OREGON STATE UNIVERSITY
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Summer Research Internships for Undergraduates
Reconstructing the 1700 tsunami flow to improve hazard maps on the Oregon coastTsunamis and earthquakes pose a significant threat to Pacific Northwest communities. It is important to understand how tsunamis, and the earthquakes that create them, function so we can protect infrastructure and limit fatalities. In our study, we plan to collect marsh cores at Alsea Bay and correlate the spatial extent of the tsunami sediment deposits to predictions of tsunami sediment deposits from the numerical tsunami inundation models SCHISM and Delft3D. We can then compare these numerical flow models to Cascadia Subduction Zone rupture models in order to understand the fault zone rupture pattern. Using these models, we hope to improve the Alsea Bay tsunami hazard map and create a prototype to improve tsunami hazard maps along the entire Oregon coast.
Analysis of upper ocean surface wave structure in the Bay of Bengal using χSOLO floatsSurface waves play a vital role in air-sea interactions, and being able to easily measure them in situ is of value for validation and improvement of predictive models. Here we diagnose surface wave properties in the Bay of Bengal using modified vertical SOLO II profiling floats, which are regularly used as part of the Argo float array. The modified χSOLO floats measured high frequency pressure, acceleration, velocity fluctuations, and turbulence data, in additional to traditional conductivity-temperature-depth data. The pressure and acceleration data were used to compute surface wave period and height for wind waves and distantly generated swells. The period of the swells was computed using power spectral density of vertical acceleration at the bottom of a vertical dive, and surface wind wave period was computed using power spectral density of the pressure record while at the surface. The height of the waves was computed using a curve fit of the decay of the Fourier components of the horizontal acceleration with depth. This was chosen over fitting to the exponential decay of the time series since the time series fit does not easily track multiple frequencies. These methods unveiled a series of swells of roughly half meter amplitude generated between 7000km and 9500km away and two surface wind wave bands of period _ 4s and _ 7s with amplitudes 0.1m and 0.3m respectively. The observed waves agreed well with model predictions from the global WaveWatch III simulations.
Remote sensing of surf zone waves from an unmanned aerial vehicle (UAV): Bathymetry inversion using multiple geophysical variablesMeasurements of bathymetry and waves are critical for understanding of the nearshore environment as a whole, but are difficult and costly to obtain in situ. This research is specifically focused on using a commercial off-the-shelf UAV (Unmanned Aerial Vehicle), for gathering wave data, with applications to determining bathymetry. The data consists of high altitude video to measure wave celerity, LiDAR (Light Detection and Ranging) mounted on the UAV to measure water surface elevation, and stereoscopic imaging (using two UAVs) to map wave shape. Data was collected at Gleneden Beach, near Newport, OR. The data was used for bathymetry identification, by inverting three separate models for (i) wave celerity, (ii) wave breaking dissipation, and (iii) depth-limited breaker height. An existing algorithm, cBathy (Holman et al., 2013), was also used to estimate bathymetry from video data. Bathymetry inversions are not always consistent amongst the three methods; we discuss possible reasons and implications for the disagreements.
Variation in eroded material and accumulation of Columbia River sediments off the Oregon continental margin since the Last Glacial MaximumThe advance and retreat of the Cordilleran ice sheet during the late Pleistocene shaped the modern Columbia River basin, with multiple catastrophic flood events from glacial Lake Missoula significantly influencing regional sediment transport and accumulation on the Washington/Oregon continental margin. Likewise, general melting of the Cordilleran ice sheet supplied additional sediment to the river and continental margin, resulting in significant changes to its regional erosional history, flood events, and sediment accumulation from the Last Glacial Maximum (LGM, ~26-19 ka) to the present. To investigate this past variability, sediment cores were collected from the Columbia River continental margin during coring cruise OC1706B on the R/V Oceanus in 2017. Two sites, one on a bathymetric rise near the Willapa Canyon submarine fan (02JC) and another on the upper continental slope south of Astoria Canyon (06JC), were selected for core-scanning X-ray fluorescence (XRF) analysis at 0.2 mm resolution. Sediment elemental ratios in the cores point towards at least three distinct chemostratigraphic units that may correspond to changes in sediment provenance and erosional activity of the Columbia River basin. The oldest material, deposited as a series of gravity flows, suggests a geochemically mafic source, and transitions to a felsic source prior to the onset of the Holocene regime. Further geochemical analysis of source samples collected throughout the Columbia River basin, as well as the development of a higher-resolution chronology, will help constrain past changes in provenance of sediments that have accumulated in the offshore environment.
