Frank M. Dunnivant

A Comprehensive Stream Study Designed for an Undergraduate Non-Majors Course in Earth Science

Science courses for students not majoring in science present unique teaching challenges to educators. Often non-science majors need help seeing the relevance of the course material and making connections between science and their own lives. One promising way to motivate these students and increase their level of interest and understanding is to teach in an integrated lab/lecture format using inquiry-based methods. Such activities maintain a constant level of attention from the students by requiring them to collect their own data, analyze the data set, interpret their data, and prepare a class presentation of their findings. We are experimenting with a new set of science courses that are designed to be interdepartmentally staffed, to integrate aspects of mathematics, geology, chemistry, and biology in am environmental theme, and to use guided-inquiry methods in a lab/lecture format. The interdisciplinary faculty team provides students with a diverse set of backgrounds and skills, and the interaction betwee...

Fraction of organic carbon predicts labile desorption rates of chlorinated organic pollutants in laboratory‐spiked geosorbents

The resuspension of large volumes of sediments that are contaminated with chlorinated pollutants continues to threaten environmental quality and human health. Whereas kinetic models are more accurate for estimating the environmental impact of these events, their widespread use is substantially hampered by the need for costly, time-consuming, site-specific kinetics experiments. The present study investigated the development of a predictive model for desorption rates from easily measurable sorbent and pollutant properties by examining the relationship between the fraction of organic carbon (fOC) and labile release rates. Duplicate desorption measurements were performed on 46 unique combinations of pollutants and sorbents with fOC values ranging from 0.001 to 0.150. Labile desorption rate constants indicate that release rates predominantly depend upon the fOC in the geosorbent. Previous theoretical models, such as the macro-mesopore and organic matter (MOM) diffusion model, have predicted such a relationship but could not accurately predict the experimental rate constants collected in the present study. An empirical model was successfully developed to correlate the labile desorption rate constant (krap) to the fraction of organic material where log(krap)=0.291-0.785 . log(fOC). These results provide the first experimental evidence that kinetic pollution releases during resuspension events are governed by the fOC content in natural geosorbents.

A Simple Sand Column Laboratory Exercise to Illustrate Pollutant Hydrology in Groundwater Systems

The transport of pollutants in groundwater systems is an important concept taught in contaminant hydrology. Yet, surprisingly, no relevant soil column experiments have been described in the pedagogical literature (Journal of Chemical Education, Chemical Education Research and Practice, or Journal of Geoscience Education). This experiment illustrates the transport of tracers in a sand column using the conservative (non-retained and non-reactive) tracer fluorescein, along with a step input of non-conservative (retained/adsorbed) cadmium ion. The experiment is easy to set up, uses inexpensive commercially-available glassware and sand, and is highly reproducible. Step inputs of conservative tracer elute in one pore volume (the volume needed to completely replace the water held in the saturated column), with cadmium eluting in three pore volumes. This experiment can be completed in two, three-hour laboratory periods.

TEACHING POLLUTANT FATE AND TRANSPORT CONCEPTS TO UNDERGRADUATE NON-SCIENCE MAJORS, ENVIRONMENTAL SCIENTISTS, AND HYDROLOGISTS USING ENVIROLAND

Our team has developed a user-friendly software package, EnviroLand©, for teaching hydrological fate and transport concepts to undergraduate students. We have successfully used this program in introductory Earth science courses, environmental chemistry, geochemistry, and geohydrology. EnviroLand contains basic transport models for river, lake, and groundwater systems and can be used to simulate the transport of pollutants under a variety of conditions. A free copy of EnviroLand can be downloaded from http://www.edusolns.com/.

High-density element concentrations in fish from subtidal to hadal zones of the Pacific Ocean

Anthropogenic use of high density, toxic elements results in marine pollution which is bio-accumulating throughout marine food webs. While there have been several studies in various locations analyzing such elements in fish, few have investigated patterns in these elements and their isotopes in terms of ocean depth, and none have studied the greatest depth zones. We used a flame atomic absorption spectrophotometer-hydride system and an inductively coupled plasma-mass spectrometer to determine concentrations of the high-density elements arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), plus the light-metal barium (Ba), in fish ranging from bathyal (1000 m in Monterey Bay) to upper hadal zones (6500–7626 m in the Kermadec and Mariana Trenches) in the Pacific Ocean. Five species of fish—including the Mariana Trench snailfish, the worlds deepest known fish newly discovered—were analyzed for patterns in total element concentration, depth of occurrence, Se:Hg ratio, plus mercury isotopes in the deepest species. Co and As levels decreased with depth. In the Mariana Trench, Pb, Hg, Cd, and Cu were higher than in all other samples, and higher in those plus Ba than in the Kermadec Trench. The latter samples had far higher Ni and Cr levels than all others. Mercury relative isotope analysis showed no depth trends in the deepest species. Se:Hg showed a large molar excess of Se in bathyal flatfish species. These patterns indicate that exposures to pollutants differ greatly between habitats including trenches of similar depths.

TEACHING CHEMICAL SPECIATION TO ENVIRONMENTAL CHEMISTS AND GEOCHEMISTS USING ENVIROLAND

A new software package, EnviroLand©, is available for teaching chemical speciation of acids and bases in environmental chemistry and geochemistry. The program is appropriate for undergraduate and graduate instruction. EnviroLand has been used in a variety of ways including as an inquiry-based exercise, as a lecture aid, a system for checking spreadsheet logic and calculations, and a key to homework assignments. Computer-assisted instruction is rapidly becoming a common tool in the classroom, but software packages should be designed to be interactive so that student learning will be enhanced.

EnviroLand: A Simple Computer Program for Quantitative Stream Assessment

that developed countries have made is the treatment of sewage waste and the subsequent protection of natural water bodies from eutrofication. Healthy water bodies typically contain low organic matter levels and the absence of organic matter allows the presence of high dissolved oxygen levels (referred to as D.O.). However, even under optimum conditions (7° C) water can only contain approximately 12 mg/L (parts per million) as opposed to the 190,000 parts per million (19%) that we utilize from the atmosphere. When organic waste is released into streams and lakes, microorganisms in the water use the relatively small amount of D.O. to digest the waste. For this reason, we refer to the waste as exerting a BOD on the system. BOD is the Biochemical Oxygen Demand and it is the amount of dissolved oxygen (in mg/L) that microbes need to completely oxidize the organic waste. It is important to note the distinction between D.O. and BOD. The D.O. is a chemical measurement of the dissolved oxygen content in the stream, while BOD is a reflection of the D.O. consumed in oxidizing the waste. Typical domestic sewage contains between 100 and 200 mg/L BOD. Thus, when this waste is released into the water body, the microorganisms need between 100 to 200 mg oxygen/L to oxidize (consume) the waste. If this oxygen is not present or cannot be supplied from the atmosphere, the aquatic system will become anaerobic (devoid of oxygen) and pose problems for aerobic life forms (i.e., fish, macroinvertebrates, etc).