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Tuesday, November 7th
4:00 PM

Wake Up Barren Soil! Improving Enzymatic Function of Contaminated Soils

Nina M. Goodey, Montclair State University

A legacy of industrial use in metropolitan areas has left many soils contaminated with heavy metals and organic compounds. In some impacted soils, contaminants have altered the soils’ properties and ability to function. Soil microorganisms exude enzymes that break down nutrients, helping to nourish microorganisms and plants. Productive soils are often characterized by high enzymatic activities that are needed to convert decaying matter to plant nutrients. In soils where enzymatic function is low or nonexistent, plants may lack nutrients and fail to thrive. This case-study focuses on such a site within Liberty State Park in Jersey City, NJ, a brownfield that was once a railyard built on landfill from development in New York City. Our work is aimed at understanding why differently contaminated areas within the park have varying levels of enzymatic function. One application of this work is to discover processes to enhance soil biochemical function, to convert contaminated soils to productive and functional environments, and to increase enzyme function in contaminated, poorly functioning soils.

4:00 PM - 5:00 PM

Tuesday, November 14th
4:00 PM

Challenges to Managing Sewage Pollution in Estuaries: Insights from Emerging Monitoring Tools and Investigation of Microbial Exchange Among Water, Sediment and Air

Gregory O’Mullan, CUNY Queens College

In recent decades, focused environmental management and re-investment in wastewater treatment infrastructure have resulted in significant improvements to water quality of the Hudson River Estuary and the connected waterways of New York City. However, urban stormwater, Combined Sewer Overflow (CSO), incomplete sewage treatment, and wildlife remain as sources of allochthonous bacteria, oxygen consuming waste, and other emerging contaminants. Once delivered to the waterway pollutants are transported within the estuary and exchange can occur among sediment, water, and adjacent air masses. Using data from microbial cultivation, high throughput DNA sequencing, geochemical assays, and environmental sensors this seminar will address patterns in common water quality indicators, pollution source identification, as well as the distribution and exchange processes influencing sewage pollutants, with a particular emphasis on fecal bacteria. The data will be discussed in the context of current management challenges and planned sewage pollution mitigation activities.

4:00 PM - 5:00 PM

Tuesday, November 28th
4:00 PM

Creepy Landscapes and Critical Points: How Rivers and Hillslopes Behave like Glass

Doug Jerolmack, University of Pennsylvania

Soil on hillslopes slowly and imperceptibly creeps downhill, but suddenly liquefies to produce landslides. The transition between creeping and flowing is a critical point, often defined in terms of the shear stress, that depends on the characteristics of the soil and the geologic environment. We show that the nature of this transition, however, is general. Creep is the localized and erratic motion of soil grains below the critical point; because this kind of fragility is a generic consequence of disorder (no minimum energy state can be achieved because there is no crystal), soil creep should be similar to amorphous glass. Indeed, we find that the transition from creeping to landsliding is a continuous phase transition that follows predictions from glass transition models. The generality of this transition suggests that the onset of sediment transport in rivers should behave in a similar manner, and we demonstrate that this is the case using laboratory experiments and simulations. Because the sediment transport rate rapidly increases for stresses above critical, many landscapes such as rivers organize to be close to the critical point. In essence, landscapes flicker back and forth across the glass transition. We show that this critical behavior has consequences for how landscapes respond to external forcings such as climate. In particular, self-organization of near-critical river channels filters the climate signal evident in discharge, blunting the impact of extreme rainfall events on landscape evolution.

4:00 PM - 5:00 PM

Tuesday, December 12th
4:00 PM

Exploiting Synchrotron “Light” to Study Chemistry of Trace Elements in Soils and Plants

Ryan Tappero, Brookhaven National Laboratory

Biogeochemical studies often require characterization of elemental abundances and speciation in samples that are chemically and physically heterogeneous at the micrometer scale. Synchrotron radiation sources are ideal for developing high intensity, highly-focused X-ray probes for interrogating the speciation, transport, and reactions of trace elements in heterogeneous earth and biological materials with detection sensitivities in the attogram range and spatial resolutions less than 1 micrometer.

X-ray Fluorescence Microprobe (XFM) is a new, multi-modal X-ray fluorescence microscope recently installed at the National Synchrotron Light Source-II (NSLS-II) at Brookhaven National Laboratory. XFM has capabilities for X- ray micro-fluorescence (μ-XRF) imaging and tomography, X-ray absorption spectroscopy (μ-XAS), and X-ray microdiffraction (μ-XRD). Micro-XRF allows one to image and quantify the distribution of trace elements in heterogeneous samples. Micro-XAS analysis allows one to interrogate oxidation state and chemical speciation of the trace elements. Coupled XRF-, XAS-, XRD- microanalysis allows one to quantify the abundance and speciation of elements at trace concentrations and evaluate the mineralogy to which they are adsorbed or bound in soil. Such information is crucial in understanding the toxicity, mobility and containment of toxic metals in the environment and the mechanisms of nutrient uptake and partitioning in plants. Examples will be given of how these instruments are applied in the Plant and Soil Sciences.

4:00 PM - 5:00 PM