S. Borglin

ABSTRACT Background/Question/Methods Agricultural production in arid regions results in large-scale modifications of landscape and hydrology, causing disruption of natural ecosystem function. Drainage from irrigated agriculture results in nutrient enrichment and the eutrophication of impacted rivers. In the Central Valley of California, the most productive arid farming region in the world, eutrophication of the San Joaquin River results in the export of phytoplankton biomass to the estuary, which creates regional anoxic conditions, negatively impacting fisheries. Fundamental information concerning factors influencing phytoplankton growth rates and yields is needed to understand, and ultimately control, eutrophication in this ecosystem. In this study we tested the hypothesis that alteration in regulated river flows, planned as part of various restoration activities, would alter phytoplankton growth rates and yields and therefore exports of phytoplankton from the river to the estuary. Under experiments directed at predicting unintended outcomes from future restoration activities, river flow regimes were modified and phytoplankton response was measured using continuous chlorophyll monitoring and other methods. Direct measurement of phytoplankton growth kinetics were then used to inform and confirm predictions made by water quality and hydrologic models concerning the mass loading of phytoplankton to the estuary. In this study, sondes were used to measure chlorophyll in the river and tributaries with high spatial and temporal resolution. Chlorophyll measurements were complemented with grab sampling determination of nutrients and other factors of significance to phytoplankton metabolism. This data was combined with hydrologic data to allow in-situ measurement of growth rates and yields. Results/Conclusions Results indicate that that hydrologic factors are the major influences on observed phytoplankton growth rates and biomass yields (nutrients and light being typically in excess). It was found that direct measurement of phytoplankton growth kinetics could be used to document changes in river eutrophication and water quality as planned ecosystem restoration activities are implemented. The results of these studies and the role of continuous data in the development of ecosystem restoration will be discussed.

Traditional water quality monitoring programs directed at non-point source (NPS) pollution typically involve the collection of grab sample data at a fixed location and a routine time interval with the objective of identifying areas of degraded water quality. The frequency and locations of measurement are often determined by regulatory concerns, rather than based on a scientific analysis, and it is

The State of California is instituting a total maximum daily load (TMDL) requirement for oxygen demand on the San Joaquin River (SJR) in Central California that includes algal biomass. The TMDL is driven by the low levels of dissolved oxygen in the Stockton deep water ship channel which is a barrier to fish migration to the upstream SJR. Previous studies

In the United States, environmentally impaired rivers are subject to regulation under total maximum daily load (TMDL) regulations that specify watershed wide water quality standards. In California, the setting of TMDL standards is accompanied by the development of scientific and management plans directed at achieving specific water quality objectives. The San Joaquin River (SJR) in the Central Valley of California now has a TMDL for dissolved oxygen (DO). Low DO conditions in the SJR are caused in part by excessive phytoplankton growth (eutrophication) in the shallow, upstream portion of the river that create oxygen demand in the deeper estuary. This paper reports on scientific studies that were conducted to develop a mass balance on nutrients and phytoplankton in the SJR. A mass balance model was developed using WARMF, a model specifically designed for use in TMDL management applications. It was demonstrated that phytoplankton biomass accumulates rapidly in a 88 km reach where plan...

Recent work has demonstrated that both the adsorption and desorption of hydrophobic organic chemicals to sediments and soils can be quite slow and that chemical equilibrium may not be a good approximation in many real situations. By means of long‒term batch experiments, this has been recently and clearly shown for the adsorption of hexachlorobenzene and three polychlorinated biphenyls to suspended sediments. In the present study, long‒term desorption experiments are performed with three hydrophobic organic chemicals (hexachlorobenzene and two polychlorinated biphenyls) and suspended sediments. Desorption times are on the order of a month to several years. It is shown that the desorption rates are dependent on the particle/floc size and density distributions, the type of water, the amount of organic carbon in the sediments, the time of adsorption before desorption, and the chemical partition coefficient. It is also shown that a simple chemical diffusion model with an effective diffus...

... Interim Report No. 1 September 8, 2005 William Stringfellow 1,3 Sharon Borglin 1,3 Jeremy Hanlon 1 ... Lara Sparks 21 Orestimba Creek at River Road 37.41396 -121.01488 Del Puerto WDLiz Vonckx 22 Modesto ID Lateral 4 37.63057 -121.15888 Modesto ID Michael Niemi ...

• The 2004-2008 field experiment at the Hanford 100-H Site showed that a single injection of the hydrogen release compound (HRC)—a slow release glycerol polylactate—into groundwater stimulated an increase in biomass and a depletion of terminal electron acceptors, ...

Determining the transient chemical properties of the intracellular environment can elucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms that enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier transform infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bond structures in their cellular water. We observed a sequence of well orchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses.

