Environmental science chp 1-5

ENV 1301

what is environmental studies?

emphasize the social sciences; involves the scientific study of the environment and our interactions with it

interdisciplinary: brings techniques and research from multiple disciplines together

natural resources

substances and energy sources that we take from the environment and rely upon to survive

renewable vs nonrenewable (natural resources)

renewable: replenished over short periods (sunlight, water, trees)

nonrenewable: formed much slowly and are no longer available once depleted (oil)

ecosystem services

provisioning: water, food, timber, fuel

regulating: climate regulation, water regulation, erosion

cultural: recreation, aesthetic, spiritual, educational

supporting: soil formation, nutrient cycle

Earth’s natural capital

store of resources and ecosystem services (like a bank account)

how has the agricultural revolution and industrial revolution effected human population?

agricultural revolution: people began to grow crops and domesticate animals

industrial revolution: shifted life toward an urban society powered by fossil fuels

ecological footprint

cumulative area of land and water needed to provide resources and waste disposal for a person

overshoot

surpassing earth’s capacity to sustainably support our population

humans are using renewable resources 73% faster than they are being replenished

estuary

partially enclosed body of water with a mixture of salt and freshwater (Chesapeake Bay)

descriptive science

involves researching organisms, materials, and systems that are new or not well known

hypothesis driven science

uses experiments to test hypotheses as part of the scientific method

independent vs dependent variable (scientific method)

independent: a condition that changes and is to be tested

dependent: resulting condition that depends on the independent variable

in a controlled experiment, only the independent variable is changed; control group does not change and is used as a comparison point

manipulative experiments (scientific method; testing hypotheses)

researcher actively chooses and manipulates the independent variable

natural experiments (scientific method; testing hypotheses)

compare how different variables are expressed in naturally occurring but different contexts

scientific method

observation → questions → hypothesis → predictions → test → results

if predictions fail to reject hypothesis then test a new prediction

if hypothesis and results dont match; reject hypothesis and form a new one

how does a hypothesis turn into a theory?

if a hypothesis survives repeated testing and consistently predicts experiment outcomes accurately it may be turned into a theory (cell theory, plate tectonics, evolution)

3 types of scientific literature

peer-reviewed: articles, paper, and books that have been checked by other scientists (double blind review: scientist sends it out anonymously; anonymous editors)

gray literature: written by experts in the field targeted for other scientists but haven’t gone through peer review

popular press: everything you read, news, NYT magazine, written by journalists for public audience

primary vs secondary source

primary: scientist’s own findings

secondary: popular press describes the findings

normative vs philosophical ethics

normative: prescribes specific behavior (what to and not do)

philosophical: evaluates normative judgments and their supporting reasons

ecocentrism (environmental ethics)

effects on ecological systems, contain both living and nonliving items and relationship between them

biocentric (environmental ethics)

inherit value to all living things

anthropocentrism (environmental ethics)

value to nature only to the extent that it benefits humans in some way

John Muir

preservation ethic: environment should be protected in a pristine unaltered state

helped the US parks service (very biocentrism)

Gifford Pinochet

conservation ethic: people should put natural resources to use but have a responsibility to use them wisely

helped establish US forest service (anthropocentrism)

Aldo Leopold

healthy ecological systems depend on all their interacting parts (ecocentrism)

was a wolf hunter but changed his belief

environmental justice

fair and equitable treatment of all people with respect to environmental policy and practice

poor people and ethnic minorities tend to be more exposed to more pollution than wealthier people

distributional equity (environmental justice)

who gets what? (ex: who gets exposed to pollution?)

procedural equity (environmental justice)

who gets to take part in the decision making process?

recognition (environmental justice)

how are different viewpoints recognized in decision making process?

