Loss Of Mercury Research Articles

Sampling and Analysis of Mercury in Crude Oil

Abstract Sampling and analytical procedures used to determine total mercury content in crude oils were examined. Three analytical methods were compared with respect to accuracy, precision, and detection limit. The combustion method (U.S. EPA 7473 hybrid) and a commercial extraction method (non-standard) were found adequate to provide a good combination of sensitivity and accuracy, while instrumental neutron activation analysis was found to suffer from interferences from elements other than mercury (Ni, Se) that are typically found in crude oil. Aliquot removal and processing steps were found to be important to accuracy and precision of the combustion method. Potential errors caused by incomplete homogenization and loss of volatile mercury were investigated in detail. Homogenization of oils that contain suspended mercury compounds was found important to allow retrieval of representative aliquots for analysis. Ultrasonication at slightly elevated temperature yielded the more reproducible and higher magnitude results. It was discovered that volatile mercury can be lost from sample containers when they are opened to remove aliquots. Alternative sample containers and aliquot removal techniques were developed that minimized loss of volatile mercury. Speciation experiments were utilized to determine the identity of volatile species and the rates at which they are lost from containers. Both elemental mercury and dimethylmercury were identified as volatile mercury components of one freshly sampled crude oil.

Mercury loss from soils following conversion from forest to pasture in Rondônia, Western Amazon, Brazil

This work reports on the effect of land use change on Hg distribution in Amazon soils. It provides a comparison among Hg concentrations and distribution along soil profiles under different land use categories; primary tropical forest, slashed forest prior to burning, a 1-year silviculture plot planted after 4 years of forest removal and a 5-year-old pasture plot. Mercury concentrations were highest in deeper (60–80cm) layers in all four plots. Forest soils showed the highest Hg concentrations, ranging from 128ngg−1 at the soil surface to 150ngg−1 at 60–80cm of depth. Lower concentrations were found in pasture soils, ranging from 69ngg−1 at the topsoil to 135ngg−1 at 60–80cm of depth. Slashed and silviculture soils showed intermediate concentrations. Differences among plots of different soil-use categories decreased with soil depth, being non-significant below 60cm of depth. Mercury burdens were only statistically significantly different between pasture and forest soils at the topsoil, due to the large variability of concentrations. Consequently, estimated Hg losses were only significant between these two land use categories, and only for the surface layers. Estimated Hg loss due to forest conversion to pasture ranged from 8.5mgm−2 to 18.5mgm−2, for the first 20cm of the soil profile. Mercury loss was comparable to loss rates estimated for other Amazon sites and seems to be directly related to Hg concentrations present in soils.

Mercury accumulation and loss in mallard eggs.

Female mallards (Anas platyrhynchos) were fed diets containing 5, 10, or 20 ppm mercury as methylmercury chloride. One egg was collected from each bird before the start of the mercury diets and 15 eggs were collected from each bird while it was being fed mercury. The mercury diets were then replaced by uncontaminated diets, and each female was allowed to lay 29 more eggs. Mercury levels in eggs rose to about 7, 18, and 35 ppm wet-weight in females fed 5, 10, or 20 ppm mercury, respectively. Mercury levels fell to about 0.16, 0.80, and 1.7 ppm in the last egg laid by birds that had earlier been fed 5, 10, or 20 ppm mercury, respectively. Higher concentrations of mercury were found in egg albumen than in yolk, and between 95 and 100% of the mercury in the eggs was in the form of methylmercury.

Concentrations of hazardous heavy metals in environmental samples collected in Xiamen, China, as determined by vapor generation non-dispersive atomic fluorescence spectrometry.

