High Mercury Concentrations Research Articles

Total mercury, chromium, nickel and other trace chemical element contents in soils at an old cinnabar mine site (Merník, Slovakia): anthropogenic versus natural sources of soil contamination.

The aims of this study were to investigate the occurrence and distribution of total mercury (Hg) and other trace elements of environmental concern, such as arsenic (As), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn) and vanadium (V), in soils from the abandoned Merník cinnabar mine in eastern Slovakia. For this purpose, thirty soil samples from two depth intervals within the mine area (n = 60 soil samples) and additional sixteen soil samples from adjacent areas (n = 25 soil samples) were collected. Total Hg was measured by atomic absorption spectrometry, while As and other metals were analyzed using inductively coupled plasma atomic emission spectrometry. High mercury concentrations (> 100mg/kg with a maximum of 951mg/kg) were observed only in surface soils close to mine waste heaps and adits. Otherwise, Hg concentrations in the majority of surface soils were lower (0.14-19.7mg/kg), however, higher than Hg in soils collected from sites outside the mine area (0.19-6.92mg/kg) and even considerably higher than Hg in soils at sites not influenced by the Merník mine. Elevated Cr and Ni concentrations in soils regardless of their sampling sites (mean of 276mg/kg and median of 132mg/kg for Cr and 168mg/kg and 81mg/kg for Ni, respectively) were attributed to the lithology of the area; the soils are underlain by the sediments of the Central Carpathian Palaeogene, containing a detritus of ultrabasic rocks. As our geochemical data are compositional in nature, they were further treated by compositional data analysis (CoDA). Robust principal component analysis (RPCA) applied on centred (clr) log-ratio-transformed data and correlation analysis of compositional parts based on symmetric balances distinguished very well different sources of origin for the chemical elements. The following three element associations were identified: Hg association with the main source in mining/roasting, Cr-Ni association derived from bedrock and As-Cu-Mn-Pb-Zn-V association (natural background and minor sulphides/sulfosalts in mineralized rocks). The values of geoaccumulation index and enrichment factor suggested that concentrations of Hg in the soils were influenced by human industrial activities.

Outstanding Performance of Recyclable Amorphous MoS3 Supported on TiO2 for Capturing High Concentrations of Gaseous Elemental Mercury: Mechanism, Kinetics, and Application.

Hg0 capture by sorbents was a promising technology to control Hg0 emission from coal-fired power plants and smelters. However, the design of a high performance sorbent and the predicting of the extent of Hg0 adsorption were both extremely limited due to the lack of adsorption kinetics and structure-activity relationship. In this work, the adsorption kinetics of gaseous Hg0 onto MoS3/TiO2 was investigated and kinetic parameters were obtained by fitting breakthrough curves. According to the kinetic parameters, the removal efficiency, the adsorption rate and the capacity for Hg0 capture were accurately predicted. Meanwhile, the structure-activity relationship of metal sulfides for gaseous Hg0 adsorption was built. The chemical adsorption rate of gaseous Hg0 was found to mainly depend on the amount of surface adsorption sites available for the physical adsorption of Hg0, the amount of surface S22- available for Hg0 oxidation and gaseous Hg0 concentration. As MoS3/TiO2 showed a superior performance for capturing high concentrations of Hg0 due to the large number of surface adsorption sites for the physical adsorption of gaseous Hg0, it has promising applications in recovering Hg0 from smelting flue gas.

One Step Interface Activation of ZnS Using Cupric Ions for Mercury Recovery from Nonferrous Smelting Flue Gas.

The flue gases with high concentration of mercury are often encountered in the nonferrous smelting industries and the treatment of mercury-containing wastes. To recover mercury from such flue gases, sorbents with enough large adsorption capacity are required to capture and enrich mercury. ZnS is a cheap and readily prepared material, and even can be obtained from its natural ores. In this work, a simple controllable oxidation method-soaking in cupric solution-was developed to improve the interfacial activity of ZnS and its natural ores for Hg0 adsorption. The gaseous Hg0 adsorption capacity of ZnS was enhanced from 0.3 to 3.6 mg·g-1 after such treatment. Further analysis indicated that a new interface rich in S1- ions was formed and provided sufficient active sites for the chemical adsorption of Hg0. In addition, the cyclic Hg0 adsorption and recovery experiments demonstrated that the adsorption performance of spent activated-ZnS was recovered after reactivating sorbents with Cu2+, indicating the recovery of activated interface. Meanwhile, the high concentration of adsorbed mercury at the surface can be collected using a thermal treatment method. Utilization of raw materials from a zinc production process provides a promising and cost-effective method for removing and recovering mercury from nonferrous smelting flue gas.