Cross-channel currents near curves in the Hudson River and North River estuaries: the influence of river discharge and tidal amplitude on flow dynamicsAlthough cross-channel currents in estuaries are weaker than along-channel flows, they can have an important influence on along-channel momentum, dispersion, and sediment transport. We examined cross-channel currents near curves in the Hudson River and North River estuaries, characterizing the influence of river discharge, tidal amplitude, and resulting variation in salinity stratification on the patterns and strength of cross-channel circulation. Using previously collected data on currents, pressure, and bottom and surface salinity from instruments deployed at four sites in the Hudson River and two cross-channel arrays in the North River, along with data on river discharge from the USGS, we found that trends in stratification closely followed the spring-neap cycle, with higher stratification during neap tides and lower stratification during spring tides. High discharge was also associated with higher stratification, and discharge had a stronger influence on dynamics in the North River than in the Hudson. These trends in stratification led to strong, well-defined two-layer patterns of cross-channel flow during spring tides, with weaker two- and three-layer patterns during neap tides. The most distinct and strongest currents generally occurred during flood tide in the Hudson, with more variability in the North River, and current patterns demonstrated forcing from both rotation and curvature, with the importance of each term varying by location. Using a simplified momentum budget, we were able to accurately predict the observed cross-channel flows in the Hudson during both spring and neap conditions. However, the approximation only explained cross-channel flows for relatively simple patterns in vertical shear, indicating the need for additional forcing terms, such as advection and baroclinic pressure gradients, to explain more complex profiles. A better understanding of cross-channel currents contributes to our knowledge of estuarine dynamics as well as restoration and management efforts.
The role of the organic matrix in larval C. gigas shell developmentLarval and adult Pacific oysters (Crassostrea gigas) precipitate their calcium carbonate shells at different rates; larval shell development occurs much more rapidly, with the initial shell precipitated during prodissoconch I being the fastest. The mechanisms that facilitate such different growth rates are not well understood. We hypothesize that the differences in mineralization rates are due to functional differences in the organic matrices of the shells, corresponding to their respective life stages. The organic matrix was isolated by decalcifying larval and adult oyster shells with a chelating agent. Measurements showed that we were successful in removing inorganic shell material from the matrix. We then measured rates of calcium carbonate precipitation onto the matrices, as well as other substrates (oyster and clam shell, glass biobeads) in artificial seawater (ASW) with a target aragonite saturation state (Ωarg) of ~5.50. Changes in calcium and alkalinity concentrations of the ASW were measured during precipitation experiments to determine calcification rates. Samples of isolated matrix were collected for C/N analysis to estimate differences in protein content. Our initial trials using ASW without magnesium were unsuccessful due to spontaneous precipitation. Several methodological challenges were resolved through the course of the experiments. Later trials using commercially available aquarium sea salts and ASW containing magnesium were both successful in facilitating precipitation onto shell material. Preliminary results show differences in precipitation rates with the various calcification seeds.
Investigating the influence of green infrastructure on air temperature in Portland, OregonUrban green infrastructure (GI) has important roles in microclimate variation, but the reasons for Ta variation, the magnitude of these changes, and the interaction between multiple co-benefits of GI, remain less certain. To examine the influences of urban vegetation on air temperature (Ta) in Portland, Oregon, 24 TidbiT temperature loggers were deployed 2.5 meters high on green and grey streets (classified by the presence or absence of GI) and recorded temperatures every 15 minutes from June 28 to July 27, 2017. 12 TidbiTs were deployed in the following green street locations: 8 in SW 12th Avenue Green Street bioswales, 2 in Portland State University bioswales between Cramer Hall and the Memorial Union, and 2 in South Park Blocks. 12 TidbiTs were deployed in the following grey streets: 5 south of SW 12th Avenue Green Street, 6 on SW Montgomery before the intersection with SW 12th Avenue, and 1 on SW Market Street. Maximum daily temperatures for green street sensors averaged 30.l ºC, while grey streets averaged 32.2 ºC and on an average day. Sun exposure on grey streets was consistently higher than green street locations, supported by the 46% difference of vegetation coverage within a 10-meter radius. Four classifications (park blocks, bioswales, community garden, grey street) based on similar GI features show the need for specification of the term ‘green infrastructure’, since the bioswale and park block green street locations showed significantly different average temperatures (p<0.01).
