Uptake Kinetics of Methylmercury in a Freshwater Alga Exposed to Methylmercury Complexes with Environmentally Relevant Thiols

Skrobonja, Aleksandra (author): Umeå universitet,Kemiska institutionen,Erik Björn's research group

Soerensen, Anne L. (author): Stockholms universitet,Institutionen för miljövetenskap och analytisk kemi

(creator_code:org_t)

2019-11-04
2019
English.
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 53:23, s. 13757-13766

Related links:: https://urn.kb.se/re...; show more...; https://doi.org/10.1...; https://urn.kb.se/re...; show less...

Abstract Subject headings

Cellular uptake of dissolved methylmercury (MeHg) by phytoplankton is the most important point of entry for MeHg into aquatic food webs. However, the process is not fully understood. In this study we investigated the influence of chemical speciation on rate constants for MeHg accumulation by the freshwater green microalga Selenastrum capricornutum. We used six MeHg-thiol complexes with moderate but important structural differences commonly found in the environment. Rate constants for MeHg interactions with cells were determined for the MeHg-thiol treatments and a control assay containing the thermodynamically less stable MeHg0H complex. We found both elevated amounts of MeHg associated with whole cells and higher MeHg association rate constants in the control compared to the thiol treatments. Furthermore, the association rate constants were lower when algae were exposed to MeHg complexes with thiols of larger size and more branched chemical structure compared to complexes with simpler structure. The results further demonstrated that the thermodynamic stability and chemical structure of MeHg complexes in the medium is an important controlling factor for the rate of MeHg interactions with the cell surface, but not for the MeHg exchange rate across the membrane. Our results are in line with uptake mechanisms involving formation of MeHg complexes with cell surface ligands prior to internalization.

By the author/editor: Skrobonja, Aleks ...; Gojkovic, Zivan; Soerensen, Anne ...; Westlund, Per-Ol ...; Funk, Christiane; Björn, Erik

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Chemical Science ...; and Other Chemistry ...

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