Atmospheric mercury measurements carried out in the recent decades have been a subject of bias largely due to insufficient consideration of metrological traceability and associated measurement ...uncertainty, which are ultimately needed for the demonstration of comparability of the measurement results. This is particularly challenging for gaseous Hg
species, which are reactive and their ambient concentrations are very low, causing difficulties in proper sampling and calibration. Calibration for atmospheric Hg
exists, but barriers to reliable calibration are most evident at ambient Hg
concentration levels. We present a calibration of Hg
species based on nonthermal plasma oxidation of Hg
to Hg
. Hg
was produced by quantitative reduction of Hg
in aqueous solution by SnCl
and aeration. The generated Hg
in a stream of He and traces of reaction gas (O
, Cl
, or Br
) was then oxidized to different Hg
species by nonthermal plasma. A highly sensitive
Hg radiotracer was used to evaluate the oxidation efficiency. Nonthermal plasma oxidation efficiencies with corresponding expanded standard uncertainty values were 100.5 ± 4.7% (
= 2) for 100 pg of HgO, 96.8 ± 7.3% (
= 2) for 250 pg of HgCl
, and 77.3 ± 9.4% (
= 2) for 250 pg of HgBr
. The presence of HgO, HgCl
, and HgBr
was confirmed by temperature-programmed desorption quadrupole mass spectrometry (TPD-QMS). This work demonstrates the potential for nonthermal plasma oxidation to generate reliable and repeatable amounts of Hg
compounds for routine calibration of ambient air measurement instrumentation.
Understanding atmospheric mercury chemistry is the key for explaining the biogeochemical cycle of mercury and for improving the predictive capability of computational models. Increased efforts are ...being made to ensure comparable Hg speciation measurements in the air through establishing metrological traceability. While traceability for elemental mercury has been recently set, this is by no means the case for gaseous oxidized mercury (GOM). Since a calibration unit suitable for traceable GOM calibrations based on evaporation of HgCl
solution was recently developed, the purpose of our work was to extensively evaluate its performance. A highly specific and sensitive
Hg radiotracer was used for validation over a wide range of concentrations. By comparing experimental and calculated values, we obtained recoveries for the calibration unit. The average recoveries ranged from 88.5% for 1178 ng m
HgCl
gas concentration to 39.4% for 5.90 ng m
HgCl
gas concentration. The losses were due to the adsorption of oxidized Hg on the inner walls of the calibrator and tubing. An adsorption isotherm was applied to estimate adsorption enthalpy (ΔH
); a ΔH
value of -12.33 kJ mol
was obtained, suggesting exothermal adsorption. The results of the calibrator performance evaluation suggest that a newly developed calibration unit is only suitable for concentrations of HgCl
higher than 1 µg m
. The concentration dependence of recoveries prevents the system from being used for calibration of instruments for ambient GOM measurements. Moreover, the previously assessed uncertainty of this unit at µg m
level (2.0%, k = 2) was re-evaluated by including uncertainty related to recovery and was found to be 4.1%, k = 2. Calibrator performance was also evaluated for HgBr
gas calibration; the recoveries were much lower for HgBr
gas than for HgCl
gas even at a high HgBr
gas concentration (>1 µg m
). As HgBr
is often used as a proxy for various atmospheric HgBr species, the suitability of the unit for such calibration must be further developed.
The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon ...content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg−1. The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 μg kg−1 and n.d. to 17.4 μg kg−1, respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation.
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•The distributions of T-Hg, MeHg, and EtHg near the Idrija Hg mine were investigated.•The Hg values were compared to the chemical composition, TOC, and T-N of the soil.•The first data of EtHg in soil around the mine is reported.•The decomposition of organic matter is closely related to organic Hg formation.•Hg circulation among soil, air and plant with change of chemical forms was suggested.
Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea over the last 15years during several oceanographic cruises on board the Italian research vessels Urania ...and Minerva Uno, covering the Western and Eastern Mediterranean Basins as well as Adriatic Sea as its northernmost part. DGM was measured together with other mercury species (RHg - reactive Hg, THg - total Hg, MeHg - monomethyl Hg and DMeHg - dimethylmercury), and with water quality parameters in coastal and open sea deep water profiles. DGM represents a considerable portion of THg (on average 20%) in Mediterranean waters. Spatial and seasonal variations of measured DGM concentrations were observed in different identified water masses. DGM was the highest in the northern Adriatic, the most polluted part of the Mediterranean Sea as a consequence of Hg mining in Idrija and heavy industry in northern Italy, and near the Gulf of Lion. Generally, average DGM concentration was higher in the West and East Mediterranean Deep Waters (WMDW and EMDW) and Levantine Intermediate Water (LIW) than in overlaying Modified Atlantic Water (MAW); however, it was the highest in N Adriatic Surface waters (NAdSW) and consequently in outflowing Adriatic Deep Waters (AdDW). In deep water profiles the portion of DGM typically increased at depths with oxygen minimum and then towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea), indicating its bacterial and/or geotectonic origin. During oceanographic cruises in 2011 and 2015 in the Tyrrhenian Sea, novel methods for continuous DGM determination in surface waters (Wangberg and Gardfeldt, 2011, Begu et al., 2016) were applied and compared to the standard method, and showed good agreement.
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•Dissolved gaseous mercury (DGM) was studied in surface and deep waters of the Mediterranean Sea.•DGM represents a considerable portion of THg (average 20%) in Mediterranean waters.•Novel methods for continuous DGM determination in surface waters were applied and compared to standard method
We collected a sediment core from the 6th (6J) Triglav Lake, a remote mountain lake in NW Slovenia, and analysed it for 25 elements, using
k
0
-instrumental neutron activation analysis (
k
0
-INAA). ...For Hg, we used cold vapour atomic absorption spectrometry (CVAAS). Data were analysed using Principal Component Analysis (PCA). PCA indicated several distinct groups of elements and sediment core samples. Ca distribution was entirely different from all other sediment components. Ba, Br, Hg, Sb and Zn were associated with organic matter (OM), with Hg showing the strongest affinity to OM. As, Cr, Fe and U formed a group of redox-sensitive elements. Two events that occurred ca. 1915 and in the 1940s/1950s, were identified in the core. They were associated with increased inputs of allochthonous material into the lake, and significantly affected the stratigraphic distributions of all elements. Some trace elements, such as As, Hg and Zn, are probably effectively retained in the catchment, whereas Cr tends to be readily exported from the catchment. Atmospheric deposition affected not only elements of anthropogenic origin (As, Ba, Br, Hg, Sb, Zn and Cr) that started to increase after the 1970s, but also those of terrestrial origin (Ca, Fe, Na). Introduction of fish into the lake in 1991 and the subsequent increase in primary production, affected the distribution of Ca and elements that are redox-sensitive and/or associated with OM (As, Ba, Fe, Sb, U, Zn). Fe minerals in uppermost 6J sediments have a strong influence on the distribution of several trace elements. As and Zn closely tracked Fe, whereas Sb was likely released after oxidation. Climate change could also have enhanced inputs of elements from the catchment, but such changes were likely overwhelmed by the effects of increased eutrophication.
