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These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The materials are free and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
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Instructor Materials: Overview of the Critical Zone Science Course

Course Goals: At the end of the course students will be able to:
  • Analyze technological advances, breakthroughs in interpretation, and new observations to build their understanding of the Critical Zone in and beyond the class.
  • Use a large variety of scientific principles to analyze how Earth's land surface works.
  • Apply data sets and observations from multiple existing CZO sites to test ideas and summarize Critical Zone services.
  • Describe the Critical Zone as a complex system of interacting regolith, water, air, and life.

Summative Assessment: There are two options for a summative assessment: (1) Students will progressively develop a faux NSF RFP justification for as new CZO observatory. They will report their findings in a 10 page (DS) paper and a 10-15 presentation at the end of the term. (2) Alternatively, instructors can ask students to describe and characterize how interaction among the atmosphere, lithosphere, hydrosphere, biosphere, and soil (The Critical Zone) support and influence life. A 10-15 minute presentation, and a 10-page, double-spaced, properly-referenced report of the a student identified, and instructor approved, topic that addresses one of the grand challenges in geosciences and the role the Critical Zone plays.

Course Description

Four general questions drive Critical Zone Science. Each question highlights how Critical Zone Science crosses scientific disciplines and both spatial and temporal time scales. (1) How do processes that nourish ecosystems change over human and geological time scales? (2) What processes control fluxes of carbon, particulates, and reactive gases over different time scales? (3) How do biogeochemical processes govern long-term sustainability of water and soil resources? (4) How do variations in and perturbations to chemical and physical weathering processes impact the Critical Zone? These four overarching questions frame the curriculum's learning objectives and each of the individual learning modules.

One overarching and four primary objectives provide the learning framework for this Critical Zone curriculum. Each module incorporates lessons and activities that target the objectives outlined below. Instructors will find these objectives reiterated at each of the module levels (e.g. Critical Zone Background) with references to specific examples of activities and/or readings within that unit which match the overarching and primary objectives.

Overarching objective:

Describe and characterize how interactions among the atmosphere, lithosphere, hydrosphere, biosphere, and soil (combined = The Critical Zone) support and influence life.

Four primary CZ Science objectives:

  1. Identify grand challenges that face humanity and societies, ways in which humans depend upon and alter the Critical Zone, and the potential role for Critical Zone science to offer solutions for these challenges.
  2. Use and interpret multiple lines of data to explain Critical Zone processes.
  3. Evaluate how the structure of the Critical Zone influences Critical Zone processes/services.
  4. Analyze how water, carbon, nutrients and energy flow through the Critical Zone and drive Critical Zone processes.

Course Outline

Modules 1 and 2 serve as introductory modules. Modules 3-7 are interdisciplinary science modules.

Module 1 CZ Background (Four 75 minute class sessions total)

Students are introduced to the Critical Zone as a complex system. Much of Critical Zone science is applied to conceptualizing and constructing systems models that allow scientists to predict the effects of ongoing land-use and climate change.
  • Unit 1.1: CZ Overview (One 75 min class session)
    • This lesson is an introduction to Critical Zone science from which students should grasp key concepts: 1) Critical Zone science is multi- and interdisciplinary; 2) Critical Zone processes are represented by coupled physical, biological, and chemical processes; and, 3) an array of scientific expertise in many fields including geology, soil science, biology, ecology, geochemistry, geomorphology, hydrology, and more, is needed to understand the Critical Zone.
  • Unit 1.2: Role of Soils (Two 75 min class sessions)
    • The focus in this lesson is on issues relating to the state factors of soil formation, methods of soil description and classification in the field, soil orders, soil surveys, and threats to soil including soil erosion.
  • Unit 1.3: Systems Models (One 75 min class session)
    • Students will consider basic concepts of system science specifically applied to Critical Zone science. Students will develop a qualitative systems model graphic of the Critical Zone. The knowledge gained here will be applied later in the semester.

Module 2Methods of Critical Zone Science (Four 75 minute class sessions total)

Students are introduced to different types of data and the techniques for interpreting data and information.
  • Unit 2.1: Basic Tools & Analysis (Two 75 min class sessions)
    • Invite a librarian to class and review library research methods. Students will produce an annotated bibliography and demonstrate a basic ability to analyze data using Excel.
  • Unit 2.2: Basic Critical Zone Concepts (Two 75 min class sessions)
    • Class breaks up into teams that present short summaries of basic Critical Zone concepts, drawn from many sources.

Module 3 Critical Zone Architecture and Evolution (Four 75 minute class sessions total)

Students are introduced to how diverse geological processes interact to form diverse landscapes. Commonalities exist within this diversity, marked by similar landforms which often indicate similar processes of formation that in turn may control some CZ processes.
  • Unit 3.1: Geology and Geomorphology (Two 75 min class sessions)
    • Some basic concepts of geology will be considered in this lesson especially focused on how rocks and sediments affect soil formation and many related Critical Zone processes.
  • Unit 3.2: Landforms and Remote Sensing (Two 75 min class sessions)
    • Geomorphic environments and the processes that can move and shape them are explored in this lesson to learn about the links between landforms, soils, and the Critical Zone.

