Toxic metals in cyanobacterial mat of Big Lachman Lake, James Ross Island, Antarctica.

The northern part of James Ross Island is the largest deglaciated area in the Antarctic Peninsula region with a unique ecosystem created during the Late Glacial. This research aims to evaluate the degree of contamination of the locality with toxic metals (As, Hg, Cd, and Pb) through bioindicators in the aquatic environment-colonies of cyanobacteria and algae. For this purpose, bottom lake sediments of Big Lachman Lake were studied for contents of Fe, As, Hg, Cd, Pb, Cr, Co, Ni, Cu, and Zn, as well as samples of cyanobacterial mat, in which Fe, As, Hg, Cd, and Pb were determined. Metal contents were determined by means of inductively coupled plasma optical emission spectrometry and atomic absorption spectrometry. The contents of metals in sediments did not differ from the usual values in the area of the Antarctic Peninsula. The bioaccumulation of metals in cyanobacterial mat was evaluated by calculating enrichment factors (the calculation to Fe as a reference element). According to this method, moderate pollution of Big Lachman Lake was confirmed for Hg and Cd.

Determination of cadmium in lichens by solid sampling graphite furnace atomic absorption spectrometry (SS-GF-AAS).

The determination of trace metal contents directly from a solid sample is a trend in modern atomic spectrometry. The aim of this study was to develop an analytical method for the routine determination of Cd in lichens using solid sampling graphite furnace atomic absorption spectrometry (SS-GF-AAS). For the determination of Cd, the temperature program of the graphite furnace was optimized using a mixed matrix modifier (Pd + Mg (NO3)2 + Triton X-100). The limit of detection and the limit of quantification were 0.9 µg/kg and 3 µg/kg, respectively. The analytical method for Cd determination in the plant matrix was verified by the analysis of certified reference materials of lichens, seaweed, and rye grass. The developed procedure was applied to the study of Cd distribution in thalli of Usnea antarctica lichen from James Ross Island, Antarctica. The SS-GF-AAS analytical method is particularly suited for use in environmental studies and plant physiology (the microanalysis of anatomical structures).

Simultaneous determination of cadmium and iron in different kinds of cereal flakes using high-resolution continuum source atomic absorption spectrometry.

A method for simultaneous determination of cadmium and iron in cereal flakes using high-resolution continuum source graphite furnace atomic absorption spectrometry is presented. Sample digest is introduced into the graphite furnace together with Pd/Mg(NO3)2 modifier. The primary absorption line of cadmium and adjacent secondary line of iron are used for the determination. Atomization is performed as a two-step process in order to meet ideal conditions for both elements. Interference produced by molecular absorption of PO molecular bands is suppressed by correction model using least squares background correction. Using the proposed method, levels of cadmium and iron were determined in different kinds of cereal flakes, where both elements are of great interest. Working range (0.01-2 µg L-1 for Cd and 10-500 µg L-1 for Fe) was suitable for the determination of analytes in samples. The method is fast, robust, and may be routinely used routinely in the analysis of foodstuffs.

Correction to: Model of Mercury Flux Associated with Volcanic Activity.

The original version of this article contained a mistake in Fig. 2. The country names have been missed in the figure legend along with the X-axis. The corrected figure is given below.

Model of Mercury Flux Associated with Volcanic Activity.

Volcanic activity is one of the primary sources of mercury in the earth's ecosystem. In this work, volcanic rocks from four geotectonically distinct localities (the Czech Republic - intraplate, rift-related alkaline basaltic rocks; Iceland - hotspot/rift-related tholeiitic basaltic rocks; Japan - island arc calc-alkaline andesites; and Alaska - continental arc calc-alkaline dacites) were studied. Ultra-trace Hg contents in all samples ranged from 0.3 up to 6 µg/kg. The highest Hg content was determined for volcanic ash from Mount Redoubt (Alaska, USA). In the case of basaltic volcanic rocks, the obtained results are about two orders of magnitude smaller than values formerly assumed for primary mercury contents in basaltic lavas. They are close to predicted Hg contents in the mantle source, i.e. below 0.5 µg/kg. Hg degassing is probably a key process for the resulting Hg contents in material ejected during volcanic eruption, which is previously enriched by Hg in the shallow-crust.

