Lecture 2 Environmental Systems Dynamic change and glow across interfaces cycling Variation in time and space temporal and spatial scales Flows across interfaces and scales o Zones of abrupt change at difference spatial scales Molecular Cellular organism Size viruses mite salmon trees forests earth o Interfaces boundaries o Feedback systems controlling system balance and stability Negative Feedback system is stabilized by counteracting response to perturbation E g sweating countering something that could be harmful Positive Feedback an accelerating process in the same direction reinforced feedback tends to destabilize a system Methane fossil fuel used for heating energy trapped methane in ice bubbles up as arctic ocean warms warming leads to more warming Methane hydrate based ecosystem on Ocean floor Lecture 3 September 7 2011 Science of the Environment Holistic multi disciplinary direct applications to human nature relationships policy ethics IT HAS A HUMAN DIMENSION In the past it was viewed as descriptive value laden opinionated Empirical Investigations Observation experimentation data collection hypothesis or idea or generalization o REASONING from specific to general Predicting system behavior or a cause effect relationship often with if then statement o DEDUCTIVE REASONING go from general idea to Nature of a good hypothesis specific concise Some basis in current scientific understanding logical clear Can test with observations or experiments From scientist s ideas world view observed patterns in nature IF IT SURVIVES MANY ATTEMPTS TO FALSIFY with observation and experimentation then it becomes provisionally accepted Can lead to a THEORY a well tested explanation aren t weak Leads to proof with absolute certainty importance of reproducibility probability statistics What are implications for environmental policy made in the face of scientific uncertainty The Dead Flashlight science in action Sources of uncertainty Precision reproducibility of replicated data High precision if values are close to one another standard deviation low precision poor reproducibility values are not close to one another Accuracy is not the same a precision Accuracy closeness of measured value to true value Measurements could be precise but inaccurate Lecture September 9 2011 Cyanobacteria blue green algae and Calcite Crystals They fix CO2 to sugars PHOTOSYNTHESIS The fix N2 to NH4 NIROGEN FIXATION They form CaCO3 in same environment MINERAL FORMATION Two products of photosynthesis glucose and oxygen Lecture 5 September 12 2011 Peat Bog in Sweden accumulation of organic carbon Implications C sequestration accumulation in the land and climate change nonrenewable fuel source takes a long time to accumulate wetland protection and biome stability Pools and Flux Nitogen fixing nodules on soybean roots Nodules mostly bacteria and leghemoglobin protein spheres Enzyme nitrogenase September 14 2011 Solar Decathlon on Mall in DC Sept 23 October 2 Open 10 2 weekdays and 10 5 30 weekends Visit at least 2 houses go through and talk to students write a reflection paper 2 3 pages Marquee Lectures Sept 28 is the bay worth saving Nov 14 evolution of life o 5 pm in 1101 Biosciences Res Bldg How does agriculture co opt the carbon cycle We have enhanceed the kind of carbon that is fixed What is lactic acid Builds up when theres a lack of oxygen The acid degrades when the oxygen catches up again An example of a partially degraded carbon compound Why is photosynthesis central to energy flows in most ecosystems Important first step in sun energy transformation Where does atmospheric oxygen gas come from By product of photosynthesis Use both products of photosynthesis in cellular respiration sugar oxygen Haber Bosch Process Artificial Nitrogen Fixation to create fertilizer Fritz Haber 1868 1934 Process invented 1908 N2 g 3H2 g 2NH3 g Requires 400 degrees C and 200 atm pressure with Fe catalyst in industrial process VERY DIFFERENT FROM BIOLOGICAL ONE TAKES A LOT OF FOSSIL FUEL one reason why agriculture is so energy intensive Major process for fertilizer production a major category of energy consumption in conventional agriculture 50 more N fixed now by humans than by natural processes He was awarded the Nobel Prize controversial because he also helped to develop poison gases Iron catalyst Environmental Implications of Nitrification Nitrite is ephemeral in soils and nat l waters Nitrate is persistent both are soluble Concerns o Methemoglobinemia blue baby syndrome o Eutrophication of saline watrs by green algae Compare with blue green algae in fresh water Ex bay keep nitrates out of the bay algae Dead zones anaerobic bacteria that don t use oxygen o US drinking water standard to protect babies 10 mg nitrate N L ppm Lecture September 16 11 Nitrogen fixation ultimately becomes protein important for humans Foraminifera very small tiny shells that form Environmental Implications of Denitirification good in that nitrate gas wastewater or groundwater cleaned environmental engineer bad in that nitrogen is lost from soil e g from agricultural use by crops farmer N20 is a greenhouse gas absorbs infrared IR radiation from Occurs in wetlands poorly drained soils swamps and tidal earth marshes Biomes or Ecoregions Global Ecological Communities Fundamental Observation Similar ecosystems are found under similar conditions of o Latitude N S of equator o Continental position relative to seas and oceans o Elevation above sea level Climate topography and soil conditions determine plant community character Ecoregions of the Continents Mediterranean chaparral regions 30 45 degrees N S latitude o Western side of continental land masses o Low elevation o Wet winters and dry summers TEMPERATURE AND PRECIPITATION DETERMINANTS OF BIOME DISTRIBUTION Aral Sea Disaster o 1960 4TH largest lake on earth fisheries important o irrigated cotton in Soviet era 2 rivers now do not reach the Aral diversions took the water o poster child of environmental disaster o new desert salt beds lake may disappear polluted water and toxic dust but a huge environmental restoration process Fundamental Energy for Earth Energy sources solar kinetic and internal core Poles 40 as much solar energy as equator Heat transfer equator to poles Macroclimates would be in latitudinal bands determined by solar radiation Generalized zones for plant growth determined by temperature and latitude o Polar temperate tropical Moisture vs latitude Altitude vs Latitude o No particular pattern