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1. Sink or break: Oil increases resistance of phytoplankton aggregates to fragmentation

   https://doi.org/10.1002/lol2.10454  

   Ziervogel, Kai; Sweet, Julia A; Song, Yixuan; Bretherton, Laura; Rau, Matthew J; Quigg, Antonietta; Passow, Uta (February 2025, Limnology and Oceanography Letters)

   Abstract Fragmentation of marine snow affects the downward flux of organic matter, and other aggregate‐associated compounds such as oil. Using phytoplankton aggregates, we demonstrate that marine snow with oil, termed marine oil snow, had a higher resistance to fragmentation compared to marine snow without oil when exposed to turbulence ex situ. At moderate shear levels, typical of the ocean mixed layer, 17% of marine snow without oil broke, whereas 63% of marine snow fragmented at intermediate shear. In contrast, only 17% and 33% of marine oil snow fragmented at the intermediate and highest shear levels, respectively. Our results suggest that oil increases the cohesion and stability of aggregates making them less susceptible to breaking. This work contributes toward explaining the exceptional oil sedimentation event following the 2010 spill in Gulf of Mexico. It also enhances our understanding of the factors that determine the probability of sinking aggregates to fragment. 

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2. Bacterial response to the 2021 Orange County, California, oil spill was episodic but subtle relative to natural fluctuations

   https://doi.org/10.1128/spectrum.02267-24  

   Brock, Melissa L; Tavares-Reager, Joana F; Dong, Jialin; Larkin, Alyse A; Lam, Toan; Pineda, Nataly; Olivares, Christopher I; Mackey, Katherine_R M; Martiny, Adam C (May 2025, Microbiology Spectrum)

   Steven, Blaire (Ed.)

   ABSTRACT An oil spill began in October 2021 off the coast of Orange County, California, releasing 24,696 gallons of crude oil into coastal environments. Although oil spills, such as this one, are recurrent accidents along the California coast, no prior studies have been performed to examine the severity of the local bacterial response. A coastal 10-year time series of short-read metagenomes located within the impacted area allowed us to quantify the magnitude and duration of the disturbance relative to natural fluctuations. We found that the largest change in bacterial beta-diversity occurred at the end of October. The change in taxonomic beta-diversity corresponded with an increase in the sulfur-oxidizing cladeCandidatusThioglobus, an increase in the total relative abundance of potential hydrocarbon-degrading bacteria, and an anomalous decline in the picocyanobacteriaSynechococcus. Similarly, changes in function were related to anomalous declines in photosynthetic pathways and anomalous increases in sulfur metabolism pathways as well as aromatic degradation pathways. There was a lagged response in taxonomy and function to peaks in total PAHs. One week after peaks in total PAH concentrations, the largest shifts in taxonomy were observed, and 1 week after the taxonomy shifts were observed, unique functional changes were seen. This response pattern was observed twice during our sampling period, corresponding with the combined effect of resuspended PAHs and increased nutrient concentrations due to physical transport events. Thus, the impact of the spill on bacterial communities was temporally extended and demonstrates the need for continued monitoring for longer than 3 months after initial oil exposure.IMPORTANCEOil spills are common occurrences in waterways, releasing contaminants into the aquatic environment that persist for long periods of time. Bacterial communities are rapid responders to environmental disturbances, such as oil spills. Within bacterial communities, some members will be susceptible to the disturbance caused by crude oil components and will decline in abundance, whereas others will be opportunistic and will be able to use crude oil components for their metabolism. In many cases, when an oil spill occurs, it is difficult to assess the oil spill’s impact because no samples were collected prior to the accident. Here, we examined the bacterial response to the 2021 Orange County oil spill using a 10-year time series that lies within the impacted area. The results presented here are significant because (i) susceptible and opportunistic taxa to oil spills within the coastal California environment are identified and (ii) the magnitude and duration of thein situbacterial response is quantified for the first time. 

