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: 42
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Filter Total Items: 61
The influence of legacy contamination on the transport and bioaccumulation of mercury within the Mobile River Basin The influence of legacy contamination on the transport and bioaccumulation of mercury within the Mobile River Basin
Past industrial use and subsequent release of mercury (Hg) into the environment have resulted in severe cases of legacy contamination that still influence contemporary Hg levels in biota. While the bioaccumulation of legacy Hg is commonly assessed via concentration measurements within fish tissue, this practice becomes difficult in regions of high productivity and methylmercury (MeHg)...
Authors
Sarah E. Janssen, Michael T. Tate, David P. Krabbenhoft, John F. DeWild, Jacob M. Ogorek, Christopher L. Babiarz, Anthony Sowers, Peter L. Tuttle
Insights into mercury source identification and bioaccumulation using stable isotope approaches in the Hannibal Pool of the Ohio River Insights into mercury source identification and bioaccumulation using stable isotope approaches in the Hannibal Pool of the Ohio River
Mercury contamination in river systems due to historic and current Hg releases is a persistent concern for both wildlife and human health. In larger rivers, like the Ohio River, USA, it is difficult to directly link Hg discharges to bioaccumulation due to the existence of multiple industrial Hg sources as well as the varied dietary and migratory habits of biota. To better understand how...
Authors
Sarah E. Janssen, Kathleen A. Patnode, Bruce R Pluta, David P. Krabbenhoft
Resolving atmospheric mercury loading and source trends from isotopic records of remote North American lake sediments Resolving atmospheric mercury loading and source trends from isotopic records of remote North American lake sediments
The strongest evidence for anthropogenic alterations to the global mercury (Hg) cycle comes from historical records of mercury deposition preserved in lake sediments. Hg isotopes have added a new dimension to these sedimentary archives, promising additional insights into Hg source apportionment and biogeochemical processing. Presently, most interpretations of historical changes are...
Authors
Ryan F. Lepak, Sarah E. Janssen, Daniel R. Engstrom, David P. Krabbenhoft, Michael T. Tate, Runsheng Yin, William F. Fitzgerald, Sonia A. Nagorski, James P. Hurley
Tracing the uptake of Hg(II) in an iron-reducing bacterium using mercury stable isotopes Tracing the uptake of Hg(II) in an iron-reducing bacterium using mercury stable isotopes
Anaerobic microorganisms play a key role in the biological mercury (Hg) cycle due to their ability to produce bioaccumulative neurotoxic methylmercury (MeHg). However, despite recent advances, how bacteria accumulate inorganic Hg [Hg(II)] prior to methylation is largely unknown. In this study, we applied Hg stable isotopes to measure changes in cellular compartments of Geobacter...
Authors
Yuwei Wang, Sarah E. Janssen, Jeffra K Schaefer, Nathan Yee, John R Reinfelder
Mercury, cadmium, copper, arsenic, and selenium measurements in the feathers of adult eastern brown pelicans (Pelecanus occidentalis carolinensis) and chicks in multiple breeding grounds in the northern Gulf of Mexico Mercury, cadmium, copper, arsenic, and selenium measurements in the feathers of adult eastern brown pelicans (Pelecanus occidentalis carolinensis) and chicks in multiple breeding grounds in the northern Gulf of Mexico
The amounts of trace metals and metalloids that have been introduced into aquatic ecosystems due to anthropogenic activities have increased in recent decades. Some of these elements like mercury are easily transferred from one trophic level to another and can accumulate to toxic quantities in organisms at the top of aquatic food webs. For this reason, seabirds like the Eastern brown...
Authors
U. Ndu, J. S. Lamb, Sarah E. Janssen, R. Rossi, Y. G. Satgé, Patrick G.R. Jodice
The assessment and remediation of mercury contaminated sites: A review of current approaches The assessment and remediation of mercury contaminated sites: A review of current approaches
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial...
Authors
Chris S. Eckley, Cynthia C Gilmour, Sarah E. Janssen, Todd P Luxton, Paul M Randall, Lindsay Whalin, Carrie Austin
Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices
The development of mercury (Hg) stable isotope measurements has enhanced the study of Hg sources and transformations in the environment. As a result of the mixing of inorganic Hg (iHg) and methylmercury (MeHg) species within organisms of the aquatic food web, understanding species-specific Hg stable isotopic compositions is of significant importance. The lack of MeHg isotope measurements...
Authors
Tylor Rosera, Sarah E. Janssen, Michael T. Tate, Ryan F. Lepak, Jacob M. Ogorek, John F. DeWild, Christopher L. Babiarz, David P. Krabbenhoft, James P. Hurley
Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan
To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary...
Authors
Ryan F. Lepak, Joel C. Hoffman, Sarah E. Janssen, David P. Krabbenhoft, Jacob M. Ogorek, John F. DeWild, Michael T. Tate, Christopher L. Babiarz, Runsheng Yin, Elizabeth W Murphy, Daniel R Engstrom, James P. Hurley
Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States
Streams in the northeastern U.S. receive mercury (Hg) in varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts in fish concentrations directly back to changes in Hg source management. Mercury stable isotope tracers were utilized to relate sources of Hg to co-located fish and bed sediments from 23 streams across a forested to...
