Reduction In Mercury Concentration Research Articles

Ultra-Efficient Removal of Mercury from Contaminated Water using Selected Phenylimidazole Derivatives

Heterocycles, including imidazole derivatives, are important chemicals due to their structural similarity to active natural molecules. This study explored the utilization of phenylimidazole derivatives for mercury removal from aqueous solutions. Three derivatives were tested, including one harboring a sulfhydryl functional group, thus offering distinct mercury-binding capabilities. Mercury binding experiments revealed modest mercury binding by two derivatives. However, extraordinary efficiency of mercury binding by the sulfhydryl-bearing compound was demonstrated through a reduction in mercury concentrations in pure water by 43-fold in just 15 min and decreasing below the analytical detection limit with prolonged exposure (30 min). Moreover, the ultra-efficiency of mercury binding was demonstrated by a capability to reduce mercury concentrations even in highly contaminated environmental water sample by a factor exceeding 1200-fold in 20 h, using minimal amounts of the compound. This phenylimidazole derivative exhibited comparable efficiency in binding mercury from authentic environmental water samples, hinting at practical applications for real-world remediation efforts. Kinetic investigations showed a pseudo-first order reaction with a rate constant of 0.26 min−1 and half-life of 2.69 min that governs mercury binding to this phenylimidazole derivative. These findings underscore the potential of the sulfhydryl-containing phenylimidazole derivative, as swift and effective binding material for aqueous mercury removal. Its rapid action, coupled with binding efficiency, suggests a promising material for addressing mercury contamination in highly contaminated environmental water samples.

Effect on reclamation on mercury concentration in groundwater: a case study of Lubo\u0144 Chemical Plant (Pozna\u0144, Poland)

Luboń Chemical Plant (Poland), founded in 1914, is the place where many products such as superphosphate, hydrofluoric acid, sulfuric acid, aluminum fluoride, potassium fluoroborate, vanadium catalyst and other chemicals and post-production waste have been produced and stored. The main products manufactured by Luboń Chemical Plant are powdered superphosphate (obtained from apatite) and sulfuric acid (obtained from pyrite) The aim of the study was to determine the impact of the former post-crystallization leachate disposal site located in the area of Luboń Chemical Plant on groundwater contamination with mercury. Groundwater samples were collected from 12 piezometers in the area of the plant or in close vicinity to the plant, and from one piezometer located 2.5 km north of the study area, i.e., from Poznań-Dębina groundwater intake, in the years 2007–2014. Total mercury concentration in groundwater from Luboń was high in all samples, and ranged from 10.9 to 2818 ng L− 1 (average 335 ± 509 ng L− 1, median = 158 ng L− 1). The highest mercury concentration values were measured in piezometer no. 7, located in close proximity to the production facilities of the chemical plant, and they equaled 2604 ng L− 1 in 2007 and 2818 ng L− 1 in 2008. The lowest concentration of mercury (10.9 ng L− 1) was determined in 2014, in a sample taken from piezometer no. 13 located at the water intake for the agglomeration of Poznań (Poznań-Dębina). Based on the obtained results, two sources of groundwater pollution were found: (1) Luboń Chemical Plant, and (2) former post-crystallization leachate disposal site. A decrease in mercury concentrations with increasing distance of piezometers from the pollution sources was reported. Moreover, a reduction in mercury concentration over the years has been observed, especially after completion of reclamation and remediation works in the area of Luboń Chemical Plant in 2008. Despite the negative impact of the plant on groundwater quality measured in the piezometer located at the water intake Poznań-Dębina, the drinking water quality guidelines (1000 ng L− 1) was not exceeded.

