Geol 105 Exam 2 Study Guide
Exam 2 will be given on April 4th. This study guide includes topics/answers that are on the checklist the professor gave us March 28th. It will include information from chapters 13-16.
Global water cycle: evaporation (water goes up into atmosphere), precipitation (water goes down in the form of rain), transpiration (loss of water due to plants), surface runoff (as it rains, water moves from high elevation to low elevation), subsurface groundwater flow (movement of water under Earth’s surface)
Drainage basin-aka watershed, an area of land which puts in water to a certain stream or river Drainage divide-boundary between two drainage basins that are next to each other
● Vadose zone-the earth material above the water table, serves as early warning area for potential pollution to groundwater (GW) resources
● Zone of saturation-under vadose zone, infiltrated by water that seeps down from earth’s surface; where true GW flow occurs
*upper surface of zone of saturation=water table=boundary between the 2 zones
Aquifer-earth material capable of supplying GW at a useful rate
Unconfined aquifer-has no confining layer restricting upper surface of zone of saturation Confined aquifer-if confining layer is present
Artesian well-created by water rising up from rocks due to pressure
Recharge zone-any process which adds water to an aquifer (Ex: precipitation) Discharge zone-any process which removes GW from an aquifer (Ex: natural discharge from a spring) Don't forget about the age old question of How does smoking tobacco during pregnancy increase the risk of having a low birthweight infant?
If you want to learn more check out What is biosphere's description in short answer?
Influent stream-above the water table, only flow in response to precipitation Effluent stream-perennial; flow all year
Cone of depression-occurs when water is pumped from a well; can alter the direction of GW movement within an area
Cone of ascension-formed by extensive pumping in coastal areas can cause salt water to rise into wells
Hydraulic conductivity-ability of a material to allow water to move through it Porosity-percentage of void/empty space in sediment or rock
SAND AND GRAVEL have high hydraulic conductivity and can be an aquifer. GW moves fast through sand but slow through clay.
CLAY has low hydraulic conductivity and can be an aquitard.
Probs caused by overdraft of GW: Reduce stream flow, lower lake level, reduce water in wetlands
Probs caused by overuse of surface water: deplete GW resources
Karst topography -surface land with thin bed of limestone underneath
Problems (pollution transportation): If you want to learn more check out What are forward and backward shifting of tax for?
● Water pollution occurs where sinkholes have been used for waste disposal ● Cavern systems prone to collapse, making sinkholes
● Springs aren’t receiving as much GW flow due to mining
3 types of water use:
Offstream-using water that has been removed or diverted from its source Consumptive-type of offstream use; water does not return to the stream or GW resource immediately after use
Instream-water used that is not removed from its source
Water Management: linkages between surface and groundwater must be understood To be considered: alternative water supplies, better protecting, managing (conserving) existing supplies, and controlling population growth If you want to learn more check out What are tetrahedral sigma bonds?
Wetlands and Ecosystems
Wetlands greatly affected by water resources developments (building dams, canals, etc) Effects of water resources developments: loss of land, migrating fish unable to move upstream, foreign sediment being trapped, reducing water storage capacity, river/coastal erosion If you want to learn more check out What is the real exchange rate?
We also discuss several other topics like What is pseudoparticipation?
Pollutant-any substance that is known to be harmful to desirable living organisms Common pollutants:
● BOD indicates (Biochemical Oxygen Demand)- high BOD means lots of decaying organic matter in the water
● Fecal coliform indicates-biological pollution
● Nutrients (N and P)-nitrogen and phosphorous; used in fertilizers, detergents, etc; causes cultural eutrophication
○ Cultural eutrophication-natural process characterized by rapid increase in abundance of plant life, mostly algae
■ The algae block sunlight to plants below, those plants
■ Algae also takes out more oxygen in the water, negatively
impacting other organisms
○ Case history of summer of “dead zone”
■ Shore of Louisiana
■ Low concentration of oxygen in water kills shellfish and crabs ■ Supposedly caused by Mississippi River
● Oil-oil spill in Gulf of Mexico (Deepwater Horizon) was worst oil disaster in US history; marine life, sea birds, other organisms harmed
● Toxic waste
○ Synthetic organic compounds-organic compounds have carbon that is produced naturally or synthetically; many uses (pest control) ○ MTBE-methyl tert-butyl ether; added to gasoline to increase oxygen level and decrease CO2 emissions
○ Heavy metals-include lead, mercury and zinc; dangerous pollutants usually deposited with natural sediment in bottoms of streams, pollutes ecosystems, toxic to animals and humans
● Sediments as pollutants-greatest water pollutant , depletes soil, reduces quality of water, deposits undesirable materials on useful land
Point source pollution-discrete and confined, controlled by onsite treatments or disposal (sources: pipes which empty into streams or rivers from industrial/municipal sites)
Nonpoint source pollution-diffuse and intermittent; difficult to control contains multiple types of pollutants (sources: runoff from streets or fields, agriculture, forestry or mining)
Why care about GW pollution? 50% of Americans depend on GW as primary source of drinking water. Our health can be greatly impacted by the compounds in GW.
