Chad R. Hammerschmidt, Ph.D.
Associate Professor

Department of Earth & Environmental Sciences
272B Brehm Lab
Wright State University
3640 Colonel Glenn Highway
Dayton, OH 45435

E-mail:
Office phone: (937) 775-3457
Dept phone: (937) 775-2201
Dept fax: (937) 775-4997

Courses Taught

Fall Semester

• EES 4240/6240 Oceanography, 3 Hrs
• EES 4310/6310 Standard Methods of Biogeochemical Analysis, 2 Hrs [Jointly Taught]

Spring Semester

• EES 4590/6590 Advanced Aquatic Geochemistry, 3 Hrs [Odd Years]
• EES 4510/6510 Effective Scientific Communication, 3 Hrs [Even Years]

Research

Dr. Hammerschmidt earned a Ph.D. in oceanography from the University of Connecticut in 2005, and was a Postdoctoral Scholar at the Woods Hole Oceanographic Institution prior to joining Wright State University as an assistant professor in September 2007.  His research is focused on developing a quantitative understanding of the biological, chemical, and physical mechanisms and processes that affect the transport, transformation, and fate of mercury and other trace metals in the environment.  His recent and on-going studies are examining the biogeochemistry of mercury and methylmercury in arctic and temperate watersheds, marine systems (coastal and open ocean), and the atmosphere.

On-going major research projects include the following:

1. GEOTRACES Intercalibration of Collection, Handling and Analysis Methods for Mercury Species in Seawater (Supported by NSF-Ocean Sciences).  Collaborative project with Carl Lamborg (Woods Hole Oceanographic Institution), Rob Mason (University of Connecticut), and Gary Gill (Pacific Northwest National Laboratory).  August 2008−August 2010.

This collaborative project is testing old ways and developing new methods to ensure that oceanographic mercury (Hg) data is of the highest quality.   Accurate measurements of total mercury and mercury species in seawater are challenging because concentrations are very low and potential sources of contamination are ubiquitous and can be ruinous.  Total Hg is commonly about 1 picomolar (~ 200 parts per quadrillion) in the mixed layer of the ocean and individual species, such as methylmercury and dimethylmercury, are much less.  This means that we need to collect and analyze samples with sensitive equipment and methods that do not contaminate the samples.  Our four research laboratories are vetting methods used commonly to collect, handle, and analyze samples for Hg species in seawater ahead of the U.S. GEOTRACES oceanographic cruises that will begin in 2010.  This study has included laboratory testing of methods, intercalibration with other Hg researchers worldwide, and participation in the 2008 intercalibration cruise in the North Atlantic (WHOI and UConn) and the 2009 intercalibration cruise between Honolulu and San Diego in the North Pacific (Wright State and PNNL).  This work is important because it will ensure that results from different research groups are accurate and therefore useful for broadening our knowledge of the cycling of this toxic element in the ocean.

2. Vertical and Horizontal Distributions of Mercury Species in the South Atlantic Ocean (Supported by NSF-Ocean Sciences [to Lamborg] and Wright State University).  Collaborative project with Carl Lamborg (Woods Hole Oceanographic Institution).  November 2007−present.

There is limited knowledge of the distribution of mercury species in the ocean.  This research is examining the longitudinal and vertical distributions of mercury species along a transect of the South Atlantic Ocean, based on a 30-day, trans-Atlantic cruise that we took aboard the R/V Knorr from Fortaleza, Brazil, to Walvis Bay, Namibia, in late 2007 (Mak Saito, chief scientist).  The primary goal of the cruise was to determine the distribution and speciation of several trace metals that influence the productivity and health of the ocean, namely iron, cobalt, zinc, cadmium, and mercury.  The cruise track included coastal, gyre, and upwelling regions of the South Atlantic, with seawater collected for Hg analysis from about 10 stations spanning the western and eastern basins (vertical profiles to 5000 m), as well as additional stations near the Benguela Current (western Africa), which results in upwelling of deep ocean water and associated potential changes in the speciation, transformation (e.g., methylation of Hg), and biological uptake of dissolved metals.  We are currently analyzing the ~400 water samples that were collected during the cruise.

Stations in the South Atlantic Ocean where seawater was sampled for Hg analysis in November–December 2007.

3. Mercury Biogeochemistry on the Continental Shelf and Slope (Supported by NSF-Ocean Sciences).  Collaborative study with Bill Fitzgerald (University of Connecticut).  May 2008−April 2012.

