Sarah E Janssen
Sarah Janssen is an isotope geochemist working in the M3 Research Lab (MRL) located within the Upper Midwest Water Science Center.
She has a PhD in environmental chemistry from Rutgers University and a bachelor’s in chemistry from
University of the Sciences in Philadelphia. Her work focuses on the application of stable isotope techniques for understanding sources and transformations of mercury (Hg) in the environment. Her research interests include Hg cycling in contaminated ecosystems, the investigation of microbial Hg transformations using stable isotopes, and development of analytical methods to improve Hg isotope measurements.
Current Projects
- Mercury Cycling and Source Identification in the St Louis River Estuary MN/WI (collaboration with US EPA and Minnesota Pollution Control Agency)
- Mercury Isotope Fractionation during Microbial Uptake and Transformations of Hg (collaboration with Rutgers University and University of Ottawa)
- Method Development for the Pre-concentration of Waters and Low Concentration Environmental Samples for Mercury Isotopic Analysis
Education and Certifications
Ph.D. 2016, Environmental Chemistry, Rutgers University, New Brunswick, NJ
B.S. 2011, Chemistry, University of the Sciences, Philadelphia, PA
Science and Products
Filter Total Items: 38
Chemical characterization of water, sediments, and fish from Water Conservation Areas and Canals of the Florida Everglades (USA), 2012 to 2019 Chemical characterization of water, sediments, and fish from Water Conservation Areas and Canals of the Florida Everglades (USA), 2012 to 2019
This dataset includes field and laboratory measurements of surface waters, pore waters, sediment, and fish from Water Conservation Areas and adjacent canals of the Florida Everglades (USA). Water, sediment, and fish samples were collected from Water Conservation Areas 1 (Arthur R. Marshall Loxahatchee National Wildlife Refuge), 2, and 3 and neighboring canals between 2012 and 2019. The...
African fish mercury burden and isotopic composition from archived museum specimens African fish mercury burden and isotopic composition from archived museum specimens
Fish collected for taxonomic and systematic purposes are often preserved and then archived in museum collections. Preserved fish are commonly first fixed in a formalin solution and then transferred to ethanol for long-term storage. The wet preservation method can potentially introduce mercury (Hg) contamination or unintentionally extract Hg from tissue. An experiment was designed to test...
Mercury Concentrations and Loads in United States and Canadian Tributaries of Lake Superior Mercury Concentrations and Loads in United States and Canadian Tributaries of Lake Superior
In 2021, the U.S. Geological Survey (USGS) Mercury Research Laboratory (MRL) conducted a large-scale assessment of mercury (Hg) concentrations and Hg stable isotope values in tributaries of Lake Superior in order to define the sources and amounts of Hg entering the lake. Water samples were collected monthly from 18 tributaries in the United States from April through October in 2021 and...
Source Identification of Mercury and Methylmercury using Stable Isotope Analysis in the Fox River, WI Source Identification of Mercury and Methylmercury using Stable Isotope Analysis in the Fox River, WI
The lower Fox River in Wisconsin is a heavily industrialized system and the major tributary to Green Bay within Lake Michigan. The region has been a listed as Area of Concern by the United States Environmental Protection Agency (USEPA), indicating severe impairment of the ecological health of the system. Remedial action has taken place along the river to remove extensive polychlorinated...
Assessment of mercury sources in Alaskan lake food webs (version 1.1, September 2023) Assessment of mercury sources in Alaskan lake food webs (version 1.1, September 2023)
This data release includes results of raw water, soil, seston, and fish tissue samples collected from lakes in southwestern Alaska between 2011 and 2016. Specifically, these data include total mercury and methylmercury concentrations in water, size-sieved seston, and particulate matter of 13 remote lakes. Additionally, these data include soil and volcanic ash measurements from the...
Total and Methyl Mercury Water and Fish Concentrations within Everglades National Park Total and Methyl Mercury Water and Fish Concentrations within Everglades National Park
The data in this data release includes results from the analysis of water and fish from 76 sites in the Everglades National Park (ENP). Water and particulate matter samples were collected from 2008 to 2018 and analyzed for total mercury (THg) and methylmercury (MeHg). Filtered water samples were also analyzed for dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA), and...