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3. Essential oil content of Rhododendron tomentosum responds strongly to manipulation of ecosystem resources in Arctic Alaska

   https://doi.org/10.1139/as-2020-0055  

   Baldwin, Tracey A.; Oberbauer, Steven F. (September 2022, Arctic Science)

   The essential oils of the widely distributed boreal/Arctic dwarf shrub, Rhododendron tomentosum ssp. subarcticum (Harmaja) G.D. Wallace, have important ecological, cultural, medicinal, and commercial roles. To understand the relationship between resource limitation and essential oil content of this species we measured the amount and diversity of terpenes from shoots of plants exposed to a 14-year ecosystem resource manipulation experiment in Arctic Alaska. Treatments tested interactive effects of nitrogen (N) and phosphorus (P) addition, warming and N + P fertilization, and shading and N + P fertilization. The controls and NP fertilization had the highest essential oil content, whereas shading and P addition had less than 20% of the control content. Warming reduced essential oil content to <65% of that of the controls. Essential oil components varied greatly among the treatments, with significant differences in the expression of specific essential oil components. Large changes in plant community composition and ecosystem structure in response to treatments likely played a large role in the response of R. tomentosum. Our data suggest that resource changes in response to climate warming and its secondary effects on light and nutrient availability have the potential to change the profiles of essential oils in R. tomentosum, with important ecological and cultural impacts. 

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4. Experimental Study to Investigate CO2 Mediated Oil Flow in Nanopores

   https://doi.org/10.2118/220726-MS  

   Hegazy, D A; Yin, X; Qiao, R; Ozkan, E (September 2024, SPE)

   Abstract To optimize CO2 EOR operations, such as Huff and Puff (HnP), it is necessary to have a good understanding of oil- CO2 transport both at nanopore and at reservoir scales. In this study, experiments were performed to investigate how pore adsorbed CO2 can mediate oil flow in analog nanopore arrays. These experiments quantified how much interfacial CO2 contributed to improving permeability to oil in nanopores, in addition to increasing mobility by viscosity reduction. The experimental procedure involved flowing C10 (decane) with and without CO2 through an Anodic Aluminum Oxide (AAO) membrane at a defined differential pressure and recording flow rate. Viscosity obtained from correlations was then used to calculate membrane pore permeability. Inlet pump pressure was lower than the oil-CO2 miscibility pressure at the test conditions. Pore permeability improvement due to pore wall adsorbed CO2 was computed by isolating the effect of viscosity reduction of the bulk fluid. An overall pore-permeability increase of 15% was observed in the CO2 and C10 mixture experiments compared to the C10-only experiments, due to interfacial CO2. These results lend support to the previous molecular dynamics simulations, which predicted that interfacial CO2 can significantly modulate C10 flow in nanopores up to 10 nm diameter (Moh et al. 2020). Some differences from the molecular dynamics simulations of Moh et al. (2020) observed in the experimental study also verify the potential contribution of other phenomena to the permeability enhancement of the nanoporous membrane in the presence of CO2. Therefore, this study provides further impetus for exploring the unique nanofluidic physics of oil and CO2 transport arising from CO2 at oil-wall interfaces. The demonstrated significance of the unique nanopore phenomena, which have not been observed and incorporated into large-scale flow models, emphasizes the importance of identifying and incorporating nanofluidic physics into commercial reservoir simulators' transport models for better representation of CO2 and oil flow in unconventional reservoirs. 

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5. Research Outreach Interdisciplinary Activity to classify olive oil blends integrating multicolor imaging, image processing, and machine learning

   Abraham, Allan; Balachandran, Kameshwaran; Doblas, Ana (November 2023, Undergraduate Research Journal)

   This outreach undergraduate research project presents a low-cost method to distinguish the quality of different olive oils. The proposed method is based on an indirect measurement of the chlorophyll molecules present when a green laser diode illuminates the oil sample. Oil blends can be classified into five classes (no olive oil, light olive oil, medium olive oil, olive oil, and extra virgin olive oil) by quantifying the ratio of the red channel versus the green channel along the laser illumination path from a color image. After labeling each oil blend, a convolutional neural network has been implemented and trained to automatically classify oil blends from a color image. The trained convolutional neural network has an accuracy of 90% in identifying and categorizing oil blends. This undergraduate research project introduces students to an interdisciplinary application requiring the combination of optical spectroscopy (i.e., multicolor imaging), image processing, and machine learning. In addition, due to the simplicity of the optical apparatus and computational analysis, high school students could implement and validate their own costeffective oil-quality classification device. 

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