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Hilairy Hartnett | |
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| Alma mater | University of Washington |
| Scientific career | |
| Thesis | Organic carbon input, degradation, and preservation in continental margin sediments : an assessment of the role of a strong oxygen deficient zone (1998) |
Hilairy Ellen Hartnett is professor at the University of Washington known for her work on biogeochemical processes in modern and paleo-environments.
Hartnett has an A.B. from Vassar College (1990) and an M.S. from the University of Washington (1995). She earned her Ph.D. from the University of Washington in 1998. [1] Following her Ph.D. she did postdoctoral work at Rutgers University. She was a professor at Arizona State University from 2003 to 2024. [2] In January 2025 Hartnett moved to the University of Washington where she is a professor and director of the School of Oceanography. [3]
Hartnett's early research examined the impact of oxygen on preservation of organic carbon in sediments [4] and how regions of the ocean with low levels of oxygen impact the degradation of organic carbon. [5] She established high-resolution profiles of nitrogen in sediments [6] and examined the consumption of organic matter [7] as a postdoctoral researcher in Sybil P. Seitzinger's lab. More recently she has investigated how organic carbon changes as it is moved along in rivers, especially in the Colorado River [8] the reaction mechanisms of chemical reactions under hydrothermal conditions, [9] [10] and how wind-powered pumps could recover ice in the Arctic. [11] [12] In the realm of astrobiology, Hartnett has spoken about the possibility of life on other planets, [13] [14] how building blocks of life are formed, [15] [16] and about the possibility that the earliest forms of life were purple. [17]
In 2022, Hartnett was involved in the Mayflower AI sea drone project that is sending an autonomous vehicle across the Atlantic Ocean and will collect scientific data which will provide a detailed assessment of the state of the surface ocean. [18]
Hartnett's has an h-index of 29, with eleven papers receiving more than 100 citations. [19] Her most highly-cited paper introducing the concept of oxygen exposure time [4] received the 2022 John H. Martin Award from the Association for the Sciences of Limnology and Oceanography. [20]
In 2009 Hartnett received a National Science Foundation CAREER Awards. [8] In 2022, Hartnett received the John H. Martin Award from the Association for the Sciences of Limnology and Oceanography [20] [21] for her paper that introduced the concept of oxygen exposure time. [4]
In biogeochemistry, remineralisation refers to the breakdown or transformation of organic matter into its simplest inorganic forms. These transformations form a crucial link within ecosystems as they are responsible for liberating the energy stored in organic molecules and recycling matter within the system to be reused as nutrients by other organisms.
Cholestane is a saturated tetracyclic triterpene. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its derivatives and related chemical compounds in environmental samples is commonly interpreted as an indicator of animal life and/or traces of O2, as animals are known for exclusively producing cholesterol, and thus has been used to draw evolutionary relationships between ancient organisms of unknown phylogenetic origin and modern metazoan taxa. Cholesterol is made in low abundance by other organisms (e.g., rhodophytes, land plants), but because these other organisms produce a variety of sterols it cannot be used as a conclusive indicator of any one taxon. It is often found in analysis of organic compounds in petroleum.
A carbon-to-nitrogen ratio is a ratio of the mass of carbon to the mass of nitrogen in organic residues. It can, amongst other things, be used in analysing sediments and soil including soil organic matter and soil amendments such as compost.
Donald Eugene Canfield is an American geochemist and Professor of Ecology at the University of Southern Denmark known for his work on the evolution of Earth's atmosphere and oceans. The Canfield ocean, a sulfidic partially oxic ocean existing during the middle of the Proterozoic eon, is named after him.
In geochemistry, paleoclimatology, and paleoceanography δ13C is an isotopic signature, a measure of the ratio of the two stable isotopes of carbon—13C and 12C—reported in parts per thousand. The measure is also widely used in archaeology for the reconstruction of past diets, particularly to see if marine foods or certain types of plants were consumed.
Hypoxia refers to low oxygen conditions. Hypoxia is problematic for air-breathing organisms, yet it is essential for many anaerobic organisms. Hypoxia applies to many situations, but usually refers to the atmosphere and natural waters.
Isorenieratene /ˌaɪsoʊrəˈnɪərətiːn/ is a carotenoid light-harvesting pigment produced exclusively by the genus Chlorobium, which are the brown-colored strains of the family of green sulfur bacteria (Chlorobiaceae). Green sulfur bacteria are anaerobic photoautotrophic organisms, meaning they perform photosynthesis in the absence of oxygen using hydrogen sulfide in the following reaction:
The oceanic carbon cycle is composed of processes that exchange carbon between various pools within the ocean as well as between the atmosphere, Earth interior, and the seafloor. The carbon cycle is a result of many interacting forces across multiple time and space scales that circulates carbon around the planet, ensuring that carbon is available globally. The Oceanic carbon cycle is a central process to the global carbon cycle and contains both inorganic carbon and organic carbon. Part of the marine carbon cycle transforms carbon between non-living and living matter.