Authors
Sarah E. Janssen, Karen Riva-Murray, John F. DeWild, Jacob M. Ogorek, Michael T. Tate, Peter C. Van Metre, David P. Krabbenhoft, James F. Coles
Tracking legacy mercury in the Hackensack River Estuary using mercury stable isotopes Tracking legacy mercury in the Hackensack River Estuary using mercury stable isotopes
Spatial redistribution of legacy mercury (Hg) contamination in the Hackensack River estuary (New Jersey, USA) was evaluated using mercury stable isotopes. Total Hg varied from 0.06 to 3.8 µg g-1 in sediment from the tidal Hackensack River and from 15 to 154 µg g-1 near historically contaminated sites in upper Berry's Creek, a tributary of the Hackensack River. delta202Hg values for total...
Authors
John R Reinfelder, Sarah E. Janssen
Rapid pre-concentration of mercury in solids and water for isotopic analysis Rapid pre-concentration of mercury in solids and water for isotopic analysis
The precise quantification of mercury (Hg) stable isotope compositions in low concentration or dilute samples poses analytical challenges due to Hg mass limitations. Common Hg pre-concentration procedures require extended processing times, making rapid Hg stable isotope measurements challenging. Here we present a modified pre-concentration method that combines commonly used Hg reduction...
Authors
Sarah E. Janssen, Ryan F. Lepak, Michael T. Tate, Jacob M. Ogorek, John F. DeWild, Christopher L. Babiarz, James P. Hurley, David P. Krabbenhoft
Mercury isotopes reveal an ontogenetic shift in habitat use by walleye in lower Green Bay of Lake Michigan Mercury isotopes reveal an ontogenetic shift in habitat use by walleye in lower Green Bay of Lake Michigan
In general, fish residing in rivers differ from fish residing in lakes in their mercury (Hg) isotope ratios. Specifically, fish residing in lakes typically show enriched values for the isotope ratios of δ202Hg (mass-dependent fractionation of isotope 202Hg) and Δ199Hg (mass-independent fractionation of isotope 199Hg) compared with fish residing in rivers, because photochemical effects...
Authors
Charles P. Madenjian, Sarah E. Janssen, Ryan F. Lepak, Jacob M. Ogorek, Tylor J. Rosera, John F. DeWild, David P. Krabbenhoft, Stewart F. Cogswell, Mark E. Holey
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: 42
No Result Found
Filter Total Items: 61
The influence of legacy contamination on the transport and bioaccumulation of mercury within the Mobile River Basin The influence of legacy contamination on the transport and bioaccumulation of mercury within the Mobile River Basin
Past industrial use and subsequent release of mercury (Hg) into the environment have resulted in severe cases of legacy contamination that still influence contemporary Hg levels in biota. While the bioaccumulation of legacy Hg is commonly assessed via concentration measurements within fish tissue, this practice becomes difficult in regions of high productivity and methylmercury (MeHg)...
Authors
Sarah E. Janssen, Michael T. Tate, David P. Krabbenhoft, John F. DeWild, Jacob M. Ogorek, Christopher L. Babiarz, Anthony Sowers, Peter L. Tuttle
Insights into mercury source identification and bioaccumulation using stable isotope approaches in the Hannibal Pool of the Ohio River Insights into mercury source identification and bioaccumulation using stable isotope approaches in the Hannibal Pool of the Ohio River
Mercury contamination in river systems due to historic and current Hg releases is a persistent concern for both wildlife and human health. In larger rivers, like the Ohio River, USA, it is difficult to directly link Hg discharges to bioaccumulation due to the existence of multiple industrial Hg sources as well as the varied dietary and migratory habits of biota. To better understand how...
Authors
Sarah E. Janssen, Kathleen A. Patnode, Bruce R Pluta, David P. Krabbenhoft
Resolving atmospheric mercury loading and source trends from isotopic records of remote North American lake sediments Resolving atmospheric mercury loading and source trends from isotopic records of remote North American lake sediments
The strongest evidence for anthropogenic alterations to the global mercury (Hg) cycle comes from historical records of mercury deposition preserved in lake sediments. Hg isotopes have added a new dimension to these sedimentary archives, promising additional insights into Hg source apportionment and biogeochemical processing. Presently, most interpretations of historical changes are...
Authors
Ryan F. Lepak, Sarah E. Janssen, Daniel R. Engstrom, David P. Krabbenhoft, Michael T. Tate, Runsheng Yin, William F. Fitzgerald, Sonia A. Nagorski, James P. Hurley
Tracing the uptake of Hg(II) in an iron-reducing bacterium using mercury stable isotopes Tracing the uptake of Hg(II) in an iron-reducing bacterium using mercury stable isotopes
Anaerobic microorganisms play a key role in the biological mercury (Hg) cycle due to their ability to produce bioaccumulative neurotoxic methylmercury (MeHg). However, despite recent advances, how bacteria accumulate inorganic Hg [Hg(II)] prior to methylation is largely unknown. In this study, we applied Hg stable isotopes to measure changes in cellular compartments of Geobacter...