Robert D. Bullard (environmental justice framework)

right of all environmental degradation, stress prevention of public, evidence would be used to infer discrimination as apposed to intent, target resources where risk is greatest

What is a system?

network of relationships among parts that influence each other through the exchange of energy, matter, or information

4 types of Earth’s environmental systems

lithosphere: rock and sediment in the planet’s upper mantle and crust

atmosphere: air surrounding the planet

hydrosphere: all water (salt, fresh, liquid, vapor, ice)

biosphere: all living organisms of the Earth and the nonliving components that they interact with

feedback loops

system’s output may serve as input back into the same system

can stabilize or destabilize systems

negative vs positive feedback loops

negative: system moving in one direction acts as an input that causes the system to move in the opposite direction (too hot, seek shade, body cools)

positive: occur when increased output in a system leads to increased input, which further stimulates output (sun melts snow, more ground showing, land heats up)

dynamic equilibrium

negative feedback systems with process that move in opposing direction at equal forces (contributes to homeostasis)

matter and chemistry

matter: any material that has mass and occupies space

chemistry: studies the interactions of matter

law of conservation of matter

matter can be transformed into another type of substance but cannot be created or destroyed

elements

substances with specific properties that cannot be broken down into substances with other properties

atomic mass

determined by the number of protons and neutrons

isotopes

number of neutrons may vary which creates different masses

radioactive and radioisotopes

some isotopes can decay and change their identity by emitting particles and high energy radiation

isotopes with this property are called radioisotopes

watershed

area of land that drains into a body of water through rivers

nitrogen and phosphorus

nutrients from fertilizers, animal manure, and fossil fuels can create deadzones

hypoxia

too low on oxygen to support aerobic life

must abundant elements on earth

oxygen, hydrogen, silicon, nitrogen, and carbon

ions

atoms may gain or lose electrons

charge of an ion indicates how its electrons have been affected

ph scale

the acidity or alkalinity of a solution 0-14 (soap is basic 10, lemon juice acidic 2, pure water neutral 7)

molecules

combination of two or more atoms chemically bonded together (O2)

compound

if molecule is made of two or more different elements (water and carbon dioxide)

ionic bonds

ions of different charges attract and bind to each other

covalent bonds

electrons are shared between atoms that lack an electrical charge

mixtures and solutions

atoms and molecules come together and don’t react with each other

evenly distributed mixtures

organic compounds

carbon atoms joined together with covalent bonds

hydrocarbons

important class of organic compounds; contain hydrogen and carbon

polymers

long chains of repeated molecules

polymers and lipids referred to as macromolecules because they are so large

proteins

polymers made of amino acids

nucleic acids

include DNA and RNA, carry hereditary information

carbohydrates

simple and complex sugars such as glucose (blood sugar), cellulose, chitin

lipids

diverse group of molecules that do not dissolve in water (fats and oils, waxes, steroids)

2 types of energy

capacity to change the position, composition, or temperature of matter

potential: energy of position (river water held behind a dam)

kinetic: energy in motion (river water rushing through a dam downstream)

energy is able to be converted back and forth between the two forms

chemical energy

potential energy stored in the bonds among atoms

first law of thermodynamics vs second law of thermodynamics

1: energy can change from one form to another but it cannot be created or destroyed

2: nature of energy tends to change from a more ordered form to a less ordered form

autotrophs

use sun’s radiation directly to produce their own food (the process is called photosynthesis)

light reactions (photosynthesis)

chlorophyll uses solar energy to initiate a series of reaction

photosynthesis chemical equation

6 CO2 + 6 H2O + sun’s energy → C6H12O6 +6 O2

cellular respiration chemical equation

C6H12O6 +6 O2 → 6 CO2 + 6H2O

occurs in all living things; both autotrophs and heterotrophs (organisms that gain energy by feeding on other organisms)

ecosystem

all organisms and nonliving entities that occur and interact in a particular area at the same time

primary production, gross primary production, net primary production, secondary production

primary: conversion of solar energy into chemical bonds in sugars

gross primary: total chemical energy produced by autotrophs

net primary: energy that remains after respiration is used to generate biomass

secondary: energy used by consumers to generate their own biomass

which ecosystems have the highest net primary production vs low?