Non-dispersive atomic fluorescence spectrometry (NDAFS) coupled with vapor generation (VG) sample introduction was applied to the determination of the concentrations of hazardous heavy metals, such as arsenic, cadmium, lead and mercury, in seawater, soils and total airborne particulate matter (PM) collected around the Xiamen area in China. Almost 100% sample introduction efficiency was achieved by using thiourea and ascorbic acid for the pre-reduction of As(V) to As(III), K3Fe(CN)6 and tartaric acid for pre-oxidation of Pb(II) to Pb(IV), and masking the interferences arising from the co-existing transition metals to As, Cd, Hg and Pb during their vapor generation process. Moreover, a novel sample pretreatment device was developed to avoid the loss of mercury, lead, cadmium and arsenic during sample pretreatment. With such methods, the detection limit (DL) of arsenic, cadmium, lead and mercury was down to 0.08, 0.03, 0.05, 0.01 ng mL(-1) (3sigma), respectively. The relative standard deviations (RSD, n = 11) for arsenic, cadmium, lead and mercury at 10 ng mL(-1) were 0.9%, 1.6%, 1.3% and 2.0%, respectively. The concentrations of hazardous heavy metals in the environmental samples collected in Xiamen, China are in the range from 0.02 +/- 0.001 ng mL(-1) in seawater to 15.3 +/- 0.2 microg g(-1) in soils. Besides flame/GF-AAS and ICP-AES/MS, VG-NDAFS should be another choice for the determination of hazardous heavy metals in environmental samples.

Reduction of Mercury Loss in Fluorescent Lamps Coated with Thin Metal-Oxide Films

The absorption of mercury into glass and metal-oxide coated glass tubes is investigated with the aid of Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), low-energy ion scattering, and thermal desorption mass spectroscopy. The absorption reaction of bare glass with activated mercury species is strongly reduced when the glass is covered with a thin oxide film. The concentration profile of the mercury measured in the films with the aid of RBS varied between a homogeneous distribution and a higher concentration of mercury close to the discharge side of the coating. XPS showed that the oxidation state of the mercury at the surface of the coatings was between that of metallic mercury and mercury(II) oxide. Thermal desorption mass spectroscopy showed that at least two different states of bound mercury were involved. The combination of the thermal desorption mass spectroscopy and XPS led to the conclusion that direct mercury-metal-oxide interactions contribute to the bonding of the mercury. © 2003 The Electrochemical Society. All rights reserved.

Mercury accumulation and loss by necrophageous calliphoridae larvae (diptera)

Fish represent the dominant methylmercury (CH 3 Hg) pool in aquatic systems and CH 3 Hg released from carcasses after fish death could constitute a significant flux to the environment. Necrophageous invertebrates play an important role in this Hg recycling. Necrophageous calliphorid fly larvae (Diptera) are known to consume beached carcasses. In this study, we report that the Hg these flies accumulate from fish carcasses is retained in their pupal stage but is eliminated by the adult following emergence. Thus calliphorids possess an efficient mechanism for excreting the Hg that they accumulate from carcasses.

Stability of mercury-coated platinum microelectrodes upon touching a solid surface in scanning electrochemical microscopy (SECM) experiments

The features of experimental approach curves, recorded in scanning electrochemical microscopy measurements, and acquired with a series of sphere-cap tips while approaching a solid insulating substrate, are examined in detail. Sphere-caps are prepared by electrodeposition of liquid mercury onto a platinum microdisk substrate 10 μm radius, and having RG= R/ a=10 ( R is total tip dimension, which includes the shield thickness and the electrode radius a). From the data obtained, it is established that sphere caps with aspect ratio h/ a>0.3 ( h is the sphere cap height) are able to touch, or even be squeezed against the surface of the solid substrate. Under these latter conditions, for the sphere caps, the negative feedback process at low tip–substrate distances, is more pronounced than that of the corresponding naked microdisk. A good tip stability and no mercury loss is observed upon touching the substrate for sphere caps with h/ a<1.3. This circumstance allows one to perform “contact” voltammetric measurements of lead ions adsorbed onto a thin layer chromatography plate.

