Science Section 3 - Part 1 Flashcards
What is
Growth Rate
Percentage change of a population; depending on births, death, immigration, and emigration
What is
crude birth/death rate
The number of births/deaths per 1000 people
What are
higher-income countries
Europe, North America, etc.—comprising 1.3 billion people.
What are
lower-income countries
AKA less-developed
Haven’t or still are industralizing—comprises 6.7 billion people
Includes China and India
How has the population difference between more- and less-developed countries changed?
Populations in less-developed countries have continued to grow rapidly (~1.5%), while richer countries’ have almost leveled off (~0.2%)
What is
environmental degradation
Pollution and other disturbances to the environment, human & natural
What contributes to environmental degradation?
The extraction, processing, use, and disposal of human-used resources
What is
environmental impact
The population ✕ Resource use per person ✕ The impact of the resource
How has energy use changed over time?
Energy use has increased at a greater rate than population growth.
What was the population and fossil fuel consumption in 1960?
- 3 billion people
- 3,000 million tons of oil equivalent
What was the population and fossil fuel consumption in 1999?
- 6 billion people
- 7,900 million tons of oil equivalent
What was the population and fossil fuel consumption in 2022?
- 8 billion people
- 11,500 million tons of oil equivalent
How has energy use changed over time?
Energy use has increased at a greater rate than population growth
What is
fertility rate
The average number of children born to each woman through her child-bearing years, in a population
What is
replacement fertility rate
The average number of children per woman required to replace a population (maintain population levels); around 2.1
What is
life expectancy
Years expected to live of an infant born in a given year
How does life expectancy differ between men and women?
Women generally live longer than men, due to lifestyle choices and dangerous workplaces; gap is decreasing as women enter the workforce.
What is
infant mortality
The number of deaths of infants (age<1) per 1000 births
Does the USA 🇺🇸 have the lowest infant mortality?
Canada 🇨🇦, Finland 🇫🇮, Iceland 🇮🇸, Ireland 🇮🇪, Japan 🇯🇵, Sweden 🇸🇪, and France 🇫🇷 have rates 1–2 deaths per thousand lower than the US, which spends more per capital on healthcare.
FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE. FALSE.
How can you measure the level of healthcare of a country?
Life expectancy and infant mortality; NOT crude death rate, because that is a reflection of age (e.g. mexico (5) vs USA (9))
Why does US 🇺🇸 infant mortality differ from comparable countries?
- No Universal Healthcare
- Less generous time off
- Disparity in healthcare for minorities
What is the
%<15/%>65 figure
Percent of the population younger than 15
vs.
Percent of the population older than 65
What is an
age structure diagram
A chart showing a population divided by age groups and gender, representing age distribution.
Brainscapes charges to add images. Google it.
What is a
population pyramid
A pattern appearing in lesser-developed countries, where fertilty rate is high; there are lots of young people, so the age-structure diagram looks like a pyramid.
Older countries get an inverse pyramid. Stable populations are columns.
Google it.
What are the layers of the Earth?
- The dense core
- The mantle (80% of volume)
- The crust on top
What is the distribution of iron in the Earth?
The whole Earth is 35% iron, while only 6% of the lithosphere is iron.
What is the
lithosphere
The first 100km of rock, where the rock cycle occurs and soil gets elements from; includes the crust and outer mantle
What are the elements of the atmosphere?
- Nitrogen (78%)
- Oxygen (21%)
- Argon (0.9%)
- CO₂ (0.036%, trace gas)
What are the
building blocks of life
- Carbon
- Hydrogen
- Oxygen
What are the
macronutrients
>0.1% of dry weight:
* Nitrogen
* Phosphorus
* Potassium
* Calcium
* Sulfur
* Magnesium
What are the
micronutrients
<0.1% of dry weight:
* Manganese
* Iron
* Copper
* Zinc
* Molybdenum
* Chloride
* Boron
What is the
aqueous phase
A chemical form of an element that can dissolve in water (necessary for plants)
What is
soil water
The water in pore spaces between soil particles that faciliate element exchange
What does weathering do?
Physical/chemical breakdown that releases elements from mineral rock
What does erosion do?
Moves elements around via wind/water
How is weathering accomplished?
- Water
- Wind
- Acid Rain
- Other chemicals
- Roots of growing plants
Where are calcium, magnesium and potassium derived from?
Primarily rocks and decomposed vegetation
What rock types do calcium and magnesium occur in high concentrations?
Limestone, dolomitic limestone, and marble
What ecosystems are calcium and magnesium found in?
Those overlying limestone and some other rock type
What elements did the dust storms of the ’20s and ’30s carry?
Calcium and magnesium, carried westerly into the central and eastern states
What caused the dust bowls of the ’20s–’30s?
