (CDs) that display both blue (~ 410 nm) and yellow (~ 565 nm) emission peaks. The CDs was synthesized by solvothermal treatment of o-phenylenediamine in aqueous ethyl alcohol at pH ~7.0. The CDs are shown to be useful fluorescent probes for pH values in that the ratio of fluorescences at 565 and 410 nm strongly depends on the pH value in the range from 4.5-6.5 and 10.0-13.0, respectively. The blue fluorescence is quenched by 91% by 100 µM solutions of Hg(II) through an electron transfer process, and is restored by 97% an addition of chloride (0.5 mM). The yellow fluorescence, in contrast, is hardly affected. The ratio of fluorescences at 414 and 565 nm drops linearly in the 30 to 60 μM of Hg(II) concentration range, and the limit of detection is 60 nM. Fluorescence is linearly restored in the 70 to 180 μM chloride concentration range, and the LOD is 2.8 nM. Both the blue and the yellow emission are reduced by Cr(VI) (chromate) due to an inner filter effect at pH 3.0. The ratio of fluorescences (410/565 nm) drops linearly in the 20 to 250 μM Cr(VI) concentration range, and the LOD is 260 nM. The method was utilized to analysis of chloride in salt lake brine and of Cr(VI) in spiked tap water. Graphical abstract Schematic presentation of carbon dots with pH-dependent dual emission (at ~ 410 nm and ~ 565 nm). They are shown to be viable fluorescent probes for ratiometric sensing of pH values, mercury(II), chloride and Cr(VI) via different mechanisms.

Weir building: A potential cost-effective method for reducing mercury leaching from abandoned mining tailings

To mitigate mercury (Hg) pollution and reduce Hg downstream transportation, a weir was designed by a river system that had been inflicted by leachate from the slagheap of the Yanwuping Hg mine in Wanshan Hg mining area. A whole year monitoring of Hg species was conducted, and the efficiency of Hg reduction by the weir application was evaluated. The Hg concentrations in the river water were significantly higher in the wet season than in the dry season. Waterflow was confirmed to be the main driving factor for Hg mobilization and transportation, and an episode study revealed that most Hg was released in times of storms. Increased monitoring and preventive maintenance measures need to be taken on barriers in advance of storms. A large proportion of the total Hg (THg) and methylmercury (MeHg) is associated to particles. During the study period, approximately 412 g THg and 4.04 g total MeHg (TMeHg) were released from the YMM slagheap, of which 167 g THg and 1.15 g TMeHg were retained by the weir. Annually, 40.4% THg and 38.4% TMeHg was retained by the weir. Weir construction is considered as a potential cost-effective measure to mitigate Hg in river water and should be promoted and extended in the future after optimization.

Enhancing mercury removal across air pollution control devices for coal-fired power plants by desulfurization wastewater evaporation

Desulfurization wastewater evaporation technology is used to enhance the removal of gaseous mercury (Hg) in conventional air pollution control devices (APCDs) for coal-fired power plants. Studies have affirmed that gaseous Hg is oxidized and removed by selective catalytic reduction (SCR), an electrostatic precipitator (ESP) and wet flue gas desulfurization (WFGD) in a coal-fired thermal experiment platform with WFGD wastewater evaporation. Effects of desulfurization wastewater evaporation position, evaporation temperature and chlorine ion concentration on Hg oxidation were studied as well. The Hg⁰ oxidation efficiency was increased ranging from 30% to 60%, and the gaseous Hg removal efficiency was 62.16% in APCDs when wastewater evaporated before SCR. However, the Hg⁰ oxidation efficiency was 18.99% and the gaseous Hg removal efficiency was 40.19% in APCDs when wastewater evaporated before ESP. The results show that WFGD wastewater evaporation before SCR is beneficial to improve the efficiency of Hg oxidized and removed in APCDs. Because Hg²⁺ can be easily removed in ACPDs and WFGD wastewater in power plants is enriched with chlorine ions, this method realizes WFGD wastewater zero discharge and simultaneously enhances Hg removal in APCDs.

Mobility versus retention of mercury in bare and salt marsh sediments of a recovering coastal lagoon (Ria de Aveiro, Portugal)

During decades, mercury (Hg) was discharged into the Aveiro Lagoon. Twenty-five years after the cessation of discharges, sediment cores were collected at two areas to assess the evolution of the mercury contamination status. Vertical Hg profiles differed considerably between bare and vegetated sediments. Bare sediments contained significantly less Hg (<8 mg kg^-1) than historical data of 1995 (up to 40 mg kg^-1), probably resulting from erosion. Salt marsh sediments were marked by a Hg sub-surface enrichment, reaching 44 mg kg^-1 in the site closer to the industrial discharge point. High Hg concentrations in 2007, 2011 and 2016 were found at similar sediment layers. These results emphasise the role of halophyte plants in the cycling and retention of Hg in sediments. The persistency of high Hg in the upper marsh layers highlights the complexity in the recovery of historically contaminated marshes and the vulnerability to modifications in hydrology associated with climate changes.