Mitigation of Mercury Contamination in an Ore Collection

The National Rock and Ore Collection at the Smithsonian Institution’s National Museum of Natural History includes mercury ore specimens stored at its Museum Support Center in Suitland, Maryland. Two decades after the ore collection was moved from historic metal clad wooden cabinets with felt gaskets to modern steel cabinets with neoprene foam gaskets, it became apparent that elemental mercury vapor generated from the specimens was accumulating within the storage units, creating visible mercury deposits on cabinet interior surfaces and drawers, as well as the paperboard storage trays and paper specimen labels inside the drawers. Concerns were raised about the potential health hazard to users of the collection, as well as potential cross-contamination of non-mercury-bearing specimens, housing materials and equipment. The Museum’s collection manager, conservator, and industrial hygienist developed three phases of mitigation strategies, which were applied and analyzed for effectiveness between 2011 and 2016. The first phase involved creating special vapor barrier packaging for each mercury ore using Marvelseal®, welded on three sides by the supplier, and frame sealing tape to secure the fourth side; disposal of all trays and replacement of trays for the non-mercury-bearing specimens; extensive cleaning of the cabinet interiors using Mercury Absorb Sponges; and lining each drawer and cabinet with MicroChamber scavenger sheets. Utilizing a Jerome Mercury Vapor Analyzer, measurements indicated a 40-50% reduction in mercury concentrations within the affected cases. There were still visible residual mercury deposits, so a second, more rigorous phase of cleaning was conducted on all accessible interior cabinet and drawer surfaces, paying special attention to unpainted metal hardware. A modified solution of Lugol’s iodine was used, followed by isopropyl alcohol wipes to remove the residual iodine solution. This second phase led to a further reduction in mercury vapor of 60-80% from the original measurements. The cases were securely closed for one year, and subsequent measurements indicated a significant re-accumulation of mercury vapor. During the third phase of mitigation, zeolite scavenger sheets were inserted between drawers and over bagged specimens, and MicroChamber sheets from the second phase were replaced. This resulted in mercury vapor concentration reductions back to 60-80% of the original measurements. However, the median concentration still exceeded the conservative occupational health exposure limit of 0.025 mg/M3. Subsequent investigation suggests that residual mercury residue on inaccessible interior cabinet surfaces is the limiting factor preventing complete and permanent mitigation.

Dietary selenium protect against redox-mediated immune suppression induced by methylmercury exposure

The antagonism between selenium (Se) and mercury (Hg) has been widely recognized, however, the protective role of Se against methylmercury (MeHg) induced immunotoxicity and the underlying mechanism is still unclear. In the current study, MeHg exposure (0.01mM via drinking water) significantly inhibited the lymphoproliferation and NK cells functions of the female Balb/c mice, while dietary Se supplementation (as Se-rich yeast) partly or fully recovered the observed immunotoxicity, indicating the protective role of Se against MeHg-induced immune suppression in mice. Besides, MeHg exposure promoted the generation of the reactive oxygen species (ROS), reduced the levels of nonenzymic and enzymic antioxidants in target organs, while dietary Se administration significantly diminished the MeHg-induced oxidative stress and subsequent cellular dysfunctions (lipid peroxidation and protein oxidation). Two possible mechanisms of Se’s protective effects were further revealed. Firstly, the reduction of mercury concentrations (less than 25%, modulated by Se supplementation) in the target organs might contribute, but not fully explain the alleviated immune suppression. Secondly and more importantly, Se could help to maintain/or elevate the activities of several key antioxidants, therefore protect the immune cells against MeHg-induced oxidative damage.

Effect of heavy metals on the stabilization of mercury(II) by DTCR in desulfurization solutions

Several heavy metals, including Cu2+, Ni2+, Pb2+, and Zn2+, were investigated in simulated desulfurization solutions to evaluate their interferences with Hg2+ during the reaction with dithiocarbamate type chelating resin (DTCR). Appropriate DTCR dosage and the effect of pH were also explored with respect to restoration of high Hg2+ precipitation efficiency and reduction of mercury concentrations. The experimental results suggested that increasing heavy metal concentration inhibited Hg2+ precipitation efficiency to a considerable extent and the inhibition order of the four heavy metals was Cu2+>Ni2+>Pb2+>Zn2+. However, the coordination ability was closely related to the configuration and the orbital hybridization of each metal. In the cases of Cu2+ and Pb2+, increased DTCR dosage was beneficial to Hg2+ precipitation, which could lay the foundation of practical applications of DTCR dosage for industrial wastewater treatment. The enhanced Hg2+ precipitation performance seen for increasing pH might have come from the deprotonation of sulfur atoms on the DTCR functional groups and the formation of metal hydroxides (M(OH)2, M=Cu, Pb, Hg).

