Lecture VIIILecture IX AP Environmental Science By Dr. Woodward
AP Environmental Exam • The AP Environmental Science Exam covers a one-semester introductory college course in environmental science with laboratory. • The questions included in Section I are designed to cover the breadth of students' knowledge and understanding of environmental science. • There are four questions in Section II. One is a data-set question, which requires students to analyze and interpret a given set of data. One is a document-based question in which students answer questions related to a given document (such as a pamphlet, advertisement, or newspaper article) and apply their knowledge of environmental science to contexts that are current, relevant, and authentic. • Two are synthesis questions, which are in-depth, often multi-part essays.
AP Environmental Exam • T h e Exam • The AP Environmental Science Exam is 3 hours long and is divided equally in time • between a multiple-choice section and a free-response section. The multiple-choice • section, which constitutes 60 percent of the final grade, consists of 100 multiple-choice • questions that are designed to cover the breadth of the students’ knowledge and • understanding of environmental • science. Thought-provoking problems and questions • based on fundamental ideas from environmental science are included along with • questions based on the recall of basic facts and major concepts. The number of • multiple-choice questions taken from each major topic area is reflected in the • percentage of the course as designated in the topic outline (see pages 6–9). • The free-response section emphasizes the application of principles in greater depth. • In this section, students must organize answers to broad questions, thereby • demonstrating reasoning and analytical skills, as well as the ability to synthesize • material from several sources into cogent and coherent essays. • Four free-response questions are included in this section, which constitutes 40 percent of the final grade: • 1 data-set question, 1 document- • based question, and 2 synthesis and evaluation
Lecture VIII: Today’s Agenda: Journal Question: What is a heavy metal? *Lecture VIII “Hazardous Chemicals & Heavy Metals” Exam I this Friday
The Nature of Chemical Hazards • A chemical that presents a certain hazard or risk is known as a hazardous material (HAZMAT) • The EPA categorizes substances on the basis of the following criteria: (1) Ignitability (2) Corrosivity (3) Reactivity (4) Toxicity
Ignitability • Substances that catch fire readily. (1) Gasoline, Alcohol
Corrosivity • Substances that corrode storage tanks and equipment. (1) Acids
Reactivity • Substances that are chemically unstable and that may explode or create toxic fumes when mixed with water. (1) Explosives, elemental phosphate, and concentrated sulfuric acid
Toxicity • Substances that are injurious to health when they are ingested or inhaled. (1) Chlorine, Ammonia, Pesticides, Formaldehyde
HAZMAT Notification A. Containers in which HAZMAT’s are stored and vehicles that carry HAZMAT’s are required to display place cards that identify hazards.
The Threat of Toxic Chemicals A. All toxic chemicals, by definition, are hazards that pose risk to humans.
Two Major Classes of Chemicals • These chemicals do not readily degrade in the environment. (1) Heavy Metals & Their Compounds (2) Synthetic Organics
Heavy Metals A. The most dangerous heavy metals are lead, mercury, arsenic, cadmium, tin, chromium, zinc, and copper.
Heavy Metals B. These metals are used widely in industry, particularly in metal working or metal-plating shops and in such products as batteries and electronics. (1) Can also be paint pigments, glazes, inks and dyes.
Heavy Metals C. Case Study: Mercury in Fish (1) Federal Study Shows Mercury in Fish Widespread (2010) a. Mercury contaminated fish in 300 streams tested across the country. b. Only 1/4 of these fish had levels of mercury that exceed the EPA’s safe level
Heavy Metals D. Heavy metals are extremely toxic because, as ions or in certain compounds, they are soluble in water and may be readily absorbed into the body. (1) They can combine and inhibit the functioning of particular vital enzymes.
Heavy Metals E. Even very small amounts can have severe physiological or neurological consequences. (1) Lead poisoning can cause mental retardation and insanity. (2) Mercury poisoning can cause crippling birth defects.
Synthetic Organics • Petroleum-derived and synthetic organic compounds are the chemical basis for all: (1) Plastics (2) Synthetic Fibers (3) Synthetic Rubber (4) Solvents *(5) Pesticides (6) Hundreds of other products!!!
