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Env Geo Final

HElp me dear lord baby jesus

The human population on earth can be roughly modeled using exponential growth rate (k) hasn't been constant over the last 300 years. When did we see a substantial increase in k? 1950, during the baby boom, duh
We've created a cropland & pasture biome that covers what % of the earth's surface? 40%
Today atmospheric CO2 is close to 390 ppmv
Which soil forming factor has the most control over US fertile soils from coast to coast? Climate
Civilizations collapse every ~1000 years because ag causes topsoil to erode at a rate of...? 6m/my
During the 20th century, how many people died from flooding? 10,000 (same number of digits as letters in the word flood)
Compared to the natural rate of 180 mt/yr human-induced N fixation is estimated to be...? also 180 because we've doubled it
What % of US rivers are dammed 98%
The # of flood deaths has done what since early 1900s? remained the same, not gotten better with technology
If you were to walk in the channel of a typical mid-atlantic stream 400 years ago, your feet would mostly be in...? an organic-rich silt loam
Channel erosion is commonly responsible for what % of total stream sediment load? 60-80%
In a northern deciduous forest, in what month does evapotranspiration have the strongest control on reducing stream discharge? August because summer, everything is the alive-est
What is the specific design goal of a stormwater retention pond in James County, VA? to delay the peak inflow to outflow stormflow centroid of the 1-year event by 24 hours (the complicated one)
Erosion rates from ag field plowing now, compared to native methods, creates how much larger rates of soil production? 10 to 100 times
By what factor has the 30-year stormflow increased? do e^(wherever the line ends up) for both lines. Divide the bigger product by the smaller.
Global sea level has been rising at what rate throughout the last 130 years? 1 inch (2.5 cm) per decade
What is responsible for the LARGEST AMOUNT of sea level rise in the last century? thermal expansion of the oceans
On average, what percentage of N deposition runs off into surface waters in any given year? 20%
When did human impacts first show up in the sedimentary record in the bay? 1775 (american revolution times)
What sector contributes the highest N and P loads to the Chesapeake Bay? Agriculture
Over the last 20 years, how has the size of the Chesapeake Bay dead zone changed? it has remained about the same size
What is true about how N & P additions to ecosystems increase productivity? Adding N&P to any ecosystem usually causes significantly more productivity than either nutrient alone
What is the best indicator of freshwater anoxia? pyrite
Radioactive Cesium 137 can be used to trace soil erosion since...? the 60s.
Driscoll M - in the US, what is the largest source of Hg emissions to the atmosphere? coal-fired electric plants
Driscoll M - in the US, have total Hg emissions increased, decreased, or remained constant since 1990? they have decreased
Driscoll M - what specific environment (or habitat) is most sensitive to mercury deposition, with respect to having the most severe accumulation of mercury in biota? Forested areas with unproductive surface water
Chen M - List 5 specific variables they used to determine mercury content of fish in the northeastern US. pH, sulfides, dissolved organic carbon, acid neutralizing capacity, fish type.
Gasses in the atmosphere & residence times *N2, *O2 (long residence time), *Ar, CO2 (long 10 yr residence time), Ne, He, Kr, H2, CH4, SO2 (short residence time), NOx (long 100 yr residence time), H2O (short residence time)
Aerosols suspended particles or liquid droplets • ~20 day residence time in the troposphere (close to the residence time of water) • ice • dust (soil, salts) • liquid droplets
Heavy Metal Ores: Sulfides -earth sequesters the toxic metal Pb in Galena (PbS) -other metals that bind to sulfide – mercury, gold, copper, zinc, silver -he who smelted it dealted it (S)
Wet and Dry mechanisms of deposition -wet • rain • snow -dry • dustfall • direct uptake (by plants) • cloud water impaction (commonly forms when H2O gas reacts with a particle in the atmosphere and goes to H2O liquid. Can have a pH of 3 or 4. Bad for high elevation ecosystems)
What is the range of pH across US ~6 to ~4.7
What is the geographic distribution of acid rain in the US? most on east coast (east of MS river). Major acid in industrial areas. Most in ohio, PA, WV. Less in agricultural areas.
By what factor does [H+] vary across US? A factor of 20
Dry deposition & importance of vegetation -vegetation traps bad stuff (condenses on it) -it breathes it in through stomata -they trap a lot of mercury -how long do contaminates stay in soil? Mercury – long time. N – 10 to 30 yrs. Definitely decades.
