CWR6252 Environmental Biogeochemistry of Trace Metals

1. CWR6252EnvironmentalBiogeochemistryof Trace Metals Dr. Lena Q. MaProfessorSoil and Water Sciences Tel: 352-392-9063 ext. 208 Dr. Jean-Claude J. Bonzongo Associate Professor Environmental Engineering Tel: 352-392-7604

2. 1. SYLLABUS • 1.1. Course description and objectives • This course focuses on fate and impacts of trace metals/metalloids as they cycle through geological and biological environmental compartments. • The course provides students with a scientific basis to biogeochemical approaches and a foundation upon which they can develop the ability to analyze, predict, and solve environmental problems related to metal pollution. • 1.2. Pre-requisites: • Include at least one of the following: general chemistry, inorganic/organic chemistry, biochemistry, environmental chemistry, soil and water chemistry or permission of the instructors • 1.3. Textbook:None

3. 1.4. Course Format • The course consists of lectures, student presentations, and chats using Mbreeze. • Location: McCarty Hall D G-001M, W & F 4th period (10:40 to 11:30 am) for on-campus (OC) students • Delivery via internet for distant education (DE) students. For DE students, presentations will be delivered via Mbreeze. • 1.5. Course Web Site • Chat web site via Mbreeze: http://mbreeze.ifas.ufl.edu/cwr6252: enter as a guest and type your first name. Everyone is required to attend chat sessions, starting the second week. • 1.6. Class web site: • http://lqma.ifas.ufl.edu/cwr6252/cwr6252.html.

4. 1.7. Assessment Methods: Grades will be determined based on performance on homework, term papers, and oral presentations.The weight of the above assignments towards the final grade will be calculated as follows: 60% for homework, 30% for term papers, and 10% for oral presentations 1.8. Grade Scale A 95 – 100 A- 90 – 94 B+ 85 – 89 B 80 – 84 B- 75 – 79 ______________________________ C+ 70 - 74 C 65 – 69 C- 60 - 64

5. 1.9. Course Structure INTRODUCTION GEOCHEMICAL BACKGROUND METALS IN THE HYDROPSHERE METALS IN SOILS AND PLANTS CASE STUDIES BIOGEOCHEMISTRY OF SELECTED TRACE METALS

6. LECTURE 1

7. Concepts in Environmental Science Understanding of natural orders Identification of anomalous deviations from natural orders Solving environmental problems Accumulate knowledge that support proactive approaches to avoid or limit future environmental and health problems

8. Example of Natural Order: The Periodic Table

9. IMPORTANCE OF TRACEELEMENTS AND ENVIRONMENTAL IMPLICATIONS EARTH ATMOSPHERE • Nitrogen 78.0842% • Oxygen 20.9463% • Argon 0.9342% • Carbon dioxide 0.0381% • Water vapor ~1.0000% • Other 0.0020%

10. WHY FOCUS ONLY ON TRACE METALS? Occurrence at very low ( trace) levels Sensitivity to anthropogenic activities Toxic at relatively low levels and impacts on living organisms and human health

11. THE BEGINNING BIG BANG: widely accepted model based on a giant explosion some 10 to 15 BYA ORIGIN OF THE EARTH SYSTEM AND ELEMENTAL ABUNDANCE

12. THE ORIGIN OF THE ELEMENTS Log [abundance] Si = 6 Atomic Number

13. NUCLEAR CHEMISTRY CONTROLS THE NATURAL ABUNDANCE OF CHEMICAL ELEMENTS

14. Cosmic Abundances of the Elements (cont’d) 1 2 3 4

15. Cosmic Abundances and Origin of the Elements 1 H-Fusion Synthesis by H-fusion stopped at Li b/c formation of next elements such as carbon required higher density particles and different T-range. Big bang produced H and He served as “feed stock” from which all heavier elements were later created

16. Cosmic Abundances and Origin of the Elements 2 Alpha addition  Triple a sequence: 4He+4He8Be+4He12C Subsequent additions produce elements up to Fe Reactions are highly exothermic = energy source These nuclear bombardments are reactions that produce free neutrons (n) as illustrated below 13C(a,n)16O and 22Ne(a,n)25Mg

17. Cosmic Abundances and Origin of the Elements Low flow of neutron S-process Neutrons produced during a-addition reactions interact with nuclei of any mass at existing temperature to produce chemical elements up to Bi, which is the heaviest stable element in the periodic table. (Mechanism on next slide)

18. b-decay stops the buildup of neutron and limits the formation of new elements to bismuth (Bi). At this point, the r-process is necessary for formation of much heavier elements

19. Cosmic Abundances of the Elements • Occurs in explosive environments such as supernovae, and where the neutron flux is very high and the interaction time between neutrons and nuclei is very short • Similar to the s-process, but is more rapid • No time for isotopes to undergo b-decay • Produces highly unstable (radioactive) elements r-process

20. ENVIRONMENTAL IMPLICATIONS OF ELEMENT NATURAL ABUNDANCES • Trace metals are rare and usually extracted from crude ores • Mining and processing release trace metals to different environmental compartments • Exposure to high levels of trace metals • Toxicity on human health and impacts on ecological functions