Climate change bio
Terms
undefined, object
copy deck
- atmosphere (waaay back)
-
Originally similar to sun
⬢ Dominated by
o Hydrogen and helium
o Small amounts of methane, water vapor, ammonia, CO2, and gaseous nitrogen
Slowly things began to change
⬢ Hydrogen and helium disappear (small molecule mass)
⬢ Short wave UV radiation began to decompose H2O and NH3
o Resulted in more O2 and N2
- Volcanoes become a factor
-
⬢ Eruptions release
o CO2
o Water vapor
o N2
o Sulfur
o Volcanic ash
- ozone develops, and O becomes available
-
Ozone layer developed
⬢ O3 layer developed as the stratosphere formed
⬢ Provided a shield from harmful UV radiation and allowed life forms to develop
Photosynthesis arrives as O2 becomes more abundant
⬢ The evolution of photosynthesizing organisms became possible
o Cyanobacteria
o Algae
o Plants
- then comes humans
-
⬢ Human activities
o Discovery of fire for heating and cooking
o Development of villages and towns
o Development of organized agriculture
o Population growth
o Habitat destruction
o Pollution
⬢ Industrial revolution
o In 300 years there have been increases in
⬢ CO2 and H2O vapor
⬢ Methane
⬢ Sulfur and Nitrogen
⬢ Ozone (photochemical oxidant cycle)
⬢ Synthetic chemicals
- Troposphere
-
o 8-12 km up from the earths surface
o temperature decreases with height
o unstable turbulence, thermal energy
o weather is found here, occurs when cold and warm fronts interact
- stratosphere
-
o 12-48 km
o contains the ozone layer
⬢ relatively stable region
⬢ few clouds, horizontal ⬦?
⬢ Temperature increases with height
-
Assessing the Effects of Air Pollutants
Plants and Air Pollutants -
⬢ Most more responsive than humans at lower concentrations
⬢ Easier to work with, large numbers can be used
⬢ Better data bases are available for dose/response than for humans
-
Assessing the Effects of Air Pollutants
Pollutant uptake by plants -
⬢Via stomata
o Gases taken up during gas exchange in photosynthesis
⬢Via cuticle
o Wet and dry deposition of gases, ions and particles
⬢Via soil
o Uptake by xylem from soil
-
Assessing the Effects of Air Pollutants
Plant Responses -
⬢Acute injury
o Necrosis, visible
o Usually means high exposure/short time
⬢Chronic injury
o Chlorosis, pigmentation
o Usually means low levels/long time
⬢Growth responses
o Measurable effects on growth/reproduction
o Combination of acute/chronic
-
Assessing the Effects of Air Pollutants
Effects Detection Approaches -
⬢Reductionist
o Full control, not natural, dose/response
⬢Semi-reductionist
o Less control, more natural, dose/response
⬢Natural conditions
o Ambient, little control, natural, no dose/response
-
Assessing the Effects of Air Pollutants
Effects Detection Approaches (more in depth) -
Reductionist Approach
⬢ Grow plants under controlled conditions
Semi-reductionist
⬢ Chambers of various types
⬢ Open air fumigation systems
Natural Exposure
⬢ bioindicators
⬢ Fields plots
⬢ Potted plants in a the field
⬢ Concentration gradients
⬢ Tolerant vs. sensitive plants
⬢ Antioxidant chemicals
-
Assessing the Effects of Air Pollutants
Bioindicators and biomonitors -
⬢Bioindicators
o Qualitative assessment
o Something has happened
⬢Biomonitors
o Quantitative assessment
o Dose/response approximated
-
Assessing the Effects of Air Pollutants
Types of Bioindicators and Biomonitors -
⬢Sentinels
o Known sensitive organisms introduced into an area
⬢Early warning: local monitoring abatement
⬢Require special care
o Tobacco plants are bioindicators
⬢Detectors
o Naturally occurring species that may show a response
⬢Ecologically significant
⬢Locally important
o Indigenous plants
⬢ Exploiters
o Presence indicates disturbance and or pollution