Module 4Land-atmosphere exchange (Four 75 minute class sessions total)

Energy and carbon fluxes and budgets provide both the energy and raw materials for many of the processes taking place in the Critical Zone, particularly photosynthesis. This module will explore both the energy and carbon budget using data from CZO and other field sites.
  • Unit 4.1: Energy Budgets (Two 75 min class sessions)
    • Students will use CZO datasets to describe the differences between the main atmospheric fluxes at each CZO site. They will use these data to trace the primary radiative forcings through the critical zone at each CZO site.
  • Unit 4.2: Carbon Budgets (Two 75 min class sessions)
    • Students will analyze carbon flux data collected at various scales to understand the regional exchange of carbon at a CZO site. They will apply projections of future climate conditions to assess the impact of those conditions on CZO processes.

Module 5Water transfer through the CZ (Four 75 min class sessions total)

This module builds on the previous one but focuses on Critical Zone water transfers at multiple scales. This module encourages systems thinking, with the ultimate focus on two points: first, that in a mass balance, inputs must equal outputs plus the change in storage, and second that a tree can be an important part of the water balance.
  • Unit 5.1: Water Balance of a Tree (Two 75 min class sessions)
    • Students will calculate a mass balance for an individual tree before scaling up to the catchment level. Multiple approaches are used, including an equation-based problem set, and a graphical simulation exercise.
  • Unit 5.2: Links between Land Cover and Stream Discharge (Two 75 min class sessions)
    • Students will think about various feedbacks and assumptions that might affect scaling a tree water balance up to the size of a catchment. They will also try their hand at allocating water among competing users at the watershed scale.

Module 6 Geochemistry and Biogeochemistry (Five 75 minute class sessions total)

This module examines the integrated roles that geology, biology, and chemistry play in CZ. By engaging students in examining data from real world systems, this module highlights the biogeochemical functions the CZ plays and the functions the CZ play. Through the subunits of phosphorus and eutrophication and weathering and transport, students will come to realize why the key to understanding critical zones lie in the biogeochemical characteristics.
  • Unit 6.1: Biogeochemical cycling - Modeling: Nutrient inputs and transformation (Three 75 min class sessions)
    • Using the scientific literature students will study how nutrients move among and within ecosystems at different scales and across space and time. The role of organisms and the utility of ecological theory in biogeochemical processes will be explored. Biogeochemical processes will be applied to humanity's grand challenges includes climate change and environmental stability.
  • Unit 6.2: Biogeochemical cycling - Example: phosphorus and eutrophication (Two 75 min class sessions)
    • Students will explore the impact CZ have on clean water through use of CZO data and will explain the differences in land use on nutrient cycling and CZ functions.

Module 7 Humans in the Critical Zone (Four 75 minute class sessions total)

All humans live in the Critical Zone and depend on it for resources necessary for their livelihoods. However, while conducting daily activities, humans affect the natural Critical Zone processes upon which they depend. This two-way interaction is explored through readings, computer simulations, and discussions.
  • Unit 7.1: Model My Watershed (Two 75 min class sessions)
    • This unit focuses on the land/water connection and on how human-induced land use change affects local hydrology. Students will predict the amount and destination of water as it moves through built environment by focusing on the effects of land-cover type, soil texture, and slope using a watershed simulation package called "Model my Watershed."
  • Unit 7.2: Agricultural Impacts (One 75 min class session)
    • This unit focuses on the impact humans have on soil and water resources by focusing on a series of readings and related discussions related to the Dust Bowl of the 1930s and more recently on programs such as Community Supported Agriculture.
  • Unit 7.3: Panel Review (One 75 min class session)
    • Peer review is an important process in determining priorities for scientific research. Students will engage in a panel review of new CZO proposals and as a class decide on the proposal most worthy of funding. Students will read proposals and discuss the merits and limitations of each during an in-class panel review.

Adapting the Course to Different Structures, Formats, and Schedules

This course is easily adaptable to different structures, formats, and schedules. The total amount of resources made available for this Introductory to the Critical Zone course is more than needed for one semester-long course. However, this is an intentional design. Our aim as authors is to provide sufficient resources so that the instructor has flexibility in tailoring and fine-tuning the course to their expertise and the level and interest of the students. Therefore, no instructor should aim to use and complete all of the resources and activities made available. The diversity of resources ensures that by opting to omit certain resources and activities, that the overall structure and integrity of the curriculum will remain and students will have a complete introduction to Critical Zone science. For more information, we encourage you to explore:

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These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »