Metallomics Analysis for Assessment of Toxic Metal Burdens in Infants/Children and Their Mothers: Early Assessment and Intervention Are Essential.

Accumulation of toxic metals in infants/children is of serious concern worldwide, from the viewpoint of their harmful effects on the normal growth and development. This metallomics study investigates the extent of toxic metal burdens in infants/children and the relationship to those in their mothers for 77 child/mother pair subjects. For mercury, its geometric mean concentration in infants/children was of similar level to that in their mothers, and a high-significant close correlation was observed between infants/children and their mothers (ß = 0.758, r = 0.539, p < 0.0001). A significant but less intimate mother/child relationship was observed for arsenic (ß = 0.301, r = 0.433), lead (ß = 0.444, r = 0.471) and aluminum (ß = 0.379, r = 0.451). Remarkably, the burden levels of lead, cadmium and aluminum in infants/children were approximately three times higher than those in their mothers (p < 0.0001), and the burden levels in some individuals were several tens of times higher than in the mothers. In contrast, some essential metal levels such as zinc, magnesium and calcium in infants/children were significantly lower than those in their mothers, and 29 individuals (37.7%) in the child subjects were estimated to be zinc-deficient. In addition, significant inverse correlations were observed between zinc and lead (r = -0.267, p = 0.019), and magnesium and arsenic (r = -0.514, p < 0.0001). These findings suggest that these toxic metal burdens and essential metal deficiencies in infants/children are of serious concern for their neurodevelopment, indicating that the early assessment and intervention are crucial. It is expected that larger epidemiological and intervention studies will provide a reasonable and essential pathway for intervention of neurodevelopment disorders.

Ultrasonic-assisted recycling of Nile tilapia fish scale biowaste into low-cost nano-hydroxyapatite: Ultrasonic-assisted adsorption for Hg2+ removal from aqueous solution followed by "turn-off" fluorescent sensor based on Hg2+-graphene quantum dots.

This study was planned to recycle calcium and the phosphorus-rich Nile tilapia fish scale biowaste into nano-hydroxyapatite (FHAP), using ultrasonic-assisted extraction of calcium and phosphorus from fish scales, which was optimized in term of extraction time, acid concentration, extraction temperature, and ultrasonic power. These two elements were determined simultaneously by inductively coupled plasma atomic emission spectrometry and the FHAP phase was formed upon addition of the extracted element solution in alkaline medium using homogenous precipitation assisted with ultrasound energy. The FHAP adsorbent was characterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller. A combination of FHAP and the ultrasonic method was then used to remove Hg2+ from aqueous solution. Four significant variables affecting Hg2+ removal, namely, adsorbent dosage, pH, ultrasonic power, and adsorption time, were studied. The results exhibited that the optimal conditions for maximizing the removal of Hg2+ were 0.02 g adsorbent dosage, pH 8, 0.4 kW ultrasonic power, 20 min adsorption time, and 30 °C adsorption temperature. The sorption mechanism of Hg2+ was revealed by isotherm modeling, indicating that FHAP adsorbent has a potential for Hg2+ removal in aqueous media with the maximum adsorption capacity being 227.27 mg g-1. This adsorption behavior is in agreement with the Langmuir model as reflected by a satisfactory R2 value of 0.9967, when the kinetics data were fitted with pseudo-second-order. Therefore, the FHAP could be an alternative adsorbent for the ultrasonic-assisted removal of Hg2+ at very high efficiency and within a very short period of time.

Efficient removal of mercury from aqueous solutions and industrial effluent.

The objective of this study was to examine the ability of a solid waste produced during beneficiation of ornamental rocks to remove mercury (Hg) from an industrial effluent and aqueous solutions under various conditions. Batch studies have been carried out by observing the effects of pH, concentration of the adsorbate, contact time, and so on. Various sorption isotherm models such as Langmuir, Freundlich, and Tóth have been applied for the adsorbent. Film and intraparticle diffusion were both found to be rate-limiting steps. Adsorption was properly described by the Freundlich model (capacity constant of 0.3090 (mg g(-1))(mg L(-1))(-1/n) and adsorption intensity indicator of 2.2939), which indicated a favorable sorption and encouraged subsequent studies for treatment of Hg-containing industrial effluent. Industrial effluent treatment efficiency reached Hg removals greater than 90% by using ornamental rock solid waste (ORSW). Besides, desorption studies indicated that the maximum recovery of mercury was 100 ± 2% for 1 mol L(-1) HNO3 and 74 ± 8% for 0.1 mol L(-1) HNO3. The ORSW could be reused thrice without significant difference on the Hg removal rate from industrial effluent. These findings place ORSW as a promising efficient and low-cost adsorbent for the removal of Hg from aqueous solutions and industrial effluent.