Friends or foes? Monetized Life Cycle Assessment and Cost-Benefit Analysis of the site remediation of a former gas plant

Site contamination is a global concern because of the potential risks for human health and ecosystem quality. Every contaminated site has its own specific characteristics and the increased availability and efficiency of remediation techniques makes the choice of remediation alternative increasingly complicated. In this paper an attributional Life Cycle Assessment (LCA) of the secondary environmental impacts of a site remediation is performed and its results are monetized using two different monetization techniques, namely Stepwise 2006 and Ecovalue 08. Secondly, we perform a social Cost-Benefit Analysis (CBA) on the same case study using the same data sources. The case study used in this paper entails the soil and groundwater remediation of a tar, poly-aromatic hydrocarbons (PAH) and cyanide contamination of a school ground by a former gas plant. The remediation alternative chosen in this case study is excavation with off-site thermal treatment of the contaminated soil. The outcome of the social CBA, stating that the remediation project is socially beneficial in the long term, is critically compared to the outcome of the different LCA monetization methods. This comparison indicates that monetized LCA is a good complement to social CBA when it comes to the assessment of secondary environmental impacts. Combining the two methods provides decision makers with a more extensive and detailed assessment of the soil remediation project.

A thiourea-appended rhodamine chemodosimeter for mercury(II) and its bioimaging application

A rhodamine-thiourea conjugate RTP with an o-phenylenediamine linker was developed as a fluorogenic chemodosimeter for Hg²⁺ detection. In the presence of Hg²⁺, a colorless solution of RTP turned pink with a maximum absorption band at 555nm and with a 62-fold fluorescence enhancement at 578nm (Φ=0.34). RTP is highly selective to Hg²⁺ among other metal ions with a detection limit of 1.6nM (0.3ppb). A similar rhodamine analog with a flexible ethylenediamine spacer was less selective and less sensitive than RTP. Hg²⁺ induced cyclic guanylation to yield a benzimidazole moiety and a subsequent ring-opening of the spirolactam unit resulted in chromogenic and fluorogenic changes. The membrane-permeable RTP probe was successfully demonstrated in monitoring of Hg²⁺ in cultured HeLa cells.

Study on non-isothermal kinetics of the thermal desorption of mercury from spent mercuric chloride catalyst

Kinetics of the thermal desorption of mercury from spent mercury chloride catalysts were investigated using non-isothermal thermal analysis technique. Complex mercury species absorbed on waste catalysts were revealed by sequential extraction procedure. A scheme of six reactions was applied to elucidate mercury desorption kinetics. Activation energy estimated by model-free isoconversional methods is a slightly increasing function of conversion, implying a variation in the mechanism controlling mercury desorption. Average value of apparent activation energy (116.32kJ/mol) calculated by isoconversional Starink method was used to determine reaction mechanism using model-fitting and z(α) master method. One dimensional diffusion appears to govern mercury desorption process in the conversion range of 10%-40%, and then the reaction kinetic is controlled by two and three dimensional diffusion at greater conversion.

The role of melting alpine glaciers in mercury export and transport: An intensive sampling campaign in the Qugaqie Basin, inland Tibetan Plateau

Glaciers, particularly alpine glaciers, have been receding globally at an accelerated rate in recent decades. The glacial melt-induced release of pollutants (e.g., mercury) and its potential impact on the atmosphere and glacier-fed ecosystems has drawn increasing concerns. During 15th-20th August, 2011, an intensive sampling campaign was conducted in Qugaqie Basin (QB), a typical high mountain glacierized catchment in the inland Tibetan Plateau, to investigate the export and transport of mercury from glacier to runoff. The total mercury (THg) level in Zhadang (ZD) glacier ranged from <1 to 20.8 ng L^-1, and was slightly higher than levels measured in glacier melt water and the glacier-fed river. Particulate Hg (PHg) was the predominant form of Hg in all sampled environmental matrices. Mercury concentration in Qugaqie River (QR) was characterized by a clear diurnal variation which is linked to glacier melt. The estimated annual Hg exports by ZD glacier, the upper river basin and the entire QB were 8.76, 7.3 and 157.85 g, respectively, with respective yields of 4.61, 0.99 and 2.74 μg m^-2 yr^-1. Unique landforms and significant gradients from the glacier terminus to QB estuary might promote weathering and erosion, thereby controlling the transport of total suspended particulates (TSP) and PHg. In comparison with other glacier-fed rivers, QB has a small Hg export yet remarkably high Hg yield, underlining the significant impact of melting alpine glaciers on regional Hg biogeochemical cycles. Such impacts are expected to be enhanced in high altitude regions under the changing climate.