In this study, seasonal changes of mercury (Hg) species in the highly variable estuary of Soča/Isonzo River (northern Adriatic Sea) were investigated. Samplings were performed on a seasonal basis ...(September 2009, May, August and October 2010) and Hg species (total Hg, methylmercury (MeHg), dissolved gaseous Hg (DGM)) in waters, sediments and pore waters were determined. In addition, a range of ancillary parameters were measured (salinity, nutrients, organic carbon (OC), nitrogen species). Hg values were interpreted using these parameters and hydrological conditions (river flow, wave height) around the time of sampling. There were no significant changes in Hg load from river to the gulf, compared to previous studies. The load was temporarily higher in May 2010 due to higher river flow. Wave height, through changing hydrostatic pressure, was most likely to cause resuspension of already deposited Hg from the bottom (August 2010). The estuary is a net source of DGM to the atmosphere as suggested by DGM profiles, with salinity, redox potential and organic matter as the most probable controls over its production. MeHg is produced in situ in sediment or in water column, rather than transported by river, as indicated by its correlation with OC of the marine origin. Calculated fluxes for THg and MeHg showed sediment as a source for both the water column. In pore waters, OC in part affects partitioning of both THg and MeHg; however other factors (e.g. sulphide and/or oxyhydroxides precipitation and dissolution) are also probably important.
► Water, sediment and pore water mercury species in front of Soča River estuary were measured. ► Seasonally variable hydrological conditions were shown to influence water column Hg speciation. ► Fluxes for total Hg and MeHg from sediment to water were calculated. ► Sediment is a source of total Hg and MeHg to the water column. ► Correlation of MeHg with organic carbon of marine origin suggests in situ formation.
Continuous dissolved gaseous mercury (DGM) measurements were performed during the summer months (May to September 2019) in the Gulf of Trieste (northern Adriatic Sea), a well-studied contaminated ...site due to releases of mercury from the former mercury mine Idrija in Slovenia. Continuous DGM data were regularly checked by the discrete manual method to assure traceability and comparability of the results and used for the calculation of the upward flux of Hg(0) between the water and the air compartment, using the gas exchange model applied in previous studies in the Mediterranean Sea. DGM concentrations measured by continuous and discrete methods showed good agreement, 68.7 and 73.5 ng·m−3, respectively. The diurnal DGM variability examined by sorting the DGM concentrations in 24 1-h intervals was extremely low (68.3–69.2 ng·m−3). Various environmental parameters measured at oceanographic buoy Vida, and the nearby stations were used to determine the relationship between DGM and the individual environmental parameters. The correlation with the oxygen saturation was pronounced during the July high DGM event (R2 = 0.70, p < 0.05), and the gradient between the bottom and surface temperature was correlated with both DGM peaks in June and July (R2 = 0.42 and R2 = 0.43, p < 0.05). Transport from the more polluted northern part of the Gulf was determined as the most probable source of both high DGM events. The computed average annual Hg(0) flux across the water–air interface (5.13 ng·m−2·h−1) was lower than those reported in recent studies. We assume that for an appropriate assessment of the Hg evasion flux and of the temporal DGM variability in such heterogeneously polluted coastal areas, both spatial and temporal coverage are required.
Wet deposition is the main source of mercury (Hg) from the atmosphere to the Earth’s surface. However, the processes that govern the dispersion of deposited Hg in seawater are currently not well ...understood. To address this issue, total mercury (THg) concentrations in surface seawaters and precipitation were determined on a monthly basis in the Bay of Kaštela (Central Adriatic Sea). Following the assumption that deposited THg is diluted in the seawater bulk due to mixing processes, an exponential decay-like model was developed and the wet deposition of THg was normalized based on periods between precipitation events and seawater sampling. Normalized wet deposition of THg showed significant correlation with the THg gradient in surface seawater after removal of an outlier. To explain the observed outlier, further data normalization included wind data to account for enhanced seawater mixing due to strong winds. Wind-normalized THg deposition of all datapoints showed significant correlation with the THg gradient in surface seawater. The correlation showed that the THg gradient in surface seawater of 0.378 pg L−1 m−1 corresponds to THg wet deposition of 1 ng m−2 after including the influence of wind speed on seawater mixing.