A low-cost and simple paper-based microfluidic device for simultaneous multiplex determination of different types of chemical contaminants in food.

It is difficult to carry out multiple detection of different type of chemicals because of the different chemical microenvironment requirements. Herein, a low-cost and simple paper-based microfluidic device integrated with fluorescence labeled single-stranded DNA (ssDNA) functionalized graphene oxide sensor was developed for the multiplex determination of different types of chemical contaminants in food. In this work, Cy5 labeled corresponding functional ssDNA for different analytes associated with graphene oxide (ssDNA-GO) were employed as core detection sensors to sensitively report the presence of the different type of chemicals as well as enlarge the chemical compatibility, which made it possible to simultaneous detect multiple chemicals under a same chemical microenvironment. Paper microfluidic device can be easily fabricated and paper substrate also facilitated the integration of ssDNA-GO sensors via physical absorption. This device has been successfully applied in multiplex detection of heavy metal mercury (II) ion (Hg(2+)) and silver (I) ion (Ag(+)) and aminoglycoside antibiotics residues in food. It also provided enormous potential for applications of environmental monitoring and clinical diagnosis.

Optimisation of the supercritical extraction of toxic elements in fish oil.

This study aims to optimise the operating conditions for the supercritical fluid extraction (SFE) of toxic elements from fish oil. The SFE operating parameters of pressure, temperature, CO2 flow rate and extraction time were optimised using a central composite design (CCD) of response surface methodology (RSM). High coefficients of determination (R²) (0.897-0.988) for the predicted response surface models confirmed a satisfactory adjustment of the polynomial regression models with the operation conditions. The results showed that the linear and quadratic terms of pressure and temperature were the most significant (p < 0.05) variables affecting the overall responses. The optimum conditions for the simultaneous elimination of toxic elements comprised a pressure of 61 MPa, a temperature of 39.8ºC, a CO2 flow rate of 3.7 ml min⁻¹ and an extraction time of 4 h. These optimised SFE conditions were able to produce fish oil with the contents of lead, cadmium, arsenic and mercury reduced by up to 98.3%, 96.1%, 94.9% and 93.7%, respectively. The fish oil extracted under the optimised SFE operating conditions was of good quality in terms of its fatty acid constituents.

Preconcentration of total mercury from river water by anion exchange mechanism.

A simple and cheap analytical technique was developed for the measurement of total mercury in river water samples using inductively coupled plasma-mass spectrometry (ICP-MS). It is based on the direct complexation of mercury ions using iodide and a cationic surfactant in water for its subsequent solid-phase extraction. Mercury ions are retained on the silica phase as ion pairs in the presence of iodide ions and dodecyltrimethylammonium bromide. Parameters having influential influence on the retention of Hg(II) were investigated: sample flowrate, eluent type, sample volume, iodide and surfactant concentrations. The retained mercury ions are stripped off from silica phase using 10 mL of 8 mol L(-1) HNO3 and quantified by ICP-MS. An enrichment factor of 50 was achieved with a maximum adsorption capacity of 718 µg Hg(II) g(-1). The limit of detection of Hg(II) was 8 pg mL(-1). The developed method was applied for the determination of total mercury in river and tap-water samples.

Assessment of modified matrix solid-phase dispersion as sample preparation for the determination of CH3Hg+ and Hg2+ in fish.

