Dr. Pamela P Benz

Petroleum products in the environment can produce significant toxicity through photochemically driven processes. Burning surface oil and photochemical degradation were two mechanisms for oil removal after the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico. After burning, residual oil remains in the environment and may undergo further weathering, a poorly understood fate. Although photochemistry was a major degradation pathway of the DWH oil, its effect on burned oil residue in the environment is under studied. Here, we ignited Macondo surrogate crude oil and allowed it to burn to exhaustion. Water-accommodated fractions (WAFs) of the burn residue were created in full sunlight to determine the effects of photochemical weathering on the burned oil residue. Our findings show that increased dissolved organic carbon concentrations (DOC) for the light unburned and light burned after sunlight exposure positively correlated to decreased microbial growth and production inhibition (i.e. more toxic) when compared to the dark controls. Optical and molecular analytical techniques were used to identify the classes of compounds contributing to the toxicity in the dark and light burned and dark and light unburned WAFs. After light exposure, the optical composition between the light unburned and light burned differed significantly (p < 0.05), revealing key fluorescence signatures commonly identified as crude oil degradation products. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis showed more condensed aromatic, reduced oxygenated compounds present in the light burned than in the light unburned. FT-ICR MS also showed an increase in the percent relative abundance of carboxyl-rich alicyclic molecules (CRAM) like compounds in the light burned compared to light unburned. The increase in CRAM suggests that the composition of the light burned is more photorefractory, i.e., reduced, explaining the residual toxicity observed in microbial activity. Overall, these data indicate burning removes some but not all toxic compounds, leaving behind compounds which retain considerable toxicity. This study shows that burn oil residues are photolabile breaking down further into complex reduced compounds.

Petroleum products are introduced into the environment through a variety of mechanisms and are shown to produce highly reactive oxygen species though photochemical reactions. For example, potential contamination can occur from motor oil leaked or spilled by recreational water vehicles such as boats and jet skis. Motor oils, both synthetic and non-synthetic, can produce potentially toxic components through natural weathering processes. Chemicals produced through photochemical processes are examined to help assess overall ecosystem impact and better understand mechanisms of toxicity. This study examined photochemical degradation and subsequent toxicity of both crude oil and water collected from local marinas. Using a high performance liquid chromatography (HPLC) method for detection of hydroxyl radical (·OH ), benzoic acid was added to each sample prior to irradiation. Benzoic acid served as a radical trap for OH produced. The resulting formation of para-hydroxybenzoic acid (p-HBA) was measured and total ·OH formation determined.

Undergraduate science, technology, engineering, and mathematics (STEM) experiences have academic, psychological, and social challenges that require additional support to navigate. This article explains the implementation of a STEM peer coaching program designed to provide such support. Through this program, undergraduate STEM students served as STEM peer coaches. Coaches facilitated one-on-one conversations focused on individualized support and skill development. Using carefully constructed planning and reflecting conversations, STEM peer coaches helped students clarify their goals and create plans for success. STEM peer coaches also served as accountability partners. Anecdotal evidence from students who participated in the program shows that STEM peer coaches provided meaningful academic support. The STEM peer coaching program is a model for how peer-led, individualized conversations can be a catalyst for helping students through challenges related to STEM. The article discusses key strategies for developing and implementing a STEM peer coaching program.

Engagement in active learning and learning communities is important for persistence of STEM students early in their academic programs. Colleges and universities have an ongoing call to facilitate active learning techniques, yet large group, lecture-based instruction is still the prominent method of instruction. This qualitative case study examines interviews and classroom observations of undergraduate chemistry students enrolled at a primarily undergraduate institution. Critical educational elements were identified for chemistry students participating in a redesigned, introductory course which included a collaborative peer-lead learning experience. The participants engaged in required, weekly sessions structured around community building and active learning. The data were framed through a community of practice (CoP) framework, and emergent themes were centered on the following components: mutual engagement, joint enterprise, and shared repertoire. Findings show participant engagement created opportunities for collaboration beyond the required, weekly sessions, which included forming study groups and seeking assistance from chemistry tutors. Participants also shared study techniques based on a mutual understanding that effective learning required routine practice. Implications for STEM departments and researchers about implementing research-based curriculum are discussed.

This qualitative case study presents interview responses, classroom observations, and survey responses of college students in an introductory chemistry course. The participants engaged in required, weekly sessions that were focused on facilitating active learning. The data were framed through a community of practice theoretical framework and emergent themes were centered on the following components: mutual engagement, joint enterprise, and shared repertoire. Participants’ engagement led to collaborations beyond the required, weekly sessions that included forming study groups and seeing chemistry tutors. They also shared study techniques that were based on the mutual understanding that chemistry learning required routine practice. Implications for college leaders and researchers about implementing research-based pedagogies are discussed.