Biogeochemical arsenic cycling in a Paleoarchean ocean basin

GSTDTAP

项目编号	1452347
	Biogeochemical arsenic cycling in a Paleoarchean ocean basin
	Kimberly Myers
主持机构	Myers Kimberly D
项目开始年	2015
	2015-06-01
项目结束日期	2017-05-31
资助机构	US-NSF
项目类别	Fellowship
项目经费	87000(USD)
国家	美国
语种	英语
英文摘要	Dr. Kimberly D. Myers has been awarded an NSF Earth Sciences Postdoctoral Fellowship to investigate evidence for arsenic cycling in 3.2 billion-year-old Fig Tree Group sediments within the Barberton Greenstone Belt, South Africa. Microorganisms control arsenic redox reactions in modern near surface environments. Arsenic (As) metabolism also may have played an important role in Archean microbial ecosystems; however, current models of microbial arsenic cycling in the Archean are poorly constrained by observations in the sedimentary record. Arsenopyrite (FeAsS) was discovered within hematite-rich sediments deposited in a shallow marine setting. Preliminary analyses demonstrated that the As in FeAsS was introduced as As(III) or As(V) during or shortly after these iron rich sediments were deposited, then later reduced, indicating a complex arsenic redox cycle in the Fig Tree basin that may have involved microbial activity. This research will generate results of significant interest to several earth- and life-science research themes. It will improve our understanding of arsenic behavior in Archean surface environments and may uncover evidence for the earliest microbially driven arsenic cycle on Earth, a subject of interest to many environmental and evolutionary microbiologists. This work will also contribute to our understanding of arsenic mobility in modern reducing sediments, and could inform remediation efforts for arsenic-contaminated aquifers that negatively impact the health of millions of people worldwide. In conjunction with Texas A&M University Libraries, Dr. Myers will also be participating in a nation-wide effort to provide open-access learning materials to university students as a low cost alternative to traditional textbook resources. She will compose a chapter for an open-access introductory Geology textbook comparing the Earth's geochemical cycles before and after the Great Oxidation Event. The text will include online learning modules following the story of this NSF-funded research project from design to execution to motivate young geoscientists, especially women, and reinforce the role of creativity in scientific achievement. Dr. Myers will perform her research in conjunction with the Department of Geology and Geophysics at Texas A&M University and the Lamont-Doherty Earth Observatory, Columbia University. She will conduct fieldwork in South Africa to further characterize As-containing jasper deposits. Rock samples will be examined using arsenic K-edge absorption spectroscopy, and μ-XRF. A multi-faceted experimental and analytical approach will be used to understand how As was introduced, retained, and preserved in the Fig Tree Group sediments. The mechanisms for As introduction and retention in Fe-oxy-hydroxide and silica rich amorphous solids will be examined experimentally, with a specific focus on impact of the oxidation state of As, and the effect of microorganisms on the adsorption and retention of As(III) and As(V) to sediments under anaerobic conditions. The precipitation of arsenopyrite will then be examined in these Fe- and silica-rich solids both abiotically in the presence of sulfide, and in the presence of a consortium of As-, Fe-, and S-reducing microorganisms. Experimental material will be examined using SEM-EDS, Raman spectroscopy, and arsenic K-edge absorption spectroscopy, to obtain a robust model for the (bio)geochemical behavior of arsenic in the Archean Fig Tree depositional basin.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/67990
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Kimberly Myers.Biogeochemical arsenic cycling in a Paleoarchean ocean basin.2015.