This paper reports, for the first time, the development of an analytical method employing modified matrix solid-phase dispersion (MSPD) for the extraction of CH3Hg(+) and Hg(2+) species from fish samples. Separation and determination of mercury species were performed by gas chromatography coupled to mass spectrometry (GC/MS). Important MSPD parameters, such as sample mass, type and mass of solid support, concentration of extraction solution (HCl and NaCl), and stirring time, were investigated by the response surface methodology. The derivatization step and the separation of mercury species were also evaluated for the determination by GC/MS. Quantitative recoveries were obtained with 0.2 g of fish sample, 0.5 g of SiO2 as the solid support, 0.5 mol L(-1) NaCl and 4.2 mol L(-1) HCl as the extraction solution, and 1 min stirring time. The MSPD method showed to be suitable for the extraction and determination of mercury species in certified reference materials of dogfish liver (DOLT-3) and dogfish muscle (DORM-2). It had good agreement (about 99%) with the certified values, and the relative standard deviation was lower than 9.5%. The limits of detection were 0.06 and 0.12 µg g(-1), for CH3Hg(+) and Hg(2+), respectively. A matrix effect was observed, and the quantification was carried out by the matrix-matched calibration. The method was applied to tuna fish ( Thunnus thynnus ), angel shark ( Squatina squatina ), and guitarfish ( Rhinobatos percellens ) samples. The results of the mercury speciation by MPSD and GC/MS were compared to the total mercury concentration determined by flow injection cold vapor generation inductively coupled plasma mass spectrometry, after microwave-assisted digestion. Agreement ranged from 102% to 105%.

Chemiluminescence assay for the sensitive detection of iodide based on extracting Hg2+ from a T-Hg(2+)-T complex.

A simple and sensitive chemiluminescence assay for iodide (I(-)) detection was reported, which was based on iodide extracting Hg(2+) from DNA featuring a stem-loop structure containing T-Hg(2+)-T. Specifically, Hg(2+) induced random coiled G-rich single-strand DNA to form a stem-loop structure containing T-Hg(2+)-T. Because the binding of Hg(2+) and I(-) is much stronger than that of Hg(2+) and thymine (T), I(-) could extract Hg(2+) from the stem-loop structure, releasing the DNA, which then bound with K(+) and transformed into a K(+)-stabilized G-quadruplex (with hemin as a cofactor), which catalyzed the H(2)O(2)-mediated oxidation of luminol. The produced chemiluminescence as a sensing signal was applied to sensitively and selectively detect iodide with a detection limit of 12 nM. This system exhibited the first DNAzyme-based iodide sensor. Finally, the sensor was successfully applied for iodide detection in real lake water samples.

Determination of methylmercury in marine fish from coastal areas of Zhejiang, China.

The concentration of methylmercury (MMC) and total mercury (TMC) in marine fishes (five species) frequently consumed in the coastal areas of Zhejiang province, China, was determined. The method of high-performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) with the microwave-assisted extraction was used for the MMC determination. TMC was analysed by a direct mercury analyser. MMC and TMC concentrations in five fish species ranged from 53 to 158 µg kg⁻¹ and 60 to 172 µg kg⁻¹, respectively. The proportion of MMC levels in TMC was greater than 80%. The highest MMC and TMC levels were found in Hairtail.

Compact fluorescent lights and the impact of convenience and knowledge on household recycling rates.

Increased energy costs, social marketing campaigns, public subsidies, and reduced retail prices have dramatically increased the number of compact fluorescent lights (CFLs) installed worldwide. CFLs provide many benefits, but they contain a very small amount of mercury. Given the billions of CFLs in use worldwide, they represent a significant source of mercury unless CFLs are recycled and the mercury recovered in an environmentally sound manner. In the state of Maine (northeast United States), despite mandated recycling of CFLs and availability of free CFL recycling, the household CFL recycling rate is very low. A study was undertaken to identify the primary factors responsible for low recycling. The first step was to survey householders who use CFLs. The 520 survey responses indicated that insufficient knowledge regarding recycling and inconvenience of the collection system are the two primary factors for the low recycling rate. To validate these findings, the second step was an examination of the current collection system to assess (a) the knowledge requirements necessary for recycling and (b) the convenience of the collection system. The results of this examination validated that knowledge requirements were excessively difficult to fulfill and the collection system is not sufficiently convenient. Based on these results, waste managers should focus on increasing convenience and simplifying access to information when designing or improving household collection and recycling of CFLs.

Hg(II) removal from water by chitosan and chitosan derivatives: a review.