Tropical forest soils decompose litter rapidly with frequent episodes of anoxic conditions, making it likely that bacteria using alternate terminal electron acceptors (TEAs) play a large role in decomposition. This makes these soils useful templates for improving biofuel production. To investigate how TEAs affect decomposition, we cultivated feedstock-adapted consortia (FACs) derived from two tropical forest soils collected from the ends of a rainfall gradient: organic matter-rich tropical cloud forest (CF) soils, which experience sustained low redox, and iron-rich tropical rain forest (RF) soils, which experience rapidly fluctuating redox. Communities were anaerobically passed through three transfers of 10 weeks each with switchgrass as a sole carbon (C) source; FACs were then amended with nitrate, sulfate, or iron oxide. C mineralization and cellulase activities were higher in CF-FACs than in RF-FACs. Pyrosequencing of the small-subunit rRNA revealed members of the Firmicutes , Ba...

ABSTRACT The primary contaminant of concern in groundwater at the DOE Hanford 100 Area (Washington State) is hexavalent chromium [Cr(VI)] in Hanford coarse-grained sediments. Three lactate injections were conducted in March, August, and October 2010 at the Hanford 100-H field site to assess the efficacy of in situ Cr(VI) bioreductive immobilization. Each time, 55 gal of lactate solution was injected into the Hanford aquifer. To characterize the biogeochemical regimes before and after electron donor injection, we implemented a comprehensive plan of groundwater sampling for microbial, geochemical, and isotopic analyses. These tests were performed to provide evidence of transformation of toxic and soluble Cr(VI) into less toxic and poorly soluble Cr(III) by bioimmobilization, and to quantify critical and interrelated microbial metabolic and geochemical mechanisms affecting chromium in situ reductive immobilization and the long-term sustainability of chromium bioremediation. The results of lactate injections were compared with data from two groundwater biostimulation tests that were conducted in 2004 and 2008 by injecting Hydrogen Release Compound (HRC°), a slow-release glycerol polylactate, into the Hanford aquifer. In all HRC and lactate injection tests, 13C-labeled lactate was added to the injected solutions to track post-injection carbon pathways. Monitoring showed that despite a very low initial total microbial density (from <104 to 105 cells/mL), both HRC and lactate injections stimulated anaerobic microbial activity, which led to an increase in biomass to >107 cells/mL (including sulfate- and nitrate-reducing bacteria), resulting in a significant decrease in soluble Cr(VI) concentrations to below the MCL. In all tests, lactate was consumed nearly completely within the first week, much faster than HRC. Modeling of biogeochemical and isotope fractionation processes with the reaction-transport code TOUGHREACT captured the biodegradation of lactate, fermentative production of acetate and propionate, the evolution of 13C in bicarbonate, and the rate of sulfate reduction. In contrast to the slow-release HRC injections, no long-term effects of biostimulation and Cr bioreduction were observed in groundwater after the lactate injections. The presentation will address these patterns of the geochemical, δ13C of DIC, and biomass changes in groundwater before and after the polylactate and lactate injections.

Tracer tests and field monitoring before, during, and after bio-immobilization of Cr(VI) in groundwater at the Hanford 100H field site have provided key data constraining the geohydrology and biogeochemistry of field- scale bioreduction. A slow release polylactate, Hydrogen Release Compound (HRC), was used to stimulate the in situ bioreduction and removal of Cr(VI) from groundwater. Monitoring included an extensive suite

To demonstrate the feasibility of a cost-effective field-scale bioimmobilization of Cr(VI) in contaminated groundwater, using a slow release polylactate, Hydrogen Release Compound (HRCTM), we have conducted a pilot study at the Hanford 100H field site. To assess the pre- and post-injection test groundwater conditions, we used an integrated monitoring approach, involving hydraulic, geochemical, microbial, and geophysical techniques and analytical methods,

Diving into Deep Water The Deepwater Horizon oil spill in the Gulf of Mexico was one of the largest oil spills on record. Its setting at the bottom of the sea floor posed an unanticipated risk as substantial amounts of hydrocarbons leaked into the deepwater column. Three separate cruises identified and sampled deep underwater hydrocarbon plumes that existed in May and June, 2010—before the well head was ultimately sealed. Camilli et al. (p. 201 ; published online 19 August) used an automated underwater vehicle to assess the dimensions of a stabilized, diffuse underwater plume of oil that was 22 miles long and estimated the daily quantity of oil released from the well, based on the concentration and dimensions of the plume. Hazen et al. (p. 204 ; published online 26 August) also observed an underwater plume at the same depth and found that hydrocarbon-degrading bacteria were enriched in the plume and were breaking down some parts of the oil. Finally, Valentine et al. (p. 208 ; publis...