⬢Abundance indicates due to lack of competition
o Stinging nettles
⬢Accumulators
o Take up and accumulate chemicals
⬢Can be measure
⬢Quantitative
o Lichens
⬢Bioassays
o Plants used for lab assays
⬢ Biochemical analyses
⬢ Physiological responses
-
Environmental Molecular Epidemiology
Biomarkers -
⬢ Molecular biomarkers
⬢ Tools of molecular analysis
⬢ Changes in DNA
⬢ Leading to
o Susceptibility
o Exposure
o Early disease incidence
-
Environmental Molecular Epidemiology
Promise of Biomarkers -
⬢ Early detections of disease
o Catch it while it is still reversible
o Before the damages are permanent
⬢ Custom-managed treatment
⬢ Difficult to identify with other confounding variables
-
Environmental Molecular Epidemiology
PAHs -
⬢ Polycyclic aromatic hydrocarbons
⬢ Incomplete combustion
o Coal Fossil fuels
o Cigarettes
⬢ Widespread
-
Environmental Molecular Epidemiology
Epigenetics -
⬢ A different kind of biomarker
⬢ Heritable environmentally induced
o The environment almost activates these genes, so its induced but inherited
⬢ Changes in gene function
⬢ Mutations in DNA code letters
⬢ PAHs appear to be involved
⬢ Different than DNA adducts
-
Environmental Molecular Epidemiology
DNA Methylation -
• Attachment of methyl groups to DNA
• “silences†genes
• prevents protein synthesis
• decreases disease suppression
-
Nitrogen
Constructing the Nitrogen Cycle
⬢ Under Natural Conditions
-
⬢ Aerial sources
o Fixation of N2 from air
o Inorganic N from rain, lightning, volcanoes
o Ammonia from air
⬢ Uptake by plants and soil
⬢ Wind blown aerosols with N forms
⬢ Terrestrial events
o Ammonia or nitrates taken up by plants used for amino acids
o Animal wastes, dead plants and animals broken down by bacteria and fungi to release ammonia
- Human Interference disrupts the equilibrium of the Nitrogen Cycle
-
⬢ Human energy requirements are met by combustion
o Natural gas
o Oil
o Coal, wood, plant biomass
⬢ This releases
o CO2
o VOC
o Nitrogen compounds
- Nitrogen Emissions to the Troposphere and stratosphere
-
⬢ Oxidized N fro fossil fuel combustion
o NO and NO2
⬢ Reduced N
o NH3
⬢ Agriculture
Animal excrement
Fertilizer
⬢ Wildlife
Animal excrement
- Nitric oxide NO
-
o Released by microbial actions on fertilizer on and in soil
o Active in the photochemical oxidant cycle
⬢ E.g. ozone formation - Global Population and the Nitrogen Cycle
-
⬢ Until the 20th century
o Nitrogen availability limited crop production and restricted population growth
⬢ The synthesis of ammonia and resulting abundance of nitrogen fertilizer changed all that
⬢ The availability of ammonia and fertilizers derived from it has eliminated a fundamental restriction on food production and allowed massive increases in population
- Harber-Bosch Synthesis of Ammonia
-
Ammonia is formed when nitrogen and hydrogen are combined at high pressure and high temperatures in the presence of the catalysts osmium and uranium
- Ammonia and Fertilizers
-
⬢ Ammonia can be used directly as a fertilizer or as ammonium nitrogen
⬢ Or used to make nitrate nitrogen fertilizers
⬢ Making fertilizers from ammonia requires electricity generated by combustion of fossil fuels
- Nitrous Oxide in the Air
-
⬢ Bacteria in soil break down nitrates and release N2O into the air
⬢ Molecules are long lasting and act as reradiative gases
o 200 times more absorbent than CO2
⬢ N2O migrates slowly to stratosphere reacts with O3 and destroys it
- sulfur Behavior in Air
-
⬢ Sulfate particles, SO2 and H2S
o H2S -> SO2 -> SO4 dry deposition
o S->SO2->SO3 +H2O->H2SO4 wet deposition
- Sulfur Removal from Air
-
⬢ Sulfur is recirculated to land and sea by
o Precipitation
⬢ Wet deposition
o Particle settling
⬢ Dry deposition
