Environmental Science #2

Acid Rain

• used to be much much worse - cap and trade has helped get rid of acid rain

The clean air act of 1970

A law in the United States that established two important policy strategies: air quality standards AND regulations of the source of pollutants.

energy Policy and Conservation act of 1975

Dept of transportation sets minimum miles per gallon standards for cars and vehicles considered light trucks. these standards are known as corporate average fuel economy (CAFE) standards.

Tsunami in Japan 2011

9.0 earthquake off the coast of Japan sent a series of giant waves crashing onto shore and killing thousands, destroying towns and releasing radioactive material from Fukushima nuclear power plant.

Earth’s core

• only began to be understood in the last 60 years - 1961 “project mohole” which drilled 600 feet into the ocean floor

• from 1970 to 1994, the Soviet Union continued “Kola superdeep borehole” 10,000 feet deeper than Mt Everest but was still just within earth’s outer most layer.

Earth’s layers

• hard boiled egg analogy

• Crust (least dense), Mantle (denser), Core (most dense and made of mostly iron and nickel metals; solid inner core surrounded by a liquid outside)

• as earth rotates, the liquid outer core generates a magnetic field, which manipulates the needle of a compass)

Magnetosphere

• an area of space around the earth that shields the planet from highly charged sun rays

Plate tectonics 

• German meteorologist Alred Wegener proposed in 1915 that continents slowly wandered the globe. died in 1930 - they admitted he was right in 1960.

• In 1960, oceanographer Harry Hess discovered the seafloor was gradually spreading, which led to the concept of plate tectonics that was becoming excepted by 1970.

• now it is accepted that tectonic plates are sections of Earth’s crust that rise on top of denser material below, with interactions among these plates shaping Earth’s surface.

• The boarders between tectonic plates are characterized by fractures called faults and the movement if bodies of rock along these faults produce earthquakes.

• Tectonic plates can move at average rates if up to 6 inches per year, with such movements along California’s San andreas fault resulting in the 1906 San Francisco earthquake and others.

demographers and TFR

• Social scientists who study the characteristics and consequences of human population growth.

• examine both current and historical trends

• Use TFR (total fertility rate) to understand changes in population growth over time.

• Replacement fertility is a TFR of 2.1

The Crude Death Rate

• total number of deaths per year per 1,000 people.

• dropped significantly in recent years from about 25 to 7.5.

Demographic and mortality transitions

• Demographic: a decrease in birth AND death rates in a population linked to better overall improvements in basic human living conditions.

• mortality: access to medical care, food, and clean water increase and therefore death rates decrease.

The Demographic Window

• Happens when there is a fertility transition, meaning, younger generations have less children and have them at an older age: therefore, the majority of the population is working class and dependents are relatively low.

• This can lead to a stability transition when birth and death rates are low and the population either does not change or declines if death rates exceed birth rates.

• If this does not happen it can lead to a youth bulge which is often associated with higher crime and civil unrest as there is a huge population of unemployed young people.

Cairo Consensus

• a conference held in 1994 with 184 national governments participating decided that in order to meet demographic and development goals, men and women would need to have equal rights.

I=PAT

Environmental Impact = human Population, Affluence, and Technology

Alfred Wegner

• father of the continental drift theory (1915)

• Died in 1930

• 1960 scientists discovered plate tectonics and realized he was right!

Different types of tectonic plates

• convergent plate boundaries form when plates collide, resulting in a high-standing pile of rock that can form mountains.

• divergent plate boundaries form when plates spread apart from each other and form expanding areas, such as rifts on land or spreading sea floors.

• transform plate boundaries move sideways relative to each other.

The rock cycle

• The geologic process by which Earth recycles and renews its surface

• During a 2018 volcanic eruption in Hawaii, lava spewed from a volcano, and flowed down to the ocean where, once it cooled, it hardened as the island became a little bigger.

The dust bowl

• took place during the 1930s after a lot of plow-based agriculture; magnified dorught conditions.