Risk of Mercury Exposure from Fish Consumption at Artisanal Small-Scale Gold Mining Areas in West Nusa Tenggara, Indonesia.

Background.The primary environmental risk associated with artisanal small-scale gold mining (ASGM) activities in Sekotong and Taliwang is waste discharged directly into the environment. This waste contains variable concentrations of heavy metals and a high level of mercury. When these elements are released into the environment, plants and animals can be contaminated. If mercury is methylated to methylmercury, levels can increase in concentration at each level of the food chain (biomagnify). Fish are a primary risk vector for methylmercury poisoning in humans, and represent a significant source of protein for the Sekotong and Taliwang communities.Objectives.The present study aimed to identify the concentration of mercury in fish from ASGM sites in Sekotong and Taliwang.Methods.Descriptive research was used to describe the mercury concentrations of fish in the present study. The fish species collected for the samples represented commercially available fish most commonly consumed by the community on a daily basis.Results.In Sekotong's ASGM area, the mercury concentration in Pilsbryoconcha exilis tissue was 596 ppb, 721 ppb for Sephia officinalis and 50% of the Euthynnus affinis samples had a high level of mercury, above the World Health Organization (WHO) maximum permissable limit for the sale of fish for human consumption of 0.5 ppb.Conclusions.Some fish species from the studied ASGM sites had high mercury concentrations above the maximum permissible mercury concentration in edible fish tissue. The risks associated with mercury exposure from fish consumption threaten community health.Ethics Approval.All experiments were performed in accordance with relevant local guidelines and regulations.Competing Interests.The authors declare no competing financial interests.

Evaluation of mercury levels in hair of children resident in artisanal gold mining area in the city of Chapada de Natividade - Tocantins

ABSTRACT The objective of the work is to evaluate the mercury exposure of children living in an artisanal gold mining area and in a control area, without mining. A cross-sectional study was conducted with children living in the municipalities of Chapada de Natividade and Porto Nacional, in the State of Tocantins, where hair samples were collected for laboratorial analysis of mercury concentrations, comparing between municipalities, gender, monthly fish consumption, profession of parents and the presence of amalgam in dental restorations. The hair samples were analyzed by the methods of neutron activation analysis and also by means of the DMA (Direct Mercury Analyzer) equipment, in the last case being a partnership with CETESB. There was no evidence of mercury-related diseases in the studied children. The mean concentration of mercury in children in Chapada de Natividade was significantly higher than in Porto Nacional. Children exposed to artisanal gold mining areas have higher concentrations of mercury than children living in non- artisanal gold mining areas. There was no significant relationship between mercury concentrations and gender, monthly fish consumption, parental profession and amalgam presence in dental restorations. The results suggest that the children living in an area exposed to mining experience greater environmental exposure to mercury, regardless of their eating habits.

The exposure and toxic effects of mercury in gold mining activities

Background: Mercury is used by artisanal — small-scale (ASM) gold miners throughout the World. In 2014, the Sudanese government produced over 60 tons of gold, which make Sudan ranked Africa's third-largest gold miner. Also, Sudan is ranked the 15th global producer. In 2015, over 1 million miners participated in gold mining and extraction. Objective: This study aimed to determine mercury health risk in Sudanese traditional gold mining activities area.
 Method: This is an analytical cross-sectional observational stud. The studied population was from ALTWAHEN near ABUHAMED. Urine analysis was supported by epidemiological questionnaires designed by (EPI INFO software) following WHO guidelines. Eighty-six respondents completed the questionnaire. The mercury level was determined in 58 urine sample by Petroleum Laboratories Using Direct Mercury Analyzer DMA- 80 instrument. The epidemiological data were analyzed by (EPI INFO).
 Result: 98% exceed concentration of 100 ug/L which contaminated concentration for occasionally exposed, mean urinary mercury concentration 2785 ug/L, the highest mercury concentration worldwide reported by our study 10250 ug/L, Symptoms in 58 patient showed as Problem finding correct word 46.6%, memory problem 27.6%, problem with thinking clearly 29.3%, nervousness 31%, sadness 46.5%, sexual problem 36.2%, headache 51.7%, excessive salivation 43%, drowsy 48.3%.
 Conclusion: In this study, the highest urinary mercury concentration was reported (10250 ug/L) compared to other studies. Mercury concentration with no significant difference between the miner groups and others. Also, this study found high incidents of neurological symptoms associated with neurotoxicity. The problem with thinking significantly correlated to the age weighted by mercury concentration. Only tremor significantly related to the time living in the mining area. Otherwise, no significant relationship between mercury concentration ,symptoms and time living in the area.
 Recommendation: conducting Interventional study by using chelation therapy, Gold miners should use safety tools, Activation of laws and conventions (MINAMATA convention).

