Hg Emissions Research Articles

Hg0 chemisorption of magnetic manganese cobalt nano ferrite from simulated flue gas

Mercury (Hg) emissions from the flue gas of coal-fired power plants constituted the primary source of atmospheric mercury pollution, manifesting in three distinct forms: granular mercury, oxidized mercury, and elemental mercury. This pollution posed significant threats to the ecological environment. There was an urgent demand for a more effective and economically viable mercury removal technology. The magnetic Mn0.5Co0.5Fe2O4 nanoparticles were prepared via a rapid combustion process. Their capacities for mercury adsorption and regeneration were scrutinized through a fixed-bed experimental system. The outcomes revealed that Mn0.5Co0.5Fe2O4 nanoparticles, prepared at a calcination temperature of 400 °C with 20 ml of anhydrous ethanol, exhibited the most proficient adsorption of Hg°. Under these specific conditions, the average particle size of the Mn0.5Co0.5Fe2O4 nanoparticles was approximately 26.8 nm. These nanoparticles demonstrated a superior adsorption capacity of 9.48 μg·g−1 for Hg° at an adsorption temperature of 30 °C under a space velocity of 2.4 × 104 h−1. Elevating the permeation temperature to 70 °C resulted in an impressive adsorption capacity for Hg°, reaching 560.59 μg·g−1. The Hg-TPD (Hg-Temperature Programmed Desorption) and XPS (X-ray photoelectron spectroscopy) analyses revealed the involvement of chemisorbed oxygen (Oads), Mn3+, and Fe3+ in the adsorbent, facilitating the oxidation of Hg° and generating HgO on the adsorbent surface. Following six cycles of adsorption and desorption, the adsorption capacity of Mn0.5Co0.5Fe2O4 nanoparticles for Hg° retained 71% of the first adsorption capacity, which indicated that magnetic Mn0.5Co0.5Fe2O4 nanoparticles held great promise as an adsorbent for mercury removal.

Exceptionally low mercury concentrations and fluxes from the 2021 and 2022 eruptions of Fagradalsfjall volcano, Iceland

Mercury (Hg) is naturally released by volcanoes and geothermal systems, but the global flux from these natural sources is highly uncertain due to a lack of direct measurements and uncertainties with upscaling Hg/SO2 mass ratios to estimate Hg fluxes. The 2021 and 2022 eruptions of Fagradalsfjall volcano, southwest Iceland, provided an opportunity to measure Hg concentrations and fluxes from a hotspot/rift system using modern analytical techniques. We measured gaseous Hg and SO2 concentrations in the volcanic plume by near-source drone-based sampling and simultaneous downwind ground-based sampling. Mean Hg/SO2 was an order of magnitude higher at the downwind locations relative to near-source data. This was attributed to the elevated local background Hg at ground level (4.0 ng m−3) likely due to emissions from outgassing lava fields. The background-corrected plume Hg/SO2 mass ratio (5.6 × 10−8) therefore appeared conservative from the near-source to several hundred meters distant, which has important implications for the upscaling of volcanic Hg fluxes based on SO2 measurements. Using this ratio and the total SO2 flux from both eruptions, we estimate the total mass of gaseous Hg released from the 2021 and 2022 Fagradalsfjall eruptions was 46 ± 33 kg, equivalent to a flux of 0.23 ± 0.17 kg d−1. This is the lowest Hg flux estimate in the literature for active open-conduit volcanoes, which range from 0.6 to 12 kg d−1 for other hotspot/rift volcanoes, and 0.5–110 kg d−1 for arc volcanoes. Our results suggest that Icelandic volcanic systems are fed from an especially Hg-poor mantle. Furthermore, we demonstrate that the aerial near-source plume Hg measurement is feasible with a drone-based active sampling configuration that captures all gaseous and particulate Hg species, and recommend this as the preferred method for quantifying volcanic Hg emissions going forward.

Large mercury release from the Greenland Ice Sheet invalidated.