Magnetotelluric investigations of the Yellowstone Caldera: understanding the emplacement of crustal magma bodiesWideband magnetotellurics (MT) presents an ideal method for imaging conductive shallow magma bodies associated with contemporary Yellowstone-Snake River Plain (YSRP) magmatism. Particularly, how do these magma bodies accumulate in the mid to upper crust underlying the Yellowstone Caldera, and furthermore, what role do hydrothermal fluids play in their ascent? During the summer 2017 field season, two field teams from Oregon State University and the University of Wisconsin-Madison installed forty-four wideband MT stations within and around the caldera, and using data slated for joint 3-D inversion with existing seismic data, two 2-D vertical conductivity sections of the crust and upper mantle were constructed. These models, in turn, provide preliminary insight into the emplacement of crustal magma bodies and hydrothermal processes in the YSRP region.
Modeling tsunami from rupture scenarios along the Cascadia Subduction ZoneNew modeling the Cascadia Subduction zone allows for the comparison of the variety of different proposed models intended to identify the potential rupture scenarios for the 1700 earthquake. We will use the model to constrain the rupture scenario such that it correlates to subsidence data and tsunami deposits from the region. Constraining the data better allows us to establish likely rupture scenarios, which in turn enables us to better prepare coastal communities for the earthquake and resulting tsunami. We intend to use ArcGIS to map the fault, add a mesh grid in another program, and model deformation from different rupture scenarios in a 3-D elastic halfspace. ArcGIS enables us to correctly map the geometry of the subduction zone, while the mesh grid permits us to change slip variables along the fault, while elastic half space allows us to model both the elastic deformation resulting from the different models.
Isotopic signatures and elemental ratios of heavy metals in moss along a mining haul road in NW Alaska using Pb, In, and Bi Red Dog Mine is one of the world’s largest producers of zinc (Zn) concentrate. Elevated concentrations of lead (Pb), zinc (Zn), and cadmium (Cd) in Hylocomium splendens moss samples have been documented along the mine’s haul road that traverses 32 km of northwestern Alaskan tundra within Cape Krusenstern National Monument (Neitlich et al. 2017). The elevated metal concentrations have been attributed to the transport of ore along the haul road from the mine to the port. This project builds on this earlier study by analyzing the Pb isotopic compositions of that study’s moss samples to explore how isotopic signatures changed as a function of distance from the road. In addition, it examines the concentrations of the ore trace constituents indium (In) and bismuth (Bi) to provide additional evidence for source. The trend formed by the isotopic ratios of Pb in moss samples suggests mixing between two endmember Pb compositions. The most radiogenic isotopic compositions were measured in moss collected very close to the haul road and the least radiogenic in moss collected from the most southern sites, 40–60 km from the haul road. The Pb isotopic signatures of moss samples at very close distances from the haul road diverged slightly from the predicted field of ratios based upon previously published Pb isotopic compositions for Zn and Pb ores from the mine. This may be explained by the mixing of both Pb and Zn concentrate dusts in the environment. The presence of In and Bi in higher concentrations from samples near the road points could be due to the dispersion of concentrate dusts in the national monument. In contrast to the observed natural In and Bi concentrations of about 1 ppb and 8 ppb and the samples closest to the road showed In and Bi as high as 40 ppb and 120 ppb, respectively. By combining the use of Pb isotopes with elemental analysis of In and Bi we provide a potential method of ore identification while furthering the extent biomonitoring with H. splendens. This study also facilitates future research of Pb sources in the Noatak National Preserve (NNP) east of the mine by identifying the sources of contamination and furthering the extent of its impact in the region by means of biomonitoring with H. splendens.