Sediment

• is made up of eroded material that gets transported and accumulated elsewhere is called sediment.

• after layers build up it becomes sedimentary rock.

Minerals

• are natural solids from Earth’s crust that form rocks that provide key materials for many products, such as electronics, cell phones, and solar panels.

• most of earth’s rare earth metals come from mines in China and are not evenly distributed around the globe.

• very very destructive to mine/smelt/separate.

• Baotou is one of the leading producers of rare earth metals and they have a lot of toxic waste issues because of it.

Watershed

an area of land that drains to a particular point along a river or stream.

flood planes

low lying areas that flood frequently when rivers overflow their banks, slow the flow of a river and allow sediment to deposit.

A delta

• at the mouth of the Mississippi river is a landform created where the river deposits sediment load as it flows to the ocean.

A glacier

a mass of ice that flows over land surfaces and lasts all year.

Overland flow

can occur during a rainstorm when soil is saturated or when rain falls too fast for the soil to absorb the water. Overland flow can also occur because of paved surfaces that are impervious, which means water cannot pass through them; the result is runoff.

Embedded water

accounts for “costs” such as the water used to raise the pig or potato or the barely for beer as well as water used for activities such as bottling or processing.

A reservoir

• any place where water spends time

• together, all of earth’s reservoirs create the hydrosphere (a closed system where are recycled over and over from one reservoir to another)

Residence time

• the amount of time a molecule spends in a particular reservoir

• water molecules average about 10 days in the air while averaging hundreds of years in aquifers.

Aquifers

• when water sinks through the ground and reaches a place where it cannot sink anymore (i.e. bedrock) it collects and forms aquifers.

Evapotranspiration

The release of water vapor from Earth’s land and water surfaces along with transpiration.

Surface water

• Rivers, lakes, the ocean, etc.

• ground water plays a role in providing cooler and fresher water to these systems.

Lentic Ecosystems

• lake and pond ecosystems with relatively still water.

• Littoral zone (shallow water, greatest biological diversity) → pelagic zone is made up of the…photic zone (has enough light penetration to support photosynthesizing organisms) → aphotic zone (deprived of light)

Lotic Ecosystems

• river/moving water ecosystem

• have a large range because of the range in water speed.

Wetlands

• places where the ground is seasonally or permanently flooded with water.

• usually form along flooded banks of rivers and streams during times of peak flow and along the coasts of large lakes when wind causes lake waves to flood the area.

Estuaries

• Wetlands where fresh water meets salt water.

• among the most biologically rich areas on Earth due to abundant light and nutrient rich sediment delivered by the freshwater system.

Ground water

• considered a renewable resource but its recharge time is around 10,000 years meaning it lags behind human usage

• some aquifers are considered nonrenewable - when water is taken from these it is called water mining.

List a few disruptions to surface water systems

• impervious surfaces - divert water to storm drains instead of soil surfaces. They increase flows that erode stream banks, elevate peak flows, and disrupt fish eggs from stream beds.

• man-made canals - contribute to loss of wetlands by preventing seasonal flooding and lowering the water table.

• dams - can interrupt fish migration and cause a loss of water as the trapped water is exposed to the hot sun.

Sources of water pollution (2 main categories)

• Point sources - discharge a contaminant from a clearly identifiable source (pipe, well, channel, etc.)

• Non-point sources - discharge pollutants in a broader more diffuse way. (agricultural or residential activity that enter water through runoff or airborne pollutants from vehicles)

Eutrophication

nutrients in the water increase and accumulate because of agricultural contamination → the buildup stimulates algae growth and blooms of aquatic plants. → the dying plants and organisms use oxygen as they decompose → this depletes the amount of oxygen in the water.

droughts

a prolonged period of low precipitation and high evaporation.

Water conservation strategies

• Water recycling - Typically takes residential water, treats it, and re-uses it for agriculture, industry, or landscape irrigation.

• desalination - removing the salt from seawater - takes A LOT of energy to do.

