Presentation on theme: "3 Environmental systems: Connections, energy, and ecosystems."— Presentation transcript:
3 Environmental systems: Connections, energy, and ecosystems
Key Terms acidic aquifers atoms autotrophs basic biogeochemical cycles biomass biomes carbohydrates carbon cycle cells cellular respiration chaparral chemical energy climate diagrams climatographs compound covalent bond dead zone denitrifying bacteria igneous rocks ionic bonds ionic compounds ions isotopes kinetic energy lava lipids macromolecules magma metamorphic rock molecules negative feedback loop net primary productivity neutrons nitrification nitrogen cycle nitrogen fixation deoxyribonucleic acid (DNA) desert ecosystem electrons elements energy entropy enzymes eukaryotic eutrophication evaporation feedback loop first law of thermodynamics groundwater Gulf of Mexico heterotrophs hydrocarbons hydrologic cycle hypoxia
Key Terms Continued nitrogen-fixing bacteria nucleic acids nutrient cycles nutrients organelles organic compounds phosphorus cycle photosynthesis plymers positive feedback loop potential energy precipitation primary producers primary productivity prokaryotic proteins protons ribonucleic acid (RNA) rock cycle runoff salts savannas second law of thermodynamics sedimentary rock sediments system taiga temperate deciduous forest temperate grasslands temperate rainforest transpiration tropical dryforest tropical rainforest tundra
The Ecology of the Environment: The nature of systems Ecosystem-level ecology Earth’s biomes Nutrient cycles: Nitrogen, Carbon, Phosphorus The rock cycle The hydrologic cycle
Central Case: The Gulf of Mexico’s “Dead Zone” Major fisheries off Louisiana were devastated by die-offs. Scientists found large regions of low oxygen in the Gulf. The recurring “dead zone” resulted from nitrogen pollution traveling down the Mississippi River.
Earth’s environmental systems Our planet consists of many complex, large-scale, interacting systems. System = a network of relationships among a group of parts, elements, or components that interact with and influence one another through the exchange of energy, matter, and/or information Feedback loop = a circular process whereby a system’s output serves as input to that same system.
Feedback loops: Negative feedback In a negative feedback loop, output acts as input that moves the system in the opposite direction. This compensation stabilizes the system Figure 6.1a
Feedback loops: Positive feedback In a positive feedback loop, output acts as input that moves the system further in the same direction. This magnification of effects destabilizes the system. Figure 6.1b
An environmental system Mississippi River as a system: Input of water, fish, pollution, etc. Output to Gulf of Mexico Figure 6.3
Two systems or one? The Mississippi River system and the system of the Gulf of Mexico interact. Understanding the dead zone requires viewing the Mississippi River and the Gulf of Mexico as a single system. This holistic kind of view is necessary for comprehending many environmental issues and processes.
Eutrophication Key to the dead zone = Eutrophication: excess nutrient enrichment in water, which increases production of organic matter... … which when decomposed by oxygen-using microbes can deplete water of oxygen
Creation of the hypoxic dead zone Nitrogen input boosts phytoplankton… …which die and are decomposed by microbes that suck oxygen from water, killing fish and shrimp. Figure 6.5
Ways To Organize Nature Emergent Properties Classification Trophic Structures
Emergent Properties When units, particles, or moieties at one level of organization are place together in unique combinations to form a new unit, particle, or moiety at a higher level of organization, the new properties emerge.