Filter Total Items: 50
Connecting tributary mercury loads to nearshore and offshore sediments in Lake Superior Connecting tributary mercury loads to nearshore and offshore sediments in Lake Superior
Lake Superior has a vast and largely undeveloped watershed in comparison to the other Great Lakes, which makes it challenging to study mercury (Hg) sources and cycling. To examine Hg inputs to Lake Superior, we conducted an expansive binational assessment in 40 watersheds from a diverse range of landcover types. We further paired tributary Hg data to sediment source portfolios in the...
Authors
Sarah E. Janssen, Michael T. Tate, Eric D. Dantoin, Christopher T. Filstrup, Euan D Reavie, Robert M Stewart, Chris Robinson, Craig J Allan, Dale M. Robertson, David P. Krabbenhoft
Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae
Atmospheric mercury (Hg) emissions and subsequent transport and deposition are major concerns within protected lands, including national parks, where Hg can bioaccumulate to levels detrimental to human and wildlife health. Despite this risk to biological resources, there is limited understanding of the relative importance of different Hg sources and delivery pathways within protected...
Authors
Sarah E. Janssen, Christopher James Kotalik, James Willacker, Michael T. Tate, Colleen M Flanagan-Pritz, Sarah Nelson, David P. Krabbenhoft, David Walters, Collin A. Eagles-Smith
Integrated science for the study of microplastics in the environment—A strategic science vision for the U.S. Geological Survey Integrated science for the study of microplastics in the environment—A strategic science vision for the U.S. Geological Survey
Executive Summary Evidence of the widespread occurrence of microplastics throughout our environment and exposure to humans and other organisms over the past decade has led to questions about the possibility of health hazards and mitigation of exposures. This document discusses nanoplastics as well as microplastics (referred to solely as microplastics); the microplastics have a range from...
Authors
Deborah D. Iwanowicz, Austin K. Baldwin, Larry B. Barber, Vicki S. Blazer, Steven R. Corsi, Joseph W. Duris, Shawn C. Fisher, Michael Focazio, Sarah E. Janssen, Jeramy Roland Jasmann, Dana W. Kolpin, Johanna M. Kraus, Rachael F. Lane, Mari E. Lee, Kristen B. McSwain, Timothy D. Oden, Timothy J. Reilly, Andrew R. Spanjer
A conceptual site model of contaminant transport pathways from the Bremerton Naval Complex to Sinclair Inlet, Washington, 2011–21 A conceptual site model of contaminant transport pathways from the Bremerton Naval Complex to Sinclair Inlet, Washington, 2011–21
Historical activities on the Bremerton Naval Complex (BNC) in Puget Sound, Washington, have resulted in Sinclair Inlet sediments with elevated concentrations of contaminants, including organic contaminants such as polychlorinated biphenyls and trace elements including mercury. Six U.S. Geological Survey–U.S. Navy datasets have been collected since the last major assessment, in 2013, of...
Authors
Kathleen E. Conn, Sarah E. Janssen, Chad C. Opatz, Valerie A.L. Bright
Competition between dissolved organic matter and freshwater plankton control methylmercury isotope fractionation during uptake and photochemical demethylation Competition between dissolved organic matter and freshwater plankton control methylmercury isotope fractionation during uptake and photochemical demethylation
Isotope fractionation related to photochemical reactions and planktonic uptake at the base of the food web is a major uncertainty in the biological application of mercury (Hg) stable isotopes. In freshwater systems, it is unclear how competitive interactions among methylmercury (MeHg), dissolved organic matter (DOM), and phytoplankton govern the magnitude of mass-dependent and mass...
Authors
Grace Jane Armstrong, Sarah E. Janssen, Brett A. Poulin, Michael T. Tate, David P. Krabbenhoft, James P. Hurley
Mercury sources and budget for the Snake River above a hydroelectric reservoir complex Mercury sources and budget for the Snake River above a hydroelectric reservoir complex
Understanding sources of mercury (Hg) and methylmercury (MeHg) to a water body is critical for management but is often complicated by poorly characterized Hg inputs and in situ processes, such as inorganic Hg methylation. In this study, we determined inorganic Hg and MeHg concentrations and loads (filter-passing and particulate fractions) for a semi-arid 164-kilometer stretch of the...