Transmission electron microscopic study of early stage γ 1 (Ag 2Hg 3) and β 1 (Ag-Hg) phases : Technical note

Incomplete reaction, residual free mercury, and high volatility of mercury are often major causes of the discrepancy in chemical composition of γ 1 measured by different methods. The high mercury volatility also proves to be a major difficulty in transmission electron microscopy (TEM) study of high mercury materials. Provided in this report is a preparation method for TEM thin foils that can largely eliminate the mercury loss problem. The results show that the lattice constant of early stage γ 1 crystals is 10.05 Δ with a chemical composition of Ag 41.08Hg 58.92 (or Ag 2Hg 2.87). The chemical composition data shows that little or no mercury is lost during specimen preparation. The lattice parameters, a and c, of β 1 crystals are 3.01 and 4.88 Δ, respectively with a chemical composition of Ag 1.1Hg 0.94. It seems that the present specimen preparation method allows for accurate TEM microanalysis of high mercury amalgam phases such as γ 1 and β 1, which has been extremely difficult to do in the past.

Flue gas Hg measurements from coal-fired boilers equipped with wet scrubbers

The U.S. EPA has indicated they are considering additional SO2 and NOx emission reductions, and EPA is under a consent agreement to propose mercury reduction regulations by 2004 for the utility industry. The boiler manufacturers and the utility industry have developed improved combustion modification techniques to reduce NOx emissions. These advanced combustion modification techniques, plus selective catalytic reduction (SCR), offer the potential to reduce NOx emissions at reduced cost. Wet and dry FGD systems have been shown to reduce SO2 emissions by up to 95%. CONSOL has shown that conventional wet FGD and ESP systems can remove an average of 67±6% of the inlet mercury. These data show that utility boilers equipped with ESP-scrubber combinations are removing two-thirds of the mercury in the as-fired coal at no added cost. The mercury speciation data show that 80 to 95% of the oxidised mercury, as determined by the Ontario Hydro method, is removed by the scrubber. The average mercury material balance closure at the six plants was 103±8%. The mercury removed from the scrubber reported to the scrubber by-product. Standard leachate testing conducted on fixated and unfixated scrubber by-product from one test showed no mercury leaching. Mercury volatility was evaluated by heating the scrubber by-product 140°F for eleven weeks. After eleven weeks, no loss of mercury was reported. Based on these findings, there may be combinations of environmental control systems that can achieve significant SO2, NOx, and mercury reductions at lower cost than the conventional approach of three add-on processes FGD for SO2 control, selective catalytic reduction for NOx control, and carbon injection for mercury control.

History of mercury migration from Minamata Bay to the Yatsushiro Sea

Mercury concentrations were measured in sediment cores collected from the Yatsushiro Sea to clarify physical transport of mercury from Minamata, the site of major methylmercury pollution in Japan, to the surrounding sea. The results suggested that the mercury pollution in the Yatsushiro Sea sediment was caused by a slow migration of mercury-bearing sediment particles from Minamata Bay. The deposition rate of mercury observed at the Yatsushiro Sea was correlated with cumulative loss of mercury from an acetaldehyde facility in Chisso Minamata, with a certain time-lag.

Sono-Adsorptive Stripping Voltammetry: Its Application to the Analysis of Metals and Organic Compounds in Aqueous Media

The effect of applying ultrasound during the preconcentration step of the adsorptive stripping voltammetry (AdSV) analysis of vanadium, nickel and riboflavin is presented. First, the sono-AdSV determination of vanadium(V) was achieved by interfacial accumulation of its catechol complex under ultrasound applied from an ultrasonic probe opposite a mercury-coated copper electrode. Ultrasound was found to increase the speed at which the complex was deposited onto the mercury surface in comparison with silent conditions. Similar analytical performances to those described in the literature were obtained for shorter preconcentration times under ultrasound. Second, the effect of ultrasound on the AdSV analysis of Ni2+ was studied using a mercury film plated in situ on a glassy carbon electrode. Dimethylglyoxime was used as the complexing agent. The loss of mercury due to sonication is shown to decrease the sensitivity of the method. Third, the sono-AdSV analysis of an organic compound, riboflavin, was investigated. Accumulation of riboflavin was conducted both in a preplated mercury film electrode and on a glassy carbon substrate. Faster rates of adsorption were observed for riboflavin under the presence of ultrasound. In addition the AdSV analysis of riboflavin also benefits from surface activation of the glassy carbon electrode due to cleaning of its surface by the use of ultrasound. In this respect, partial removal of lumichrome, a less adsorbing species than riboflavin under these conditions and a product of riboflavin photolysis, has been observed under sonication.

