Publications by authors named "R D Gambrell"

COVID-19 vaccination rates remain lower among adolescents compared with adults. Youth participatory action research (YPAR) offers opportunities to inform youth vaccine communication at the local and population level. However, few studies have integrated systematic health communication research with YPAR.

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Coastal wetlands and estuaries are impacted by nutrient loads from a variety of sources including infrequently occupied hunting and fishing camps. The marshland upwelling system (MUS) was designed to treat wastewater in the coastal environment where traditional septic systems or centralized wastewater collection and treatment are not viable. A laboratory macrocosm study was designed to simulate field conditions in which domestic wastewater is treated via injection into a marsh subsurface.

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This study examined the influence of particle size and organic matter on aggregation and compaction of 3 hydraulically dredged sediments from coastal Louisiana (clay, silt loam, sandy loam) saturated under a range of salinity regimes (1 and 5 PSU, 5 and 10 PSU, and 15 and 25 PSU) for 4 time periods (1, 8, 16, and 26 weeks). Particle sizes were determined using a laser diffraction particle size analyzer, which allowed us to develop high-resolution results indicating changes in aggregate size across a spectrum of experimental conditions. The sediments with greater organic matter content exhibited approximately 60% aggregation, as indicated by fewer aggregates in the clay size fraction, and subsequently more aggregates in the sand size fraction, when organic matter remained in the sediment.

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The marshland upwelling system (MUS) utilizes the natural properties of wetland soils to treat domestic wastewater injected into the marsh subsurface as the wastewater moves upwards and outwards from the injection site. The system is different from coarse media based wetland treatment systems common in Europe, though it relies on the same principles. A laboratory study was designed to simulate field conditions in order to investigate and quantify the removal of nitrogen from the wastewater by pumping wastewater into the bottom of cores and observing the changes as the wastewater moved upward to the surface.

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Contaminated sediments provide the main source of mercury for methylation by bacteria in lakes and waterways. In situ capping has been used to remediate these sediments, but traditional reactive materials have very low affinity for Hg(II). This study investigated the mercury uptake by biogenic silica modified with L-cysteine, as a potential material to be used for in situ remediation technologies.

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