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A novel electrochemical sensor was developed for sensitive and selective detection of mercury(II), based on thymine--[Hg.sup.2+]--thymine (T--[Hg.sup.2+]--T) coordination chemistry. This strategy exploited the cooperativity of proximate poly-T oligonucleotides in coordination with [Hg.sup.2+]. Ferrocene (Fc)-tagged poly-T oligonucleotides were immobilized on the electrode surface via self-assembly of the terminal thiol moiety. In the presence of [Hg.sup.2+], a pair of poly-T oligonucleotides could cooperatively coordinate with [Hg.sup.2+], which triggered a conformational reorganization of the poly-T oligonucleotides from flexible single strands to relatively rigid duplexlike complexes, thus drawing the Fc tags away from the electrode with a substantially decreased redox current. The response characteristics of the sensor were thoroughly investigated using capillary electrophoresis and electrochemical measurements. The results revealed that the sensor showed a sensitive response to [Hg.sup.2+] in a concentration range from 1.0 nM to 2.0 [micro]M, with a detection limit of 0.5 nM. Also, this strategy afforded exquisite selectivity for [Hg.sup.2+] against a reservoir of other environmentally related metal ions, compared to existing anodic stripping voltammetry (ASV) techniques. In addition, this sensor could be implemented using minimal reagents and working steps with excellent reusability through mild regeneration procedure. It was expected that this cost-effective electrochemical sensor might hold considerable potential in on-site applications of [Hg.sup.2+] detection.

Single-strand DNA (ssDNA) was used to modify 10 nm nanogold to obtain an aptamer-modified nanogold resonance scattering (RS) probe (AussDNA) for detection of [Hg.sup.2+]. In the presence of NaCl, [Hg.sup.2+] interacts with d to form very stable double-strand T--[Hg.sup.2+]--T mismatches and release nanogold particles that aggregate to large nanogold clusters causing the RS intensity at 540 nm to be enhanced linearly. On those grounds, 1.3-1667 nM [Hg.sup.2+] can be detected rapidly by the aptamer-modified nanogold RS assay, with a detection limit of 0.7 nM [Hg.sup.2+]. If the large nanogold clusters were removed by membrane filtration, the excess AussDNA in the filtrate solution exhibits a catalytic effect on the new [Cu.sub.2]O particle reaction between N[H.sub.2]OH and [Cu.sup.2+]--EDTA complex at 60[degrees]C. The excess AussDNA decreased with the addition of [Hg.sup.2+], which led the [Cu.sub.2]O particle RS intensity at 602 nm to decrease. The decreased RS intensity ([DELTA][I.sub.602nm]) had a linear response to [Hg.sup.2+] concentration in the range of 0.1-400 nM, with a detection limit of 0.03 nM [Hg.sup.2+]. This aptamer-modified nanogoid catalytic RS method was applied for the detection of [Hg.sup.2+] in water samples, with sensitivity, selectivity, and simplicity.