The major input of mercury (Hg) to the Arctic is normally ascribed to long-range transport of anthropogenic Hg emissions. Recently, alarming concentrations of Hg in meltwater from the Greenland Ice Sheet (GrIS) were reported with bedrock as the proposed source. Reported Hg concentrations were 100 to 1000 times higher than in known freshwater systems of Greenland, calling for independent validation of the extraordinary concentrations and conclusions. Here, we present measurements of Hg at 21 glacial outlets in West Greenland showing that extreme Hg concentrations cannot be reproduced. In contrast, we find that meltwater from below the GrIS is very low in Hg, has minor implications for the global Hg budget, and pose only a very limited risk for local communities and the natural environment of Greenland.

Development and optimization of a triple quadrupole ICP-MS-based system for the quantification of pre-concentrated gaseous elementary mercury.

Understanding the redox reactions and transformation rates of mercury (Hg) species in the environment is important for predicting future gaseous elemental Hg (Hg0) levels and assessing the impacts of anthropogenic Hg0 emissions on human health. Stable Hg isotope tracers are a promising tool for estimating Hg0 production rates; however, traditional analytical approaches for quantifying Hg0, such as atomic fluorescence spectroscopy or atomic absorption spectrometry, cannot differentiate between Hg isotopes, and alternative approaches, such as inductively coupled plasma mass spectrometry (ICP-MS) with a typical aqueous sample introductory system, have relatively higher detection limit of Hg. Here, we developed and evaluated a custom-made thermal desorption unit coupled directly to a triple quadrupole ICP-MS (ICP-QQQ) for the quantification of Hg0 pre-concentrated on Au traps. The performance of the system was validated with measurements of a Hg standard gas and of Hg0 generated from aqueous Hg standards. Using our system, we were able to detect ultra-trace amounts of Hg0 and obtain precise Hg isotope measurements with an analytical error of ≤ 3.5%. Calibration curves with superb linearity (r2 > 0.999) were obtained for the Hg concentration range of 0-300pg. The method detection limit was approximately 0.01-0.03pg of Hg. Using the latest ICP-QQQ instrument (Agilent 8900; Agilent Technologies Ltd.) was far superior to using a previous model (Agilent 8800), with the Agilent 8900 showing approximately five times higher sensitivity than the Agilent 8800 as well as the ability to precisely and simultaneously analyze up to five Hg isotopes by time-resolved analysis.

Multimedia fate simulation of mercury in a coastal urban area based on the fugacity/aquivalence method

Due to intensive industrial production and living activities, urban areas are the main anthropogenic mercury (Hg) emission sources. After entering the environment through exhaust gases, wastewater or waste residues, Hg can migrate and transform among different environmental compartments in various species, such as elemental mercury (Hg0), divalent mercury (Hg2+) and methylmercury (MeHg). Studies have yet to report on the multimedia behaviors of Hg in urban areas due to the complexity of the processes involved. In this study, the atmospheric Hg emission in Dalian, a coastal city in Northeast China, was estimated by an anthropogenic emission inventory, and a Level III multimedia model was constructed based on the fugacity/aquivalence method to simulate the fate of Hg in air, water, soil, sediment, vegetation and film. The total annual atmospheric emission was 9.91 t, of which coal combustion and non-coal sources accounted for 70.1 % and 29.9 %, respectively. Atmospheric emission and advection were dominated by Hg0, and aquatic emission and advection were dominated by Hg2+. The migration of air–vegetation, vegetation–soil and soil–air were three important pathways of Hg in urban areas. The model was validated by collecting local soil and vegetation samples and regional air, seawater and sediment monitoring data. The scenario simulation indicated that the local load would decrease to different extents with a 21.0 % reduction in atmospheric Hg emission by implementing the “coal-to-gas” measures. Our developed model can characterize the fate of Hg in coastal urban areas and provide a reference for control strategies.

