A novel, robust field-sampling method for preserving dissolved mercury species associated with waters related to artisanal gold mining

King, David; Watts, Michael; Hamilton, Elliott; Mortimer, Robert; Di Bonito, Marcello. 2023 A novel, robust field-sampling method for preserving dissolved mercury species associated with waters related to artisanal gold mining. [Lecture] In: SEGH 2023. International Conference on Geochemistry and Health, University of Athens, Greece, 02-06 Jul 2023. (Unpublished)

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Abstract/Summary

Mercury (Hg) is imported to Kenya for use in artisanal and small-scale gold mining (ASGM) at the rate of 6-45 tonnes per year and a significant portion of this is released to the environment through the mining activities. However, the ability to measure and identify Hg and its species in environmental matrices, in particular aqueous samples such as river and drinking waters, is challenging due to the poor availability of technologies to provide representative measurements of Hg. Concentrations of most Hg species significantly decrease in water samples within 1 week of sampling if not preserved appropriately, being lost predominantly to headspace and container materials. Current preservation methods are inadequate for field use, particularly in challenging environments such as ASGM sites. This leads to under-representation of Hg emission and toxicity in waters, used around ASGM sites for drinking, agriculture, and aquaculture. Therefore, a robust method was necessary to provide measurements at sufficiently low Hg concentrations and avoid changes from field-collection to measurement, in particular where there is a delay such as from remote locations. The method must be sensitive, to provide useful public health and environmental regulatory information, and not require hazardous or expensive materials. A novel field-based solid-phase extraction method was developed to preserve Hg species from water samples for up to 4-weeks after sampling. Both inorganic (Hg2+) and methylated (MeHg) species were preserved and recovered >90% from water samples after 4-weeks of storage (n=5). This was then used to sample waters around ASGM sites in Kakamega, Kenya, as a proof-of-concept for the method.

Item Type:	Publication - Conference Item (Lecture)
Additional Keywords:	IGRD
Date made live:	12 Jan 2024 12:58 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/536611

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