Research and Teaching Interests
My research in biogeochemistry focuses on how geochemical, microbial, and anthropogenic processes affect the dynamic linked elemental cycles in modern, and paleo-environments. A variety of field- and laboratory-based techniques are applied to investigate the processes and feedbacks that promote and/or limit the transfer of elements (i.e., C, N, and P) and energy between different geological pools; including living and non-living organic matter as well as various inorganic reservoirs.
These studies require investigations of mechanisms that operate on time scales from days to millenia. The main goal is to gain a better understanding of the interactions between the physical, chemical and biological processes that control the distributions of these climatically important elements and how they change through time. Current research projects include: the characterization of dissolved organic matter in aquatic and marine systems, and investigation of the bioavailability and reactivity of dissolved organic compounds in natural waters. State-of-the-art analytical approaches are used to quantify and characterize organic matter in a broad range of natural systems (i.e., marine, aquatic and terrestrial), including the development of novel mass-spectrometric techniques for identifying and quantifying natural organic compounds. Ultimately this research seeks to develop more a mechanistic understanding of biogeochemical processes and how they relate to global scale patterns.
Some of my earlier research involved investigating the complex controls on organic carbon preservation in aerobic and anaerobic marine systems, development of a probe-inlet for MIMS analysis of atmospheric gases to measure microbial oxidation rates (e.g., oxygen consumption and denitrification) in sediments, and the chemical characterization of rainwater DOM.
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Representative Publications
"Molecular-level chemical characterization and bioavailability of dissolved organic matter in stream water using electrospray-ionization mass spectrometry," S.P. Seitzinger, H.E. Hartnett, R.J. Lauck, M. Mazurek. T. Minegishi, G. Spyres and R. Styles, Limnology and Oceanography 50, 1-12 (2005).
"High-resolution nitrogen gas profiles in sediment porewaters using a new probe for membrane-inlet mass spectrometry (MIMS).," H.E. Hartnett and S.P. Seitzinger, Marine Chemistry 83 (1-2), 23-30 (2003).
"Role of a strong oxygen deficient zone in the preservation and degradation of organic matter: a carbon budget for the continental margins of NW Mexico and Washington State," H.E. Hartnett and A.H. Devol, Geochimica et Cosmochimica Acta 67 (2), 247-264 (2003).
"Role of the oxygen minimum zone in transfer of organic carbon to the deep ocean," A.H. Devol and H.E. Hartnett, Limnology and Oceanography 46 (7), 1684-1690 (2001).
"Influence of oxygen exposure time on the preservation of organic carbon in continental margin sediments," H.E. Hartnett, R.G. Keil, J.I. Hedges and A.H. Devol, Nature 391, 572-574 (1998).
"Benthic oxygen fluxes and denitrification rates from high-resolution porewater profiles from the Western Antarctic Peninsula Continental Shelf," H.E. Hartnett, S. Boehme, C. Thomas, D. DeMaster and C. Smith, Deep-Sea Research In review, ().
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