Jacob A Fleck
Jacob A Fleck - California Water Science Center
Science and Products
Filter Total Items: 21
No Result Found
Filter Total Items: 38
Methylmercury production in and export from agricultural wetlands in California, USA: the need to account for physical transport processes into and out of the root zone
Concentration and mass balance analyses were used to quantify methylmercury (MeHg) loads from conventional (white) rice, wild rice, and fallowed fields in northern California's Yolo Bypass. These analyses were standardized against chloride to distinguish transport pathways and net ecosystem production (NEP). During summer, chloride loads were both exported with surface water and moved into the roo
Authors
Philip A.M. Bachand, Sandra M. Bachand, Jacob A. Fleck, Charles N. Alpers, Mark Stephenson, Lisamarie Windham-Myers
Mercury cycling in agricultural and managed wetlands of California: seasonal influences of vegetation on mercury methylation, storage, and transport
Plants are a dominant biologic and physical component of many wetland capable of influencing the internal pools and fluxes of methylmercury (MeHg). To investigate their role with respect to the latter, we examined the changing seasonal roles of vegetation biomass and Hg, C and N composition from May 2007-February 2008 in 3 types of agricultural wetlands (domesticated or white rice, wild rice, and
Authors
Lisamarie Windham-Myers, Mark C. Marvin-DiPasquale, Evangelos Kakouros, Jennifer L. Agee, Le H. Kieu, Craig A. Stricker, Jacob A. Fleck, Joshua T. Ackerman
Mercury dynamics in a San Francisco estuary tidal wetland: assessing dynamics using in situ measurements
We used high-resolution in situ measurements of turbidity and fluorescent dissolved organic matter (FDOM) to quantitatively estimate the tidally driven exchange of mercury (Hg) between the waters of the San Francisco estuary and Browns Island, a tidal wetland. Turbidity and FDOM—representative of particle-associated and filter-passing Hg, respectively—together predicted 94 % of the observed variab
Authors
Brian A. Bergamaschi, Jacob A. Fleck, Bryan D. Downing, Emmanuel Boss, Brian A. Pellerin, Neil K. Ganju, David H. Schoellhamer, Amy A. Byington, Wesley A. Heim, Mark Stephenson, Roger Fujii
Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements
We assessed monomethylmercury (MeHg) dynamics in a tidal wetland over three seasons using a novel method that employs a combination of in situ optical measurements as concentration proxies. MeHg concentrations measured over a single spring tide were extended to a concentration time series using in situ optical measurements. Tidal fluxes were calculated using modeled concentrations and bi-direction
Authors
B.A. Bergamaschi, J.A. Fleck, B.D. Downing, E. Boss, B. Pellerin, N. K. Ganju, D. H. Schoellhamer, A.A. Byington, W.A. Heim, M. Stephenson, R. Fujii
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation, and environmental fate – Part 1: Field characterization
Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem health
Authors
Jacob A. Fleck, Charles N. Alpers, Mark Marvin-DiPasquale, Roger L. Hothem, Scott Wright, Kevin Ellett, Elizabeth Beaulieu, Jennifer L. Agee, Evangelos Kakouros, Le H. Kieu, Dennis D. Eberl, Alex E. Blum, Jason T. May
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation and environmental fate - Part 2: Laboratory Experiments
No abstract available.
