Dissolved organic matter in freshwaters: nature, origins and ecological significance

William H McDowell is Professor of Environmental Science in the Department of Natural Resources and the Environment at the University of New Hampshire in Durham, USA.  He has a background in ecosystem ecology and has worked on land-water interactions for over 40 years.  He published some of the earliest descriptions of the origin and controls on dissolved organic matter in streams and continues to study organic matter dynamics with a wide range of techniques including in situ optical sensors. Dr McDowell is former Chairperson of the Department of Natural Resources, serves as Director of the NH Water Resources Research Center, and currently holds a UNH Presidential Chair.  He is co-chair of the US International LTER Committee.  McDowell teaches courses on watershed management and ecosystem ecology.  He is author of over 250 publications on biogeochemistry and has been cited in peer-reviewed articles over 18,000 times.  He conducts long-term research in New Hampshire, Czech, and Puerto Rican watersheds, with a focus on understanding the interactions between nutrients and dissolved organic matter and linking critical zone structure to biotic processes. He has served as PI of the Luquillo Critical Zone Observatory since 2013.  

Professor Chris Evans works on carbon cycling in aquatic and terrestrial ecosystems, with a particular focus on peatlands, greenhouse gases and the role of aquatic carbon fluxes in the global carbon cycle. His field-based research extends from the high latitudes to the tropics, and covers a range of temporal and spatial scales, ecosystems, scientific questions and policy issues. He is currently the CEH co-lead for the NERC LOCATE project on land-ocean carbon cycling, which aims to improve understanding of the processing and fate of terrestrially-derived organic matter along the freshwater-marine continuum. Chris was a Lead Author of Flooded Lands chapter of the 2019 IPCC Agriculture, Forestry and Other Land-Use Guidelines refinement, and the 2013 IPCC Wetland Supplement, for which he helped to develop methods to incorporate CO2 and CH4 emissions from ditches, rivers, ponds and reservoirs in national greenhouse gas emissions inventories. He is a visiting professor at the Swedish University of Agricultural Sciences, where he previously held the position of King Carl XVI Gustaf’s 20th Visiting Professor in Environmental Science for his work on aquatic carbon cycling.

Hans W Paerl is the Kenan Professor of Marine and Environmental Sciences at the University of North Carolina’s Institute of Marine Sciences. His research addresses microbially-mediated nutrient/carbon cycling and primary production dynamics, environmental controls and management of harmful algal blooms, and assessing effects of human and climatic alterations of biogeochemical cycling, water quality and sustainability of inland, estuarine and coastal marine waters. He has published over 300 peer reviewed articles and book chapters on these subjects. He received the 2003 G. Evelyn Hutchinson Award from the Association of the Sciences of Limnology and Oceanography, and the 2011 Odum Award from the Coastal and Estuarine Research Federation for addressing the causes, consequences and controls of eutrophication in aquatic ecosystems. In 2015, he was named a Fellow of the American Geophysical Union.

Dr Emily S Bernhardt is the James B Duke Professor of biogeochemistry in Duke’s Department of Biology. Dr Bernhardt’s research is motivated by a desire to understand how our use of watersheds alters energy and nutrient cycling in receiving streams and wetlands and the extent to which management efforts can reverse, ameliorate or improve aquatic ecosystem structure and function. Dr. Bernhardt has been recognized for her scholarly productivity and impact with the 2004 HG Hynes Award from the Society for Freshwater Science; the 2013 Yentsch-Schindler award from the Association for the Sciences of Limnology and Oceanography; the 2015 Mercer Award from the Ecological Society of America; and a 2015 Friedrich Wilhelm Bessel Research  Award from the Alexander von Humboldt Foundation. She is a Leopold Leadership Fellow and a Fellow of the Ecological Society of America.