Factors influencing fish mercury concentrations in Iowa rivers.

Fish mercury concentrations have received considerable attention due to human health implications. Fish mercury concentrations are variable within and among systems due to a suite of biotic and abiotic influences that vary among regions and are difficult to predict. Understanding factors associated with variability in fish mercury concentrations would help guide consumption advisories. Mercury concentrations in channel catfish (Ictalurus punctatus, n = 205), flathead catfish (Pylodictis olivaris, n = 123), northern pike (Esox lucius, n = 60), smallmouth bass (Micropterus dolomieu, n = 176), and walleye (Sander vitreus, n = 176) were assessed in ten Iowa rivers and relationships with land use, water chemistry, and fish characteristics were explored. Mercury concentrations were generally low (mean among all species = 0.17 mg/kg, n = 740) but higher in flathead catfish, northern pike, smallmouth bass, and walleye than channel catfish and were positively related to fish length, age, trophic position, and δ13C signatures. Phosphorus, sulfate, and percent open water and grassland were negatively related to fish mercury concentrations, whereas water hardness, nitrogen-ammonia, Human Threat Index, and percent wetland and forest were positively related to fish mercury concentrations. Fish collected from the Paleozoic Plateau ecoregion in northeast Iowa had higher mercury concentrations than other ecoregions in Iowa. Combined, these factors explained 70% of the variation in fish mercury concentrations. This study provides a comprehensive analysis of abiotic and biotic factors influencing fish mercury concentrations in lotic ecosystems at the individual and system scale that will help guide fish consumption advisories.

Mercury contamination levels in the bioindicator piscivorous fish Hoplias aïmara in French Guiana rivers: mapping for risk assessment.

In French Guiana, native populations present high level of mercury contamination, which has been linked to the consumption of contaminated fishes. The goal of this study is to undertake a cartography of mercury contamination levels in fishes from the six main Guiana rivers. The selected species for this study is the ubiquitous piscivorous fish Hoplias aimara. A total number of 575 fishes from 134 discrete fishing sites are regrouped into 51 river sectors. Results from this study permits to rank the six main Guiana rivers by their mean level of contamination: Oyapock (0.548mgkg-1), Comté (0.624mgkg-1), Maroni (0.671mgkg-1), Approuague (0.684mgkg-1), Mana (0.675mgkg-1), and Sinnamary (1.025mgkg-1). The contamination is however not spatially homogenous along each river, and a map of the different levels of mercury contamination in fishes is provided. Sectors of low mean Hg contamination are observed both upstream (0.471mgkg-1) and downstream (0.424mgkg-1), corresponding to areas without any influence of gold mining activities and areas under the influence of estuarine dilution, respectively. Anoxia and gold mining activities are found to be the two main factors responsible for the high mercury concentration in fish muscles. While mean levels of mercury contaminations are higher in anoxia areas (1.029mgkg-1), contaminations induced by gold mining activities (0.717mgkg-1) present the most harmful consequences to human populations. No significant differences in Hg concentrations are observed between 2005 and 2014 for neither a pristine nor a gold mining area, while Hg concentration differences are observed between former (0.550mgkg-1) and current gold mining sites (0.717mgkg-1).

