In this lesson students will understand basic water quality issues focusing on heavy metal pollution. Through a series of background activities and case studies, students will explore what it means for water to be polluted and what the human health impacts are. Students will observe metal toxicity by completing a 50% lethal dose lab (LD-50 lab), and remediating the contaminated solutions using phytoremediation. They will repeat the LD-50 lab to observe differences in the remediated solution. This activity is designed to increase students’ awareness of water quality issues related to heavy metal contamination, and to explore environmentally friendly ways to remediate polluted environments.

  • Students will understand historical and modern day heavy metal toxicity issues within the environment.
  • Students will investigate challenges associated with remediating heavy metals in the environment.
  • Students will learn about types and sources of heavy metal contaminants in water and soil.
  • Students will understand the definition of LD-50 (50% lethal dose).
  • Students will calculate and complete a standard LD-50 lab with copper sulfate.
  • Students will remediate a contaminated solution of copper sulfate using phytoremediation.
  • Students will use copper tests to monitor water toxicity over time.
  • Water is not polluted unless it looks dirty.
  • Once water is polluted, there is no way to clean it again.
  • There are no metals in our water or soil.
  • The dose of something does not matter as long as it is good for you.
  • This lesson is divided into two parts, Part I and Part II. Part I involves an introduction to water pollution and heavy metal toxicity, followed by an LD-50 lab with blackworms. This part will involve small in-class activities and introductory lessons, and a follow-up case study for homework. Part II is the phytoremediation portion of the lab, and incorporates another small in-class lab and case studies during the duration of the multi-day lab.
  • Introduction to heavy metal toxicity in the environment through an in-class presentation and discussion of a case study.
  • Exploration of LD-50 through an introductory lesson and in-class lab activity.
  • Introduction to phytoremediation through an introductory lesson and in-class lab activity.
  • Continuation of the phytoremediation lab activity and in-depth understanding of water pollution by completing an AP style free response question.
  • Repeat of the LD-50 lab with the remediated solution and in-class follow-up activity.
  • This unit was designed for an AP Environmental Science class in San Diego, CA in their toxicity unit. This was designed for 5 separate 90 minute periods, but could be adapted to shorter periods by using the case studies and follow-up activities for homework. Students should have been introduced to water pollution before beginning this unit, and this lesson leads well into the unit on human impacts on the environment.
  • Each unit involves student assessment through in-class activities and discussions. Lab write-ups may be used for each lab a formal assessment tool, and the follow-up activity may also be used as a formal assessment tool for the students.
  • This unit has an overall lesson outline and 5E lesson plan to describe the order of each activity within the unit. Student labs and worksheets also have a teacher version with detailed instructions on materials and methods. Suggestions have been made in the Power Points where teachers can get students involved by discussing in-class, using small whiteboards as a group, etc… Teachers should continually check for understanding throughout the unit, and often ask students about their preconceptions before beginning each lesson.
  • In lesson 5 students will complete a follow-up activity that combines the lessons for part I and part II of this unit. Students can be graded on how well they incorporated the lessons learned about heavy metals and remediation strategies in the environment. Additional research may also be allowed for this activity if the follow-up is completed for homework.
  • Pollution (VI)- 25-30% of the AP Exam
    A (3) Water pollution
          - Types and sources
          - Causes and effects
          - Maintaining water quality
          - Water purification
    B (1) Hazards to human health
          - Acute and chronic effects
          - Dose-response relationships
    B (2) Hazardous chemicals in the environment
          - Cleanup of contaminated sites


Water pollution in India

Polluted runoff
Lesson Specifics
  • Time Frame: 5 class periods, 90 minutes each

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