Total mercury, organic mercury and mercury fractionation in soil profiles from the Almadén mercury mine area

Abstract

Soil profiles located in the mining district of Almadén were investigated for total Hg, organic Hg fraction and Hg distribution by selective sequential extraction. A four-step sequential extraction method (labile Hg species, humic and fulvic complexes, elemental Hg and bound to crystalline oxides and Hg sulfide and refractory species) was performed. Total Hg concentrations ranged from 13 to 64 mg per kg dry mass. A clear relationship between the depth and Hg content was found since Hg concentration decreases downwards, which is indicative of anthropogenic contamination via deposition processes from nearby mine waste. Significant organic Hg concentrations were found in all the tested soil profiles ranging from 79 to 287 μg kg(-1) (dry weight). It seems that organic Hg was strongly influenced by elemental Hg (r = 0.79) and to a lesser extent by the organic carbon content (r = 0.57). The fractionation revealed that Hg exists mainly as cinnabar in the studied soils, which is one of the least available and mobile Hg species, and as elemental Hg as well. The most mobile Hg fractions only accounted for 3.2 to 7.7% of the total Hg content, with the main contribution being the humic and fulvic complexes fraction. The elemental Hg fraction increased with depth indicating a migration to deeper soil layers. In contrast, the surface layers showed an enrichment in the fraction bound to sulfide, which means that Hg is mostly deposited as cinnabar particles from non-processed ore in this area.

Mercury vertical and horizontal concentrations in agricultural soils of a historically contaminated site: Role of soil properties, chemical loading, and cultivated plant species in driving its mobility

“…Mercury mobility, as well as its bioavailability, in soils is strictly associated to its chemical forms, therefore the measurement of total Hg concentration is not generally sufficient to fully evaluate Hg fate in soil and in the surrounding environmental media (air, water, biomass). For example, cinnabar (α-HgS) is among the most stable Hg form in soils, whereas CH 3 Hg + can be bioaccumulated through the food web (Bavec and Gosar, 2016;Fernández-Martínez and Rucandio, 2014). For this reason, the use of sequential extraction procedures (Bloom et al, 2003) should be preferred as a specific approach to discriminate among the forms of Hg present in soils.…”

Carbon materials loaded with maghemite as regenerable sorbents for gaseous Hg0 removal

“…The amount of Hg found in the F1 and F2 fractions (Table 1) was negligible and Hg was totally recovered in the F3 fraction (~ 99%). The compounds extracted from the F3 fraction correspond to elemental Hg or species bound to crystalline oxides such as maghemite [27,41]. Taking into account that the results obtained by XPS indicate the consumption of oxygen due to its participation in oxidation processes (Table 4 and Fig CO2 (70%), N2(20%) and O2(10%).…”

Preliminary study of the distribution and risk assessment of mercury in different surficial sediments along the coastal area of the province Thai Binh in Vietnam

“…We suppose that this plant might have produced mercurial pesticides in the past. On the other hand, the contamination in soils close to mercury mine area was predominant as sulphide form [51]. Meanwhile, the predominance of mercury pollution in the soils close to a coal-fired power plant was elemental form [52,53].…”