Thought Leader Webinar Series
Tersus Environmental offers a comprehensive suite of training opportunities. The Thought Leaders Webinar Series highlights the latest ideas for in situ remediation from our industry's leading thinkers. These webinars will connect you directly with these leaders so you can learn new techniques and strategies to boost your knowledge, benefit your bottom line, and serve your clients better. All webinars are taught by people who really know in situ remediation and are eager to share their knowledge with you.
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Nitrogen in the subsurface: an overview of the linkages between intensive agriculture and groundwater quality, Dr. Serban Danielescu, Research Scientist, Environment and Climate Change Canada and Agriculture and Agri-Food Canada
Date and Time: Thu, Jun 15, 2017 1:00 PM - 2:00 PM EDT
Registration URL: https://attendee.gotowebinar.com/register/2181744811987346434
Abstract: Nitrogen from agricultural sources has been linked to potential negative impacts on groundwater quality and on downgradient aquatic ecosystems. In many parts of the world, including North America, agricultural practices constitute a significant source of nitrogen for both the unsaturated zone and groundwater. Nitrogen is a primary macronutrient required for plants, and hence, is often added during crop growth to supplement the nitrogen naturally available in soils. In the subsurface, nitrogen can be present in several interconvertible forms. Most nitrogen in soils is found in organic form, and it can become available to plants once is converted to inorganic nitrogen. Ammonium (NH4+) and nitrate (NO3-) are the predominant inorganic forms of nitrogen in soil, with NO3- being highly mobile and thus having an increased potential for leaching below the soil layer. With a few exceptions (e.g. waste disposal sites) where NH4+ may predominate, NO3- is the most common form of inorganic nitrogen found below the soil zone. Unless removed via denitrification, NO3- travels through the unsaturated zone and aquifer(s) and can be discharged into downgradient aquatic ecosystems. Excessive NO3- loading to groundwater can result in increased health risks when groundwater is used as a source of drinking water and can lead to hypertrophication (e.g. algal blooms potentially resulting in anoxic events) of the downgradient aquatic ecosystems.
The presentation will include an overview of the theoretical background of nitrogen cycle in the subsurface, and will include examples of investigations conducted in agriculture dominated areas in Atlantic Canada. The examples will cover processes occurring in the unsaturated zone (root/soil zone and deeper vadose zone) as well as in the aquifer, and will extend from inland to coastal areas. Examples of the methods employed to understand the spatial and temporal trends of nitrogen in the subsurface, include thermal infrared imaging, use of stable isotopes (water, nitrate), resistivity monitoring of tracer plumes, models of nitrogen cycling in soil and of transport and fate of nitrogen in the unsaturated and saturated zones at field and watershed scales, as well as a study of hydraulic control of contaminated shallow groundwater using phreatophytes.
Bio: Dr. Serban Danielescu is a research scientist jointly appointed with Environment and Climate Change Canada (ECCC) and Agriculture and Agri-Food Canada (AAFC) and located at AAFC’s Fredericton Research and Development Centre in (the province of) New Brunswick, Canada. Dr. Danielescu started his current appointment after receiving his Ph.D. from the University of New Brunswick (Department of Engineering) in 2009. He previously received a M.Sc. (1999) and a Ph.D. (2007) from the University of Bucharest (Romania) while conducting research at the Department of Systems Ecology and Sustainable Development. Dr. Serban Danielescu’s research is focused on understanding the impact of agricultural practices on groundwater quantity and quality, as well as on downgradient aquatic ecosystems. As part of his research, he employs conventional groundwater field investigation methods in conjunction with various modelling approaches, to develop an integrated ecosystem-based perspective on the transfer of water and contaminants from sources to receiving surface water bodies at various spatial and temporal scales.
Development and Testing of an Analytical Method for Real Time Measurement of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS), Dr. Rula Deeb, Geosyntec Consultants / Dr. Andy Eaton, Eurofins Eaton Analytical
Date and Time: Resheduled; new date coming soon.
Registration URL: Comming soon.
Rula Deeb, Ph.D., BCEEM, PMP
Andy Eaton, PhD, BCES
Perfluoroalkyl and polyfluoroalkyl and substances (PFAS), including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), were released to the environment at many federal and commercial facilities in the United States and elsewhere as a result of historical uses of aqueous film-forming foams (AFFF) to extinguish fuel-based fires. Due to the strength of their carbon-fluorine bonds, PFAS are persistent in the environment and difficult to remediate. Because a suite of these compounds has recently been the focus of regulatory attention, there is a growing need to characterize PFAS at groundwater impacted sites. Characterization data are needed to inform site-specific risk assessments and to guide the selection of appropriate remedial action/management approaches. The past decade of industry experience at hydrocarbon and chlorinated solvent sites has demonstrated that real time and high resolution site characterization is faster, more cost-effective and more sustainable compared with more traditional methods from a lifecycle perspective.
Current analytical methods for PFAS are fixed-lab based, expensive and require long turn-around times. The goal of this project is to develop a mobile unit capable of analyzing samples in real time in the field at a fraction of the cost required by a fixed laboratory. This technology is based on a published but relatively unknown analytical method. This presentation will describe the development and testing of a prototype mobile unit capable of analyzing PFAS samples in real time in the field.
The development of the method was based on refining and adapting an existing analytical method for the analysis of PFOA and PFOS. The testing phase was performed on samples collected from Cape Canaveral (Florida) and Barksdale Air Force Base (Louisiana). The results of the comparison of the analytical results using the real time analytical method with results using EPA methods are promising. This work is important for several reasons: (1) many AFFF-impacted sites have little to no existing monitoring wells and the extent of contamination is often unknown; (2) traditional approaches to install and sample wells using current analytical methods require a long turnaround time to receive the data; and, (3) this mobile unit, when deployed with DPT sampling, would facilitate rapid, high resolution characterization. Ongoing efforts to refine the method to reach lower detection limits and to expand the suite of PFAS that are detectable using the real-time measurement method will also be discussed.