Biogeochemical Processes and Cycles

Karen McNeal,
Geosciences, Mississippi State University

Summary

An investigation into the various biogeochemical cycles (C,N,P,S, and metals), the microorganisms and the chemical reactions that take place during theses cycles, the environments in which theses processes occur (e.g., hydrosphere, lithosphere, and atmosphere - specifically wetlands, oceans, estuaries, soils, and sediments), and the various methodologies used to measure these processes. These Earth systems and processes are innately complex in nature, this course aims to support students' understanding of these systems through lecture, literature, and group assignments.

Course Size:

fewer than 15

Course Format:

Lecture only

Institution Type:

University with graduate programs, including doctoral programs

Course Context:

This is a graduate level course with pre-requisites of introductory chemistry. The majority of the students are geologists in the geoscience department. The students enrolled typically take the course to satisfy the 8000 level graduate course requirements. The course requires some time outside of the lecture portion to complete group work and laboratory assignments.

Course Content:

This course is intended as an introductory course to biogeochemistry. The goals of the course include (1) learning the basic chemical cycles that occur in the various Earth systems and the environments in which these reactions occur; (2) examining the types of organisms involved in these processes (3) understanding the basic geochemical concepts including redox chemistry, thermodynamics, kinetics, and acid-base chemistry (4) identifying the typical procedures and methods used to measure these processes on the Earth, and (5) examining the literature concerning biogeochemistry.

Course Goals:

The learner will identify the chemical cycles that take place on the Earth; the learner will explain how microoganisms are involved in these processes; the learner will be able to explain the various geochemical reactions that are important in biogeochemical cycles; the learner will be able to identify the environments in which these cycles occur, how they differ, and what instrumental, laboratory, and field methods are used to measure these processes; the learner will also be able to identify key journals, literature, and authors that are presently researching the various core areas within biogeochemistry.

Course Features:

This course employs a combination of lecture based teaching, with individual student presentations and homework assignments, and group assignments and discussions. During the "lecture" days traditional lectures are combined with jigsaw activities to help students review basic chemistry concepts and review of various biogeochemical methods. Students also work in teams to design their own Winogradsky column experiment through inquiry-based learning approaches. Student teams complete the laboratory work and final report that summarizes their Winogradsky and soil respiration experiments. During paper presentations, students choose biogeochemical related research papers and present the paper to the rest of the class. Presenting and non-presenting students are required to submit short paper summaries and participate in class discussions as part of their presentation grade. Mid-term and final exams are employed as summative assessments.

Course Philosophy:

This teaching style was chosen because I believe it provides students the scaffolding necessary to learn the complex nature of the processes and systems that are discussed in the course while simultaneously allowing them to explore these phenomenon on their own through group and inquiry based learning approaches. Furthermore, students are challenged to critically think about biogeochemcial research through reading scientific papers and presenting to their peers which better prepares them for their own scientific careers.

Assessment:

A mid-term, a final exam, two group reports, a homework problem set, and individual student presentations are employed as summative assessments. Group presentations, in-class jigsaws, class discussions, and the journal review form are used as formative assessments.