Pavel Coufalík

Determination of mercury species using thermal desorption analysis in AAS

Analytical aspects of the determination of inorganic mercury (Hg) species by thermal desorption followed by atomic absorption spectrometry (AAS) detection were investigated in this work. Characteristic Hg release curves of the following species were observed: Hg0, HgCl2, HgO, HgSO4, HgS, and the Hg bound to humic acids. Particular attention was dedicated to the thermal stability and change of bond of Hg0 in the following matrices: sand, kaolinite, granite, peat, power plant ash, and soil. The bond of elemental Hg in environmental materials was described on basis of this experiment. Contaminated soil samples from two locations in the Czech Republic were investigated by thermal desorption analysis. Afterwards, the contents of volatile and plant-available Hg in the studied samples were determined. The determination of Hg0 using the thermal method was related to the results of liquid sequential extraction. The development of Hg speciation and the stability of Hg were assessed on basis of the data obtained. Thus, the analytical procedure used is a suitable tool for the study of inorganic Hg species in contaminated soils.

Sequential extraction and thermal desorption of mercury from contaminated soil and tailings from Mongolia

AbstractMercury forms in contaminated environmental samples were studied by means of sequential extraction and thermal desorption from the solid phase. The sequential extraction procedure involved the following fractions: water soluble mercury, mercury extracted in acidic conditions, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS, and residual mercury. In addition to sequential extraction, the distribution of mercury species as a function of soil particles size was studied. The thermal desorption method is based on the thermal decomposition or desorption of Hg compounds at different temperatures. The following four species were observed: Hg0, HgCl2, HgS and Hg(II) bound to humic acids. The Hg release curves from artificial soils and real samples were obtained and their applicability to the speciation analysis was considered.

Ultra-trace analysis of Hg in alkaline lavas and regolith from James Ross Island

Abstract Polar regions represent a unique environment for the study of mercury cycling in the global ecosystem. Our research was focused on the assessment of the origin and mobility of mercury in the geochemical cycle in Maritime Antarctic (James Ross Island) by means of atomic absorption spectrometry. Mercury content in a set of extrusive (subaerial, subaqueous) and intrusive (dyke) alkaline basalts ranged between 1.6 µg kg-1 (for samples without xenoliths) and 8 µg kg-1 (for samples containing crustal xenoliths). The mercury content in alkaline basalts indicates a very low concentration of mercury in peridotitic mantle sources. Samples of regolith from James Ross Island were subjected to a comprehensive analytical procedure proposed for ultra-trace mercury concentrations involving fractionation and thermal analysis. Total mercury contents in regolith (2.7–11.3 µg kg-1) did not deviate from the natural background in this part of Antarctica. Additionally, the obtained results are about two orders of magnitude smaller than values formerly assumed for primary mercury contents in basaltic lavas. Our results from Antarctica were compared with mercury contents in basaltic rocks from Greenland and the findings were confirmed. It seems that the input of mercury of geological origin into the polar ecosystem is apparently lower than expected.

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

ABSTRACT 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.

Macro- and microelements in soil profile of the moss-covered area in James Ross Island, Antarctica.

The study of Antarctic ecosystem provides a valuable insight into the nature development on the Earth. Biocenosis formation and colonization of land by organisms are noticeable especially in newly-deglaciated areas. In this research, soil profile development in the coastal zone of James Ross Island was investigated. The main objective was the characterisation of soil horizons. The contents of As, Ca, Cd, Co, Cr,Cu, Fe, K, Mg, Mn, Ni, P, Se and Zn were measured using ICP-MS technique. Soil parameters like organic carbon content, pH and content of sub-63 micro_m fraction were also determined. Based on the results obtained, the mineral-depleted and mineral-enriched layers in the soil profile were distinguished. With increasing depth, the shallow soil profile consisted mainly of weathered regolith. Apparently, the basic processes which are prerequisite for the development of soil ecosystem in the studied area were confirmed.

The use of thermal desorption in the speciation analysis of mercury in soil, sediments and tailings

The thermal desorption of mercury from the solid phase coupled with atomic absorption spectroscopy (AAS) is useful and simple method of mercury speciation analysis of the environmental samples. The present work is focused on the mercury desorption use for soil, sediments and tailings study. The extensive experimental material of many authors was summarized in this work with regard to a critical confrontation of approaches used in data interpretation. The main emphasis was put on the most frequently observed forms as Hg0, Hg2+ bound to mineral or organic surfaces, Hg2+ bound to the most common ligands and HgS. A comprehensive conception of the usage possibilities of this method as suitable analytical tool for speciation analysis was the main aim. This work includes not only the preparation of calibration materials and the description of their desorption behaviour but also summarizes the interpretations of mercury release curves of real samples and becomes an effective tool for their evaluation.

