Bryan Downing (Former Employee)
Science and Products
Filter Total Items: 14
Continuous underway water quality and water isotope measurements in a hydrodynamically complex tidal environment
Real-time, high frequency (1-second sample interval) GPS location, water quality, and water isotope (δ2H, δ18O) data was collected in the Cache Slough Complex (CSC), located in the northern San Francisco Bay Delta (SFBD). Data was collected on 10/01/2014 for an approximate 4-hour period (10:30 14:30 h PST) while underway on the R/V Mary Landsteiner, a 26-foot USGS vessel. Sample water was pumped
Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model
Regional models of tidal marsh elevation response to sea-level rise are needed to support coastal climate change adaptation decisions, including those related to land use planning, habitat management and infrastructure design. The Marsh Equilibrium Model (MEM) is a one-dimensional mechanistic elevation model that incorporates feedbacks of organic and inorganic inputs within the tidal frame to proj
Filter Total Items: 38
Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California
Executive SummaryThis report is the second in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). The purpose of this report is to synthesize the data available from a nutrient and water-quality HF (about every 15 minutes) monitoring network operated by the U.S. Geolo
Authors
Bryan D. Downing, Brian A. Bergamaschi, Tamara E.C. Kraus
An introduction to high-frequency nutrient and biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California
Executive SummaryThis report is the first in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). This first report provides an introduction to the reasons for and fundamental concepts behind collecting HF measurements, and describes the benefits associated with a real
Authors
Tamara E.C. Kraus, Brian A. Bergamaschi, Bryan D. Downing
Clearing the waters: Evaluating the need for site-specific field fluorescence corrections based on turbidity measurements
In situ fluorescent dissolved organic matter (fDOM) measurements have gained increasing popularity as a proxy for dissolved organic carbon (DOC) concentrations in streams. One challenge to accurate fDOM measurements in many streams is light attenuation due to suspended particles. Downing et al. (2012) evaluated the need for corrections to compensate for particle interference on fDOM measurements u
Authors
John Franco Saraceno, James B. Shanley, Bryan D. Downing, Brian A. Pellerin
A river-scale Lagrangian experiment examining controls on phytoplankton dynamics in the presence and absence of treated wastewater effluent high in ammonium
Phytoplankton are critical component of the food web in most large rivers and estuaries, and thus identifying dominant controls on phytoplankton abundance and species composition is important to scientists, managers, and policymakers. Recent studies from a variety of systems indicate that ammonium ( NH+4) in treated wastewater effluent decreases primary production and alters phytoplankton species
Authors
Tamara E. C. Kraus, Kurt D. Carpenter, Brian A. Bergamaschi, Alexander Parker, Elizabeth B. Stumpner, Bryan D. Downing, Nicole Travis, Frances Wilkerson, Carol Kendall, Timothy Mussen
Using continuous underway isotope measurements to map water residence time in hydrodynamically complex tidal environments
Stable isotopes present in water (δ2H, δ18O) have been used extensively to evaluate hydrological processes on the basis of parameters such as evaporation, precipitation, mixing, and residence time. In estuarine aquatic habitats, residence time (τ) is a major driver of biogeochemical processes, affecting trophic subsidies and conditions in fish-spawning habitats. But τ is highly variable in estuari
Authors
Bryan D. Downing, Brian A. Bergamaschi, Carol Kendall, Tamara E. C. Kraus, Kate J. Dennis, Jeffery A. Carter, Travis von Dessonneck
Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model
Reducing uncertainty in data inputs at relevant spatial scales can improve tidal marsh forecasting models, and their usefulness in coastal climate change adaptation decisions. The Marsh Equilibrium Model (MEM), a one-dimensional mechanistic elevation model, incorporates feedbacks of organic and inorganic inputs to project elevations under sea-level rise scenarios. We tested the feasibility of deri
Authors
Kristin B. Byrd, Lisamarie Windham-Myers, Thomas Leeuw, Bryan D. Downing, James T. Morris, Matthew C. Ferner
Optical properties of dissolved organic matter (DOM): Effects of biological and photolytic degradation
Advances in spectroscopic techniques have led to an increase in the use of optical properties (absorbance and fluorescence) to assess dissolved organic matter (DOM) composition and infer sources and processing. However, little information is available to assess the impact of biological and photolytic processing on the optical properties of original DOM source materials. We measured changes in comm
Authors
Angela Hansen, Tamara E. C. Kraus, Brian Pellerin, Jacob Fleck, Bryan D. Downing, Brian A. Bergamaschi
High-resolution remote sensing of water quality in the San Francisco Bay-Delta Estuary
