ENSP 2341 FINAL Study Guide

Atom

smallest particles of any element that is still an element

Molecule

groups of 2 or more atoms

Compound

groups of 2 or more different elements

Biogeochemical cycle

track the flow of matter and energy through the different “spheres”

Reservoir, pools, fluxes

**Reservoir/pools -** “pools”, major compartments that contain the substance

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**Fluxes -** rates at which substances moves between reservoirs (mass per unit time)

Mycorrhizal fungus

* Mycorrhizae - Fungi that form symbiotic association with plant roots


* plays a big role in plant uptake of phosphorus

Humus

dark, organic material that forms in soil when plant and animal matter decays

Cation/ Anion

* **Cation:** Positively charged ions - hydrogen, magnesium, aluminum


* **Anion:** Negatively charged ions - sulfate, phosphate, nitrate, chloride, etc.

Cation exchange capacity

Quantity of cations that can be **adsorbed** by a soil expressed in milliequivalent of negative charge per 100 g dry soil (1 meq = the ability to adsorb and hold one milligram of H+)

Soil formation

* Soils begin to form when sediment, organic matter, or rock—(1) parent material—is first deposited or exposed, often by water, wind, or ice.


* Soils develop as parent material ages in place, changed by (2) climate, (3) soil organisms, and the (4) terrain over (5) time.

Lithosphere

outer layer \~ 100 km deep

Weathering (phys,chem, biol)

* **Physical Weathering:** Manual fragmentation of rocks through the action of wind, water, ice, temperature fluctuations, etc, without chemical change
* EXAMPLE:
* Water enters the joints in a rock
* Water freezes in the crack as temperatures fall at night and increase 9% in volume put pressure on the crack 
* Thawing occurs, followed by subsequent freezing the following night. Freeze-thaw cycles gradually widen the crack

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* **Chemical Weathering:** Chemical reactions between minerals and the environment (air, water)
* Main chemical weathering reactions are dissolution (also called carbonation), hydrolysis, and oxidation
* Weathering increases with more water, O2 and CO2 
* **Biological Weathering:** When roots penetrate the cracks, breaking up rocks, usually a mix of physical and chemical weathering

Soil pH

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* **Soil pH:** Measure of H+ ion activity in soil solution 
* The mineral content of the soil is what primarily determines the pH 
* Carbonate minerals tend to increase pH 
* When significant aluminum iron are present, the pH is lowered 

Soil salinity

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* **High concentration of salts in soils - Salinization:** 
* Caused by irrigation in arid systems - water evaporates and salt crystals left behind
* **Electrical Conductivity (EC) - Measures Salinity:**
* Salts increase a solution’s ability to conduct electrical current because the separation of charges provides a “pathway” for the current’s flow
* Units are in decisiemens per metre (dS/m)
* Low salinity = low dS/m ratings

Nitrogen fixation

Occurs when inert N (N2) is transformed to ammonium (NH4+)

Biological N fixation

Uses enzyme “nitrogenase”

* High-energy requirement, only occurs where bacterium has abundant carbohydrate supply

Haber-Bosch process

Converts hydrogen and nitrogen to ammonia

Denitrification

Process by which specialized bacteria break down NO3− and NO2− to N2 or N2O

Reactive nitrogen

**Nitrous oxide -** reactive nitrogen compound

Labile vs recalcitrant carbon

* **Labile:** most rapid turnover times


* **Recalcitrant:** resistant to decomposition

Soil organic matter

(SOM) is the portion of soil that is composed of living and dead things in various states of decomposition, such as plant roots and microbes.

Decomposition

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break-down of organic molecules

\n “CH2O” + O2 → H2O + CO2 + Nutrients

Photosynthesis

CO2 is removed from the atmosphere by primary producers

CO2 + 6 H2O + sunlight → C6H12O6 (glucose) + 6O2

Cellular respiration

all animals, plants, many fungi and some bacteria obtain \n energy through cellular respiration by breaking down sugars, fats, and amino acids with oxygen as part of their metabolism \n

C6H12O6 (glucose) + 6O2 → CO2 + 6 H2O + chemical energy (ATP) and heat

Methane cycle

* Wetlands are the major natural source of methane to the atmosphere


* Methanogens use CO2 or acetate in place of O2 as their terminal electron acceptor during metabolism, and produce methane in the process

Ocean acidification

The impacts of altered carbon cycle such as with land-use changes and fossil fuel emissions.