The contents and distributions of cadmium, mercury, and lead in Usnea antarctica lichens from Solorina Valley, James Ross Island (Antarctica).

Lichens are efficient and cost-effective biomonitors of the environment. Their geographic distribution together with their slow growth rate enable investigation of the deposition patterns of various elements and substances. In this research, levels of cadmium, lead, and mercury in Usnea antarctica lichens in the area of James Ross Island, Antarctica, were investigated. The lichens were microwave-digested, and the metals were determined by means of atomic absorption spectrometry with graphite furnace and a direct mercury analyzer. Median total contents of Cd, Hg, and Pb were 0.04, 0.47, and 1.6 mg/kg in whole lichens, respectively. The bottom-up distributions of these metals in the fruticose lichen thalli were investigated, and it was revealed that the accumulation patterns for mercury and lead were opposite to that for cadmium. The probable reason for this phenomenon may lie in the inner structure of thalli. The total contents of metals were comparable with those published for other unpolluted areas of maritime Antarctica. However, this finding was not expected for mercury, since the sampling locality was close to an area with some of the highest mercury contents published for Antarctic lichens. In short, lichens proved their usability as biological monitors, even in harsh conditions. However, the findings emphasize the need to take into account the distributions of elements both in the environment and in the lichen itself.

Mercury species in formerly contaminated soils and released soil gases.

Total mercury (T-Hg), elemental mercury (Hg0), methylmercury (MeHg+), phenylmercury (PhHg+), and gaseous elemental mercury (GEM) species were determined in soils formerly contaminated by different processes from two sites in the Czech Republic. Analytical methods involved atomic absorption spectrometry (AAS) using a single-purpose Advanced Mercury Analyser AMA-254 and radiochemical neutron activation analysis (RNAA) for T-Hg determination, a thermal desorption method was used for Hg0 determination, gas chromatography coupled with atomic fluorescence spectrometry (GC-AFS) was employed for assay of MeHg+ and PhHg+, while GEM measurement was carried out using a portable Zeeman-AAS device Lumex RA-915+. The first sampling site was in the surroundings of a former PhHgCl-based fungicide processing plant next to Príbram (central Bohemia). Although the use of Hg-based fungicides as seed mordant have been banned, and their production stopped at the end of 1980's, highly elevated Hg contents in soil are still observed in the vicinity of the former plant, reaching T-Hg values >13mgkg-1. The second sampling site was an abandoned mining area named Jedová hora Hill near Horovice (central Bohemia), where cinnabar (HgS) was occasionally mined as by-product of Fe ores hematite and siderite. Mining activities have been stopped here in 1857. Very high contents of T-Hg are still found at this site, up to 144mgkg-1. In most cases we found a statistically significant correlation between T-Hg and Hg0 values regardless of the pollution source. On the contrary, insignificant correlation was observed neither between T-Hg and GEM values, nor between GEM and Hg0. Concentrations of the investigated organomercury species were above a limit of detection (LOD) only in the most contaminated samples, where their levels were about two to three orders of magnitude lower compared to those of T-Hg.

Leaching of mercury from seal carcasses into Antarctic soils.

More than 400 seal mummies and skeletons are now mapped in the northern part of James Ross Island, Antarctica. Decomposing carcasses represent a rare source of both organic matter and associated elements for the soil. Owing to their high trophic position, seals are known to carry a significant mercury body burden. This work focuses on the extent of the mercury input from seal carcasses and shows that such carcasses represent locally significant sources of mercury and methylmercury for the environment. Mercury contents in soil samples from the surrounding areas were determined using a single-purpose AAS mercury analyzer. For the determination of methylmercury, an ultra-sensitive isotopic dilution HPLC-ICP-MS technique was used. In the soils lying directly under seal carcasses, mercury contents were higher, with levels reaching almost 40 µg/kg dry weight of which methylmercury formed up to 2.8 % of the total. The spatial distribution implies rather slow vertical transport to the lower soil layers instead of a horizontal spread. For comparison, the background level of mercury in soils of the investigated area was found to be 8 µg/kg dry weight, with methylmercury accounting for less than 0.1 %. Apart from the direct mercury input, an enhanced level of nutrients in the vicinity of carcasses enables the growth of lichens and mosses with accumulative ability with respect to metals. The enhanced capacity of soil to retain mercury is also anticipated due to the high content of total organic carbon (from 1.6 to 7.5 %). According to the results, seal remains represent a clear source of mercury in the observed area.

Effects of the soil microbial community on mobile proportions and speciation of mercury (Hg) in contaminated soil.

The precise characterization of the behavior of individual microorganisms in the presence of increased mercury contents in soil is necessary for better elucidation of the fate of mercury in the soil environment. In our investigation, resistant bacterial strains isolated from two mercury contaminated soils, represented by Paenibacillus alginolyticus, Burkholderia glathei, Burkholderia sp., and Pseudomonas sp., were used. Two differently contaminated soils (0.5 and 7 mg kg(-1) total mercury) were chosen. Preliminary soil analysis showed the presence of methylmercury and phenylmercury with the higher soil mercury level. Modified rhizobox experiments were performed to assess the ability of mercury accumulating strains to deplete the mobile and mobilizable mercury portions in the soil by modification; microbial agar cultures were used rather than the plant root zone. A sequential extraction procedure was performed to release the following mercury fractions: water soluble, extracted in acidic conditions, bound to humic substances, elemental, and bound to complexes, HgS and residual. Inductively coupled plasma mass spectrometry (ICP-MS) and a single-purpose atomic absorption spectrometer (AMA-254) were applied for mercury determination in the samples and extracts. Gas chromatography coupled to atomic fluorescence spectrometry (GC-AFS) was used for the determination of organomercury compounds. The analysis of the microbial community at the end of the experiment showed a 42% abundance of Paenibacillus sp. followed by Acetivibrio sp., Brevibacillus sp., Cohnella sp., Lysinibacillus sp., and Clostridium sp. not exceeding 2% abundance. The results suggest importance of Paenibacillus sp. in Hg transformation processes. This genus should be tested for potential bioremediation use in further research.

Analysis of mercury and other heavy metals accumulated in lichen Usnea antarctica from James Ross Island, Antarctica.

The study was designed to investigate the content and distribution of selected heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Fe, Pb and Zn) in samples of fruticose macrolichen Usnea antarctica from James Ross Island. A special emphasis was devoted to mercury and its species (elemental mercury and methylmercury). It was found that mercury contents were relatively high (up to 2.73 mg kg(-1) dry weight) compared to other parts of the Antarctic Peninsula region, while the concentrations of most other elements were within reported ranges. Mercury contents in lichens originating from the interior were higher than those from the coast, which is probably the result of local microclimate conditions. Similar trends were observed for Hg(0) and MeHg(+), whose contents were up to 0.14 and 0.098 mg kg(-1) dry weight, respectively. While mercury did not show a significant correlation with any other element, the mutual correlation of some litophile elements probably refers to the influence on thalli of resuspended weathered material. The influence of habitat and environmental conditions could play an essential role in the bioaccumulation of contaminants rather than just the simple presence of sources. Thus, the study of the thalli of this species can bring a new perspective on the interpretation of contaminant accumulation in lichens of the polar region.

Seasonal variability of mercury contents in street dust in Brno, Czech Republic.

Environmental contamination by mercury carries serious risks to the biosphere. Urban agglomerations burdened with traffic are characterized by substantial dust levels, including high concentrations of pollutants bound to particulate matter. In this research, the content of particulate mercury in street dust was investigated in relation to the season and traffic intensity. In total, 80 street dust samples were collected in the centre of Brno (Czech Republic) in which total and bioaccessible mercury contents were determined. Total mercury content in the samples ranged from 0.03 to 2.67 mg/kg. The content of bioaccessible mercury was below the limit of quantification in all samples. Thus, street dust did not increase the daily mercury intake by the population in studied area. A clear trend of mercury accumulation in street dust depending on traffic intensity in the investigated streets was not observed over the whole year.