Biodiversity of freshwater algae and cyanobacteria on deglaciated northern part of James Ross Island, Antarctica. A preliminary study

Freshwater algae and cyanobacteria have been studied at the James Ross Island (Ant- arctica) since the first Czech expedition to the James Ross Island area in austral summer of 2004. Main emphasis, however, has been devoted to cyanobacteria and diatoms. Therefore, recent knowledge on biodiversity of freshwater species of green algae is fragmentary. The main aim of presented study was to contribute to species list of green algae and cyanobacteria from James Ross Island. To evaluate species richness of algae and cyanobacteria, samples of water/mats from 6 different lakes, shallow ponds, and seepages located in northern deglaciated part of the James Ross Island were collected in austral summers 2012 and 2013, respectively. The samples were analysed using optical microscopy approach after transport to Czech laboratories. Algal and cyanobacterial taxa were determined according to morphological characteristics. Frequencies of individual taxa occurrence in samples were evaluated. Species richness differences between sampling sites was found. Dominating taxa differed between collection sites as well. Altogether, 41 algal and cyanobacterial taxa were found. Some species and genera: Cosmarium sp., Actinotaenium curtum, Staurastrum punctulatum and Chlorobotrys regularis are reported for James Ross Island for the first time. In some samples, there were some species that remained undetermined due to limitations of light microscopy and morphological approach.

Mercury associated with size-fractionated urban particulate matter: three years of sampling in Prague, Czech Republic

An analysis of suspended particulate matter, with an emphasis on the Hg chemical forms, is presented. Dust samples originating from an area highly affected by traffic pollution in the city of Prague (Czech Republic) were sampled over a period of three years from air-conditioner filters and fractioned by size. The samples were morphologically characterised by scanning electron microscopy. The main method used for the analysis of constituent mercury compounds was sequential extraction by leaching solutions in combination with thermal desorption. The total mercury content ranged from 0.37 mg kg−1 to 0.82 mg kg−1. It emerged that the mercury was distributed in a wide spectrum of forms, and various trends in the distribution of these forms among the different size classes were observed. The fraction leached by nitric acid (consisting of elemental and complex-bound mercury) was the main constituent of total mercury. The highest content of this fraction was observed in the finest particle size class. The heterogeneity of morphology of the material increased with the size fraction.

Determination of short-term changes in levoglucosan and dehydroabietic acid in aerosols with Condensation Growth Unit – Aerosol Counterflow Two-Jets Unit – LC-MS

Residential areas in urban agglomerations and also in the countryside are often burdened with high concentrations of aerosol in winter, this originating from local combustion sources. Aerosol sources can be identified by a monitoring of organic markers of biomass burning. Abundant markers of biomass and softwood burning are levoglucosan and dehydroabietic acid, respectively. The aim of this research was to develop an analytical method for the determination of levoglucosan and dehydroabietic acid in aerosol over short time periods involving aerosol sampling into liquid samples, quantitative pre-concentration of analytes, and their determination by liquid chromatography - mass spectrometry. A Condensation Growth Unit - Aerosol Counterflow Two-Jets Unit (CGU-ACTJU) sampler was used for the quantitative collection of aerosol directly into water. Dehydroabietic acid was pre-concentrated from the aqueous phase by solid phase extraction (C-18). Afterwards, levoglucosan in water samples was concentrated on a vacuum evaporator. The detection limits of levoglucosan and dehydroabietic acid were 28 ng m-3 and 5.5 ng m-3, respectively. The results obtained by the developed method were compared with an independent determination of both markers in aerosol by means of the sampling of aerosols on a filter and subsequent analysis by GC-MS. The developed method demonstrated sufficient agreement with the independent determination for generated standard aerosol as well as for urban aerosol over an eight-day winter campaign. The presented method allows the monitoring of concentration changes in biomass burning markers in 2-h intervals.

Nitrate and ammonium ions contents in field minibioreactors with Antarctic freshwater autotrophs

The content of nitrate and ammonium ions in aquatic environment is an important factor in the development of microorganisms colonies especially in low-nutrient environment. In this study, field experiments using small-volume minibioreactors were performed directly on the James Ross Island in Antarctica in order to describe changes in nitrate and ammonium ions contents in the Antarctic environment The ion concentrations in minibioreactors with local freshwater autotrophs was monitored for increased eutro- phication conditions. The content of nitrogen forms was determined in water samples taken from the minibioreactors regularly. Samples were taken to the laboratory of the Johann Gregor Mendel station where nitrogen content was evaluated using ion-selective electrodes. Furthermore, the freshwater autotrophs was subjected to basic taxonomic study. Closed system of the minibioreactors allowed the monitoring of nitrogen speciation changes which take place in the environment. These changes can be attributed to both the biological activity of microorganisms and external conditions. Increased eutrophication of water did not induce a rapid development of the freshwater autotrophs.