The topsoil was destroyed by:
* Heat
* Drought
* Wind
* Poor agricultural practices
* Other human land use
What is the gaseous component of sulfur?
Sulfur dioxide, SO₂
What form of sulfur do plants take up?
The sulfate anion, SO²⁻₄; also comprises acid rain
What is a natural atmospheric source of sulfur?
Volcanoes, which release the natural pool of sulfur in rocks and mineral
TRUE OR FALSE
Sulfur deposition is higher than that of nitrogen
TRUE! Although air regulations have decreased it since 1995 in the US 🇺🇸
TRUE OR FALSE
Sulfate does not leach easily from soils and ecosystems
FALSE!
What are the benefits of soil?
- Plants grow in it
- Filters water
- Bacteria, fungi, disgusting insects, other animals live in it; some very important decomposers
- Filter some air/sewage pollution
- Bonus: Food. Be grateful.
What are
soil horizons
Layers of soil distinguished by physical/chemical/biological factors
What is the
O horizon
Specifically the top layer in forests, consists of needles, leaves, woody material, animal bodies, animal droppings.
What is the
A horizon
Usually the top layer, consists of humus (organic material) and mineral soil that has been mixed together, by animals/plants/humans.
What is the
E horizon
Only exists in more acidic soils; chemicals have leached out, and is left light in color. Below the O or A horizon.
What is the
B horizon
Where chemicals accumulate from the O, E, and A horizons, along with elements that weathered in place. Always exists.
What is the
C horizon
Least weathered, always occurs below B horizon. Similiar to the parent material (original soil material). Contains roots/microbes in humid regions; otherwise they extend only into the B horizon.
What is
humus
Organic material in the soil from plant and animal matter
What are
state variables (soil)
The factors that cause soil to progress and determine its nature:
* Parent material
* Climate
* Topography
* Organisms
* Time
What is
bedrock
The solid rock underlying the soil. Usually synonymous with parent material; not when e.g. glaciers have spread a layer of sediment on top of the bedrock, separating the parent material.
What is
parent material
The original rocky material from which the soil is derived; a state variable that determines the nature of the soil.
How does climate affect soil formation?
A state variable; the sum of weather-related variables over time:
* Temperature increases weathering and soil formation
* Freeze-thaw cycle increases surface area for weathering
* Precipitation (also causes weathering) and temperature increases leaching
* Also influences the type of vegetation, and the rate of decomposition
How does topography affect soil formation?
The surface configuration of a landscape; a state variable:
* Soils on steep slopes face erosion and landslides
* Landslides are hazardous to soil, ecosystems, and people
* Horizontal soils & those at the bottom of mountains tend to accumulate material
* Windward sides of mountains have more precipitation than the leeward sides
“Despite these well-known dangers, people continue
to build on such soils—often quite expensive structures—and seem surprised when they are destroyed.”
What are
detrivores
Organisms that consume dead plant and animal matter
What organisms account for 80–90% of biological activity in soils?
These eat plants (dead&alive), + animal waste (detritus); majority are detrivores. Bacteria liberate nitrogen & sulfur from the soil for plants to use.
* Fungi
* Bacteria/Archaea
* Protozoa (single-celled organisms, e.g. algae)
(detrivores: consume dead plants and animals)
How many more detrivores than herbivores are there in the first 15cm of soil?
There are 10 times as many detrivores than herbivores.
(detrivores: consume dead plants and animals)
In the temperate zone, what is the most important macrofauna?
(Macrofauna: Large (relatively speaking) animals)
Earthworms!
They can ingest 2–30 times their weight in soil every day! Also they:
* Extrete nutrient-rich organic matter, which improves soil quality
* Aerate the soil
* Improve water drainage
* Mix upper and lower layers of soil
* Are sensitive to acidic soil; do best in neutral pH
How does soil change over time?
Time spent unfrozen influences soil development:
* New soil has very little separation into different horizons
* Soils develop horizons and characteristics over time
* Grassland soils in e.g. the Great Plains have very thick and nutritious and delicious A and B horizons that developed over hundreds of thousands of years
What is
soil degradation
The loss of some or all of a soil’s ability to support plants
What is
topsoil
Soil of the A or O horizons; can take centuries to replenish
What are the causes of soil degradation
- Erosion which carries away disturbed (by e.g. plowing) topsoil by water or wind
- Compaction from machines
- Nutrient depletion from intensive use
- Irrigation
- Chemical damage from e.g. pesticides
How has soil degradation affected the world today?
Worldwide, there has been a 17% reduction in food production, most prevalent in Africa and Europe
How is climate change affecting soil degradation?
- Slightly warmer temperatures may increase decomposition
- But dryer soils may slow decomposition
TRUE OR FALSE
Soil in areas of extreme temperature/precipitation recover from soil degradation slowly.