Authors
Mark Marvin-DiPasquale, Jennifer L. Agee, Eangelos Kakouros, Le H. Kieu, Jacob A. Fleck, Charles N. Alpers
Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts
The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previ
Authors
Y.K. Henneberry, T.E.C. Kraus, J.A. Fleck, David P. Krabbenhoft, P.M. Bachand, W.R. Horwath
Methylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass
This 18-month field study addresses the seasonal and spatial patterns and processes controlling methylmercury (MeHg) production, bioaccumulation, and export from natural and agricultural wetlands of the Yolo Bypass Wildlife Area (YBWA). The data were collected in conjuntion with a Proposition 40 grant from the State Water Resources Control Board in support of the development of Best Management Pra
Authors
Lisamarie Windham-Myers, Mark Marvin-DiPasquale, Jacob Fleck, Charles N. Alpers, Joshua T. Ackerman, Collin A. Eagles-Smith, Craig Stricker, Mark Stephenson, David Feliz, Gary Gill, Philip Bachand, Ann Brice, Robin Kulakow
Mercury, methylmercury, and other constituents in sediment and water from seasonal and permanent wetlands in the Cache Creek settling basin and Yolo Bypass, Yolo County, California, 2005-06
This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three locations with
Authors
Mark Marvin-DiPasquale, Charles N. Alpers, Jacob A. Fleck
Quantifying fluxes and characterizing compositional changes of dissolved organic matter in aquatic systems in situ using combined acoustic and optical measurements
Studying the dynamics and geochemical behavior of dissolved and particulate organic material is difficult because concentration and composition may rapidly change in response to aperiodic as well as periodic physical and biological forcing. Here we describe a method useful for quantifying fluxes and analyzing dissolved organic matter (DOM) dynamics. The method uses coupled optical and acoustic mea
Authors
B.D. Downing, E. Boss, B.A. Bergamaschi, J.A. Fleck, M. A. Lionberger, N. K. Ganju, D. H. Schoellhamer, R. Fujii
A tool for assessing mercury loadings from restored tidal systems
Accurately quantifying net loads in tidal systems is difficult owing to the high variability in constituent concentrations over the vastly different time scales present in these systems. Perhaps most difficult is the measurement of fluxed over the tidal time scale. On this scale, the net export of the constituent is orders of magnitude less than the bulk exchange in either direction because of the
Authors
J.A. Fleck, B.A. Bergamaschi, B.D. Downing, M. A. Lionberger, D. H. Schoellhamer, E. Boss, M. Stephenson
Alteration of soil microbial communities and water quality in restored wetlands
Land usage is a strong determinant of soil microbial community composition and activity, which in turn determine organic matter decomposition rates and decomposition products in soils. Microbial communities in permanently flooded wetlands, such as those created by wetland restoration on Sacramento-San Joaquin Delta islands in California, function under restricted aeration conditions that result in
Authors
D.A. Bossio, J.A. Fleck, K.M. Scow, R. Fujii
Science and Products
Filter Total Items: 21
No Result Found
Filter Total Items: 38
Methylmercury production in and export from agricultural wetlands in California, USA: the need to account for physical transport processes into and out of the root zone
Concentration and mass balance analyses were used to quantify methylmercury (MeHg) loads from conventional (white) rice, wild rice, and fallowed fields in northern California's Yolo Bypass. These analyses were standardized against chloride to distinguish transport pathways and net ecosystem production (NEP). During summer, chloride loads were both exported with surface water and moved into the roo
Authors
Philip A.M. Bachand, Sandra M. Bachand, Jacob A. Fleck, Charles N. Alpers, Mark Stephenson, Lisamarie Windham-Myers
Mercury cycling in agricultural and managed wetlands of California: seasonal influences of vegetation on mercury methylation, storage, and transport
Plants are a dominant biologic and physical component of many wetland capable of influencing the internal pools and fluxes of methylmercury (MeHg). To investigate their role with respect to the latter, we examined the changing seasonal roles of vegetation biomass and Hg, C and N composition from May 2007-February 2008 in 3 types of agricultural wetlands (domesticated or white rice, wild rice, and
Authors
Lisamarie Windham-Myers, Mark C. Marvin-DiPasquale, Evangelos Kakouros, Jennifer L. Agee, Le H. Kieu, Craig A. Stricker, Jacob A. Fleck, Joshua T. Ackerman
Mercury dynamics in a San Francisco estuary tidal wetland: assessing dynamics using in situ measurements
We used high-resolution in situ measurements of turbidity and fluorescent dissolved organic matter (FDOM) to quantitatively estimate the tidally driven exchange of mercury (Hg) between the waters of the San Francisco estuary and Browns Island, a tidal wetland. Turbidity and FDOM—representative of particle-associated and filter-passing Hg, respectively—together predicted 94 % of the observed variab
Authors
Brian A. Bergamaschi, Jacob A. Fleck, Bryan D. Downing, Emmanuel Boss, Brian A. Pellerin, Neil K. Ganju, David H. Schoellhamer, Amy A. Byington, Wesley A. Heim, Mark Stephenson, Roger Fujii
Methyl mercury dynamics in a tidal wetland quantified using in situ optical measurements
We assessed monomethylmercury (MeHg) dynamics in a tidal wetland over three seasons using a novel method that employs a combination of in situ optical measurements as concentration proxies. MeHg concentrations measured over a single spring tide were extended to a concentration time series using in situ optical measurements. Tidal fluxes were calculated using modeled concentrations and bi-direction
Authors
B.A. Bergamaschi, J.A. Fleck, B.D. Downing, E. Boss, B. Pellerin, N. K. Ganju, D. H. Schoellhamer, A.A. Byington, W.A. Heim, M. Stephenson, R. Fujii
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation, and environmental fate – Part 1: Field characterization
Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem health
Authors
Jacob A. Fleck, Charles N. Alpers, Mark Marvin-DiPasquale, Roger L. Hothem, Scott Wright, Kevin Ellett, Elizabeth Beaulieu, Jennifer L. Agee, Evangelos Kakouros, Le H. Kieu, Dennis D. Eberl, Alex E. Blum, Jason T. May
The effects of sediment and mercury mobilization in the South Yuba River and Humbug Creek confluence area, Nevada County, California: Concentrations, speciation and environmental fate - Part 2: Laboratory Experiments
No abstract available.