Assessment of Mercury in Diagnostic Biomaterials of Different Population Groups in Urban Areas of the Moscow Region

The results of a survey of different population groups in urban areas of the Moscow Region (industry workers, residents of areas with increased anthropogenic load of mercury and conditionally pristine areas, cohorts of pregnant women and children) to assess the contents of mercury in samples of various diagnostic biomaterials taken during the course of research are presented. Mercury concentrations in venous and umbilical cord blood, urine, hair, and nails were determined by means of instrumental neutron activation analysis and cold vapor atomic absorption spectrometry. Peculiarities of selection, transportation, storage, and preparation for analysis of samples of hair, nails, urine and umbilical venous blood are described. The determined concentrations of mercury in the studied diagnostic biomaterials are compared with normal and thresholds values. Although increased mercury concentrations were observed in some cases, no significant exposure of mercury was evident in general in the study towns. A positive correlation between the degree of consumption of seafood during pregnancy and a high content of mercury in the analyzed diagnostic biomaterials was shown.

Lead and mercury exposure in populations on the banks of the Bogotá River: a multi-method study

This study sought to understand the health problems associated with the presence of lead and mercury in the water of the Bogotá River. A mixed methods study was conducted using interviews, surveys and measurements of zinc protoporphyrin (ZPP) and mercury in blood from 172 individuals. Variables associated with the highest concentrations were identified, as well as the attributes of the cases with increased exposure by means of a qualitative comparative analysis. Interviews reported that river pollution is associated with diseases, although direct exposure to water is rare. River water is widely used for irrigation of crops that are sold in other municipalities. Communities with greater exposure to river water are Tocaima and Girardot. The highest levels of ZPP were observed among those living in these municipalities, did activities at home and performed non-work activities using metals. Increased ZPP levels were associated with depression, nasal bleeding and loss of appetite. The highest concentrations of mercury were found in the inhabitants of Girardot, and were associated with sweating, disorientation, nausea and diarrhea. Low levels of lead and mercury were observed in the study population, although there are specific cases with high social vulnerability that require special attention.

The Concentration of Micronutrients and Heavy Metals in Maternal Serum, Placenta, and Cord Blood: A Cross-Sectional Study in Preterm Birth

Background Preterm birth is still a global burden particularly in Indonesia. The suboptimal concentration of certain micronutrients and heavy metals is hypothesized to play a role in the mechanism of preterm birth. Objective This study aimed to analyze the micronutrients and heavy metals concentrations between subjects with term and preterm birth. Design A cross-sectional study was conducted during January–June 2017 in Cipto Mangunkusumo Hospital and Budi Kemuliaan Hospital, Jakarta, Indonesia. Subjects were divided into term and preterm birth groups. The measured outcomes were maternal serum, placental, and blood cord concentration of zinc, copper, iron, selenium, manganese, mercury, lead, AtRA, and 25(OH)D. Results A total of 51 pregnant women participated in this study. Term group had higher concentration of maternal serum AtRA (0.22 ± 0.07 ng/mL versus 0.12 ± 0.03 ng/mL, p <0.001), higher placental concentration of manganese {0.99 (0.38 – 1.78) μg/g versus 0.42 ± 0.18 μg/g, p <0.001}, iron (252.16 ± 170.61 μg/g versus 78.45 ± 51.73 μg/g, p <0.001), copper {2.96 ± 1.80 μg/g versus 1.62 (0.70 – 3.88) μg/g, p 0.019}, zinc {58.34 (27.88 – 124.05) μg/g versus 28.41 (1.46 – 137.69) μg/g, p 0.011}, selenium (0.31 ± 0.31 ng/g versus 0.14 ± 0.20 ng/g, p 0.024), AtRA {21.7 ± 10.69 ng/g versus 0.7 (0.42 – 5.10) ng/g, p <0.001}, and 25(OH)D {75.84 ± 45.12 ng/g versus 18.00 (5 – 88) ng/g, p <0.001}, lower placental concentration of mercury (0.20 ± 0.17 ng/g versus 20.47 ± 41.35 ng/g, p 0.019) and lead (0.02 ± 0.01 ng/g versus 0.81 ± 1.43 ng/g, p 0.009), and higher cord blood concentration of copper {32.20 (16.30 – 69.60) μg/dL versus 20.60 (5.80 – 53.30) μg/dL, p 0.006} and AtRA (0.16 ± 0.04 versus 0.07 ± 0.01, p <0.001). Conclusion Preterm birth is associated with lower concentrations of micronutrients which play a role in antioxidant mechanism, as well as higher concentration of mercury and lead.

