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School of Environment, Education and Development

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BSc Geography and Geology
Benefit from a wide range of optional topics and practical trips on this combined degree.

BSc Geography and Geology / Course details

Year of entry: 2018

Course unit details:
Global Biogeochemical Cycles

Unit code EART20092
Credit rating 10
Unit level Level 2
Teaching period(s) Semester 2
Offered by School of Earth and Environmental Sciences
Available as a free choice unit? Yes


This course introduces the rationale for considering the fluxes and interactions of the main elements and nutrients in the Earth system. It includes the necessary descriptions of its major compartments: the atmosphere; the biosphere; the ocean and the lithosphere; and introduces key concepts of reservoirs, fluxes, residence times and lifetimes. The main cycles are considered, including the carbon cycle, the water cycle, the oxygen, sulphur, nitrogen and phosphorous cycles and their couplings are discussed. Other important cycles, such as those of iron and the halogens may also be introduced.  Human impacts on the key natural cycles will be discussed in the context of global and regional environmental change.


To provide an overview of the cycling of key nutrients through the Earth System focussing on carbon, nitrogen, sulphur and phosphorous

 To introduce the key aspects of the main reservoirs in the Earth System and their interaction

 To develop quantitative approaches to assessing budgets and fluxes in global natural cycles.

Learning outcomes

On successful completion of the course students will understand:

•       The carbon, nitrogen, sulphur and phosphorous cycles in the Earth System

•       How the key reservoirs in the Earth System: the atmosphere; the oceans; the biosphere and the lithosphere interact with and control the key cycles

•       Key nutrient cycles through the Earth System, their main reservoirs and fluxes

•       The main human impact on the C, N, S and P cycles and the implications of these perturbations

And will have:

•           Developed numerical and intellectual skills through problem-based exercises




Week 1: Introduction

Introduces the rationale for considering the fluxes and interactions of the main elements and nutrients in the Earth system.  Introduces the reservoir model and concepts such as fluxes and lifetimes.


Week 2: Atmosphere and Ocean

Introduces the key features and processes of the atmosphere and ocean compartments including circulations and how these control the flow of heat and chemicals around the planet.


Week 3: Lithosphere and Carbon Cycle

Overview of the lithosphere, how this has changed over earth’s history and its role in interacting with other compartments. Introduction to the carbon cycle covering major forms and processes.


Week 4: Carbon Cycle Budgeting and Feedbacks

Budgeting for carbon within the major compartments of the earth system and processes that result from responses to other changes such as temperature.


Week 5: Computer based exercise and assessment 1

Computer-based exercise developing a model of the global carbon cycle


Week 6: Nitrogen Cycle

Forms and processes governing the nitrogen cycle including the processes of fixation and fertilisation. Human perturbations on the nitrogen cycle and how these affect the environment.


Week 7: Sulphur Cycle

Forms and processes governing sulphur cycle, including natural and human emissions to the atmosphere and how these influence weather and climate.


Week 8: Phosphorous Cycle & Discussion

How phosphate is cycled, how this is influenced by human activity and what influences this has on local ecosystems. This is followed by a discussion session concerning how biogeochemical cycles influence climate change.


Week 9: Mathematical problems

Exercises based on calculations, focusing on budgeting of reservoirs, fluxes and lifetimes.


Week 10: The Water Cycle

The main processes governing the water cycle including how this interacts with the other biogeochemical cycles and how this is being perturbed by human activity.


Week 11: Revision lecture

Assessment methods

Method Weight
Other 20%
Written exam 60%
Set exercise 20%

Assessment methods


Computing assignment report


Written exam


Open book test


Assessment:Formative assessment

In course problems will be provided.

FEEDBACK an overview of the answer provided in subsequent lectures
A revision class involving past exam questions will be provided FEEDBACK in class

Assessed coursework

            Assessment on feedbacks in the global system based on the computing assignment (20% of the total 10 credits) FEEDBACK will be individual and also an example answer submitted by Blackboard.
            An open book question similar to that set in the examination will be set towards the end of the course worth 20% of the final mark. FEEDBACK: a set answer and individual feedback will be provided over Blackboard


            A 1.5 hour examination worth 60% of the final mark will be set. There are 2 sections on the paper, each containing 2 questions, you must answer one question from each section. A total of 50 marks are available in the examination, 20 marks for the part A question and 30 marks for the part B question. Part A questions are calculation based questions and part B questions are essay based.



Feedback methods

In course problems will be provided.

FEEDBACK an overview of the answer provided in subsequent lectures
A revision class involving past exam questions will be provided FEEDBACK in class


Recommended reading

W. H. Schlesinger (1997) Biogeochemistry: an analysis of global change. Academic Press, (ISBN 012625155X).

M. C. Jacobson, R. J. Charlson, H Rodhe and G. H. Orians (2000) Earth system Science From biogeochemical cycles to Global Change, Elsevier (ISBN 0-12-379370-X)

Climate Change 2013: The Physical Science Basis

Study hours

Scheduled activity hours
Lectures 15
Practical classes & workshops 5
Tutorials 2
Independent study hours
Independent study 78

Teaching staff

Staff member Role
James Allan Unit coordinator

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