Authors
Austin K. Baldwin, Sarah E. Janssen, Michael T. Tate, Brett Poulin, Alysa Muir Yoder, Jesse Naymik, Christopher F. Larsen, Charles Hoovestol, David P. Krabbenhoft
Non-USGS Publications**
Janssen, S.E.; Johnson, M.W.; Blum, J.D.; Barkay, T.; Reinfelder, J.R., Separation of monomethylmercury from estuarine sediments for mercury isotope analysis. Chemical Geology 2015
Janssen, S.E.; Schaefer, J.K.; Barkay, T.; Reinfelder, J.R. Fractionation of mercury stable isotopes during microbial methylmercury production in pure culture. Environ. Sci. Technol. 2016
Lloyd, N.; Janssen, S.E.; Reinfelder J.R.; Barkay, T., Exposure to mercury selects for antibiotic resistance in Fundulus heteroclitus gut microbiome, Current Microbiology, 2016
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 38
Chemical characterization of water, sediments, and fish from Water Conservation Areas and Canals of the Florida Everglades (USA), 2012 to 2019 Chemical characterization of water, sediments, and fish from Water Conservation Areas and Canals of the Florida Everglades (USA), 2012 to 2019
This dataset includes field and laboratory measurements of surface waters, pore waters, sediment, and fish from Water Conservation Areas and adjacent canals of the Florida Everglades (USA). Water, sediment, and fish samples were collected from Water Conservation Areas 1 (Arthur R. Marshall Loxahatchee National Wildlife Refuge), 2, and 3 and neighboring canals between 2012 and 2019. The...
African fish mercury burden and isotopic composition from archived museum specimens African fish mercury burden and isotopic composition from archived museum specimens
Fish collected for taxonomic and systematic purposes are often preserved and then archived in museum collections. Preserved fish are commonly first fixed in a formalin solution and then transferred to ethanol for long-term storage. The wet preservation method can potentially introduce mercury (Hg) contamination or unintentionally extract Hg from tissue. An experiment was designed to test...
Mercury Concentrations and Loads in United States and Canadian Tributaries of Lake Superior Mercury Concentrations and Loads in United States and Canadian Tributaries of Lake Superior
In 2021, the U.S. Geological Survey (USGS) Mercury Research Laboratory (MRL) conducted a large-scale assessment of mercury (Hg) concentrations and Hg stable isotope values in tributaries of Lake Superior in order to define the sources and amounts of Hg entering the lake. Water samples were collected monthly from 18 tributaries in the United States from April through October in 2021 and...
Source Identification of Mercury and Methylmercury using Stable Isotope Analysis in the Fox River, WI Source Identification of Mercury and Methylmercury using Stable Isotope Analysis in the Fox River, WI
The lower Fox River in Wisconsin is a heavily industrialized system and the major tributary to Green Bay within Lake Michigan. The region has been a listed as Area of Concern by the United States Environmental Protection Agency (USEPA), indicating severe impairment of the ecological health of the system. Remedial action has taken place along the river to remove extensive polychlorinated...
Assessment of mercury sources in Alaskan lake food webs (version 1.1, September 2023) Assessment of mercury sources in Alaskan lake food webs (version 1.1, September 2023)
This data release includes results of raw water, soil, seston, and fish tissue samples collected from lakes in southwestern Alaska between 2011 and 2016. Specifically, these data include total mercury and methylmercury concentrations in water, size-sieved seston, and particulate matter of 13 remote lakes. Additionally, these data include soil and volcanic ash measurements from the...
Total and Methyl Mercury Water and Fish Concentrations within Everglades National Park Total and Methyl Mercury Water and Fish Concentrations within Everglades National Park
The data in this data release includes results from the analysis of water and fish from 76 sites in the Everglades National Park (ENP). Water and particulate matter samples were collected from 2008 to 2018 and analyzed for total mercury (THg) and methylmercury (MeHg). Filtered water samples were also analyzed for dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA), and...
Filter Total Items: 50
Connecting tributary mercury loads to nearshore and offshore sediments in Lake Superior Connecting tributary mercury loads to nearshore and offshore sediments in Lake Superior
Lake Superior has a vast and largely undeveloped watershed in comparison to the other Great Lakes, which makes it challenging to study mercury (Hg) sources and cycling. To examine Hg inputs to Lake Superior, we conducted an expansive binational assessment in 40 watersheds from a diverse range of landcover types. We further paired tributary Hg data to sediment source portfolios in the...