Poison in the nursery: Mercury contamination in the tadpole-rearing sites of an Amazonian frog

Artisanal and small-scale gold mining (ASGM) has become a major threat for Neotropical forests. This technique for obtaining gold is a substantial driver of small-scale deforestation and the largest contributor of Hg emissions to both the atmosphere and freshwater systems globally. Previous studies have demonstrated the impacts of Hg accumulation on various aquatic ecosystems and organisms. However, its consequences in other, more discrete systems such as phytotelmata (water-holding plant structures), and the organisms therein, have so far gone unnoticed. Here, we show high concentrations of Hg (mean ± SD: 1.43 ± 2.19 ppm) in phytotelmata and other small pools, the aquatic microenvironments used by the Neotropical poison frog Dendrobates tinctorius as tadpole-rearing sites. In 17 % of the cases, we detected Hg concentrations above the severe effect level (SEL = 2 ppm) for freshwater sediments. Hg concentrations varied depending on pool characteristics and tended to increase in proximity to known ASGM sites. We did not find an effect of Hg concentration on the number of D. tinctorius tadpoles in a given pool. Tadpoles were found in pools with concentrations of up to 8.68 ppm, suggesting that D. tinctorius fathers do not avoid pools with high Hg levels for tadpole deposition. While further research is needed to determine the potential effects of Hg on tadpole development, we found an intriguing tendency for tadpoles in later developmental stages to have lower body condition when occurring in pools with higher Hg concentrations. Our findings provide evidence of relevant Hg concentrations in the terrestrial water systems used by phytotelm-breeding anurans, and highlight the need of further field and experimental studies investigating the implications of Hg contamination for tadpole development and behaviour and the overall conservation of Amazonian biodiversity.

Long-Range Atmospheric Mercury Transport from Across East Asia to a Suburban Coastal Area in Southern Vietnam.

Exports of atmospheric mercury (Hg) from continental East Asia, a major Hg emitter in the globe, have been reported by several studies in neighboring countries such as Japan and Korea. Nonetheless, studies concerning this topic in Southeast Asia (SEA) countries are still limited. Accordingly, gaseous elemental mercury (GEM) has been measured from Can Thanh High School (CTHS), a suburban coastal site in southern Vietnam to study its characterization and discover the evidence of Hg trans-boundary transport from regional sources (e.g., East Asia). Data collected in July, August, and October 2022 were used in this study, and the overall GEM concentration was 1.61 ± 0.32 ng m-3. The GEM levels were higher in October than in July and August, potentially due to the discrepancy in air mass transport patterns induced by tropical monsoon and source origins of Hg. MERRA-2, backward trajectories, and CALIPSO images revealed the trans-boundary air pollution from continental East Asia to southern Vietnam, evidenced by significantly elevated (> 30%) atmospheric Hg concentrations as well as other air pollutants when the plume arrived at CTHS. Furthermore, our results also imply that atmospheric Hg exported from East Asia could influence large areas in SEA, suggesting the need for more studies in various SEA countries in the upcoming future. This study illustrated the influence of regional Hg emissions on local atmospheric Hg pollution and provided data to improve knowledge of the Hg biogeochemical cycle in SEA.

Mercury bioaccumulation in bats in Madre de Dios, Peru: implications for Hg bioindicators for tropical ecosystems impacted by artisanal and small-scale gold mining.

Mercury (Hg) endangers human and wildlife health globally, primarily due to its release from artisanal small-scale gold mining (ASGM). During gold extraction, Hg is emitted into the environment and converted to highly toxic methylmercury by microorganisms. In Madre de Dios (MDD), Peru, ASGM dominates the economy and has transformed rainforests into expansive deforested areas punctuated by abandoned mining ponds. The aim of this study was to evaluate the use of bats as bioindicators for mercury pollution intensity in tropical terrestrial ecosystems impacted by ASGM. We collected 290 bat fur samples from three post-ASGM sites and one control site in Madre de Dios. Our results showed a wide Hg distribution in bats (0.001 to 117.71 mg/kg) strongly influenced by feeding habits. Insectivorous and piscivorous bats from ASGM sites presented elevated levels of Hg surpassing the mercury small mammal threshold for small mammals (10 mg/kg). We observed the highest reported fur mercury concentrations for insectivorous Neotropical bats reported to date (Rhynchonycteris naso, 117 mg/kg). Our findings further confirm that Hg emissions from ASGM are entering local food webs and exposing wildlife species at several trophic levels to higher levels of Hg than in areas not impacted by mining. We also found that three bat genera consistently showed increased Hg levels in ASGM sites relative to controls indicating potential usefulness as bioindicators of mercury loading in terrestrial ecosystems impacted by artisanal and small-scale gold mining.

