ROBERT J. ROSSI
Research Interests
My research focuses on metal dynamics in urban soils. In particular, I am interested in processes that mobilize the increased trace metal loadings that result from industrial or vehicular emissions. I am also interested in how the hydrology in urban areas affect patterns in soil moisture, and subsequently can increase the mobility of toxic trace metals (e.g., lead, arsenic) and other pollutants common to urbanized areas.
To examine these topics I combine geospatial data (e.g., road network coverage, historical aerial imagery), field soil/sediment/water chemistry data, and field soil moisture measurements. The combination of Geographic Information System, hydrological, and chemical analyses allows for characterization of cation mobilization processes in urban systems. Understanding these processes is essential to the effective management of watersheds and ecosystems, as urban areas continue to expand and therefore affect increased numbers of ecosystems.
Research Projects
Quantifying the Volume of Anaerobic Microsites in Upland Soils
Soils are one of the largest dynamic stocks of carbon on earth, and as such, are a critical component of the global carbon cycle. The availability of oxygen for microbial respiration exerts a fundamental control on CO2 and CH4 efflux in terrestrial ecosystems that is largely overlooked in upland soils which are commonly considered to be well aerated in terrestrial ecosystem models. However, recent work has shown that anaerobic microsites, which exist due to the complex physical structure of soils, can also exert a fundamental control on mineralization rates in upland soils. This research will provide a framework to estimate soil anaerobic pore volumes from easily scalable soil parameters (e.g., texture, moisture content), thus refining the predictive abilities of global soil carbon models.
Project Status: Ongoing
Funding Sources: The Nature Conservancy
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Upland soils
Influence of Legacy Sewer Infrastructure on Urban Groundwater Patterns
Infiltration based stormwater control measures are a common strategy utilized to control runoff in urban areas. However, historical urbanization practices can create heterogeneities in subsurface flow regimes leading to unexpected patterns in the water table surface, which in turn, can decrease the efficiency of infiltration based stormwater management strategies. This research examined water level data between February 2016 and May 2017 in monitoring wells installed along the US I-95 corridor in Philadelphia, PA. Analysis of these data provided information on baseline groundwater conditions near recently installed stormwater control measures. Furthermore, this analysis highlighted the influence of a legacy sewer line on subsurface flow regimes, suggesting that historic sewer infrastructure has the potential to cause unexpected patterns of groundwater inundation due to changes in global sea level.
Project Status: Complete
Funding Sources: Pennsylvania Department of Transportation, AECOM
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Bioretention basin storing water during a rainstorm
Reconstructing Historical Phosphorus Loadings to Urban Soils
Throughout the twentieth century increased phosphorous cycling has made eutrophication in surface waters commonplace. While agricultural phosphorus sources are well characterized, the role of legacy phosphorus pools in modern phosphorus cycles is relatively less constrained. This research reconstructs historical loadings of phosphorus to urban soils in Southern California and Pittsburgh, Pennsylvania. Furthermore, this research utilizes an R-based model to understand almost a century of phosphorus and arsenic biogeochemical cycles in Pittsburgh, PA soils.
Project Status: Ongoing
Funding Sources: University of Pittsburgh Dietrich School of Arts and Sciences
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Agal bloom, image credit Ohio Sea Grant
Reconstructing Historical Trace Metal Loadings in Pittsburgh, PA
Although the Southwestern PA region, in particular Pittsburgh, PA, was the cradle of fossil fuel based industrialization in the US, the history of the environmental impacts of this industrialization are very poorly documented. Pittsburgh had a variety of industries including iron manufacturing, steel production, and secondary lead smelting, among others. This research will reconstruct a lake sediment record of trace metal inputs to a remnant of the Pennsylvania Canal located slightly northwest of the City of Pittsburgh.
Project Status: Ongoing
Funding Sources: University of Pittsburgh Dietrich School of Arts and Sciences
Industry in early 20th century Pittsburgh
Reconstructing Legacy Trace Metal Contamination
The remobilization of legacy contamination stored in floodplain sediments remains a threat to ecosystem and human health, particularly with potential changes to global hydrological cycles. Vehicular and industrial emissions are often the dominant recognized source of anthropogenic trace metal loadings to ecosystems today. However, loadings from early industrial activities are poorly characterized and can rival modern trace metal inputs. This research reconstructed a lake sediment record of trace metal inputs from a lake in Southwestern PA, documenting the impact of early industry in the Southwestern PA region, as well as early industrial coal production/consumption on legacy trace metal contamination.
Project Status: Complete
Funding Sources: University of Pittsburgh Dietrich School of Arts and Sciences, the University of Pittsburgh Andrew Mellon Predoctoral Fellowship, and the University of Pittsburgh Department of Geology and Planetary Science Henry Leighton Memorial Fellowship
Preparing to core Markle Lake
Impacts of Road Salt Application on Roadside Soil Metal Dynamics
Road salt is applied to roadways in high latitudes to improve traffic conditions in winter weather. However, the dissolution of road salt in highway runoff creates waters with high total dissolved solids (TDS), which can mobilize soil metals via soil cation exchange reactions. Between 2013 and 2014, soil water samples were collected from a transect of lysimeter nests perpendicular to I-376 in Pittsburgh, PA. The analysis of metal concentrations in these samples were used to examine soil cation dynamics. A deeper understanding of these processes is necessary to effectively restore and manage watersheds as high TDS solutions (i.e., road deicing, hydraulic fracturing, and marginal irrigation water) increasingly influence ecosystem function.
Project Status: Ongoing
Funding Sources: University of Pittsburgh Dietrich School of Arts and Sciences, the University of Pittsburgh Department of Geology and Planetary Science Henry Leighton Memorial Fellowship, and the Heinz Foundation
Collecting samples from suction cup lysmeters
Soil Acidification in Los Angeles Roadside Soils
Roadside soils are heavily loaded with reactive nitrogen due to vehicular emissions, and these loadings likely acidify near-road soils. This project characterized relationships between soil metal concentrations and relevant road network (e.g., density, proximity) and spatial characteristics (e.g., distance from ocean, annual precipitation) in surficial soil samples collected within Los Angeles metropolitan area.
Project Status: Complete
Funding Sources: University of Pittsburgh Dietrich School of Arts and Sciences, the University of Pittsburgh Office of Experimental Learning, the Heinz Foundation, University of California--Riverside, and the National Science Foundation