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Environmental Chemistry

Glossary of Important Terms

Chapters 1 & 2

Ecology

The study of environmental factors that affect organisms and how organisms interact with these factors and with each other.

Atmosphere

The thin layer of gases that cover Earth’s surface. Reservoir of gases, moderates Earth’s temperature, absorbs energy and damaging ultraviolet radiation from the sun, transports energy away from equatorial regions and serves as a pathway for vapor-phase movement of water in the hydrolic cycle.

Biosphere

Composed of all living entities on Earth.

Geosphere

Consists of the solid earth, including soil, which supports most plant life.

Lithosphere

The part of the geosphere that is directly involved with environmental processes through contact with the atmosphere, the hydrosphere, and living things. Varies from 50 to 100 km in thickness. Consists of outer mantle and crust.

Hydrosphere

Contains the Earth’s water.

Environmental Chemistry

The study of the sources, reactions, transport, effects, and fates of chemical species in water, soil, and air environments and the effects of technology thereon.

Ecosystem

Consists of an assembly of mutually interacting organisms and their environment in which materials are interchanged in a largely cyclical manner.

Pollutant

A substance present in greater than natural concentration as a result of human n activity that has a net detrimental effect upon its environment or upon something of value in that environment.

Contaminant

Cause deviations from the normal composition of an environment. Are not classified as pollutants unless they have some detrimental effect.

Hazardous waste

A potentially dangerous substance that has been discarded, abandoned, neglected, released or designated as a waste material, or one that may interact with other substances to pose a threat.

Aquatic Chemistry

The branch of environmental chemistry that deals with chemical phenomena in water.

Hydrology

The study of water

Limnology

The branch of science dealing with characteristics of freshwater, including biological properties as well as chemical and physical properties.

Oceanography

The science of the ocean and its physical and chemical characteristics.

Eutrophication

Relatively high productivity is required for the support of fish. Excessive productivity can result in choking by weeds and can cause odor problems. The growth of algae may become quite high in very productive water, with the result that the concurrent decomposition of dead algae reduces oxygen levels in the water to very low values.

Dissolved Oxygen (DO)

Frequently the key substance in determining the extent and kinds of life in a body of water.

Biochemical Oxygen Demand (BOD)

Another important water-quality parameter. It refers to the amount of oxygen utilized when the organic matter in a given volume of water is degraded biologically. (Chapter 7)

Dispersion Aerosols

Colloidal-sized particles in the atmosphere formed by grinding up bulk matter .

Condensation Aerosols

Particles formed from chemical reactions of gases.

 

Chapter 3

Strong Acid

(release H+ ions) Give up protons easily. ex HCl and H2SO4

Strong Base

Accept and hold proton tightly. ex Hydroxide ion

Weak Acid

Don’t give up protons easily. ex CH3COOH

Weak Base

Have little affinity for a proton. ex Chloride ion

pH

A number between 0 and 14 that describes the acidity of an aqueous solution. Mathematically, pH is equal to the negative logarithm of a solution’s H3O+ concentration.

Alkalinity

The capacity of water to accept H+ ions (protons).

Acidity

The capacity of the water to neutralize OH?.

 

Chapter 4

Nernst Equation

Used to account for the effect of different activities upon electrode potential.

 

Chapter 5

Colloidial particles

Particles which have some characteristics of both species in solution and larger particles in suspension, which range in diameter form about 0.001 micrometer (m m) to about 1m m, and which scatter white light as a light blue hue observed at right angles to the incident light.

Tyndall effect

The characteristic light scattering phenomenon of colloids results from their being the same order of size as the wavelength of light.

Hydrophilic colloids

Generally consist of macromolecules, such as proteins and synthetic polymers, that are characterized by strong interaction with water resulting in spontaneous formation of colloids when they are placed in water.

Hydrophobic colloids

Interact to a lesser extent with water and are stable because of their positive or negative electrical charges.

Association colloids

Consist of special aggregates of ions and molecules called micells.

Micells

A spherical cluster formed by the aggregation of soap molecules in water.