Effects of circulating ash and dolomite on mercury transition during coal step conversion of pyrolysis and combustion

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.

Labile carbon inputs boost microbial contribution to legacy mercury reduction and emissions from industry-polluted soils

Soils is a crucial reservoir influencing mercury (Hg) emissions and soil-air exchange dynamics, partially modulated by microbial reducers aiding Hg reduction. Yet, the extent to which microbial engagements contribute to soil Hg volatilization remains largely unknown. Here, we characterized Hg-reducing bacterial communities in natural and anthropogenically perturbed soil environments and quantified their contribution to soil Hg(0) volatilization. Our results revealed distinct Hg-reducing bacterial compositions alongside elevated mercuric reductase (merA) gene abundance and diversity in soils adjacent to chemical factories compared to less-impacted ecosystems. Notably, solely industry-impacted soils exhibited increased merA gene abundance along Hg gradients, indicating microbial adaption to Hg selective pressure through quantitative changes in Hg reductase and genetic diversity. Microcosm studies demonstrated that glucose inputs boosted microbial involvement and induced 2–8 fold increments in cumulative Hg(0) volatilization in industry-impacted soils. Microbially-mediated Hg reduction contributed to 41.6% of soil Hg(0) volatilization in industry-impacted soils under 25% water-holding capacity and glucose input conditions over a 21-day incubation period. Alcaligenaceae, Moraxellaceae, Nitrosomonadaceae and Shewanellaceae were identified as potential contributors to Hg(0) volatilization in the soil. Collectively, our study provides novel insights into microbially-mediated Hg reduction and soil-air exchange processes, with important implications for risk assessment and management of industrial Hg-contaminated soils.

Over a decade of atmospheric mercury monitoring at Amsterdam Island in the French Southern and Antarctic Lands

The Minamata Convention, a global and legally binding treaty that entered into force in 2017, aims to protect human health and the environment from harmful mercury (Hg) effects by reducing anthropogenic Hg emissions and environmental levels. The Conference of the Parties is to periodically evaluate the Convention’s effectiveness, starting in 2023, using existing monitoring data and observed trends. Monitoring atmospheric Hg levels has been proposed as a key indicator. However, data gaps exist, especially in the Southern Hemisphere. Here, we present over a decade of atmospheric Hg monitoring data at Amsterdam Island (37.80°S, 77.55°E), in the remote southern Indian Ocean. Datasets include gaseous elemental and oxidised Hg species ambient air concentrations from either active/continuous or passive/discrete acquisition methods, and annual total Hg wet deposition fluxes. These datasets are made available to the community to support policy-making and further scientific advancements.

Halogen (Cl, Br, I) regulation Cu-BTC for NH3-SCR: NO and Hg0 removal and mechanism analysis

Emissions of NOx and Hg0 in the atmosphere are primarily derived from coal-fired power plant flue gases. The control of these pollutants has emerged as a focal point of research in recent years. In this study, we synthesized a novel halogen-modified Cu-BTC catalyst designed for the synergistic removal of NO and Hg0. The results showed that: Cu-BTC catalyst maintained its original physicochemical properties even after being modified with different halogens (Cl, Br, I), and C-X (Cl, Br, I) bonds indicated the successful incorporation of halogens into the Cu-BTC. Furthermore, the catalytic performance was investigated through NH3-SCR method. Research indicated that halogens amplified the catalytic reduction of NO and the catalytic oxidation ability of Hg⁰. Furthermore, the effect of post-modification proved to be superior to pre-modification, following the order of Cl＞Br＞I. Under the conditions of 200 °C and 30000 h−1, the Cu-BTC-Cl catalyst exhibited the highest removal efficiency for both NO and Hg⁰, reaching 84.895 % and 76.841 %. While NO had a minor impact, NH₃ enhanced the removal of NO but inhibited the removal of Hg⁰. O2 significantly promoted pollutants removal, and the catalyst also showed strong resistance to both sulfur and water. The modified catalyst exhibited covalent C–Cl species, which effectively captured Hg0. Cu2+ participated in the removal of NO and Hg0, with partial transformation into Cu+.