Timothy Eglinton FRS is Professor of Biogeoscience within the Department of Earth Sciences at ETH Zürich. Eglinton obtained a BSc in Environmental Science at the Plymouth Polytechnic, and MSc and PhD in Organic Geochemistry at the University of Newcastle-upon-Tyne.  Following postdoctoral research positions at Delft Technical University (Netherlands) and Oslo University (Norway), he joined Woods Hole Oceanographic Institution in 1989. He was a member of the Scientific Staff there until 2010, when he joined ETH. Eglinton’s research program is centered on tracing the origin, cycling and legacy of biospheric carbon on planet Earth, and to understand the role of organic matter production, remineralization, transport and burial as a component of the global carbon cycle. He focusses on processes on the continents and in the oceans, as well as the transfer of carbon between these systems. He has pioneered radiocarbon measurements at the molecular level as a tool to examine carbon cycle processes.   More information is available at: http://www.biogeoscience.ethz.ch/.

Liz Minor is a full professor in the Department of Chemistry and Biochemistry and at the Large Lakes Observatory at the University of Minnesota Duluth, USA.  She received her B.S. in Chemistry from The College of William and Mary in Virginia (Williamsburg, VA, USA) and her Ph.D. in Marine Chemistry and Geochemistry from the MIT/WHOI Joint Program in Oceanography and Ocean Engineering (Woods Hole, MA, USA).  She did post-doctoral work in macromolecular mass spectrometry at FOM-AMOLF (Amsterdam, The Netherlands). Her research group studies carbon cycling in lake, river, and ocean water columns across seasonal to decadal scales.  As part of this work, they apply spectroscopy and mass spectrometry approaches to characterize the molecular and isotopic composition of aquatic organic matter components. Minor is the author/co-author of 54 papers on carbon cycling in aquatic systems (with 21 of these focused upon studying large lakes systems). 

Charlotte Lloyd obtained her PhD in Geography from the University of Bristol in 2012, researching the transport of livestock-derived organic matter through hillslopes, using a molecular approach. She then completed post-doctoral work at the University of Bristol as part of the Defra funded Hampshire Avon Demonstration Test Catchment project, where she developed numerical analytical methods for interrogating high temporal resolution water quality data. She moved to the School of Chemistry at the University of Bristol in 2014 in order to join the NERC funded DOMAINE programme where she has developed laboratory analytical methods for the molecular characterisation of dissolved organic matter in freshwater systems. Her work combines molecular chemistry with hydrology in order to enhance our understanding of the impact of organic compounds in the environment.

Thorsten Dittmar is professor for Marine Geochemistry and director of the Institute for Chemistry and Biology of the Marine Environment (ICBM) at the University of Oldenburg. He studied geoecology and marine chemistry (Universities of Bayreuth and Bremen, Germany). Before he was appointed professor in Oldenburg, he was a group leader at the Max Planck Institute (MPI) for Marine Microbiology in Bremen and professor for Chemical Oceanography at Florida State University (USA). He also worked several years at universities in Belém (Brazil) and Seattle (USA). Dittmar’s research focus is the organic geochemistry of the oceanic water column. Most of the organic matter in the ocean resides there in dissolved form, and the oceans are among the largest organic carbon pools on Earth’s surface. Dittmar introduced novel ultrahigh-resolution mass spectrometry techniques in the marine sciences to address long-standing open questions in the oceanic carbon cycle.

Davey Jones holds a joint Professorship in Soil & Environmental Science between Bangor University, UK and the University of Western Australia. His research focuses on nutrient cycling in terrestrial ecosystems with emphasis on soil-plant-microbial interactions and understanding the links between land and water in relation to nutrients and human pathogens. He was Co-I on the NERC DOMAINE project and PI on the NERC VIRAQUA project looking at carbon cycling and microbiological quality in freshwater and marine systems. He advises Welsh Government and Defra on climate change and land use policy. He has published over 420 ISI journal articles on aspects of soil, water and atmospheric science.

Chris gained his PhD from the University of Reading in 2014, researching the use of fluorescence spectroscopy to characterise dissolved organic matter across a range of UK freshwater ecosystems. Later that year he joined the NERC-DOMAINE programme where his work focussed on using a combination of laboratory experiments and in-stream sensor technologies to investigate how landscape scale processes drive changes in instream dissolved organic matter composition. Chris is currently working on the NERC funded PISCES project, investigating the impact of Patagonian ice field shrinkage on coastal and fjord ecosystems, with a focus on the changing export of nutrients.

