Bess Ward | |
|---|---|
| Alma mater | University of Washington (PhD, MS); Michigan State University (BS) |
| Known for | Biological oceanography, Biogeochemistry, Nitrogen cycle |
| Scientific career | |
| Fields | Oceanography, Biogeochemistry, Microbiology |
| Institutions | Princeton University |
| Thesis | Marine Ammonium-Oxidizing Bacteria: Abundance And Activity In The Northeast Pacific Ocean (1982) |
| Doctoral advisor | Mary Jane Perry |
| Doctoral students | Mary Voytek, Sarah Fawcett [1] |
Bess Ward is an American oceanographer, biogeochemist, microbiologist, and William J. Sinclair Professor of Geosciences at Princeton University. [2]
Ward studies include marine and global nitrogen cycles, and how marine organisms such as phytoplankton and bacteria influence the nitrogen cycle. Ward was the first woman awarded the G. Evelyn Hutchinson Award from the Association for the Sciences of Limnology and Oceanography (ASLO) for her pioneering work on applying molecular methods for nitrogen and methane conversions as well as scaling up organismal biogeochemical rates to whole ecosystem rates. [3]
Ward received her Bachelor of Sciences degree in zoology from the Michigan State University in 1976. Ward went on to obtain a Master's degree in biological oceanography from the University of Washington in 1979, followed by her PhD at the same institution in 1982. [4] Ward's early work focused on quantifying the rates of nitrogen transformation performed by bacteria and phytoplankton, and was the editor for a special edition of Marine Chemistry on "Aquatic Nitrogen Cycles" in 1985. [5]
After her PhD, Ward worked as a research biologist and oceanographer at the Scripps Institution of Oceanography in San Diego, California, where she also served as the chairperson of the Food Chain Research Group. [4]
Ward became a professor of Marine Sciences at the University of California, Santa Cruz in 1989. From 1995–1998, Ward was the Chair of the Ocean Sciences Department at University of California, Santa Cruz before becoming a professor in the Department of Geosciences at Princeton University in 1998. In 2006, Ward became the Chair of the Department of Geosciences at Princeton and has held the position ever since. Ward has held numerous visiting scientist and trustee positions throughout her career at institutions such as the Bermuda Institute of Ocean Sciences, Plymouth Marine Laboratory, and the Max Planck Institute für Limnologie. As of 2018, Ward had advised 21 graduate students and 20 postdoctoral scholars. Broadly, Ward and her lab members research how bacteria and phytoplankton transform and use nitrogen in marine and coastal ecosystems using various molecular and isotopic techniques. [6] [7] [8] Ward spends time on research cruises and expeditions, conducting research (and sometimes teaching remotely [9] ) while on the ocean for days to weeks at a time.
Areas in the ocean that are low in oxygen, called oxygen deficient zones (ODZs), are important areas for nitrogen cycling yet only make up about 0.1-0.2% of the total volume of the world ocean. Over one quarter of all nitrogen in the oceans is lost to gaseous nitrogen forms (e.g. N2, N2O) in the ODZs through various nitrogen transformation pathways including denitrification and anammox, however, the rates of nitrogen transformation and type of transformation that is taking place in ODZs remains unclear and subject of much of Ward's research. [10] [11] [12] [13] Ward and her lab developed an isotopic tracer method to measure the rate of N2O reduction in the Eastern Tropical North Pacific Ocean and found that incomplete denitrification in ODZs increases N2O accumulation and eventual efflux to the atmosphere. [7] N2O is a potent greenhouse gas and Ward's research shows that the expanding ODZs in the global ocean may increase the amount of N2O entering the atmosphere.
Ward has served on review panels of university graduate programs, institutional oceanography programs, and National Science Foundation funding programs. [4]
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmospheric nitrogen, making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.
Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms or entirely within one organism, as in comammox bacteria. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea.
Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denitrification as a type of respiration that reduces oxidized forms of nitrogen in response to the oxidation of an electron donor such as organic matter. The preferred nitrogen electron acceptors in order of most to least thermodynamically favorable include nitrate (NO3−), nitrite (NO2−), nitric oxide (NO), nitrous oxide (N2O) finally resulting in the production of dinitrogen (N2) completing the nitrogen cycle. Denitrifying microbes require a very low oxygen concentration of less than 10%, as well as organic C for energy. Since denitrification can remove NO3−, reducing its leaching to groundwater, it can be strategically used to treat sewage or animal residues of high nitrogen content. Denitrification can leak N2O, which is an ozone-depleting substance and a greenhouse gas that can have a considerable influence on global warming.
Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. Denitrification is performed by a variety of denitrifying bacteria that are widely distributed in soils and sediments and that use oxidized nitrogen compounds such as nitrate and nitrite in the absence of oxygen as a terminal electron acceptor. They metabolize nitrogenous compounds using various enzymes, including nitrate reductase (NAR), nitrite reductase (NIR), nitric oxide reductase (NOR) and nitrous oxide reductase (NOS), turning nitrogen oxides back to nitrogen gas or nitrous oxide.
In enzymology, a nitrous oxide reductase also known as nitrogen:acceptor oxidoreductase (N2O-forming) is an enzyme that catalyzes the final step in bacterial denitrification, the reduction of nitrous oxide to dinitrogen.