Chemistry and the environment Chemistry is central to environmental science: Carbon dioxide and climate change Sulfur dioxide and acid rain Pesticides and public health Nitrogen and wastewater treatment Ozone and its atmospheric depletion
Atoms and elements An element is a fundamental type of chemical substance. Elements are composed of atoms. Each atom has a certain number of: protons (+ charge) electrons (– charge) neutrons (no charge) Figure 4.1
Atoms and elements 92 elements occur in nature, each with its characteristic number of protons, neutrons, and electrons. Figure 4.1
Chemical symbols Each element is abbreviated with a chemical symbol: H = hydrogen C = carbon N = nitrogen O = oxygen P = phosphorus Cl = chlorine Fe = iron CHOPKINS CaFe
Isotopes Isotopes are alternate versions of elements, which differ in mass by having a different number of neutrons. Carbon-14 has two extra neutrons beyond normal carbon’s 6. Figure 4.2
Ions Atoms electrically charged, due to gain or loss of electrons Figure 4.3
Molecules, compounds, and bonds Molecules = combinations of two or more atoms Compounds = molecules consisting of multiple elements Atoms are held together by bonds: covalent bond = uncharged atoms sharing electrons (CO 2 ) ionic bond = charged atoms held together by electrical attraction (NaCl)
Water is a unique compound Hydrogen bonds give water properties that make it a vital molecule for life: Is cohesive Resists temperature change Ice insulates Dissolves many chemicals Figure 4.4
Acidity In an aqueous solution, If H + concentration is greater than OH – concentration, then solution is acidic. If OH – is greater than H +, then solution is basic.
pH scale pH scale measures acidity and basicity. Pure water = 7 Acids < 7 Bases > 7 Figure 4.6
Organic compounds Consist of carbon atoms and, generally, hydrogen atoms Joined by covalent bonds May include other elements Highly diverse; C can form many elaborate molecules Vitally important to life ethane
Hydrocarbons C and H only; major type of organic compound Mixtures of hydrocarbons make up fossil fuels. Figure 4.7
Macromolecules Large molecules essential for life: Proteins Nucleic acids Carbohydrates Lipids The first three are polymers, long chains of repeated molecules.
Proteins Consist of chains of amino acids; fold into complex shapes For structure, energy, immune system, hormones, enzymes Figure 4.8
Carbohydrates Complex carbohydrates consist of chains of sugars. For energy, also structural (cellulose, chitin) Figure 4.11
Lipids Do not dissolve in water Fats and oils Phospholipids Waxes Steroids
Nucleic acids DNA and RNA Encode genetic information and pass it on from generation to generation DNA = double-stranded chain (double helix) RNA = single-stranded chain
Nucleic acids Paired strands of nucleotides make up DNA’s double helix. Figure 4.9
Genes and heredity Genes, functional stretches of DNA, code for the synthesis of proteins. Figure 4.10
Cells Basic unit of organismal organization; compartmentalize macromolecules and organelles Figure 4.12 Eukaryotic cell Animal cell Plant cell Prokaryotic cell
Energy Can change position, physical composition, or temperature of matter Potential energy = energy of position (water held behind a dam) Kinetic energy = energy of movement (rushing water released from a dam)
Potential and kinetic energy Potential energy stored in food is converted to kinetic energy when we exercise. Figure 4.13
Electromagnetic Energy Sun High energy, short wavelength Low energy, long wavelength Ionizing radiation Nonionizing radiation Cosmic rays Gamma rays X rays Far ultraviolet waves Near ultraviolet waves Visible waves Near infrared waves Far infrared waves Microwaves TV waves Radio waves Wavelength in meters (not to scale) 10 - 14 10 - 12 10 - 8 10 - 7 10 - 6 10 - 5 10 - 3 10 - 2 10 - 1 1
Energy Distribution in Sunlight Energy emitted from sun (Kcal/cm 2 /min) 0 5 10 15 0.25122.53 Wavelength (micrometers) Visible Infrared Ultraviolet Energy Distribution in Sunlight Energy emitted from sun (Kcal/cm 2 /min) 0 5 10 15 0.25122.53 Wavelength (micrometers) Visible Infrared Ultraviolet
Energy Quality High Quality Solid Salt Coal Gasoline Aluminum can Low Quality Gas Solution of salt in water Coal-fired power plant emissions Automobile emissions Aluminum ore
Transmission of Energy ConvectionConductionRadiation Heating water in the bottom of a pan causes some of the water vaporize into bubbles. Because they are lighter than the surrounding water, they rise. Water then sinks from the top to replace the rising bubbles. This up and down movement (convection) eventually heats all of the water. Heat from a stove burner causes atoms or molecules in the pan’s bottom to vibrate faster. The vibrating atoms or molecules then collide with nearby atoms or molecules, causing them to vibrate faster. Eventually, molecules or atoms in the pan’s handles are vibrating so fast it becomes too hot to touch. As the water boils, hear from the hot stove burner and pan radiate into the surrounding air, even though air conducts very little heat.