GW Pollution: caused by leaks from pipes/storage tanks, accidental spills, intrusion of saltwater, etc
Surface Water Pollution: caused by saltwater intrusion, aquifer pollution due to disposal of wastes on land surface or in the ground
Failure of septic tank sewage disposal system: waste material rises to surface, causing potential health probs, GW resources may become polluted
Reduce effects of water pollution: develop/ refine better ways to evaluate water pollution, cost effective and innovative technology for treatment, develop ways to minimize water pollutants and their effects
Processed materials from minerals account for 5% of US GDP
Resources-elements, compounds, minerals, or rocks concentrated in a form that can be extracted to make a profit
Reserves-portion of a resource that is identified and available to be extracted for profit
Hypothetical resources-undiscovered resources which are assumed to be in known districts
Speculative resources-undiscovered resources that are assumed to be in undiscovered districts or forms
Concentration factor-ratio of its necessary concentration for profitable mining to its average concentration in earth’s crust
Genesis of Mineral Resources:
● Diamond and igneous rock kimberlite-diamond crystals!
● Crystal settling-sets apart new and older crystals
● Hydrothermal deposits (gold, mercury, etc)-common type of ore deposit; come from late stage magmatic processes, mineralizing fluids move through host rock, crystalize as veins or small dikes
● Metamorphic process (high temp., high pressure, recrystallization) ○ Contact metamorphism-caused by heat, pressure, and chemically active fluids of cooling magma interacting with surrounding rock ○ Regional metamorphism-can change mineralogy and texture of preexisting rocks, producing ore deposits
● Evaporite deposits (gypsum, halite, potassium minerals, etc)-variety of compounds, minerals and rocks which have high commercial value ● Placer deposit (gold)-ore formed by deposit of sediments
● Weathering process-concentrates some materials to point at which they can be extracted for a profit
○ Laterite-type of soil created by weathering of some rock forms ○ Bauxite-comes from certain aluminum ores after biological processes take place
Divergent Boundary-metallic ore deposits related to migration of ocean water Midocean ridge-cold water moves down fractures in basaltic rocks at ocean ridges, heated by nearby molten rock
Black smoke-chimney shaped, emit black, mineral charged hot water, metal oxides and sulfide deposits
Convergent Boundary-due to partial melting of seawater-saturated rocks of ocean floor in a subduction zone; mercury and gold deposits
Impact of mineral extraction and processing
On land-aesthetic degradation, increased land used for mining disposal sites, cyanide leaching, open pit mines
Water-surface drainage, runoff from precipitation, leaching of trace elements, water pollution
Air-pollution, smelting, health hazards
Topographic change-mining removes material in some areas and dumps waste in others, environmental degradation
Why is mercury used in gold mining? Gold clings to liquid metal (mercury). How does mercury affect biological environment? Toxic to organisms; health hazards/death.
Recycling mineral resource
Most recycled metals: iron and steel
Why? Market for iron and steel is huge, so large scrap collection/processing industry exists, economic burden if recycling does not happen, significant environmental impacts
R/C ratio R= known reserve C=rate of consumption
Peak oil time is the time when one-half of Earth’s oil has been extracted and used. Fossil Fuels-organic, nonrenewable resources
Oil=number one energy consumption in US
Classification of Oil based on:
Carbon content, caloric (heat) value on combustion, sulfur content
World Distribution of Coal
US has 25% of coal reserves
Environmental Impact of Coal:
● Strip mining on more land
● Ash from coal must be properly disposed
● Environmental effects, like water pollution
● Carbon dioxide emissions
Methane (CH4) is the main composition of natural gas.
Geologic Condition for Oil and Gas Fields:
Source rock-fine grained, organic rich sediment; oil and natural gas originate as Reservoir rock-porous, permeable rocks like sandstone or fractured limestone Cap rock-the barrier which stops or slows down oil or gas from moving upward
Common Traps of Oil:
Coal bed methane-type of well that is shallow and cheaper to drill than typical oil wells
Methane hydrate-white, ice like material made of methane gas surrounded by frozen water
Tight gas-black shale is a tight natural gas; distributed in tight openings throughout black shale, contains high content of natural gas
Environmental Impact of Exploration and Production of Oil and Gas: Building roads, exploratory drilling, supply line (few adverse effects) Drilling wells on land or beneath sea, disposing waste water, transportation of oil
New Energy Resources and their Environmental Impact:
Nuclear Energy-relies on fission, radioactive waste management Solar-low impact; large land necessary
Geothermal-on site noise, gas emissions, scars on the land
Hard Path-”business as usual”; method US is using; ignoring the need to find alternative energy sources
Soft Path-taking steps towards conservation of resources