In the U.S., the federal government regulates water quality primarily by…

• the Safe Drinking Water Act - The EPA identifies contaminants and sets maximum allowable levels for each in the water we drink based on analysis of health risks.

• the Clean Water Act - focusses on stopping pollution in surface water. This law makes it illegal to discharge pollutants from point sources into water without a permit. The EPA sets allowable pollutant levels for each industry or other category of way=ter polluter, these rules are typically administered by state governments.

The cryosphere

all the places on earth where water is frozen.

albedo

sea ice reflects the sun which cools the ocean water below it, so a reduction in sea ice causes the ocean to warm.

Pressure and gas

• The force exerted on or acting against something.

• balloons are firm because of the many gas molecules bouncing around inside.

• all gasses move from places of high pressure to places of low pressure.

How is earth’s atmosphere structured?

• Troposphere (5-10 mi.) - lowest area of the atmosphere where whether occurs. It is very dynamic and holds most of the Earth’s water vapor. Temperatures range from what we are used to -76F (specifically, this temp. is consistent in an area called the tropopause which is located at the top of the troposphere.

• Stratosphere (30 mi.) - holds little water vapor and is relatively calm. This section holds a lot of ozone (o3). 

• Mesosphere - Earth’s coldest temperatures occur here (-148F). Meteors usually burn up here because of the intense amount of friction.

• Thermosphere - upper-most layer of the atmosphere and is slightly warmer because of increased solar and cosmic radiation.

Relative humidity

• compared to the maximum amount of water vapor the air can hold (being 100%)

Barometric Pressure

• a measure of the pressure exerted by Earth’s atmosphere at any given point.

• measured using a barometer.

High Pressure Systems

• tend to be associated with clear and dry conditions.

• contains cooling air that becomes dense and heavier and sinks to form areas of high pressure.

• cold air masses

Low pressure system

• often indicates cloudiness and a higher chance of precipitation.

• When an air mass warms and its molecules expand to fill a greater air volume, it rises as it becomes less dense.

• warm air masses

Fronts (warm and cold)

• form at the boundaries between high pressure and low-pressure systems.

Equatorial low-pressure belt and subtropical high-pressure belt

• Low: The sun’s rays strike the earth more directly in areas closest to the equator, this results in more rapid evaporation and precipitation.

• High: As the air from these low-pressure systems move closer to the troposphere and get colder, moving outward from the equator then descend and cause rising atmospheric pressure. (30 north and 30 south of the equator).

• Once this air reaches earth’s surface, it circles back to the equator where it warms and rises again. These looping weather patterns form a circulation system between the equator and 30 N and 30 N. These are known as Hadley Cells

Ferrel Cell

an air circulation pattern between latitudes 30 N and 60 N and 30 S and 60 S.

Jet Stream

A prevailing wind pattern near the top of the troposphere.

Particulate Matter (PM)

• particulate matter can be composed of many different substances and yet are 1/7 the size of a human hair. They can cause respiratory ailments, and some very very tiny particles can enter the blood stream and cause lung disease and various heart issues.

Primary and Secondary pollutants

• primary pollutants are substances that are harmful in their directly emitted form.

• Secondary pollutants are harmful when they react with something such as sunlight.

The Clean Air Act of 1970

Two important policy strategies

• air quality standards

• regulation on the source of pollutants

• added a new policy in 1990 called tradable emission allowances to address sulfur dioxide emissions from coal-burning power plants. (example of cap-and-trade policy)

Energy policy and conservation act 1975 (CAFE)

• department of transportation set a minimum miles-per-gallon fuel economy standard for cars and vehicles considered light trucks. These are known as CAFE standards.

Biosphere 2

• self-sustaining ecological system closed to outside materials inputs and outputs.

• biospherians lived in biosphere 2 but required outside oxygen to survive. The designers failed to account for the complexities of oxygen exchange and nutrient cycling.

• biosphere 1 is the earth.

Closed and Open systems (earth)

• open system in terms if energy flow - the sun!