Authors
Sarah E. Janssen, Michael T. Tate, Eric D. Dantoin, Christopher T. Filstrup, Euan D Reavie, Robert M Stewart, Chris Robinson, Craig J Allan, Dale M. Robertson, David P. Krabbenhoft
Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae
Atmospheric mercury (Hg) emissions and subsequent transport and deposition are major concerns within protected lands, including national parks, where Hg can bioaccumulate to levels detrimental to human and wildlife health. Despite this risk to biological resources, there is limited understanding of the relative importance of different Hg sources and delivery pathways within protected...
Authors
Sarah E. Janssen, Christopher James Kotalik, James Willacker, Michael T. Tate, Colleen M Flanagan-Pritz, Sarah Nelson, David P. Krabbenhoft, David Walters, Collin A. Eagles-Smith
Integrated science for the study of microplastics in the environment—A strategic science vision for the U.S. Geological Survey Integrated science for the study of microplastics in the environment—A strategic science vision for the U.S. Geological Survey
Executive Summary Evidence of the widespread occurrence of microplastics throughout our environment and exposure to humans and other organisms over the past decade has led to questions about the possibility of health hazards and mitigation of exposures. This document discusses nanoplastics as well as microplastics (referred to solely as microplastics); the microplastics have a range from...
Authors
Deborah D. Iwanowicz, Austin K. Baldwin, Larry B. Barber, Vicki S. Blazer, Steven R. Corsi, Joseph W. Duris, Shawn C. Fisher, Michael Focazio, Sarah E. Janssen, Jeramy Roland Jasmann, Dana W. Kolpin, Johanna M. Kraus, Rachael F. Lane, Mari E. Lee, Kristen B. McSwain, Timothy D. Oden, Timothy J. Reilly, Andrew R. Spanjer
A conceptual site model of contaminant transport pathways from the Bremerton Naval Complex to Sinclair Inlet, Washington, 2011–21 A conceptual site model of contaminant transport pathways from the Bremerton Naval Complex to Sinclair Inlet, Washington, 2011–21
Historical activities on the Bremerton Naval Complex (BNC) in Puget Sound, Washington, have resulted in Sinclair Inlet sediments with elevated concentrations of contaminants, including organic contaminants such as polychlorinated biphenyls and trace elements including mercury. Six U.S. Geological Survey–U.S. Navy datasets have been collected since the last major assessment, in 2013, of...
Authors
Kathleen E. Conn, Sarah E. Janssen, Chad C. Opatz, Valerie A.L. Bright
Competition between dissolved organic matter and freshwater plankton control methylmercury isotope fractionation during uptake and photochemical demethylation Competition between dissolved organic matter and freshwater plankton control methylmercury isotope fractionation during uptake and photochemical demethylation
Isotope fractionation related to photochemical reactions and planktonic uptake at the base of the food web is a major uncertainty in the biological application of mercury (Hg) stable isotopes. In freshwater systems, it is unclear how competitive interactions among methylmercury (MeHg), dissolved organic matter (DOM), and phytoplankton govern the magnitude of mass-dependent and mass...
Authors
Grace Jane Armstrong, Sarah E. Janssen, Brett A. Poulin, Michael T. Tate, David P. Krabbenhoft, James P. Hurley
Mercury sources and budget for the Snake River above a hydroelectric reservoir complex Mercury sources and budget for the Snake River above a hydroelectric reservoir complex
Understanding sources of mercury (Hg) and methylmercury (MeHg) to a water body is critical for management but is often complicated by poorly characterized Hg inputs and in situ processes, such as inorganic Hg methylation. In this study, we determined inorganic Hg and MeHg concentrations and loads (filter-passing and particulate fractions) for a semi-arid 164-kilometer stretch of the...
Authors
Austin K. Baldwin, Sarah E. Janssen, Michael T. Tate, Brett Poulin, Alysa Muir Yoder, Jesse Naymik, Christopher F. Larsen, Charles Hoovestol, David P. Krabbenhoft
Non-USGS Publications**
Janssen, S.E.; Johnson, M.W.; Blum, J.D.; Barkay, T.; Reinfelder, J.R., Separation of monomethylmercury from estuarine sediments for mercury isotope analysis. Chemical Geology 2015
Janssen, S.E.; Schaefer, J.K.; Barkay, T.; Reinfelder, J.R. Fractionation of mercury stable isotopes during microbial methylmercury production in pure culture. Environ. Sci. Technol. 2016
Lloyd, N.; Janssen, S.E.; Reinfelder J.R.; Barkay, T., Exposure to mercury selects for antibiotic resistance in Fundulus heteroclitus gut microbiome, Current Microbiology, 2016
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.