The distribution and accumulation of mercury and methylmercury in surface sediments beneath the East China Sea.

China is a massive mercury emitter, responsible for a quarter of the world's mercury emissions, which transit the atmosphere and accumulate throughout its watercourses. The Changjiang (Yangtze) River is the third largest river in the world, integrating mercury emissions over its 1.8 × 106km2 catchment and channelling them to the East China Sea where they can be buried. Despite its potential global significance, the importance of the East China Sea as a terminal mercury sink remains poorly known. To address this knowledge gap, total mercury and methylmercury concentrations were determined from 51 surface sediment samples revealing their spatial distribution, whilst demonstrating the overall pollution status of the East China Sea. Sedimentary mercury distributions beneath the East China Sea are spatially heterogeneous, with high mercury concentrations (> 25ngg-1) corresponding to areas of fine-grained sediment accumulation. In contrast, some sites of fine-grained sediment deposition have significantly lower values of methylmercury (< 15ngg-1), such as the Changjiang estuary and some isolated offshore areas. Fine-grained particles and organic matter availability appear to exert the dominant control over sedimentary mercury distribution in the East China Sea, whereas in situ methylation serves as an additional control governing methylmercury accumulation. Estimated annual sedimentary fluxes of mercury in the East China Sea are 51 × 106g, which accounts for 9% of China's annual mercury emissions.

THE RESULTS OF THE MONITORING OF THE MERCURY CONTAMINATION WITHIN A MEGAPOLIS

Introduction. Macromycetes include mercury compounds in their metabolism processes. The method for assessing the contamination of the soil layer (topsoil) by mercury by estimating the mercury content in the mushrooms is accessible and sufficiently informative. Mercury is a persistent inorganic ecotoxicant, it enters the human body from the environment. This process requires constant monitoring of the content of this hazardous metal in the environment and the in biomaterials of the human organism. Material and methods. The object of the study was selected bracket macromycetes growing on open soil areas: lawns, boulevards, parks, squares, etc. There were studied representatives from the fungal families as follows: Agaricacea, Boletaceae, Russu-laceae, Coprinaceae. Mushrooms were collected in the stage of sporulation, in the spring-summer-autumn period from 2002 to 2017. The determination of mercury in fungi was performed by atomic absorption method on specialized mercury analyzers of the “Julia” series (detection limit of 1 ng/g, the error of the method is not more than 15%). Mercury content in hair was determined in 1153 St. Petersburg residents aged from 0 to 80 years using atomic emission and mass spectrometry methods with inductively coupled argon plasma on devices Elan 9000 (Perkin Elmer, USA) and Optima 2000 V (Perkin Elmer, USA). Results. The results of the analysis of mushrooms collected in 2017 on one of the green streets of the industrial district of Saint-Petersburg demonstrate a high degree of mercury contamination of the megapolis. Mushrooms (Cinereus comatus) were collected at three locations of Alameda, separated by approximately 100 m, and were analyzed for the content of mercury in them. The following values of mercury in mushrooms were got is a 0.61 mg/kg, 0.83 mg/kg and 0.35 mg/kg. The hair of 1153 inhabitants of St.-Petersburg has been analyzed for mercury content. The highest concentrations of mercury have been established to be set at working population aged 18-64 years. This fact can be explained by the professional activities associated with the contact with mercury and active way of life, particularly with greater frequency of the use in the diet of mushrooms and other products, being potential sources of mercury. Discussion. The performed studies show the mercury concentration to be not only generalized but also stable. The pollution of the territory of St. Petersburg is little different from the pollution of the territories of other cities, where the mercury content in mushrooms is also found to be high in comparison with the permissible level. Conclusion. The obtained data indicate a high stable contamination of the territory of St. Petersburg and its nearest suburbs with mercury. Mercury and its compounds in environmental objects (mushrooms) can present the real danger to the health of the population, therefore there is a need for non-invasive monitoring of the content of mercury in biomaterials of the human organism and environmental objects.