Simulation of flow and mercury transport in Upper East Fork Poplar Creek, Oak Ridge, Tennessee

AbstractAs a result of nuclear processing activities started back in the 1950s, the environment in the vicinity of the Y‐12 National Security Complex (Y‐12 NSC) in Oak Ridge, Tennessee, and surrounding watersheds has been contaminated by nearly 1,000 tons of elementary mercury. To comply with the state and federal surface water quality standards, a significant reduction in mercury concentration to parts‐per‐trillion levels has been proposed. In order to analyze the mercury cycle in the environment and provide forecasting capabilities for the flow and transport of mercury within the Upper East Fork Poplar Creek (UEFPC) watershed, an integrated surface and subsurface flow and transport model has been developed using the hydrodynamic and transport numerical package, MIKE, developed by the Danish Hydraulic Institute. The model has been constructed and calibrated using an extensive collection of historical records (i.e., hydrological data, and mercury concentration measurements in groundwater, soil, and sediment) obtained from the Oak Ridge Environmental Information System database. Daily fluctuations in stream flow, as a result of scattered rainfall, flooding, and flow augmentation, resuspend the contaminated streambed sediments and/or erode the polluted streambank soil and provide a secondary source of mercury to the creek. In order to investigate the significance of sediment‐mercury interactions on the fate and transport of mercury within the UEFPC study domain, simulations were performed for two different cases (i.e., with and without consideration of sediment‐mercury interactions). Computed total suspended solids and mercury concentrations at the integration point of the creek are compared with the corresponding historical records in both cases. As confirmed by the numerical simulations, a substantial portion of the mercury detected in the river is likely in the form of sediment particle–bound mercury (i.e., mercury particulates). © 2012 Wiley Periodicals, Inc.

Risk-benefit analysis of fish consumption: Fatty acid and mercury composition of farmed southern bluefin tuna, Thunnus maccoyii

The docosahexanoic acid (DHA) and eicosapentaenoic acid (EPA) contents and total mercury concentration were measured in whole tissue composites of all edible tissues of wild caught and farmed southern bluefin tuna ( Thunnus maccoyii, SBT) and each of the marketed tissue cuts (akami, chu-toro and o-toro) of these fish. Rapid lipid accumulation during culture resulted in a net reduction in mercury concentration of SBT composite tissues and an increase in the concentration of the dietary essential fatty acids. Moreover, the increased affinity of lipid for certain tissue cuts (o-toro) over that of others (e.g. akami), resulted in cross carcass variation in the mercury concentration of fish muscular tissue. Results highlight the potential for farming to be used as a tool to improve the flesh quality of fish species which could otherwise provide limited dietary essential fatty acids to consumers and potentially contain elevated contaminant levels.

Ecological risk of methylmercury to piscivorous fish of the Great Lakes region

Contamination of fish populations with methylmercury is common in the region of the Laurentian Great Lakes as a result of atmospheric deposition and methylation of inorganic mercury. Using fish mercury monitoring data from natural resource agencies and information on tissue concentrations injurious to fish, we conducted a screening-level risk assessment of mercury to sexually mature female walleye (Sander vitreus), northern pike (Esox lucius), smallmouth bass (Micropterus dolomieu), and largemouth bass (Micropterus salmoides) in the Great Lakes and in interior lakes, impoundments, and rivers of the Great Lakes region. The assessment included more than 43,000 measurements of mercury in fish from more than 2000 locations. Sexually mature female fish that exceeded threshold-effect tissue concentrations of 0.20 μg g(-1) wet weight in the whole body occurred at 8% (largemouth bass) to 43% (walleye) of sites. Fish at 3% to 18% of sites were at risk of injury and exceeded 0.30 μg g(-1) where an alteration in reproduction or survival is predicted to occur. Most fish at increased risk were from interior lakes and impoundments. In the Great Lakes, no sites had sexually mature fish that exceeded threshold-effect concentrations. Results of this screening-level assessment indicate that fish at a substantive number of locations within the Great Lakes region are potentially at risk from methylmercury contamination and would benefit from reduction in mercury concentrations.

Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon

An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR–mercury interactions and Hg–S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. μ-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg–Cl and Hg–S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH.

Mercury Capture within Coal-Fired Power Plant Electrostatic Precipitators: Model Evaluation

Efforts to reduce anthropogenic mercury emissions worldwide have recently focused on a variety of sources, including mercury emitted during coal combustion. Toward that end, much research has been ongoing seeking to develop new processes for reducing coal combustion mercury emissions. Among air pollution control processes that can be applied to coal-fired boilers, electrostatic precipitators (ESPs) are by far the most common, both on a global scale and among the principal countries of India, China, and the U.S. that burn coal for electric power generation. A previously reported theoretical model of in-flight mercury capture within ESPs is herein evaluated against data from a number of full-scale tests of activated carbon injection for mercury emissions control. By using the established particle size distribution of the activated carbon and actual or estimated values of its equilibrium mercury adsorption capacity, the incremental reduction in mercury concentration across each ESP can be predicted and compared to experimental results. Because the model does not incorporate kinetics associated with gas-phase mercury transformation or surface adsorption, the model predictions representthe mass-transfer-limited performance. Comparing field data to model results reveals many facilities performing at or near the predicted mass-transfer-limited maximum, particularly at low rates of sorbent injection. Where agreement is poor between field data and model predictions, additional chemical or physical phenomena may be responsible for reducing mercury removal efficiencies.

