Isotopic insights into biological regulation of zinc in contaminated systems

Procedia Earth and Planetary Science
By: , and 

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Abstract

Aquatic organisms use a variety of biogeochemical reactions to regulate essential and non-essential trace metals. Many of these mechanisms can lead to isotopic fractionation, thus measurement of metal isotopes may yield insights into the processes by which organisms respond to metal exposure. We illustrate these concepts with two case studies, one involving an intra- and the other an extra-cellular mechanism of Zn sequestration. In the first study, the mayfly Neocloeon triangulifer was grown in the laboratory, and fed a diet of Zn-doped diatoms at Zn levels exceeding the requirements for normal mayfly life functions. The N. triangulifer larvae consumed the diatoms and retained their Zn isotopic signature. Upon metamorphosis, the subimago life stage lost Zn mass either in the exuvia or by excretion, and the Zn retained was isotopically enriched. Thus, Zn uptake is nonfractionating, but Zn regulation favors the lighter isotope. Thus the Zn remaining in the subimago was isotopically heavier. In the second study, Zn was adsorbed on the cell walls and exopolysaccharide secretions of cyanobacteria, which favored the heavier Zn isotope. Continued adsorption eventually resulted in nucleation and biomineralization of hydrozincite {Zn5(CO3)2(OH)6}. These case studies demonstrate the utility of Zn isotopes to provide insights into how aquatic insects respond to metal exposure.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Isotopic insights into biological regulation of zinc in contaminated systems
Series title Procedia Earth and Planetary Science
DOI 10.1016/j.proeps.2015.07.014
Volume 13
Year Published 2015
Language English
Publisher Elsevier
Contributing office(s) Geology, Minerals, Energy and Geophysics Science Center, Crustal Geophysics and Geochemistry Science Center
Description 4 p.
First page 60
Last page 63
Conference Title 11th Applied Isotope Geochemistery Conference AIG-1
Conference Location Orléans, France
Conference Date September 21-25, 2015