Elevated Hg concentrations in the Everglades pose ecological and human health risks. We mapped soil total Hg concentrations per mass ([THg.sub.M]) and area ([THg.sub.A]) across the Everglades, and investigated relationships with soil properties (total P [TP] and organic matter content), community type, and hydrologic compartmentalization. Samples (n = 600) from surface soils (0-10 cm) were selected from a population of 1405 sites spanning the Everglades. Overall, 168 sites had [THg.sub.M] levels >0.2 mg [kg.sup.-1]; interpolation suggests that 23% of the Greater Everglades exceeds this threshold. Hot spots (>0.4 mg [kg.sup.-1]) were observed in eastern Water Conservation Area (WCA) 1 and west-central WCA3A; parts of WCA2A, WCA3AN, and WCA3B were locally high. Despite significant global differences in [THg.sub.M] among plant communities, differences evaluated using paired proximate sites were not significant, suggesting that large spatial scale depositional gradients govern ecosystem storage. Median [THg.sub.A] was 1.89 mg [m.sup.-2] (range 0.07-12.05 mg [m.sup.-2]), representing approximately 100 yr of atmospheric deposition at contemporary rates (~19 [micro]g [m.sup.-2] [yr.sup.-l]). Correlation between TP and [THg.sub.M] was positive in unimpacted areas (TP < 500 mg [kg.sup.-1], r = 0.69), but negative in impacted areas (TP > 500 mg [kg.sup.-1], r = -0.47), probably due to accelerated peat accretion rates in P-enriched areas. Moreover, while reverse correlation with distance from a canal for [THg.sub.M] (0.70) and TP (-0.77) supports Hg enrichment via atmospheric deposition, [THg.sub.M] hotspots in WCA3AS, WCA1, and the Holeyland and Rotenberger tracts are suggestive of local enrichment mechanisms. Finally, despite dramatic regional emissions declines, the estimated mass of Hg in surface soils across the Everglades has increased ~20% (11,000 vs. 13,100 kg) since 1996; while the statistical significance of this change is unknown, it provides a useful benchmark for future surveys. Abbreviations: BCNE Big Cypress National Preserve; BD, bulk density; EAA, Everglades Agricultural Area; ENP, Everglades National Park; HLRB, Holeyland and Rotenberger tracts; LOI, loss-on-ignition; MeHg, methyl-mercury; OK, ordinary kriging; THg, total mercury; [THg.sub.A], total mercury per area; [THg.sub.M], total mercury per mass; TP, total phosphorus; WCA, water conservation area.

This paper describes a project that assessed the potential for mercury (Hg) release to air and water from soil amended with combustion products to simulate beneficial use. Combustion products (ash) derived from wood, sewage sludge, subbituminous coal, and a subbituminous coal-petroleum coke mixture were added to soil as agricultural supplements, soil stabilizers, and to develop low-permeability surfaces. Hg release was measured from the latter when intact and after it was broken up and mixed into the soil. Air-substrate Hg exchange was measured for all materials six times over 24 hr, providing data that reflected winter, spring, summer, and fall meteorological conditions. Dry deposition of atmospheric Hg and emission of Hg to the atmosphere were both found to be important fluxes. Measured differences in seasonal and diel (24 hr) fluxes demonstrated that to establish an annual estimate of air-substrate flux from these materials data on both of these time steps should be collected. Air-substrate exchange was highly correlated with soil and air temperature, as well as incident light. Hg releases to the atmosphere from coal and wood combustion product-amended soils to simulate an agricultural application were similar to that measured for the unamended soil, whereas releases to the air for the sludge-amended materials were higher. Hg released to soil solutions during the Synthetic Precipitation Leaching Procedure for ash-amended materials was higher than that released from soil alone. On the basis of estimates of annual releases of Hg to the air from the materials used, emissions from coal and wood ash-amended soil to simulate an agricultural application could simply be re-emission of Hg deposited by wet processes from the atmosphere; however, releases from sludge-amended materials and those generated to simulate soil stabilization and disturbed low-permeability pads include Hg indigenous to the material., INTRODUCTION Solid products left as residues after combustion of coal, wood, and sewage sludge are either placed in landfills or put to some beneficial use. Of the approximately 123 million [...]

Five field trips were conducted in the San Francisco Bay-Delta between May 2000 and October 2001 to investigate the sediment-water exchange of total mercury (Hg) and monomethyl mercury (MMHg). Solid-phase Hg averaged ~1 nmol [g.sup.-1] and did not show any variability with depth or time or among sites. In contrast, solid-phase MMHg showed considerable vertical, temporal, and spatial variability (0.4-66 pmol [g.sup.-1]), with the highest values occurring at a peat-rich environment in May 2001, suggesting that MMHg production was largely controlled by temporal factors and habitat type. In pore water, both Hg and MMHg concentrations were generally elevated near the sediment-water interface during warm months. Sediment-water exchange flux of MMHg, determined with benthic chamber deployments, ranged from -92 to 850 pmol [m.sup.-2] [d.sup.-1], with higher values occurring in May. In most cases, diffusional fluxes of Hg and MMHg, estimated with the use of interfacial concentration gradients, constituted only a minor portion of the measured fluxes, suggesting the importance of advective processes on sediment-water exchange. Surface-water transect and time series studies conducted in Franks Tract support the commonly held belief that wetland and marsh regions are major sources for MMHg within the Delta. The integrated sediment-water fluxes of Hg and MMHg in the study area were estimated to be 130 and 6 mmol [d.sup.-1], respectively, and the benthic input was as important a source of Hg and MMHg as the riverine input within the Delta during low-flow months.

