EUTRO

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Massachusetts Institute of Technology *

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Jan 9, 2024

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LAB 15: AN INVESTIGATION OF Eutrophication Credit: USGS, Public domain AP Environmental Science Lab Manual STUDENT EDITION

PRIMARY TOPIC TOPIC 8.5 Eutrophication PRIMARY LEARNING OBJECTIVE STB-3.F Explain the environmental effects of excessive use of fertilizers and detergents on aquatic ecosystems. SECONDARY TOPICS TOPIC 5.4 Impact of Agricultural Practices TOPIC 8.2 Human Impacts on Ecosystems SECONDARY LEARNING OBJECTIVES EIN-2.D Describe agricultural practices that cause environmental damage. STB-3.B Describe the impacts of human activities on aquatic ecosystems. Materials § Spring or distilled water § Freshwater algae growth media § Chlorella sp. culture § Sodium nitrate solution § Potassium phosphate solution § 4 centrifuge or test tubes and rack § Permanent marker § Secchi stick § Luer lock syringe with 6 cm of aquarium tubing attached § Graduated cylinder Overview and Purpose This lab investigation is designed to help you understand that a body of water enriched with nutrients, such as nitrogen and phosphorus from human activities, can experience accelerated aquatic primary producer growth, triggering a series of events called eutrophication . § You will learn that eutrophication and the amount of suspended sediment in water will affect the water’s transparency. Measurement of transparency can serve as an early warning that human land use is having an effect on a body of water. § By the end of the lab , you will know that eutrophication can reduce the biodiversity of the communities of organisms that inhabit the bottom of both freshwater and marine environments, also known as benthic communities. You will grow algae using various nutrient treatments. Using a Secchi stick, you will measure the water transparency in algal samples to estimate algal cell density and calculate the percent change in algal cell density over the course of a week. PRE-LAB ACTIVITY Read the short HHMI BioInteractive article “One-third of America’s rivers have changed color since 1984.” Following an introduction from your teacher on how to interact with it, examine the interactive river map and answer the questions posed below. The article is available here: https://www.biointeractive.org/ planning-tools/science-news/one-third-americas-rivers-have-changed- color-1984 . The interactive map can be accessed here: https://cuahsi.shinyapps. io/RiverColor/ . PRE-LAB QUESTIONS Answer the following questions in your lab notebook. 1. Describe the dominant river color in the U.S. and what it implies about river water quality. 2. Two percent of U.S. rivers have shifted from yellow to green since 1984. a. What does this change in color imply about the water quality in the rivers? b. Describe the most common causes of color changes from yellow to green. 3. Only 5 percent of the rivers are blue, the color associated with pristine water. Open the interactive map and find an area where most rivers are blue. Click on the icon in the upper right to switch to the “Esri.WorldImagery” layer and view land use at the regional and local levels. Describe the land use near the blue rivers. Eutrophication: Eutrophication is the series of events that occur in a body of water as it becomes enriched with nutrients. When the nutrients that result in eutrophication enter the water as a result of human activities, it is referred to as cultural eutrophication. AP Environmental Science Lab Manual Eutrophication Lab 15 2 STUDENT EDITION

GETTING STARTED QUICKWRITE Write down your answers to the following question in your lab notebook after you have been given an overview of the lab by your teacher. Identify a testable hypothesis and scientific question for this lab investigation. Your Answers Matter: In order to be successful on the AP Exam, your answers to the free- response questions need to be thorough and detailed. It’s important that your responses include complete thoughts and comprehensive answers. Practicing this now will help you succeed on the AP Exam. AP Environmental Science Lab Manual Eutrophication Lab 15 3 STUDENT EDITION

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