Isotopic insights into biological regulation of zinc in contaminated systems
Procedia Earth and Planetary Science
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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.
| 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) | Crustal Geophysics and Geochemistry Science Center, Fort Collins Science Center, Geology, Minerals, Energy, and Geophysics 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 |
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