Assessing Mercury Mobility in Sediment of the Union Canal, Scotland, UK by Sequential Extraction and Thermal Desorption

Abstract

The mobility of mercury (Hg) was assessed in sediment from the Union Canal, Scotland, UK. Samples collected from the vicinity of a former munitions factory that manufactured mercury fulminate detonators were subjected to sequential extraction followed by cold vapor atomic absorption spectrometry (CVAAS) and direct analysis using thermal desorption (TD). The sequential extraction indicated that >75% of mercury (up to 429 mg kg-1) was in mobile forms, with <12% semi-mobile and <23% non-mobile species. In the TD method, >67% of the total Hg content was desorbed in the temperature range 100-250 °C consistent with species weakly attached to the mineral matrix (tentatively identified as an iron (oxy)hydroxideassociated species). This predominance of mobile mercury species may arise from a lack of association between Hg and either organic matter or sulfur in the sediments. Further investigation of Hg mobilization, transport and assimilation/biomagnification is required both to determine whether there is a need for remediation of the sediment and to improve understanding of the biogeochemical cycling of Hg in shallow, oxic, freshwater systems.

Can Sediments Contaminated by Mining be a Source of Mercury in the Coastal Environment Due to Dredging? Evidence from Thermo-Desorption and Chemical Speciation

“…The release of Hg species weakly associated with the sediment mineral matrix generally occurs at temperatures lower than 250°C (Biester et al 2000 ; Cavoura et al 2019 and references therein), whilst higher desorption temperatures are required to release Hg species strongly associated with organic compounds such as humic acids or present as α-HgS (Biester et al 2000 ).…”

Investigation of the relationship between Hg speciation in soil and human health and ecological risk assessment

“…Mercury (Hg) pollution in soils is a problem of major significance, which has severe impacts on human h ealt h (Greenwood, 1985;Takaoka et al, 2014) and the environment (Cavoura et al, 2019;Vermeer, Arm stro ng and Hatch, 1973). Mercury can exist in the enviro nment and in biological systems as metallic mercury (Hg 0 ), inorganic and organic mercuric (Hg 2+ ) Hg, and mercurous (Hg + ) forms (Liu, Cai and O'Driscoll (Eds), 2012).…”