Mercury Speciation in Sediments Affected by Dumped Mining Residues in the Drainage Area of the Idrija Mercury Mine, Slovenia

Abstract

Mercury (Hg) concentrations and Hg phases were investigated in contaminated sediments and flooded soils in the drainage area of the Idrija Hg mine, Slovenia. The main aim of this study was the analytical separation and quantification of cinnabar (HgS) and noncinnabar Hg compounds in sediments contaminated by mining residues. Separation of Hg phases was performed by means of a solid-phase-Hg-thermo-desorption technique complemented by selective extraction of organically bound Hg. Speciation measurements indicate the occurrence of two major Hg forms: cinnabar the primary ore and an unspecified group of matrix-bound, noncinnabar Hg compounds. The results show that Hg concentrations and dispersion of the two Hg phases within the river system depend on the distribution of different sediment grain size fractions. Accumulation of cinnabar predominately occurs in coarse grained river sediments, where it constitutes on average more than 80% of total Hg (up to 1000 mg/kg) in present- and past day sediments. In contrast noncinnabar Hg was found to be enriched in areas where fine grained material was deposited reaching up to 40% of Hgtot (1−60 mg/kg) in flooded soils and up to 55% (<1−18 mg/kg) in sediments of the Gulf of Trieste.

Geochemistry and environmental threats of soils surrounding an abandoned mercury mine

“…Thus, we assume that most Hg present in the calcine material is bound to mineral components mainly by iron oxides, which were formed when the cinnabar-bearing ore was being roasted. Earlier studies already suggested that Hg 0 formed during thermal breakdown of cinnabar is re-condensed during cooling of the material and adsorbed to iron oxide surfaces (Biester et al 2000). In addition to matrix-bound Hg, some calcine samples contained traces of cinnabar.…”

Speciation of mercury in fly ashes by temperature programmed decomposition

“…The next Hg compounds to decompose are the mercury sulphides between 170 and 330ºC. As noted by Lopez-Anton et al [22], there are two different HgS crystalline structures: cubic black HgS or metacinnabar which decomposes at 265ºC and trigonal red HgS or cinnabar which decomposes at 290ºC [22,24]. HgO and HgSO 4 decompose at higher temperatures than mercury sulphides.…”

“…HgCl 2 <HgS<HgO<HgSO 4 ) according to the temperature of desorption [22]. Thermal decomposition has been used to identify Hg compounds in soil contaminates, sediment samples, iron-based sorbents [23][24][25], and even in mercury lamp wastes [26]. However, there is a lack of a similar knowledge concerning the speciation of Hg in coal combustion products [27].…”

Distribuição e especiação de mercúrio em sedimentos de áreas de garimpo de ouro do quadrilátero ferrífero (MG)

“…Estudos anteriores, com um sistema de termodessorção acoplado a um espectrômetro de absorção atômica, mostraram que diferentes espécies de mercúrio são liberadas da matriz, por aquecimento, a diferentes faixas de temperatura [14][15][16][24][25][26][27] . Nas mesmas condições A Figura 5 mostra termogramas representativos de todas as amostras analisadas, provenientes dos diferentes locais de amostragem.…”

“…Algumas amostras apresentaram ombros ao lado do pico principal, indicando a presença de mais de um tipo de ligação de Hg na matriz. Esse tipo de perfil já foi observado em outros trabalhos 15,26 e foi atribuído a complexos organominerais.…”