Empirical models to identify mechanisms driving reductions in tissue mercury concentration during culture of farmed southern bluefin tuna Thunnnus maccoyii

Two empirical models are presented to elucidate the mechanisms driving reductions in the mercury concentration of southern bluefin tuna (SBT) during culture. Model 1 predicts temporal fluctuations in mercury concentration in response to growth dilution. Model 2 predicts the combined effects of growth dilution and linear mercury accumulation. Model 2 was found to be the more accurate model. Over a typical farming period of 136 days, growth dilution resulted in a reduction in mean mercury concentration of SBT edible tissues from 0.51 mg/kg down to 0.33 mg/kg. Extended culture beyond 136 days resulted in an increase in mercury concentration due to the combined effects of mercury accumulation and seasonal lipid depletion. Results indicate that under current industry practice, cultured SBT can be consumed twice as frequently as that of wild caught SBT while maintaining total dietary mercury intake below national recommendations.

Long-term effects of mercury in a salt marsh: Hysteresis in the distribution of vegetation following recovery from contamination

During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh.

Mercury removal by immobilized algae in batch culture systems

The accumulation and volatilization of mercury by non-immobilized and immobilizedChlorella emersonii have been studied in batch culture systems. Reduction in the mercury concentration in the growth medium by non-immobilized cells was highly dependent on inoculum density, whilst reduction in mercury concentration by immobilized cells was rapid at all inoculum densities. Mercury accumulation by immobilized cell biomass was significantly greater than by non-immobilized cells with 106 and 105 cells bead−1 or ml−1. Volatilization of mercury by non-immobilized cell systems was greatest at higher inoculum densities, whereas more mercury was volatilized from immobilized cell systems at lower inoculum densities, and was greatest with unstocked alginate beads. Thus, in immobilized systems, mercury removal from solution is complex and involves mercury accumulation by the cells and volatilization by the matrix and cells. Further studies of mercury accumulation and volatilization by unstocked immobilization matrices revealed that agarose volatilized much less mercury than alginate or agar. The precise mechanism of mercury volatilization by alginate remains unclear, though it is thought to be a chemical effect.

Retention of Mercury in the Muscle of Yellow Perch (Perca flavescens) and Rock Bass (Ambloplites rupestris)

Abstract Mercury-contaminated yellow perch (Perca flavescens) and rock bass (Ambloplites rupestris) were collected from Lake St. Clair and stocked in two earthern ponds in September 1970. Twenty-six months later, concentrations of total mercury in the fillets had declined 53% in the yellow perch and 59% in the rock bass; however, the mean weight of the fish increased 88 and 183%, respectively, during the same period. All of the reduction in mercury concentrations was attributable to dilution by growth. Slight discrepancies between the theoretical and observed reduction of mercury concentrations suggest an initial redistribution of residues from other tissues to the muscle and a continued incorporation of background amounts of mercury during growth.

Levels of mercury in urine correlated with the use of skin lightening creams.

The pattern of use of mercury-containing skin lightening creams in a group of young healthy African women was strikingly reflected by the excretion of mercury in urine. Although the levels of mercury in urine frequently associated with manifestations of systemic toxicity were not observed, the mean concentration of mercury in urine, at random sampling, was significantly more than the acceptable upper limit of normal in the group of subjects using mercury-containing skin lightening creams at the time of study. When use of these preparations was discontinued, progressive reduction in mercury concentration in urine Was manifest. Continued use, however, resulted in a variable pattern of subsequent excretion of mercury in urine for which a probable explanation is presented. No definite evidence o of renal damage was obtained, and in particular there were no stigmata of the nephrotic syndrome. The previously published data concerning the association of the nephrotic syndrome with exposure to mercury is reviewed. It is felt that in this respect the subjects of this study constitute a vulnerable population.