 

Chapter 6

Bacteria

Single-celled prokaryotic microorganisms that may be shaped as rods (bacillus), spheres (coccus), or spirals (vibrios, spirilla, spirochetes).

Fungi

Nonphotosynthetic organisms, larger than bacteria, aerobic and can thrive in more acidic media than bacteria. Important function is the break down of cellulose in wood and other plant materials.

Protozoa

Microscopic animals consisting of single eukaryotic cells.

Algae

Microscopic organisms that subsist on inorganic nutrients and produce organic matter from carbon dioxide by photosynthesis.

Virus

Microorganism...

Prokaryotes

Microorganisms that lack a nuclear membrane so that their nuclear genetic material is more diffuse in the cell.

Eurkaryotes

Have well defined cell nuclei enclosed by a nuclear membrane.

Producers

Utilize light energy and store it as chemical energy.

Reducers

Break down chemical compounds to more simple species and thereby extract the energy needed for their growth and metabolism

Chemotrophs

Use chemical energy derived from oxidation-reduction reactions for their energy needs.

Phototrophs

Utilized light energy from photosynthesis.

Autotrophs

Use carbon dioxide and ionic carbonates for the C that they require.

Heterotrophs

Obtain their carbon from other organisms.

 

Chapter 7

Classes of Water Pollutants

Class of Pollutant Significance
Trace elements
                Heavy metals
                Organically-bound metals
Health, aquatic biota
Health, aquatic biota
Metal transport
Radionuclides Toxicity
Inorganic pollutants
                 Asbestos
                 Algal nutrients
                 Acidity, alkalinity, salinity
                               (in excess)
Toxicity, aquatic biota
Human health
Eutrophication

Water quality, aquatic life
Trace organic pollutants
                Polychlorinated biphenyls
                Pesticides
                Petroleum wastes
Toxicity
Possible biological effects
Toxicity, aquatic biota, wildlife
Effect on wildlife, esthetics
Sewage, human, animals’ wastes
                Biochemical oxygen demand
                Pathogens
                Detergents
Water quality, oxygen levels
Water quality, oxygen levels
Health effects
Eutrophication, wildlife, esthetics
Chemical carcinogens Incidence of cancer
Sediments Water quality, aquatic biota, wildlife
Taste, odor, and color Esthetics

 

Chapter 8

Methods to treat waste water

Municipal water treatment

Treatment of water for industrial use

Sewage Treatment

Primary treatment

Consists of the removal of insoluble matter such as grit, grease, and scum from water. Process involves screening and solids are scraped off and disposed of.

Grit Removal

Practiced to prevent grit accumulation in other parts of the treatment system, to reduce clogging of pipes and other parts, and to protect moving parts from abrasion and wear. Process involves allowing the grit to settle in a tank under conditions of low velocity and then it is scraped mechanically from the bottom of the tank.

Primary sedimentation

Removes both settleable and floatable solids. Tendency for particles to aggregate, sometimes aided by the addition of chemicals.

Secondary treatment

Designed to remove BOD, usually by taking advantage of the same kind of biological processes that would other wise consume oxygen in water receiving the wastewater. Microorganisms provided with added oxygen are allowed to degrade organic material in solution or in suspension until the BOD of the waste has been reduced to acceptable levels.

Trickling filter

One of the simplest biological waste treatment processes. Wastewater is sprayed over rocks or other solid support material covered with microorganisms. The structure of the trickling filter is such that contact of the wastewater with air is allowed and degradation of organic matter occurs by the action of the microorganisms.

Activated Sludge Process

Probably the most versatile and effective of all waste treatment processes.

 

Chapter 9

Atmosphere

Two major components

Nitrogen 78.08%

Oxygen 20.955

Two minor components

Argon 0.934%

Carbon dioxide 0.035%

Four more noble gases

Neon 1.818 x 10-3%

Krypton 1.14 x 10-4%

Helium 5.24 x 10-4%

Xenon 8.7 x 10-6%

Atmospheric air may contain 0.1 to 5% water by volume, with a normal range of 1 to 3%.