TRUE!
How much water is fresh water?
3%, most of which is in ice—only 1% of all water is potentially usable by humans and terrestrial organisms
How much of Earth’s water is in lakes, rivers, reservoirs, the atmosphere, and within organisms?
- only 0.009% in lakes, rivers, and reservoirs
- perhaps 0.001% in the atmosphere
- less than 0.0001% within organisms
What is an
aquifer
Permeable layers of rock and sediment that hold water
What is an
unconfined aquifer
An aquifer of porous rock (such as sandstone or other consolidated sediments) covered simply by soil.
What is the
water table
The top of the area within an aquifer saturated with water
What is an
aquiclude
An impermeable layer of clay that stops groundwater flowing from an aquifer; confines the aquifer
What is a
confined aquifer
An aquifer confined from above and below by an aquiclude
What is an
artesian well
A well drilled into a confined aquifer, which can have water flow without needing a pump
What is one type of surface water that is fed by groundwater?
A spring; a small stream that “springs” out of an aquifer during wet seasons.
What are the problems introduced by constructing an aqueduct in a desert/grassland?
- Vegetation is disrupted
- Soils are disturbed
- Animal habitats are altered or destroyed
How much water is lost due to leakage from old or damaged pipes in Jordan and the Occupied Territories of Israel?
As much as 55%
Countries from the Middle East and North Africa are responsible for how much of the world’s fresh water produced through desalination?
More than 50%
How is water desalinated through distillation, and what is its downside?
Water is evaporated, leaving behind salts; the steam is then condensed, producing pure water. This is, however, a highly energy intensive process.
How is water desalinated through reverse osmosis, and what are it’s benefit and downside?
Water is forced through a membrane; the water passing through is very pure, and that left behind is highly salty brine. This is cheaper and more efficient than distillation, but brine released into the ocean can impact local ecosystems.
In 2023, how much water was used in the US 🇺🇸?
408 billion gallons per day, or 1,300 gallons per person per day
Lower water use in most other countries
This includes domestic use, commercial and municipal use, irrigation for agriculture, and cooling for electrical power plants.
How much of worldwide food production benefits from irrigation?=-
40%
How much water does it take to produce one ton of grain?
1,000 tons
(250,000 gallons)
What is
conventional irrigation
Water runs through a ditch alongside crops; 60% efficient
What is
drip irrigation
A tube buried in the ground releases water slowly; 95% efficient, but more expensive.
What is the effect of prolonged droughts on soil?
Can dessicate the soil to such an extent that the topsoil blows away; Land can’t be farmed for decades; Subject to erosion from flooding, as it can no longer absorb much water
des·ic·cate
/ˈdesəˌkāt/
verb
remove the moisture from (something); cause to become completely dry.
What happens to an aquifer during a drought?
During droughts, aquifers usually contain some water. If an aquifer is overpumped though, it can be depleted, which may result in wells going dry.
What happens when a well next to a coastline is overpumped?
Nearby saltwater will be drawn into the aquifer, saltifying the water in a process known as saltwater intrusion
What are two recent major floodings?
- West Bengal, India (2000) — destroyed >800k homes, killed hundreds of people
- Worldwide flooding in 2023, driven by increasingly intense storms
What are the environmental benefits of floods, hurricanes, and torrential rains?
When water overflows a river’s banks, nutrient-rich sediment improves the soil quality
How many people do not have access to safe drinking water?
1–2 billion people, most in the developing world
What are
point sources
A distinct, confined source of pollution
(such as a sewage pipe, or factory)
What are
non-point sources
A diffuse (spread out) area from which pollution originates
(such as a parking lot, or farm)
How can pathogens contaminate water?
- Malfunctioning sewage treatment/septic systems (point)
- Wildlife (non-point)
What pathogens are common in the US 🇺🇸?
- Hepatitis A, originating in unclean restaurants
- The bacterium Cryptosporidium, which has caused outbreaks of gastrointestinal illness
- The parasite Giardia, which has been transmitted into mountain waters by hikers
What is
oxygen-demanding waste
Organic material in water (like leaves and twigs) that attract decomposing bacteria which deplete the oyxgen levels of the body of water
What is
biochemical oxygen demand (BOD)
A measure of oxygen-demanding waste—the amount of oyxgen used over (usually) 5 days at (usually) 20℃ in a certain amount of water. Lower numbers mean more pristine water.
Sewage may have 200 mg of BOD per liter of water; natural water may have 5–20.
How do different amounts of dissolved oxygen (in ppm, parts per million) affect ecosystems?
When dissolved oyxgen is high, BOD is low—and vice versa.
8–9ppm is high quality and ideal for aquatic ecosystems. ~4ppm is polluted, where fish have trouble functioning.
