Denis R LeBlanc (Former Employee)
Science and Products
Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts
Temperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015.
Poly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
Evaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier
Geochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts
Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was
Microbial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview
Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake
Importance of the colmation layer in the transport and removal of cyanobacteria, viruses, and dissolved organic carbon during natural lake-bank filtration
Science for the stewardship of the groundwater resources of Cape Cod, Massachusetts
Mercury speciation and mobilization in a wastewater-contaminated groundwater plume
Transport of nitrogen in a treated-wastewater plume to coastal discharge areas, Ashumet Valley, Cape Cod, Massachusetts
Long-term groundwater contamination after source removal—The role of sorbed carbon and nitrogen on the rate of reoxygenation of a treated-wastewater plume on Cape Cod, MA, USA
Comparison of no-purge and pumped sampling methods for monitoring concentrations of ordnance-related compounds in groundwater, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts, 2009-2010
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Geochemical data supporting analysis of geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts
This data release provides analytical and other data in support of an analysis of nitrogen transport and transformation in groundwater and in a subterranean estuary in the Eel River and onshore locations on the Seacoast Shores peninsula, Falmouth, Massachusetts. The analysis is described in U.S. Geological Survey Scientific Investigations Report 2018-5095 by Colman and others (2018). This data relTemperature and seepage data from a lake-bottom permeable reactive barrier, Ashumet Pond, Falmouth, MA, 2004-2015.
These data were collected to evaluate groundwater/surface-water exchange in the area of a lake-bottom permeable reactive barrier and to assess changes in groundwater seepage over the period between 2004 and 2015. This data release includes geospatial datasets, comma separated values (.csv) files, and associated FGDC-compliant metadata representing data collected between 2004 and 2015 as part of aPoly- and perfluoalkyl substances in contaminated groundwater, Cape Cod, Massachusetts, 2014-2016
Drinking water health advisories for perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), were issued by the U.S. Environmental Protection Agency in 2016 in response to growing evidence associated with negative human health effects. PFOA and PFOS are often associated with other poly- and perfluorinated alkyl substances (PFAS). There has been increasing concern for groundwater quality o - Maps
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Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Groundwater discharge delivering anthropogenic N from surrounding watersheds can impact lake nutrient budgets. However, upgradient groundwater processes and changing dynamics in N biogeochemistry at the groundwater-lake interface are complex and difficult to resolve. In this study, hydrograph variations in a groundwater flow-through lake altered discharge patterns of a wastewater-derived, grounAuthorsRichard L. Smith, Deborah A. Repert, Deborah Stoliker, Douglas B. Kent, Bongkeun Song, Denis R. LeBlanc, Timothy McCobb, John K. Böhlke, Sung Pil Hyun, Hee Sun MoonGeochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
Nitrogen transport and transformation were studied during 2013 to 2014 by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, in a subterranean estuary beneath onshore locations on the Seacoast Shores peninsula, a residential area in Falmouth, Massachusetts, served by septic systems and cesspools, and adjacent offshore locations in the Eel River, a saltwater eAuthorsJohn A. Colman, Denis R. LeBlanc, John K. Böhlke, Timothy D. McCobb, Kevin D. Kroeger, Marcel Belaval, Thomas C. Cambareri, Gillian F. Pirolli, T. Wallace Brooks, Mary E. Garren, Tobias B. Stover, Ann KeeleyEvaluating long-term patterns of decreasing groundwater discharge through a lake-bottom permeable reactive barrier
Identifying and quantifying groundwater exchange is critical when considering contaminant fate and transport at the groundwater/surface-water interface. In this paper, areally distributed temperature and point seepage measurements are used to efficiently assess spatial and temporal groundwater discharge patterns through a glacial-kettle lakebed area containing a zero-valent iron permeable reactiveAuthorsTimothy D. McCobb, Martin A. Briggs, Denis R. LeBlanc, Frederick D. Day-Lewis, Carole D. JohnsonGeochemical and hydrologic factors controlling subsurface transport of poly- and perfluoroalkyl substances, Cape Cod, Massachusetts