Sorption by soil colloids largely determines the bioavailability of heavy metals and their movement in soil and aquatic environments. Due to soil constituents' interactions, the sorption behavior of natural soil colloids may not correspond to the simple sum of their individual constituents. In this work, sorption of Pb(II) and Hg(II) ions by binary and ternary model particles containing Wyoming montmorillonite (SW), poorly crystallized ferrihydrite (Ferrih), and soil humic acid (HA) was investigated and the results obtained were compared with the sorption behavior of the individual constituents. For single sorbents, Pb(II) sorption was high on HA, moderate on SW and zero on Ferrih, whereas Hg(II) sorption decreased in the order: HA >> Ferrih > SW. Ferrihydrite coatings on SW had little effect on Pb(II) and Hg(II) sorption by the clay. Humic acid coatings on SW significantly enhanced sorption of both heavy metals, whereas, unexpectedly, HA coatings on Ferrih did not enhance heavy metal sorption. This last result was attributed to blockage of the functional groups of HA responsible for heavy metal sorption (such as carboxylic groups} as a result of their interaction with the Ferrih surface. A similar behavior was observed for Pb(II) in ternary particles containing HA. Sorption by the model associations was highly reversible. The results of this study confirmed that the sorptive behavior of colloidal particles for heavy metals is not the simple sum of the contributions of the single constituents, indicating the usefulness of considering polyphasic model sorbents to achieve a more realistic interpretation of the sorption process in soil.

This paper reports on the use of solid sampling-electro. thermal vaporization-inductively coupled plasma mass spectrometry (SS-ETV-ICPMS) for the direct and simultaneous determination of methylmercury and inorganic mercury in biological materials. The main advantage of this fast and sensitive method is that no sample preparation is required. In this way, the sample throughput can be considerably increased, problems of contamination and analyte losses are kept to a minimum and, even more important, the original chemical form of the different analyte species in the solid samples is preserved. To achieve this goal, a solid sample is inserted into a graphite furnace of the boat-in-tube type and is subsequently submitted to an appropriate temperature program, leading to the separate vaporization of methylmercury and inorganic mercury, which are transported into the ICP by means of an argon carrier gas. The separation was accomplished within 75 s. For the quantification of the two peaks, species-unspecific isotope dilution was used. For this purpose, a stable flow of argon loaded with gaseous Hg isotopically enriched in [sup.200]Hg was generated using a permeation tube that was constructed in-house. Its emission rate was determined by collecting the mercury released during a given time interval on a gold-coated silica absorber, after which the amount collected was released by heating of the absorber and determined by cold vapor atomic absorption spectrometry (CVAAS) and cold vapor atomic fluorescence spectrometry (CVAFS). A reference material from the Canadian National Research Council (NRC) (TORT-2) was used to assess the accuracy of the method. For the application of the method to samples with diverse mercury contents, the spike/sample ratio can be optimized by varying the emission rate of the permeation tube simply by adapting its temperature. To prove the feasibility of this approach, two reference materials (BCR 463 and DORM-2) with a methylmercury content more than 10 times higher than that of TORT-2 were also analyzed. The detection limits obtained for 1 mg of sample (2 ng [g.sup.-1] and 6 ng [g.sup.-1] for methylmercury and inorganic mercury, respectively) were found to be sufficiently low for this kind of application and are competitive when compared to other techniques.