Dr Kellerman's research interests revolve around dissolved organic matter, its sources, sinks and factors that control its degradation and persistence. She is interested in a variety of aspects of organic matter biogeochemistry: the detailed characterization of chemical composition and controls thereof, the link between chemical composition and reactivity, the importance of intrinsic and extrinsic controls on organic matter persistence and reactivity, and the pathways that protect organic matter from microbial degradation. She is also interested in how the methods we use to characterize organic matter influence our interpretation of how it exists in situ. Such methods include absorbance and fluorescence spectroscopy, size exclusion chromatography, and ultrahigh resolution mass spectrometry. Her research questions often pertain to the effects anthropogenic activities have on organic matter characteristics, such as how land-use and climate change affect dissolved organic matter composition. Her biogeochemical interests have spread from lakes to a variety of aquatic ecosystem and soils.

Research in my laboratory aims to understand the fate of organic matter released from terrestrial systems into freshwater and marine systems. In order to understand these complex dynamics, we employ advanced organic matter characterization techniques in areas that are difficult to reach and work in, but critical to study. In this quest to better understand anthropogenic impacts on the global carbon cycle, we have undertaken diverse studies ranging from examining the fate of organic carbon released from glacial melting and permafrost thawing, to assessing the impacts of pristine land conversion on carbon export in watersheds like the Congo and Amazon. 

Pat Glibert is a Professor at the University of Maryland Center for Environmental Science (UMCES), Horn Point Laboratory.  She received her Ph.D. from Harvard University and was a Postdoctoral Scholar and an Assistant Scientist at the Woods Hole Oceanographic before moving to the University of Maryland. Dr. Glibert also holds an Honorary Doctorate from Linnaeus University, Sweden, and is a Fellow of the American Association for the Advancement of Science. Pat’s research centers around questions related to nutrient dynamics, particularly the effects of eutrophication, and algal blooms. Her current work is focused on the linkages between changes in the amounts and forms of nutrient loading, harmful algal blooms (HABs), and changes in aquatic food web structure.

Lars Tranvik received a PhD in limnology from Lund University, Sweden, in 1990. He is a professor at Uppsala University, Sweden. His research has developed from aquatic microbial ecology, in particular the role of heterotrophic bacteria in food webs and as consumers of dissolved organic matter, to a broader focus on the carbon cycle of inland waters. Recent research is focused on how terrestrial organic matter is transformed in the water column resulting in a subsidy to aquatic food webs, a sediment carbon sink, and emission of carbon dioxide and methane to the atmosphere. Currently, he shares his time between research and teaching at the Limnology program, and being head of the Department of Ecology and Genetics.

Dr Mackay is a freshwater nutrient ecologist with 11 years of experience in research on multiple aspects of lake and freshwater ecology. Her research interests include elucidating the role of algae within biogeochemical cycles, particularly in relation to the nutrients phosphorus and nitrogen. She utilises a range of different approaches in her work including the analysis of long term and high frequency monitoring data, statistical and process-based modelling and laboratory experiments. As part of the DOMAINE project, she has been involved in experiments to investigate the availability of organic nitrogen and phosphorus compounds to stream algae (phytoplankton, epilithon) and higher plants. Examining the controls on the bioavailability of organic nutrients across different habitats over time.

Tom Battin is still excited by studying the ecology of microbial biofilms and their involvement in biogeochemical cycles in streams. His laboratory combines extensive fieldwork with experimental work and modelling to understand and predict coupled physical, chemical and biological processes in stream ecosystems. Lately his laboratory has become involved in the study of glacier-fed streams and their microbiome around the world. He received his PhD from the University of Vienna where he was Chair in Limnology. Currently he is Professor at the Ecole Polytechnique Fédérale de Lausanne.