Farooq Azam is a researcher in the field of marine microbiology. He is a distinguished professor at the Scripps Institution of Oceanography of the University of California, San Diego. Farooq Azam grew up in Lahore and received his early education in Lahore. He attended University of Punjab, where he received his B.Sc. in chemistry. He later he received his M.Sc. from the same institution. He then went to Czechoslovakia for higher studies. He received his PhD in microbiology from the Czechoslovak Academy of Sciences. After he received his PhD, Farooq Azam moved to California. Azam was the lead author on the paper which coined the term microbial loop. This 1983 paper involved a synthesis between a number of leaders in the (then) young field of microbial ecology, specifically, Azam, Tom Fenchel, J Field, J Gray, L Meyer-Reil and Tron Frede Thingstad.
The G. Evelyn Hutchinson Award is an award granted annually by the Association for the Sciences of Limnology and Oceanography to a mid-career scientist for work accomplished during the preceding 5–10 years for excellence in any aspect of limnology or oceanography. The award is named in honor of the ecologist and limnologist G. Evelyn Hutchinson. Hutchinson requested that recipients of the award have made considerable contributions to knowledge, and that their future work promise a continuing legacy of scientific excellence.
Bacterioplankton refers to the bacterial component of the plankton that drifts in the water column. The name comes from the Ancient Greek word πλαγκτός (planktós), meaning "wandering" or "drifting", and bacterium, a Latin term coined in the 19th century by Christian Gottfried Ehrenberg. They are found in both seawater and fresh water.
Paul G. Falkowski is an American biological oceanographer in the Institute of Marine and Coastal Sciences at Rutgers University in New Brunswick, New Jersey. His research work focuses on phytoplankton and primary production, and his wider interests include evolution, paleoecology, photosynthesis, biogeochemical cycles and astrobiology.
Aerobic denitrification, or co-respiration, the simultaneous use of both oxygen (O2) and nitrate (NO−3) as oxidizing agents, performed by various genera of microorganisms. This process differs from anaerobic denitrification not only in its insensitivity to the presence of oxygen, but also in its higher potential to form nitrous oxide (N2O) as a byproduct.
Dr. Syed Wajih Ahmad Naqvi is an Indian marine scientist and the former director of the National Institute of Oceanography. His work has concentrated in oceanic water chemistry, biogeochemistry, and chemical interrelations with living organisms. He has also performed research on freshwater ecosystems. He was the chief Indian scientist of LOHAFEX, an ocean iron fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany.
Urine patches in cattle pastures generate large concentrations of the greenhouse gas nitrous oxide through nitrification and denitrification processes in urine-contaminated soils. Over the past few decades, the cattle population has increased more rapidly than the human population. Between the years 2000 and 2050, the cattle population is expected to increase from 1.5 billion to 2.6 billion. When large populations of cattle are packed into pastures, excessive amounts of urine soak into soils. This increases the rate at which nitrification and denitrification occur and produce nitrous oxide. Currently, nitrous oxide is one of the single most important ozone-depleting emissions and is expected to remain the largest throughout the 21st century.
Dissimilatory nitrate reduction to ammonium (DNRA), also known as nitrate/nitrite ammonification, is the result of anaerobic respiration by chemoorganoheterotrophic microbes using nitrate (NO3−) as an electron acceptor for respiration. In anaerobic conditions microbes which undertake DNRA oxidise organic matter and use nitrate (rather than oxygen) as an electron acceptor, reducing it to nitrite, and then to ammonium (NO3− → NO2− → NH4+).
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.
The viral shunt is a mechanism that prevents marine microbial particulate organic matter (POM) from migrating up trophic levels by recycling them into dissolved organic matter (DOM), which can be readily taken up by microorganisms. The DOM recycled by the viral shunt pathway is comparable to the amount generated by the other main sources of marine DOM.
Sybil P. Seitzinger is an oceanographer and climate scientist at the Pacific Institute for Climate Solutions. She is known for her research into climate change and elemental cycling, especially nitrogen biogeochemistry.
Yvette Hardman Edmondson was the editor of Limnology and Oceanography the premier journal of the Association for the Sciences of Limnology and Oceanography and was an aquatic scientist known for her research on bacteria in aquatic systems.
Curtis A. Suttle is a Canadian microbiologist and oceanographer who is a faculty member at the University of British Columbia. Suttle is a Distinguished University Professor who holds appointments in Earth & Ocean Sciences, Botany, Microbiology & Immunology and the Institute for the Oceans and Fisheries and a Fellow of the Royal Society of Canada. On 29 December, 2021 he was named to the Order of Canada. His research is focused on the ecology of viruses in marine systems as well as other natural environments.
Susanne Menden-Deuer is an oceanographer and marine scientist known for her work on marine food webs, including their structure and function. As of 2022, she is president-elect of the Association for the Sciences of Limnology and Oceanography.
Helle Ploug is marine scientist known for her work on particles in seawater. She is a professor at the University of Gothenburg, and was named a fellow of the Association for the Sciences of Limnology and Oceanography in 2017.
| Authority control databases: Academics |
|---|