An automatic microgravimetric screening system based on piezoelectric detection and the use of acidic stannous chloride as reductant was developed for the fast detection and determination of total mercury in water. Reduced mercury is detected as an amalgam by using a gold-coated piezoelectric crystal, the sensor subsequently being regenerated by passing it through a peroxydisulfate solution. The gold-coated piezoelectric crystal is a highly efficient retention unit for the main soluble mercury species (inorganic, complexed, and organometallic) previously reduced to elemental mercury and is free of interferences from other metal ions. This detector exhibits good sensitivity: it allows the determination of mercury at sub-parts-per-billion concentration levels (0.30-1.00 [micro]g/L). The precision, expressed as relative standard deviation, was [+ or -] 2.7% (n = 11; P = 0.05) at 0.5 [micro]g/L total mercury. The proposed method was successfully used as a rapid screening method for mercury monitoring in natural waters.

A compact device based on purge-and-trap multicapillary gas chromatography was developed for sensitive species-selective analysis of methylmercury and [Hg.sup.2+] by atomic spectrometry. The operating mode includes in situ conversion of the analyte species to MeEtHg and Hg[Et.sub.2] and cryotrapping of the derivatives formed in a 0.53-mm-i.d. capillary, followed by their flash (60 mL [min.sup.-1]) compatible with an MIP AES detector (no dilution with a makeup gas is required). Developments regarding each of the steps of the analytical procedure and effects of operational variables (sample volume, purge flow, trap temperature, separation conditions) are discussed. The device allows speciation of Me[Hg.sup.+] and [Hg.sup.2+] down to 5 pg [g.sup.-1] in urine and, after a rapid microwave-assisted hydrolysis, down to 0.1 ng [g.sup.-1] in solid biological samples with a throughput of 6 samples/h. The analytical protocols developed were validated by the analysis of DORM- 1 (dogfish muscle), TORT-1 (lobster hepatopancreas), and Seronorm urine certified reference materials.

Water-soluble compounds of mercury present in flue gases, also called reactive gaseous mercury (RGM), exhibit seasonal characteristics comparable to other regional air pollutants. The seasonal characteristics of RGM are attributed to its high correlation with temperature, ozone, sulfur dioxide and total gaseous mercury. Analysis shows that RGM's concentrations tend to be higher during midday and lower during nightime. Episodes of rain also lessen the concentration of RGM in ambient air.

Byline: Janos Vetter (1), Erzsebet Berta (1) Keywords: Key wordsaMercury; Wild edible mushrooms; Atomic absorption spectrometry; Agaricus; Macrolepiota; Lepista; Lycoperdon perlatum Abstract: aThe mercury (Hg) content of 112 samples of common, wild edible mushrooms was analysed by atomic absorption spectrometry. The average Hg content of all the samples was 1.72 mg/kg dry mass (DM) but the Hg concentrations found in different taxonomic groups (genera and species varied) remarkably. Although different sampling locations obviously have an effect on the Hg concentration of sporocarps, we found evidence for a Hg-accumulating capacity of some taxonomic groups. In addition to Agaricus and Macrolepiota, where the phenomenon of mercury accumulation has already been described, our results indicate high Hg levels in samples of Lycoperdon perlatum (average 2.94 mg/kg DM) and in Lepista species (average 3.02 mg/kg DM). These data confirm the need for greater attention to be given to Hg levels in wild common mushrooms, especially to Hg-accumulating species. Author Affiliation: (1) Department of Botany and Biological Laboratory, University of Veterinary Science, P.O. Box 2, H-1400 Budapest, Hungary, HU Article note: Received: 20 February 1997

Sediment core samples were used to assess atmospheric mercury deposition in the Upper Midwest. Core samples from study lakes in eastern and western Minnesota, Minneapolis and southeastern Alaska showed a decreasing pattern of atmospheric mercury deposition in the Upper Midwest while global mercury deposition, represented by samples from Alaska, showed increases in deposition. The regional discrepancy is explained by the shift to cleaner fuels by the energy industry, long distance transport of pollutants and decrease in waste incineration.

