RESEARCH

Our research investigates how biogeochemical processes affect the fate, transport and food-web bioaccumulation of trace metals and organic chemicals in aquatic ecosystems. Our applied goal is to characterize how changes in climate and emissions affect human and ecological health, and the potential impacts of regulatory actions. Our research integrates understanding of the physical/chemical properties of contaminants with the biogeochemistry of natural ecosystems and human/ecological exposure pathways.

FIELD/LABORATORY RESEARCH

BIOGEOCHEMICAL MODELS

RISK ASSESSMENT

Our field and lab research focuses on understanding relationships between environmental properties (e.g., DOC, temperature, productivity) and chemical speciation/bioavailabilty of trace metals and organic compounds. We measure reaction rates and concentrations in environmental samples that can be used to parameterize and evaluate our modeling simulations. We are ramping up our in-house analytical capacity to measure a suite of contaminants using HPLC-MS/MS and ICP-MS.

We use environmental models to investigate the broader spatial and temporal implications of relationships measured in the field and to synthesize multi-disciplinary research. Our models vary in complexity from relatively simple geochemical box models to advanced 3-D simulations of atmospheric (GEOS-Chem) and ocean circulation (MITgcm, FVCOM) driven by assimilated meteorological data. We are also developing models for bioaccumulation of contaminants in marine food webs.

We use food-frequency questionnaires (FFQs) and probabilistic exposure simulations integrated with pharmacokinetic (PK) models to estimate human exposures to contaminants. We also measure human biomarkers of exposure (hair, blood). We work closely with environmental epidemiologists looking at dose-response relationships to quantify present risks and link this information with environmental models to help anticipate public health impacts of climate change and regulations.

- OVERVIEW OF CURRENT PROJECTS -

Biogeochemical Modeling

Lab/Field Based Projects

Risk Assessment

Background:

 

Our work is developing and evaluating global simulations for compounds of interest in the oceans within the MITgcm with ecology (Darwin model). We are using these simulations to better understand the relationship between global production of these chemicals and accumulation in food-web and ultimately human exposure. We use the GEOS-Chem model to simulate atmpospheric inputs to aquatic and terrestrial systems.

 

 

 

 

Ongoing Projects and People:

 

  • Improved oxidation chemistry for Hg species in the atmosphere in the GEOS-Chem model (Hannah Horowitz)
  • Global budget for MeHg in the oceans and influence of climate (Yanxu Zhang, Amina Schartup)
  • Temporal trends in air-sea exchange of PCBs (Charlotte Wagner)
  • PFAS cycling in the global oceans (Xianming Zhang, Charlotte Wagner)
  • Global terrestrial cycling of Hg species in the CASA model (Rebecca Stern)
  • Global methane releases from hydroelectric reservoirs (Bram Maasakkers, Ryan Calder, Melissa Sulprizio)
  • Global model for MeHg bioaccumulation and impacts on in fish (Amina Scartup, Colin Thackray, Miling Li)
  • Food web modeling of MeHg bioaccumulation in marine ecosystems (Amina Schartup)
  • Influence of climate variability on MeHg bioaccumulation in a Subarctic estuary (Ryan Calder)

 

Collaborators: Stephanie Dutkiewicz (MIT), Rainer Lohmann (URI), Daniel Jacob (Harvard)

 

Support: NSF Office of Polar Programs, UBC Nereus Project, Harvard Climate Change Solutions Fund , Nunatsiavut Government

 

Background:

We are interested in the global biogeochemical cycles of environmental contaminants (mainly Hg, Se, PFASs) and the impacts of human activities on accumulation in marine ecosystems.  Hg has been released in large quantities from mining and fuel combustion and continues to cycle in the environment over long-timescales.  Some of the Hg naturally present in aquatic ecosystems is converted into methylmercury (MeHg), the only form to bioaccumulate in food webs.  A main focus of our research program is understanding how human activities have contributed to Hg enrichment in marine systems. A related question is how ecosystem characteristics such as DOC composition, organic enrichment, phytoplankton community composition affect MeHg production, bioavailability, and accumulation in marine food webs.

Ongoing Projects and People:

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  • Environmental factors driving methylation and demethylation of Hg species in oxic marine water (Amina Schartup)
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  • PFASs in seawater and plankton from the Northeast Atlantic Ocean (Xianming Zhang)
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  • Temporal trends and bioaccumulation of contaminants (PFASs, PCBs, MeHg) in pilot whale food webs from the North Atlantic (Clifton Dassuncoa, Miling Li)
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  • Methylation and demethylation of Hg species in the Arctic Ocean ice and seawater (Amina Schartup)
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  • Pharmacokinetics of  contaminant uptake and elimination in marine mammals (Jessica Ewald, Miling Li, Alicia Juang)

 

Collaborators: Dave Krabbenhoft (USGS), Bjarni Mikkelsen & Maria Dam (Faroe Islands), Lars-Eric Heimberger (CNRS), Jeroen Sonke (Toulouse), Jane Kirk (Environment Canada)

 

Support: NSF Chemical Oceanography, Nunatsiavut Government, Smith Family Foundation

 

Background:

 

We have a number of projects that are characterizing contaminant exposures using dietary surveys and probabilistic exposure simulations linked to PBPK models. We work closely with environmental epidemiologists in the School of Public Health  to understand the public health impacts of changes in environmental releases of toxicants.

 

We are particularly interested in PFASs and MeHg because of their strong association with suppressed immune function and neurocognitive development, respectively, in children. We are collaborating with researchers in the U.S., Faroe Islands, and Labrador to better understand how changes in ocean bioegochemistry and trends in chemical production are affecting children's health.

Projects and People:

 

  • Fingerprinting sources of  PFASs in different populations (Cindy Hu)
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  • Heavy metals and PFASs in drinking water from the Nurses Health Study cohort (Cindy Hu)
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  • Dietary modification of MeHg uptake from food (Paheliya Aixilafu, Miling Li)
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  • Labrador Inuit MeHg exposures from country foods (Ryan Calder)

 

Collaborators: Philippe Grandjean (Harvard), Francine Laden (Harvard), Nick Fisher (Stony Brook)

 

Support: NIH-NSF Oceans and Human Health Program, U.S. EPA, Harvard NIEHS Center, Gelfond Fund

 

- Research Sponsors -

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Sunderland Lab

Group Administrator: Brenda Mathieu

Address: 29 Oxford Street, Cambridge MA 02138

E-mail:  bmathieu [at] seas.harvard.edu

Phone: +1 (617) 496-5745

Fax: +1 (617) 495-4551