Impacts of Volcanic Emissions on the Global Biogeochemical Mercury Cycle: Insights From Satellite Observations and Chemical Transport Modeling

AbstractVolcanism is the largest natural source of mercury (Hg) to the biosphere. However, past Hg emission estimates have varied by three orders of magnitude. Here, we present an updated central estimate and interquartile range (232 Mg a−1; IQR: 170–336 Mg a−1) for modern volcanic Hg emissions based on advances in satellite remote sensing of sulfur dioxide (SO2) and an improved method for considering uncertainty in Hg:SO2 emissions ratios. Atmospheric modeling shows the influence of volcanic Hg on surface atmospheric concentrations in the extratropical Northern Hemisphere is 1.8 times higher than in the Southern Hemisphere. Spatiotemporal variability in volcanic Hg emissions may obscure atmospheric trends forced by anthropogenic emissions at some locations. This should be considered when selecting monitoring sites to inform global regulatory actions. Volcanic emission estimates from this work suggest the pre‐anthropogenic global atmospheric Hg reservoir was 580 Mg, 7‐fold lower than in 2015 (4,000 Mg).

A Novel Solution to Avoid Mercury Emissions Produced by Highly Contaminated Demolition Debris in Mining Site

Mercury (Hg) emissions into the air can in some cases be a critical problem for public health and environmental protection. Hence, it is crucial to find cost-effective solutions to tackle this issue. An innovative solution is presented in this study using two case studies, diminishing drastically the emissions through covering high Hg-contaminated debris with industrial subproducts (fly-ashes and blast furnace slags). This solution is compared with other two conventional alternatives: (1) removal of the debris to an authorized landfill and (2) in situ encapsulation. The analysis is carried out by comparing costs, carbon footprint and the Environmental–Social–Governance (ESG) impact. It has been noted that the solution proposed has some advantages with respect to conventional alternatives, from both economic and environmental points of view, presenting lower costs and a lower carbon footprint. The worst solution is to remove the debris for ex situ treatment, while the encapsulation represents a middle solution with advantages and disadvantages. The findings of the study can be a step forward in the usage of industrial subproducts, that are currently placed in waste disposal, to solve the problem of sites contaminated by mercury and eliminate its emissions.

A Quantitative Method to Measure the Kinetics of Elemental Mercury Emissions From Black Shale (Nova Scotia, Canada).

A controlled chamber method using continuous gold trap atomic fluorescence spectroscopy (AFS) (Tekran 2537X) for the analysis of Hg(0) emissions from moderate mass rock samples was developed and tested. A series of black shale and other bedrock samples from Nova Scotia, Canada, were used to test the method and its reproducibility. Hg(0) emissions at 170°C were measured to quantify both free surficial Hg(0) and Hg(0) that had penetrated the rock structure. High volumes of chamber air (45 L) were sampled using 30min collection times to achieve detectable elemental mercury (Hg(0)) emissions. We found higher percentage masses of Hg(0) were released (1.1%-4.1% of total Hg mass present) in black shale samples as compared to granite and basalt samples from the same region (0.0%-0.3% released) over 350h of continuous analysis time. The pseudo first order emission rate constants ranged from 0.015-0.245h-1 (mean 0.063h-1, standard deviation (SD) 0.102) for the black shale samples analyzed and was 0.004h-1 for the granite sample. The 24-h zero-order emission rate constants ranged between 0.41 and 3.54ngh-1 (mean 1.4ngh-1, SD 1.3) for the black shale samples analyzed and were ~ 0.01ngh-1 for the granite and basalt samples. This technique has useful implications for examining rock properties and Hg(0) emission rates.

