Postdoctoral Research Collaborations and Projects (current and previous):

• 2016 – 2018 – Layered double hydroxide (LDH) precipitation kinetics (rates) in soils and mineral systems. Surface precipitation of LDHs enhances heavy and trace metal (Ni, Zn, Co) sequestration in contaminated soils – effectively inhibiting heavy metal contaminant mobility. LDHs in general have many other industrial, medical, and energy uses. I study LDHs using advanced synchrotron-based techniques.

 

• 2016 – 2017 – Wavelet transformation of nickel-aluminum (Ni-Al) LDHs. Ni-Al LDHs form in soils contaminated with Ni under various conditions and sequester (inhibit) further metal release into the environment. Wavelet transformation of synchrotron-base X-ray absorption spectroscopic data (XAS) can help identify and characterize Ni-Al LDH.

 

• 2016 – 2018 – Determining the chemical forms (species) of nickel (Ni) in serpentine soils. Ni is a trace metal present in contaminated soils and occurs geogenically in serpentine soils. Ni hyperaccumulating plants are native to serpentine soils and remove Ni from the soil. They can be used in natural attenuation remediation strategies, phytoremediation, and agromining.

 

• 2016 – 2018 – Precipitation kinetics and formation of iron-aluminum (Fe-Al) LDHs. Fe precipitation and dissolution are a critical part of the global Fe biogeochemical cycle. Fe-Al LDHs are part of that cycle and naturally occur and mineral precipitates and intermediate phases in saturated soils and sediments. They are a related compound to green rusts. (Lead student: A. Betts)

 

• 2016 – 2018 – Speciation of legacy phosphorous (P) in Delmarva soils. Soil P and cycling of P on the Delmarva Peninsula impacts nutrient runoff into the Chesapeake and Delaware Bays and estuaries. We analyze the chemical forms (species) of P in the soils to improve predictions of P loss and sequestration. (Lead student: K. Szerlag)

 

• 2016 – 2018 – Arsenic redox reactions with iron oxides under salinity and redox gradients. Climate change and sea level rise impact contaminated soils in flood-prone areas and costal coastal regions. It is critical to understand how contaminants such as arsenic, chromium, and organic contaminants in these soils will behave and be released upon saturation and disturbance in significant storm events (Lead student: J. Sanchez)

 

• 2015 – 2016 – Ferrous iron (Fe2+) oxidation kinetics by iron oxidizing bacteria. I employed both electrochemical (cyclic voltammetry) and spectroscopic (UV-Vis) methods to determine the rates of biotic ferrous iron oxidation. Iron oxidizing bacteria are commonly found in fresh and saltwater environments and impact Fe cycling in the environment.

 

• 2015 – 2016 – Fabricate solid-state mercury amalgam electrodes for detection of low concentration dissolved oxygen using voltammetry. Determine the most suitable electrodes gold or silver electrodes for detecting dissolved oxygen down to ca 500 nanomolar concentrations. Dissolved oxygen is a critical variable in oxic and suboxic waters. It dictates what biogeochemical reactions can occur; thus it is critical to effectively (and affordably) measure dissolved oxygen.

 

• 2014 – 2015 – Perform research on oxygen consumption kinetics during biogenic manganese oxide formation using cyclic voltammetry. Dissolved manganese and oxygen concentrations were measured in situ to determine oxygen consumption and manganese oxidation rates. Biogenic manganese oxides are a dominant form of manganese oxides in the environment and are powerful heavy metal scavengers and oxidants.

 

• 2014 – 2016 – Determine chemical forms (speciation) via voltammetry of trace elements and metals in sediment porewaters from the St. Lawrence Estuary, Québec, Canada and from the Chesapeake Bay, MD. This work required two separate field research cruises (7+ days each), where I employed electrochemistry (cyclic voltammetry) using microelectrodes to study iron, manganese, sulfide and dissolved oxygen in sediment porewaters on board.

 

• 2014 – 2015 – Reduction kinetics of polymeric manganese(IV) oxide with iron(II). Employ UV-Vis spectroscopy to measure the rates of MnO2 loss via Fe oxidation. The Mn and Fe redox cycles overlap in saturated soils and sediments, and they are critical elements for many forms of terrestrial and aquatic life. This is an important cycle in both local and global geochemical cycling of Fe and Mn.