Synthetic Organics B. Because of their chemical structure, many synthetic organics are resistant to biodegradation.
Synthetic Organics C. They are toxic because they are often readily absorbed into the body, where the interfere with particular enzymes. (1) When they accumulate in the body, the effect may be acute poisoning and death.
Pesticides: DDT • DDT is the first and most widely used of the synthetic organic pesticides
Lecture IX: Acid in Freshwater Lakes Journal Question: Give an example of the two major classes of harmful chemicals. *1. Lecture IX: Acids & Freshwater Lakes -AP Exam Essay Component- 2. Study for Exam I
Echo Park In 1868, the lake was formed to provide a source of drinking water or drinking water storage.
Echo Park Lake (9/28/2011) It was found that in 2006 the lake that once provided drinking water now contains… Copper, Ammonia, Algae, Lead, PCB’s and low levels of oxygen (DO) that we briefly discussed during our last lecture on pollutants. -The sludge at the bottom of the lake will be hauled off to landfills. -The draining of this lake began this September, which is now!
Problems with Lake Acidification • As pH levels decline, the biodiversity decreases. • As acidity decreases, the biodiversity increases. • As pH values increase, the biodiversity increases. -Fresh water fish cannot live in an acidic environment-
Chemical, Physiological, and Ecological Factors Effected by Lake Acidification • Toxic (heavy, harmful) metals (such as Al, Pb, Cd, Cu, Fe, methyl mercury) are released into solution lower the pH levels. Mercury inhibits the production of myelin a. Myelin surrounds nerves. b. Symptoms effect the nervous system.
Chemical, Physiological, and Ecological Factors Effected by Lake Acidification 2. Increased nitrogen levels stimulate plant growth resulting in an algal blooms.
Chemical, Physiological, and Ecological Factors Effected by Lake Acidification 3. There is increased death and decomposition resulting in lower dissolved oxygen (DO) levels.
Chemical, Physiological, and Ecological Factors Effected by Lake Acidification 4. Reduced photosynthesis (due to plant death) leads to reduced levels of dissolved oxygen (DO).
Chemical, Physiological, and Ecological Factors Effected by Lake Acidification 5. *Acids interfere with enzyme activity. 6. Acids also cause tissue damage. 7. Eggs unlikely to survive in an acidic environment. 8. Acids cause bone decalcification and interferes with calcium uptake. 9. Disrupts muscle contraction (Calcium is an important component in muscle contraction)
Causes of Lake Acidification • Recall: A lake is a fresh water ecosystem. 1. Sulfur dioxide (S02)in the atmosphere reacts with atmospheric gases (oxygen and water vapor) to produce sulfuric acid (acid deposition) –Acid Rain
Causes of Lake Acidification • Recall: A pH below 7 is acidic, above 7 is basic. 2. Organic acids and metallic cationsin leachate flow into a lake from leaking sanitary landfills.
Leachate Leachate is the mixture of water and materials (i.e. chemicals) that are leaching. Leaching is the process in which the materials in or on the soil gradually dissolve and are carried by water seeping through the soil.
Leaching • Leaching may eventually remove valuable nutrients from the soil, or it may carry buried wastes into groundwater, thereby contaminating it.
Causes of Lake Acidification 3. Hydrochloric or sulfuric acid industrial wastes are discharged into a watershed (point source pollution)
Causes of Lake Acidification 4. NO2 in the atmosphere reacts with atmospheric gases (oxygen and water vapor) to produce nitric acid (acid deposition) –Acid Rain-
Prevent Lake Acidification Potential ways to avoid or remediated lake acidification. As it relates to -Sulfur Dioxide- • Reduce fossil fuel use. • Install air pollution device. • *Develop and use alternative (non-fossil fuel) energy sources.
Prevent Lake Acidification • As it relates to leaching: • Monitor, collect and chemically treat leachate. • *Construct and operate sanitary landfills following strict guidelines.