Mercury fractionation in contaminated soils from the Idrija mercury mine region

Abstract

Mercury (Hg) fractionation was investigated in contaminated soil in the Idrija Hg-mine region, Slovenia. The main aim of this study was to test and apply sequential extraction and quantification of different Hg phases in order to estimate the mobility and potential bioavailability of Hg in contaminated soils. Separation of Hg phases was performed by means of a selective sequential extraction procedure complemented by volatilization of elemental mercury (Hg0). The influence of temperature, moisture and storage on Hg0 volatilization was also investigated. The total Hg concentrations varied between 8.4 and 415 mg kg(-1) and were up to 40-fold higher than the maximum permissible set by Slovenian legislation. Fractionation measurements indicated cinnabar as the predominant Hg fraction, followed by Hg0. Accumulation of cinnabar predominantly occurred in coarse grained flood plain sediments, where on average it constituted more than 80% of total Hg. In contrast non-cinnabar fractions were found to be enriched in areas where fine grained material was deposited, reaching up to 60% of total Hg. The strong positive correlation (R2 = 0.71-0.99) among non-cinnabar fractions suggested that these fractions predominantly control the mobility and potential bioavailability of Hg. Sample pretreatment before fractionation influenced the partition of Hg between different fractions, and therefore fractionation in fresh, nontreated samples is suggested. In addition, the specificity of the extraction steps needs further attention, as it was shown that some extraction steps, such as the organo-chelating Hg fraction, do not provide meaningful results. This further suggests that protocols for mercury fractionation need further harmonization in order to improve the comparability of the results and their use in risk assessment. Volatile mercury fluxes averaged between 0.04 and 6.5 ng g(-1) h(-1). Good agreement (R2 = 0.81-0.95) was found between the non-cinnabar fractions and evaporation of Hg0. Both the temperature and sample moisture had significant effects on mercury volatilization. The results in this study were obtained at 70 degrees C, which may be somewhat high, in particular for bacterial activity which may also play an important role in Hg volatilization. Therefore it is strongly suggested that further optimisation of the protocol to assess Hg volatilization from soil is required.

Extractability and mobility of mercury from agricultural soils surrounding industrial and mining contaminated areas

“…Recoveries lower than 100% can be also justified by the lack of homogeneity of the sample, but can also result from losses of volatile mercury during the process. The same problem was observed by Kocman et al (2004). Better recoveries were obtained for industrial soil samples, probably because of soil characteristics.…”

A laboratory based experimental study of mercury emission from contaminated soils in the River Idrijca catchment

“…The distribution of Hg in this area in various environmental compartments has been extensively studied in the past (Grönlund et al, 2005;Horvat et al, 2002;Hines et al, 2006;Biester et al, 2002;Gosar et al, 2006;Žižek et al, 2007;Kotnik et al, 2005). Mercury fractionation study of contaminated soils in the town of Idrija performed by Kocman et al (2004) indicated cinnabar as the predominant Hg fraction in these soils, especially in coarse grained alluvial soils where on average it constituted more than 80% of total Hg. Similar, Gosar et al (2006) observed relatively enriched cinnabar bound mercury in soils closer to the pollution sources in the town of Idrija, while at locations more distant from the pollution sources, soils were found to be enriched in non-cinnabar mercury forms (Gosar et al, 2006).…”

“…Grönlund et al (2005) estimated the average mercury flux from the most polluted sites in the town of Idrija to be approximately 2-4 g h −1 , using the differential absorption lidar technique. Furthermore, simulation of mercury evaporation from different soil types from the Idrija region was performed and complemented by a selective sequential extraction procedure in order to assess the potential for mercury volatilization by Kocman et al (2004). In that study the effect of soil temperature, soil moisture, as well as specific mercury binding in soil on its volatilization was observed.…”

Impacto De La Minería Del Oro Asociado Con La Contaminación Por Mercurio en Suelo Superficial De San Martín De Loba, Sur De Bolívar (Colombia)

“…Varios estudios han reportado niveles de este elemento en suelo superficial por diferentes fuentes tales como la industria (Loska et al 2004, Yaylali-Abanuz 2011) y la minería (Kocman et al 2004). Las actividades antrópicas son las que provocan mayor acumulación, la cual puede ser varias veces superior al contenido en áreas no contaminadas.…”