Authors
Yuwei Wang, Sarah E. Janssen, Jeffra K Schaefer, Nathan Yee, John R Reinfelder
Mercury, cadmium, copper, arsenic, and selenium measurements in the feathers of adult eastern brown pelicans (Pelecanus occidentalis carolinensis) and chicks in multiple breeding grounds in the northern Gulf of Mexico Mercury, cadmium, copper, arsenic, and selenium measurements in the feathers of adult eastern brown pelicans (Pelecanus occidentalis carolinensis) and chicks in multiple breeding grounds in the northern Gulf of Mexico
The amounts of trace metals and metalloids that have been introduced into aquatic ecosystems due to anthropogenic activities have increased in recent decades. Some of these elements like mercury are easily transferred from one trophic level to another and can accumulate to toxic quantities in organisms at the top of aquatic food webs. For this reason, seabirds like the Eastern brown...
Authors
U. Ndu, J. S. Lamb, Sarah E. Janssen, R. Rossi, Y. G. Satgé, Patrick G.R. Jodice
The assessment and remediation of mercury contaminated sites: A review of current approaches The assessment and remediation of mercury contaminated sites: A review of current approaches
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial...
Authors
Chris S. Eckley, Cynthia C Gilmour, Sarah E. Janssen, Todd P Luxton, Paul M Randall, Lindsay Whalin, Carrie Austin
Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices Isolation of methylmercury using distillation and anion-exchange chromatography for isotopic analyses in natural matrices
The development of mercury (Hg) stable isotope measurements has enhanced the study of Hg sources and transformations in the environment. As a result of the mixing of inorganic Hg (iHg) and methylmercury (MeHg) species within organisms of the aquatic food web, understanding species-specific Hg stable isotopic compositions is of significant importance. The lack of MeHg isotope measurements...
Authors
Tylor Rosera, Sarah E. Janssen, Michael T. Tate, Ryan F. Lepak, Jacob M. Ogorek, John F. DeWild, Christopher L. Babiarz, David P. Krabbenhoft, James P. Hurley
Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan
To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary...
Authors
Ryan F. Lepak, Joel C. Hoffman, Sarah E. Janssen, David P. Krabbenhoft, Jacob M. Ogorek, John F. DeWild, Michael T. Tate, Christopher L. Babiarz, Runsheng Yin, Elizabeth W Murphy, Daniel R Engstrom, James P. Hurley
Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States Chemical and physical controls on mercury source signatures in stream fish from the northeastern United States
Streams in the northeastern U.S. receive mercury (Hg) in varying proportions from atmospheric deposition and legacy point sources, making it difficult to attribute shifts in fish concentrations directly back to changes in Hg source management. Mercury stable isotope tracers were utilized to relate sources of Hg to co-located fish and bed sediments from 23 streams across a forested to...
Authors
Sarah E. Janssen, Karen Riva-Murray, John F. DeWild, Jacob M. Ogorek, Michael T. Tate, Peter C. Van Metre, David P. Krabbenhoft, James F. Coles
Tracking legacy mercury in the Hackensack River Estuary using mercury stable isotopes Tracking legacy mercury in the Hackensack River Estuary using mercury stable isotopes
Spatial redistribution of legacy mercury (Hg) contamination in the Hackensack River estuary (New Jersey, USA) was evaluated using mercury stable isotopes. Total Hg varied from 0.06 to 3.8 µg g-1 in sediment from the tidal Hackensack River and from 15 to 154 µg g-1 near historically contaminated sites in upper Berry's Creek, a tributary of the Hackensack River. delta202Hg values for total...
Authors
John R Reinfelder, Sarah E. Janssen
Rapid pre-concentration of mercury in solids and water for isotopic analysis Rapid pre-concentration of mercury in solids and water for isotopic analysis
The precise quantification of mercury (Hg) stable isotope compositions in low concentration or dilute samples poses analytical challenges due to Hg mass limitations. Common Hg pre-concentration procedures require extended processing times, making rapid Hg stable isotope measurements challenging. Here we present a modified pre-concentration method that combines commonly used Hg reduction...
Authors
Sarah E. Janssen, Ryan F. Lepak, Michael T. Tate, Jacob M. Ogorek, John F. DeWild, Christopher L. Babiarz, James P. Hurley, David P. Krabbenhoft
Mercury isotopes reveal an ontogenetic shift in habitat use by walleye in lower Green Bay of Lake Michigan Mercury isotopes reveal an ontogenetic shift in habitat use by walleye in lower Green Bay of Lake Michigan
In general, fish residing in rivers differ from fish residing in lakes in their mercury (Hg) isotope ratios. Specifically, fish residing in lakes typically show enriched values for the isotope ratios of δ202Hg (mass-dependent fractionation of isotope 202Hg) and Δ199Hg (mass-independent fractionation of isotope 199Hg) compared with fish residing in rivers, because photochemical effects...
Authors
Charles P. Madenjian, Sarah E. Janssen, Ryan F. Lepak, Jacob M. Ogorek, Tylor J. Rosera, John F. DeWild, David P. Krabbenhoft, Stewart F. Cogswell, Mark E. Holey
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.