As a global pollutant and a metal toxic to living organisms, mercury is one of the most environmentally studied elements. The mercury cycle is a complex phenomenon due to transformations in various media and exchange between them. Thus, there is an incomplete understanding of the mercury cycle in the environment. The recent finding of Mass Independent Fractionation (MIF) of mercury isotopes (Bergquist and Blum, 2007; Ghosh et al., 2008) portend a new understanding of mercury isotopes and the mercury cycle in the environment. Different mercury isotopic features of different materials potentially indicate possible different transformations of mercury. This study attempts to define mercury isotopic features of plants and relate these with different photosynthetic pathways which are obtained by examining carbon isotopic signatures of plants. Plants were sub-sampled into leaves, stems and roots, with the understanding that if fractionation of mercury isotopes occurred in vivo, plants might be isotopically heterogeneous. Soil samples were also analyzed in this study to examine possible differences between plants and soils and also possible transformations inside the plants. Both C3 and C4 plants exhibit mass dependent and mass independent mercury isotope effects. Both C3 and C4 plants are enriched in light isotopes, but the degree of mass fractionation is approximately three times greater in C3 plants, than in C4 plants (-0.29‰/amu compared to -0.09‰/amu). Mercury in both C3 and C4 plants exhibit a MIF isotope effect as well; that being a depletion (generally less than 0.5‰) of the odd mass isotopes 199Hg and 201Hg. The one CAM plant studied contained mercury that is slightly heavy isotope enriched and with no clearly discernable MIF effect. These findings suggest a connection between the isotopic composition of mercury and the photosynthetic pathway of the plants. Leaves are slightly more fractionated than the roots are. The mass dependent effect is a light isotope enrichment of up to 1.54 ‰. Mass independent fractionation is a relative depletion of the odd mass isotopes with Δ199Hg ranging from -0.12 to -0.6 ‰. A difference in the MIF effect of root-leaf pairs seems to require different sources. Soils also showed similar isotopic feature with the plants samples. / A Thesis submitted to the Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for
the degree of Master of Science. / Summer Semester, 2010. / May 5, 2010. / Plants, Photosynthetic Pathway, Mercury Isotopes, Mass Independent Fractionation / Includes bibliographical references. / A. Leroy Odom, Professor Directing Thesis; Munir Humayun, Committee Member; Yang Wang, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_253419 |
| Contributors | Dogrul, Ayca (authoraut), Odom, A. Leroy (professor directing thesis), Humayun, Munir (committee member), Wang, Yang (committee member), Department of Earth, Ocean and Atmospheric Sciences (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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