Methylmercury is the form of mercury (Hg) that bioaccumulates and biomagnifies in marine food webs, especially piscivorous fish, and represents the primary human health concern related to mercury in the environment.  Most fish consumed by humans are of marine origin, and the coastal zone, including biologically productive upwelling regions, is the major source of marine fish productivity.  Unfortunately, little is known about the sources and cycling of methylmercury in marine systems, especially the important continental shelf regions.  Benthic Hg methylation on the continental shelf and slope is a potentially significant contributor of methylmercury to the marine environment, including biota and the open ocean.  Thus, and given the limited information and knowledge regarding Hg distributions and biogeochemistry in shelf sediments and waters, we are conducting a three-year investigation that is focused on processes and reactions affecting the cycling of methylmercury in sediments and waters over a broad region of the shelf and slope of the northwestern Atlantic Ocean.   This study includes sampling of multiple environmental matrixes for analysis of Hg and mercury species (methylmercury, dimethylmercury, elemental Hg):  water, suspended particles, sediment, sediment pore fluids, and zooplankton.  This descriptive component is complemented by mechanistic studies that are examining 1) factors affecting the sediment-water exchange of methylmercury, 2) the identity of microorganisms that produce and demethylate methylmercury in sediments, 3) bioaccumulation of methylmercury in planktonic food webs, 4) geochemical factors affecting net production of methylmercury in sediments, and 5) photochemical reactions that demethylate mercury and result in it being less available for uptake by organisms.  These measurements and experiments are focused around three 11-day oceanographic cruises (one each in 2008, 2009, and 2010) in the northwest Atlantic Ocean that have provided a platform for student research and involvement.  On the 2009 cruise, for example, nine of the 13 science party members were students.

Wright State students have produced real-time blogs of their at-sea experiences and science:

I. August 2008 cruise:  http://atlanticcruise08.blogspot.com/

II. Sept–Oct 2009 cruise: http://atlanticcruise09.blogspot.com/

III. August 2011 cruise: http://atlanticcruise2010.blogspot.com/

Completed (red line, Fall 2010) and proposed GEOTRACES cruise tracks (Fall 2011) in the North Atlantic Ocean. Information on the GEOTRACES program can be found at www.geotraces.org.

5. Field verification of factors controlling nickel bioavailability in sediments (Supported by Nickel Producers Environmental Research Association).  Collaborative project with Allen Burton (University of Michigan).  March 2009–March 2010.

This project complements an on-going laboratory study, being conducted by Chris Ingersoll’s group at the U.S. Geological Survey in Columbia, Missouri, that is testing the toxicity of sedimentary nickel (Ni) to a suite of aquatic organisms.  The laboratory investigation employs Ni-amended sediments that have a broad and contrasting range of physicochemical characteristics that are suspected to influence the bioavailability of Ni, namely iron oxyhydroxides, acid-voltile sulfides, and organic matter.  Here, Burton and Hammerschmidt are extending the laboratory results to “real-world” conditions in field.  Our research involves the in situ geochemistry and toxicity of Ni to benthic macroinvertebrates in caged exposures.  The outcome of this work will be development of new models that better predict the bioavailability of Ni to aquatic organisms and thereby help protect ecosystem quality.

6. Effects of alum on benthic communities and trace metal and nutrient cycling in Grad Lake St. Mary’s, Ohio (Supported by Ohio Water Resources Research Institute).  Collaborative study with Amy Burgin (Univ. of Kansas) and Geraldine Nogaro (Grand Valley St., Mich.).  January 2011–January 2012.

Grand Lake St. Mary’s is a large (50 km2) lake in western Ohio that has become eutrophied by current and historical loadings of nutrients, largely from cropland runoff (manure).  Excessive loadings of phosphorous have resulted in blooms of cyanobacteria that produce harmful toxins and reduce the recreational capacity of the lake and its aesthetic beauty.  In an attempt to improve water quality, the State of Ohio treated about 2/3 of the lake in summer 2011 with alum (aluminum sulfate; $3.5 million of it), which was intended to complex phosphorous and reduce the bioavailability to cyanobacteria.  The objective of our on-going study is to investigate the potential unintended consequences of such a broad-scale “environmental experiment” on benthic invertebrate communities and the cycles of important nutrients and trace metals.

Dr. Hammerschmidt is currently advising several students:

• Deepthi Nelluri, BS Candidate (2013).
• James Detraz, MS Candiadte (2012)
• Joel Harvey, MS Candiadte (2012)
• Sarah Harvey, MS Candiadte (2014)
• Jaclyn Klaus, MS Candiadte (2014)
• Kelsey Danner, MS Candiadte (2014)
• Rebecca Gamby, MS Candiadte (2014)
• Katlin Bowman, PhD Student (started Summer 2012)
• Dan Marsh, PhD Student (started Summer 2012)