Energy Quality Electricity Very–high-temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Dispersed geothermal energy Low-temperature heat (100°C or lower) Very high High Moderate Low Source of Energy Relative Energy Quality (usefulness) Energy Tasks Very–high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) Mechanical motion (to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Low-temperature heat (100°C or less) for space heating
Relationship between Energy Quality and Pollution Streams Inputs (from environment) High-quality energy Matter System Throughputs Output (intro environment) Unsustainable high-waste economy Low-quality energy (heat) Waste matter and pollution
Laws of thermodynamics First Law: Energy can change form, but cannot be created or lost. Second Law: Energy will tend to progress from a more- ordered state to a less-ordered state (increase in entropy).
Increase in entropy Burning firewood demonstrates the second law of thermodynamics. Figure 4.14
Energy from the sun Energy from the sun powers most living systems. Visible light is only part of the sun’s electromagnetic radiation. Figure 4.15
Autotrophs and photosynthesis The sun’s energy is used by autotrophic organisms, or primary producers (e.g., plants), to manufacture food. Photosynthesis turns light energy from the sun into chemical energy that organisms can use.
Photosynthesis In the presence of chlorophyll and sunlight, Water and carbon dioxide are converted to sugars and oxygen. Figure 4.16
Photosynthesis 6 CO 2 + 12 H 2 O + energy from sun ————> C 6 H 12 O 6 (sugar) + 6 O 2 + 6 H 2 O
Streamlined 6 CO 2 + 6 H 2 O + energy from sun ————> C 6 H 12 O 6 (sugar) + 6 O 2
Respiration and heterotrophs Organisms use stored energy via respiration, which splits sugar molecules to release chemical energy. This occurs in autotrophs and in the heterotrophs (animals, fungi, most microbes) that eat them.
Respiration The equation for respiration is the exact opposite of the equation for photosynthesis. Some organisms and communities live without sunlight and are powered by chemosynthesis. C 6 H 12 O 6 (sugar) + 6 O 2 ————> 6 CO 2 + 6 H 2 O + chemical energy
Ecosystems Ecosystem = all the interacting organisms and abiotic factors that occur in a particular place and time Energy and nutrients flow among all parts of an ecosystem. Conception of an ecosystem can vary in scale: small pond large forest entire planet
Energy in ecosystems Energy from sun converted to biomass (matter in organisms) by producers through photosynthesis Rapid conversion = high primary productivity (coral reefs) Rapid plant biomass availability for consumers = high net primary productivity (wetlands, tropical rainforests)
Flow of Energy in Ecosystems Solar energy Waste heat Chemical energy (photosynthesis) Waste heat Waste heat Waste heat Chemical energy (food) Mechanical energy (moving, thinking, living)
Nutrient (biogeochemical) cycles These describe how particular chemicals cycle through the biotic and abiotic portions of our environment. Nutrients = elements and compounds organisms consume and require for nutrition and survival A carbon atom in your body could have been part of a dinosaur 100 million years ago.
Nutrient (biogeochemical) cycles Nitrogen, carbon, and phosphorus are key nutrients. Nitrogen: 78% of atmosphere In proteins and DNA In limited supply to organisms; requires lightning or bacteria to become usable A potent fertilizer Carbon: Key component of organic molecules Atmospheric CO 2 regulates climate Phosphorus: In ADP and ATP for metabolism In DNA and RNA In limited supply to organisms A potent fertilizer
The nitrogen cycle How nitrogen (N) moves through our environment Atmospheric N 2 is fixed by lightning or specialized bacteria and becomes available to plants and animals in the form of ammonium ions (NH 4 + ). Nitrifying bacteria turn ammonium ions into nitrite (NO 2 – ) and nitrate (NO 3 – ) ions. Nitrate can be taken up by plants. Animals eat plants, and when plants and animals die, decomposers consume their tissues and return ammonium ions to the soil. Denitrifying bacteria convert nitrates to gaseous nitrogen that reenters the atmosphere.
Human impacts on the nitrogen cycle Haber and Bosch during WWI developed a way to fix nitrogen artificially. Synthetic nitrogen fertilizers have boosted agricultural production since then. Today we are fixing as much nitrogen artificially as the nitrogen cycle does naturally. We have thrown the nitrogen cycle out of whack.
