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Research Focus
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The ecohydrology group laragely focuses on interactions between hydrological and ecological systems. However, our research projects cover a broad range of topics that often take us somewhat outside of this focus area. The ultimate goal of most of our work is to develop better strategies for protecting water quality and the "natural" environment. Two themes that we are currently building projects around are:
understanding the interactions between hydrology & biogeochemical hotspots
and
applying nanotechnology to hydrological systems
Our research projects tend to be fluid, with one leading naturally to another and often taking us in unexpected directions. Thus, it is difficult to keep track of all the individual efforts. Below are descriptions of a few broad research areas that capture much of our work but are by no means comprehensive.
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Environmental Nanotechnology
Key-Collborator:
Dr. Dan Luo
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Applying the power of nanoscale technology to answer landscape-scale questions constitutes an exciting new frontier in science and engineering. We are currently exploring one possible method of reducing the "nonpoint" problem associated with nonpoint source (NPS) pollution, i.e., the problem of locating from where in the landscape water pollution originates. Specifically, we are developing technologies for identifying and characterizing different flowpaths at field and watershed scales by labeling or coding them with unique DNA-based nanobarcodes, of which there are essentially limitless combinations, i.e., lots of flowpaths can be uniquely coded. Our ultimate vision is to have the capacity of introducing our micro- or nano-tracers at different points in a watershed, collecting them "downstream" in the watershed, and using quantitative techniques to the hydrological linkages and transport times between the collection point(s) and the points of tracer introduction. The potential advantages of this nanotechnology strategy compared to conventional tracers are the elimination of background interferences and the ability to segregate superimposed flowpaths through the design of strictly unique nano-tracers.
Current activities include: 1) experimenting with different materials (e.g., PLGA and chitonase) to encapsulate the DNA-lable, 2) developing strategies for capturing nano-tracers moving in a hydrological pathway, and 3) experimenting with the nano-tracers in different hydrological systems, e.g., vadose zone, urban runoff, etc.
Watch a USDA CSREES Video about some of our environmental nanotechnology research
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There is good evidence that parts of the landscape that are prone to saturation constitute biogeochemical “hotspots,” i.e., areas where reaction rates are disproportionately high relative to the surrounding environment. We are focusing largely hydrological controls on phosphorus and nitrogen processes in the landscape.
For nitrogen we are using combinations of isotopic, chamber, and micrometeorology methods to quantify denitrification at different points in the landscape and at different spatiotemporal scales. We hope that this information will help us "map" denitrification hotspots and develop agricultural strategies for reducing nitrogen loads to streams and rivers.
Phosphorus mobility in soil remains largely mysterious. We ahve a suite of projects characterizing, quanitifying, and modeling phosphorus mobility and transport. Recently we have turned to microbiological methods to locate and quanitify microbial populations and species that may impose important controls on how mobile phosphorus is. One class of microbe that appears especially interesting is "phosphorus accumulataing organism" or PAO, which has been widely studied in the context of waste water treatment (enhanced biological phosphorus reduction), but has only recently been identified in soils.
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Transport in Runoff
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Storm runoff is an important vector for pollutants and other materials. Our work considers both the whatershed-scale hydrological processes that control runoff generation and the "raindrop-scale" processes involved in entraining and transporting material in runoff. This research area is shared across the the Cornell Soil and Water Lab.
Much of our runoff generation research focuses on measureing, modeling, and predicting variable source areas (VSAs), i.e., areas in the landscape that are prone to getting wet-enough to generate rapid latteral flow, or storm runoff. The Soil and Water Lab has a legacy of VSA runoff research including the famous Dunne and Black (1970) papers in Water Resources Research (Dick Black was a former memeber of the Soil and Water Lab). we have developed a wide range of watershed hydrology models for predicting where, when, and how much runoff is generated and we have coupled these with different methods for predicting loads. One new project area is considering the roles of ditches and other human modifications to the landscape's natural drainage system on pollutant transport.
Our pollutant entrainment research uses small-scale experiments and analytical modeling to describe how solutes, sediment, microorganisms, and other materials are transported from the landscape surface into surface runoff and subsequently moved down-slope. We have looked at these processes with both soil or an urban (e.g., pavement) surfaces.
One new direction we are taking this work is to predict runoff and nonpoint source pollution generation by incorporating radar and other remote-sensing technologies. We are also developing cost-effective field monitoring networks to track landscape moisture conditions to make real-time and forecast predictions of where storm runoff will likely occur.
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Phosphorus Index
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We have several activities like this one that bring together information from a variety of our basic-research projects to develop real applications for helping protect the environemnt. The phosphorus index (P-Index) is a tool that has been adopted by several states to help manage the land-application of fertilizers, animal manures, and other phosphorus-rich materials. In New York State, the P-Index combines two components: a source component that indicates how phosphorus-rich a part of the landscape is and a transport component that indicates how prone a part of the landscape is to generating runoff and transporting material to a stream. Although the current transport component is based on our VSA runoff work, we have made a variety of scientific breakthroughs that improve our ability to effectively predict where runoff will be generated.
Our current activities are multifaceted. For example, we are testing various runoff-predicting methods on past situations where polluted runoff was a problem in order to determine the best methods for predicting phosphorus pollution risks. At the same time we are characterizing the runoff potential for all the gaged watersheds in New York State in order to make our predictions more ubiquitously applicable. We have also developed a web-based tool for easy point-and-click use by practitioners.
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ACKNOWLEDGEMENTS
Dr. J.-Yves Parlange, Dr. Tammo S. Steenhuis, & the Rain Machine...
Friends, mentors, and colleagues to whom I'm forever indebted.
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