Authors
Mark Marvin-DiPasquale, Jennifer L. Agee, Eangelos Kakouros, Le H. Kieu, Jacob A. Fleck, Charles N. Alpers
Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts
The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previ
Authors
Y.K. Henneberry, T.E.C. Kraus, J.A. Fleck, David P. Krabbenhoft, P.M. Bachand, W.R. Horwath
Methylmercury cycling, bioaccumulation, and export from agricultural and non-agricultural wetlands in the Yolo Bypass
This 18-month field study addresses the seasonal and spatial patterns and processes controlling methylmercury (MeHg) production, bioaccumulation, and export from natural and agricultural wetlands of the Yolo Bypass Wildlife Area (YBWA). The data were collected in conjuntion with a Proposition 40 grant from the State Water Resources Control Board in support of the development of Best Management Pra
Authors
Lisamarie Windham-Myers, Mark Marvin-DiPasquale, Jacob Fleck, Charles N. Alpers, Joshua T. Ackerman, Collin A. Eagles-Smith, Craig Stricker, Mark Stephenson, David Feliz, Gary Gill, Philip Bachand, Ann Brice, Robin Kulakow
Mercury, methylmercury, and other constituents in sediment and water from seasonal and permanent wetlands in the Cache Creek settling basin and Yolo Bypass, Yolo County, California, 2005-06
This report presents surface water and surface (top 0-2 cm) sediment geochemical data collected during 2005-2006, as part of a larger study of mercury (Hg) dynamics in seasonal and permanently flooded wetland habitats within the lower Sacramento River basin, Yolo County, California. The study was conducted in two phases. Phase I represented reconnaissance sampling and included three locations with
Authors
Mark Marvin-DiPasquale, Charles N. Alpers, Jacob A. Fleck
Quantifying fluxes and characterizing compositional changes of dissolved organic matter in aquatic systems in situ using combined acoustic and optical measurements
Studying the dynamics and geochemical behavior of dissolved and particulate organic material is difficult because concentration and composition may rapidly change in response to aperiodic as well as periodic physical and biological forcing. Here we describe a method useful for quantifying fluxes and analyzing dissolved organic matter (DOM) dynamics. The method uses coupled optical and acoustic mea
Authors
B.D. Downing, E. Boss, B.A. Bergamaschi, J.A. Fleck, M. A. Lionberger, N. K. Ganju, D. H. Schoellhamer, R. Fujii
A tool for assessing mercury loadings from restored tidal systems
Accurately quantifying net loads in tidal systems is difficult owing to the high variability in constituent concentrations over the vastly different time scales present in these systems. Perhaps most difficult is the measurement of fluxed over the tidal time scale. On this scale, the net export of the constituent is orders of magnitude less than the bulk exchange in either direction because of the
Authors
J.A. Fleck, B.A. Bergamaschi, B.D. Downing, M. A. Lionberger, D. H. Schoellhamer, E. Boss, M. Stephenson
Alteration of soil microbial communities and water quality in restored wetlands
Land usage is a strong determinant of soil microbial community composition and activity, which in turn determine organic matter decomposition rates and decomposition products in soils. Microbial communities in permanently flooded wetlands, such as those created by wetland restoration on Sacramento-San Joaquin Delta islands in California, function under restricted aeration conditions that result in
Authors
D.A. Bossio, J.A. Fleck, K.M. Scow, R. Fujii