The San Francisco Bay–Delta Estuary watershed is a major source of freshwater for California and a profoundly human-impacted environment. The water quality monitoring that is critical to the management of this important water resource and ecosystem relies primarily on a system of fixed water-quality monitoring stations, but the limited spatial coverage often hinders understanding. Here, we show ho
Authors
Cédric G. Fichot, Bryan D. Downing, Brian A. Bergamaschi, Lisamarie Windham-Myers, Mark C. Marvin-DiPasquale, David R. Thompson, Michelle M. Gierach
Mississippi River nitrate loads from high frequency sensor measurements and regression-based load estimation
Accurately quantifying nitrate (NO3–) loading from the Mississippi River is important for predicting summer hypoxia in the Gulf of Mexico and targeting nutrient reduction within the basin. Loads have historically been modeled with regression-based techniques, but recent advances with high frequency NO3– sensors allowed us to evaluate model performance relative to measured loads in the lower Missis
Authors
Brian A. Pellerin, Brian A. Bergamaschi, Robert J. Gilliom, Charles G. Crawford, John Franco Saraceno, C. Paul Frederick, Bryan D. Downing, Jennifer C. Murphy
Experimental design and quality assurance: in situ fluorescence instrumentation
Both instrument design and capabilities of fluorescence spectroscopy have greatly advanced over the last several decades. Advancements include solid-state excitation sources, integration of fiber optic technology, highly sensitive multichannel detectors, rapid-scan monochromators, sensitive spectral correction techniques, and improve data manipulation software (Christian et al., 1981, Lochmuller a
Authors
Robyn N. Conmy, Carlos E. Del Castillo, Bryan D. Downing, Robert F. Chen
Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter
Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury
Authors
Jacob A. Fleck, Gary W. Gill, Brian A. Bergamaschi, Tamara E.C. Kraus, Bryan D. Downing, Charles N. Alpers
Groundwater contributions of flow, nitrate, and dissolved organic carbon to the lower San Joaquin River, California, 2006-08
The influence of groundwater on surface-water quality in the San Joaquin River, California, was examined for a 59-mile reach from the confluence with Salt Slough to Vernalis. The primary objective of this study was to quantify the rate of groundwater discharged to the lower San Joaquin River and the contribution of nitrate and dissolved organic carbon concentrations to the river. Multiple lines of
Authors
Celia Zamora, Randy A. Dahlgren, Charles R. Kratzer, Bryan D. Downing, Ann D. Russell, Peter D. Dileanis, Brian A. Bergamaschi, Steven P. Phillips
Science and Products
Filter Total Items: 14
Continuous underway water quality and water isotope measurements in a hydrodynamically complex tidal environment
Real-time, high frequency (1-second sample interval) GPS location, water quality, and water isotope (δ2H, δ18O) data was collected in the Cache Slough Complex (CSC), located in the northern San Francisco Bay Delta (SFBD). Data was collected on 10/01/2014 for an approximate 4-hour period (10:30 14:30 h PST) while underway on the R/V Mary Landsteiner, a 26-foot USGS vessel. Sample water was pumped
Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model
Regional models of tidal marsh elevation response to sea-level rise are needed to support coastal climate change adaptation decisions, including those related to land use planning, habitat management and infrastructure design. The Marsh Equilibrium Model (MEM) is a one-dimensional mechanistic elevation model that incorporates feedbacks of organic and inorganic inputs within the tidal frame to proj
Filter Total Items: 38
Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California
Executive SummaryThis report is the second in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). The purpose of this report is to synthesize the data available from a nutrient and water-quality HF (about every 15 minutes) monitoring network operated by the U.S. Geolo
Authors
Bryan D. Downing, Brian A. Bergamaschi, Tamara E.C. Kraus
An introduction to high-frequency nutrient and biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California
Executive SummaryThis report is the first in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). This first report provides an introduction to the reasons for and fundamental concepts behind collecting HF measurements, and describes the benefits associated with a real
Authors
Tamara E.C. Kraus, Brian A. Bergamaschi, Bryan D. Downing
Clearing the waters: Evaluating the need for site-specific field fluorescence corrections based on turbidity measurements
In situ fluorescent dissolved organic matter (fDOM) measurements have gained increasing popularity as a proxy for dissolved organic carbon (DOC) concentrations in streams. One challenge to accurate fDOM measurements in many streams is light attenuation due to suspended particles. Downing et al. (2012) evaluated the need for corrections to compensate for particle interference on fDOM measurements u
Authors
John Franco Saraceno, James B. Shanley, Bryan D. Downing, Brian A. Pellerin
A river-scale Lagrangian experiment examining controls on phytoplankton dynamics in the presence and absence of treated wastewater effluent high in ammonium