Increased CO2 + CH4 in the atmosphere has led to Ocean Acidification

Properties of water

Water has many unusual properties due to its **hydrogen bonding**

* Water is polar


* Water is an excellent solvent
* Water has high heat capacity
* Water has high heat of vaporization
* Water has cohesive and adhesive properties
* Water is less dense as a solid than as a liquid.

Hydrogen bonding

* Special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom (Hydrogen is positive and oxygen is negative) 


* Occur when H is covalently bonded to a small, highly electronegative atoms - **N, F, O**. This H can form an H- bond with another electronegative atom
* H bonds hold together double helical chains of DNA!

Polarity

separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end

Polar covalent bonding

Slight difference in electronegativity (unequal sharing of electrons)

Ionic bonding

Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities

Point source pollution

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* Single large source 
* Can be traced back to the spot it came from

Non-point source pollution

* Diffuse source or many smaller point sources
* Can not be traced back to a point 
* **Nonpoint source water pollution from agriculture:** The largest source of water pollution in the U.S. (64% of pollutants into streams & 57% of pollutants entering lakes)

Dissolved oxygen

An indicator of water quality 

* High dissolved oxygen = Good water quality 


* **Sources of D.O in a body of water = photosynthesis, diffusion from atmosphere, wind cycling** 
* Salinity affects DO, the higher the salinity, the lower the DO concentration
* **Temperature and elevation affect DO**
* **Cold lakes can hold more dissolved oxygen than warm lakes** 
* **Low elevation lakes and rivers hold more oxygen than those at high elevation**

Oxygen-consuming wastes

* **Sources:** Human and animal feces; Industrial wastes from \n paper mills, tanneries, food processing plants, slaughterhouses, meatpacking plants
* **Fate:** Bacteria and fungi break down organic detritus through \n aerobic decomposition. When overloaded with org matter, \n aerobic decomposers proliferate and DO consumed more \n rapidly than can be replaced from atmosphere

Biological oxygen demand

**BOD =** capacity of organic material in a sample of water to consume the DO

Amount of dissolved oxygen needed by **aerobic decomposers** to break down **organic materials** in a certain volume over a 5–day incubation period at 20°C \n \n The higher the **BOD**, the greater the amount of reactive organic compounds in the water

Cultural eutrophication

Cultural eutrophication occurs when human water pollution speeds up the aging process by introducing sewage, detergents, fertilizers, and other nutrient sources into the ecosystem.

Sedimentation

* Sediments – undissolved particles in water
* Natural erosion of rock and soil leads to sedimentation
* Increased rates of sedimentation due to...
* Development, clear-cutting, strip mining, overgrazing, plowing, etc.

Turbidity

cloudiness caused by suspended particles

Redox potential, (Eh)

Redox potential (voltage) is a measure of how easily a metal (or other ion) will give up electrons or retain electrons, not the likelihood for a specific oxidation or reduction reaction occurring.

Anoxic/ Anaerobic

A condition in which the aquatic (water) environment does not contain dissolved oxygen (DO), which is called an oxygen deficient condition.

* the absence of free oxygen

Dose-response

A relationship exists between the dose of an agent and the biological response.

Carcinogen

cause cancer – cells reproduce and grow abnormally producing a malignant tumor

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(PAHs, aromatic amines, vinyl chloride, asbestos, metal compounds)

Teratogen

cause birth defects

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(alcohol, cigarette smoke)

Mutagen

chemicals that alter genes and chromosomes to cause heritable abnormalities in offspring

Endocrine disrupter

Synthetic chemicals that block, mimic, or otherwise interfere with naturally produced hormones

Cancer cluster

a greater than expected number of the same or etiologically related cancer cases that occurs within a group of people in a geographic area over a defined period of time.

Epidemiology

Epidemiology is the study of how often diseases occur in different groups of people and why.