high: wetlands, tropical forests

low: deserts, tundra, open ocean

landscape ecology

spatial patterns above the ecosystem level

source, sink, flux

reservoir releases more materials than it accepts = source

reservoir accepts more materials than it releases = sink

flux is the rate at which materials move between reservoirs

water cycle

evaporation: converts liquid to gas taking into atmosphere

transpiration: release of water vapor by plants through their leaves

precipitation: rain

groundwater: water soaks down through soil and rock → aquifers are regions of rock and soil that are underground reservoirs of water (upper limit of groundwater in an aquifer is called water table)

carbon cycle

producer pull CO2 out of air and use it → autotrophs, consumers, decomposers consume organic molecules and release some carbon dioxide

nitrogen cycle

nitrogen fixation: combine nitrogen with hydrogen to form ammonia that can be taken up by plants

nitrogen fixing bacteria: convert nitrogen gas into ammonia

nitrification: bacteria convert ammonium ions into nitrite ions which plants can directly take up

denitrifying bacteria: convert nitrates back into nitrogen gas, releasing it back into the atmosphere and complete the cycle

phosphorus cycle

weathering rocks release phosphate into water → sink to the bottom of water → aquatic organisms take up phosphate from surrounding water → terrestrial organisms take up phosphates

species

classification of organisms whose members can interbreed and produce fertile offspring

natural selection

process that favors certain inherited characteristics over others causing them to be passed on more frequently

organisms face a constant struggle to survive and reproduce, organisms tend to produce more offspring than can survive to maturity, individuals of a species vary in their attributes

adaptation

genes that lead to better reproductive success will eventually evolve through the entire population

convergent evolution

unrelated species living in similar environments may independently acquire similar traits

artificial selection

humans conduct selection under our own wants

biodiversity

variety of life across all levels

speciation

process by which new species are generated

allopatric speciation

populations become physically separated over a geographic distance

phylogenetic tree

scientist represent the history of divergence

know how to read one

extinction

occurs when environment changes more rapidly than the species can adapt; small and specialized populations are most vulnerable

earth has seen 5 mass extinction events (50-95% of species wiped) some think we are in the 6th (habitat destruction, invasive species, pollution, hunting, climate change)

species-area relationship

S=cA^z

S= number of species c= constant A= habitat area Z= slope of curve when plotted

E/MSY (current extinction rate)

E= extinction, MSY= million species per year

community ecology and ecosystem ecology

community: studies populations of species that live and interact within an area interactions

ecosystem: flow of energy and nutrients between the living and nonliving parts

specialist vs generalist niche

niche: organisms role in its community

specialist: narrow niche

generalist: utilize a variety of resources

population distribution

spatial arrangement of organisms within an area; random, uniformed, clumped

population change is determined by 4 factors

natality: birth

mortality: death

immigration: arrival

emigration: departure

population growth rate equation

(birth rate - death rate) + (immigration rate - emigration rate)

limiting factors and carrying capacity

population is constrained by physical, chemical, biological factors in environment

maximum population size of a species that an environment can sustain

density dependent vs density independent

dependent: rise and fall with population density (disease, predation)

independent: unaffected by population density (natural disasters)

competition, predation, mutualism

competition: both species don’t benefit

predation: one species benefits the other doesn’t

mutualism: both species benefit

resource partitioning

individuals share resources in different ways (birds in trees)

trophic level

species in a community are given a rank within the feeding hierarchy

producers (plants) → primary consumers → secondary consumers → tertiary consumer

detritivores scavenge waste and dead bodies; decomposers break down nonliving matter into smaller molecules

energy is lost through heat or maintenance; the higher the consumer the less biomass

keystone species

species that has an impact far greater than its abundance

trophic cascade

top predators are lost, primary consumers will overconsume producers and alter ecosystem

succession, pioneer species, climax community

severe disturbances may eliminate most species initiating a series of change

begins with the colonization of pioneer species (spread over long distances easily and are adapted for growing quickly)

pioneers are overtaken by longer living climax community species