Mercury (Hg) is one of the most toxic heavy metals commonly found in the global environment. Its toxicity is related to the capacity of its compounds to bioconcentrate in organisms and to biomagnify through food chain. A wide range of adsorbents has been used for removing Hg(II) from contaminated water. Chitosan is obtained by alkaline deacetylation of chitin. The adsorption capacity of chitosan depends on the origin of the polysaccharide, and on the experimental conditions in the preparation, that determine the degree of deacetylation. A great number of chitosan derivatives have been obtained by crosslinking with glutaraldehyde or epichlorohydrin among others or by grafting new functional groups on the chitosan backbone with the aim of adsorbing Hg(II). The new functional groups are incorporated to change the pH range for Hg(II) sorption and/or to change the sorption sites in order to increase sorption selectivity. The chemical modification affords a wide range of derivatives with modified properties for specific applications. Hg(II) adsorption on chitosan or chitosan derivatives is now assumed to occur through several single or mixed interactions: chelation or coordination on amino groups in a pendant fashion or in combination with vicinal hydroxyl groups, electrostatic attraction in acidic media or ion exchange with protonated amino groups. This review reports the recent developments in the Hg(II) removal in waste water treatment, using chitosan and its derivatives in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan and chitosan derivatives under different experimental conditions is reported to help to compare the efficacy of the Hg(II) removal process. A comparison with the adsorption capacity of other low-cost adsorbents is also tabled.

Development of a regenerable system employing silica-titania composites for the recovery of mercury from end-box exhaust at a chlor-alkali facility.

The release of mercury to the environment is of particular concern because of its volatility, persistence, and tendency to bioaccumulate. The recovery of mercury from end-box exhaust at chlor-alkali facilities is important to prevent release into the environment and reduce emissions as required by NESHAP (National Emission Standards for Hazardous Air Pollutants). A pilot-scale photocatalytic reactor packed with silica-titania composite (STC) pellets was tested at a chloralkali facility over a 3-month period. This pilot reactor treated up to 10 ft3/min (ACFM) of end-box exhaust and achieved 95% removal. The pilot reactor was able to maintain excellent removal efficiency even with large fluctuations in influent mercury concentration (400-1600 microg/ft3). The STC pellets were regenerated ex situ by regeneration with hydrochloric acid and performed similarly to virgin STC pellets when returned to service. On the basis of these promising results, two full-scale reactors with in situ regeneration capabilities were installed and operated. After optimization, these reactors performed similarly to the pilot reactor. A cost analysis was performed comparing the treatment costs (i.e., cost per pound of mercury removed) for sulfur-impregnated activated carbon and the STC system. The STC proved to be both technologically and economically feasible for this installation.

Development of cost-effective noncarbon sorbents for Hg(0) removal from coal-fired power plants.

Noncarbonaceous materials or mineral oxides (silica gel, alumina, molecular sieves, zeolites, and montmorillonite) were modified with various functional groups such as amine, amide, thiol, urea, and active additives such as elemental sulfur, sodium sulfide, and sodium polysulfide to examine their potential as sorbents for the removal of elemental mercury (Hg(0)) vapor at coal-fired utility power plants. A number of sorbent candidates such as amine- silica gel, urea- silica gel, thiol- silica gel, amide-silica gel, sulfur-alumina, sulfur-molecular sieve, sulfur-montmorillonite, sodium sulfide-montmorillonite, and sodium polysulfide-montmorillonite, were synthesized and tested in a lab-scale fixed-bed system under an argon flow for screening purposes at 70 degrees C and/or 140 degrees C. Several functionalized silica materials reported in previous studies to effectively control heavy metals in the aqueous phase showed insignificant adsorption capacities for Hg(0) control in the gas phase, suggesting that mercury removal mechanisms in both phases are different. Among elemental sulfur-, sodium sulfide-, and sodium polysulfide-impregnated inorganic samples, sodium polysulfide-impregnated montmorillonite K 10 showed a moderate adsorption capacity at 70 degrees C, which can be used for sorbent injection prior to the wet FGD system.

On-site mercury-contaminated soils remediation by using thermal desorption technology.