Protective, from atmosphere

Source of Carbon Dioxide for plant photosynthesis and oxygen for respiration

It absorbs most of the cosmic rays from outer space

It absorbs most electromagnetic radiation from the sun, filtering out damaging ultraviolet radiation

Reabsorbs infrared radiation

Stabilizes Earth’s temperature

Scale height equation

Ph = POe-Mgh/RT

Solar flux

Energy received at the surface of the outer atmosphere,

(also called insolation) = 1.34 x 103 w/m2

Inversions

Conditions characterized by high atmospheric stability. They limit the vertical circulation of air, resulting in air stagnation and the trapping of air pollutants in localized areas.

Microclimates

Highly localized climatic conditions. The climate that organisms and objects on the surface are exposed to close to ground, under rocks, and surrounded by vegetation and it often quite different form the surrounding macroclimate.

Atmosphere

The thin layer of mixed gases covering the earth's surface.

Stratosphere

The portion of the earth's atmosphere between approximately 15 km and 50 km in altitude where ozone is formed by the reaction of ultraviolet light on dioxygen molecules.

Troposphere

The portion of the earth's atmosphere that is closest to the earth's surface (from 0 to 15 km in altitude).

Mesosphere

The portion of the earth's atmosphere between approximately 50 and 85 km, where molecules exist as charged ions caused by interaction of gas molecules with intense UV light.

Chapter 10

Atmospheric particles (Table 10.1)

Aerosol

Colloidal-sized atmospheric particle.

Condensation aerosol

Formed by condensation of vapors or reactions of gases.

Dispersion aerosol

Formed by grinding of solids, atomization of liquids, or dispersion of dusts.

Fog

Term denoting high level of water droplets.

Haze

Denotes decreased visibility due to the presence of particles

Mists

Liquid particles

Smoke

Particles formed by incomplete combustion of fuel

Stoke’s Law

 

Chapter 11

Sulfur Cycle (Figure 11.1)

 

 

 

 

 

 

 

 

Fate of CO in the Atmosphere

Equations 11_3_1-11_3_5.gif (5022 bytes)

Rxs of sulfur dioxide conversion

Equations 11_5_1-11_5_6.gif (4914 bytes)

Major Stack Gas Scrubbing Systems*

Process Chemical Reactions Major Advantages or Disadvantages
Lime slurry
scrubbing**
Eq11_1.gif (2243 bytes) Up to 200 kg of lime are needed per metric ton of coal, producing huge quantities of waste product.
Limestone slurry
scrubbing**
EQ11_2.gif (2424 bytes) Lower pH than lime slurry, not so efficient.
Magnesium
oxide scrubbing
EQ11_3.gif (2822 bytes) The sorbent can be regenerated, off site, if desired.
Sodium-
base
scrubbing
EQ11_4.gif (4819 bytes) No major technological limitations. Relatively high annual costs.
Double alkali** EQ11_5.gif (5173 bytes) Allows for regeneration of expensive sodium alkali solution with inexpensive lime.

*For details regarding these and more advanced processes, see (1) Satriana, M., New
Developments in Flue Gas Desulfurization Technology, Noyes Data Corp., Park Ridge, NJ, 1982, and (2) Takeshita, M. and H. Soud, FGD Performance and Experience on Coal-Fired Plants, Gemini House, London, 1993.
**These processes have also been adapted to produce a gypsum product by oxidation of CaSO3 in the spent scrubber medium:

CaSO3 + O2 + 2 H2O ? CaSO4 2 H2O(s)

Gypsum has some commercial value, such as in the manufacture of plasterboard, and makes a relatively settleable waste product.

Removal Technologies (Table 11.1)

                   fig 11.3.gif (15228 bytes)

 

Three Oxides of Nitrogen

 

Chapter 12

Know structures

CFC-11
CFC-12
TCE
hexachlorobenxene
Halon-1211
Halon-1301
polychlorinated dibenzo-p-dioxins
polychlorinated dibenzofurans

 

Chapter 13

Generalized Reaction Scheme for Photochemical Smog Formation

 

Chapter 14

Global warming

Acid Rain

Precipitation made acidic by the presence of acids stronger than CO2(aq).
Ozone Layer destruction

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Environmental Chemistry -- ENV 440
Last Updated:  09/02/99