Discharge residue from mercury fulminate-primed ammunition

The scarcity of mercury in discharge residue particles from mercury-containing ammunition was investigated. It was found that 86% of the mercury was vaporized after discharge, mainly via the muzzle, 88% of which was not detectable by SEM. Of the 0.16% exiting via the breech, only approximately 40% was detectable by SEM. Only a small proportion of this was deposited on the firer. The recovered mercury did not make a significant contribution to the elemental composition of the discharge residue particles. The rate of loss of mercury from the spent cartridge case was also examined but was found to be of no practical value in estimating time of discharge.

Polyaniline as a base material for preparation of a mercury standard for use in neutron activation analysis

Polyaniline sorbed with microgram quantity of mercury was prepared and its homogeneity and stability with respect to mercury was evaluated over a period of time. The volatilisation loss of mercury during and after neutron irradiation was studied. It was found that polyaniline was homogeneous and stable with respect to mercury. No loss of mercury from polyaniline was observed during and after neutron irradiation. Thus polyaniline sorbed with mercury can serve as a good standard for neutron activation analysis of mercury.

Electrical activation of boron implanted in p-HgCdTe ( x = 0.22) by low-temperature annealing under an anodic oxide

The low-temperature electrical activation of boron atoms implanted in p-HgCdTe has been observed for the first time. The bulk crystals of p-Hg 0.75Cd 0.22Te were implanted at room temperature and at 250 °C with 150 keV B + ions up to a dose of 3 × 10 16 cm −2 through an anodic oxide with a thickness of 90 nm. The same control samples were implanted with N + ions under analogous conditions. The two-step post-implant annealing was carried out at 250 °C for 2–4 h and then at 200 °C up to 44 h in a nitrogen atmosphere. Differential Hall effect measurements at 77 K, optical reflection and secondary ion mass spectroscopy were used for implanted surface layer studies. It was established that the doping efficiency of boron atoms amounts of 0.03–14% decreasing with the increasing boron ion dose and becoming higher in the case of ion implantation at 250 °C. Mercury loss was found not to occur from the surface of HgCdTe through an anodic oxide cap during such heat treatment.

Post-Addition of Sulfuric Acid to Wet Digested Biological and Environmental Materials for Mercury Determination by Cold Vapor Atomic Absorption Spectrometry.

The charring of samples and loss of mercury by a nitric-sulfuric acid mixture has been overcome by prior digestion with nitric acid, followed by the addition of sulfuric acid into the final solution. This approach provides optimum decomposition and analytical conditions for a reliable cold vapor atomic absorption spectrometric determination of mercury in biological and environmental materials. In all cases, the presence of sulfuric acid improved the sensitivity of the mercury response significantly. Furthermore, the prior- and post-addition of sulfuric acid gave similar sensitivity and mercury concentrations for all samples. The adequacy of the prior digestion with nitric acid and post-addition sulfuric acid for reliable mercury determination was successfully demonstrated for blood, bone, bovine liver, mushroom, lake sediment, peat and prawn samples.

Ion acceleration processes in the Hermean and terrestrial magnetospheres

The magnetosphere of Mercury differs in several aspects from that of the other Earth-like planets in our solar system. For instance, the lack of a dense atmosphere and ionosphere implies a different solar-wind magnetosphere interaction compared to that of for example the Earth. However, the solar wind interaction with Mercury might be strongly dependent on a tenuous, but yet significant, exoionosphere. Indeed, the scale sizes and the time constants are different from that of the Earth's magnetosphere, but the large-scale solar wind energy and mass transfer and the intrinsic plasma acceleration processes near Mercury may have very much in common with plasma processes near the Earth. In this report we discuss potential ion acceleration and plasma outflow processes at Mercury in context with results obtained from observations of ion acceleration and outflow in the Earth's magnetosphere and topside ionosphere. We conclude that the acceleration and outflow processes at Mercury, although present in a more extreme environment compared to the other Earth-like planets, are expected to have many similarities with the acceleration and outflow processes near the Earth. Furthermore, we demonstrate that charge-exchange processes in the Hermean magnetosphere are expected to be rather efficient, resulting in “bright flashes” of energetic neutral atom (ENA) generation regions in the nightside atmosphere of Mercury and subsequent loss of magnetospheric plasma. A future mission to Mercury should therefore, besides appropriate plasma experiments, also incorporate ENA imaging experiments.