Human impacts on the nitrogen cycle Figure 6.26
Nitrogen and the dead zone Excess nitrogen flowing down the Mississippi River into the Gulf causes hypoxia, worse in some regions than others. From The Science behind the Stories
Nitrogen and the dead zone The size of the hypoxic zone in the northern Gulf of Mexico, had grown since 1985, and was largest in 2002. From The Science behind the Stories
Viewpoints: The dead zone Terry Roberts Paul Templet “The Dead Zone is driven by a massive influx of nutrients into a system no longer able to process them. … We need to act now to save these resources.” “Evidence that nitrogen fertilizer is polluting the Gulf of Mexico is not conclusive… Used correctly, fertilizer increases food production and helps protect the environment.” From Viewpoints
The carbon cycle How carbon (C) moves through our environment Producers pull carbon dioxide (CO 2 ) from the air and use it in photosynthesis. Consumers eat producers and return CO 2 to the air by respiration. Decomposition of dead organisms, plus pressure underground, forms sedimentary rock and fossil fuels. This buried carbon is returned to the air when rocks are uplifted and eroded. Ocean water also absorbs carbon from multiple sources, eventually storing it in sedimentary rock or providing it to aquatic plants.
Human impacts on the carbon cycle We have increased CO 2 in the atmosphere by burning fossil fuels and deforesting forests. Atmospheric CO 2 concentrations may be the highest now in 420,000 years. This is driving global warming and climate change.
The phosphorous cycle How phosphorus (P) flows through our environment. P is most abundant in rocks. Weathering releases phosphate (PO 4 3– ) ions from rocks into water. Plants take up phosphates in water, pass it on to consumers, which return it to the soil when they die. Phosphates dissolved in lakes and oceans precipitate, settle, and can become sedimentary rock.
The hydrologic cycle How water flows through our environment Water enters the atmosphere by evaporation and by transpiration from leaves. It condenses and falls from the sky as precipitation. It runs off the land surface into streams, rivers, lakes, and eventually the ocean. Water infiltrates into aquifers, becoming groundwater.
The rock cycle A key environmental system Rocks change from one form to another over time Igneous rock = of volcanic origin; cooled magma Sedimentary rock = mineralized sediments (layers of mud, dust, or sand) Metamorphic rock = transformed by extreme heat or pressure
Biomes Biome = major regional complex of similar plant communities A large ecological unit defined by its dominant plant type and vegetation structure Biomes are determined primarily by a region’s climate, esp. temperature and precipitation.
Climate and biomes Biomes change with temperature and precipitation. Figure 6.8
Climatographs These climate diagrams show monthly temperature and precipitation variation for a particular site. Climate patterns tend to be similar within a given biome. Figure 6.10
Temperate deciduous forest Temperature moderate, seasonally variable Precipitation stable through year Trees deciduous: lose leaves in fall, dormant in winter Moderate diversity of broad-leafed trees North America, Europe, China Figure 6.9
Temperate grassland Temperature moderate, seasonally variable Precipitation sparse but stable Grasses dominate; few trees Large grazing mammals North America, Asia, South America Figure 6.10
Temperate rainforest Temperature moderate Precipitation very high Trees grow tall Dark moist forest interior Pacific northwest region of North America, Japan Figure 6.11
Tropical rainforest Temperature warm, seasonally stable Precipitation high Trees tall; forest interior moist and dark Extremely high biodiversity Soil poor in organic matter; is aboveground Equatorial regions Figure 6.12
Tropical dry forest Temperature warm, seasonally stable Precipitation highly seasonally variable Trees deciduous: dormant in dry season High biodiversity Subtropical latitudes Figure 6.13
Savanna Temperature warm Precipitation highly seasonally variable Grassland interspersed with trees Large grazing mammals Africa and other dry tropical regions Figure 6.14
Desert Figure 6.15 Temperature warm in most, but always highly variable b/w day and night Precipitation extremely low Vegetation sparse; growth depends on periods of rain Organisms adapted to harsh conditions Southwestern region of North America, Australia, Africa
Tundra Temperature cold, seasonally variable Precipitation very low Vegetation very low and sparse; no trees Low biodiversity; high summer productivity Arctic regions Figure 6.16
Taiga (boreal forest) Temperature cool, seasonally variable Precipitation low to moderate Coniferous (evergreen) trees dominate; monotypic forests Low biodiversity; high summer productivity Subarctic regions Figure 6.17
Chaparral Temperature seasonally variable Precipitation seasonally variable Evergreen shrubs dominate Plants resistant to fire; burns frequently California, Chile, West Australia Figure 6.18
Aquatic “biomes” Aquatic systems also show patterns of variation and can be categorized like biomes. But the “biome” concept has historically been applied to terrestrial systems. Aquatic systems are shaped not by air temperature and precipitation, but by water temperature, salinity, dissolved nutrients, currents, waves, etc.