500 years of mercury (Hg) mining in the town of Idrija has caused severe pollution in Idrija and its surroundings. Following the closure of the mine in 1995, the environment remains contaminated with ...Hg. Sources of elemental-, inorganic- and methyl Hg exposure were identified, potential environmental level of exposure to Hg was evaluated and actual internal exposure to Hg was assessed in selected susceptible population groups comprising school-age children and pregnant women living in Idrija and in control groups from rural and urban environments. The study of pregnant women (n=31) was conducted between 2003 and 2008, and the study of school-age children (n=176) in 2008. Potential interaction of Hg with selenium (Se) in plasma was assessed in both study populations, while in pregnant women antioxidative enzyme activity (glutathione peroxidase, superoxide dismutase and catalase) in erythrocytes of maternal and cord blood was also assessed. Actual exposure to Hg as indicated by levels of Hg in children's blood (geometric mean (GM) 0.92µg/L), mother's blood (GM 1.86µg/L), children's urine (GM 1.08µg/g crea.), mother's urine (GM 2.51µg/L), children's hair (GM 241ng/g) and mother's hair (GM 251ng/g) was higher in the two study groups from Idrija than in the control groups from rural areas, but was still at the level of a “normal” population and reflects mainly exposure to elemental Hg (Hg°) from dental amalgam and, to a certain extent atmospheric Hg°. Furthermore, the internal doses of Hg received during pregnancy did not decrease the bioavailability of Se. Based on observation in children, the increase in Se protein expression is suggested to be a consequence of moderately elevated exposure to Hg°. The observed changes in activity of antioxidative enzymes, as biomarkers of oxidative stress, appear to be mainly associated with pregnancy per se and not with an increased exposure to Hg. In view of the continuing increased potential for Hg exposure and the low number of pregnant women studied, the results warrant a further longitudinal study of a larger group of pregnant women residing in the area of the former mercury mine.
•Estimated environmental Hg exposure in the town of Idrija still poses a potential risk to susceptible groups of inhabitants.•Actual internal exposure reflects mainly exposure to Hg° from dental amalgam and, to a certain extent atmospheric Hg°.•The internal doses of Hg received in the Idrija children and pregnant women did not decrease the bioavailability of Se.•Changes in activity of antioxidative enzymes were not associated with exposure to Hg in the town of Idrija.
Mercury speciation and its distribution in surface and deep waters of the Mediterranean Sea were studied during two oceanographic cruises on board the Italian research vessel URANIA in summer 2003 ...and spring 2004 as part of the Med Oceaneor and MERCYMS projects. The study included deep water profiles of dissolved gaseous Hg (DGM), reactive Hg (RHg), total Hg (THg), monomethyl Hg (MeHg) and dimethyl Hg (DMeHg) in open ocean waters. Average concentrations of measured Hg species were characterized by seasonal and spatial variations. Overall average THg concentrations ranged between 0.41 and 2.65 pM (1.32
±
0.48 pM) and were comparable to those obtained in previous studies of the Mediterranean Sea. A significant fraction of Hg was present as “reactive” Hg (average 0.33
±
0.32 pM). Dissolved gaseous Hg (DGM), which consists mainly of Hg
0, represents a considerable proportion of THg (average 20%, 0.23
±
0.11 pM). The portion of DGM typically increased towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea), indicating its geotectonic origin. No dimethyl Hg was found in surface waters down to the depth of 40 m. Below this depth, its average concentration was 2.67
±
2.9 fM. Dissolved fractions of total Hg and MeHg were measured in filtered water samples and were 0.68
±
0.43 pM and 0.29
±
0.17 pM for THg and MeHg respectively. The fraction of Hg as MeHg was in average 43%, which is relatively high compared to other ocean environments. The concentrations reported in this study are among the lowest found in marine environments and the quality of analytical methods are of key importance. Speciation of Hg in sea water is of crucial importance as THg concentrations alone do not give adequate data for understanding Hg sources and cycling in marine environments. For example, photoinduced transformations are important for the presence of reactive and elemental mercury in the surface layers, biologically mediated reactions are important for the production/degradation of MeHg and DGM in the photic zones of the water column, and the data for DGM in deep sea indicate the natural sources of Hg in geotectonicaly active areas of the Mediterranean Sea.
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