Elevation & atmospheric deposition -huge change in deposition along a landform. -40 to about 140. Cloud water makes the difference. -cloud base is a sharp feature responsible for a threshold in forest and soil composition
Sulfate ion wet deposition -really bad in northeast -sulfur is a stronger acid (than nitric acid) -S tends to dissolve in water faster -mountains and more rain
Wind patterns matter for S deposition -takes contaminated air to the northeast -coal plants largely to the south of contaminated areas
Indicators of atmospheric contaminants -dead trees in high elevation areas (NE of coal plants) -dead lakes (loons, fish)
Acid deposition effects (part 1) -you start to lose the soil nutrient saturation -soil particles tend to have a negative charge (Al3+ subs for Si4+) -base cations (nutrients) are attracted to it
Acid deposition effects (part 2) -so they stick to negatively charged particles. We like this. Plants can grab the nutrients when they need to (by exuding H+) and the nutrients will go up the root. This is ion exchange.
Acid deposition effects (part 3) -so acidified soils will have H+ everywhere instead of nutrients (low BS soil) -Ca deficiency in trees made them very intolerant to cold. -Al goes up in low pH water. Thats what actually kills the fish (their gills get filled with it and the suffocate)
Shenandoah NP -southern, lower (high 4s) • siliclastic rocks (meta-ss) • no pH buffering capacity • doesn’t dissolve easily -northern, higher (8) • basaltic rocks (7-8) • granites (6.5-7) • chemical weathering reaction buffers acid rain (minerals dissolve)
Sulfur levels -has actually decreased because of successful cap & trade -pH of water is starting to rise
Funny things about mercury -liquid at room temp -coal has it bc Hg associates itself with organic matter naturally -things that hurt you are more like Methyl-Mercury. Billions of x more toxic than anything else. Liquid Hg doesn’t pass through your skin or stay in your body.
Hg, when heated, becomes one of 3 species • Elemental Hg (uncharged mercury gas, not particularly reactive. Dry deposition) • Reactive gaseous Hg (Mercury chloride or bromide, dissolves quickly in water) • Particulate Hg (soot containing some of the mercury, wet deposition)
Coal vs Nuclear -A good amount of electricity is from nuclear -We have 200-300 years of coal left. -22% of electricity comes from nuclear -35 g of U235 (shot glass), has the energy potential of 100 tons of coal. A factor of ~3M more -we have 1000 yrs of coal
Arguments for Nuclear -A LOT LESS greenhouse gasses -Factor of 50 lower -energy and fatality – deaths per trillion kilowatt hour -you can’t even see it, less than 100. Whereas coal is at 200000. -no acid rain associated
Nuclear fission -U235 is heavy, wants to separate -bombard it with neutron, it splits -22% of US energy, 75% of france’s -can propel itself, they have things to dip in, absorb extra neutrons. Without them it could go runaway and meltdown -but has radioactive waste
Issues associated with it -0.1% of rock with Uranium is actually Uranium -what do you do with the rest? Lot of waste associated with mining -you have to do something with the fuel rods bc they’re radioactive -safe/efficient operation of power plants
Deposition -hydrothermal deposit -hot water goes somewhere in crust, dissolved metals re-precipitate when they cool -water-rich magma transport, water infiltrates fractures, metals precipitate -some in valley & ridge from Mesozoic basins, crust thins, rifting
Do we mine in VA? -found in 70s, but then 2 huge disasters in US -coles hill region has some on surface, most below ground -going down = sands, then ore rock (granites and gneisses) around 215 ft down -120 million lbs -we import a lot of our U, political implications
Geological background for VA U mining -rifting ~220 Ma -uranium ore below surface ~1200 ft -it’s an economic deposit How do we do the mining? -turn it into cake
Problems -every 1000 lbs generates 999 lbs of waste -altering environment of rocks at depth, where do you put the water? You oxygenate the system, maybe move U around naturally -largest US disaster – 1979 church rock hill then 3 mile island. Chernobyl worst ever
thermonuclear explosion won’t do a mushroom cloud but... o Instant damage & later cancer/failure of kidneys/liver o U dust has alpha particles o decays really slowly • Human U death unpresc. = 1g • decays to all kinds of radioactive daughters • tailings pile has dust, gas, gamma radiation, mass wasting
Nuclear fuel cycle part 1 -the fission happens in the rods which are in cylinders which are in boxes which are in water which create steam -they are full of radioactive isotopes and bad stuff (lethally radioactive for hundreds of thousands of years)
Nuclear fuel cycle part 2 -150 ish nuclear reactors -waste is either on site or close to it.
Wish list for nuclear waste storage (part 1) • low population density • low elevation (less likely to erode) • tectonically quiet • well above the water table (desert) • somewhere without extreme weather (tornados, hurricanes)
Wish list for nuclear waste storage (part 2) • dry, no flooding • closed basin (not in ocean if it ever washed away) • not near something culturally or ecologically valuable • cold might be better than warm • somewhere safe (not near a border) • in/near rocks that aren’t easily eroded
Yucca - the good o dry (desert) o remote o internal drainage basin o land has already been nuked (since 1950s) o on air force base – easy to secure o low water table o rock is tuff – welded ash and volcanic rock (not soluble)
Yucca - the bad o in basin & range province (tectonically active) o most of the nuclear waste is far away, you have to transport o tuff has water in it. Water vapor is a major constituent of volcanic eruption o tuff is highly fractured, water can travel down
Yucca - the ugly o heat (no way to test that time scale) o climate change o transport o how do you communicate to the next civilization what’s in there?
