Plenary speakers

Dr. Serban Danielescu is an Environment and Climate Change Canada research scientist based at Agriculture and Agri-Food Canada’s Fredericton Research and Development Centre (Fredericton, New Brunswick, Canada). Dr. Danielescu obtained the Ph.D. degree from the University of New Brunswick, Canada (Department of Engineering) and previously received M.Sc. and a Ph.D. degrees from the University of Bucharest, Romania (Department of Systems Ecology and Sustainable Development). His research focuses on understanding the impact of agricultural practices on groundwater quantity and quality and on downgradient aquatic ecosystems. In recent years, Dr. Danielescu has also been involved in development of online hydrology tools and models for encouraging open science (Hydrology Tool Set; https://www.hydrotools.tech/). Through a collaborative research program, Dr. Danielescu employs various field investigation methods in combination with a wide range of modelling approaches to develop an integrated perspective on the transfer of water and contaminants from sources to receiving waters. His research contributed to advancing knowledge on topics such as transport and fate of agriculturally-sourced nitrogen in the subsurface; modelling of soil-plant-water systems; role of wetlands in attenuating nitrogen fluxes; impact of intensive agricultural practices on eutrophication of coastal waters; impact of climate change on hydrological processes and contaminant fluxes; assessment of water quantity and quality at local and watershed scale; residence time of water in the subsurface (i.e.; groundwater age dating); influence of septic systems on lake water quality; use of phreatophytes (e.g.; willows) for hydraulic control of landfill-impacted groundwater.

EXCESS NITROGEN IN THE ENVIRONMENT: AGRICULTURAL SOURCES, TRANSPORT AND ATTENUATION
Serban Danielescu
Research Scientist, Environment and Climate Change Canada and Agriculture and Agri-Food Canada, Fredericton, New Brunswick, Canada

Abstract
Excess nitrogen associated with intensive agricultural practices has been linked to potential negative environmental impacts. Thus, agriculture is the largest source of anthropogenic nitrous oxide (N2O), a potent greenhouse gas (GHG). In the subsurface, nitrogen can be present in several forms, with nitrate (NO3-) and ammonium (NH4+) being the predominant inorganic forms of nitrogen in soil. Nitrate is highly mobile and has an increased potential for leaching below the soil layer. Unless attenuated via denitrification or other mechanisms (e.g.; plant uptake) nitrate can travel to both groundwater and downgradient aquatic ecosystems. Excessive nitrate loading can result in increased health risks when groundwater is used as a source of drinking water and can also lead to deterioration of the quality of downgradient aquatic ecosystems when transported to surface waters (e.g.; algal blooms, anoxic waters). In this context, Dr. Danielescu will present an overview of the nitrogen cycle, highlight the linkages between agriculture and excess nitrogen in the environment, and will discuss on-site (e.g.; Beneficial Management Practices) and off-site (e.g.; natural and artificial wetlands) solutions for attenuation of nitrogen fluxes. The presentation will be enhanced with examples of studies from across the world, with a particular focus on research he conducted in North America and Eastern Europe.