An interdisciplinary approach evidenced the influence of human activities on honey in Northern Italy

Abstract Background Bees are important environmental indicators, revealing pollution through mortality or residues in honey and other hive products. We compared honey quality in a rural (Western Milan) and an industrial area (Northern Milan-Rho) in Lombardy (Italy). Methods In collaboration with the local Health and Environmental Protection Agencies, we collect and evaluate data regarding organic and inorganic residues in the honey samples from 2011 to 2022. Furthermore, we investigate the possible sources of air emissions through INEMAR database (INventario EMissioni ARia). Results Tetracyclines were detected in one case in the rural area, while Pb concentration was found above legal limits in several samples in the industrial area. INEMAR evidenced combustion in industry and road transport as the main sources of Pb emission in that area. It was also noticed Hg emissions in the rural area, clearly higher than in other territories. Conclusions The fraudulent use of antibiotics to eliminate pathogens, such as Paenibacillus larvae, responsible for American foulbrood, can be at the origin of their presence in the honey. Continuous monitoring of these compounds is critical since their environmental persistence can be very long lasting and a risk for human health. Heavy metals are harmful for human health and can have natural and mostly anthropic origins. The main sources are motor traffic, exhaust gases and fumes, as well as pesticides and synthetic fertilizers. Pb contamination can derive from the location of the apiaries near roads with high vehicular traffic, but in some cases, from the paints used to waterproof hives. The unexpected high Hg emissions better address next monitoring on honey in the rural area where no in-depth Hg analysis has been carried out until now. This interdisciplinarity is a new approach and an essential tool to better understand the influence of anthropic activities and of air pollution on honey quality. Key messages • Comparison of chemical quality (organic and inorganic residues) in honey produced in rural and industrial areas in Lombardy (Northern Italy). • An interdisciplinary approach in honey quality assessment, considering estimated emission loads from anthropic activities in both areas.

High-precision spatio-temporal variations and future perspectives of multiple air pollutant emissions from Chinese biomass-fired industrial boilers

Biomass-fired industrial boilers (BFIBs) are one of the neglected and important anthropogenic sources of air pollutants. A comprehensive boiler-based emission inventory of multiple air pollutants from BFIBs in China in 2020 was first developed based on the activity level database and updated emission factors. Results showed that national emissions of air pollutants from BFIBs in 2020 were estimated to be 11.5 kt of PM, 10.8 kt of PM10, 7.4 kt of PM2.5, 40.5 kt of SO2, 79.8 kt of NOx, 4.2 kt of organic carbon (OC), 1.0 kt of elemental carbon (EC), 31.7 kt of nonmethane volatile organic compounds (NMVOCs), 15.9 kt of NH3, and 116.5 t of five trace metals (Hg, Cr, Cd, Pb, and As), respectively. Air pollutant emissions exhibited significant spatio-temporal heterogeneity. Monthly air pollutant emissions varied by geographical division due to the combined effects of industrial production and winter heating demand. These emissions were mainly concentrated in the eastern coastal region, with Guangdong, Guangxi, Fujian, Jiangsu, and Zhejiang being the five provinces having the highest emissions. In addition, scenario predictions indicate that as the pollution and carbon reduction strategy is implemented, air pollutant emissions from BFIBs in China could become well controlled, with PM, NOx, SO2, and Hg emissions in 2050 projected to be 3.0–8.3 kt, 36.5–75.7 kt, 16.2–32.8 kt, and 0.52–0.87 t, respectively. Our results can provide a highly spatio-temporal resolution inventory of multiple air pollutant emissions from BFIBs for air quality modelling and support the formulation of air pollution control policies for biomass fuel utilization in the context of the pollution and carbon reduction strategy.