Growing evidence that certain poly- and perfluoroalkyl substances (PFASs) are associated with negative human health effects prompted the U.S. Environmental Protection Agency to issue lifetime drinking water health advisories for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in 2016. Given that groundwater is a major source of drinking water, the main objective of this work was
AuthorsAndrea K. Weber, Larry B. Barber, Denis R. LeBlanc, Elsie M. Sunderland, Chad D. VecitisMicrobial-sized, carboxylate-modified microspheres as surrogate tracers in a variety of subsurface environments: An overview
Since 1986, fluorescent carboxylate-modified polystyrene/latex microspheres (FCM) have been co-injected into aquifers along with conservative tracers and viruses, bacteria, and (or) protozoa. Use of FCM has resulted in new information about subsurface transport behaviors of microorganisms in fractured crystalline rock, karst limestone, soils, and granular aquifers. FCM have been used as surrogatesAuthorsRonald W. Harvey, David W. Metge, Denis R. LeBlancHydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake
The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepageAuthorsDeborah L. Stoliker, Deborah A. Repert, Richard L. Smith, Bongkeun Song, Denis R. LeBlanc, Timothy D. McCobb, Christopher Conaway, Sung Pil Hyun, Dong-Chan Koh, Hee Sun Moon, Douglas B. KentImportance of the colmation layer in the transport and removal of cyanobacteria, viruses, and dissolved organic carbon during natural lake-bank filtration
This study focused on the importance of the colmation layer in the removal of cyanobacteria, viruses, and dissolved organic carbon (DOC) during natural bank filtration. Injection-and-recovery studies were performed at two shallow (0.5 m deep), sandy, near-shore sites at the southern end of Ashumet Pond, a waste-impacted, kettle pond on Cape Cod, MA, that is subject to periodic blooms of cyanobacteAuthorsRonald W. Harvey, David W. Metge, Denis R. LeBlanc, Jennifer C. Underwood, George R. Aiken, Kenna D. Butler, Timothy D. McCobb, Jay JasperseScience for the stewardship of the groundwater resources of Cape Cod, Massachusetts
Groundwater is the sole source of drinking water and a major source of freshwater for domestic, industrial, and agricultural uses on Cape Cod, Massachusetts. Groundwater discharged from aquifers also supports freshwater pond and stream ecosystems and coastal wetlands. Six hydraulically distinct groundwater-flow systems (lenses) have been delineated on Cape Cod. Of the approximately 450 million galAuthorsJeffrey R. Barbaro, John P. Masterson, Denis R. LeBlancMercury speciation and mobilization in a wastewater-contaminated groundwater plume
We measured the concentration and speciation of mercury (Hg) in groundwater down-gradient from the site of wastewater infiltration beds operated by the Massachusetts Military Reservation, western Cape Cod, Massachusetts. Total mercury concentrations in oxic, mildly acidic, uncontaminated groundwater are 0.5–1 pM, and aquifer sediments have 0.5–1 ppb mercury. The plume of impacted groundwater creatAuthorsCarl H. Lamborg, Doug B. Kent, Gretchen J. Swarr, Kathleen M. Munson, Tristan Kading, Alison E. O'Connor, Gillian M. Fairchild, Denis R. LeBlanc, Heather A. WiatrowskiTransport of nitrogen in a treated-wastewater plume to coastal discharge areas, Ashumet Valley, Cape Cod, Massachusetts
Land disposal of treated wastewater from a treatment plant on the Massachusetts Military Reservation in operation from 1936 to 1995 has created a plume of contaminated groundwater that is migrating toward coastal discharge areas in the town of Falmouth, Massachusetts. To develop a better understanding of the potential impact of the treated-wastewater plume on coastal discharge areas, the U.S. GeolAuthorsJeffrey R. Barbaro, Donald A. Walter, Denis R. LeBlancLong-term groundwater contamination after source removal—The role of sorbed carbon and nitrogen on the rate of reoxygenation of a treated-wastewater plume on Cape Cod, MA, USA
The consequences of groundwater contamination can remain long after a contaminant source has been removed. Documentation of natural aquifer recoveries and empirical tools to predict recovery time frames and associated geochemical changes are generally lacking. This study characterized the long-term natural attenuation of a groundwater contaminant plume in a sand and gravel aquifer on Cape Cod, MasAuthorsRichard L. Smith, Deborah A. Repert, Larry B. Barber, Denis R. LeBlancComparison of no-purge and pumped sampling methods for monitoring concentrations of ordnance-related compounds in groundwater, Camp Edwards, Massachusetts Military Reservation, Cape Cod, Massachusetts, 2009-2010
Field tests were conducted near the Impact Area at Camp Edwards on the Massachusetts Military Reservation, Cape Cod, Massachusetts, to determine the utility of no-purge groundwater sampling for monitoring concentrations of ordnance-related explosive compounds and perchlorate in the sand and gravel aquifer. The no-purge methods included (1) a diffusion sampler constructed of rigid porous polyethyleAuthorsJennifer G. Savoie, Denis R. LeBlanc - News