Determination of Bioaccumulated Trace Metals in Marine Macroalgae

College of Natural Resources & Sciences

Trace metal bioaccumulation negatively impacts marine ecosystem health and increases the risk of human exposure to contaminants. Pollution trends can be investigated by measuring trace metal bioaccumulation in algae, but little is known about which algal groups are the most reliable bioindicators. The objectives of this study were to use dry ashing, wet digestive, and spectroscopic techniques to determine the concentrations Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn across major macroalgae groups in Humboldt Bay, and evaluate bioindicator ability using BSAF values. Our results indicate that Chlorophyta and Rhodophyta are the most sensitive and suitable bioindicators for trace metal pollution.

Determination of Metal Accumulation and Loading in the Oxidation Ponds at the Arcata Wastewater Treatment Facility

College of Natural Resources & Sciences

The determination of temporal variations of metals, in the primary effluent and oxidation ponds, were collected biweekly (2007-2008) and weekly (2012-2013) at the Arcata Wastewater Treatment Facility. The data demonstrates the removal of contaminant metals in the oxidation ponds through sludge deposition as well as the role weather events play in elevated metal concentrations. The sludge in the oxidation pond systems where also measured to allow the projection of the accumulation of metals in the sludge within the system 30 years from now.

Determining Habitat Prferences of Great Egrets through Foraging Rates

College of Natural Resources & Sciences

My research project looked into determining habitat preferences of Great Egrets through foraging rates across Arcata, CA. The three habitats I chose were the Arcata Marsh, Mad River Slough, and Agricultural Fields.

Determining Iron Concentrations in Seawater using Flow Injection Analysis

College of Natural Resources & Sciences

Iron concentrations in the ocean are important for the health and success of the ocean because it is an essential micronutrient for phytoplankton. However, iron is insoluble in oxygenated seawater and so most iron precipitates and sinks out of the water column. Here we present a method to analyze these low concentrations of iron using flow injection analysis, which we built following Lohan et al. (2006).

Determining Magma Mixing Duration and Dynamics Through Analysis of Reaction Rims on Olivine Crystals in Natural Samples of Black Dacite From the 1915 Eruption of Lassen Peak, CA

College of Natural Resources & Sciences

Disequilibrium reaction rim textures on olivine grains from black dacite from the 1915 eruption of Lassen Peak were measured and coupled with experimental reaction rim growth rates to estimate the duration of magma mixing that took place prior to the 1915 eruption. Reaction rims on 100 olivine grains were measured and the duration of magma mixing prior to the 1915 eruption was estimated to be between 12-17 months. The abundance of reaction rim growth varies during the duration of magma mixing and is evidence that the eruption of Lassen Peak was catalyzed by multiple injections of hot basaltic andesite into a relatively cool and mushy dacitic reservoir magma chamber prior to eruption.

Developing a three-dimensional culture system to improve the yield of placental mesenchymal stem cell derived extracellular vesicles

College of Natural Resources & Sciences

In this study, we developed a novel approach to produce placental mesenchymal stem cell derived extracellular vesicles (PMSC-EVs) by utilizing a three-dimensional (3D) cell culture system to potentially use in regenerative medicine applications. CELLine bioreactors are a 3D culture system that is comprised of a polystyrene scaffold, to support a high-density culture, encased in a semipermeable membrane to concentrate all proteins produced by the cells within. When conditioned medium is collected from the compartment PMSC-EVs were produced over an eight-week continuous culture. This method potentially could be used as an alternative to conventional culture methods to improve PMSC-EV yield.

Development and Stable Integration of Tetracycline Inducible Tools for Genome Editing and Genome Regulation in Cultured Human Embryonic Kidney Cells

College of Natural Resources & Sciences

At Humboldt State University we aim to create a robust CRISPR/Cas9 toolkit which enables one to overexpress, repress, inhibit transcription and perform double strand DNA cuts allowing one to undertake research on genes associated with cancer, autophagy and neurological diseases. These tools will enable future students, private sector, and academia to investigate a wide range of biological questions. Currently in the CRISPR/Cas9 system there are inherent problems ranging from indel mutations, poor gene locus targeting, low efficiency, and in vivo applications.We built upon the knowledge in Dr. Steele’s lab and chose to perform Hi-Fi assembly to overcome technological limitations that lowered.

Dissolved Trace Metal Depletion Anomalies and Hydrothermal Interaction in South Pacific Deep Water

College of Natural Resources & Sciences

The array of metals obtained from the GEOTRACES cruise in 2013 provides evidence for anomalous metal behavior. Trace metals in the ocean can act as indicators of hydrothermal vents, providing evidence for iron and magnesium sources to the ocean. However, anomalies of other dissolved trace metals (DTM) have been observed at theoretical hydrothermal vent sites, specifically depletions of cerium, lanthanum, nickel, and yttrium. Initially, these depletions were thought to be the result of redox reactions, but this only partially explained the DTM deficiencies. Particulate scavenging through the formation of metal oxides from DTM is also a possible cause for anomalous depletion.

Distribution of Microplastics at the Surface and Within the Water Column in Humboldt Bay, Northern California

College of Natural Resources & Sciences

This study focused on microplastic concentrations in and around Humboldt Bay, CA. Microplastics do not have a universal size class, but for the purpose of this study, microplastics were categorized as any plastic piece from 0.335 mm to 4.75 mm. Samples were taken on Humboldt State's research vessel "Coral Sea", and by foot on surrounding mudflats. Both water and sediment samples were collected and analyzed to find the amount of microplastic particles per mass sampled. Visual microscopy was utilized to create counts for each station.

Distribution of Western Thatching Ant Mounds and Their Effects on Soil Conditions in a Coastal Dune Ecosystem

College of Natural Resources & Sciences

Western thatching ant (Formica obscuripes) mounds are a conspicuous feature in the coastal beach pine forests of the local Lanphere and Ma-le’l Dunes. We explored the mounds’ size and spatial distributions, and tested whether their mound-forming behaviors could impact soil nutrient conditions. In a 3-km segment, we found 346 mounds generally situated along the sand–forest interface. Furthermore, from soil samples of seven of the mounds, we found that the ants significantly concentrated the soils with nutrients necessary for plant growth. These findings suggest that the ants could have important implications for supporting plant populations in this nutrient-poor environment.