Catholic Mission

Professor Diz, undergraduate students Matt Drury, Buck Neely, Ross Hollenbeck, Wes Willow

It has been known by microbiologist for decades that many microorganisms produce hydrogen gas as a normal part of their metabolism. Normally, the hydrogen produced is immediately converted to other products such as methane by other bacteria.  As a result, bacterial production of hydrogen has not yet been shown to be a practical method to produce this valuable gas.

This project is developing the technology necessary to avoid conversion to methane.  Thus far, anaerobic bioreactors in the laboratory have been producing hydrogen gas for more than ten months without any methane generation.  Factors to optimize the system design are now being studied, and a pilot-scale system is planned for the near future at a food processing factory on the outskirts of Erie.

Evaluation of the Extent and Transport Capabilities of Atmospheric Polycyclic Aromatic Hydrocarbons in the Lake Erie Watershed
Professors: Homan and Tallmadge, MS students Jay Dahl and Chris Saber

The department conducted a study under contract with the US Army Corps of Engineers to develop a computer model of Mill Creek and Cascade Creek in Erie, PA, for predicting hydrology and sediment transport.  Automated stormwater monitoring and sampling equipment was installed near the mouths of Cascade Creek and Mill Creek and on Mill Creek above the "Mill Creek Tube", which is a large storm sewer through which the stream flows in its lower portion.  The watershed is largely urbanized in the lower area, but mostly undeveloped or residential in the upper reaches.  GIS software linked to state-of-the-art hydrodynamic computer models was used to model the watershed to predict discharge and the transport of sediment.  The model (SWAT: Soil and Water Assessment Tool) is driven by land use, soil type, and climatic factors, and can be used to illustrate hypothetical scenarios relating to land use decisions and non-point source pollution management practices.

This is an on-going series of investigations to better understand the distribution, origin, and effects of high levels of arsenic in the sediments of Presque Isle ponds  by Dr. Diz and his students.

A study of the occurrence of arsenic in pond sediments on the Presque Isle peninsula, Erie, PA, was initiated due to concerns expressed by citizens and due to occasionally high arsenic results in samples collected for other purposes by various government officials.  Samples of pond and lagoon sediments were collected at thirteen primary sites and additional reference sites during the fall, 2000, and again in spring, 2001.  The probable effect concentration (PEC) for arsenic of 33.0 mg/kg was exceeded in the surface  sediments at all 13 interior sites during fall testing.  It was exceeded in all but one site during spring testing.   For deep sediments, the PEC was exceeded in the fall at 9 sites and in the spring at 6 sites.   Arsenic concentrations for fall sampling ranged from 36.9 mg/kg to 325.4 mg/kg for surface sediments and from 8.3 mg/kg to 206.3 mg/kg for deep sediments.  Spring 2001 sampling revealed arsenic ranges from 17.5 mg/kg to 393.6 mg/kg for surface  sediments and 3.6 mg/kg to 327.3 mg/kg for deep sediments. 
Read the final report in PDF format.
 

Microbes have been identified which are involved in the change in oxidation state of arsenic in Presque Isle pond sediments.  These microbes use tri-valent arsenic (arsenite) as a terminal electron acceptor in deep anaerobic sediments and so convert it to penta-valent arsenic (arsenate).  This is an important process to document and quantify because arsenite is much more soluble than is arsenate.  Arsenate tends to precipitate with iron and sorb to organic matter, thus removing it from solution and making it less mobile.  This may be an important part of the mechanism described below which has led to an enrichment of arsenic in Presque Isle pond sediments.  Work is on-going to quantify the rate at which this biogeochemical transformation is occurring, and how it fits into an overall mass balance for arsenic in this ecosystem.
 

Benthic macroinvertebrates are to be collected from selected Presque Isle ponds to determine if elevated levels of arsenic in the pond sediments have an adverse effect on the benthic community structure.  The composition of the benthic community is often used as an indicator of environmental quality, since certain benthic organisms are very sensitive to oxygen stress and chemical pollutants.  The benthic macro-invertebrate community plays an important role in the food web in any aquatic ecosystem, and is the source of food for scavenging higher organisms such as bottom-dwelling fish and birds. 
 

A possible natural mechanism for the unusually high levels of arsenic in Presque Isle pond sediments is hypothesized.  The sandy Presque Isle peninsula is surrounded by Lake Erie and Presque Isle Bay, and the interior ponds on the peninsula are hydraulically connected to the Lake and Bay by groundwater.  The proposed mechanism suggests that natural fluctuations in Lake and Bay levels cause a pulsing of groundwater through the sandy soil of the Presque Isle peninsula into the land-locked ponds, transporting dissolved reduced arsenic, which occurs naturally in the shale bedrock of the area.  It is postulated that dissolved arsenic is forced up through organic and iron-rich sediments of the ponds; once in the ponds, the arsenic is oxidized and is precipitated and/or sorbed to the oxic surface layer of the sediments.  Over the approximately 5,000 years since the formation of the peninsula, it is hypothesized that this mechanism has resulted in the high levels of arsenic now observed in the present-day sediments.  A laboratory apparatus was constructed to contain a column of sediments from the ponds, and expose the sediment to an accelerated version of the hypothesized natural mechanism.  Results are not yet available.

As part of a comprehensive watershed study funded by the Growing Greener program (PA DEP), the habitat and physicochemical assessment of the Pennsylvania streams which flow into Lake Erie will include a description of land use patterns and measurements of instream parameters such as width, depth, flow, and bed substrate.  Water quality parameters which will be evaluated include in situ measurements of temperature, conductivity, dissolved oxygen, and turbidity.  In addition, water samples will be collected for suspended solids determination and chemical analysis for selected contaminants of concern. 
Final Report