Determination of Total Mercury in Sediments by Microwave-assisted Digestion-Flow Injection-Inductively Coupled Plasma Mass Spectrometry

A method for the determination of total mercury in sediment samples was developed. Extraction of mercury from a sample matrix was carried out in an open vessel microwave digestion system while maintaining mild conditions during digestion in order to avoid any loss of mercury due to volatilization. A complexing agent (EDTA) and a surfactant (Triton X-100) were added to the samples in order to eliminate memory effects associated with mercury determinations and to obtain reproducible linear calibration curves. Standard additions and internal standardization were used for calibration and correction in an FI–ICP-MS detection system. The method was validated using the certified reference material PACS-1 and the reference materials IAEA-356 and S19 and gave results in good agreement with the certified and reference values. Sediment samples from Arcachon Bay were also analysed. Detection limits of 10 ng g -1 for solution and 1 ng g -1 for dry sediment samples were obtained.

Determination of Total Mercury in Biological Materials by Cold Vapor Atomic Absorption Spectrometry after Microwave Digestion

The use of several acid mixtures for digestion of marine biological materials with microwave-assisted heating was investigated. The mixtures of HNO3–H2SO4–H2O2and of HNO3–H2SO4–HCl were most effective after microwave digestion, resulting in complete decomposition of samples. Recoveries of added mercury to marine biological tissues were satisfactory, ranging from 91 to 108%. This indicated that no matrix interference or loss of volatile mercury occurred during the analysis. The mercury content of standard reference materials after microwave digestion corresponded closely to the certified values.

Production and Loss of Methylmercury and Loss of Total Mercury from Boreal Forest Catchments Containing Different Types of Wetlands

Four terrestrial boreal forest catchments containing different types of wetlands were studied to determine their strength as sources or sinks of methylmercury (MeHg) and total mercury (THg) to downstream ecosystems and to determine if patterns seen in one year were consistent over several years. All catchments were sinks for THg. The wetland type, percentage wetland area (0−25%), or annual water yield did not appear to have a consistent effect on the magnitude of this retention. Wetland areas of the catchments were always net sources of MeHg. Unlike for THg, there were large and consistent differences in the source strength among wetland types for MeHg. These differences appeared to be related to differences in the internal hydrology of the wetlands. All types of wetlands were greater sources of MeHg during years of high water yield, but even during years of low flow all wetland types were sources of MeHg. Thus, we conclude that wetlands are important sites of MeHg production in boreal ecosystems on the l...

Comparison of Acid Mixtures in High-Pressure Microwave Digestion Methods for the Determination of the Total Mercury in Sediments by Cold-Vapor Atomic Absorption Spectrometry

Four closed-vessel microwave digestion methods were compared for the accurate determination of mercury in sediments by flow-injection cold-vapor atomic absorption spectrometry. The results showed that several acid mixtures (HNO3/H2SO4, HNO3/HClO4, HCl/HNO3 and HCl/HNO3/HF) completely digested the soil matrix for the determination of mercury. The method using aqua regia is preferred because it is time saving, less dangerous and suitable for other trace-metal analyses. The merits of pressure-feedback microwave digestion is that it simplifies soil sample digestion, and there is no loss of mercury. The digestion methods were evaluated by determining mercury in NIST SRM 1645 River Sediment, NIES CRM No. 2 Pond Sediment and NRCC BCSS-1 Marine Sediment. Recoveries of 92-108% were achieved. Good recoveries of 94-104% were also obtained for soil and marine-sediment samples spiked with different species of mercury.