Variability in methylmercury exposure across migratory terrestrial bird species: Influencing factors, biomagnification and potential risks

Despite China's considerable mercury (Hg) emissions, monitoring of methylmercury (MeHg) levels in its terrestrial environments remains limited. This study examined the occurrence and accumulation of MeHg in body feathers of 12 migratory terrestrial bird species originating from Siberia and northeastern China. Considerable variations in foraging habits and MeHg levels were observed among these species. Accipiters, including Eurasian and Japanese sparrowhawks (A. gularis and A. nisus) and northern goshawk (A. gentilis), along with insectivorous songbirds including grey-backed thrush (T. hortulorum) and orange-flanked bluetail (T. cyanurus), showed notable levels of MeHg (0.62–1.20 mg/kg). Up to 25 % of the individuals within these species were classified as low-risk based on feather Hg toxicity thresholds, while the remaining species fell into the no-risk category. Despite showing enriched δ15N, MeHg concentrations in short-eared and long-eared owls (A. flammeus and A. otus) were lower than in sparrowhawks. The herbivorous oriental turtle dove (S. orientalis) exhibited significantly lower MeHg levels compared to all other species. There was a significant positive correlation between MeHg concentrations and δ15N across species, highlighting the substantial biomagnification potential of MeHg within the terrestrial food web. Additionally, we found significantly higher MeHg levels in adults than juveniles in both sparrowhawk species. Our results demonstrate the effectiveness of utilizing migratory bird feathers for monitoring terrestrial Hg contamination, and underscore the importance of further assessment.

Tree-rings analysis to reconstruct atmospheric mercury contamination at a historical mining site.

Mercury (Hg) is a global environmental concern due to its toxicity (especially high in methylated form) and the long-range distribution of its gaseous elemental form (GEM). Hg-contaminated areas, such as abandoned mining sites, pose intrinsic difficulties for their management and heavy monitoring costs. In these environments, plant-based solutions may play a key role in the ecosystem quality assessment and support remediation strategies, combining reliability and cost-effectiveness. In this study, we adopted a biomonitoring approach by using tree rings of four different species collected in the proximity of the mining-metallurgical area of Abbadia San Salvatore, central Italy, a major former Hg mining district whose reclamation is currently in progress. Our dendrochemical analysis was aimed at identifying the historical changes of local atmospheric Hg contamination and at singling out, for the first time in the study area, other potentially toxic elements (PTEs) associated with the past mining activity. Collected cores dated back to early as 1940 and provided the temporal patterns of atmospheric Hg emission vs the produced liquid quantities, so reconstructing the historical impact of the mining site on nearby terrestrial ecosystems and resident human population. Current GEM contamination was found about twenty times lower than that of the fully operational mine periods. From a first survey on other PTEs, thallium (Tl) and lead (Pb) appeared to be potentially associated with the mining activity, thus suggesting new working assumptions for further dendrochemical analyses and for the inclusion of Pb in human biomonitoring surveys of the Mt. Amiata area, actually not present in the control list. The results prompt a more thorough assessment by tracking for a longer time span a critical site that is an ideal open-field lab to study the ecophysiology of different tree species in relation to environmental behavior of PTEs for better-assessing wildlife and human exposures.

Development of an online analyser to meet challenging new discharge limits for mercury in flue gas desulphurisation wastewater

Abstract Anthropogenic emissions of mercury to the environment are of great concern due to its toxicity. The burning of coal contributes highly to Hg emissions and, as such, much lower effluent discharge limits for Hg in flue gas desulphurisation (FGD) wastewater have recently been proposed in the USA. Lower detection limits are required to meet the most demanding discharge limit of 10 ng L−1. Therefore, in this work, a new analyser for online monitoring of Hg in FGD wastewater based on syringe injections of chemicals combined with gold amalgamation – atomic fluorescence spectrometry has been developed. The instrument has been validated against international standard method ISO 17852, as well as an interference study with extreme levels of salts majorly present in FGD water. Detection limits of 1.8 ng L−1 as well as accurate performance in an on-site field trial indicate that the methodology is fit to meet the new legislation.