The Primordial Solar Wind as a Sculptor of Terrestrial Planet Formation

Abstract Our solar system is almost entirely devoid of material interior to Mercury’s orbit, in sharp contrast to the multiple Earth masses of material commonly residing within the analogous region of extrasolar planetary systems. Recent work has suggested that Jupiter’s orbital migration early in the solar system’s history fragmented primordial planetary material within the inner solar system. However, the reason for the absence of subsequent planet formation within 0.4 au remains unsolved. Here, we show that leftover debris interior to Mercury’s current orbit was susceptible to outward migration driven by the early Solar wind, enhanced by the Sun’s primordial rapid rotation and strong magnetic field. The ram pressure arising from azimuthal motion of the Solar wind plasma transported ∼100 m-sized objects and smaller from 0.1 au out to the terrestrial planet-forming zone within the suspected ∼30–50 Myr timespan of the Earth’s formation. The mass of material within this size class typically exceeds Mercury, and can rival that of Earth. Consequently, the present-day region of terrestrial planets and the asteroid belt has been supplied by a large mass of material from the innermost, hot solar system, providing a potential explanation for the evidence of high-temperature alteration within some asteroids and the high iron content of Mercury.

Characterization of solid and vapor products from thermochemical conversion of municipal solid waste woody fractions

The ever-increasing consumption of material goods with economic growth is resulting in an increasing generation of municipal solid waste (MSW) and the rapid filling of landfills. Fractions of municipal solid waste containing wood-based products have the potential to be used for the development of value added products. In this paper we produced and characterized biochar and pyrolysis vapors from municipal solid waste (MSW) woody fractions to demonstrate their suitability towards soil amendments. Carbonization work focused on compost overs, molded wood pallets, treated wood, sawmill cut ends, wood derived fuels, furniture, painted wood, plywood, oriented strand board and particle boards from Washington State recycling facilities. The goal of this research is to use these biochars as soil amendments; however, there are concerns with both the potential presence of condensed organic pollutants and trace metals. The presence of trace metals and polycyclic aromatic hydrocarbons (PAH) in all the biochars produced were examined. GC-MS analyses of liquid extracts did not reveal the presence of soluble PAH compounds. High concentrations of mercury (Hg) and arsenic (As) were found in the biochar made from painted wood and treated wood, respectively. Among the methods tested for the removal of trace metals, acid washing was found to be the most effective. The volatiles released from the analyzed MSW fractions were also analyzed in Py-GC-MS studies. Among these volatile compounds, many contained Cl, N, or S, which could be potential sources of pollution if the pyrolysis vapors are combusted.

The effect of circulating fluidized bed boiler load on the emission of mercury

The paper deals with the determination of mercury balance for a hard coal-fired circulating fluidized bed boiler operated at various loads (i.e. 100%, 75% and 50% of the Maximum continuous rating, MCR). The research was focused on the determination of the mercury balance by providing data on Hg content in fuel, limestone sorbent, and in the combustion by-products (fly ash and bottom ash). Furthermore, the concentration of mercury in the flue gas in two zones i.e. upstream and downstream the electrostatic precipitator (ESP) were also determined in order to assess the effectiveness of the ESP in mercury reduction. For the calculation of the Hg balance both gaseous mercury species, Hg0, and oxidized mercury, Hg2+, were taken into consideration.The results indicated that over 95% of the mercury was fed into the boiler system with coal and just less than 5% with limestone used for ‘dry’ desulfurization of the flue gas. As for the boiler output, very high mercury content was determined in the fly ashes, while just a minor part (a few percent of the total mercury input) was found in the bottom ashes. The shares of Hg0 and Hg2+ mercury were affected by boiler load.

Effective removal of mercury from aqueous streams via electrochemical alloy formation on platinum

Retrieval of mercury from aqueous streams has significant environmental and societal importance due to its very high toxicity and mobility. We present here a method to retrieve mercury from aqueous feeds via electrochemical alloy formation on thin platinum films. This application is a green and effective alternative to traditional chemical decontamination techniques. Under applied potential, mercury ions in solution form a stable PtHg4 alloy with platinum on the cathode. A 100 nanometres platinum film was fully converted to a 750 nanometres thick layer of PtHg4. The overall removal capacity is very high, > 88 g mercury per cm3. The electrodes can easily be regenerated after use. Efficient and selective decontamination is possible in a wide pH range, allowing processing of industrial, municipal, and natural waters. The method is suited for both high and low concentrations of mercury and can reduce mercury levels far below the limits allowed in drinking water.