⬢ Plant foliage and moist soil can also remove SO2 directly from air
- Human Input of Sulfur
-
⬢ Combustion of fossil fuels
o Power plants
o Home heating
o Vehicles
o Manufacturing
⬢ Petroleum refining
⬢ Metal smelting
⬢ Acid drainage from mines
- Sulfur Dioxide SO2
-
⬢ The most extensively studies air pollutant since the industrial revolution
⬢ SO2 is a point source pollutant
⬢ S is present in combusted materials and released by heat of combustion
⬢ S reacts with O2 in the air to form SO2
- Dispersion Patterns of SO2
-
• From “short stacksâ€
o Graded zones of SO2
o Concentrated to dilute
o Zones called “isoplethsâ€
o Following prevailing winds
• From “tall stacksâ€
o Dispersion over wide area with little contact with the ground
o Long range transport by prevailing winds
o “The solution to pollution is dilutionâ€
- Complete Combustion
-
⬢ At high temperatures
⬢ Fuels are rapidly oxidized to O2 yielding large amounts of heat and light
⬢ Plus products of complete combustion
o CH4 + 2O2 yields CO2 + 2H2O
o (CO2 & H2) are reradiative gases
⬢ It has a Blue flame
- Incomplete Combustion
-
• Much of the carbon in fuels is not converted to CO2
• Some is only partially oxidized to carbon monoxide CO
• Some remains as elemental or organic carbon in particulated emitted as smoke
• Everything we have is inefficient and incomplete
o i.e. : lawn mowers, chainsaws, cars, pretty much everything except clean burning furnaces
• It’s the real cause of our problem
• It has a yellow flame
-
Combustion
PAHs -
⬢ Compounds with two or more aromatic (benzene) tings which are fused together when a pair of carbon atoms is shared between them
⬢ Lower molecular weight compounds (2-3 ring group) are toxic
⬢ Produced at lower temperatures in wood stoves and furnaces
⬢ Higher temperatures in fireplaces destroy PAHs
⬢ Diesel engines also produce PAHs
-
combustion
Trucking Industry and PAHs -
⬢ Very popular in the western part of the country
⬢ Little particles are emitted from the smoke stacks on trucks
o PAHs
⬢ Have begun to put trucks onto trains to reduce this, but trains still have incomplete combustion so you can never really get away from it
-
Combustion
Low Molecular Weight Hydrocarbons -
• Formed during fuel combustion in gasoline and diesel engines
• These “unburned†hydrocarbons are even less oxidized than CO
• Become part of the photochemical oxidant cycle with anthropogenic influence
• Come out of your tail pipe. Don’t go away.
- Nitrogen Compounds
-
⬢ High temperature combustion encourages the formation of NOx (NO + NO2)
o beginning of the cycle that produces ozone
⬢ Photochemical oxidant cycle
⬢ Acidic deposition cycle
-
combustion
stuff to be familiar with -
Volcanoes
• Natural source of
o Sulfur
o Nitrogen
o Ash
o Toxic gases
Chlorine Compounds
• Methyl chloride – wood
• Hydrogen chloride - incineration of plastics (PVC)
Incineration of Plastics
• Incineration of plastics in furnaces results in production of carcinogenic chlorinated compounds
o PCDFs
• Dinenzofurans
o PCDDs
• Poly-chlorinated dibenzodioxins
o Dioxins
• Tetrachlorodibenzo-p-dioxin
Metals
• Found as impurities in fuels and mining ores
• Highest in coal
• Released as trace elements in ash and smoke
• Distributed by wind away from point sources
-
combustion
Fire in the forest -
• Surface fire
o Consumes litter and debris on the ground
o Kills herbaceous plants and woody seedlings
o Scorches the bases of large trees
• Ground fire
o Consumes organic layer under debris
o Combustion is down to the underlying mineral layer
o This prevents seedling regrowth
• Crown fire
o Canopy or “crowns†are consumed by fire
o Requires abundant debris and litter on ground and winds to bring flames to the treetops