Persistence

EPA calculates persistence as half life of chemical in different media (atmosphere, water, soil, sediments)

Bioavailability (of heavy metals)

Bioavailability of heavy metals in soils is very important for their fate in their environment and uptake in plants

* different metals have different bioavailability
* bioavailability is dependent on metal speciation and on different physio-chem properties of soils

Halogenated hydrocarbon

halogenated meaning a chemical compound containing F, Cl, Br, or I

Aromatic hydrocarbon

Aromatic = cyclic, flat molecule with ring of resonance bonds. Very stable!

* Simplest is benzene
* Can be monocyclic or \n polycyclic (PAH)
* Can be halogenated
* Chemical compound containing F, Cl, Br, or I

Grasshopper effect

**Grasshopper effect, global distillation =** geochemical process by which POPs are transported from warmer to colder regions of the earth (poles, mountaintops) \n

Semi-volatile: compounds are vaporized at high temperature

* Travel to low temperature, condenses repeatedly..

Acid mine drainage

Acid mine drainage is the formation and movement of highly acidic water rich in heavy metals.

* forms through the chemical reaction of surface water (rainwater, snowmelt, pond water) and shallow subsurface water with rocks that contain sulfur-bearing minerals,
* results in sulfuric acid

Impacts of heavy metals

* Most heavy metals cause environmental and atmospheric pollution, and may be lethal to humans.
* Heavy metals can become strongly toxic by mixing with different environmental elements, such as water, soil, and air, and humans and other living organisms can be exposed to them through the food chain.

Stratosphere

Absorption of UV radiation by ozone increases temperature

Troposphere

temperature decreases with increasing altitude

* Warmed air that rises from the surface of Earth
* Pressure decreases with altitude, as air rises, it enters zone of lower pressure and expands and cools

Residence time

mean residence time is calculated as the total mass divided by the flux into or out of the atmosphere over a given time

* gases that have short residence times are distributed unevenly

Atmospheric composition

Dry air made up of two major components:

* Nitrogen (N2)78.08%
* Oxygen (O2) 20.95%

Two minor components:

* Argon (Ar) 0.934%
* Carbon Dioxide(CO2) 0.035%

Water vapor:

* Water makes up 0.1 - 5% of the atmosphere by volume, (usually \~1-3%)

Mean free path

* Average distance travelled before colliding with another molecule


* Greater at higher altitudes since pressure is so low

Aerosols /Particulate matter

Aerosols = minute particles, diameter < 10 μm

Particulates = larger particles

Air pollutant

Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials

Primary vs Secondary Pollutants

* Primary pollutant - air pollutant emitted directly from a source
* Secondary pollutant - not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere

Mobile sources

These are Anthropogenic Sources

\- Motor vehicles

Stationary sources

These are Anthropogenic Sources

\- Power plants

\- Industrial facilities

Acid deposition

Acid rain: rainfall whose pH is less than 5.6; caused by nitrogen oxides (NOx), sulfur dioxide (SO2), and ammonia (NH3) which form nitric and sulfuric acid and NH4+ when mixed with water.

4NO2 + 2H2 + O2 → 4HNO3 (nitric acid) → acid rain

Photochemical smog

mix of atmospheric chemicals with anthropogenic emissions derived daily from fossil fuel burning

* Ozone, aldehydes, Peroxyacetyl nitrate (PAN)

Thermal inversion

…can increase air pollution

* Thermal inversions = cool air at the surface beneath warmer air above
* Restricts movement and dispersal of air pollutants

Greenhouse effect

The greenhouse effect is a process that occurs when gases in Earth's atmosphere trap the Sun's heat. This process makes Earth much warmer than it would be without an atmosphere. The greenhouse effect is one of the things that makes Earth a comfortable place to live.

Global warming potential

Is a relative measure of how much heat a greenhouse gas traps in the atmosphere compared to CO2.

Albedo

Amount of incident radiation reflected by a surface; does not contribute to the heating of the surface

Radiative forcing

Occurs whenever there is an imbalance in sunlight entering atmosphere and energy radiating back to space.

Infrared radiation

IR radiation is not energetic enough to break covalent bonds, but \n can change the vibrational/rotational motion of the molecule

Dipole moment

To absorb IR, molecule must undergo change in dipole moment

* When atoms in a molecule share electrons unequally, they create a __**dipole moment.**__
* This can occur between two ions in an ionic bond or between atoms in a covalent bond. Dipole moments arise from differences in electronegativity.
* CO2 has no net dipole moment, but it does undergo a change in dipole moment. H2O does both.