SAPROLITE chemically weathered rock
Midterm -MS chart question • nothing to do with diatoms • N addition not killing diatoms (diatoms can’t keep up with it because they are limited by silica. Something else moves in to consume that N – algae.)
Global change -over long timescales, we separate climate into “Hot House” or “Ice Age” • 4 major ice ages in the last billion years • several hot houses, mostly during Mesozoic where volcanism was happening
-We are currently in an Ice Age, despite a very recent warming trend -How do we know this? -Sedimentary record (last 100 My) - Ice Evaporation <3s O16. Condens/precip <3s O18. Cloud water becomes more depleted in H2O18 as it moves poleward. Snow & ice are depleted in O18 relative O16. Ice enriched in O16 in glacials. Calcite in glacials are O18 rich. Ice melt = dumping O16 in ocean
-We are currently in an Ice Age, despite a very recent warming trend -How do we know this? -Sedimentary record (Last 100 My) - Ocean sediment o Ocean sediment, dead foraminifera (plankton with calcite shells). Calcite traps ocean chemistry in it. They trap oxygen isotope composition of ocean (H2O 16, H2O 18, etc). Calcite is CaCO3, the O in that reflects the O isotope.
-We are currently in an Ice Age, despite a very recent warming trend -How do we know this? • Isotopes (last 70 My) o Pos # means a lot, - means less. Light until ~50Ma, started to get lighter. ~10 Ma, ocean got heavier. o Last ~2.5 My, = cycles of glacial-interglacial (every 100 Ky) o Ice records give annual scale resolution. Deterium is heavy H. Na, dust, etc.
GHGs and temp change -something causes the temp change, GHGs respond -solids have order, gasses don't -small temp change ~3-5 C -decomp -> to entropy (disorder) and it’s a positive feedback loop -there’s a lag. Greenhouse gasses lag temperature by a few thousand years
Carbon cycling -60 in, 60 out, from atm. 90 in, 90 out in ocean. -stable bounds controlled by terrestrial cycle. -humans putting 6.5 into the atm pool, volcanoes put in 0.05 -400 ppm now (larger that the last My), and projections put us at more than the last 15 My
Methane -molecule for molecule, can do much more warming than CO2 -largely comes from wetlands (anoxic decomposition product) -with glaciation, there’s less decomposition in wetlands
Last 130 years (1880-2013) -relative change on global land-ocean temperature index -global change is something like 1.1 degrees C, which is small change compared to a change between glacials and interglacials -temperature is not a simple climb like CO2 is
what year was the hottest on record (1880-2013)? • Tie between 2005 an 2010
what were the 5 hottest years on record (1880-2013)? • 2010/2005, 2007, 1998, 2002, 2003
beginning in which year do temperatures appear to climb at a faster and systematic (not random) pace? • 1977 (no more negative)
Clean Air Act and Temperature -industry post-WW2, high levels of particulate emissions due to smokestacks. These regulated greenhouse gasses, blocked sunlight. -right after flatline period is clean air act. Then it goes up because particles aren’t there anymore to negate GHGs
Levels of scientific understanding -we have a good scientific understanding of greenhouse gasses, medium understanding of aerosols and clouds, and very low understanding of albedo and solar.
Fertilization theory -idea that more CO2 is creating more plant tissue and that’s the missing sink -FACE project – testing the theory (blasting CO2 at plants)
How much we know (about GCC) -where will C go in the future? Nobody knows. -as far as GHGs go, carbon dioxide, then methane, then N2O, then halocarbons -then with aerosols & clouds we don’t really know
Increase in warming since 1900 - ~1.1ish degrees C globally -not uniform, varies with lat -most warming in N lats • + feedback loops w/ ice caps ^ albedo = Less reflection. • Ice holds in heat, warm air comes up out of the ocean and warms the air -averages mask local effects
What are 2 ways humans have increased N fixation? Burning fossil fuels, Agriculture (N-rich fertilizer)
List three specific environmental effects of atmospheric N species Nitrous oxide - GHG. Nitric oxide - smog. Nitric acid - acidifies water
What are the 3 major carbon pools? Biosphere, Atmosphere, Hydrosphere
What are 2 primary mechanisms by which humans have impacted the global carbon cycle? Burning of fossil fuels, burning of plants
How have SO2 and NOx emissions changed since 1990? Atmospheric SO4 declined because of clean air act. NOx has remained relatively constant.
Which organisms are harmed most by acid deposition? Trees (red spruce, sugar maple), Fish (in acidic lakes/streams, esp. trout)
Created by: haleyBUGoxox