Kevin D Kroeger, PhD
Kevin Kroeger has studied coastal ecosystems since 1990, with focus on a range of topics including fluxes and biogeochemistry of nitrogen in groundwater discharge to estuaries and wetlands, estuarine water quality, and carbon and greenhouse gas cycling and fluxes in coastal wetlands.
Kroeger is lead of the Biogeochemical Processes group at Woods Hole Coastal and Marine Science Center, and lead of a new project titled: Biogeochemical Drivers of Wetland Persistence and Feedbacks on Coastal Hazards The objectives of this Project are to provide guidance to federal (National Park Service, Fish & Wildlife Service, Army Corp of Engineers), state, local and private land owners and managers regarding stability and persistence of coastal wetlands under a range of hydrological management conditions and changing environmental conditions. Tidal wetlands provide critical services to society, including protection of infrastructure from coastal hazards, and habitat provision for economically important species. A large fraction of U.S. tidal wetlands, however, has been lost or degraded during recent centuries due to human actions, largely related to development and utilization of coastal lands. Feedbacks and interactions among natural and anthropogenic drivers have altered the stability and persistence of coastal wetlands. Decisions regarding hydrological management can alter the balance of organic matter production, retention and preservation, and thus management actions can either promote wetland persistence and resilience, or cause catastrophic loss of elevation, putting coastal infrastructure at increased risk of flooding or storm damage. This project impacts wetland management decisions. The contiguous U.S. has close to 2 million hectares of estuarine and marine wetlands. Nearly all of that area is under some level of management, with the federal government being the largest single manager. Land managers at FWS and NPS, and flood managers at ACOE, must make decisions regarding whether to spend substantial funds to maintain, repair and enhance water control structures under increasing rates of sea level change, or alternatively whether to reduce or remove hydrological management, to restore managed wetlands to more natural hydrology and enhance the capability of wetlands to build elevation over time, and to migrate landward. Society needs guidance and predictions regarding the result of those decisions for continued elevation gain, migration, and ongoing persistence of the wetlands.
Professional Experience
Present: Research Chemist, USGS Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA
2004-2006: Mendenhall Fellow, US Geological Survey Geologic Division, St Petersburg, FL
2003-2004: Postdoctoral Scholar, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA
1997-2003: Research Fellow and Teaching Fellow, Bos
Education and Certifications
PhD Boston University Marine Program (Biogeochemistry)
M.S. University of Connecticut (Marine Science)
B.A. University of Tennessee (Ecology)
Affiliations and Memberships*
Contributing Author: 2nd State of the Carbon Cycle Report (SOCCR-2), Chapter 15 Tidal Wetlands and Estuaries
Lead, USGS Woods Hole Coastal Biogeochemical Processes Project
Participant, 2017 EPA AFOL
Science and Products
Limited denitrification in glacial deposit aquifers having thick unsaturated zones (Long Island, USA)
Continuous resistivity profiling data from Great South Bay, Long Island, New York
Continuous resistivity profiling data from Northport Harbor and Manhasset Bay, Long Island, New York
Continuous resistivity profiling data from the Corsica River Estuary, Maryland
Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N2O
Use of pharmaceuticals and pesticides to constrain nutrient sources in coastal groundwater of northwestern Long Island, New York, USA
Nitrogen biogeochemistry of submarine groundwater discharge
Identifying nutrient sources to three lagoons at Ofu and Olosega, American Samoa using δ15N of benthic macroalgae
Submarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer
Ra and Rn isotopes as natural tracers of submarine groundwater discharge in Tampa Bay, Florida
Submarine ground-water discharge: nutrient loading and nitrogen transformations
Effects of watershed land use on nitrogen concentrations and δ15 nitrogen in groundwater
Science and Products
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Limited denitrification in glacial deposit aquifers having thick unsaturated zones (Long Island, USA)
The goal of this study was to demonstrate how the extent of denitrification, which is indirectly related to dissolved organ carbon and directly related to oxygen concentrations, can also be linked to unsaturated-zone thickness, a mappable aquifer property. Groundwater from public supply and monitoring wells in Northport on Long Island, New York state (USA), were analyzed for denitrification reactiAuthorsCaitlin Young, Kevin D. Kroeger, Gilbert HansonContinuous resistivity profiling data from Great South Bay, Long Island, New York
An investigation of submarine aquifers adjacent to the Fire Island National Seashore and Long Island, New York was conducted to assess the importance of submarine groundwater discharge as a potential nonpoint source of nitrogen delivery to Great South Bay. Over 200 kilometers of continuous resistivity profiling data were collected to image the fresh-saline groundwater interface in sediments beneatAuthorsV.A. Cross, J.F. Bratton, K.D. Kroeger, John Crusius, C.R. WorleyContinuous resistivity profiling data from Northport Harbor and Manhasset Bay, Long Island, New York