Evaluating moss as biomonitors of heavy metal deposition using hierarchal sampling and rain leaching experimentsHeavy metal pollution is of increasing concern across the globe. Moss can be used as a biomonitor to estimate atmospheric heavy metal concentrations. However, much remains unknown about the relationship between metal content in moss tissues and atmospheric concentration. Using metal concentrations in moss to map the spatial distribution of metal deposition depends on a thorough understanding of the spatial and temporal variability within a moss sample and among samples. Physiology, precipitation events and rates, and other environmental conditions contribute to metal accumulation rates and spatial variability of metal concentrations in moss plants in the same vicinity. Quantifying and understanding spatial variability is vital to the use of moss as biomonitors. A hierarchical sampling method was used to model spatial variation of heavy metal content in a terrestrial epiphytic moss, Orthotrichum lyellii. Four samples were collected from each of four trees at several sites in Oregon representing an unpolluted site, urban sites, and a parkland site downwind of Portland. The moss was acid digested and analyzed by ICP-MS for Pb, Cd, and Zn concentrations. The results indicate high variation in metal concentrations among samples at a tree, among trees at a site, and among sites. A rain leaching experiment was also used to assess how precipitation affects loss of Cd in the three cellular compartments of O. lyellii tissues. Moss tissue consists of the inter-, extra-, and intracellular compartments, each with different rates of uptake and loss of trace elements. Moss samples were subjected to an artificial rain solution of 0.01 M CaCl2 for 15, 30, 60, and 120 minutes using a gravity-fed rain device. A sequential elution procedure was used to quantify the metal concentrations in each cellular compartment. Comparing the pre-rain and post-rain moss tissue concentrations indicate loss of Cd from the extracellular compartments after all rains. Total Cd concentration decreased after rains, with the greatest loss after the short rain of 15 minutes.
The changing sand content on the Columbia Margin over the 20th century: Implications for wave climateWave height as measured by National Oceanic and Atmospheric Administration (NOAA) buoys on the Washington/Oregon coast suggests that wave climate has been increasing on this margin since at least 1976. This change in wave climate has been held responsible for coastal erosion, causing negative economic impacts within this area. However, it remains unknown as to whether or not this decadal-scale increase in wave climate is a recent phenomenon or part of a longer-term trend or cycle. Using sediments collected by the RV/Oceanus during cruise OC1706B we evaluated if the significant increase in wave height observed on the Washington/Oregon coast was reflected in the accumulation of sediment on the continental shelf and if so, whether we can extend our understanding of wave climate using the sediment record. Our study focuses on three cores from two sites: 04MC/05GC are located on the shelf just north of the Columbia River at 80, while site 08MC is located south of the Columbia River on the southern lobe of the Columbia littoral cell. The texture of these cores was determined from grain size analysis using sieves to establish the >63 m (sand) weight fraction and a Coulter counter to look at silt/clay grain size distributions, while composition of core 04MC was assessed using an ITRAX XRF core scanner. An initial age model provided by the 210Pb-based accumulation rates for the Columbia margin published in Nittrouer et al, 1976. Mass percentage of sand increased in all three cores between ~1975 and 2016, consistent with increasing depositional energy or a coarsening sediment supply over this time interval. Sediment composition as determined from XRF elemental ratios in core 04MC show no significant correlation with the recent increase in grain size. The longer records provided by cores 05GC and 08MC show that the change in grain sizes are not monotonic, but rather show that sediment textures were anomalously fine between approximately 1975 and 2000 interval, prior to which grain sizes were approximately similar to today. If these changes do indeed reflect depositional energy, it appears the recent increase in wave climate may not be unprecedented in the past century.
Columbia River flood events at the end of the last Ice AgeMegafloods emanating from the Columbia River drainage basin into the northeast Pacific during the end of the last ice age may provide an extreme example of focused freshwater flux to the ocean in the recent geologic record. Past research found a significant increase in freshwater diatom abundances in marine sediments under the Northern California Current during late glacial time and inferred a Columbia River source. Site locations distal to the river mouth leave some uncertainty about the source. Here we analyze freshwater diatoms in sediment core OC1706B-06JC collected from the Oregon continental slope just off the mouth of the Columbia River. We find abrupt increases in the relative abundance of freshwater diatoms up to about half the total diatom assemblage during late glacial time. Our findings confirm a Columbia River source for flooding events. During an interval of laminated sedimentation, extreme variations of freshwater diatoms (e.g., from ~0 to 50% of the diatom flora) support the existence of many short-lived freshwater flux events rather than a few massive floods. Freshwater diatoms are also present in Holocene (post-glacial) sediments, reflecting site location under the modern river plume. Relatively subdued Holocene variability is significant, suggesting long-term variability in river flows to the ocean or productivity of freshwater diatoms within the drainage system. Our demonstration of a Columbia River source for freshwater diatoms in late-glacial marine records from the region, along with evidence for relatively subdued Holocene variability underpins efforts to understand the impact of large fresh-water fluxes on the ocean related to climate change.
