George Bennett
Science and Products
Sources, bioavailability, and photoreactivity of dissolved organic carbon in the Sacramento-San Joaquin River Delta
We analyzed bioavailability, photoreactivity, fluorescence, and isotopic composition of dissolved organic carbon (DOC) collected at 13 stations in the Sacramento-San Joaquin River Delta during various seasons to estimate the persistence of DOC from diverse shallow water habitat sources. Prospective large-scale wetland restorations in the Delta may...
Stepanauskas, R.; Moran, M.A.; Bergamaschi, B.A.; Hollibaugh, J.T. Suspended sediment fluxes in a tidal wetland: Measurement, controlling factors, and error analysis
Suspended sediment fluxes to and from tidal wetlands are of increasing concern because of habitat restoration efforts, wetland sustainability as sea level rises, and potential contaminant accumulation. We measured water and sediment fluxes through two channels on Browns Island, at the landward end of San Francisco Bay, United States, to determine...
Ganju, N.K.; Schoellhamer, D.H.; Bergamaschi, B.A. Quantifying the contributions of tidal wetlands to dissolved organic material in the San Francisco Estuary, California, USA
Bergamaschi, B.A.; Downing, B.A; Wheeler, G.A; Schoellhamer, D.H.; Ganju, N.; Fram, M.S.; Erickson, D.E.; Kendall, C.; Bemis, B.E.; Stepanauskas, R.; Hollibaugh, J.T.; Fujii, R. Preliminary assessment of DOC and THM precursor loads from a freshwater restored wetland, an agricultural field, and a tidal wetland in the Sacramento-San Joaquin River Delta
Water exported from the Sacramento-San Joaquin River Delta supplies drinking water to more than 22 million people in California. At certain times of the year, Delta waters contain relatively high concentrations of dissolved organic carbon (DOC) and bromide. During these times, chlorination of Delta water for drinking water disinfection will form...
Fujii, R.; Bergamaschi, B.A.; Ganju, N.K.; Fleck, J.A.; Burow-Fogg, K.R.; Schoellhamer, D.; Deverel, S.J. Covariance of bacterioplankton composition and environmental variables in a temperate delta system
We examined seasonal and spatial variation in bacterioplankton composition in the Sacramento-San Joaquin River Delta (CA) using terminal restriction fragment length polymorphism (T-RFLP) analysis. Cloned 16S rRNA genes from this system were used for putative identification of taxa dominating the T-RFLP profiles. Both cloning and T-RFLP analysis...
Stepanauskas, R.; Moran, M.A.; Bergamaschi, B.A.; Hollibaugh, J.T. Evaluation of specific ultraviolet absorbance as an indicator of the chemical composition and reactivity of dissolved organic carbon
Specific UV absorbance (SUVA) is defined as the UV absorbance of a water sample at a given wavelength normalized for dissolved organic carbon (DOC) concentration. Our data indicate that SUVA, determined at 254 nm, is strongly correlated with percent aromaticity as determined by 13C NMR for 13 organic matter isolates obtained from a variety of...
Weishaar, J.L.; Aiken, George R.; Bergamaschi, Brian A.; Fram, Miranda S.; Fujii, Roger; Mopper, K.
Improving water quality in Sweetwater Reservoir, San Diego County, California; sources and mitigation strategies for trihalomethane (THM)-forming carb
Fram, M.S.; Bergamaschi, B.A.; Fujii, Roger Pesticides associated with suspended sediments entering San Francisco Bay following the first major storm of water year 1996
Estuaries receive large quantities of suspended sediments following the first major storm of the water year. The first-flush events transport the majority of suspended sediments in any given year, and because of their relative freshness in the hydrologic system, these sediments may carry a significant amount of the sediment-associated pesticide...
Bergamaschi, Brian; Kuivila, Kathryn; Fram, Miranda S. Tannin diagenesis in mangrove leaves from a tropical estuary: A novel molecular approach
Molecular-level condensed tannin analyses were conducted on a series of mangrove (Rhizophora mangle) leaves at various stages of decomposition in a tropical estuary. Total molecular tannin yields ranged from 0.5% ash-free dry weight (AFDW) in the most highly degraded black leaves (6-7 weeks in the water) up to >7% AFDW in fresh leaves (<1...
Hernes, P.J.; Benner, R.; Cowie, G.L.; Goi, M.A.; Bergamaschi, B.A.; Hedges, J. I. Trihalomethanes formed from natural organic matter isolates: Using isotopic and compositional data to help understand sources
Over 20 million people drink water from the Sacramento-San Joaquin Delta despite problematic levels of natural organic matter (NOM) and bromide in Delta water, which can form trihalomethanes (THMs) during the treatment process. It is widely believed that NOM released from Delta peat islands is a substantial contributor to the pool of THM...
Bergamaschi, Brian A.; Fram, Miranda S.; Fujii, Roger; Aiken, George R.; Kendall, Carol; Silva, Steven R. Carbon isotopic constraints on the contribution of plant material to the natural precursors of trihalomethanes
The δ13C values of individual trihalomethanes (THM) formed on reaction of chlorine with dissolved organic carbon (DOC) leached from maize (corn; Zea maize L.) and Scirpus acutus(an aquatic bulrush), and with DOC extracted from agricultural drainage waters were determined using purge and trap introduction into a gas...
Bergamaschi, B.A.; Fram, M.S.; Kendall, C.; Silva, S.R.; Aiken, G.R.; Fujii, R. Determination of pesticides associated with suspended sediments in the San Joaquin River, California, USA, using gas chromatography-ion trap mass spectrometry
An analytical method useful for the quantification of a range of pesticides and pesticide degradation products associated with suspended sediments was developed by testing a variety of extraction and cleanup schemes. The final extraction and cleanup methods chosen for use are suitable for the quantification of the listed pesticides using gas...
Bergamaschi, B.A.; Baston, D.S.; Crepeau, K.L.; Kuivila, K.M.