What is
eutrophication
The excessive growth of algae due to an oversupply of nutrients; when the algae dies, BOD increases sharply and the fish population suffocates.
How does nitrogen and phosphorus enter bodies of water?
Nitrogen: farm runoff, sewage treatment, acid precipation
Phosphorus: naturally occuring rocks and minerals, fertilizer, and in the past, detergents.
What metals are among the most toxic water pollutants?
- lead
- copper
- arsenic
- mercury
What is the US 🇺🇸’s largest source of mercury emissions?
Coal- and oil-fired power plants that deposit it on land and in waterways
How does inorganic mercury (Hg) become methylmercury?
In wet, anaerobic environments such as wetlands, aquatic sediment, and temporarily saturated soils, bacteria convert mercury to methylmercury.
an·aer·o·bic
/ˌanəˈrōbik/
adjective
relating to, involving, or requiring an absence of free oxygen.
“anaerobic bacteria”
How is methylmercury toxic to humans?
Damages the central nervous system, including coordination and the senses of touch, taste and sight, especially in embryos and small children
What are
persistent organic pollutants (POP)
Toxic, industrial chemicals that persist for decades or longer, accumulating in organisms throughout food webs.
What are
PCBs (polychlorinated biphenyls)
Highly toxic and carcinogenic, they were used in plastics and insulation until 1979; they are still present today.
What was the cause of PCB pollution into the Hudson River?
A General Electric plant.
What was done to clean up the Hudson River of PCBs?
The EPA ruled in 2002 that General Electric must pay for the dredging and removal of PCB-contaminated sediment from the river bed. Under a 2006 agreement, dredging began in 2009 and finished in 2015; it is still monitors for developments.
What are sources of sediment that pollute water?
- Housing & shopping development
- Agriculture
- Dam construction (sediment accumulates in unmoving water; runs downstream when mobile again)
How does sediment water pollution affect ecosystems?
Sediment can clog fish gills and otherwise impede oxygen intake, particularly in bottom feeders (oysters, clams). Also stops sunlight, decreasing primary productivity.
What causes thermal pollution in water?
- When water moves slower
- When water receives more sunlight
- When water enters a shallower waterway
- When used for cooling in industrial areas and power plants
(all humans causes)
How does thermal pollution in water affect ecosystems?
- reduces the possible amount of dissolved oxygen
- Increases the respiration of organisms, further reducing dissolved oxygen
- Stresses organisms, making them more susceptible to disease
- May also affect reproduction
What is the most notorious recent oil spill?
The Deepwater Horizon spill of 2010 in the Gulf of Mexico, which had 210 million gallons of oil cover ocean and coastlines, deeply impacting local ecosystems; cleanup continues to this day
What are the cleanup methods of the Deepwater Horizon oil spill?
- Floating booms to prevent oil from spreading
- Skimming oil off the water’s surface
- Chemical dispersants that break down oil until it’s small enough to be destroyed by sunlight and bacteria
What are the sizes of microplastics and nanoplastics?
Smaller than 5mm and 0.0001mm respectively
What is
gray water
Wastewater that is not from toilets, like from sinks or showers; can be used without treatment for e.g. watering lawns
Properties of sewage?
- High BOD
- Pathogens
- High levels of nitrates and phosphates
How is sewage decomposed?
- Bacteria break down organic matter into CO₂ and inorganic compounds like nitrates and phosphates
- Dissolved oxygen levels are reduced in the water
- Eventually, BOD goes down, and oxygen levels recover
Sewage treatment plants replicate this process (usually quicker)
What is
primary treatment
Removal of 40–50% of solid waste material from sewage; becomes sludge
What is
sludge
Solid material from primary treatment that has settled and dried
What is
secondary treatment
Acceleration of the natural breakdown of organic matter in sewage; by the end, roughly 85–90% of original pollutants have been removed. After disinfection, the water can be released into a body of water to join the water cycle.
What is the history of water quality in the US?
🇺🇸?
- 40–50 years ago, harbors and waterways were badly polluted
- the Clean Water Act (passed 1972 and amended since then)
- the Safe Drinking Water Act of 1986
- the Water Resources Development Acts (1986–92)
What did the Clean Water Act (1972) accomplish?
- establishment of Water Quality Standards that limit the concentration of specific pollutants in major bodies of water
- to achieve these Standards, established a Total Maximum Daily Loads for each pollutant—the maximum amount of each that can be discharged from any point or non-point source
What did the Safe Water Drinking Act (1986) establish?
Established maximum containment levels (MCL) for 77 different elements or substances that is the enforceable amount that must not be exceeded.
enforceable, not harmful. reflects the feasibility and cost of reaching ‘good’ levels