Phytoplankton are critical component of the food web in most large rivers and estuaries, and thus identifying dominant controls on phytoplankton abundance and species composition is important to scientists, managers, and policymakers. Recent studies from a variety of systems indicate that ammonium ( NH+4) in treated wastewater effluent decreases primary production and alters phytoplankton species
Authors
Tamara E. C. Kraus, Kurt D. Carpenter, Brian A. Bergamaschi, Alexander Parker, Elizabeth B. Stumpner, Bryan D. Downing, Nicole Travis, Frances Wilkerson, Carol Kendall, Timothy Mussen
Using continuous underway isotope measurements to map water residence time in hydrodynamically complex tidal environments
Stable isotopes present in water (δ2H, δ18O) have been used extensively to evaluate hydrological processes on the basis of parameters such as evaporation, precipitation, mixing, and residence time. In estuarine aquatic habitats, residence time (τ) is a major driver of biogeochemical processes, affecting trophic subsidies and conditions in fish-spawning habitats. But τ is highly variable in estuari
Authors
Bryan D. Downing, Brian A. Bergamaschi, Carol Kendall, Tamara E. C. Kraus, Kate J. Dennis, Jeffery A. Carter, Travis von Dessonneck
Forecasting tidal marsh elevation and habitat change through fusion of Earth observations and a process model
Reducing uncertainty in data inputs at relevant spatial scales can improve tidal marsh forecasting models, and their usefulness in coastal climate change adaptation decisions. The Marsh Equilibrium Model (MEM), a one-dimensional mechanistic elevation model, incorporates feedbacks of organic and inorganic inputs to project elevations under sea-level rise scenarios. We tested the feasibility of deri
Authors
Kristin B. Byrd, Lisamarie Windham-Myers, Thomas Leeuw, Bryan D. Downing, James T. Morris, Matthew C. Ferner
Optical properties of dissolved organic matter (DOM): Effects of biological and photolytic degradation
Advances in spectroscopic techniques have led to an increase in the use of optical properties (absorbance and fluorescence) to assess dissolved organic matter (DOM) composition and infer sources and processing. However, little information is available to assess the impact of biological and photolytic processing on the optical properties of original DOM source materials. We measured changes in comm
Authors
Angela Hansen, Tamara E. C. Kraus, Brian Pellerin, Jacob Fleck, Bryan D. Downing, Brian A. Bergamaschi
High-resolution remote sensing of water quality in the San Francisco Bay-Delta Estuary
The San Francisco Bay–Delta Estuary watershed is a major source of freshwater for California and a profoundly human-impacted environment. The water quality monitoring that is critical to the management of this important water resource and ecosystem relies primarily on a system of fixed water-quality monitoring stations, but the limited spatial coverage often hinders understanding. Here, we show ho
Authors
Cédric G. Fichot, Bryan D. Downing, Brian A. Bergamaschi, Lisamarie Windham-Myers, Mark C. Marvin-DiPasquale, David R. Thompson, Michelle M. Gierach
Mississippi River nitrate loads from high frequency sensor measurements and regression-based load estimation
Accurately quantifying nitrate (NO3–) loading from the Mississippi River is important for predicting summer hypoxia in the Gulf of Mexico and targeting nutrient reduction within the basin. Loads have historically been modeled with regression-based techniques, but recent advances with high frequency NO3– sensors allowed us to evaluate model performance relative to measured loads in the lower Missis
Authors
Brian A. Pellerin, Brian A. Bergamaschi, Robert J. Gilliom, Charles G. Crawford, John Franco Saraceno, C. Paul Frederick, Bryan D. Downing, Jennifer C. Murphy
Experimental design and quality assurance: in situ fluorescence instrumentation
Both instrument design and capabilities of fluorescence spectroscopy have greatly advanced over the last several decades. Advancements include solid-state excitation sources, integration of fiber optic technology, highly sensitive multichannel detectors, rapid-scan monochromators, sensitive spectral correction techniques, and improve data manipulation software (Christian et al., 1981, Lochmuller a
Authors
Robyn N. Conmy, Carlos E. Del Castillo, Bryan D. Downing, Robert F. Chen
Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter
Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury
Authors
Jacob A. Fleck, Gary W. Gill, Brian A. Bergamaschi, Tamara E.C. Kraus, Bryan D. Downing, Charles N. Alpers
Groundwater contributions of flow, nitrate, and dissolved organic carbon to the lower San Joaquin River, California, 2006-08
The influence of groundwater on surface-water quality in the San Joaquin River, California, was examined for a 59-mile reach from the confluence with Salt Slough to Vernalis. The primary objective of this study was to quantify the rate of groundwater discharged to the lower San Joaquin River and the contribution of nitrate and dissolved organic carbon concentrations to the river. Multiple lines of
Authors
Celia Zamora, Randy A. Dahlgren, Charles R. Kratzer, Bryan D. Downing, Ann D. Russell, Peter D. Dileanis, Brian A. Bergamaschi, Steven P. Phillips