A novel method employed for determining trace mercury in water and biological samples was developed in the study. The mercury was preconcentrated from the water samples and the digested biological samples through means of diethyldithiocarbamate extraction in conjunction with [Au.sup.3+] back extraction. The preconcentrated solution, which simply contained the enriched mercury ion with the possible transition-metal ions and nonreacted [Au.sup.3+], was next transferred to an electrochemical cell for detecting mercury via differential pulse anodic stripping voltammetry (DPASV) through the usage of a gold film carbon electrode. [Au.sup.3+] was selected as a back-extracting agent in light of its standing as highest extraction constant with diethyldithiocarbamate, being greater than that of [Hg.sup.2+]. Besides, the excess nonreacted [Au.sup.3+] in the preconcentrated solution could be used in situ as the source of generating the gold film of the working electrode in the DPASV. Sufficient evidence of high feasibility in the determination of mercury for different water samples was provided in this present work. Reliability and accuracy of this novel method were confirmed from the NBS biological standard reference materials analysis.

A new technique for the measurement of mercury density in high intensity arc discharge (HID) lamps was presented. The method used x-ray absorption spectra and was applicable for lamps with any outer envelopes. The technique was able to measure the absolute densities and cold spot temperatures of several types of HID lamps during the period subsequent to arc extinguishment. Time dependent mercury mass per unit area measurements were obtained during the warming up process.

Byline: Neetu Bansal A highly selective and sensitive, spectrophotometric method is developed for the determination of Mercury(II) in environmental waters samples, based on indicator reaction of potassium hexacyanoferrate(II) and 2-methylpyrazine (2-Mepz), catalysed by Hg(II). The reaction was monitored spectrophotometrically at pH = 3.50 [+ or -] 0.02 and 25.0 [+ or -] 0.1[degrees]C by measuring the change in absorbance over time at 447 nm (λmax = 447 nm) for 20 min. Mercury can be determined within the range 20.06-200.6 ng mL−1 with relative standard deviation of sr = 3.02 at 20.06 ng/mL Hg(II) level. Interference due to many cations and anions was also studied at 200.6 ng/mL level.

The hydrologic cycling of total Hg (HgT) and organic C (OC) was studied for a 1-yr period in a northern Minnesota forested watershed, consisting of an upland surrounding a bog peatland with a narrow lagg at their interface. Throughfall and stemflow contributed twice as much HgT and seven times as much OC to the forested watershed than atmospheric deposition in a nearby opening. Fluxes in upland runoff accounted for 16% of the HgT and 8% of the OC inputs to the lagg and were dominated by interflow transport. Bog runoff accounted for 57% of the HgT and 83% of the OC inputs to the lagg. For an annual cycle, upland soils were sinks for both HgT and OC, while bog soils were sinks for HgT but sources of OC. Fluxes to the lagg accounted for 184% of the HgT and 87% of the OC transported from the watershed outlet. We speculate that HgT was lost in the lagg by both volatilization and soil accumulation. Total Hg and dissolved organic C (DOC) are positively related in both throughfall and stemflow, with stemflow showing the strongest relationships. In the soil system, HgT--DOC relationships deteriorate and HgT--particulate organic C (POC) relationships dominate. Water residence time in contact with OC appears to be important in determining the relationships between HgT and OC. At the stream outlet, our data suggest that [approximately equals] 70% of the HgT transported from the watershed is associated with POC, while 30% is associated with DOC.

Woods et al. (2007) reported on exposure to dental amalgam fillings and urinary mercury excretion in children. They stated that "urinary mercury concentrations are widely used as a measure of [...]

Most attention to HFCS lately, whether in the news or in the scientific literature, has been around its potential contribution to obesity and other diet-related disease. Increased consumption of calories [...]