Transcript 06_24. ppt
TODAY • Practice clicker use. • Define some basic terms: environment and ecosystem. • Consider scales and borders. • Introduce biogeochemical cycles. I can clearly define “ecosystem.” 100% 1. Yes 2. No 0% 1 2 ENVIRONMENT “The combination of all things and factors external to the individual or population of organisms in question.” SCALE • Scale: dimensions of space and time. Often used to refer to levels of biological organization – Example: Cell, tissue, organisms (bacteria, flea, cat, elephant), ecosystem, region, the globe • Patterns, processes, measurements • Why relevant? – Lots of knowledge about small scale things – Lots of questions about large scale processes & patterns NATIONAL ACADEMY OF SCIENCE • National Academy of Sciences is an honorific society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. – The NAS was signed into being by President Abraham Lincoln on March 3, 1863, …to keep pace with the growing roles that science and technology would play in public life. – National Research Council in 1916. The National Academy of Science names 8 “Grand Challenges” Which of the following was NOT named? 0% 100% 0% 1. Infectious Disease and the Environment 2. Invasive Species 3. Biological Diversity and Ecosystem Functioning 1 2 3 • Biogeochemical cycles • Biological diversity and ecosystem Functioning • Climate variability • Hydrologic forecasting • Infectious disease and the environment • Institutions and resource use • Land-use dynamics • Reinventing the use of materials Environmental Issues - NRC vs. KC Issue National Research Council King County 1 Biogeochemical cycles Water and watersheds,lawns, energy 2 Climate variability Floods, global warming info. KC Climate Plan 3 Biological diversity & ecosystem functioning Shorelines, wetlands, forests, salmon 4 Hydrological forecasting Floods, stormwater 5 Infectious diseases & the environment Noxious weeds, wastewater 6 Institutions and resource use Environmental services in King County 7 Land use dynamics Stewardship, dumps, regional planning, zoning atlas 8 Reinventing the use of materials Biosolids, recycling What is a system? • System: a collection of matter, parts, or components which are included inside a specified, often arbitrary, boundary. Example: Ecosystem • Systems often have inputs and outputs. • For dynamic systems, by definition, one or more aspects of the system change with time. – Example of a simple dynamic system: bathtub or your ‘bank’ account. • The boundary of a dynamic system is chosen for convenient conceptual separation for the system What are biogeochemical cycles? • Earth system has four parts – – – – Atmosphere Hydrosphere Lithosphere Biosphere • Biogeochemical cycles: The chemical interactions (cycles) that exist between the atmosphere, hydrosphere, lithosphere, and biosphere. • Abiotic (physio-chemical) and biotic processes drive these cycles What is common amongst them? • Each compound (water, carbon, nitrogen) typically exists in all four parts of the Earth System • There are – ‘Pools’ – Fluxes in and out of pools – Chemical or biochemical transformations • Transformations – are important – can lead to positive & negative consequences Transformations Examples of Transformations 1. Water cycle: Liquid water to water vapor (process: evaporation and evapo-transpiration) 2. Water cycle: Water vapor to liquid water (process: condensation) 3. Carbon cycle: Organic compounds to CO2 (processes: respiration, decomposition, or fire) 4. Carbon cycle: CO2 to organic compounds (process: photosynthesis) 5. Nitrogen cycle: N2 to NO3 (atmospheric nitrogen to plant utilizable nitrate) (process: N-fixation) 6. Nitrogen cycle: N2 to NH3 (plant utilizable ammonia) (process: Haber-Bosch Industrial N-fixation) Carbon Cycle 5000 http://www.epa.gov/climatechange/kids/carbon_cycle_version2.html Carbon Cycle Data 760 • Burning of fossil fuels • Land conversion • Cement • Role of Oceans • Role of terrestrial plants (trees & soils) Lithosphere Key Aspects of the Carbon Cycle • Carbon is the skeleton of all life. • Carbon dioxide is a critical gas: – Taken up by plants in photosynthesis – Released by plants and animals in respiration – Released during decomposition (and fires) – Greenhouse gas Question: Photosynthesis is an example of a pool 1. True 2. False 0% 1 Answer Now! 0% 2 10 Nitrogen Cycle www.britannica.com Nitrogen Cycle Forms & Sources of biologically available nitrogen (N2) For plants • NO3- (nitrate) • NH4+ (ammonium) • Sources: N-fixation by plants (N2 to NH3 and N2 to NO3), lightening, bacteria decomposition of organic N (amino acids & proteins) For animals • Organic forms: amino acids and proteins (from plants or other animals) Nitrogen Cycle Losses of nitrogen from system • In bogs, lakes (places of low oxygen), NO3- is converted to N2 by bacteria (get their oxygen from the NO3) • Volatilization of NH4+ (urea) to ammonia gas (NH3) warm, dry conditions. • Leaching of NO3- (nitrate) • Erosion • Fire (combustion) Nitrogen Sources over time Nitrogen Cycle: Key Points • Nitrogen is in the atmosphere as N2 (78%) • N2 is an inert gas and cannot be used by plants or animals • N2 can be converted to a usable form via – Lightening – N-fixing plants and cyanobacteria – Industrial process (energy intensive) • Nitrogen limits plant growth • Nitrogen is easily lost from biological systems Summary • • • • • • What are systems? What are biogeochemical cycles? Why are they important? What is common about them? Carbon and nitrogen cycles Future thinking