Assessing Mercury Mobility in Sediment of the Union Canal, Scotland, UK by Sequential Extraction and Thermal Desorption
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% semimobile and < 23% nonmobile 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)hydroxide-associated 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.
The authors thank Scottish Canals (formerly British Waterways) for providing background information on the canal system and granting permission to sample.
- ATSDR (2013) Minimal Risk Levels (MRLs) Toxic substances portal. http://www.atsdr.cdc.gov/mrls/pdfs/atsdr_mrls_july_2013.pdf
- BS (2000) British Standards ISO 12880:2000: Characterisation of sludges: determination of dry residue and water content. British Standards Institution, LondonGoogle Scholar
- Faust SD, Osman MA (1981) Chemistry of natural waters. Science Publishers, Inc. Mercury, arsenic, lead, cadmium, selenium, and chromium in aquatic environments, Ann Arbor, pp 200–225Google Scholar
- Liu J, Jiang T, Wang F, Zhang J, Wang D, Huang R, Yin D, Liu Z, Wang J (2018) Inorganic sulfur and mercury speciation in the water level fluctuation zone of the Three Gorges Reservoir, China: the role of inorganic reduced sulfur on mercury methylation. Environ Pollut 237:1112–1123CrossRefGoogle Scholar
- Schumacher B (2002) Methods for the determination of total organic carbon (TOC) in soil and sediment US EPA Ecological risk assessment support centre Office of Research and Development US EPAGoogle Scholar
- Smith NA, Lassière OL (2000) Resolving mercury contamination in the Union Canal, Scotland in the millennium link—the rehabilitation of the Forth and Clyde and Union canals. G. Fleming Thomas Telford PublishingGoogle Scholar
- USEPA (2014) EPA METHOD 3200 Mercury species fractionation and quantification by microwave assisted extraction, selective solvent extraction and/or solid phase extractionGoogle Scholar