In this study, the thermal desorption process was used to treat a mercury-contaminated soils in Taipei. A series of bench or pilot plant experiments were also performed the optimized operation condition. The results showed that the concentrations of residual mercury in all treated soils were below 2 mg/kg, some even lower than 0.05 mg/kg. The supernatant and exhaust gas stream of the condensed desorbed mercury vapor in the remediation site were also met with the effluent standard. The total fee was estimated to be US 3,557,000 dollars, when treating contaminated soil leading to a unit treatment cost of US 834 dollars/m3 of soil.

Capture of mercury ions by natural and industrial materials.

In this paper the technical feasibility of various adsorbents for mercury removal from contaminated waters has been studied. Adsorption isotherms of mercury ions in aqueous solution have been experimentally measured on a granular activated carbon (Aquacarb 207EA), a char, a pozzolana and a yellow tuff. The experimental evidences show that the mercury capture capacity of yellow tuff and char is of few tenths of milligrams per gram of sorbent while for the pozzolana and the activated carbon this value is of the order of 1mg/g of sorbent. Moreover, for a mercury concentration as high as 3000 microg/l the pozzolana shows the highest adsorption capacity. This result seems to be quite interesting, especially in consideration of the extremely low cost of this natural sorbent.

Using Wet-FGD systems for mercury removal.

A plan to control mercury emissions to the atmosphere and to establish mercury emission limits has recently been elaborated by the European Commission, making it necessary to devise an efficient and cost effective mercury removal technology. Towards this end wet flue gas desulfurization units appear as a promising option for multi-pollutant control. However, more investigation on mercury removal and a greater mercury removal efficiency are required to achieve this objective. In the present work scrubber chemistry and the application of various solid additives to enhance mercury removal in wet scrubbers is evaluated. The results obtained show a significant correlation between mercury removal efficiency and the pH of the scrubber slurry and SO2 concentration. A weaker correlation was observed between oxygen or slurry concentration and removal efficiency. Finally several solid oxides were found to be effective additives for enhancing mercury capture in wet scrubbers.

Microbial removal of ionic mercury in a three-phase fluidized bed reactor.

The reductive biotransformation of mercuric ions to elemental mercury was studied by applying a model system with a genetically engineered Pseudomonas putida strain in a lab scale three-phase fluidized bed (TPFB). The aim was to demonstrate the suitability of the TPFB to demercurize effluent streams containing up to 10 mg Hg2+ dm(-3). The TPFB is used, first, to carry out the biotransformation on the alginate immobilized biocatalyst and, second, to remove the produced Hg0 by volatilization into the gas phase followed by its recovery through fast oxidative absorption. Targeted experiments with the immobilized biocatalyst were designed and carried out to determine mercury adsorption data on the biomass and all relevant mass transport rates at conditions prevailing in the TPFB. The evaluation of the performance data in the TPFB revealed almost complete reaction control and hence negligibility of mass transfer resistances. This simplifies the scale-up of larger TPFB reactors for mercury removal as it can be based on the known kinetics alone. The measured biotransformation capacities in the TPFB are similar to those reported for the fixed bed technology which has already proven its applicability at an industrial scale in long time runs. However, the TPFB offers some advantages over the fixed bed and could therefore possibly be a favorable, reliable, and less costly alternative to the existing technology.

A pilot scale evaluation of removal of mercury from pharmaceutical wastewater using granular activated carbon.

Thimerosal (an organic mercury compound) is widely used in the pharmaceutical industry and hospitals. This study examines the removal of mercury (thimerosal and Hg(II)) from a pharmaceutical wastewater using F-400 granular activated carbon (GAC) at bench and pilot scales. Bench scale dynamic column tests are conducted with 30, 60, 90 and 120 min empty bed contact times (EBCTs). The pilot scale study is conducted using two GAC columns-in-series each of 30 min EBCT. The capital and operational cost analysis for the treatment system is performed. Simultaneous removal of copper, turbidity, phenol, and color from the wastewater by the pilot scale system is also reported.

Reduction of mercury, copper, nickel, cadmium, and zinc levels in solution by competitive adsorption onto peanut hulls, and raw and aged bark.

The competitive adsorption of common heavy metal ions by peanut hulls, raw bark, and composted bark was studied. These solid wastes were found to adsorb significant amounts of one or more of the heavy metals (Hg, Cu, Ni, Cd, Zn) commonly found in municipal sludge and wastewater.