An investigation of coastal groundwater systems was performed along the North Shore of Long Island, New York, during May 2008 to constrain nutrient delivery to Northport Harbor and Manhasset Bay by delineating locations of likely groundwater discharge. The embayments are bounded by steep moraines and are underlain by thick, fine-grained sediments deposited in proglacial lakes during the last ice aAuthorsV.A. Cross, J.F. Bratton, John Crusius, K.D. Kroeger, C.R. WorleyContinuous resistivity profiling data from the Corsica River Estuary, Maryland
Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuarAuthorsV.A. Cross, J.F. Bratton, C.R. Worley, John Crusius, K.D. KroegerShort-term nitrogen additions can shift a coastal wetland from a sink to a source of N2O
Coastal salt marshes sequester carbon at high rates relative to other ecosystems and emit relatively little methane particularly compared to freshwater wetlands. However, fluxes of all major greenhouse gases (N2O, CH4, and CO2) need to be quantified for accurate assessment of the climatic roles of these ecosystems. Anthropogenic nitrogen inputs (via run-off, atmospheric deposition, and wastewater)AuthorsSerena Moseman-Valtierra, Rosalinda Gonzalez, Kevin D. Kroeger, Jianwu Tang, Wei Chun Chao, John Crusius, John F. Bratton, Adrian G. Mann, James SheltonUse of pharmaceuticals and pesticides to constrain nutrient sources in coastal groundwater of northwestern Long Island, New York, USA
In developed, non-agricultural, unsewered areas, septic systems and fertilizer application to lawns and gardens represent two major sources of nitrogen to coastal groundwater, in addition to atmospheric input. This study was designed to distinguish between these two possible nitrogen sources by analyzing groundwater samples for pharmaceutical residuals, because fertilizers do not contain any of thAuthorsS. Zhao, P. Zhang, John Crusius, K.D. Kroeger, J.F. BrattonNitrogen biogeochemistry of submarine groundwater discharge
To investigate the role of the seepage zone in transport, chemical speciation, and attenuation of nitrogen loads carried by submarine groundwater discharge, we collected nearshore groundwater samples (n = 328) and examined the distribution and isotopic signature (δ15N) of nitrate and ammonium. In addition, we estimated nutrient fluxes from terrestrial and marine groundwater sources. We discuss ourAuthorsK.D. Kroeger, M.A. CharetteIdentifying nutrient sources to three lagoons at Ofu and Olosega, American Samoa using δ15N of benthic macroalgae
Degradation of nearshore habitats is a serious problem in some areas of American Samoa, such as in Pago Pago Harbor on Tutuila Island, and is a smaller but chronic problem in other areas. Sedimentation, pollution, nutrient enrichment from surface runoff or groundwater, and trampling are the major factors causing the changes (Peshut and Brooks, 2005). On the outer islands of Ofu and Olosega (Manu’aAuthorsVirginia H. Garrison, Kevin D. Kroeger, Douglas Fenner, Peter CraigSubmarine groundwater discharge to Tampa Bay: Nutrient fluxes and biogeochemistry of the coastal aquifer
To separately quantify the roles of fresh and saline submarine groundwater discharge (SGD), relative to that of rivers, in transporting nutrients to Tampa Bay, Florida, we used three approaches (Darcy's Law calculations, a watershed water budget, and a 222Rn mass-balance) to estimate rate of SGD from the Pinellas peninsula. Groundwater samples were collected in 69 locations in the coastal aquiferAuthorsKevin D. Kroeger, Peter W. Swarzenski, Wm. Jason Greenwood, Christopher ReichRa and Rn isotopes as natural tracers of submarine groundwater discharge in Tampa Bay, Florida
A suite of naturally occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra) were studied during wet and dry conditions in Tampa Bay, Florida, to evaluate their utility as groundwater discharge tracers, both within the bay proper and within the Alafia River/estuary — a prominent free-flowing river that empties into the bay. In Tampa Bay, almost 30% of the combined riverine inpuAuthorsP.W. Swarzenski, C. Reich, K.D. Kroeger, M. BaskaranSubmarine ground-water discharge: nutrient loading and nitrogen transformations
Eutrophication of coastal waters due to nonpoint source land-derived nitrogen (N) loads is a worldwide phenomenon and perhaps the greatest agent of change altering coastal ecology (National Research Council, 2000; Howarth and others, 2000). Within the United States, a majority of estuaries have been determined to be moderately to severely impaired by eutrophication associated with increasing nutriAuthorsKevin D. Kroeger, Peter W. Swarzenski, John Crusius, John F. Bratton, Matthew A. CharetteEffects of watershed land use on nitrogen concentrations and δ15 nitrogen in groundwater
Eutrophication is a major agent of change affecting freshwater, estuarine, and marine systems. It is largely driven by transportation of nitrogen from natural and anthropogenic sources. Research is needed to quantify this nitrogen delivery and to link the delivery to specific land-derived sources. In this study we measured nitrogen concentrations and δ 15N values in seepage water entering three frAuthorsMarci L. Cole, Kevin D. Kroeger, J.W. McClelland, I. Valiela - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government