Conclusions: Challenges The Gulf of Mexico’s dead zone threatens coastal ecosystems and fishing economies. We are depleting groundwater supplies. We have doubled Earth’s nitrogen fixation. We have increased CO 2 concentrations in the atmosphere. An understanding of chemistry is crucial to many questions in environmental science. An understanding of energy fundamentals is important for ecology and human use of energy resources.
Conclusions: Solutions Decreasing fertilizer application and finding other ways to lessen nitrogen runoff into the Mississippi River should mitigate the dead zone. Conservation, desalination, and equitable distribution are solutions to groundwater depletion. Modifications in the way we pursue agriculture can reduce artificial nitrogen fixation. Reducing fossil fuel use and forest loss can reverse CO 2 enrichment of the atmosphere. Energy fundamentals inform our understanding of ecology and human use of energy resources.
QUESTION: Review Which biome has warm stable temperatures, highly seasonal rainfall, deciduous trees, and high biodiversity? a.Tropical rainforest b.Tropical dry forest c.Temperate rainforest d.Taiga
QUESTION: Review Water enters the atmosphere through the process of…? a.Precipitation b.Transpiration c.Infiltration d.Runoff
QUESTION: Review Carbon enters the atmosphere as carbon dioxide when… ? a.Animals respire. b.Sedimentary rocks are uplifted and eroded. c.Humans burn fossil fuels. d.All of the above take place.
QUESTION: Weighing the Issues If farmers’ use of fertilizers affects shrimp fishermen far downstream, who should be responsible for developing policies to address the problem? a.Governments of the farming states upstream b.Governments of the fishing states downstream c.The federal government d.Both state and federal governments
QUESTION: Interpreting Graphs and Data In this climatograph for Los Angeles, California, in the chaparral biome, summers are… ? a.Warm and dry b.Warm and wet c.Mild and dry d.Mild and wet Figure 6.18
QUESTION: Interpreting Graphs and Data Nitrogen inputs from fertilizer…? a. Have decreased since 1950. b. Are less than inputs from animal manure. c. Equal 8 million metric tons/year. d. Became the primary nitrogen source in the 1960s. Figure 6.26
QUESTION: Viewpoints What should be done about the Gulf of Mexico’s dead zone? a. Mandate that Midwestern farmers reduce use of fertilizers. b. Work with Midwestern farmers to find ways to lessen fertilizer runoff. c. Nothing yet; more research is needed to determine the causes of the hypoxia.
QUESTION: Review Which of the following is a heterotroph? a.Pine tree b.Photosynthetic algae c.Squid d.Hydrogen sulfide
QUESTION: Review The second law of thermodynamics states that…? a.Energy cannot be created or destroyed b.Things tend to move toward a less-ordered state c.Matter tends to remain stable d.Potential and kinetic energy are interchangeable
QUESTION: Interpreting Graphs and Data A molecule of the hydrocarbon ethane contains…? Figure 4.7 a. 2 carbon atoms and 6 hydrogen atoms b. 2 carbon molecules and 6 hydrogen enzymes c. Carbon and hydrogen DNA d. Eight different isotopes
QUESTION: Interpreting Graphs and Data Which is listed from most acidic to most basic? a. Ammonia, baking soda, lemon juice b. Stomach acid, soft soap, HCl c. Acid rain, NaOH, pure water d. HCl, acid rain, ammonia Figure 4.6