Trace Metal Biogeochemistry Laboratory

elements under microscope

Welcome to the Twining Laboratory! We conduct interdisciplinary research on the biogeochemistry of metals in marine and aquatic systems. Our research is focused on the interactions between trace metals and aquatic organisms that have biogeochemical, ecological, or toxicological implications. Our work takes many forms and includes laboratory investigations with cultured phytoplankton and protists, as well as fieldwork to collect and study planktonic organisms in natural systems. Our work can be organized into a few themes:

Elemental composition of plankton

Planktonic organisms influence the distribution and geochemical fate of many important elements (including carbon) in the ocean by accumulating these elements into their cells. We strive to understand the factors that affect element stoichiometries in marine protists. Plankton also form the base of most aquatic food webs, and contaminants such as cadmium, selenium, silver, and mercury can become concentrated in plankton and passed to higher organisms. We are interested in the determining the occurrence and understanding the implications of metal accumulation in marine organisms. Much of our recent work has been funded as part of the international GEOTRACES program.

Elemental composition of macroalgae

There is growing interest in commercial harvesting and aquaculture of seaweeds for use as human food and feed supplement for livestock. We are involved in several projects to understand the elemental composition of seaweeds, including the USDA-funded Coast-Cow-Consumer project. This work involves measuring arsenic (including inorganic and organic species), iodine, and major ions such as magnesium, calcium, and potassium, in addition to our favorite trace elements, in seaweed and cow milk, urine, and manure.

Micronutrient limitation and cycling

Phytoplankton growth in several large ocean regions is limited by the availability of iron and potentially cobalt, manganese, and even zinc. Some of our work is specifically focused on understanding trace metal cycling and biogeochemistry. We have been involved in projects investigating metal limitation and cycling in the equatorial Pacific Ocean, Indian Ocean, Southern Ocean, Arctic Ocean, Weddell Sea, Sargasso Sea, and in coastal waters off New Zealand, California, and British Columbia. We find that shipboard incubations help to keep our backs strong! We often use synchrotron x-ray fluorescence (SXRF) to study metal accumulation by phytoplankton, as well as inductively coupled plasma mass spectrometry, radioisotope tracers, chemiluminescence, and electrochemical techniques to determine trace metal concentrations and speciation.

Ocean Iron Fertilization

As atmospheric carbon dioxide has risen past the level safe for the Earth’s long-term climate stability, it has become clear that we will eventually need to remove gigatons of atmospheric carbon dioxide through a process called carbon dioxide removal (CDR). This can only be effective after human CO2 emissions are significantly reduced, but emissions reduction alone won’t be enough. The oceans will likely play an important role in CDR, and ocean iron fertilization (OIF) is one of the approaches being considered. We are involved in ExOIS, a group of experts working to establish best practices and governance for the study of ocean iron fertilization. We have also collaborated on several recent papers exploring the possibilities, and possible limitations, of OIF. Given the urgent need to develop CDR approaches that minimize negative environmental consequences, we are working to envision next generation field studies that can be used to test and inform modeling work.

Twining group members

We have been lucky to have many talented folks spend time working in our group over the years:

Past members

  • Kristin Rouse – University of South Carolina undergraduate student
  • Elyse Walker – University of South Carolina undergraduate student
  • Kaitlin Duffey – University of South Carolina undergraduate student
  • Allison Dalbec – University of South Carolina masters student
  • Brandon Bozard – University of South Carolina masters student
  • Daliangelis Nunez-Milland – University of South Carolina masters student
  • Hai Lin – University of South Carolina PhD student
  • Hannah McDaniel – Bigelow Laboratory REU intern
  • Maria Nielsdottir – visiting postdoctoral researcher
  • Meaghan Daley – Bigelow Laboratory REU intern
  • Brittney Honisch – Bigelow Laboratory REU intern
  • Conor Maginn – Bates College undergraduate intern
  • Angel Ruacho – Bigelow Laboratory REU intern
  • Jochen Nuester – Bigelow Laboratory postdoctoral researcher
  • Kaitlyn Pritchard – Bigelow Laboratory REU intern
  • Alice Chapman – Bigelow Laboratory REU intern
  • Jeremy Jacquot – Bigelow Laboratory postdoctoral researcher
  • Jade Enright – Bigelow Laboratory REU intern
  • Brooke Stemple – Bigelow Laboratory REU intern
  • Sarabeth George – Bigelow Laboratory REU intern and Sea Change Semester intern
  • Dan Ohnemus – Bigelow Laboratory postdoctoral researcher
  • Renee Torrie – Bigelow Laboratory REU intern
  • Liz Mann – Bigelow Laboratory postdoctoral researcher
  • Erika Alvarado – Bigelow Laboratory REU intern
  • Gabriela Kim – Bigelow Laboratory REU intern and Sea Change Semester intern
  • Dylan Halbeisen – Bigelow Laboratory REU intern
  • Owen Keleher – Bigelow Laboratory REU intern
  • Wilson Stecher – Bigelow Laboratory REU intern
  • Silas Gramaglia – Bigelow Laboratory REU intern
  • Jeb Wennrich – Bigelow Laboratory REU intern
  • Sara Rauschenberg – Bigelow Laboratory senior research associate
  • Katherine Bowen – Bigelow Laboratory REU intern
  • Alex Burt – Bigelow Laboratory REU intern

Current members

  • Laura Sofen – Bigelow Laboratory postdoctoral researcher
  • Jarret Mayo – Bigelow Laboratory research technician