Field Assessment of Colorado pikeminnow Exposure to Mercury Within Its Designated Critical Habitat in Colorado, Utah, and New Mexico

Mercury contamination in freshwater fish is widespread across North America, including the western United States. Atmospheric mercury from both natural and manmade emissions deposits into watersheds and, through methylation and biomagnification, accumulates in aquatic food webs. Highest mercury concentrations are found in predatory fish. The endangered Colorado pikeminnow (Ptychocheilus lucius) is a long-lived, top-level piscivore endemic to the Colorado River basin. Mercury exposure to Colorado pikeminnow and another native fish species, the roundtail chub (Gila robusta), was assessed by analyzing muscle tissues collected using a nonlethal technique. Mercury concentrations in Colorado pikeminnow > 400-mm long, captured from critical habitat throughout the species’ present range, exceeded the tissue threshold-effect level of 0.2 µg/g wet weight (WW) for whole body fish (0.31 µg/g WW in muscle) recommended to protect fish from injury. Mercury is a neurotoxin and endocrine disruptor, and impacts to fish may include reduced ability to avoid predators, secure food, and reproduce. The highest mercury concentrations were found in both Colorado pikeminnow and roundtail chub collected from the White River, a tributary to the Green River. Colorado pikeminnow from the White and Green rivers had the highest mean mercury concentrations and the lowest mean relative body conditions. Exposure to high mercury concentrations may act in concert with other threatening factors to compromise Colorado pikeminnow population viability and eventual recovery.

Mercury assessment, macrobenthos diversity and environmental quality conditions in the Salado Estuary (Gulf of Guayaquil, Ecuador) impacted by anthropogenic influences

Water and sediment quality, macrobenthos diversity and mercury levels were assessed in the Salado Estuary, Gulf of Guayaquil (Ecuador) during 2008, 2009 and 2014. Severe hypoxia, anoxia and large fluctuations of salinity occurred in an impacted sector within Guayaquil city relative to a mangrove area within the Salado Mangroves Faunal Production Reserve. Significant inter-site and temporal differences were observed for dissolved oxygen, salinity, total dissolved solids, percentage of silts and clays, and species diversity. Macrobenthos' species richness for both sectors was greater during 2008. Sediments revealed high concentrations of total mercury (THg) (1.20–2.76 mg kg−1 dw), exceeding Ecuador's SQG (0.1 mg kg−1 dw). Sediment THg were significantly lower in 2014 than 2008/09. Biota sediment sccumulation factor values for mussels (3.0 to 34), indicate high bioaccumulation potential from mercury-contaminated sediments. This work highlights the need to develop stronger environmental policies to protect the Salado Estuary from anthropogenic stressors.

Factors affecting the concentration and distribution of gaseous elemental mercury in the urban atmosphere of downtown Toronto

Atmospheric gaseous elemental mercury (GEM) and meteorological parameters were simultaneously monitored at two building rooftops in downtown Toronto, Canada from Oct. 2015 to Oct. 2016. The two buildings are ∼136 m apart, one is an office building (60 m tall) and the other (30 m tall) mainly contains chemistry and biology laboratories, offices and classrooms. The average mercury concentrations were found to be 1.46 ± 0.54 ng/m3 and 1.78 ± 0.89 ng/m3 for the 60 m and 30 m sites, respectively. Analysis of the data reveals that sporadic events of high mercury concentration are related to local sources; that the higher level of GEM at the 30 m site resulted from a combination of local sources and weaker mixing of air at lower height; regional sources contributed to the loading of GEM in urban atmosphere.Comparing the data set with a data set collected in 2004 from the same location revealed that the average atmospheric GEM concentration in downtown Toronto dropped from 4.5 ng/m3 to 1.78 ng/m3 (60% decrease). Decreases in GEM were also observed in the data reported by CAMNet over the same period in rural and remote areas but to a lesser extent (10.5 and 13.9% respectively). The decrease is in line with the key national and provincial policies on mercury use, emission control and management that have been enacted since 2004.