Habitability at the frontlines of sea level rise: a spatiotemporal analysis of settlements and coastal inundation in Bangladesh between 1990 and 2015Sea level rise is the climate change impact with greatest potential to drive permanent human migration. As the case of Hurricane Katrina showed us, sudden, large-scale displacement is extremely disruptive to society both for migrants and host communities. We expect this problem to continue and accelerate into the 21st century and beyond. There is a serious science and policy need to understand how rising sea level will affect human population, and we can meet this need by examining where coastal inundation has already occurred. By using newly published global population grid (Global Human Settlement Layer) and global water occurrence (Global Surface Water) datasets we determined areas of historical settlement inundation and identified regions of high vulnerability or ‘hotspots’ using the case study example of Bangladesh. The methods outlined in this analysis led to a calculated historical settlement area loss of approximately 18 square kilometers since 1990 and the identification of 5 ‘hotspot’ regions of high vulnerability. As global datasets and analysis methods become more precise, geospatial analyses such as these will become increasingly important in modelling and predicting population vulnerability to natural hazards and crises.
Characterization of microbial communities experiencing differential methane flux in Arctic seafloor gas hydrate moundsMarine sediments are a source of methane, an important greenhouse gas if it enters the atmosphere in large quantities. Methanotrophy in seeps is important globally as it limits methane emissions to the hydrosphere by oxidizing large amounts of the hydrocarbon in sediments. Our goal is to determine how increased methane flux from sites of active seepage influences the sediment microbial community composition. (H1) We expect to see changes in microbial community composition between geochemical zones of distinct porewater chemistries below, within, and above the SMTZ and between gas hydrate mounds of differing methane flux patterns. (H2) We expect to see a correlation between known environmental parameters including sulfate, alkalinity, and sulfide with any community clustering patterns. (H3) We hypothesize that changes in community structure will be evident where sulfate diffusion models indicate longer exposure to a constant supply of saturated methane. Amplifiable DNA was extracted from 43 sediment samples recovered from seeps near Svalbard in the Arctic Ocean that differ in the degree to which the porewater chemistries are or are not at steady-state. Porewater sulfate determinations from the sites that are actively emitting methane exhibit concave-up profiles suggestive of increasing methane flux whereas one mound with no flare exhibits a profile suggestive of steady-state diffusive fluid kinetics. Sequencing and analysis of 16S DNA is underway in preparation for a comparison of microbial community composition from below, within, and above the sulfate methane transition zone to estimates of methane flux histories at the respective sites. These data will improve our understanding of the complex interplay between physical and biological processes occurring in these biogeochemically important sites.
Physical properties and extent of tsunami deposits within Alsea Bay attributed to the 1700 Cascadia earthquakeCascadia’s 1700 earthquake caused widespread subsidence of the Pacific Northwest coastline and a tsunami, which deposited sandy sediments in estuaries along on the Oregon coast such as Alsea Bay. While the recurrence of tsunami events in this area is recorded in the stratigraphy, the full extent of the inundated area is not understood. The ability to identify the reach of these tsunamis within the estuaries and bays is crucial to being able to protect people and infrastructure during future events. Gouge coring, outcrop analysis, study of the sediment composition and lithology, as well as recording of the tsunami generated deposits and their landward progression with GPS and LiDAR will be conducted at pre-selected sites. Analysis of the observed data via the tools and methods described and coupled with fluid dynamics and behavior models will aid in identification of areas at risk of inundation.
Marys Peak cloud images observation and estimates of cloud base, spacing, and velocityClouds play an important role in helping people understand weather and climate. This proposal presents the Marys Peak cloud camera, which views clouds, techniques employed to observe clouds in the Willamette Valley with the coast range as a backdrop. Through a series of photographs, the cloud-base height, horizontal spacing, and cloud base velocity will be determined using geo-referencing and images.