A whiting event is a phenomenon that occurs when a suspended cloud of fine-grained calcium carbonate precipitates in water bodies, typically during summer months, as a result of photosynthetic microbiological activity or sediment disturbance. The phenomenon gets its name from the white, chalky color it imbues to the water. These events have been shown to occur in temperate waters as well as tropical ones, and they can span for hundreds of meters. They can also occur in both marine and freshwater environments. The origin of whiting events is debated among the scientific community, and it is unclear if there is a single, specific cause. Generally, they are thought to result from either bottom sediment re-suspension or by increased activity of certain microscopic life such as phytoplankton. Because whiting events affect aquatic chemistry, physical properties, and carbon cycling, studying the mechanisms behind them holds scientific relevance in various ways.
Timothy Ian Eglinton is a British geologist who is a professor of biogeoscience at the Geological Institute, ETH Zürich.
Okenane, the diagenetic end product of okenone, is a biomarker for Chromatiaceae, the purple sulfur bacteria. These anoxygenic phototrophs use light for energy and sulfide as their electron donor and sulfur source. Discovery of okenane in marine sediments implies a past euxinic environment, where water columns were anoxic and sulfidic. This is potentially tremendously important for reconstructing past oceanic conditions, but so far okenane has only been identified in one Paleoproterozoic rock sample from Northern Australia.
Carbonate-associated sulfates (CAS) are sulfate species found in association with carbonate minerals, either as inclusions, adsorbed phases, or in distorted sites within the carbonate mineral lattice. It is derived primarily from dissolved sulfate in the solution from which the carbonate precipitates. In the ocean, the source of this sulfate is a combination of riverine and atmospheric inputs, as well as the products of marine hydrothermal reactions and biomass remineralisation. CAS is a common component of most carbonate rocks, having concentrations in the parts per thousand within biogenic carbonates and parts per million within abiogenic carbonates. Through its abundance and sulfur isotope composition, it provides a valuable record of the global sulfur cycle across time and space.
Microbial oxidation of sulfur is the oxidation of sulfur by microorganisms to build their structural components. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy to survive, grow and reproduce. Some inorganic forms of reduced sulfur, mainly sulfide (H2S/HS−) and elemental sulfur (S0), can be oxidized by chemolithotrophic sulfur-oxidizing prokaryotes, usually coupled to the reduction of oxygen (O2) or nitrate (NO3−). Anaerobic sulfur oxidizers include photolithoautotrophs that obtain their energy from sunlight, hydrogen from sulfide, and carbon from carbon dioxide (CO2).
An oxygen minimum zone (OMZ) is characterized as an oxygen-deficient layer in the world's oceans. Typically found between 200 m to 1500 m deep below regions of high productivity, such as the western coasts of continents. OMZs can be seasonal following the spring-summer upwelling season. Upwelling of nutrient-rich water leads to high productivity and labile organic matter, that is respired by heterotrophs as it sinks down the water column. High respiration rates deplete the oxygen in the water column to concentrations of 2 mg/L or less forming the OMZ. OMZs are expanding, with increasing ocean deoxygenation. Under these oxygen-starved conditions, energy is diverted from higher trophic levels to microbial communities that have evolved to use other biogeochemical species instead of oxygen, these species include nitrate, nitrite, sulphate etc. Several Bacteria and Archea have adapted to live in these environments by using these alternate chemical species and thrive. The most abundant phyla in OMZs are Pseudomonadota, Bacteroidota, Actinomycetota, and Planctomycetota.
Sulfur isotope biogeochemistry is the study of the distribution of sulfur isotopes in biological and geological materials. In addition to its common isotope, 32S, sulfur has three rare stable isotopes: 34S, 36S, and 33S. The distribution of these isotopes in the environment is controlled by many biochemical and physical processes, including biological metabolisms, mineral formation processes, and atmospheric chemistry. Measuring the abundance of sulfur stable isotopes in natural materials, like bacterial cultures, minerals, or seawater, can reveal information about these processes both in the modern environment and over Earth history.
Cindy Lee is a retired Distinguished Professor known for her research characterizing the compounds that comprise marine organic matter.
Margaret (Peggy) Delaney is marine geochemist known for her research on trace elements to examine changes in ocean chemistry over time.
Yan Zheng is a marine geochemist known for her research on metals in groundwater and private wells in Bangladesh, China, and the United States. She is an elected fellow of the Geological Society of America and the American Geophysical Union.
Elizabeth A. Canuel is a chemical oceanographer known for her work on organic carbon cycling in aquatic environments. She is the Chancellor Professor of Marine Science at the College of William & Mary and is an elected fellow of the Geochemical Society and the European Association of Geochemistry.
Maureen Hatcher Conte is biogeochemist known for her work using particles to define the long-term cycling of chemical compounds in seawater.
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