Carbon cycle

Soil organic matter/carbon cycle - based on continuously supplying carbon in the form of organic matter as a food source for microorganisms

Carbon sequestration

Capturing CO2 from the atmosphere for long-term storage

Fractional distillation

the separation of a mixture into its component parts, or fractions.

* Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize

Bond energy

energy required to break 1 mole of a particular kind of bond; same energy released if bond reformed

Hydraulic fracturing

technique used commonly in low-permeability rocks like tight sandstone, shale, and some coal beds to increase oil and/or gas flow to a well from petroleum-bearing rock formations.

Tar sands

= Sandstone + bitumen

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Extraction for oil

* Extraction – Hot water process separates bitumen from sand, water, and minerals – 2 tons tar sands to produce one barrel of oil

**Porosity, permeability**

Porosity and permeability of soil allow the migration and accumulation of petroleum under adequate trap conditions. 

Lithium mining

Lithium used for:

* batteries of electric vehicles, batteries of laptops and cell phones, glass and ceramics industry. 

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Environmental/social side effects include:

* use of large quantities of water and related pollution
* potential increase in carbon dioxide emissions
* production of large quantities of mineral waste
* increased respiratory problem
* alteration of the hydrological cycle

Radioactivity

The release of energy from the decay of the nuclei of certain kinds of atoms and isotopes

Ionizing radiation

Not energetic enough to break covalent bonds, but can change the vibrational/rotational motion of the molecule 

Alpha, beta, gamma radiation

* Gamma rays are the most harmful external hazard. 
* Beta particles can partially penetrate skin, causing “beta burns”. 
* Alpha particles cannot penetrate intact skin. Gamma and x-rays can pass through a person damaging cells in their path.

Radioactive decay

More unstable = more raid decay, shorter half life 

* ΔN/Δt = kt
* N= number of nuclei
* No = initial N
* k= rate constant
* t= time

Decay rate – ½ life

A half-life is the time it takes for a certain amount of a pesticide to be reduced by half. 

Half life t1/2 = 0.693/k

Nuclear fission

* 1939 - Manhattan Project began to develop atomic bomb


* Einstein sent letter to FDR warning that the Germans were already working on a bomb based on nuclear fission


* Differs from other types of nuclear reactions in that it can be amplified via a nuclear chain reaction 
* Neutrons released by each fission event can trigger more events, in turn releasing more neutrons and causing more fissions 
* This continues with the release of ever increasing amounts of energy until all the uranium nuclei have been split

Isotope

Atoms with the same number of protons, but different number of neutrons and therefore different atomic mass

Fissile isotope

* Most common fissile isotopes are U-235 and Pu-239


* Process by which atoms are split and energy is released

Nuclear chain reaction

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* Neutrons released by each fission event can trigger \n more events, in turn releasing more neutrons and causing more fissions
* This continues with the release of ever increasing amounts of energy until all the uranium nuclei have been split

Critical mass

The smallest mass of a fissionable material (U-235) that will sustain a nuclear chain reaction at a constant level.

Radwaste

* Radioactive waste, remains radioactive for up to hundreds of thousands of years
* Four options for dealing with radwaste:
* Cooling ponds – temporary onsite storage
* Dry-cask storage – stored onsite in barrels
* Fuel reprocessing – a nuclear proliferation threat because reprocessed fuel can be used in weapons
* Deep-geological storage – long-term underground storage

Life Cycle Analysis

* Developed in the 1960s, motivated by concerns over limitations of raw materials & energy resources.


* Considers everything that goes into the making, using, transporting, and disposing of a product

Cradle-to-Gate

Cradle-to-gate refers to the carbon impact of a product from the moment it's produced to the moment it enters the store.

* some companies prefer to measure cradle-to-gate because they've designed a product that can be easily recycled or composted, avoiding the landfill altogether.

**Cradle-to-Grave**

Products made with no contribution to the environment and made to end up as waste.

Cradle-to-Cradle

Industry must protect and enrich ecosystems and nature's biological metabolism while also maintaining a safe, productive technical metabolism for the high-quality use and circulation of organic and technical nutrients.

Technical nutrient

Technical nutrients would be manufactured/created

Biological nutrient

Biodegradable

Upcycling

Making a product better