Diane M. McKnight
The 2015 John Dalton Medal is awarded to Diane M. McKnight for seminal contributions to understanding the interactions of hydrology, biogeochemistry and ecology of lakes and streams, and the interaction of surface water and groundwater.
Diane McKnight’s work has displayed a stunning record of scientific innovation. She has built a solid theoretical foundation on the interactions between natural organic matter (NOM) and metals, and leveraged this towards a productive set of research activities grounded in field observations. She developed a 30-year stream-water chemistry record, paired with hydrologic data, in the Rocky Mountains in Colorado, and a similar 20-year dataset in McMurdo Dry Valley (Antarctica). The data collected in these sites has revealed that dissolved organic matter found in streams was primarily derived from microbial processes as opposed to plant matter breakdown. They indicated a significant increase in summer low-flow metal concentrations in a period of melting permafrost and falling water tables. Through these studies she has demonstrated the importance of coupling of physical hydrology and biological processes, e.g., that patch-scale variations in bed shear stress and flow intermittency (i.e., diel flood pulses) control the NOM release from microbial streambed mats. Her work has helped the hydrology and limnology communities to understand the important role that NOM plays in everything from regulating metal redox reactions to catalysing the photodegradation of persistent organic pollutants. She has been instrumental in developing fluorescence spectrosocopy to identify the origins of dissolved NOM and its redox status, thus opening the door to new ways to study NOM-metal interactions.
Through sustained research undertaken over 30 years Diane McKnight has helped to establish the biogeosciences as a major interdisciplinary field. She helped found the Biogeosciences Section within the American Geophysical Union, and was a founding editor of the Journal of Geophysical Research –Biogeosciences. She currently serves as the President of the American Society of Limnology and Oceanography. Through her leadership efforts she has helped merge the more physically oriented Earth science community with the biological and ecological scientific communities, having organised large interdisciplinary teams.
McKnight’s academic career is most interesting and adventurous. She has pursued highly multidisciplinary research backed up by data collected in some of the toughest environments the planet has to offer (from the South Pole to deep in Africa). Hers is the kind of interdisciplinary research that modern hydrologists are seeking – she has contributed to a broadening of the foundations of hydrologic science. She does not stop at scientific publications aimed at peers: her publications include two children’s books, The Lost Seal, and My Water Comes from the Mountains. She serves as an inspirational role model for children and young women.
In conclusion, for seminal contributions to understanding the interactions of hydrology, biogeochemistry, and ecology of lakes and streams, for unselfish leadership of the field of biogeosciences, and for serving as an inspiration to many young scientists, Diane McKnight is awarded the John Dalton Medal of the EGU.