Stabilizing agents for calibration in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry.

Tetramethylene dithiocarbamate (TMDTC), diethyldithiocarbamate (DEDTC), and thiourea were investigated as stabilizing agents for calibration purposes in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS). These agents were used for complexation of mercury in calibration solutions and its thermal stabilization in a solid sampling platform. The calibration solutions had the form of methyl isobutyl ketone (MIBK) extracts or MIBK-methanol solutions with the TMDTC and DEDTC chelates and aqueous solutions with thiourea complexes. The best results were obtained for MIBK-methanol solutions in the presence of 2.5 g L(-1) TMDTC. The surface of graphite platforms for solid sampling was modified with palladium or rhenium by using electrodeposition from a drop of solutions. The Re modifier is preferable due to a higher lifetime of platform coating. A new SS-ETAAS procedure using the direct sampling of solid samples into a platform with an Re modified graphite surface and the calibration against MIBK-methanol solutions in the presence of TMDTC is proposed for the determination of mercury content in solid environmental samples, such as soil and plants.

Electrochemical modification of a graphite platform for a solid sampling electrothermal atomic absorption spectrometry of mercury.

An electrodeposited palladium and iridium/gold mixture has been investigated as a chemical modifier for mercury determination in environmental samples by solid sampling electrothermal atomic absorption spectrometry. Electrochemical procedures of platform surface modification performed in a cell with 20 ml of solution, and in a drop of modifier solution have been optimized. Simple electrolysis in a drop was found to be the most consistent, taking the reproducibility as the major criterion. A total mass of 250 µg of electrodeposited palladium or an iridium/gold mixture was used. The lifetime of 60 - 70 firings for a deposited iridium/gold mixture was smaller than that for palladium with a lifetime of 100 - 120 firings. The detection limit was 120 pg Hg. Different sample masses of between 0.1 and 10 mg were weighed into modified platforms according to the mercury content. The results obtained for mercury in environmental samples as soils, sediments and plant, using solid sampling and calibration against aqueous standards stabilized by potassium permanganate, were in good agreement with those achieved by using the thermal deposition of modifiers and with measurements by pyrolysis atomic absorption spectrometry with gold amalgamation.

Liquid chromatographic--cold vapour atomic fluorescence spectrometric determination of mercury species.

Solvent extraction, sonication, and microwave-assisted extractions in the presence of extraction agents (thioacetic acid, citric acid, cysteine, 2-mercaptoethanol, HCl + NaCl, etc.) were tested for the isolation of mercury species. A mixture of 6 M HCl and 0.1 M NaCl was selected as the most suitable extraction agent. The extraction efficiency was about 10% higher and the RSD below 3.3% when microwave-assisted extraction was applied instead of sonication. The liquid chromatography-cold vapour atomic fluorescence spectrometry (LC/CV-AFS) method was optimised and used for separation and determination of inorganic mercury cations and alkylated and arylated mercury species. Isocratic elution at a flow rate of 0.15 mL/min (with a mobile phase containing 0.05% 2-mercaptoethanol (pH = 5) and 7% methanol and with a stepwise increase of methanol content up to 100% MeOH in the 15th min) was used for separation of mercury species on a Hypersil BDS C18 RP column. The limits of detection of the LC/CV-AFS system were estimated as 0.2 microg/L (3%) for MeHg+, 0.07 microg/L (5.3%) for inorganic Hg, 0.06 microg/L (3.4%) for PhHg+, and 0.12 microg/L (4.4%) for EtHg with the corresponding RSDs at 5 microg/L (n = 10) given in parentheses. The concentrations (2-10 mg/kg fresh weight) of total mercury and methylmercury (90-99% of the total mercury) in selected fish obtained by HPLC/CV-AFS were in good agreement (absolute deviations 0.05 mg/kg) but more precise (RSDs <5.4% at 5 mg/L, n = 10) than those determined by GC coupled to an electron capture detector. The RSDs (3.1-8.2% and 4.1-9.0%) of the overall analytical procedure for the determination of total mercury (AMA 254) and methylmercury (HPLC/CV-AFS) were determined for intra-day and inter-day assays, respectively.