• closed in terms of matter (self-contained)

human chemical composition

• 3.8% other

• 3.2% hydrogen

• 9.5% hydrogen

• 18.5% carbon

• 65.0% oxygen

How lungs function

• tiny sacs called alveoli exchange oxygen and carbon dioxide as you inhale and exhale 

emergent properties

arise from the function of a system as a whole.

Models

• Scientists use models, or simplified representations of the real world, to show how certain aspects of a system function and interact.

• Stock and flow diagrams show how things like current in an electrical system moves from place to place and can run complex stimulations that show things like environmental systems.

Photosynthesis

• a series of chemical reactions that use water and CO2 and store this energy in molecules that are based on the element carbon, such as simple sugars.

Feedback

• a loop in a system responds to and produces changes in levels of stocks by affecting inflows and outflows of those stocks.

• example of positive feedback: melting icebergs

• Reinforcing feedback: a loop that responds to the direction of change in stock by enhancing that same direction of change. Biosphere 2 example: As the scientists were less nourished, they were less able to farm/do the things they needed to be nourished.

• balancing feedback: (negative feedback loop) it works against the direction in which stock is changing. *Adjustments made to “break the cycle”.

Phosphorus and the phosphorus cycle

• one of the building blocks of all living cells on Earth

• phosphates are the ionized forms of phosphorus and are key components of DNA and RNA that hold the genetic instructions for our cells to develop and reproduce, ATP and ADP that transport energy, and phospholipids that form cell membranes.

• Does not enter the atmosphere but cycles through the lithosphere and hydrosphere very slowly.

• used as a fertilizer, in detergents, and in steel production.

Stock and flow

Stock: a supply of something that we want to observe and measure over time.

Flow: the mechanisms and rates by which a stock changes over time.

Macronutrients

key elements that organisms use in large amounts (ex. nitrogen, carbon, oxygen)

Biogeochemical  cycle

a path that shows how matter on Earth flows through different parts of the environment.

Nitrogen fixation

• a process by which plants are able to take and use nitrogen (through their roots as opposed to from the air). free nitrogen is converted to soluble ammonium (NH4+) and nitrate (NO3-)

• this happens either through lightning strikes or through a bacteria known as diazotrophs which possess an enzyme that uses free nitrogen and hydrogen to produce ammonia. Bacteria also break down nitrogen compounds in animal waste and dead plant/animal matter + release ammonia (Ammonification) most of that ammonia then goes through nitrification as ammonia-oxidizing microorganisms convert ammonia into nitrogen compounds

Denitrification

Certain kinds of microorganisms underground or underwater use nitrogen compounds for respiration and convert them back into N2 gas, returning it to the atmosphere.

Ocean Acidification

• CO2, when dissolved in water, create carbonic acid.

• marine organisms have more difficulty building their shells and skeletons:(

Methanogens

• release methane as a by-product into the atmosphere

• carbon can move from the biosphere to the atmosphere through decomposing microorganisms known as methanogens

• thrive in oxygen-free environments, such as wetlands, hot springs, hydrothermal vents in the ocean and in animal digestive tracts

• cattle release methane from their guts through belching, flatulence, and defecation.

the iceberg model

• events: what occurred?

• pattern/trends: What long-term patterns have been observed?

• underlying structures: What causes these long-term trends?

• mental models: What do people think and feel about the system?

The Instrumental period

The current era in which we have access to temperature readings taken directly with instruments such as thermometers.

geothermal gradient

• the crust gets progressively hotter at deeper depths, resulting in the geothermal gradient, which describes how temperature increases with depth in Earth’s crust due to decaying radioactive elements.

Proxy

an observable and measurable phenomenon that serves as an indirect indicator of changes in climate.

paleoclimates

ancient climate conditions understood through use of proxies.

The greenhouse effect

Any system where a barrier causes an inflow of energy that outpaces the outflow such that the interior warms.

IPCC

The international panel on climate change